Merge branch 'main' into renovate/minor-patch/org.jacoco-jacoco-maven-plugin-0.x

Reviewed-on: #29

.gitea/workflows/build.yaml

@@ -5,7 +5,7 @@ on:
 
 jobs:
   verify:
-    runs-on: agiledancers-mini-pc
+    runs-on: mini-pc
     env:
       CI: 'true'
       TARGET_PLATFORM: ${{ vars.TARGET_PLATFORM }}
@@ -19,21 +19,23 @@ jobs:
         uses: https://github.com/actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
         with:
           persist-credentials: false
+      - name: Verify pinned engineering resources
+        run: python3 scripts/engineering.py --check
       - name: Identify workflow attempt
         # Gitea 1.25 does not populate gitea.run_attempt. Use a unique value for
         # container names and diagnostic artifacts, including reruns of one SHA.
-        run: java ci/Ci.java attempt
+        run: java generated/ci/Ci.java attempt
       - name: Build and test both images
-        run: java ci/Ci.java verify
+        run: java generated/ci/Ci.java verify
       - name: Publish verified main images
         if: success() && gitea.ref == 'refs/heads/main'
         env:
           REGISTRY_USER: ${{ secrets.REGISTRY_USER }}
           REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN }}
-        run: java ci/Ci.java publish
+        run: java generated/ci/Ci.java publish
       - name: Collect diagnostics and clean up test containers
         if: always()
-        run: java ci/Ci.java cleanup
+        run: java generated/ci/Ci.java cleanup
       - name: Retain diagnostics for fourteen days
         if: always()
         uses: https://github.com/actions/upload-artifact@ff15f0306b3f739f7b6fd43fb5d26cd321bd4de5

.gitea/workflows/deploy.yaml

@@ -3,7 +3,7 @@ on:
   workflow_dispatch:
     inputs:
       mode:
-        description: 'Release mode — deployment can erase data until S16 is implemented'
+        description: 'Release mode — export legacy data before the first S16 deployment'
         required: true
         type: choice
         default: new
@@ -28,7 +28,7 @@ on:
 jobs:
   deploy:
     if: gitea.ref == 'refs/heads/main'
-    runs-on: agiledancers-mini-pc
+    runs-on: mini-pc
     env:
       CI: 'true'
       GITEA_SERVER_URL: ${{ gitea.server_url }}
@@ -42,9 +42,11 @@ jobs:
         uses: https://github.com/actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
         with:
           persist-credentials: false
+      - name: Verify pinned engineering resources
+        run: python3 scripts/engineering.py --check
       - name: Identify workflow attempt
-        run: java ci/Ci.java attempt
-      - name: Release verified images — data can be lost until S16
+        run: java generated/ci/Ci.java attempt
+      - name: Release verified images — persistent PostgreSQL storage
         env:
           RELEASE_MODE: ${{ inputs.mode }}
           RELEASE_INCREMENT: ${{ inputs.increment }}
@@ -57,7 +59,7 @@ jobs:
           DEPLOY_REGISTRY: ${{ vars.DEPLOY_REGISTRY }}
           DEPLOY_SSH_KEY: ${{ secrets.DEPLOY_SSH_KEY }}
           DEPLOY_KNOWN_HOSTS: ${{ secrets.DEPLOY_KNOWN_HOSTS }}
-        run: java ci/Ci.java deploy
+        run: java generated/ci/Ci.java deploy
       - name: Retain deployment diagnostics for fourteen days
         if: always()
         uses: https://github.com/actions/upload-artifact@ff15f0306b3f739f7b6fd43fb5d26cd321bd4de5

.gitea/workflows/rollback.yaml

@@ -5,7 +5,7 @@ on:
 jobs:
   rollback:
     if: gitea.ref == 'refs/heads/main'
-    runs-on: agiledancers-mini-pc
+    runs-on: mini-pc
     env:
       CI: 'true'
       GITEA_SERVER_URL: ${{ gitea.server_url }}
@@ -19,9 +19,11 @@ jobs:
         uses: https://github.com/actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
         with:
           persist-credentials: false
+      - name: Verify pinned engineering resources
+        run: python3 scripts/engineering.py --check
       - name: Identify workflow attempt
-        run: java ci/Ci.java attempt
-      - name: Restore previous successful release — data can be lost until S16
+        run: java generated/ci/Ci.java attempt
+      - name: Restore previous successful release — requires a compatible database schema
         env:
           RELEASE_TOKEN: ${{ secrets.RELEASE_TOKEN }}
           DEPLOY_HOST: ${{ vars.DEPLOY_HOST }}
@@ -31,7 +33,7 @@ jobs:
           DEPLOY_REGISTRY: ${{ vars.DEPLOY_REGISTRY }}
           DEPLOY_SSH_KEY: ${{ secrets.DEPLOY_SSH_KEY }}
           DEPLOY_KNOWN_HOSTS: ${{ secrets.DEPLOY_KNOWN_HOSTS }}
-        run: java ci/Ci.java rollback
+        run: java generated/ci/Ci.java rollback
       - name: Retain deployment diagnostics for fourteen days
         if: always()
         uses: https://github.com/actions/upload-artifact@ff15f0306b3f739f7b6fd43fb5d26cd321bd4de5

AGENTS.md

@@ -1,22 +1,26 @@
-# Project skills and specifications
+# Shared skills and specifications
 
-- Project skills are stored in `skills/`; specifications belong in `specs/`.
-- For code reviews, read and follow `skills/code-review/SKILL.md`. If no
-  dedicated Skill tool is available, load the file directly.
-- Use `grill-me` only when the user explicitly requests it, for example
-  `Use grill-me to review this plan` or `Gebruik grill-me voor dit ontwerp`.
-- Before using it, read `skills/grill-me/SKILL.md` and its dependency
-  `skills/grilling/SKILL.md`. If no dedicated Skill tool is available, load these
-  files directly and follow their instructions within the available tools.
-- Installing or mentioning a skill does not start an interview. Do not apply
-  `grilling` automatically to ordinary development requests.
-- Keep the upstream skill files unchanged. Source revision and license are
-  recorded in `skills/upstream.json` and `skills/LICENSE.mattpocock`.
+- Shared agent workflows live in [landscape skills](http://192.168.2.28:3000/wanjakrah/landscape/src/branch/main/skills/README.md).
+  Read the requested SKILL.md there before applying it. A sibling checkout is optional.
+- For code reviews use landscape's skills/code-review/SKILL.md with docs/backend-review.md.
+- Use grill-me only when explicitly requested, with its skills/grilling/SKILL.md dependency.
+  Installing or mentioning a skill starts no interview.
+- Keep upstream skills unchanged; licenses and revision records live in landscape/skills/.
+- Specifications and ADRs belong to landscape. Engineering owns pinned build resources.
 
 # Backend changes and reviews
 
 - Before changing backend Java, read `CODING_STANDARDS.md`.
-- For reviews, use `skills/code-review/SKILL.md` together with
+- For reviews, use landscape's `skills/code-review/SKILL.md` together with
   `docs/backend-review.md`. Keep upstream skills unchanged.
 - Obtain maintainer agreement before adding any standards waiver; record its
   narrow scope and reason alongside the affected code or configuration.
+
+# Landscape and engineering
+
+- Read current [landscape guidance](http://192.168.2.28:3000/wanjakrah/landscape),
+  including applicable ADRs and specifications. This repository owns its implementation.
+- Engineering resources are pinned by `engineering.lock.json`. Do not edit
+  `generated/`; change engineering and deliberately adopt a released version.
+- Regenerate with `mvn -N -Pregenerate-engineering validate`; check with
+  `python3 scripts/engineering.py --check`. No sibling checkout is needed.

CODING_STANDARDS.md

@@ -1,255 +1,11 @@
-# Backend coding standards
+# Agile Dancers coding standards
 
-This document is the authoritative policy for handwritten production and test Java
-in `agiledancers-be`. Generated code and Java helpers outside that module are out
-of scope. Existing frontend conventions in README.md and agiledancers-fe remain in force.
+Read [the pinned engineering standards](generated/CODING_STANDARDS.md) before
+changing Java. Their backend-module placeholder means `agiledancers-be` here.
+Frontend conventions remain in README.md and agiledancers-fe.
 
-## Scope and authority
+The existing maintainer-approved exception for Group's eight-parameter canonical
+constructor remains in `tooling/standards/waivers.tsv`. No new waiver is introduced
+by S19. For reviews also read [the local companion](docs/backend-review.md).
 
-- Cover handwritten production and test Java in `agiledancers-be`. Exclude
-  generated code. Dependency injection and production architecture rules apply
-  where relevant. Frontend and Java helpers outside the backend are out of scope.
-- [Java coding guidelines](https://www.geeksforgeeks.org/java/coding-guidelines-in-java/)
-  supplied source material. Only the rules adopted in this local document apply;
-  changes to the article do not change project policy.
-- The project's pinned Palantir formatter wins formatting conflicts, including
-  comment layout. S8 remains responsible for formatter integration.
-- Do not adopt unrelated static-analysis rule bundles.
-
-## Java conventions
-
-- Types use UpperCamelCase; methods and variables use lowerCamelCase; constants
-  use UPPER_SNAKE_CASE; package names are lowercase.
-- One top-level type per file; explicit member visibility; `@Override` on
-  overriding methods. Do not invent visibility modifiers where Java forbids them.
-- Opening braces stay on the declaration/control-statement line. All `if`, `for`
-  and `while` bodies require braces, including enhanced for and do/while bodies.
-- No wildcard imports. Static imports are allowed only in test classes.
-- Comments explain intent or constraints. Document public contracts with Javadoc
-  where their meaning is not clear from the declaration; do not require boilerplate
-  documentation for every accessor.
-- Block comments use the following layout, subject to Palantir formatting:
-
-  ```java
-  /*
-      This is an example of a block comment.
-      It may have more than one line.
-  */
-  ```
-- Prefer records for immutable data carriers. Classes are allowed when mutation,
-  framework requirements or inheritance make records unsuitable. Preserve API and
-  serialization behavior. Record immutability is shallow: protect mutable
-  components appropriately.
-- Require `final` for parameters, local variables and fields wherever they can
-  remain assigned once, including loop variables and catch parameters where Java
-  permits it. Field finality must remain compatible with framework injection and
-  lifecycle requirements. Permit reassignment when the algorithm needs it; do not
-  introduce artificial holder objects to avoid reassignment. This rule does not
-  require final classes or methods.
-- Use explicit types unless the initializer visibly identifies the type. `var` is
-  allowed with `new School(...)` or an explicit cast, but not for method results,
-  literals or other inferred expressions. For example,
-  `final var school = new School(...)` is allowed, while a repository result uses
-  `final School school = repository.find(id)`. Borderline cases require review.
-- No additional member-ordering or line-width policy beyond Palantir.
-
-## Metrics
-
-Targets guide development. Review signals require assessment, not automatic
-failure. Blocking limits fail verification. Strict inequalities matter: a value
-exactly at a blocking limit passes.
-
-| Metric | Target | Review signal | Blocking limit |
-| --- | ---: | ---: | ---: |
-| Cyclomatic complexity per method/constructor | ≤ 5 | > 7 | > 10 |
-| Cognitive complexity per method/constructor | ≤ 10 | > 10 | > 15 |
-| Method/constructor length, code lines | ≤ 20 | > 30 | > 50 |
-| Parameters per method | ≤ 3 | > 4 | > 5 |
-| Parameters per explicitly written constructor | ≤ 4 | > 5 | > 7 |
-| Injected dependencies per class | ≤ 4 | > 5 | > 7 |
-| Fan-out per class, unique used types | ≤ 10 | > 15 | Review only |
-| Own superclass depth, excluding Object | ≤ 1 | > 2 | > 3 |
-| Control-flow nesting | ≤ 2 | > 3 | > 4 |
-| Production duplicated lines density | ≤ 1% | > 1% | > 3% |
-| Class length, code lines | ≤ 200 | > 300 | > 500 |
-| Declared public methods per class, excluding trivial accessors | ≤ 10 | > 15 | Review only |
-
-### Measurement definitions
-
-- Use the pinned PMD algorithms as authoritative for cyclomatic and cognitive
-  complexity. Document their exact configuration, including switch and boolean
-  treatment. Do not accidentally introduce a class-level aggregate complexity gate.
-- Measure each method, constructor and explicitly written record constructor
-  independently. Lambda bodies contribute to their enclosing executable;
-  methods in nested/local classes are separate executables.
-- Parameter limits exclude implicit record constructors and generated members.
-  Record component counts remain a design review concern.
-- Length means physical source lines after Palantir formatting, excluding blank
-  and comment-only lines. Declaration and brace-only lines count; a line containing
-  both code and comments counts. Do not substitute statement counts or NCSS.
-  Measure nested types separately and exclude them from enclosing class length.
-- Count distinct injected collaborators by resolved type and qualifier. Include
-  constructor, field, setter, inherited and implicit constructor injection.
-  Repeated injection of the same type and qualifier counts once; differently
-  qualified instances of the same type count separately.
-- Fan-out counts distinct explicitly referenced resolved types, including JDK and
-  framework types. Exclude primitives, the class itself and generated references.
-- Inheritance depth counts project-owned superclass layers; exclude Object,
-  interfaces and external framework ancestry.
-- Nesting combines `if`, loops, `switch` and `catch`, with the first structure at
-  depth one. An `else if` chain stays at one level. `else`, `try` and `finally`
-  add no level themselves. Lambdas retain surrounding depth; methods in nested
-  classes start fresh.
-- Public-method counts include explicitly declared public instance and static
-  methods; exclude constructors, inherited methods and trivial accessors. A
-  trivial accessor only reads or assigns its corresponding field, with no
-  validation, branching or other work.
-- Duplication limits apply only to production code. Duplication in tests is allowed
-  and has no target, review signal or blocking limit.
-- Detect production clones with CPD, minimum 100 tokens, without ignoring
-  identifier or literal differences. Density is
-  `100 × distinct duplicated code-line locations / all production code-line locations`.
-  Exclude blank/comment-only lines from numerator and denominator. Count every
-  occurrence, including the first; merge overlapping ranges to count each source
-  line once. This project metric need not equal a future Sonar metric.
-
-## Enforcement and developer workflow
-
-- Use explicitly pinned Java-25-compatible Checkstyle and PMD/CPD versions.
-  Retain ArchUnit for architecture checks and add small targeted custom checks
-  where standard rules cannot accurately express the agreed semantics.
-- Automate every blocking metric and explicit rule where reliable checking is
-  available. Identify rules requiring manual review explicitly; do not claim
-  they are automated. Review signals must appear in reports even when builds pass.
-- Run standards checks during `mvn verify`; provide documented standalone commands.
-  Ordinary compile/test commands retain the current S8 formatting behavior.
-- Standards checks report violations without rewriting code. CI passes these
-  checks before image publication. Parser failures or unsupported Java constructs
-  fail with the affected path and actionable diagnostics, rather than being skipped.
-- Add a root AGENTS.md instruction requiring agents to read CODING_STANDARDS.md
-  before changing backend Java. Project review instructions must explicitly cover
-  manual rules, review signals in changed code and approved waivers, without
-  repeating checks already enforced by tooling.
-- Keep upstream skill files unchanged. Put project-specific code-review guidance
-  in a companion file referenced by project instructions and used alongside
-  `skills/code-review/SKILL.md`.
-- Waivers must be explicit, narrowly scoped and carry a recorded reason alongside
-  code or configuration. Agents need maintainer agreement before introducing one.
-  No blanket suppressions, exclusions of difficult files or weakened thresholds
-  merely to make verification pass.
-
-## Coverage
-
-- Require at least 80% backend line coverage across handwritten production code
-  for the module as a whole, not separately per class or package. Compare the
-  unrounded percentage against 80%.
-- Local `mvn verify` must reach 80% using backend unit/integration tests alone.
-  This intentionally tightens the original combined-tests-only requirement.
-- CI additionally instruments the backend exercised by Playwright, merges that
-  coverage with backend unit/integration coverage and gates the combined result.
-  The Playwright contribution need not separately reach 80%.
-- Exclude generated code only; do not broadly exclude DTOs, configuration or
-  difficult code. Publish line and branch coverage reports; branch coverage has
-  no agreed blocking percentage.
-- PIT measures mutation-test effectiveness, not line coverage, and is outside
-  S7's required implementation. Configuring Sonar in the pipeline remains out of
-  scope for S14. FindBugs/SpotBugs is not an additional required check suite.
-
-
-## Implemented checks and manual review
-
-Checkstyle **12.3.1**, PMD/CPD **7.28.0**, and JaCoCo **0.8.14** are pinned.
-`tooling/standards/checkstyle.xml` selects individual naming, structure, import and brace checks; no general analysis bundle is enabled.
-`tooling/standards/src/main/java/Standards.java` supplies the targeted measurements.
-ArchUnit remains in the backend test suite for architectural boundaries.
-
-PMD uses Java 25, the running JDK's `jrt-fs.jar`, compiled backend classes and the
-resolved test dependency classpath. Cyclomatic complexity uses PMD's default
-options: boolean paths count, assertions do not. Decisions include if/loops,
-catch, ternary and throw; non-default switch alternatives count individually,
-including comma-separated labels. There is no aggregate class-complexity gate.
-Cognitive complexity uses PMD's boolean-operation sequences, nesting, switch,
-recursion and flow rules. The scoped visitors retain those algorithms while
-including lambdas in their enclosing executable and excluding nested/local type
-bodies, whose methods are measured independently. Compact record constructors
-use the same visitors and start with cyclomatic complexity one.
-
-Custom checks measure physical code lines from regular parser tokens, including
-brace/declaration lines and mixed code/comment lines. They count multiline literal
-lines while excluding physically blank lines. Class length excludes nested-type
-tokens, preserving lines shared with enclosing code. Other custom measurements
-implement the definitions above: nesting, resolved type fan-out, project-owned
-superclass depth, public non-accessor methods, and injected collaborators.
-Injection includes inherited fields/setters, explicit `@Inject` constructors,
-single constructors on bean classes, records' implicit canonical constructors,
-and Lombok required/all-argument constructor injection. Qualifier keys use resolved
-annotation names and values, including defaults; repeat sites are deduplicated.
-The CPD configuration preserves identifiers/literals, uses 100 tokens and disables
-skip blocks. Its line-location union counts overlapping occurrences only once.
-
-Checkstyle and targeted checks enforce import/brace/naming/visibility rules,
-`@Override`, visible constructor/cast/new-array `var` initializer forms, final parameters, locals (including
-loops/catches and lambdas) and initialized fields. PMD's three selected finality
-rules additionally cover control-flow assignment and private constructor-initialized
-fields. Framework/lifecycle requirements, generated Lombok setters, and external
-writes to public/protected fields need review before changing field finality.
-No tool can infer whether a comment explains intent, whether a public contract
-needs Javadoc, whether a record is appropriate, or whether mutable components are
-sufficiently protected. These are **manual rules**, as are ambiguous type inference
-and architecture/DI design decisions. Review all `DESIGN` record-component entries
-and `REVIEW` signals, even when a build passes, using `docs/backend-review.md`.
-
-Reports never rewrite Java. Formatter application remains S8's separate validate
-execution. Generated output under `target` and generated source directories are
-outside the handwritten `src/main/java` and `src/test/java` scope. No maintained
-file, DTO, configuration class or package is excluded from standards or coverage.
-JaCoCo filters compiler/Lombok-generated members; no handwritten-code exclusions
-are configured. Line and branch results are published, with only lines gated.
-
-Exact metric waivers live in `tooling/standards/waivers.tsv`; each records a metric,
-fully resolved executable signature (or class), exact retained value and the
-maintainer agreement/reason. No wildcard waivers are allowed, and a changed value
-fails again. A waived blocking result remains visible as `WAIVER`. PMD suppression
-annotations/comments cannot silently waive a rule. The only approved waiver is the eight-parameter `Group` canonical constructor,
-which preserves its JSON contract while defensively copying both lists. Adding a waiver always requires maintainer agreement.
-
-## Commands and reports
-
-Run from the root with JDK 25:
-
-```sh
-mvn -Dformat.mode=check clean verify
-# Prepare standalone analysis without running tests:
-mvn -pl agiledancers-be test-compile dependency:build-classpath@standards-classpath
-mvn -f tooling/standards/pom.xml test exec:java
-# Exact local coverage gate after a test/report build:
-java tooling/coverage/Coverage.java agiledancers-be/target/site/jacoco/jacoco.xml
-```
-
-`verify` runs backend tests, builds resolved analysis inputs, generates JaCoCo
-reports, runs checker regression tests and standards analysis, then gates exact
-module-wide line coverage. `compile` and `test` retain existing formatting behavior
-and do not run the verify-only standards checks. Standalone analysis requires its
-classpath preparation; unresolved types fail with the path and preparation advice.
-
-Full metrics and findings: `agiledancers-be/target/standards/report.txt`.
-Checker regression results: `tooling/standards/target/surefire-reports`.
-Coverage HTML/XML/CSV: `agiledancers-be/target/site/jacoco` (local backend tests)
-and `agiledancers-be/target/site/jacoco-combined` (merged browser contribution).
-The gate compares integer line counts (`5 * covered >= 4 * total`), rejecting an
-empty report and percentages that would round up to 80%.
-
-CI first passes local verify. It mounts the pinned JaCoCo agent into its disposable
-backend test container, exposes the agent only on the isolated Docker network,
-and uses the pinned CLI to dump `target/playwright.exec` after Playwright. A missing
-or empty dump fails. The following commands merge both datasets and gate the result
-before the verified-commit marker can authorize publication:
-
-```sh
-mvn -pl agiledancers-be jacoco:merge@combined jacoco:report@combined-report exec:exec@combined-coverage
-```
-
-CI retains both coverage reports, execution data, standards findings and regression
-results with its usual diagnostics artifacts. The agent is mounted only for tests;
-published images contain no agent. PIT and Sonar configuration remain outside S7.
-See `specs/S7-validation.md` for migration evidence and retained-signal assessment.
+Validation evidence: [S7](docs/validation/S7-validation.md).

Dockerfile

@@ -2,11 +2,17 @@ FROM maven:3.9-eclipse-temurin-25 AS build
 WORKDIR /workspace
 COPY pom.xml ./
 COPY .mvn .mvn
+COPY generated generated
 COPY tooling tooling
-COPY ci ci
+COPY engineering.properties engineering.properties
 COPY agiledancers-be/pom.xml agiledancers-be/pom.xml
 COPY agiledancers-be/src agiledancers-be/src
-RUN mvn -B -ntp clean verify
+# Source builds run the same PostgreSQL tests as local/CI verification.
+# Supply connection configuration as BuildKit secrets, which are not retained in image layers.
+RUN --mount=type=secret,id=database_url,env=QUARKUS_DATASOURCE_JDBC_URL,required=true \
+    --mount=type=secret,id=database_user,env=QUARKUS_DATASOURCE_USERNAME,required=true \
+    --mount=type=secret,id=database_password,env=QUARKUS_DATASOURCE_PASSWORD,required=true \
+    mvn -B -ntp clean verify
 
 FROM eclipse-temurin:25-jre AS runtime
 WORKDIR /app

README.md

@@ -1,3 +1,18 @@
+# Landscape and shared engineering
+
+Architecture decisions, specifications and project onboarding are maintained in
+[landscape](http://192.168.2.28:3000/wanjakrah/landscape). Shared agent skills are maintained in landscape/skills/. Reusable tooling,
+standards and the project generator are maintained in
+[engineering](http://192.168.2.28:3000/wanjakrah/engineering).
+
+This project commits the engineering version recorded in `engineering.lock.json`
+under `generated/`. Ordinary builds need no other repository checkout. Regenerate
+with `mvn -N -Pregenerate-engineering validate`; CI checks the selected tag and
+commit with `python3 scripts/engineering.py --check`. To upgrade, update both tag
+and commit, follow engineering's UPGRADING.md, regenerate and review the diff.
+Project configuration in `engineering.properties`, workflows and `deploy/` remains
+application-owned. Read CODING_STANDARDS.md and AGENTS.md for project guidance.
+
 # agiledancers
 
 To map dance groups to performance days. The backend runs on Quarkus with Java 25.
@@ -19,14 +34,19 @@ mvn -pl agiledancers-be quarkus:dev
 Run the packaged application after building:
 
 ```sh
+# Set DATABASE_URL, DATABASE_USER and DATABASE_PASSWORD first.
 java -jar agiledancers-be/target/quarkus-app/quarkus-run.jar
 ```
 
-Build and run a Docker container from the repository root (only Docker is required):
+Build a Docker container against an isolated test database (see [connection setup](docs/persistent-storage.md)):
 
 ```sh
-docker build -t agiledancers .
-docker run --rm --name agiledancers -p 8080:8080 agiledancers
+docker build --network=host \
+  --secret id=database_url,env=TEST_DATABASE_URL \
+  --secret id=database_user,env=TEST_DATABASE_USER \
+  --secret id=database_password,env=TEST_DATABASE_PASSWORD -t agiledancers .
+docker run --rm --name agiledancers -p 8080:8080 \
+  -e DATABASE_URL -e DATABASE_USER -e DATABASE_PASSWORD agiledancers
 ```
 
 The Docker build compiles the application and runs the tests in a Maven build stage,
@@ -42,7 +62,13 @@ curl --fail http://localhost:8080/q/health/ready
 Quarkus configuration can be overridden with environment variables, for example
 `docker run --rm -e QUARKUS_HTTP_PORT=9090 -p 9090:9090 agiledancers`.
 
-The REST API uses shared in-memory storage; data is lost when the process stops.
+PostgreSQL stores all school data, planning state and the latest scheduling run
+through JPA/Hibernate ORM. Persistence entities remain in the repository layer.
+Flyway initializes and versions the schema. Production requires `DATABASE_URL`
+(a JDBC PostgreSQL URL), `DATABASE_USER` and `DATABASE_PASSWORD`; missing credentials,
+connection failures and migration failures prevent startup. See
+[database setup and transition](docs/persistent-storage.md) before replacing an
+in-memory release: export every school before stopping it.
 
 Architecture checks run with the normal test suite, or separately with:
 
@@ -56,7 +82,7 @@ mvn -pl agiledancers-be -Dtest=ArchitectureTest test
 | --- | --- | --- |
 | `model` | Domain entities and specifications | Model |
 | `service` | Application use cases and future ports | Model, repositories |
-| `repository` | Current in-memory persistence | Model |
+| `repository` | JPA/Hibernate entities, repositories and transaction boundaries | Model |
 | `rest` | Future REST services | Services, model |
 | `solver` | Future OR-Tools calculations | Services (ports), model |
 
@@ -83,7 +109,8 @@ the solver live in `model.scheduling`. Each group requirement combines its group
 ID and appearance count in one record.
 
 `service.port.SchedulingEngine` is the application-owned interface for solving a
-scheduling problem. `SchedulingService` calls this interface; dependency injection
+scheduling problem. `SchedulingRuns` calls this interface for background runs;
+`SchedulingService` retains the synchronous service entry point. Dependency injection
 supplies `solver.OrToolsSchedulingEngine`. The port accepts and returns domain
 types, so neither the caller nor the contract depends on OR-Tools or the concrete
 school-management service. Architecture tests enforce the port's location and
@@ -160,11 +187,23 @@ dayparts; preschool groups once; showcases every daypart. See
 [show-scheduling-rules.md](show-scheduling-rules.md) for the full hard constraints,
 coach exceptions, ordering and optimization rules.
 
-`POST /api/dance-schools/{schoolId}/shows/{showId}/schedule` generates an ordered
-draft using OR-Tools with a total thirty-minute time limit. A feasible result is
-accepted without claiming optimality. Concurrent runs and stale results return
-`409`; failures retain existing assignments. Development and production proxies
-allow 31 minutes.
+`POST /api/dance-schools/{schoolId}/shows/{showId}/schedule` returns `202` with a
+run identifier and starts an ordered draft calculation in the background using
+OR-Tools with a total thirty-minute time limit. Duplicate starts for the same
+show return `409`; different shows may run concurrently. A feasible result is
+accepted without claiming optimality. Stale results and failures retain existing
+assignments and appear as distinct terminal run states.
+
+`GET .../shows/{showId}/schedule` returns the latest run (`204` if none exists).
+`GET /api/scheduling/events` streams SSE JSON objects containing a `runs` snapshot
+on connection and changes, or `runs: null` as a fifteen-second heartbeat. Clients
+recover current state on reconnection rather than requiring event replay. The
+production proxy disables buffering. The UI shows phase, elapsed time, solution
+discovery and final objective scores, and reports completion in an application-wide
+snackbar. Reloading recovers the latest state without replaying old notifications.
+The latest run and saved assignments survive restart. Startup marks formerly
+running calculations `INTERRUPTED`, preserves the previous assignments, and allows
+a new run. Results and successful status commit in one database transaction.
 
 `PUT .../shows/{showId}/assignments` accepts `{"assignments":[[1,2],[3]]}`, an
 ordered list of group IDs per daypart. Incomplete or invalid drafts can be saved;
@@ -269,13 +308,13 @@ for the current operational status.
 Production releases and rollback use separate manual Gitea workflows. See the
 [deployment runbook](docs/production-deployment.md) for Synology provisioning,
 semantic version tags, release/retry/rollback and the accepted data-loss limitation
-until S16, and [S6 evidence](docs/s6-validation.md) for deployment readiness.
+during the one-time transition from an in-memory release, and [S6 evidence](docs/s6-validation.md) for deployment readiness.
 
 ### Java formatting (S8)
 
 Maven is the authoritative formatting path. The root build runs the actual
 Palantir Java Format **2.101.0**, Palantir style, through a custom OpenRewrite
-**8.63.4** text recipe in `tooling/format/Format.java`. The pinned
+**8.63.4** text recipe in `generated/tooling/format/Format.java`. The pinned
 `exec-maven-plugin` **3.6.3** launches that helper with JDK 25. Native import
 ordering and unused-import removal are enabled; extra Javadoc formatting is off.
 No OpenRewrite AutoFormat or additional refactoring recipes run.
@@ -320,9 +359,9 @@ format-on-save must not override Maven's result. Other editors can invoke the
 standalone Maven apply command as an external tool.
 
 Verification and measurements are recorded in
-[the S8 evidence](specs/S8-formatting-evidence.md). Reproduce the isolated failure,
+[the S8 evidence](docs/validation/S8-formatting-evidence.md). Reproduce the isolated failure,
 UTF-8, import, cache and idempotence checks with
-`python3 tooling/format/test.py`, and the sequential end-to-end build measurements
+the formatter integration test in engineering (`python3 tests/format_integration.py`), and the sequential end-to-end build measurements
 with `python3 tooling/format/benchmark.py` (requires the ordinary backend test
 prerequisites). Results are written under `target/`.
 
@@ -333,4 +372,19 @@ It defines the agreed rules, exact metric limits, manual review duties, pinned
 analysis tools, coverage policy and standalone commands. `mvn verify` runs standards
 checks and requires at least 80% module-wide backend line coverage. CI also collects
 and merges coverage from Playwright before publication. Reports are retained with
-CI diagnostics. See [S7 validation](specs/S7-validation.md) for current migration status.
+CI diagnostics. See [S7 validation](docs/validation/S7-validation.md) for current migration status.
+
+
+Existing-school mutations require `X-School-Revision` with the revision loaded by
+the editor. `GET /api/dance-schools/{id}/data` returns the school and all its editor
+data from one consistent snapshot; `school.revision` identifies that snapshot.
+Missing or stale revisions receive `409` with a reload instruction. The import
+preview returns `existingRevision` for replacement confirmation. Creation of a
+new school does not need a revision. The frontend never automatically retries a
+conflicting edit with a newer revision.
+
+
+Domain-to-view projection is generated by MapStruct in `rest.mapping.DomainViewMapper`.
+It is a CDI bean with `unmappedTargetPolicy = ERROR`, so unmatched target fields fail
+compilation. REST resources supply calculated validation results explicitly. The
+entity-to-domain graph mappings remain handwritten in the repository layer.

agiledancers-be/pom.xml

@@ -14,6 +14,11 @@
     <packaging>jar</packaging>
 
     <dependencies>
+        <dependency><groupId>org.mapstruct</groupId><artifactId>mapstruct</artifactId><version>${mapstruct.version}</version></dependency>
+        <dependency><groupId>io.quarkus</groupId><artifactId>quarkus-hibernate-orm</artifactId></dependency>
+        <dependency><groupId>io.quarkus</groupId><artifactId>quarkus-jdbc-postgresql</artifactId></dependency>
+        <dependency><groupId>io.quarkus</groupId><artifactId>quarkus-flyway</artifactId></dependency>
+        <dependency><groupId>org.flywaydb</groupId><artifactId>flyway-database-postgresql</artifactId></dependency>
         <dependency>
             <groupId>io.quarkus</groupId>
             <artifactId>quarkus-rest-jackson</artifactId>
@@ -63,6 +68,16 @@
 
     <build>
         <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <annotationProcessorPaths combine.children="append">
+                        <path><groupId>org.mapstruct</groupId><artifactId>mapstruct-processor</artifactId><version>${mapstruct.version}</version></path>
+                        <path><groupId>org.projectlombok</groupId><artifactId>lombok-mapstruct-binding</artifactId><version>${lombok-mapstruct-binding.version}</version></path>
+                    </annotationProcessorPaths>
+                    <compilerArgs><arg>-Amapstruct.suppressGeneratorTimestamp=true</arg></compilerArgs>
+                </configuration>
+            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId><artifactId>maven-dependency-plugin</artifactId><version>3.8.1</version>
                 <executions><execution><id>standards-classpath</id><phase>prepare-package</phase><goals><goal>build-classpath</goal></goals>
@@ -70,7 +85,7 @@
                 </execution>
                 <execution><id>coverage-tools</id><phase>prepare-package</phase><goals><goal>copy</goal></goals>
                     <configuration><artifactItems>
-                        <artifactItem><groupId>org.jacoco</groupId><artifactId>org.jacoco.agent</artifactId><version>0.8.14</version><classifier>runtime</classifier><destFileName>agent.jar</destFileName></artifactItem>
+                        <artifactItem><groupId>org.jacoco</groupId><artifactId>org.jacoco.agent</artifactId><version>0.8.16</version><classifier>runtime</classifier><destFileName>agent.jar</destFileName></artifactItem>
                         <artifactItem><groupId>org.jacoco</groupId><artifactId>org.jacoco.cli</artifactId><version>0.8.14</version><classifier>nodeps</classifier><destFileName>cli.jar</destFileName></artifactItem>
                     </artifactItems><outputDirectory>${project.build.directory}/coverage-tools</outputDirectory></configuration>
                 </execution></executions>
@@ -82,26 +97,26 @@
                         <executable>${maven.home}/bin/mvn</executable>
                         <workingDirectory>${maven.multiModuleProjectDirectory}</workingDirectory>
                         <arguments><argument>-B</argument><argument>-ntp</argument><argument>-f</argument>
-                            <argument>${maven.multiModuleProjectDirectory}/tooling/standards/pom.xml</argument>
+                            <argument>${maven.multiModuleProjectDirectory}/generated/tooling/standards/pom.xml</argument>
                             <argument>test</argument><argument>exec:java</argument>
                         </arguments>
                     </configuration>
                 </execution>
                 <execution><id>coverage</id><phase>verify</phase><goals><goal>exec</goal></goals>
                     <configuration><executable>${java.home}/bin/java</executable><arguments>
-                        <argument>${maven.multiModuleProjectDirectory}/tooling/coverage/Coverage.java</argument>
+                        <argument>${maven.multiModuleProjectDirectory}/generated/tooling/coverage/Coverage.java</argument>
                         <argument>${project.build.directory}/site/jacoco/jacoco.xml</argument>
                     </arguments></configuration>
                 </execution>
                 <execution><id>combined-coverage</id><phase>none</phase><goals><goal>exec</goal></goals>
                     <configuration><executable>${java.home}/bin/java</executable><arguments>
-                        <argument>${maven.multiModuleProjectDirectory}/tooling/coverage/Coverage.java</argument>
+                        <argument>${maven.multiModuleProjectDirectory}/generated/tooling/coverage/Coverage.java</argument>
                         <argument>${project.build.directory}/site/jacoco-combined/jacoco.xml</argument>
                     </arguments></configuration>
                 </execution></executions>
             </plugin>
             <plugin>
-                <groupId>org.jacoco</groupId><artifactId>jacoco-maven-plugin</artifactId><version>0.8.14</version>
+                <groupId>org.jacoco</groupId><artifactId>jacoco-maven-plugin</artifactId><version>0.8.16</version>
                 <executions>
                     <execution><id>agent</id><goals><goal>prepare-agent</goal></goals><configuration>
                         <exclClassLoaders>*QuarkusClassLoader</exclClassLoaders><destFile>${project.build.directory}/jacoco.exec</destFile><append>true</append>

agiledancers-be/src/main/java/nl/agilecc/agiledancers/model/DanceSchool.java

@@ -20,6 +20,9 @@ public class DanceSchool extends AbstractEntity {
     @Setter
     private String name;
 
+    @Setter
+    private long revision;
+
     @Builder.Default
     private final Set<Dancer> dancers = new LinkedHashSet<>();
 

agiledancers-be/src/main/java/nl/agilecc/agiledancers/model/scheduling/SchedulingFailureKind.java

@@ -0,0 +1,7 @@
+package nl.agilecc.agiledancers.model.scheduling;
+
+public enum SchedulingFailureKind {
+    INFEASIBLE,
+    NO_SOLUTION,
+    SOLVER_FAILED
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/model/scheduling/SchedulingPhase.java

@@ -0,0 +1,8 @@
+package nl.agilecc.agiledancers.model.scheduling;
+
+public enum SchedulingPhase {
+    PREPARING,
+    ATTENDANCE,
+    SPREAD,
+    VARIETY
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/model/scheduling/SchedulingProgress.java

@@ -0,0 +1,4 @@
+package nl.agilecc.agiledancers.model.scheduling;
+
+/** Progress is observational; intermediate assignments are never published or applied. */
+public record SchedulingProgress(SchedulingPhase phase, boolean feasible) {}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/model/scheduling/SchedulingRun.java

@@ -0,0 +1,60 @@
+package nl.agilecc.agiledancers.model.scheduling;
+
+import java.time.Instant;
+import java.util.UUID;
+
+/** Latest immutable state for one show's calculation; runId identifies notifications across reconnects. */
+public record SchedulingRun(
+        UUID runId,
+        long schoolId,
+        long showId,
+        String showName,
+        Instant startedAt,
+        Instant finishedAt,
+        SchedulingState state,
+        SchedulingProgress progress,
+        String message,
+        SchedulingSummary summary) {
+    public static SchedulingRun started(final long schoolId, final long showId, final String name) {
+        return new SchedulingRun(
+                UUID.randomUUID(),
+                schoolId,
+                showId,
+                name,
+                Instant.now().truncatedTo(java.time.temporal.ChronoUnit.MICROS),
+                null,
+                SchedulingState.RUNNING,
+                new SchedulingProgress(SchedulingPhase.PREPARING, false),
+                "Berekening gestart.",
+                null);
+    }
+
+    public SchedulingRun progressed(final SchedulingProgress update) {
+        return new SchedulingRun(
+                runId,
+                schoolId,
+                showId,
+                showName,
+                startedAt,
+                null,
+                state,
+                new SchedulingProgress(update.phase(), progress.feasible() || update.feasible()),
+                message,
+                null);
+    }
+
+    public SchedulingRun completed(
+            final SchedulingState outcome, final String explanation, final SchedulingSummary scores) {
+        return new SchedulingRun(
+                runId,
+                schoolId,
+                showId,
+                showName,
+                startedAt,
+                Instant.now().truncatedTo(java.time.temporal.ChronoUnit.MICROS),
+                outcome,
+                new SchedulingProgress(progress.phase(), progress.feasible() || scores != null),
+                explanation,
+                scores);
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/model/scheduling/SchedulingState.java

@@ -0,0 +1,13 @@
+package nl.agilecc.agiledancers.model.scheduling;
+
+public enum SchedulingState {
+    RUNNING,
+    INTERRUPTED,
+    OPTIMAL,
+    VALID,
+    STALE,
+    INVALID_INPUT,
+    INFEASIBLE,
+    NO_SOLUTION,
+    SOLVER_FAILED
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/model/scheduling/SchedulingSummary.java

@@ -0,0 +1,59 @@
+package nl.agilecc.agiledancers.model.scheduling;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/** Scores match the solver objectives; lower values are better. */
+public record SchedulingSummary(long attendanceExcess, int performanceSpread, long varietyPenalty) {
+    public static SchedulingSummary of(final SchedulingInput input, final SchedulingResult result) {
+        final List<List<Long>> parts = result.assignments();
+        final Map<Long, GroupRequirement> groups = new HashMap<>();
+        input.groups().forEach((final GroupRequirement group) -> groups.put(group.groupId(), group));
+        final int min = parts.stream().mapToInt(List::size).min().orElse(0);
+        final int max = parts.stream().mapToInt(List::size).max().orElse(0);
+        return new SchedulingSummary(attendance(input, parts), max - min, variety(parts, groups));
+    }
+
+    private static long attendance(final SchedulingInput input, final List<List<Long>> parts) {
+        final Set<Long> showcases = new HashSet<>();
+        final Map<Long, Set<Integer>> attendance = new HashMap<>();
+        for (final GroupRequirement group : input.groups()) {
+            if (group.showcase()) {
+                showcases.addAll(group.dancerIds());
+            } else {
+                recordAttendance(group, parts, attendance);
+            }
+        }
+        showcases.removeAll(input.coachDancerIds());
+        return showcases.stream()
+                .mapToLong((final Long dancer) ->
+                        Math.max(0, attendance.getOrDefault(dancer, Set.of()).size() - input.preferredDayParts()))
+                .sum();
+    }
+
+    private static void recordAttendance(
+            final GroupRequirement group, final List<List<Long>> parts, final Map<Long, Set<Integer>> attendance) {
+        for (int part = 0; part < parts.size(); part++) {
+            if (parts.get(part).contains(group.groupId())) {
+                for (final long dancer : group.dancerIds()) {
+                    attendance
+                            .computeIfAbsent(dancer, (final Long id) -> new HashSet<>())
+                            .add(part);
+                }
+            }
+        }
+    }
+
+    private static long variety(final List<List<Long>> parts, final Map<Long, GroupRequirement> groups) {
+        long penalty = 0;
+        for (final List<Long> part : parts) {
+            for (int index = 1; index < part.size(); index++) {
+                penalty += VarietyScore.penalty(groups.get(part.get(index - 1)), groups.get(part.get(index)));
+            }
+        }
+        return penalty;
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/AbstractRepository.java

@@ -7,11 +7,19 @@ import nl.agilecc.agiledancers.model.AbstractEntity;
 
 public abstract class AbstractRepository<T extends AbstractEntity> {
     private long sequence = 0L;
+    private java.util.function.LongSupplier identifiers;
 
     protected final Map<Long, T> entities = new LinkedHashMap<>();
 
     public long nextId() {
-        return sequence++;
+        return identifiers == null ? sequence++ : identifiers.getAsLong();
+    }
+
+    /** Replaces detached transaction state; production identifiers come from PostgreSQL. */
+    public void load(final java.util.Collection<T> values, final java.util.function.LongSupplier identifiers) {
+        entities.clear();
+        values.forEach((final T entity) -> entities.put(entity.getId(), entity));
+        this.identifiers = identifiers;
     }
 
     public T add(final T entity) {

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/Database.java

@@ -0,0 +1,113 @@
+package nl.agilecc.agiledancers.repository;
+
+import jakarta.inject.Inject;
+import jakarta.inject.Singleton;
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.LockModeType;
+import jakarta.persistence.OptimisticLockException;
+import jakarta.persistence.PersistenceException;
+import jakarta.transaction.Status;
+import jakarta.transaction.TransactionManager;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Callable;
+import nl.agilecc.agiledancers.repository.entity.EntityIdentifiers;
+
+/** Owns short JTA units of work; Hibernate flushes before commit and publication follows durable commit. */
+@Singleton
+public class Database {
+    private final EntityManager entities;
+    private final TransactionManager manager;
+    private final ThreadLocal<List<Runnable>> committed = new ThreadLocal<>();
+    private final ThreadLocal<List<Runnable>> rolledBack = new ThreadLocal<>();
+
+    @Inject
+    public Database(final EntityManager entities, final TransactionManager manager) {
+        this.entities = entities;
+        this.manager = manager;
+    }
+
+    /**
+     * Runs work in a new transaction, or joins the current JTA transaction. Callback registration is supported only
+     * inside transactions started by this instance. Commit callbacks run in registration order after durable commit;
+     * their exceptions propagate to the caller without rolling back committed work or running remaining callbacks.
+     * Rollback callbacks run before the original failure is rethrown; a callback exception replaces that failure.
+     */
+    public <T> T transaction(final Callable<T> work) throws Exception {
+        try {
+            if (manager.getStatus() != Status.STATUS_NO_TRANSACTION) {
+                return work.call();
+            }
+            return outerTransaction(work);
+        } catch (final OptimisticLockException failure) {
+            throw new RevisionConflictException();
+        } catch (final PersistenceException
+                | jakarta.transaction.SystemException
+                | jakarta.transaction.RollbackException
+                | jakarta.transaction.HeuristicMixedException
+                | jakarta.transaction.HeuristicRollbackException
+                | jakarta.transaction.NotSupportedException failure) {
+            if (optimisticConflict(failure)) {
+                throw new RevisionConflictException();
+            }
+            System.getLogger(Database.class.getName())
+                    .log(System.Logger.Level.WARNING, "JPA transaction failed", failure);
+            throw new StorageException(failure);
+        }
+    }
+
+    private static boolean optimisticConflict(final Throwable failure) {
+        for (Throwable cause = failure; cause != null; cause = cause.getCause()) {
+            if (cause instanceof OptimisticLockException) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private <T> T outerTransaction(final Callable<T> work) throws Exception {
+        final List<Runnable> publications = new ArrayList<>();
+        manager.begin();
+        committed.set(publications);
+        rolledBack.set(new ArrayList<>());
+        final T result;
+        try {
+            result = work.call();
+            manager.commit();
+        } catch (final Exception | Error failure) {
+            rollback(failure);
+            rolledBack.get().forEach(Runnable::run);
+            throw failure;
+        } finally {
+            committed.remove();
+            rolledBack.remove();
+        }
+        publications.forEach(Runnable::run);
+        return result;
+    }
+
+    private void rollback(final Throwable failure) {
+        try {
+            if (manager.getStatus() != Status.STATUS_NO_TRANSACTION) {
+                manager.rollback();
+            }
+        } catch (final jakarta.transaction.SystemException rollbackFailure) {
+            failure.addSuppressed(rollbackFailure);
+        }
+    }
+
+    /** Registers a callback on this thread's transaction owned by this instance; see {@link #transaction(Callable)}. */
+    public void afterCommit(final Runnable action) {
+        committed.get().add(action);
+    }
+
+    /** Registers a rollback callback under the same ownership requirement as {@link #afterCommit(Runnable)}. */
+    public void afterRollback(final Runnable action) {
+        rolledBack.get().add(action);
+    }
+
+    public long nextId() {
+        return entities.find(EntityIdentifiers.class, 1, LockModeType.PESSIMISTIC_WRITE)
+                .claim();
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/GroupMapping.java

@@ -0,0 +1,62 @@
+package nl.agilecc.agiledancers.repository;
+
+import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
+import java.util.Map;
+import nl.agilecc.agiledancers.model.Coach;
+import nl.agilecc.agiledancers.model.DanceGroup;
+import nl.agilecc.agiledancers.model.DanceSchool;
+import nl.agilecc.agiledancers.model.Dancer;
+import nl.agilecc.agiledancers.repository.entity.CoachEntity;
+import nl.agilecc.agiledancers.repository.entity.GroupEntity;
+import nl.agilecc.agiledancers.repository.entity.SchoolEntity;
+import nl.agilecc.agiledancers.repository.entity.SchoolMemberId;
+
+public class GroupMapping {
+    public static Map<Long, DanceGroup> groups(
+            final SchoolEntity stored,
+            final DanceSchool school,
+            final Map<Long, Coach> coaches,
+            final Map<Long, Dancer> dancers) {
+        final Map<Long, DanceGroup> result = new LinkedHashMap<>();
+        for (final GroupEntity entity : stored.getGroups()) {
+            final DanceGroup group = DanceGroup.builder()
+                    .category(entity.getCategory())
+                    .type(entity.getType())
+                    .startAge(entity.getStartAge())
+                    .endAge(entity.getEndAge())
+                    .coach(
+                            entity.getCoach() == null
+                                    ? null
+                                    : coaches.get(entity.getCoach().getId().getLocalId()))
+                    .styles(new LinkedHashSet<>(entity.getStyles()))
+                    .build();
+            group.setId(entity.getId().getLocalId());
+            entity.getDancerIds().stream().sorted().forEach((final Long id) -> group.addDancer(dancers.get(id)));
+            school.addDanceGroup(group);
+            result.put(group.getId(), group);
+        }
+        return result;
+    }
+
+    public static GroupEntity group(final SchoolEntity school, final DanceGroup group) {
+        final GroupEntity entity = new GroupEntity();
+        entity.setId(new SchoolMemberId(school.getId(), group.getId()));
+        entity.setSchool(school);
+        entity.setCategory(group.getCategory());
+        entity.setType(group.getType());
+        entity.setStartAge(group.getStartAge());
+        entity.setEndAge(group.getEndAge());
+        if (group.getCoach() != null) {
+            entity.setCoach(school.getCoaches().stream()
+                    .filter((final CoachEntity coach) ->
+                            coach.getId().getLocalId() == group.getCoach().getId())
+                    .findFirst()
+                    .orElseThrow());
+        }
+        entity.setStyles(new LinkedHashSet<>(group.getStyles()));
+        group.getDancers()
+                .forEach((final Dancer dancer) -> entity.getDancerIds().add(dancer.getId()));
+        return entity;
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/PeopleMapping.java

@@ -0,0 +1,70 @@
+package nl.agilecc.agiledancers.repository;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import nl.agilecc.agiledancers.model.Coach;
+import nl.agilecc.agiledancers.model.DanceSchool;
+import nl.agilecc.agiledancers.model.Dancer;
+import nl.agilecc.agiledancers.repository.entity.CoachEntity;
+import nl.agilecc.agiledancers.repository.entity.DancerEntity;
+import nl.agilecc.agiledancers.repository.entity.SchoolEntity;
+import nl.agilecc.agiledancers.repository.entity.SchoolMemberId;
+
+/** Converts people while preserving the shared dancer identity used by coach links. */
+public class PeopleMapping {
+    public static Map<Long, Dancer> dancers(final SchoolEntity stored, final DanceSchool school) {
+        final Map<Long, Dancer> result = new LinkedHashMap<>();
+        for (final DancerEntity person : stored.getDancers()) {
+            final Dancer dancer = Dancer.builder()
+                    .name(person.getName())
+                    .birthDate(person.getBirthDate())
+                    .build();
+            dancer.setId(person.getId().getLocalId());
+            school.addDancer(dancer);
+            result.put(dancer.getId(), dancer);
+        }
+        return result;
+    }
+
+    public static Map<Long, Coach> coaches(
+            final SchoolEntity stored, final DanceSchool school, final Map<Long, Dancer> dancers) {
+        final Map<Long, Coach> result = new LinkedHashMap<>();
+        for (final CoachEntity trainer : stored.getCoaches()) {
+            final Coach coach = Coach.builder()
+                    .name(trainer.getName())
+                    .dancer(
+                            trainer.getDancer() == null
+                                    ? null
+                                    : dancers.get(trainer.getDancer().getId().getLocalId()))
+                    .build();
+            coach.setId(trainer.getId().getLocalId());
+            school.addCoach(coach);
+            result.put(coach.getId(), coach);
+        }
+        return result;
+    }
+
+    public static DancerEntity dancer(final SchoolEntity school, final Dancer dancer) {
+        final DancerEntity entity = new DancerEntity();
+        entity.setId(new SchoolMemberId(school.getId(), dancer.getId()));
+        entity.setSchool(school);
+        entity.setName(dancer.getName());
+        entity.setBirthDate(dancer.getBirthDate());
+        return entity;
+    }
+
+    public static CoachEntity coach(final SchoolEntity school, final Coach coach) {
+        final CoachEntity entity = new CoachEntity();
+        entity.setId(new SchoolMemberId(school.getId(), coach.getId()));
+        entity.setSchool(school);
+        entity.setName(coach.getName());
+        if (coach.getDancer() != null) {
+            entity.setDancer(school.getDancers().stream()
+                    .filter((final DancerEntity dancer) ->
+                            dancer.getId().getLocalId() == coach.getDancer().getId())
+                    .findFirst()
+                    .orElseThrow());
+        }
+        return entity;
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/RevisionConflictException.java

@@ -0,0 +1,8 @@
+package nl.agilecc.agiledancers.repository;
+
+/** An optimistic persistence conflict requires a new editor snapshot, never an automatic retry. */
+public class RevisionConflictException extends RuntimeException {
+    public RevisionConflictException() {
+        super("Deze school is gewijzigd. Herlaad de gegevens en probeer opnieuw.");
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/RunRepository.java

@@ -0,0 +1,78 @@
+package nl.agilecc.agiledancers.repository;
+
+import jakarta.inject.Inject;
+import jakarta.inject.Singleton;
+import jakarta.persistence.EntityManager;
+import java.util.List;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingProgress;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingRun;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingState;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingSummary;
+import nl.agilecc.agiledancers.repository.entity.RunEntity;
+import nl.agilecc.agiledancers.repository.entity.SchoolMemberId;
+
+@Singleton
+public class RunRepository {
+    private final EntityManager entities;
+
+    @Inject
+    public RunRepository(final EntityManager entities) {
+        this.entities = entities;
+    }
+
+    public List<SchedulingRun> load() {
+        return entities
+                .createQuery("from StoredRun run order by run.id.schoolId,run.id.localId", RunEntity.class)
+                .getResultList()
+                .stream()
+                .map(this::read)
+                .toList();
+    }
+
+    public void recover() {
+        load().stream()
+                .filter((final SchedulingRun run) -> run.state() == SchedulingState.RUNNING)
+                .forEach((final SchedulingRun run) -> save(run.completed(
+                        SchedulingState.INTERRUPTED,
+                        "Berekening onderbroken door een backendherstart. Geen nieuw resultaat toegepast; bestaande"
+                                + " indeling behouden. Start de berekening opnieuw.",
+                        null)));
+    }
+
+    public void save(final SchedulingRun run) {
+        final RunEntity entity = new RunEntity();
+        entity.setId(new SchoolMemberId(run.schoolId(), run.showId()));
+        entity.setRunId(run.runId());
+        entity.setShowName(run.showName());
+        entity.setStartedAt(run.startedAt());
+        entity.setFinishedAt(run.finishedAt());
+        entity.setState(run.state());
+        entity.setPhase(run.progress().phase());
+        entity.setFeasible(run.progress().feasible());
+        entity.setMessage(run.message());
+        if (run.summary() != null) {
+            entity.setAttendanceExcess(run.summary().attendanceExcess());
+            entity.setPerformanceSpread(run.summary().performanceSpread());
+            entity.setVarietyPenalty(run.summary().varietyPenalty());
+        }
+        entities.merge(entity);
+    }
+
+    private SchedulingRun read(final RunEntity entity) {
+        final SchedulingSummary summary = entity.getAttendanceExcess() == null
+                ? null
+                : new SchedulingSummary(
+                        entity.getAttendanceExcess(), entity.getPerformanceSpread(), entity.getVarietyPenalty());
+        return new SchedulingRun(
+                entity.getRunId(),
+                entity.getId().getSchoolId(),
+                entity.getId().getLocalId(),
+                entity.getShowName(),
+                entity.getStartedAt(),
+                entity.getFinishedAt(),
+                entity.getState(),
+                new SchedulingProgress(entity.getPhase(), entity.isFeasible()),
+                entity.getMessage(),
+                summary);
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/SchoolReader.java

@@ -0,0 +1,47 @@
+package nl.agilecc.agiledancers.repository;
+
+import jakarta.inject.Inject;
+import jakarta.inject.Singleton;
+import jakarta.persistence.EntityManager;
+import java.util.List;
+import java.util.Map;
+import nl.agilecc.agiledancers.model.Coach;
+import nl.agilecc.agiledancers.model.DanceGroup;
+import nl.agilecc.agiledancers.model.DanceSchool;
+import nl.agilecc.agiledancers.model.Dancer;
+import nl.agilecc.agiledancers.repository.entity.SchoolEntity;
+import nl.agilecc.agiledancers.repository.entity.ShowEntity;
+
+/** Exposes detached domain snapshots, keeping Hibernate sessions and lazy collections inside the adapter. */
+@Singleton
+public class SchoolReader {
+    private final EntityManager entities;
+
+    @Inject
+    public SchoolReader(final EntityManager entities) {
+        this.entities = entities;
+    }
+
+    public List<DanceSchool> load() {
+        return entities
+                .createQuery("from StoredSchool school order by school.id", SchoolEntity.class)
+                .getResultList()
+                .stream()
+                .map(this::school)
+                .toList();
+    }
+
+    private DanceSchool school(final SchoolEntity entity) {
+        final DanceSchool school = DanceSchool.builder()
+                .key(entity.getKey())
+                .name(entity.getName())
+                .revision(entity.getRevision())
+                .build();
+        school.setId(entity.getId());
+        final Map<Long, Dancer> dancers = PeopleMapping.dancers(entity, school);
+        final Map<Long, Coach> coaches = PeopleMapping.coaches(entity, school, dancers);
+        final Map<Long, DanceGroup> groups = GroupMapping.groups(entity, school, coaches, dancers);
+        entity.getShows().forEach((final ShowEntity show) -> school.addShow(ShowMapping.show(show, groups)));
+        return school;
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/SchoolWriter.java

@@ -0,0 +1,82 @@
+package nl.agilecc.agiledancers.repository;
+
+import jakarta.inject.Inject;
+import jakarta.inject.Singleton;
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.LockModeType;
+import java.util.List;
+import nl.agilecc.agiledancers.model.Coach;
+import nl.agilecc.agiledancers.model.DanceGroup;
+import nl.agilecc.agiledancers.model.DanceSchool;
+import nl.agilecc.agiledancers.model.Dancer;
+import nl.agilecc.agiledancers.model.Show;
+import nl.agilecc.agiledancers.repository.entity.RunEntity;
+import nl.agilecc.agiledancers.repository.entity.SchoolEntity;
+
+/** Hibernate merges the aggregate graph and handles child differences, orphan removal and optimistic versioning. */
+@Singleton
+public class SchoolWriter {
+    private final EntityManager entities;
+
+    @Inject
+    public SchoolWriter(final EntityManager entities) {
+        this.entities = entities;
+    }
+
+    public void checkRevision(final long schoolId, final long expected) {
+        final SchoolEntity school = entities.find(SchoolEntity.class, schoolId, LockModeType.OPTIMISTIC);
+        if (school == null || school.getRevision() != expected) {
+            throw new RevisionConflictException();
+        }
+    }
+
+    public void save(final DanceSchool school) {
+        final SchoolEntity existing = entities.find(SchoolEntity.class, school.getId());
+        final SchoolEntity graph = graph(school);
+        if (existing == null) {
+            entities.persist(graph);
+        } else {
+            removeDeletedRuns(school);
+            graph.setRevision(existing.getRevision());
+            graph.setChangeStamp(existing.getChangeStamp() + 1);
+            entities.merge(graph);
+        }
+        entities.flush();
+    }
+
+    private SchoolEntity graph(final DanceSchool school) {
+        final SchoolEntity graph = new SchoolEntity();
+        graph.setId(school.getId());
+        graph.setKey(school.getKey());
+        graph.setName(school.getName());
+        school.getDancers()
+                .forEach((final Dancer dancer) -> graph.getDancers().add(PeopleMapping.dancer(graph, dancer)));
+        school.getCoaches().forEach((final Coach coach) -> graph.getCoaches().add(PeopleMapping.coach(graph, coach)));
+        school.getDanceGroups()
+                .forEach((final DanceGroup group) -> graph.getGroups().add(GroupMapping.group(graph, group)));
+        school.getShows().forEach((final Show show) -> graph.getShows().add(ShowMapping.show(graph, show)));
+        return graph;
+    }
+
+    private void removeDeletedRuns(final DanceSchool school) {
+        final List<Long> shows = school.getShows().stream().map(Show::getId).toList();
+        entities
+                .createQuery("from StoredRun run where run.id.schoolId=:school", RunEntity.class)
+                .setParameter("school", school.getId())
+                .getResultList()
+                .stream()
+                .filter((final RunEntity run) -> !shows.contains(run.getId().getLocalId()))
+                .forEach(entities::remove);
+    }
+
+    public void delete(final long schoolId) {
+        entities.createQuery("from StoredRun run where run.id.schoolId=:school", RunEntity.class)
+                .setParameter("school", schoolId)
+                .getResultList()
+                .forEach(entities::remove);
+        final SchoolEntity school = entities.find(SchoolEntity.class, schoolId);
+        if (school != null) {
+            entities.remove(school);
+        }
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/ShowMapping.java

@@ -0,0 +1,59 @@
+package nl.agilecc.agiledancers.repository;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import nl.agilecc.agiledancers.model.DanceGroup;
+import nl.agilecc.agiledancers.model.DayPart;
+import nl.agilecc.agiledancers.model.Show;
+import nl.agilecc.agiledancers.repository.entity.DayPartEntity;
+import nl.agilecc.agiledancers.repository.entity.DayPartId;
+import nl.agilecc.agiledancers.repository.entity.SchoolEntity;
+import nl.agilecc.agiledancers.repository.entity.SchoolMemberId;
+import nl.agilecc.agiledancers.repository.entity.ShowEntity;
+
+public class ShowMapping {
+    public static Show show(final ShowEntity entity, final Map<Long, DanceGroup> groups) {
+        final Show show = Show.builder()
+                .name(entity.getName())
+                .preferredDayParts(entity.getPreferredDayParts())
+                .finalized(entity.isFinalized())
+                .appearances(Map.copyOf(entity.getAppearances()))
+                .dayParts(entity.getDayParts().stream()
+                        .map((final DayPartEntity part) -> DayPart.builder()
+                                .date(part.getDate())
+                                .type(part.getType())
+                                .danceGroups(part.getGroupIds().stream()
+                                        .map(groups::get)
+                                        .toList())
+                                .build())
+                        .toList())
+                .build();
+        show.setId(entity.getId().getLocalId());
+        return show;
+    }
+
+    public static ShowEntity show(final SchoolEntity school, final Show show) {
+        final ShowEntity entity = new ShowEntity();
+        entity.setId(new SchoolMemberId(school.getId(), show.getId()));
+        entity.setSchool(school);
+        entity.setName(show.getName());
+        entity.setPreferredDayParts(show.getPreferredDayParts());
+        entity.setFinalized(show.isFinalized());
+        entity.setAppearances(new LinkedHashMap<>(show.getAppearances()));
+        for (int index = 0; index < show.getDayParts().size(); index++) {
+            entity.getDayParts().add(part(entity, index, show.getDayParts().get(index)));
+        }
+        return entity;
+    }
+
+    private static DayPartEntity part(final ShowEntity show, final int position, final DayPart part) {
+        final DayPartEntity entity = new DayPartEntity();
+        entity.setId(new DayPartId(show.getId().getSchoolId(), show.getId().getLocalId(), position));
+        entity.setShow(show);
+        entity.setDate(part.getDate());
+        entity.setType(part.getType());
+        part.getDanceGroups()
+                .forEach((final DanceGroup group) -> entity.getGroupIds().add(group.getId()));
+        return entity;
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/StorageException.java

@@ -0,0 +1,8 @@
+package nl.agilecc.agiledancers.repository;
+
+/** Storage failures never authorize an in-memory fallback. */
+public class StorageException extends RuntimeException {
+    public StorageException(final Exception cause) {
+        super("Database niet beschikbaar. De wijziging is niet opgeslagen; herlaad en probeer opnieuw.", cause);
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/CoachEntity.java

@@ -0,0 +1,33 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+@Entity(name = "StoredCoach")
+@Table(name = "coach")
+public class CoachEntity extends SchoolMemberEntity {
+    @Column(nullable = false)
+    private String name;
+
+    // The shared school key is read from the owning row; only the linked member ID is writable.
+    @ManyToOne(
+            fetch = FetchType.LAZY,
+            cascade = {CascadeType.MERGE, CascadeType.PERSIST})
+    @org.hibernate.annotations.JoinColumnsOrFormulas({
+        @org.hibernate.annotations.JoinColumnOrFormula(
+                column = @JoinColumn(name = "dancer_id", referencedColumnName = "id")),
+        @org.hibernate.annotations.JoinColumnOrFormula(
+                formula =
+                        @org.hibernate.annotations.JoinFormula(value = "school_id", referencedColumnName = "school_id"))
+    })
+    private DancerEntity dancer;
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/DancerEntity.java

@@ -0,0 +1,20 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Table;
+import java.time.LocalDate;
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+@Entity(name = "StoredDancer")
+@Table(name = "dancer")
+public class DancerEntity extends SchoolMemberEntity {
+    @Column(nullable = false)
+    private String name;
+
+    @Column(name = "birth_date", nullable = false)
+    private LocalDate birthDate;
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/DayPartEntity.java

@@ -0,0 +1,56 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.CollectionTable;
+import jakarta.persistence.Column;
+import jakarta.persistence.ElementCollection;
+import jakarta.persistence.EmbeddedId;
+import jakarta.persistence.Entity;
+import jakarta.persistence.EnumType;
+import jakarta.persistence.Enumerated;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.JoinColumns;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.OrderColumn;
+import jakarta.persistence.Table;
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.List;
+import lombok.Getter;
+import lombok.Setter;
+import nl.agilecc.agiledancers.model.specifications.DayPartType;
+
+@Getter
+@Setter
+@Entity(name = "StoredDayPart")
+@Table(name = "day_part")
+public class DayPartEntity {
+    @EmbeddedId
+    private DayPartId id;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumns({
+        @JoinColumn(name = "school_id", referencedColumnName = "school_id", insertable = false, updatable = false),
+        @JoinColumn(name = "show_id", referencedColumnName = "id", insertable = false, updatable = false)
+    })
+    private ShowEntity show;
+
+    @Column(name = "day", nullable = false)
+    private LocalDate date;
+
+    @Enumerated(EnumType.STRING)
+    @Column(name = "part_type", nullable = false)
+    private DayPartType type;
+
+    @ElementCollection
+    @CollectionTable(
+            name = "assignment",
+            joinColumns = {
+                @JoinColumn(name = "school_id", referencedColumnName = "school_id"),
+                @JoinColumn(name = "show_id", referencedColumnName = "show_id"),
+                @JoinColumn(name = "part_position", referencedColumnName = "position")
+            })
+    @OrderColumn(name = "position")
+    @Column(name = "group_id", nullable = false)
+    private List<Long> groupIds = new ArrayList<>();
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/DayPartId.java

@@ -0,0 +1,26 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.Embeddable;
+import java.io.Serializable;
+import lombok.AllArgsConstructor;
+import lombok.EqualsAndHashCode;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+@Getter
+@Setter
+@Embeddable
+@AllArgsConstructor
+@NoArgsConstructor
+@EqualsAndHashCode
+public class DayPartId implements Serializable {
+    @jakarta.persistence.Column(name = "school_id")
+    private long schoolId;
+
+    @jakarta.persistence.Column(name = "show_id")
+    private long showId;
+
+    @jakarta.persistence.Column(name = "position")
+    private int position;
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/EntityIdentifiers.java

@@ -0,0 +1,24 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+@Entity(name = "EntityIdentifiers")
+@Table(name = "entity_identifiers")
+public class EntityIdentifiers {
+    @Id
+    private int id;
+
+    @Column(name = "next_value", nullable = false)
+    private long nextValue;
+
+    public long claim() {
+        return nextValue++;
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/GroupEntity.java

@@ -0,0 +1,72 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.CollectionTable;
+import jakarta.persistence.Column;
+import jakarta.persistence.ElementCollection;
+import jakarta.persistence.Entity;
+import jakarta.persistence.EnumType;
+import jakarta.persistence.Enumerated;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+import java.util.LinkedHashSet;
+import java.util.Set;
+import lombok.Getter;
+import lombok.Setter;
+import nl.agilecc.agiledancers.model.specifications.DanceGroupStyle;
+import nl.agilecc.agiledancers.model.specifications.DanceGroupType;
+
+@Getter
+@Setter
+@Entity(name = "StoredGroup")
+@Table(name = "dance_group")
+public class GroupEntity extends SchoolMemberEntity {
+    @Column(nullable = false)
+    private String category;
+
+    @Enumerated(EnumType.STRING)
+    @Column(name = "group_type", nullable = false)
+    private DanceGroupType type;
+
+    @Column(name = "start_age", nullable = false)
+    private int startAge;
+
+    @Column(name = "end_age", nullable = false)
+    private int endAge;
+
+    // The shared school key is read from the owning row; only the linked member ID is writable.
+    @ManyToOne(
+            fetch = FetchType.LAZY,
+            cascade = {CascadeType.MERGE, CascadeType.PERSIST})
+    @org.hibernate.annotations.JoinColumnsOrFormulas({
+        @org.hibernate.annotations.JoinColumnOrFormula(
+                column = @JoinColumn(name = "coach_id", referencedColumnName = "id")),
+        @org.hibernate.annotations.JoinColumnOrFormula(
+                formula =
+                        @org.hibernate.annotations.JoinFormula(value = "school_id", referencedColumnName = "school_id"))
+    })
+    private CoachEntity coach;
+
+    @ElementCollection
+    @CollectionTable(
+            name = "group_style",
+            joinColumns = {
+                @JoinColumn(name = "school_id", referencedColumnName = "school_id"),
+                @JoinColumn(name = "group_id", referencedColumnName = "id")
+            })
+    @Enumerated(EnumType.STRING)
+    @Column(name = "style", nullable = false)
+    private Set<DanceGroupStyle> styles = new LinkedHashSet<>();
+
+    @ElementCollection
+    @CollectionTable(
+            name = "group_dancer",
+            joinColumns = {
+                @JoinColumn(name = "school_id", referencedColumnName = "school_id"),
+                @JoinColumn(name = "group_id", referencedColumnName = "id")
+            })
+    @Column(name = "dancer_id", nullable = false)
+    private Set<Long> dancerIds = new LinkedHashSet<>();
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/RunEntity.java

@@ -0,0 +1,59 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.AttributeOverride;
+import jakarta.persistence.Column;
+import jakarta.persistence.EmbeddedId;
+import jakarta.persistence.Entity;
+import jakarta.persistence.EnumType;
+import jakarta.persistence.Enumerated;
+import jakarta.persistence.Table;
+import java.time.Instant;
+import java.util.UUID;
+import lombok.Getter;
+import lombok.Setter;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingPhase;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingState;
+
+@Getter
+@Setter
+@Entity(name = "StoredRun")
+@Table(name = "scheduling_run")
+public class RunEntity {
+    @EmbeddedId
+    @AttributeOverride(name = "localId", column = @Column(name = "show_id"))
+    private SchoolMemberId id;
+
+    @Column(name = "run_id", nullable = false)
+    private UUID runId;
+
+    @Column(name = "show_name", nullable = false)
+    private String showName;
+
+    @Column(name = "started_at", nullable = false)
+    private Instant startedAt;
+
+    @Column(name = "finished_at")
+    private Instant finishedAt;
+
+    @Enumerated(EnumType.STRING)
+    @Column(nullable = false)
+    private SchedulingState state;
+
+    @Enumerated(EnumType.STRING)
+    @Column(nullable = false)
+    private SchedulingPhase phase;
+
+    private boolean feasible;
+
+    @Column(nullable = false)
+    private String message;
+
+    @Column(name = "attendance_excess")
+    private Long attendanceExcess;
+
+    @Column(name = "performance_spread")
+    private Integer performanceSpread;
+
+    @Column(name = "variety_penalty")
+    private Long varietyPenalty;
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/SchoolEntity.java

@@ -0,0 +1,52 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.OneToMany;
+import jakarta.persistence.OrderBy;
+import jakarta.persistence.Table;
+import jakarta.persistence.Version;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+@Entity(name = "StoredSchool")
+@Table(name = "school")
+public class SchoolEntity {
+    @Id
+    private long id;
+
+    @Column(name = "school_key", nullable = false)
+    private UUID key;
+
+    @Column(nullable = false)
+    private String name;
+
+    @Version
+    private long revision;
+    // Marks child-only changes so Hibernate advances the aggregate version exactly once.
+    @Column(name = "change_stamp", nullable = false)
+    private long changeStamp;
+
+    @OneToMany(mappedBy = "school", cascade = CascadeType.ALL, orphanRemoval = true)
+    @OrderBy("id.localId")
+    private List<DancerEntity> dancers = new ArrayList<>();
+
+    @OneToMany(mappedBy = "school", cascade = CascadeType.ALL, orphanRemoval = true)
+    @OrderBy("id.localId")
+    private List<CoachEntity> coaches = new ArrayList<>();
+
+    @OneToMany(mappedBy = "school", cascade = CascadeType.ALL, orphanRemoval = true)
+    @OrderBy("id.localId")
+    private List<GroupEntity> groups = new ArrayList<>();
+
+    @OneToMany(mappedBy = "school", cascade = CascadeType.ALL, orphanRemoval = true)
+    @OrderBy("id.localId")
+    private List<ShowEntity> shows = new ArrayList<>();
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/SchoolMemberEntity.java

@@ -0,0 +1,21 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.EmbeddedId;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.MappedSuperclass;
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+@MappedSuperclass
+public abstract class SchoolMemberEntity {
+    @EmbeddedId
+    private SchoolMemberId id;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "school_id", insertable = false, updatable = false)
+    private SchoolEntity school;
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/SchoolMemberId.java

@@ -0,0 +1,23 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.Embeddable;
+import java.io.Serializable;
+import lombok.AllArgsConstructor;
+import lombok.EqualsAndHashCode;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+@Getter
+@Setter
+@Embeddable
+@AllArgsConstructor
+@NoArgsConstructor
+@EqualsAndHashCode
+public class SchoolMemberId implements Serializable {
+    @jakarta.persistence.Column(name = "school_id")
+    private long schoolId;
+
+    @jakarta.persistence.Column(name = "id")
+    private long localId;
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/repository/entity/ShowEntity.java

@@ -0,0 +1,51 @@
+package nl.agilecc.agiledancers.repository.entity;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.CollectionTable;
+import jakarta.persistence.Column;
+import jakarta.persistence.ElementCollection;
+import jakarta.persistence.Entity;
+import jakarta.persistence.EnumType;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.MapKeyColumn;
+import jakarta.persistence.MapKeyEnumerated;
+import jakarta.persistence.OneToMany;
+import jakarta.persistence.OrderBy;
+import jakarta.persistence.Table;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import lombok.Getter;
+import lombok.Setter;
+import nl.agilecc.agiledancers.model.specifications.DanceGroupType;
+
+@Getter
+@Setter
+@Entity(name = "StoredShow")
+@Table(name = "show")
+public class ShowEntity extends SchoolMemberEntity {
+    @Column(nullable = false)
+    private String name;
+
+    @Column(name = "preferred_day_parts", nullable = false)
+    private int preferredDayParts;
+
+    private boolean finalized;
+
+    @ElementCollection
+    @CollectionTable(
+            name = "show_appearance",
+            joinColumns = {
+                @JoinColumn(name = "school_id", referencedColumnName = "school_id"),
+                @JoinColumn(name = "show_id", referencedColumnName = "id")
+            })
+    @MapKeyEnumerated(EnumType.STRING)
+    @MapKeyColumn(name = "group_type")
+    @Column(name = "appearances", nullable = false)
+    private Map<DanceGroupType, Integer> appearances = new LinkedHashMap<>();
+
+    @OneToMany(mappedBy = "show", cascade = CascadeType.ALL, orphanRemoval = true)
+    @OrderBy("id.position")
+    private List<DayPartEntity> dayParts = new ArrayList<>();
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/CoachResource.java

@@ -15,29 +15,33 @@ import jakarta.ws.rs.core.MediaType;
 import java.util.List;
 import nl.agilecc.agiledancers.rest.apimodel.CoachRequest;
 import nl.agilecc.agiledancers.rest.apimodel.CoachView;
+import nl.agilecc.agiledancers.rest.mapping.DomainViewMapper;
 import nl.agilecc.agiledancers.service.CoachLinks;
 
+@SchoolTransactionBoundary
 @Path("/api/dance-schools/{schoolId}/coaches")
 @Produces(MediaType.APPLICATION_JSON)
 @Consumes(MediaType.APPLICATION_JSON)
 public class CoachResource {
+    private @Inject DomainViewMapper views;
+
     private @Inject CoachLinks links;
     private @PathParam("schoolId") long schoolId;
 
     @GET
     public List<CoachView> list() {
-        return links.list(schoolId).stream().map(CoachView::of).toList();
+        return links.list(schoolId).stream().map(views::coach).toList();
     }
 
     @POST
     public CoachView create(final @NotNull @Valid CoachRequest request) {
-        return CoachView.of(links.link(schoolId, null, request.dancerId()));
+        return views.coach(links.link(schoolId, null, request.dancerId()));
     }
 
     @PUT
     @Path("/{id}")
     public CoachView link(final @PathParam("id") long id, final @NotNull @Valid CoachRequest request) {
-        return CoachView.of(links.link(schoolId, id, request.dancerId()));
+        return views.coach(links.link(schoolId, id, request.dancerId()));
     }
 
     @DELETE

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/DanceGroupResource.java

@@ -19,26 +19,30 @@ import java.util.List;
 import nl.agilecc.agiledancers.model.DanceGroup;
 import nl.agilecc.agiledancers.rest.apimodel.GroupRequest;
 import nl.agilecc.agiledancers.rest.apimodel.GroupView;
+import nl.agilecc.agiledancers.rest.mapping.DomainViewMapper;
 import nl.agilecc.agiledancers.service.SchoolManagementService;
 import nl.agilecc.agiledancers.service.model.GroupDetails;
 
+@SchoolTransactionBoundary
 @Path("/api/dance-schools/{schoolId}/dance-groups")
 @Produces(MediaType.APPLICATION_JSON)
 @Consumes(MediaType.APPLICATION_JSON)
 public class DanceGroupResource {
+    private @Inject DomainViewMapper views;
+
     private @Inject SchoolManagementService service;
 
     private @PathParam("schoolId") long schoolId;
 
     @GET
     public List<GroupView> list() {
-        return service.groups(schoolId).stream().map(GroupView::of).toList();
+        return service.groups(schoolId).stream().map(views::group).toList();
     }
 
     @GET
     @Path("/{id}")
     public GroupView get(final @PathParam("id") long id) {
-        return GroupView.of(service.group(schoolId, id));
+        return views.group(service.group(schoolId, id));
     }
 
     @POST
@@ -50,14 +54,14 @@ public class DanceGroupResource {
         return Response.created(uriInfo.getAbsolutePathBuilder()
                         .path(entity.getId().toString())
                         .build())
-                .entity(GroupView.of(entity))
+                .entity(views.group(entity))
                 .build();
     }
 
     @PUT
     @Path("/{id}")
     public GroupView update(final @PathParam("id") long id, final @NotNull @Valid GroupRequest request) {
-        return GroupView.of(service.updateGroup(
+        return views.group(service.updateGroup(
                 schoolId,
                 id,
                 new GroupDetails(

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/DanceSchoolResource.java

@@ -19,23 +19,44 @@ import java.util.List;
 import nl.agilecc.agiledancers.model.DanceSchool;
 import nl.agilecc.agiledancers.rest.apimodel.SchoolRequest;
 import nl.agilecc.agiledancers.rest.apimodel.SchoolView;
+import nl.agilecc.agiledancers.rest.mapping.DomainViewMapper;
 import nl.agilecc.agiledancers.service.SchoolManagementService;
 
+@SchoolTransactionBoundary
 @Path("/api/dance-schools")
 @Produces(MediaType.APPLICATION_JSON)
 @Consumes(MediaType.APPLICATION_JSON)
 public class DanceSchoolResource {
+    private @Inject DomainViewMapper views;
+
     private @Inject SchoolManagementService service;
 
+    private @Inject nl.agilecc.agiledancers.service.ShowSchedules schedules;
+
+    @GET
+    @Path("/{id}/data")
+    public nl.agilecc.agiledancers.rest.apimodel.SchoolDataView data(final @PathParam("id") long id) {
+        final DanceSchool school = service.school(id);
+        return new nl.agilecc.agiledancers.rest.apimodel.SchoolDataView(
+                views.school(school),
+                school.getDancers().stream().map(views::dancer).toList(),
+                school.getDanceGroups().stream().map(views::group).toList(),
+                school.getShows().stream()
+                        .map((final nl.agilecc.agiledancers.model.Show show) ->
+                                views.show(show, schedules.violations(id, show.getId())))
+                        .toList(),
+                school.getCoaches().stream().map(views::coach).toList());
+    }
+
     @GET
     public List<SchoolView> list() {
-        return service.schools().stream().map(SchoolView::of).toList();
+        return service.schools().stream().map(views::school).toList();
     }
 
     @GET
     @Path("/{id}")
     public SchoolView get(final @PathParam("id") long id) {
-        return SchoolView.of(service.school(id));
+        return views.school(service.school(id));
     }
 
     @POST
@@ -44,14 +65,14 @@ public class DanceSchoolResource {
         return Response.created(uriInfo.getAbsolutePathBuilder()
                         .path(entity.getId().toString())
                         .build())
-                .entity(SchoolView.of(entity))
+                .entity(views.school(entity))
                 .build();
     }
 
     @PUT
     @Path("/{id}")
     public SchoolView update(final @PathParam("id") long id, final @NotNull @Valid SchoolRequest request) {
-        return SchoolView.of(service.updateSchool(id, request.name()));
+        return views.school(service.updateSchool(id, request.name()));
     }
 
     @DELETE

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/DancerResource.java

@@ -19,25 +19,29 @@ import java.util.List;
 import nl.agilecc.agiledancers.model.Dancer;
 import nl.agilecc.agiledancers.rest.apimodel.DancerRequest;
 import nl.agilecc.agiledancers.rest.apimodel.DancerView;
+import nl.agilecc.agiledancers.rest.mapping.DomainViewMapper;
 import nl.agilecc.agiledancers.service.SchoolManagementService;
 
+@SchoolTransactionBoundary
 @Path("/api/dance-schools/{schoolId}/dancers")
 @Produces(MediaType.APPLICATION_JSON)
 @Consumes(MediaType.APPLICATION_JSON)
 public class DancerResource {
+    private @Inject DomainViewMapper views;
+
     private @Inject SchoolManagementService service;
 
     private @PathParam("schoolId") long schoolId;
 
     @GET
     public List<DancerView> list() {
-        return service.dancers(schoolId).stream().map(DancerView::of).toList();
+        return service.dancers(schoolId).stream().map(views::dancer).toList();
     }
 
     @GET
     @Path("/{id}")
     public DancerView get(final @PathParam("id") long id) {
-        return DancerView.of(service.dancer(schoolId, id));
+        return views.dancer(service.dancer(schoolId, id));
     }
 
     @POST
@@ -46,14 +50,14 @@ public class DancerResource {
         return Response.created(uriInfo.getAbsolutePathBuilder()
                         .path(entity.getId().toString())
                         .build())
-                .entity(DancerView.of(entity))
+                .entity(views.dancer(entity))
                 .build();
     }
 
     @PUT
     @Path("/{id}")
     public DancerView update(final @PathParam("id") long id, final @NotNull @Valid DancerRequest request) {
-        return DancerView.of(service.updateDancer(schoolId, id, request.name(), request.birthDate()));
+        return views.dancer(service.updateDancer(schoolId, id, request.name(), request.birthDate()));
     }
 
     @DELETE

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/ManagementExceptionMapper.java

@@ -13,6 +13,7 @@ public class ManagementExceptionMapper implements ExceptionMapper<ManagementExce
     public Response toResponse(final ManagementException exception) {
         final int status = switch (exception.getKind()) {
             case NOT_FOUND -> 404;
+            case STORAGE_UNAVAILABLE -> 503;
             case INVALID_INPUT -> 400;
             case CONFLICT -> 409;
         };

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/SchedulingEventsResource.java

@@ -0,0 +1,44 @@
+package nl.agilecc.agiledancers.rest;
+
+import io.smallrye.mutiny.Multi;
+import io.smallrye.mutiny.subscription.BackPressureStrategy;
+import jakarta.inject.Inject;
+import jakarta.ws.rs.GET;
+import jakarta.ws.rs.Path;
+import jakarta.ws.rs.Produces;
+import jakarta.ws.rs.core.MediaType;
+import java.time.Duration;
+import java.util.List;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingRun;
+import nl.agilecc.agiledancers.rest.apimodel.SchedulingEventView;
+import nl.agilecc.agiledancers.service.SchedulingRuns;
+import org.jboss.resteasy.reactive.RestStreamElementType;
+
+@Path("/api/scheduling/events")
+public class SchedulingEventsResource {
+    private @Inject SchedulingRuns scheduling;
+
+    @GET
+    @Produces(MediaType.SERVER_SENT_EVENTS)
+    @RestStreamElementType(MediaType.APPLICATION_JSON)
+    public Multi<SchedulingEventView> events() {
+        final Multi<SchedulingEventView> updates = Multi.createFrom()
+                .emitter(
+                        (final io.smallrye.mutiny.subscription.MultiEmitter<? super SchedulingEventView> emitter) -> {
+                            final Runnable unsubscribe = scheduling.subscribe(
+                                    (final List<SchedulingRun> runs) -> emitter.emit(new SchedulingEventView(runs)));
+                            emitter.onTermination(unsubscribe);
+                        },
+                        BackPressureStrategy.LATEST);
+        // Heartbeats keep idle proxy connections alive without changing the current snapshot.
+        final Multi<SchedulingEventView> heartbeat = Multi.createFrom()
+                .ticks()
+                .every(Duration.ofSeconds(15))
+                .onItem()
+                .transform((final Long tick) -> new SchedulingEventView(null));
+        return Multi.createBy()
+                .merging()
+                .streams(updates, heartbeat)
+                .runSubscriptionOn(io.smallrye.mutiny.infrastructure.Infrastructure.getDefaultWorkerPool());
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/SchoolRequestInterceptor.java

@@ -0,0 +1,50 @@
+package nl.agilecc.agiledancers.rest;
+
+import io.vertx.ext.web.RoutingContext;
+import jakarta.annotation.Priority;
+import jakarta.inject.Inject;
+import jakarta.interceptor.AroundInvoke;
+import jakarta.interceptor.Interceptor;
+import jakarta.interceptor.InvocationContext;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import nl.agilecc.agiledancers.service.ManagementException;
+import nl.agilecc.agiledancers.service.ManagementExceptionKind;
+import nl.agilecc.agiledancers.service.SchoolTransactions;
+import nl.agilecc.agiledancers.service.model.SchoolChange;
+
+@SchoolTransactionBoundary
+@Interceptor
+@Priority(Interceptor.Priority.APPLICATION)
+public class SchoolRequestInterceptor {
+    private static final Pattern SCHOOL_PATH = Pattern.compile("/api/dance-schools/(\\d+)(?:/|$)");
+    private @Inject RoutingContext context;
+    private @Inject SchoolTransactions transactions;
+
+    @AroundInvoke
+    public Object invoke(final InvocationContext invocation) throws Exception {
+        final String path = context.request().path();
+        final String method = context.request().method().name();
+        final boolean mutation = !method.equals("GET") && !path.endsWith("/preview");
+        final Matcher matcher = SCHOOL_PATH.matcher(path);
+        final Long schoolId = matcher.find()
+                ? Long.valueOf(matcher.group(1))
+                : number(context.request().getParam("replaceId"));
+        final Long revision = mutation ? number(context.request().getHeader("X-School-Revision")) : null;
+        return transactions.request(
+                new SchoolChange(schoolId, revision, mutation, mutation && !path.endsWith("/schedule")),
+                invocation::proceed);
+    }
+
+    private static Long number(final String value) {
+        if (value == null) {
+            return null;
+        }
+        try {
+            return Long.valueOf(value);
+        } catch (final NumberFormatException failure) {
+            throw new ManagementException(
+                    ManagementExceptionKind.INVALID_INPUT, "Ongeldige schoolversie of school-ID.");
+        }
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/SchoolSnapshotResource.java

@@ -15,15 +15,19 @@ import jakarta.ws.rs.QueryParam;
 import jakarta.ws.rs.core.MediaType;
 import jakarta.ws.rs.core.Response;
 import nl.agilecc.agiledancers.rest.apimodel.SchoolView;
+import nl.agilecc.agiledancers.rest.mapping.DomainViewMapper;
 import nl.agilecc.agiledancers.service.ManagementException;
 import nl.agilecc.agiledancers.service.ManagementExceptionKind;
 import nl.agilecc.agiledancers.service.SchoolManagementService;
 import nl.agilecc.agiledancers.service.model.ImportPreview;
 import nl.agilecc.agiledancers.service.model.SchoolSnapshot;
 
+@SchoolTransactionBoundary
 @Path("/api/dance-schools")
 @Produces(MediaType.APPLICATION_JSON)
 public class SchoolSnapshotResource {
+    private @Inject DomainViewMapper views;
+
     private @Inject SchoolManagementService service;
 
     private @Inject ObjectMapper mapper;
@@ -48,7 +52,7 @@ public class SchoolSnapshotResource {
     @Path("/import")
     @Consumes(MediaType.APPLICATION_JSON)
     public SchoolView apply(final String json, final @QueryParam("replaceId") Long replaceId) {
-        return SchoolView.of(service.importSchool(parse(json), replaceId));
+        return views.school(service.importSchool(parse(json), replaceId));
     }
 
     private SchoolSnapshot parse(final String json) {

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/SchoolTransactionBoundary.java

@@ -0,0 +1,13 @@
+package nl.agilecc.agiledancers.rest;
+
+import jakarta.interceptor.InterceptorBinding;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/** Bounds school HTTP operations to one durable transaction and optimistic revision check. */
+@InterceptorBinding
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.TYPE, ElementType.METHOD})
+public @interface SchoolTransactionBoundary {}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/ShowResource.java

@@ -18,23 +18,26 @@ import jakarta.ws.rs.core.UriInfo;
 import java.util.List;
 import nl.agilecc.agiledancers.model.DayPart;
 import nl.agilecc.agiledancers.model.Show;
-import nl.agilecc.agiledancers.model.scheduling.SchedulingResult;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingRun;
 import nl.agilecc.agiledancers.rest.apimodel.DayPartRequest;
 import nl.agilecc.agiledancers.rest.apimodel.ScheduleRequest;
-import nl.agilecc.agiledancers.rest.apimodel.SchedulingView;
 import nl.agilecc.agiledancers.rest.apimodel.ShowRequest;
 import nl.agilecc.agiledancers.rest.apimodel.ShowView;
-import nl.agilecc.agiledancers.service.SchedulingService;
+import nl.agilecc.agiledancers.rest.mapping.DomainViewMapper;
+import nl.agilecc.agiledancers.service.SchedulingRuns;
 import nl.agilecc.agiledancers.service.SchoolManagementService;
 import nl.agilecc.agiledancers.service.ShowSchedules;
 
+@SchoolTransactionBoundary
 @Path("/api/dance-schools/{schoolId}/shows")
 @Produces(MediaType.APPLICATION_JSON)
 @Consumes(MediaType.APPLICATION_JSON)
 public class ShowResource {
+    private @Inject DomainViewMapper views;
+
     private @Inject SchoolManagementService service;
 
-    private @Inject SchedulingService scheduling;
+    private @Inject SchedulingRuns scheduling;
 
     private @Inject ShowSchedules schedules;
 
@@ -68,7 +71,7 @@ public class ShowResource {
     }
 
     private ShowView view(final Show show) {
-        return ShowView.of(show, schedules.violations(schoolId, show.getId()));
+        return views.show(show, schedules.violations(schoolId, show.getId()));
     }
 
     private static Show settings(final ShowRequest request) {
@@ -105,10 +108,14 @@ public class ShowResource {
     @POST
     @Path("/{id}/schedule")
     @Consumes(MediaType.WILDCARD)
-    public SchedulingView schedule(final @PathParam("id") long id) {
-        final SchedulingResult result = scheduling.schedule(schoolId, id);
-        return new SchedulingView(
-                result.optimal(), result.optimal() ? "Optimal schedule" : "Valid schedule; optimality not proven");
+    public Response schedule(final @PathParam("id") long id) {
+        return Response.accepted(scheduling.start(schoolId, id)).build();
+    }
+
+    @GET
+    @Path("/{id}/schedule")
+    public SchedulingRun schedulingStatus(final @PathParam("id") long id) {
+        return scheduling.status(schoolId, id);
     }
 
     @DELETE

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/apimodel/CoachView.java

@@ -1,12 +1,3 @@
 package nl.agilecc.agiledancers.rest.apimodel;
 
-import nl.agilecc.agiledancers.model.Coach;
-
-public record CoachView(long id, String name, Long dancerId) {
-    public static CoachView of(final Coach coach) {
-        return new CoachView(
-                coach.getId(),
-                coach.getName(),
-                coach.getDancer() == null ? null : coach.getDancer().getId());
-    }
-}
+public record CoachView(long id, String name, Long dancerId) {}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/apimodel/DancerView.java

@@ -1,10 +1,5 @@
 package nl.agilecc.agiledancers.rest.apimodel;
 
 import java.time.LocalDate;
-import nl.agilecc.agiledancers.model.Dancer;
 
-public record DancerView(long id, String name, LocalDate birthDate) {
-    public static DancerView of(final Dancer dancer) {
-        return new DancerView(dancer.getId(), dancer.getName(), dancer.getBirthDate());
-    }
-}
+public record DancerView(long id, String name, LocalDate birthDate) {}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/apimodel/GroupView.java

@@ -5,8 +5,6 @@ import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
-import nl.agilecc.agiledancers.model.DanceGroup;
-import nl.agilecc.agiledancers.model.Dancer;
 import nl.agilecc.agiledancers.model.specifications.DanceGroupStyle;
 import nl.agilecc.agiledancers.model.specifications.DanceGroupType;
 
@@ -22,15 +20,4 @@ public record GroupView(
         styles = styles == null ? null : Collections.unmodifiableSet(new LinkedHashSet<>(styles));
         dancerIds = dancerIds == null ? null : Collections.unmodifiableList(new ArrayList<>(dancerIds));
     }
-
-    public static GroupView of(final DanceGroup group) {
-        return new GroupView(
-                group.getId(),
-                group.getCategory(),
-                group.getType(),
-                group.getStartAge(),
-                group.getEndAge(),
-                Set.copyOf(group.getStyles()),
-                group.getDancers().stream().map(Dancer::getId).toList());
-    }
 }

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/apimodel/SchedulingEventView.java

@@ -0,0 +1,11 @@
+package nl.agilecc.agiledancers.rest.apimodel;
+
+import java.util.List;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingRun;
+
+/** A null runs field is a heartbeat, not a replacement of the current snapshot. */
+public record SchedulingEventView(List<SchedulingRun> runs) {
+    public SchedulingEventView {
+        runs = runs == null ? null : List.copyOf(runs);
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/apimodel/SchoolDataView.java

@@ -0,0 +1,18 @@
+package nl.agilecc.agiledancers.rest.apimodel;
+
+import java.util.List;
+
+/** One school and all editor data from the same revision and database snapshot. */
+public record SchoolDataView(
+        SchoolView school,
+        List<DancerView> dancers,
+        List<GroupView> groups,
+        List<ShowView> shows,
+        List<CoachView> coaches) {
+    public SchoolDataView {
+        dancers = List.copyOf(dancers);
+        groups = List.copyOf(groups);
+        shows = List.copyOf(shows);
+        coaches = List.copyOf(coaches);
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/apimodel/SchoolView.java

@@ -3,24 +3,12 @@ package nl.agilecc.agiledancers.rest.apimodel;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import nl.agilecc.agiledancers.model.DanceGroup;
-import nl.agilecc.agiledancers.model.DanceSchool;
-import nl.agilecc.agiledancers.model.Dancer;
-import nl.agilecc.agiledancers.model.Show;
 
-public record SchoolView(long id, String name, List<Long> dancerIds, List<Long> danceGroupIds, List<Long> showIds) {
+public record SchoolView(
+        long id, long revision, String name, List<Long> dancerIds, List<Long> danceGroupIds, List<Long> showIds) {
     public SchoolView {
         dancerIds = dancerIds == null ? null : Collections.unmodifiableList(new ArrayList<>(dancerIds));
         danceGroupIds = danceGroupIds == null ? null : Collections.unmodifiableList(new ArrayList<>(danceGroupIds));
         showIds = showIds == null ? null : Collections.unmodifiableList(new ArrayList<>(showIds));
     }
-
-    public static SchoolView of(final DanceSchool school) {
-        return new SchoolView(
-                school.getId(),
-                school.getName(),
-                school.getDancers().stream().map(Dancer::getId).toList(),
-                school.getDanceGroups().stream().map(DanceGroup::getId).toList(),
-                school.getShows().stream().map(Show::getId).toList());
-    }
 }

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/apimodel/ShowView.java

@@ -5,9 +5,6 @@ import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
-import nl.agilecc.agiledancers.model.DanceGroup;
-import nl.agilecc.agiledancers.model.DayPart;
-import nl.agilecc.agiledancers.model.Show;
 import nl.agilecc.agiledancers.model.specifications.DanceGroupType;
 
 public record ShowView(
@@ -23,26 +20,4 @@ public record ShowView(
         dayParts = dayParts == null ? null : Collections.unmodifiableList(new ArrayList<>(dayParts));
         appearances = appearances == null ? null : Collections.unmodifiableMap(new LinkedHashMap<>(appearances));
     }
-
-    public static ShowView of(final Show show) {
-        return of(show, List.of());
-    }
-
-    public static ShowView of(final Show show, final List<String> violations) {
-        return new ShowView(
-                show.getId(),
-                show.getName(),
-                show.getDayParts().stream()
-                        .map((final DayPart p) -> new DayPartView(
-                                p.getDate(),
-                                p.getType(),
-                                p.getDanceGroups().stream()
-                                        .map(DanceGroup::getId)
-                                        .toList()))
-                        .toList(),
-                show.getAppearances(),
-                nl.agilecc.agiledancers.service.SchedulingInputs.preferred(show),
-                show.isFinalized(),
-                violations);
-    }
 }

agiledancers-be/src/main/java/nl/agilecc/agiledancers/rest/mapping/DomainViewMapper.java

@@ -0,0 +1,59 @@
+package nl.agilecc.agiledancers.rest.mapping;
+
+import java.util.List;
+import nl.agilecc.agiledancers.model.AbstractEntity;
+import nl.agilecc.agiledancers.model.Coach;
+import nl.agilecc.agiledancers.model.DanceGroup;
+import nl.agilecc.agiledancers.model.DanceSchool;
+import nl.agilecc.agiledancers.model.Dancer;
+import nl.agilecc.agiledancers.model.DayPart;
+import nl.agilecc.agiledancers.model.Show;
+import nl.agilecc.agiledancers.rest.apimodel.CoachView;
+import nl.agilecc.agiledancers.rest.apimodel.DancerView;
+import nl.agilecc.agiledancers.rest.apimodel.DayPartView;
+import nl.agilecc.agiledancers.rest.apimodel.GroupView;
+import nl.agilecc.agiledancers.rest.apimodel.SchoolView;
+import nl.agilecc.agiledancers.rest.apimodel.ShowView;
+import nl.agilecc.agiledancers.service.SchedulingInputs;
+import org.mapstruct.AnnotateWith;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.MappingConstants;
+import org.mapstruct.Named;
+import org.mapstruct.ReportingPolicy;
+
+/** Generates API projections only; domain graph identity and validation remain application-owned. */
+// Mark generated implementations so coverage and architecture checks retain their handwritten-code scope.
+@AnnotateWith(lombok.Generated.class)
+@Mapper(componentModel = MappingConstants.ComponentModel.JAKARTA_CDI, unmappedTargetPolicy = ReportingPolicy.ERROR)
+public interface DomainViewMapper {
+    @Mapping(target = "dancerIds", source = "dancers")
+    @Mapping(target = "danceGroupIds", source = "danceGroups")
+    @Mapping(target = "showIds", source = "shows")
+    public SchoolView school(final DanceSchool school);
+
+    public DancerView dancer(final Dancer dancer);
+
+    @Mapping(target = "dancerIds", source = "dancers")
+    public GroupView group(final DanceGroup group);
+
+    @Mapping(target = "dancerId", source = "dancer")
+    public CoachView coach(final Coach coach);
+
+    @Mapping(target = "danceGroupIds", source = "danceGroups")
+    public DayPartView dayPart(final DayPart part);
+
+    /** Violations are calculated by the use case, never inferred by the mapper. */
+    @Mapping(target = "violations", source = "violations")
+    @Mapping(target = "preferredDayParts", source = "show", qualifiedByName = "preferredDayParts")
+    public ShowView show(final Show show, final List<String> violations);
+
+    public default Long id(final AbstractEntity entity) {
+        return entity == null ? null : entity.getId();
+    }
+
+    @Named("preferredDayParts")
+    public default int preferredDayParts(final Show show) {
+        return SchedulingInputs.preferred(show);
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/service/ManagementExceptionKind.java

@@ -2,6 +2,7 @@ package nl.agilecc.agiledancers.service;
 
 public enum ManagementExceptionKind {
     NOT_FOUND,
+    STORAGE_UNAVAILABLE,
     INVALID_INPUT,
     CONFLICT
 }

agiledancers-be/src/main/java/nl/agilecc/agiledancers/service/SchedulingFailure.java

@@ -0,0 +1,17 @@
+package nl.agilecc.agiledancers.service;
+
+import nl.agilecc.agiledancers.model.scheduling.SchedulingFailureKind;
+
+/** Carries a stable calculation outcome independently of its human-readable explanation. */
+public class SchedulingFailure extends ManagementException {
+    private final SchedulingFailureKind outcome;
+
+    public SchedulingFailure(final SchedulingFailureKind outcome, final String message) {
+        super(ManagementExceptionKind.INVALID_INPUT, message);
+        this.outcome = outcome;
+    }
+
+    public SchedulingFailureKind getOutcome() {
+        return outcome;
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/service/SchedulingPersistence.java

@@ -0,0 +1,54 @@
+package nl.agilecc.agiledancers.service;
+
+import jakarta.inject.Inject;
+import jakarta.inject.Singleton;
+import java.util.List;
+import java.util.concurrent.Callable;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingRun;
+import nl.agilecc.agiledancers.repository.Database;
+import nl.agilecc.agiledancers.repository.RunRepository;
+
+/** Coordinates scheduling status with the same unit of work as domain changes. */
+@Singleton
+public class SchedulingPersistence {
+    private final SchoolTransactions transactions;
+    private final Database database;
+    private final RunRepository runs;
+
+    @Inject
+    public SchedulingPersistence(
+            final SchoolTransactions transactions, final Database database, final RunRepository runs) {
+        this.transactions = transactions;
+        this.database = database;
+        this.runs = runs;
+    }
+
+    public List<SchedulingRun> recover() {
+        return transactions.background(() -> {
+            runs.recover();
+            return runs.load();
+        });
+    }
+
+    public List<SchedulingRun> load() {
+        return transactions.background(runs::load);
+    }
+
+    public <T> T work(final Callable<T> action) {
+        return transactions.background(action);
+    }
+
+    public void save(final SchedulingRun run, final Runnable publication) {
+        runs.save(run);
+        database.afterCommit(publication);
+    }
+
+    public void accepted(final SchedulingRun run, final Runnable launch, final Runnable rollback) {
+        database.afterRollback(rollback);
+        save(run, launch);
+    }
+
+    public void result(final long schoolId) {
+        transactions.saveResult(schoolId);
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/service/SchedulingRuns.java

@@ -0,0 +1,240 @@
+package nl.agilecc.agiledancers.service;
+
+import io.quarkus.runtime.Startup;
+import jakarta.annotation.PostConstruct;
+import jakarta.annotation.PreDestroy;
+import jakarta.inject.Inject;
+import jakarta.inject.Singleton;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.function.Consumer;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingInput;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingProgress;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingResult;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingRun;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingState;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingSummary;
+import nl.agilecc.agiledancers.repository.StorageException;
+import nl.agilecc.agiledancers.service.port.SchedulingEngine;
+
+/** Owns background tasks; the school monitor orders short commits and publication, never solver computation. */
+@Startup
+@Singleton
+public class SchedulingRuns {
+    private final SchoolManagementService schools;
+    private final SchedulingEngine engine;
+    private final ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor();
+    private final Map<Long, SchedulingRun> runs = new HashMap<>();
+    private final Map<Object, Consumer<List<SchedulingRun>>> listeners = new HashMap<>();
+    private @Inject SchedulingPersistence persistence;
+
+    @Inject
+    public SchedulingRuns(final SchoolManagementService schools, final SchedulingEngine engine) {
+        this.schools = schools;
+        this.engine = engine;
+    }
+
+    @PostConstruct
+    public void recover() {
+        persistence.recover().forEach((final SchedulingRun run) -> runs.put(run.showId(), run));
+    }
+
+    public SchedulingRun start(final long schoolId, final long showId) {
+        synchronized (schools) {
+            final SchedulingInput input = schools.beginScheduling(schoolId, showId);
+            final SchedulingRun run = SchedulingRun.started(
+                    schoolId, showId, schools.show(schoolId, showId).getName());
+            final Runnable launch = () -> launch(run, input);
+            if (persistence == null) {
+                launch.run();
+            } else {
+                persistence.accepted(run, launch, () -> schools.endScheduling(showId));
+            }
+            return run;
+        }
+    }
+
+    private void launch(final SchedulingRun run, final SchedulingInput input) {
+        publish(run);
+        try {
+            executor.submit(() -> calculate(run, input));
+        } catch (final RuntimeException failure) {
+            finish(run.completed(
+                    SchedulingState.SOLVER_FAILED, "Berekening kon niet starten. Bestaande indeling behouden.", null));
+            if (persistence == null) {
+                throw failure;
+            }
+        }
+    }
+
+    public SchedulingRun status(final long schoolId, final long showId) {
+        synchronized (schools) {
+            schools.show(schoolId, showId);
+            return runs.get(showId);
+        }
+    }
+
+    /** Registration and initial snapshot share the publication lock, preventing a missed update. */
+    public Runnable subscribe(final Consumer<List<SchedulingRun>> listener) {
+        synchronized (schools) {
+            if (persistence != null) {
+                runs.clear();
+                persistence.load().forEach((final SchedulingRun run) -> runs.put(run.showId(), run));
+            }
+            final Object key = new Object();
+            listeners.put(key, listener);
+            listener.accept(List.copyOf(runs.values()));
+            return () -> unsubscribe(key);
+        }
+    }
+
+    private void unsubscribe(final Object key) {
+        synchronized (schools) {
+            listeners.remove(key);
+        }
+    }
+
+    private void publish(final SchedulingRun run) {
+        synchronized (schools) {
+            runs.put(run.showId(), run);
+            final List<SchedulingRun> snapshot = List.copyOf(runs.values());
+            for (final Consumer<List<SchedulingRun>> listener : List.copyOf(listeners.values())) {
+                notifyListener(listener, snapshot);
+            }
+        }
+    }
+
+    private void notifyListener(final Consumer<List<SchedulingRun>> listener, final List<SchedulingRun> snapshot) {
+        try {
+            listener.accept(snapshot);
+        } catch (final RuntimeException disconnected) {
+            // A disconnected transport must not turn a committed solver outcome into a failure.
+            listeners.values().remove(listener);
+        }
+    }
+
+    private void progress(final SchedulingRun run, final SchedulingProgress update) {
+        work(() -> {
+            save(latest(run).progressed(update));
+            return null;
+        });
+    }
+
+    private void calculate(final SchedulingRun run, final SchedulingInput input) {
+        try {
+            final SchedulingResult result =
+                    engine.solve(input, (final SchedulingProgress update) -> progress(run, update));
+            final SchedulingSummary summary = SchedulingSummary.of(input, result);
+            work(() -> {
+                schools.finishScheduling(run.schoolId(), input, result);
+                if (persistence != null) {
+                    persistence.result(run.schoolId());
+                }
+                save(latest(run)
+                        .completed(
+                                result.optimal() ? SchedulingState.OPTIMAL : SchedulingState.VALID,
+                                result.optimal()
+                                        ? "Optimaal conceptrooster."
+                                        : "Geldig conceptrooster; optimaliteit niet bewezen.",
+                                summary));
+                return null;
+            });
+            schools.endScheduling(run.showId());
+        } catch (final ManagementException failure) {
+            finish(failed(run, failure));
+        } catch (final RuntimeException | LinkageError failure) {
+            finish(latest(run)
+                    .completed(
+                            SchedulingState.SOLVER_FAILED, "Berekening mislukt. Bestaande indeling behouden.", null));
+        }
+    }
+
+    private SchedulingRun failed(final SchedulingRun run, final ManagementException failure) {
+        final SchedulingState outcome = failure instanceof final SchedulingFailure scheduling
+                ? switch (scheduling.getOutcome()) {
+                    case INFEASIBLE -> SchedulingState.INFEASIBLE;
+                    case NO_SOLUTION -> SchedulingState.NO_SOLUTION;
+                    case SOLVER_FAILED -> SchedulingState.SOLVER_FAILED;
+                }
+                : (failure.getKind() == ManagementExceptionKind.CONFLICT
+                        ? SchedulingState.STALE
+                        : SchedulingState.INVALID_INPUT);
+        return latest(run).completed(outcome, failure.getMessage() + " Bestaande indeling behouden.", null);
+    }
+
+    private SchedulingRun latest(final SchedulingRun run) {
+        synchronized (schools) {
+            return runs.get(run.showId());
+        }
+    }
+
+    private void finish(final SchedulingRun completed) {
+        try {
+            while (true) {
+                try {
+                    work(() -> {
+                        schools.show(completed.schoolId(), completed.showId());
+                        save(completed);
+                        return null;
+                    });
+                    return;
+                } catch (final StorageException unavailable) {
+                    // Keep the run guard and terminal outcome until storage recovers; never publish an uncommitted
+                    // status.
+                    if (executor.isShutdown() || !waitForStorage()) {
+                        return;
+                    }
+                } catch (final ManagementException removed) {
+                    if (removed.getKind() != ManagementExceptionKind.NOT_FOUND) {
+                        throw removed;
+                    }
+                    return;
+                }
+            }
+        } finally {
+            schools.endScheduling(completed.showId());
+        }
+    }
+
+    private boolean waitForStorage() {
+        try {
+            Thread.sleep(1000);
+            return true;
+        } catch (final InterruptedException stopping) {
+            Thread.currentThread().interrupt();
+            return false;
+        }
+    }
+
+    private void save(final SchedulingRun run) {
+        if (persistence == null) {
+            publish(run);
+        } else {
+            persistence.save(run, () -> publish(run));
+        }
+    }
+
+    private <T> T work(final Callable<T> action) {
+        synchronized (schools) {
+            if (persistence != null) {
+                return persistence.work(action);
+            }
+            try {
+                return action.call();
+            } catch (final RuntimeException failure) {
+                throw failure;
+            } catch (final Exception failure) {
+                throw new IllegalStateException(failure);
+            }
+        }
+    }
+
+    @PreDestroy
+    public void close() {
+        executor.shutdownNow();
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/service/SchoolManagementService.java

@@ -30,7 +30,7 @@ import nl.agilecc.agiledancers.service.model.GroupDetails;
 import nl.agilecc.agiledancers.service.model.ImportPreview;
 import nl.agilecc.agiledancers.service.model.SchoolSnapshot;
 
-/** Owns the in-memory school aggregates; all writes go through this shared service. */
+/** Owns detached school aggregates within the shared transaction monitor; all domain writes pass through here. */
 @Singleton
 public class SchoolManagementService {
     private final DanceSchoolRepository schools = new DanceSchoolRepository();
@@ -41,6 +41,27 @@ public class SchoolManagementService {
     private final Map<Long, Long> revisions = new HashMap<>();
     private final Set<Long> running = new HashSet<>();
 
+    /** Installs a detached relational snapshot under the service's existing aggregate lock. */
+    public synchronized void load(final List<DanceSchool> state, final java.util.function.LongSupplier identifiers) {
+        revisions.clear();
+        schools.load(state, identifiers);
+        dancers.load(
+                state.stream()
+                        .flatMap((final DanceSchool school) -> school.getDancers().stream())
+                        .toList(),
+                identifiers);
+        groups.load(
+                state.stream()
+                        .flatMap((final DanceSchool school) -> school.getDanceGroups().stream())
+                        .toList(),
+                identifiers);
+        shows.load(
+                state.stream()
+                        .flatMap((final DanceSchool school) -> school.getShows().stream())
+                        .toList(),
+                identifiers);
+    }
+
     public synchronized void touch(final Show show) {
         show.setFinalized(false);
         revisions.merge(show.getId(), 1L, Long::sum);
@@ -64,7 +85,8 @@ public class SchoolManagementService {
                     ManagementExceptionKind.INVALID_INPUT, "Correct preferredDayParts before scheduling.");
         }
         running.add(showId);
-        return SchedulingInputs.of(school(schoolId), show, revisions.getOrDefault(showId, 0L));
+        return SchedulingInputs.of(
+                school(schoolId), show, school(schoolId).getRevision() + revisions.getOrDefault(showId, 0L));
     }
 
     /** Validates the complete result and input revision before replacing any saved assignments. */
@@ -77,7 +99,7 @@ public class SchoolManagementService {
             throw new ManagementException(
                     ManagementExceptionKind.CONFLICT, "Scheduling inputs changed. Run scheduling again.");
         }
-        if (revisions.getOrDefault(input.showId(), 0L) != input.revision()) {
+        if (school(schoolId).getRevision() + revisions.getOrDefault(input.showId(), 0L) != input.revision()) {
             throw new ManagementException(
                     ManagementExceptionKind.CONFLICT, "Scheduling inputs changed. Run scheduling again.");
         }
@@ -320,12 +342,14 @@ public class SchoolManagementService {
                 snapshot.groups().size(),
                 snapshot.shows().size(),
                 existing == null ? null : existing.getId(),
-                existing == null ? null : existing.getName());
+                existing == null ? null : existing.getName(),
+                existing == null ? null : existing.getRevision());
     }
 
     /** Validates and stages the complete graph before replacing repositories; file IDs become runtime IDs. */
     public synchronized DanceSchool importSchool(final SchoolSnapshot snapshot, final Long replaceId) {
         final DanceSchool staged = snapshot.restore();
+        final long revision = replaceId == null ? 0 : school(replaceId).getRevision();
         final ImportPreview preview = preview(snapshot);
         if (!Objects.equals(preview.existingId(), replaceId)) {
             throw new ManagementException(
@@ -347,6 +371,7 @@ public class SchoolManagementService {
         final List<DanceGroup> rebuiltGroups = rebuildGroups(importedGroups, memberships, replacements);
         final List<Show> rebuiltShows = rebuildShows(importedShows, replacements);
         final DanceSchool imported = DanceSchool.builder()
+                .revision(revision)
                 .key(staged.getKey())
                 .name(staged.getName())
                 .dancers(new LinkedHashSet<>(importedDancers))

agiledancers-be/src/main/java/nl/agilecc/agiledancers/service/SchoolTransactions.java

@@ -0,0 +1,118 @@
+package nl.agilecc.agiledancers.service;
+
+import jakarta.inject.Inject;
+import jakarta.inject.Singleton;
+import java.util.List;
+import java.util.concurrent.Callable;
+import nl.agilecc.agiledancers.model.DanceSchool;
+import nl.agilecc.agiledancers.repository.Database;
+import nl.agilecc.agiledancers.repository.RevisionConflictException;
+import nl.agilecc.agiledancers.repository.SchoolReader;
+import nl.agilecc.agiledancers.repository.SchoolWriter;
+import nl.agilecc.agiledancers.repository.StorageException;
+import nl.agilecc.agiledancers.service.model.SchoolChange;
+
+/** Serializes short domain units of work; solver computation never holds this lock or a database connection. */
+@Singleton
+public class SchoolTransactions {
+    private final SchoolManagementService schools;
+    private final Database database;
+    private final SchoolReader reader;
+    private final SchoolWriter writer;
+
+    @Inject
+    public SchoolTransactions(
+            final SchoolManagementService schools,
+            final Database database,
+            final SchoolReader reader,
+            final SchoolWriter writer) {
+        this.schools = schools;
+        this.database = database;
+        this.reader = reader;
+        this.writer = writer;
+    }
+
+    /** An expected revision is mandatory for existing-school writes; null school identifies a new-school operation. */
+    public Object request(final Long schoolId, final Long revision, final boolean mutation, final Callable<Object> work)
+            throws Exception {
+        return request(new SchoolChange(schoolId, revision, mutation, mutation), work);
+    }
+
+    public Object request(final SchoolChange change, final Callable<Object> work) throws Exception {
+        synchronized (schools) {
+            try {
+                return database.transaction(() -> {
+                    final List<DanceSchool> before = reader.load();
+                    schools.load(before, database::nextId);
+                    if (change.mutation() && change.schoolId() != null) {
+                        check(change);
+                        schools.school(change.schoolId())
+                                .setRevision(change.revision() + (change.changesInputs() ? 1 : 0));
+                    }
+                    final Object result = work.call();
+                    if (change.changesInputs()) {
+                        store(before, change.schoolId());
+                    }
+                    return result;
+                });
+            } catch (final RevisionConflictException failure) {
+                throw new ManagementException(ManagementExceptionKind.CONFLICT, failure.getMessage());
+            } catch (final StorageException failure) {
+                throw new ManagementException(ManagementExceptionKind.STORAGE_UNAVAILABLE, failure.getMessage());
+            }
+        }
+    }
+
+    private void check(final SchoolChange change) {
+        final long schoolId = change.schoolId();
+        final Long expected = change.revision();
+        final long actual = schools.school(schoolId).getRevision();
+        if (expected == null || actual != expected) {
+            throw new ManagementException(
+                    ManagementExceptionKind.CONFLICT,
+                    "Deze school is gewijzigd of de schoolversie ontbreekt. Herlaad de gegevens en probeer opnieuw.");
+        }
+        writer.checkRevision(schoolId, expected);
+    }
+
+    private void store(final List<DanceSchool> before, final Long schoolId) {
+        final List<DanceSchool> after = schools.schools();
+        if (schoolId != null) {
+            final DanceSchool retained = after.stream()
+                    .filter((final DanceSchool school) -> school.getId().equals(schoolId))
+                    .findFirst()
+                    .orElse(null);
+            if (retained == null) {
+                writer.delete(schoolId);
+            } else {
+                writer.save(retained);
+            }
+        }
+        final List<Long> known = before.stream().map(DanceSchool::getId).toList();
+        after.stream()
+                .filter((final DanceSchool school) -> !known.contains(school.getId()))
+                .forEach(writer::save);
+    }
+
+    /** Refreshes current domain state and commits a worker's atomic result/status operation. */
+    public <T> T background(final Callable<T> work) {
+        synchronized (schools) {
+            try {
+                return database.transaction(() -> {
+                    schools.load(reader.load(), database::nextId);
+                    return work.call();
+                });
+            } catch (final RuntimeException failure) {
+                throw failure;
+            } catch (final Exception failure) {
+                throw new IllegalStateException(failure);
+            }
+        }
+    }
+
+    public void saveResult(final long schoolId) {
+        final DanceSchool school = schools.school(schoolId);
+        school.setRevision(school.getRevision() + 1);
+        writer.save(school);
+    }
+}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/service/model/ImportPreview.java

@@ -1,3 +1,4 @@
 package nl.agilecc.agiledancers.service.model;
 
-public record ImportPreview(String name, int dancers, int groups, int shows, Long existingId, String existingName) {}
+public record ImportPreview(
+        String name, int dancers, int groups, int shows, Long existingId, String existingName, Long existingRevision) {}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/service/model/SchoolChange.java

@@ -0,0 +1,4 @@
+package nl.agilecc.agiledancers.service.model;
+
+/** Run acceptance checks the loaded revision but does not itself change scheduling inputs. */
+public record SchoolChange(Long schoolId, Long revision, boolean mutation, boolean changesInputs) {}

agiledancers-be/src/main/java/nl/agilecc/agiledancers/service/port/SchedulingEngine.java

@@ -1,9 +1,15 @@
 package nl.agilecc.agiledancers.service.port;
 
+import java.util.function.Consumer;
 import nl.agilecc.agiledancers.model.scheduling.SchedulingInput;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingProgress;
 import nl.agilecc.agiledancers.model.scheduling.SchedulingResult;
 
 public interface SchedulingEngine {
     /** Computes assignments without mutating the captured inputs; the caller validates and commits the result. */
     public SchedulingResult solve(final SchedulingInput input);
+    /** Reports phase changes and solution discovery while calculating. */
+    public default SchedulingResult solve(final SchedulingInput input, final Consumer<SchedulingProgress> observer) {
+        return solve(input);
+    }
 }

agiledancers-be/src/main/java/nl/agilecc/agiledancers/solver/OrToolsSchedulingEngine.java

@@ -7,10 +7,13 @@ import com.google.ortools.sat.CpSolverStatus;
 import com.google.ortools.sat.LinearExpr;
 import jakarta.inject.Singleton;
 import java.util.List;
+import java.util.function.Consumer;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingFailureKind;
 import nl.agilecc.agiledancers.model.scheduling.SchedulingInput;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingPhase;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingProgress;
 import nl.agilecc.agiledancers.model.scheduling.SchedulingResult;
-import nl.agilecc.agiledancers.service.ManagementException;
-import nl.agilecc.agiledancers.service.ManagementExceptionKind;
+import nl.agilecc.agiledancers.service.SchedulingFailure;
 import nl.agilecc.agiledancers.service.port.SchedulingEngine;
 
 @Singleton
@@ -28,6 +31,11 @@ public class OrToolsSchedulingEngine implements SchedulingEngine {
 
     @Override
     public SchedulingResult solve(final SchedulingInput input) {
+        return solve(input, (final SchedulingProgress progress) -> {});
+    }
+
+    @Override
+    public SchedulingResult solve(final SchedulingInput input, final Consumer<SchedulingProgress> observer) {
         final long deadline = System.nanoTime() + (long) (timeLimitSeconds * 1_000_000_000L);
         Loader.loadNativeLibraries();
         final CpModel model = new CpModel();
@@ -38,7 +46,13 @@ public class OrToolsSchedulingEngine implements SchedulingEngine {
         solver.getParameters().setCatchSigintSignal(false);
         solver.getParameters().setNumSearchWorkers(1).setRandomSeed(0);
         SchedulingResult best = null;
-        for (final LinearExpr objective : List.of(attendance, LinearExpr.term(vars.spread(), 1), variety)) {
+        final List<LinearExpr> objectives = List.of(attendance, LinearExpr.term(vars.spread(), 1), variety);
+        final List<SchedulingPhase> phases =
+                List.of(SchedulingPhase.ATTENDANCE, SchedulingPhase.SPREAD, SchedulingPhase.VARIETY);
+        for (int stage = 0; stage < objectives.size(); stage++) {
+            final LinearExpr objective = objectives.get(stage);
+            final SchedulingPhase phase = phases.get(stage);
+            observer.accept(new SchedulingProgress(phase, best != null));
             final double remaining = (deadline - System.nanoTime()) / 1_000_000_000.0;
             if (remaining <= 0) {
                 if (best != null) {
@@ -48,7 +62,7 @@ public class OrToolsSchedulingEngine implements SchedulingEngine {
             }
             solver.getParameters().setMaxTimeInSeconds(Math.max(0.001, remaining));
             model.minimize(objective);
-            final CpSolverStatus status = solver.solve(model);
+            final CpSolverStatus status = solver.solve(model, new SchedulingSolutionObserver(observer, phase));
             if (status == CpSolverStatus.UNKNOWN && best != null) {
                 return new SchedulingResult(false, best.assignments());
             }
@@ -64,8 +78,12 @@ public class OrToolsSchedulingEngine implements SchedulingEngine {
 
     private static void requireSolution(final CpSolverStatus status) {
         if (status != CpSolverStatus.OPTIMAL && status != CpSolverStatus.FEASIBLE) {
-            throw new ManagementException(
-                    ManagementExceptionKind.INVALID_INPUT,
+            throw new SchedulingFailure(
+                    switch (status) {
+                        case INFEASIBLE -> SchedulingFailureKind.INFEASIBLE;
+                        case UNKNOWN -> SchedulingFailureKind.NO_SOLUTION;
+                        default -> SchedulingFailureKind.SOLVER_FAILED;
+                    },
                     switch (status) {
                         case INFEASIBLE -> "Scheduling is infeasible. Existing assignments were preserved.";
                         case UNKNOWN ->

agiledancers-be/src/main/java/nl/agilecc/agiledancers/solver/SchedulingSolutionObserver.java

@@ -0,0 +1,26 @@
+package nl.agilecc.agiledancers.solver;
+
+import com.google.ortools.sat.CpSolverSolutionCallback;
+import java.util.function.Consumer;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingPhase;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingProgress;
+
+/** Publish only the first feasible solution in a phase, avoiding an event per solver improvement. */
+public class SchedulingSolutionObserver extends CpSolverSolutionCallback {
+    private final Consumer<SchedulingProgress> observer;
+    private final SchedulingPhase phase;
+    private boolean reported;
+
+    public SchedulingSolutionObserver(final Consumer<SchedulingProgress> observer, final SchedulingPhase phase) {
+        this.observer = observer;
+        this.phase = phase;
+    }
+
+    @Override
+    public void onSolutionCallback() {
+        if (!reported) {
+            reported = true;
+            observer.accept(new SchedulingProgress(phase, true));
+        }
+    }
+}

agiledancers-be/src/main/resources/application.properties

@@ -1,7 +1,7 @@
 quarkus.application.name=agiledancers
 quarkus.http.host=0.0.0.0
 
-# Scheduling is synchronous with a 30-minute solver limit.
+# Keep idle SSE connections alive alongside the 30-minute solver limit.
 quarkus.http.idle-timeout=31M
 quarkus.jackson.fail-on-unknown-properties=true
 
@@ -9,3 +9,17 @@ quarkus.jackson.fail-on-unknown-properties=true
 %test.quarkus.jacoco.data-file=target/jacoco.exec
 %test.quarkus.jacoco.reuse-data-file=true
 %test.quarkus.jacoco.report=false
+
+# Production requires an explicitly configured database; initialization failures prevent startup.
+quarkus.datasource.db-kind=postgresql
+%prod.quarkus.datasource.jdbc.url=${DATABASE_URL}
+%prod.quarkus.datasource.username=${DATABASE_USER}
+%prod.quarkus.datasource.password=${DATABASE_PASSWORD}
+quarkus.datasource.jdbc.acquisition-timeout=5S
+quarkus.flyway.migrate-at-start=true
+quarkus.datasource.devservices.image-name=postgres:17.6
+
+# Flyway owns DDL; Hibernate validates its JPA mappings against the migrated schema.
+quarkus.hibernate-orm.schema-management.strategy=validate
+quarkus.hibernate-orm.request-scoped.enabled=false
+quarkus.datasource.jdbc.transaction-isolation-level=repeatable-read

agiledancers-be/src/main/resources/db/migration/V1__persistent_schools.sql

@@ -0,0 +1,71 @@
+CREATE SEQUENCE entity_id START 1;
+CREATE TABLE school (
+ id bigint PRIMARY KEY, school_key uuid NOT NULL UNIQUE, name text NOT NULL,
+ revision bigint NOT NULL DEFAULT 0 CHECK (revision >= 0)
+);
+CREATE TABLE dancer (
+ school_id bigint NOT NULL REFERENCES school ON DELETE CASCADE,
+ id bigint NOT NULL, name text NOT NULL, birth_date date NOT NULL,
+ PRIMARY KEY (school_id, id)
+);
+CREATE TABLE coach (
+ school_id bigint NOT NULL REFERENCES school ON DELETE CASCADE,
+ id bigint NOT NULL, name text NOT NULL, dancer_id bigint,
+ PRIMARY KEY (school_id, id),
+ FOREIGN KEY (school_id, dancer_id) REFERENCES dancer DEFERRABLE INITIALLY DEFERRED
+);
+CREATE TABLE dance_group (
+ school_id bigint NOT NULL REFERENCES school ON DELETE CASCADE,
+ id bigint NOT NULL, category text NOT NULL, group_type text NOT NULL,
+ start_age integer NOT NULL CHECK (start_age >= 0), end_age integer NOT NULL CHECK (end_age >= start_age),
+ coach_id bigint, PRIMARY KEY (school_id, id),
+ FOREIGN KEY (school_id, coach_id) REFERENCES coach DEFERRABLE INITIALLY DEFERRED
+);
+CREATE TABLE group_style (
+ school_id bigint NOT NULL, group_id bigint NOT NULL, style text NOT NULL,
+ PRIMARY KEY (school_id, group_id, style),
+ FOREIGN KEY (school_id, group_id) REFERENCES dance_group ON DELETE CASCADE
+);
+CREATE TABLE group_dancer (
+ school_id bigint NOT NULL, group_id bigint NOT NULL, dancer_id bigint NOT NULL,
+ PRIMARY KEY (school_id, group_id, dancer_id),
+ FOREIGN KEY (school_id, group_id) REFERENCES dance_group ON DELETE CASCADE,
+ FOREIGN KEY (school_id, dancer_id) REFERENCES dancer DEFERRABLE INITIALLY DEFERRED
+);
+CREATE TABLE show (
+ school_id bigint NOT NULL REFERENCES school ON DELETE CASCADE,
+ id bigint NOT NULL, name text NOT NULL, preferred_day_parts integer NOT NULL CHECK (preferred_day_parts BETWEEN 1 AND 6),
+ finalized boolean NOT NULL, PRIMARY KEY (school_id, id)
+);
+CREATE TABLE show_appearance (
+ school_id bigint NOT NULL, show_id bigint NOT NULL, group_type text NOT NULL, appearances integer NOT NULL CHECK (appearances >= 0),
+ PRIMARY KEY (school_id, show_id, group_type),
+ FOREIGN KEY (school_id, show_id) REFERENCES show ON DELETE CASCADE
+);
+CREATE TABLE day_part (
+ school_id bigint NOT NULL, show_id bigint NOT NULL, position integer NOT NULL CHECK (position >= 0),
+ day date NOT NULL, part_type text NOT NULL,
+ PRIMARY KEY (school_id, show_id, position), UNIQUE (school_id, show_id, day, part_type),
+ FOREIGN KEY (school_id, show_id) REFERENCES show ON DELETE CASCADE
+);
+CREATE TABLE assignment (
+ school_id bigint NOT NULL, show_id bigint NOT NULL, part_position integer NOT NULL,
+ position integer NOT NULL CHECK (position >= 0), group_id bigint NOT NULL,
+ PRIMARY KEY (school_id, show_id, part_position, position),
+ FOREIGN KEY (school_id, show_id, part_position) REFERENCES day_part ON DELETE CASCADE,
+ FOREIGN KEY (school_id, group_id) REFERENCES dance_group DEFERRABLE INITIALLY DEFERRED
+);
+CREATE TABLE scheduling_run (
+ school_id bigint NOT NULL REFERENCES school ON DELETE CASCADE,
+ show_id bigint NOT NULL, run_id uuid NOT NULL UNIQUE, show_name text NOT NULL,
+ started_at timestamptz NOT NULL, finished_at timestamptz,
+ state text NOT NULL CHECK (state IN ('RUNNING','OPTIMAL','VALID','STALE','INVALID_INPUT','INFEASIBLE','NO_SOLUTION','SOLVER_FAILED','INTERRUPTED')),
+ phase text NOT NULL CHECK (phase IN ('PREPARING','ATTENDANCE','SPREAD','VARIETY')),
+ feasible boolean NOT NULL, message text NOT NULL,
+ attendance_excess bigint, performance_spread integer, variety_penalty bigint,
+ PRIMARY KEY (school_id, show_id),
+ FOREIGN KEY (school_id, show_id) REFERENCES show DEFERRABLE INITIALLY DEFERRED,
+ CHECK ((state = 'RUNNING') = (finished_at IS NULL)),
+ CHECK ((attendance_excess IS NULL AND performance_spread IS NULL AND variety_penalty IS NULL)
+     OR (attendance_excess IS NOT NULL AND performance_spread IS NOT NULL AND variety_penalty IS NOT NULL))
+);

agiledancers-be/src/main/resources/db/migration/V2__jpa_aggregate_versioning.sql

@@ -0,0 +1,15 @@
+-- Child-only edits must dirty the school entity so @Version advances exactly once.
+ALTER TABLE school ADD COLUMN change_stamp bigint NOT NULL DEFAULT 0;
+
+-- Keep existing identifiers and start above every value already allocated by V1.
+-- JPA allocates identifiers under a row lock, including when a transaction creates a whole import graph.
+CREATE TABLE entity_identifiers (
+ id integer PRIMARY KEY CHECK (id = 1),
+ next_value bigint NOT NULL CHECK (next_value > 0)
+);
+INSERT INTO entity_identifiers (id, next_value) VALUES (1, nextval('entity_id'));
+
+-- Hibernate updates retained positions in place; date/type swaps must be checked on the final graph.
+ALTER TABLE day_part DROP CONSTRAINT day_part_school_id_show_id_day_part_type_key;
+ALTER TABLE day_part ADD CONSTRAINT day_part_date_type_unique
+ UNIQUE (school_id, show_id, day, part_type) DEFERRABLE INITIALLY DEFERRED;

agiledancers-be/src/test/java/nl/agilecc/agiledancers/DomainViewMapperTest.java

@@ -0,0 +1,119 @@
+package nl.agilecc.agiledancers;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import io.quarkus.test.junit.QuarkusTest;
+import jakarta.inject.Inject;
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import nl.agilecc.agiledancers.model.Coach;
+import nl.agilecc.agiledancers.model.DanceGroup;
+import nl.agilecc.agiledancers.model.DanceSchool;
+import nl.agilecc.agiledancers.model.Dancer;
+import nl.agilecc.agiledancers.model.DayPart;
+import nl.agilecc.agiledancers.model.Show;
+import nl.agilecc.agiledancers.model.specifications.DanceGroupStyle;
+import nl.agilecc.agiledancers.model.specifications.DayPartType;
+import nl.agilecc.agiledancers.rest.apimodel.GroupView;
+import nl.agilecc.agiledancers.rest.apimodel.SchoolView;
+import nl.agilecc.agiledancers.rest.apimodel.ShowView;
+import nl.agilecc.agiledancers.rest.mapping.DomainViewMapper;
+import org.junit.jupiter.api.Test;
+
+@QuarkusTest
+class DomainViewMapperTest {
+    private @Inject DomainViewMapper views;
+
+    public @Test void relationshipsBecomeOrderedIdsAndUnlinkedCoachesRetainNull() {
+        final DanceSchool school =
+                DanceSchool.builder().name("School").revision(4).build();
+        school.setId(7L);
+        final Dancer first = dancer(9L);
+        final Dancer second = dancer(3L);
+        school.addDancer(first);
+        school.addDancer(second);
+        final SchoolView mapped = views.school(school);
+        assertEquals(List.of(9L, 3L), mapped.dancerIds());
+        assertEquals(4, mapped.revision());
+        final Coach coach = Coach.builder().name("Coach").dancer(first).build();
+        coach.setId(2L);
+        assertEquals(9L, views.coach(coach).dancerId());
+        coach.setDancer(null);
+        assertNull(views.coach(coach).dancerId());
+        school.removeDancer(first);
+        assertEquals(List.of(9L, 3L), mapped.dancerIds());
+        assertThrows(
+                UnsupportedOperationException.class, () -> mapped.dancerIds().clear());
+    }
+
+    public @Test void nestedViewsKeepAssignmentOrderAndExplicitValidationWithoutSharingCollections() {
+        final DanceGroup first = DanceGroup.builder().category("First").build();
+        first.setId(8L);
+        final DanceGroup second = DanceGroup.builder().category("Second").build();
+        second.setId(2L);
+        final List<DanceGroup> assigned = new ArrayList<>(List.of(first, second));
+        final DayPart part = DayPart.builder()
+                .date(LocalDate.of(2027, 1, 1))
+                .type(DayPartType.MORNING)
+                .danceGroups(assigned)
+                .build();
+        final List<String> violations = new ArrayList<>(List.of("Draft validation"));
+        final Show show = Show.builder()
+                .name("Show")
+                .dayParts(new ArrayList<>(List.of(part)))
+                .appearances(Map.of())
+                .build();
+        show.setId(1L);
+        final ShowView mapped = views.show(show, violations);
+        assertEquals(1, mapped.preferredDayParts());
+        assertEquals(List.of(8L, 2L), mapped.dayParts().getFirst().danceGroupIds());
+        assigned.clear();
+        violations.clear();
+        show.getDayParts().clear();
+        assertEquals(List.of(8L, 2L), mapped.dayParts().getFirst().danceGroupIds());
+        assertEquals(List.of("Draft validation"), mapped.violations());
+        assertThrows(
+                UnsupportedOperationException.class,
+                () -> mapped.dayParts().getFirst().danceGroupIds().clear());
+    }
+
+    public @Test void preferredDefaultsUseTheExistingRuleAndStylesAreSnapshotValues() {
+        final DayPart part = DayPart.builder()
+                .date(LocalDate.of(2027, 1, 1))
+                .type(DayPartType.MORNING)
+                .danceGroups(List.of())
+                .build();
+        final Show show = Show.builder()
+                .dayParts(List.of(part, part))
+                .appearances(Map.of())
+                .build();
+        show.setId(1L);
+        assertEquals(2, views.show(show, List.of()).preferredDayParts());
+        show.setPreferredDayParts(1);
+        assertEquals(1, views.show(show, List.of()).preferredDayParts());
+        final DanceGroup group = DanceGroup.builder().category("Group").build();
+        group.setId(1L);
+        group.addStyle(DanceGroupStyle.JAZZ);
+        final Dancer dancer = dancer(4L);
+        group.addDancer(dancer);
+        final GroupView mapped = views.group(group);
+        group.replaceStyles(Set.of(DanceGroupStyle.MODERN));
+        group.removeDancer(dancer);
+        assertEquals(Set.of(DanceGroupStyle.JAZZ), mapped.styles());
+        assertEquals(List.of(4L), mapped.dancerIds());
+    }
+
+    private static Dancer dancer(final long id) {
+        final Dancer dancer = Dancer.builder()
+                .name("Dancer")
+                .birthDate(LocalDate.of(2000, 1, 1))
+                .build();
+        dancer.setId(id);
+        return dancer;
+    }
+}

agiledancers-be/src/test/java/nl/agilecc/agiledancers/PersistenceTest.java

@@ -0,0 +1,386 @@
+package nl.agilecc.agiledancers;
+
+import static io.restassured.RestAssured.given;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import io.quarkus.test.junit.QuarkusTest;
+import jakarta.inject.Inject;
+import java.time.LocalDate;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import nl.agilecc.agiledancers.model.DanceSchool;
+import nl.agilecc.agiledancers.model.DayPart;
+import nl.agilecc.agiledancers.model.Show;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingPhase;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingProgress;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingRun;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingState;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingSummary;
+import nl.agilecc.agiledancers.model.specifications.DanceGroupStyle;
+import nl.agilecc.agiledancers.model.specifications.DanceGroupType;
+import nl.agilecc.agiledancers.model.specifications.DayPartType;
+import nl.agilecc.agiledancers.repository.Database;
+import nl.agilecc.agiledancers.repository.RunRepository;
+import nl.agilecc.agiledancers.repository.SchoolReader;
+import nl.agilecc.agiledancers.repository.SchoolWriter;
+import nl.agilecc.agiledancers.repository.StorageException;
+import nl.agilecc.agiledancers.service.SchoolManagementService;
+import nl.agilecc.agiledancers.service.SchoolTransactions;
+import nl.agilecc.agiledancers.service.model.GroupDetails;
+import org.junit.jupiter.api.Test;
+
+@QuarkusTest
+class PersistenceTest {
+    private @Inject SchoolTransactions transactions;
+    private @Inject SchoolManagementService schools;
+    private @Inject Database database;
+    private @Inject SchoolReader reader;
+    private @Inject SchoolWriter writer;
+    private @Inject RunRepository runs;
+    private @Inject jakarta.persistence.EntityManager entities;
+
+    public @Test void simultaneousEditsRequireTheLoadedRevision() throws Exception {
+        final long id = create();
+        final String path = "/api/dance-schools/" + id;
+        try (final java.util.concurrent.ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) {
+            final java.util.concurrent.Future<Integer> first = executor.submit(() -> rename(path, "First", 0));
+            final java.util.concurrent.Future<Integer> second = executor.submit(() -> rename(path, "Second", 0));
+            final List<Integer> statuses = List.of(first.get(10, TimeUnit.SECONDS), second.get(10, TimeUnit.SECONDS));
+            assertTrue(statuses.containsAll(List.of(200, 409)));
+            given().contentType("application/json")
+                    .body("{\"name\":\"Missing revision\"}")
+                    .put(path)
+                    .then()
+                    .statusCode(409);
+            given().get(path + "/data").then().statusCode(200);
+            assertEquals(1, given().get(path).jsonPath().getInt("revision"));
+        } finally {
+            delete(id);
+        }
+    }
+
+    public @Test void detachedRelationalGraphRetainsIdsReferencesDraftAndFinalState() throws Exception {
+        final long id = create();
+        try {
+            final Show show = fixture(id);
+            transactions.background(() -> {
+                final DanceSchool loaded = schools.school(id);
+                assertEquals(1, loaded.getDancers().size());
+                assertEquals(
+                        Set.of(DanceGroupStyle.JAZZ),
+                        loaded.getDanceGroups().iterator().next().getStyles());
+                assertEquals(show.getId(), loaded.getShows().iterator().next().getId());
+                assertTrue(loaded.getShows().iterator().next().isFinalized());
+                assertEquals(
+                        loaded.getDanceGroups().iterator().next(),
+                        loaded.getShows()
+                                .iterator()
+                                .next()
+                                .getDayParts()
+                                .getFirst()
+                                .getDanceGroups()
+                                .getFirst());
+                return null;
+            });
+            given().get("/api/dance-schools/" + id + "/export").then().statusCode(200);
+        } finally {
+            delete(id);
+        }
+    }
+
+    public @Test void deferredConstraintFailureRollsBackDomainAndCompletedStatusTogether() throws Exception {
+        final long id = create();
+        try {
+            final Show show = fixture(id);
+            final SchedulingRun run = SchedulingRun.started(id, show.getId(), show.getName());
+            database.transaction(() -> {
+                runs.save(run);
+                return null;
+            });
+            final java.util.concurrent.atomic.AtomicBoolean published = new java.util.concurrent.atomic.AtomicBoolean();
+            assertThrows(StorageException.class, () -> damageResult(id, show, run, published));
+            assertFalse(published.get());
+            database.transaction(() -> {
+                assertEquals(
+                        "Persistent school",
+                        reader.load().stream()
+                                .filter((final DanceSchool school) -> school.getId() == id)
+                                .findFirst()
+                                .orElseThrow()
+                                .getName());
+                assertEquals(
+                        1,
+                        entities.find(
+                                        nl.agilecc.agiledancers.repository.entity.DayPartEntity.class,
+                                        new nl.agilecc.agiledancers.repository.entity.DayPartId(id, show.getId(), 0))
+                                .getGroupIds()
+                                .size());
+                assertEquals(
+                        SchedulingState.RUNNING,
+                        runs.load().stream()
+                                .filter((final SchedulingRun item) ->
+                                        item.runId().equals(run.runId()))
+                                .findFirst()
+                                .orElseThrow()
+                                .state());
+                return null;
+            });
+        } finally {
+            delete(id);
+        }
+    }
+
+    public @Test void recoveryRetainsRunIdentityProgressAndExistingAssignments() throws Exception {
+        final long id = create();
+        try {
+            final Show show = fixture(id);
+            final SchedulingRun run = SchedulingRun.started(id, show.getId(), show.getName())
+                    .progressed(new SchedulingProgress(SchedulingPhase.SPREAD, true));
+            database.transaction(() -> {
+                runs.save(run);
+                return null;
+            });
+            database.transaction(() -> {
+                runs.recover();
+                return null;
+            });
+            database.transaction(() -> {
+                final SchedulingRun recovered = runs.load().stream()
+                        .filter((final SchedulingRun item) -> item.runId().equals(run.runId()))
+                        .findFirst()
+                        .orElseThrow();
+                assertEquals(SchedulingState.INTERRUPTED, recovered.state());
+                assertEquals(run.progress(), recovered.progress());
+                assertTrue(recovered.finishedAt() != null);
+                assertTrue(recovered.message().contains("behouden"));
+                return null;
+            });
+        } finally {
+            delete(id);
+        }
+    }
+
+    public @Test void aFailedReplacementImportRetainsThePreviousGraphAndRevision() throws Exception {
+        final long id = create();
+        try {
+            fixture(id);
+            final nl.agilecc.agiledancers.service.model.SchoolSnapshot before =
+                    transactions.background(() -> schools.exportSchool(id));
+            assertThrows(
+                    nl.agilecc.agiledancers.service.ManagementException.class,
+                    () -> transactions.request(id, 1L, true, () -> {
+                        final DanceSchool imported = schools.importSchool(before, id);
+                        imported.getDancers().iterator().next().setBirthDate(null);
+                        return imported;
+                    }));
+            transactions.background(() -> {
+                assertEquals(before, schools.exportSchool(id));
+                assertEquals(1, schools.school(id).getRevision());
+                return null;
+            });
+        } finally {
+            delete(id);
+        }
+    }
+
+    public @Test void changedSchoolInputsRejectAnOlderSolverSnapshot() throws Exception {
+        final long id = create();
+        try {
+            final Show show = fixture(id);
+            final nl.agilecc.agiledancers.model.scheduling.SchedulingInput input =
+                    transactions.background(() -> schools.beginScheduling(id, show.getId()));
+            transactions.request(id, 1L, true, () -> schools.updateSchool(id, "Changed"));
+            final nl.agilecc.agiledancers.service.ManagementException failure = assertThrows(
+                    nl.agilecc.agiledancers.service.ManagementException.class,
+                    () -> transactions.background(() -> {
+                        schools.finishScheduling(
+                                id,
+                                input,
+                                new nl.agilecc.agiledancers.model.scheduling.SchedulingResult(
+                                        true, List.of(List.of())));
+                        return null;
+                    }));
+            assertEquals(nl.agilecc.agiledancers.service.ManagementExceptionKind.CONFLICT, failure.getKind());
+            transactions.background(() -> {
+                assertEquals(
+                        1,
+                        schools.show(id, show.getId())
+                                .getDayParts()
+                                .getFirst()
+                                .getDanceGroups()
+                                .size());
+                schools.endScheduling(show.getId());
+                return null;
+            });
+        } finally {
+            delete(id);
+        }
+    }
+
+    public @Test void hibernateVersionRejectsDetachedStaleEntities() throws Exception {
+        final long id = create();
+        try {
+            final nl.agilecc.agiledancers.repository.entity.SchoolEntity stale = database.transaction(
+                    () -> entities.find(nl.agilecc.agiledancers.repository.entity.SchoolEntity.class, id));
+            database.transaction(() -> {
+                entities.find(nl.agilecc.agiledancers.repository.entity.SchoolEntity.class, id)
+                        .setName("Confirmed");
+                return null;
+            });
+            stale.setName("Stale");
+            assertThrows(
+                    nl.agilecc.agiledancers.repository.RevisionConflictException.class,
+                    () -> database.transaction(() -> entities.merge(stale)));
+            transactions.background(() -> {
+                assertEquals("Confirmed", schools.school(id).getName());
+                assertEquals(1, schools.school(id).getRevision());
+                return null;
+            });
+        } finally {
+            delete(id);
+        }
+    }
+
+    public @Test void childOnlyEditsAdvanceTheAggregateVersionOnce() throws Exception {
+        final long id = create();
+        try {
+            fixture(id);
+            transactions.request(id, 1L, true, () -> {
+                final long dancerId = schools.dancers(id).getFirst().getId();
+                return schools.updateDancer(id, dancerId, "Updated dancer", LocalDate.of(2000, 1, 1));
+            });
+            transactions.background(() -> {
+                assertEquals(2, schools.school(id).getRevision());
+                assertEquals("Updated dancer", schools.dancers(id).getFirst().getName());
+                return null;
+            });
+        } finally {
+            delete(id);
+        }
+    }
+
+    public @Test void hibernateRetainsAssignmentsWhenDayPartsAreReordered() throws Exception {
+        final long id = create();
+        try {
+            final Show show = fixture(id);
+            final DayPart added = DayPart.builder()
+                    .date(LocalDate.of(2027, 1, 2))
+                    .type(DayPartType.EVENING)
+                    .danceGroups(List.of())
+                    .build();
+            transactions.request(
+                    id,
+                    1L,
+                    true,
+                    () -> schools.updateShow(
+                            id,
+                            show.getId(),
+                            "Two parts",
+                            List.of(show.getDayParts().getFirst(), added),
+                            null));
+            transactions.request(id, 2L, true, () -> {
+                final Show current = schools.show(id, show.getId());
+                return schools.updateShow(
+                        id,
+                        show.getId(),
+                        "Swapped",
+                        List.of(
+                                current.getDayParts().getLast(),
+                                current.getDayParts().getFirst()),
+                        null);
+            });
+            transactions.background(() -> {
+                final Show restored = schools.show(id, show.getId());
+                assertEquals(added.getDate(), restored.getDayParts().getFirst().getDate());
+                assertEquals(
+                        1, restored.getDayParts().getLast().getDanceGroups().size());
+                assertEquals(3, schools.school(id).getRevision());
+                return null;
+            });
+        } finally {
+            delete(id);
+        }
+    }
+
+    private void damageResult(
+            final long id,
+            final Show show,
+            final SchedulingRun run,
+            final java.util.concurrent.atomic.AtomicBoolean published)
+            throws Exception {
+        database.transaction(() -> {
+            entities.find(nl.agilecc.agiledancers.repository.entity.SchoolEntity.class, id)
+                    .setName("Uncommitted");
+            entities.find(
+                            nl.agilecc.agiledancers.repository.entity.DayPartEntity.class,
+                            new nl.agilecc.agiledancers.repository.entity.DayPartId(id, show.getId(), 0))
+                    .getGroupIds()
+                    .clear();
+            runs.save(run.completed(SchedulingState.OPTIMAL, "Uncommitted", new SchedulingSummary(0, 0, 0)));
+            database.afterCommit(() -> published.set(true));
+            // This dancer FK is deferred: work returns normally, and commit itself must fail.
+            entities.find(
+                            nl.agilecc.agiledancers.repository.entity.GroupEntity.class,
+                            new nl.agilecc.agiledancers.repository.entity.SchoolMemberId(
+                                    id,
+                                    show.getDayParts()
+                                            .getFirst()
+                                            .getDanceGroups()
+                                            .getFirst()
+                                            .getId()))
+                    .getDancerIds()
+                    .add(999999L);
+            return null;
+        });
+    }
+
+    private long create() throws Exception {
+        return (Long) transactions.request(
+                null,
+                null,
+                true,
+                () -> schools.createSchool("Persistent school").getId());
+    }
+
+    private Show fixture(final long id) throws Exception {
+        return (Show) transactions.request(id, 0L, true, () -> {
+            final long dancer =
+                    schools.createDancer(id, "Dancer", LocalDate.of(2000, 1, 1)).getId();
+            final long group = schools.createGroup(
+                            id, new GroupDetails("Group", DanceGroupType.REGULAR, 0, 99, Set.of(DanceGroupStyle.JAZZ)))
+                    .getId();
+            schools.addGroupDancer(id, group, dancer);
+            final Show show = schools.createShow(
+                    id,
+                    "Saved show",
+                    List.of(DayPart.builder()
+                            .date(LocalDate.of(2027, 1, 1))
+                            .type(DayPartType.MORNING)
+                            .danceGroups(List.of(schools.group(id, group)))
+                            .build()),
+                    null);
+            show.setFinalized(true);
+            return show;
+        });
+    }
+
+    private int rename(final String path, final String name, final long revision) {
+        return given().header("X-School-Revision", revision)
+                .contentType("application/json")
+                .body(java.util.Map.of("name", name))
+                .put(path)
+                .statusCode();
+    }
+
+    private void delete(final long id) {
+        transactions.background(() -> {
+            writer.delete(id);
+            return null;
+        });
+    }
+}

agiledancers-be/src/test/java/nl/agilecc/agiledancers/RevisionRequests.java

@@ -0,0 +1,50 @@
+package nl.agilecc.agiledancers;
+
+import io.restassured.RestAssured;
+import io.restassured.response.Response;
+import io.restassured.specification.FilterableRequestSpecification;
+import io.restassured.specification.RequestSpecification;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/** Existing endpoint scenarios use fresh revisions; concurrency tests deliberately send explicit stale revisions. */
+public class RevisionRequests {
+    private static final Pattern SCHOOL = Pattern.compile("/api/dance-schools/(\\d+)(?:/|$)");
+    private static final Pattern REPLACEMENT = Pattern.compile("[?&]replaceId=(\\d+)");
+
+    public static RequestSpecification given() {
+        return RestAssured.given()
+                .filter(
+                        (final FilterableRequestSpecification request,
+                                final io.restassured.specification.FilterableResponseSpecification response,
+                                final io.restassured.filter.FilterContext context) -> {
+                            addRevision(request);
+                            return context.next(request, response);
+                        });
+    }
+
+    private static void addRevision(final FilterableRequestSpecification request) {
+        final String id = schoolId(request);
+        if (!request.getMethod().equals("GET")
+                && id != null
+                && !request.getHeaders().hasHeaderWithName("X-School-Revision")) {
+            final Response school = RestAssured.given().get("/api/dance-schools/" + id);
+            if (school.statusCode() == 200) {
+                request.header("X-School-Revision", school.jsonPath().getLong("revision"));
+            }
+        }
+    }
+
+    private static String schoolId(final FilterableRequestSpecification request) {
+        final Matcher school = SCHOOL.matcher(request.getURI());
+        if (school.find()) {
+            return school.group(1);
+        }
+        final Matcher replacement = REPLACEMENT.matcher(request.getURI());
+        if (replacement.find()) {
+            return replacement.group(1);
+        }
+        final Object parameter = request.getQueryParams().get("replaceId");
+        return parameter == null ? null : parameter.toString();
+    }
+}

agiledancers-be/src/test/java/nl/agilecc/agiledancers/S18ResourceTest.java

@@ -1,6 +1,6 @@
 package nl.agilecc.agiledancers;
 
-import static io.restassured.RestAssured.given;
+import static nl.agilecc.agiledancers.RevisionRequests.given;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.hasSize;
@@ -92,7 +92,8 @@ class S18ResourceTest {
             final long dancer = dancer(school, "Coach");
             group(school, dancer);
             final String show = show(school);
-            given().post(show + "/schedule").then().statusCode(200);
+            given().post(show + "/schedule").then().statusCode(202);
+            awaitScheduling(show);
             given().post(show + "/finalize").then().statusCode(200);
             final long coach = given().contentType("application/json")
                     .body(Map.of("dancerId", dancer))
@@ -133,4 +134,13 @@ class S18ResourceTest {
             given().delete(school).then().statusCode(204);
         }
     }
+
+    private static void awaitScheduling(final String show) {
+        final long deadline = System.nanoTime() + java.util.concurrent.TimeUnit.SECONDS.toNanos(15);
+        while ("RUNNING".equals(given().get(show + "/schedule").jsonPath().getString("state"))
+                && System.nanoTime() < deadline) {
+            java.util.concurrent.locks.LockSupport.parkNanos(java.util.concurrent.TimeUnit.MILLISECONDS.toNanos(20));
+        }
+        given().get(show + "/schedule").then().statusCode(200).body("state", equalTo("OPTIMAL"));
+    }
 }

agiledancers-be/src/test/java/nl/agilecc/agiledancers/SchedulingEventsTest.java

@@ -0,0 +1,143 @@
+package nl.agilecc.agiledancers;
+
+import static nl.agilecc.agiledancers.RevisionRequests.given;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.quarkus.test.common.http.TestHTTPResource;
+import io.quarkus.test.junit.QuarkusTest;
+import jakarta.inject.Inject;
+import java.io.BufferedReader;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.nio.charset.StandardCharsets;
+import java.time.LocalDate;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import nl.agilecc.agiledancers.model.DayPart;
+import nl.agilecc.agiledancers.model.Show;
+import nl.agilecc.agiledancers.model.specifications.DanceGroupType;
+import nl.agilecc.agiledancers.model.specifications.DayPartType;
+import nl.agilecc.agiledancers.service.SchoolManagementService;
+import nl.agilecc.agiledancers.service.model.GroupDetails;
+import org.junit.jupiter.api.Test;
+
+@QuarkusTest
+class SchedulingEventsTest {
+    private @Inject SchoolManagementService schools;
+    private @Inject ObjectMapper json;
+    private @Inject nl.agilecc.agiledancers.service.SchoolTransactions transactions;
+    private @TestHTTPResource URI base;
+
+    public @Test void streamStartsWithSnapshotAndPushesCompletionAndReconnectSnapshot() throws Exception {
+        final long school = (Long) transactions.request(
+                null, null, true, () -> schools.createSchool("SSE school").getId());
+        try {
+            final Show show = (Show) transactions.request(school, 0L, true, () -> show(school));
+            final String path = "/api/dance-schools/" + school + "/shows/" + show.getId() + "/schedule";
+            given().get(path).then().statusCode(204);
+            try (final HttpClient client = HttpClient.newHttpClient();
+                    final ExecutorService executor = Executors.newSingleThreadExecutor();
+                    final InputStream stream = stream(client);
+                    final BufferedReader reader =
+                            new BufferedReader(new InputStreamReader(stream, StandardCharsets.UTF_8))) {
+                assertNotNull(next(reader).get("runs"));
+                final String runId = given().post(path)
+                        .then()
+                        .statusCode(202)
+                        .extract()
+                        .jsonPath()
+                        .getString("runId");
+                final JsonNode completion =
+                        executor.submit(() -> completion(reader, runId)).get(15, TimeUnit.SECONDS);
+                assertEquals("OPTIMAL", completion.get("state").asText());
+                assertTrue(completion.get("progress").get("feasible").asBoolean());
+                given().get(path).then().statusCode(200);
+            }
+            assertReconnectContains(show.getId());
+        } finally {
+            given().delete("/api/dance-schools/" + school);
+        }
+    }
+
+    private void assertReconnectContains(final long showId) throws Exception {
+        try (final HttpClient client = HttpClient.newHttpClient();
+                final InputStream stream = stream(client);
+                final BufferedReader reader =
+                        new BufferedReader(new InputStreamReader(stream, StandardCharsets.UTF_8))) {
+            final JsonNode runs = next(reader).get("runs");
+            boolean found = false;
+            for (final JsonNode run : runs) {
+                if (run.get("showId").asLong() == showId) {
+                    assertEquals("OPTIMAL", run.get("state").asText());
+                    found = true;
+                }
+            }
+            assertTrue(found);
+        }
+    }
+
+    private InputStream stream(final HttpClient client) throws Exception {
+        final HttpResponse<InputStream> response = client.send(
+                HttpRequest.newBuilder(base.resolve("/api/scheduling/events"))
+                        .header("Accept", "text/event-stream")
+                        .build(),
+                HttpResponse.BodyHandlers.ofInputStream());
+        assertEquals(200, response.statusCode());
+        assertTrue(response.headers().firstValue("content-type").orElse("").startsWith("text/event-stream"));
+        return response.body();
+    }
+
+    private JsonNode completion(final BufferedReader reader, final String runId) throws Exception {
+        while (true) {
+            final JsonNode event = next(reader);
+            if (event.get("runs").isNull()) {
+                continue;
+            }
+            for (final JsonNode run : event.get("runs")) {
+                if (run.get("runId").asText().equals(runId)
+                        && !run.get("state").asText().equals("RUNNING")) {
+                    return run;
+                }
+            }
+        }
+    }
+
+    private JsonNode next(final BufferedReader reader) throws Exception {
+        String line = reader.readLine();
+        while (line != null && !line.startsWith("data:")) {
+            line = reader.readLine();
+        }
+        assertNotNull(line);
+        return json.readTree(line.substring(5).trim());
+    }
+
+    private Show show(final long school) {
+        final long group = schools.createGroup(
+                        school, new GroupDetails("Group", DanceGroupType.REGULAR, 0, 99, Set.of()))
+                .getId();
+        schools.addGroupDancer(
+                school,
+                group,
+                schools.createDancer(school, "Dancer", LocalDate.of(2000, 1, 1)).getId());
+        return schools.createShow(
+                school,
+                "Show",
+                List.of(DayPart.builder()
+                        .date(LocalDate.of(2027, 1, 1))
+                        .type(DayPartType.MORNING)
+                        .danceGroups(List.of())
+                        .build()),
+                null);
+    }
+}

agiledancers-be/src/test/java/nl/agilecc/agiledancers/SchedulingProgressTest.java

@@ -0,0 +1,61 @@
+package nl.agilecc.agiledancers;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import nl.agilecc.agiledancers.model.scheduling.GroupRequirement;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingFailureKind;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingInput;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingPhase;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingProgress;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingResult;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingSummary;
+import nl.agilecc.agiledancers.model.scheduling.VarietyScore;
+import nl.agilecc.agiledancers.model.specifications.DanceGroupStyle;
+import nl.agilecc.agiledancers.service.SchedulingFailure;
+import nl.agilecc.agiledancers.solver.OrToolsSchedulingEngine;
+import org.junit.jupiter.api.Test;
+
+class SchedulingProgressTest {
+    public @Test void realSolverReportsDiscoveryDuringEachPhase() {
+        final SchedulingInput input = new SchedulingInput(1, 0, 2, List.of(new GroupRequirement(2, 1)));
+        final List<SchedulingProgress> updates = new ArrayList<>();
+        final SchedulingResult result = new OrToolsSchedulingEngine().solve(input, updates::add);
+        assertTrue(result.optimal());
+        assertEquals(
+                List.of(SchedulingPhase.ATTENDANCE, SchedulingPhase.SPREAD, SchedulingPhase.VARIETY),
+                updates.stream().map(SchedulingProgress::phase).distinct().toList());
+        assertEquals(new SchedulingProgress(SchedulingPhase.ATTENDANCE, false), updates.getFirst());
+        assertTrue(updates.contains(new SchedulingProgress(SchedulingPhase.ATTENDANCE, true)));
+        assertTrue(updates.contains(new SchedulingProgress(SchedulingPhase.VARIETY, true)));
+    }
+
+    public @Test void noSolutionAndInfeasibleHaveStableDistinctOutcomes() {
+        final SchedulingInput input = new SchedulingInput(1, 0, 1, List.of(new GroupRequirement(2, 1)));
+        assertEquals(
+                SchedulingFailureKind.NO_SOLUTION,
+                assertThrows(SchedulingFailure.class, () -> new OrToolsSchedulingEngine(0).solve(input))
+                        .getOutcome());
+        final SchedulingInput impossible = new SchedulingInput(1, 0, 1, List.of(new GroupRequirement(2, 2)));
+        assertEquals(
+                SchedulingFailureKind.INFEASIBLE,
+                assertThrows(SchedulingFailure.class, () -> new OrToolsSchedulingEngine().solve(impossible))
+                        .getOutcome());
+    }
+
+    public @Test void summaryMatchesTheThreeObjectiveDefinitionsAndCoachExemptions() {
+        final GroupRequirement showcase = new GroupRequirement(1, 1, true, Set.of(10L, 11L), Set.of(), 20);
+        final GroupRequirement regular =
+                new GroupRequirement(2, 2, false, Set.of(10L, 11L), Set.of(DanceGroupStyle.MODERN), 22);
+        final SchedulingInput input = new SchedulingInput(1, 0, 3, List.of(showcase, regular), 1, Set.of(11L));
+        final SchedulingResult result = new SchedulingResult(false, List.of(List.of(1L, 2L), List.of(2L), List.of()));
+        final SchedulingSummary summary = SchedulingSummary.of(input, result);
+        assertEquals(1, summary.attendanceExcess());
+        assertEquals(2, summary.performanceSpread());
+        assertEquals(VarietyScore.penalty(showcase, regular), summary.varietyPenalty());
+    }
+}

agiledancers-be/src/test/java/nl/agilecc/agiledancers/SchoolManagementResourceTest.java

@@ -1,6 +1,6 @@
 package nl.agilecc.agiledancers;
 
-import static io.restassured.RestAssured.given;
+import static nl.agilecc.agiledancers.RevisionRequests.given;
 import static org.hamcrest.Matchers.contains;
 import static org.hamcrest.Matchers.containsInAnyOrder;
 import static org.hamcrest.Matchers.empty;
@@ -175,7 +175,8 @@ class SchoolManagementResourceTest {
             given().put(school + "/dance-groups/" + group + "/dancers/" + dancer)
                     .then()
                     .statusCode(204);
-            given().post(show + "/schedule").then().statusCode(200).body("optimal", equalTo(true));
+            given().post(show + "/schedule").then().statusCode(202).body("state", equalTo("RUNNING"));
+            awaitScheduling(show);
             given().get(show).then().body("dayParts[0].danceGroupIds", contains((int) group));
             final String before = given().get(show).asString();
             for (final String count : new String[] {"0", "2", "1.5", "7"}) {
@@ -291,4 +292,13 @@ class SchoolManagementResourceTest {
     private static ValidatableResponse put(final String path, final Object body) {
         return given().contentType("application/json").body(body).put(path).then();
     }
+
+    private static void awaitScheduling(final String show) {
+        final long deadline = System.nanoTime() + java.util.concurrent.TimeUnit.SECONDS.toNanos(15);
+        while ("RUNNING".equals(given().get(show + "/schedule").jsonPath().getString("state"))
+                && System.nanoTime() < deadline) {
+            java.util.concurrent.locks.LockSupport.parkNanos(java.util.concurrent.TimeUnit.MILLISECONDS.toNanos(20));
+        }
+        given().get(show + "/schedule").then().statusCode(200).body("state", equalTo("OPTIMAL"));
+    }
 }

agiledancers-be/src/test/java/nl/agilecc/agiledancers/SchoolSnapshotResourceTest.java

@@ -1,6 +1,6 @@
 package nl.agilecc.agiledancers;
 
-import static io.restassured.RestAssured.given;
+import static nl.agilecc.agiledancers.RevisionRequests.given;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.emptyOrNullString;
 import static org.hamcrest.Matchers.equalTo;

agiledancers-be/src/test/java/nl/agilecc/agiledancers/service/SchedulingRunsTest.java

@@ -0,0 +1,247 @@
+package nl.agilecc.agiledancers.service;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.locks.LockSupport;
+import nl.agilecc.agiledancers.model.DayPart;
+import nl.agilecc.agiledancers.model.Show;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingFailureKind;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingInput;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingResult;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingRun;
+import nl.agilecc.agiledancers.model.scheduling.SchedulingState;
+import nl.agilecc.agiledancers.model.specifications.DanceGroupType;
+import nl.agilecc.agiledancers.model.specifications.DayPartType;
+import nl.agilecc.agiledancers.service.model.GroupDetails;
+import nl.agilecc.agiledancers.service.port.SchedulingEngine;
+import nl.agilecc.agiledancers.solver.OrToolsSchedulingEngine;
+import org.junit.jupiter.api.Test;
+
+class SchedulingRunsTest {
+    private final SchoolManagementService schools = new SchoolManagementService();
+    private final long school = schools.createSchool("School").getId();
+
+    public @Test void startsInBackgroundRejectsDuplicatesAndRecoversCurrentStatus() throws Exception {
+        final Show show = show();
+        final var entered = new CountDownLatch(1);
+        final var release = new CountDownLatch(1);
+        final var updates = new AtomicReference<List<SchedulingRun>>();
+        final var runs = new SchedulingRuns(schools, blocking(entered, release));
+        try {
+            final Runnable unsubscribe = runs.subscribe(updates::set);
+            assertTrue(updates.get().isEmpty());
+            final SchedulingRun started = runs.start(school, show.getId());
+            assertEquals(SchedulingState.RUNNING, started.state());
+            assertTrue(entered.await(10, TimeUnit.SECONDS));
+            assertEquals(started, runs.status(school, show.getId()));
+            assertThrows(ManagementException.class, () -> runs.start(school, show.getId()));
+            unsubscribe.run();
+            final var reconnect = new AtomicReference<List<SchedulingRun>>();
+            final Runnable disconnect = runs.subscribe(reconnect::set);
+            assertEquals(started, reconnect.get().getFirst());
+            release.countDown();
+            final SchedulingRun finished = await(runs, show);
+            assertEquals(SchedulingState.OPTIMAL, finished.state());
+            assertEquals(0, finished.summary().performanceSpread());
+            assertTrue(finished.progress().feasible());
+            assertTrue(finished.finishedAt().compareTo(finished.startedAt()) >= 0);
+            assertFalse(show.getDayParts().getFirst().getDanceGroups().isEmpty());
+            assertEquals(SchedulingState.RUNNING, updates.get().getFirst().state());
+            disconnect.run();
+            assertNotEquals(started.runId(), runs.start(school, show.getId()).runId());
+            await(runs, show);
+        } finally {
+            release.countDown();
+            runs.close();
+        }
+    }
+
+    public @Test void differentShowsRunConcurrentlyAndEditsRejectStaleResults() throws Exception {
+        final Show first = show();
+        final Show second = show();
+        final var entered = new CountDownLatch(2);
+        final var release = new CountDownLatch(1);
+        final var runs = new SchedulingRuns(schools, blocking(entered, release));
+        try {
+            runs.start(school, first.getId());
+            runs.start(school, second.getId());
+            assertTrue(entered.await(10, TimeUnit.SECONDS));
+            schools.touch(first);
+            release.countDown();
+            assertEquals(SchedulingState.STALE, await(runs, first).state());
+            assertTrue(first.getDayParts().getFirst().getDanceGroups().isEmpty());
+            assertEquals(SchedulingState.OPTIMAL, await(runs, second).state());
+        } finally {
+            release.countDown();
+            runs.close();
+        }
+    }
+
+    public @Test void failuresRemainVisibleAndReleaseTheShowForRetry() {
+        final Show show = show();
+        final List<SchedulingEngine> engines = new ArrayList<>();
+        engines.add((final SchedulingInput input) -> {
+            throw new IllegalStateException("failure");
+        });
+        engines.add((final SchedulingInput input) -> {
+            throw new UnsatisfiedLinkError("native");
+        });
+        engines.add((final SchedulingInput input) -> null);
+        for (final SchedulingFailureKind kind : SchedulingFailureKind.values()) {
+            engines.add((final SchedulingInput input) -> {
+                throw new SchedulingFailure(kind, "Explained outcome");
+            });
+        }
+        for (final SchedulingEngine engine : engines) {
+            assertFailure(show, engine);
+        }
+    }
+
+    private void assertFailure(final Show show, final SchedulingEngine engine) {
+        final var runs = new SchedulingRuns(schools, engine);
+        try {
+            runs.start(school, show.getId());
+            final SchedulingRun failed = await(runs, show);
+            assertNotEquals(SchedulingState.RUNNING, failed.state());
+            assertTrue(failed.message().contains("behouden"));
+            assertTrue(show.getDayParts().getFirst().getDanceGroups().isEmpty());
+            schools.endScheduling(schools.beginScheduling(school, show.getId()).showId());
+        } finally {
+            runs.close();
+        }
+    }
+
+    public @Test void validUnprovenResultIsAppliedAndShutdownRejectsNewWorkWithoutLeakingGuard() {
+        final Show show = show();
+        final SchedulingEngine engine = (final SchedulingInput input) -> new SchedulingResult(
+                false, new OrToolsSchedulingEngine().solve(input).assignments());
+        final var runs = new SchedulingRuns(schools, engine);
+        runs.start(school, show.getId());
+        assertEquals(SchedulingState.VALID, await(runs, show).state());
+        runs.close();
+        assertThrows(java.util.concurrent.RejectedExecutionException.class, () -> runs.start(school, show.getId()));
+        assertEquals(
+                SchedulingState.SOLVER_FAILED, runs.status(school, show.getId()).state());
+        schools.endScheduling(schools.beginScheduling(school, show.getId()).showId());
+    }
+
+    public @Test void databaseRecoveryPersistsPendingFailureWithoutRestart() throws Exception {
+        final Show show = show();
+        final var entered = new CountDownLatch(1);
+        final var release = new CountDownLatch(1);
+        final var persistence = new OutagePersistence();
+        final var runs = new SchedulingRuns(schools, blocking(entered, release));
+        final java.lang.reflect.Field field = SchedulingRuns.class.getDeclaredField("persistence");
+        field.setAccessible(true);
+        field.set(runs, persistence);
+        try {
+            final SchedulingRun started = runs.start(school, show.getId());
+            assertTrue(entered.await(10, TimeUnit.SECONDS));
+            persistence.available.set(false);
+            release.countDown();
+            assertTrue(persistence.unavailable.await(10, TimeUnit.SECONDS));
+            assertEquals(started, persistence.stored.get());
+            assertEquals(started, runs.status(school, show.getId()));
+            assertThrows(ManagementException.class, () -> runs.start(school, show.getId()));
+            persistence.available.set(true);
+            final SchedulingRun completed = await(runs, show);
+            assertEquals(SchedulingState.SOLVER_FAILED, completed.state());
+            assertEquals(started.runId(), completed.runId());
+            assertEquals(completed, persistence.stored.get());
+            schools.endScheduling(schools.beginScheduling(school, show.getId()).showId());
+        } finally {
+            persistence.available.set(true);
+            release.countDown();
+            runs.close();
+        }
+    }
+
+    private static class OutagePersistence extends SchedulingPersistence {
+        private final CountDownLatch unavailable = new CountDownLatch(2);
+        private final java.util.concurrent.atomic.AtomicBoolean available =
+                new java.util.concurrent.atomic.AtomicBoolean(true);
+        private final AtomicReference<SchedulingRun> stored = new AtomicReference<>();
+
+        private OutagePersistence() {
+            super(null, null, null);
+        }
+
+        public @Override <T> T work(final java.util.concurrent.Callable<T> action) {
+            if (!available.get()) {
+                unavailable.countDown();
+                throw new nl.agilecc.agiledancers.repository.StorageException(new IllegalStateException("offline"));
+            }
+            try {
+                return action.call();
+            } catch (final RuntimeException failure) {
+                throw failure;
+            } catch (final Exception failure) {
+                throw new IllegalStateException(failure);
+            }
+        }
+
+        public @Override void accepted(final SchedulingRun run, final Runnable launch, final Runnable rollback) {
+            save(run, launch);
+        }
+
+        public @Override void save(final SchedulingRun run, final Runnable publication) {
+            stored.set(run);
+            publication.run();
+        }
+    }
+
+    private Show show() {
+        final long group = schools.createGroup(
+                        school, new GroupDetails("Group", DanceGroupType.REGULAR, 0, 99, Set.of()))
+                .getId();
+        schools.addGroupDancer(
+                school,
+                group,
+                schools.createDancer(school, "Dancer", LocalDate.of(2000, 1, 1)).getId());
+        return schools.createShow(
+                school,
+                "Show",
+                List.of(DayPart.builder()
+                        .date(LocalDate.of(2027, 1, 1))
+                        .type(DayPartType.MORNING)
+                        .danceGroups(List.of())
+                        .build()),
+                null);
+    }
+
+    private SchedulingEngine blocking(final CountDownLatch entered, final CountDownLatch release) {
+        return (final SchedulingInput input) -> {
+            entered.countDown();
+            try {
+                assertTrue(release.await(10, TimeUnit.SECONDS));
+            } catch (final InterruptedException failure) {
+                Thread.currentThread().interrupt();
+                throw new IllegalStateException(failure);
+            }
+            // The real solver's callbacks are covered separately; exercise the default port overload here.
+            return new OrToolsSchedulingEngine().solve(input);
+        };
+    }
+
+    private SchedulingRun await(final SchedulingRuns runs, final Show show) {
+        final long deadline = System.nanoTime() + TimeUnit.SECONDS.toNanos(10);
+        SchedulingRun status = runs.status(school, show.getId());
+        while (status.state().equals(SchedulingState.RUNNING) && System.nanoTime() < deadline) {
+            LockSupport.parkNanos(TimeUnit.MILLISECONDS.toNanos(10));
+            status = runs.status(school, show.getId());
+        }
+        assertNotEquals(SchedulingState.RUNNING, status.state());
+        return status;
+    }
+}

agiledancers-fe/e2e/school-management.spec.ts

@@ -1,4 +1,4 @@
-import { test, expect, Page } from '@playwright/test';
+import { test, expect, Page, APIRequestContext } from '@playwright/test';
 import type { School } from '../src/app/core/api-models';
 
 const backend = process.env['PLAYWRIGHT_BASE_URL'] || 'http://127.0.0.1:8080';
@@ -6,11 +6,23 @@ let schoolToDelete: number | undefined;
 
 test.afterEach(async ({ request }) => {
   if (schoolToDelete !== undefined) {
-    await request.delete(`${backend}/api/dance-schools/${schoolToDelete}`);
+    await request.delete(`${backend}/api/dance-schools/${schoolToDelete}`, {
+      headers: await revision(request, schoolToDelete),
+    });
     schoolToDelete = undefined;
   }
 });
 
+async function revision(
+  request: APIRequestContext,
+  schoolId: number,
+): Promise<Record<string, string>> {
+  const school = (await (
+    await request.get(`${backend}/api/dance-schools/${schoolId}`)
+  ).json()) as School;
+  return { 'X-School-Revision': String(school.revision) };
+}
+
 async function tab(page: Page, label: string) {
   await page
     .getByRole('navigation', { name: 'Dansschool onderdelen' })
@@ -113,6 +125,7 @@ test('manages a school, shared memberships and shows through the real REST API',
     const dancerResponse = await request.post(
       `${backend}/api/dance-schools/${schoolToDelete}/dancers`,
       {
+        headers: await revision(request, schoolToDelete),
         data: { name, birthDate: '1990-01-01' },
       },
     );
@@ -120,14 +133,17 @@ test('manages a school, shared memberships and shows through the real REST API',
     const groupResponse = await request.post(
       `${backend}/api/dance-schools/${schoolToDelete}/dance-groups`,
       {
+        headers: await revision(request, schoolToDelete),
         data: { category: name, type: 'REGULAR', startAge: 0, endAge: 99, styles: ['MODERN'] },
       },
     );
     const group = (await groupResponse.json()) as { id: number };
     await request.put(
       `${backend}/api/dance-schools/${schoolToDelete}/dance-groups/${group.id}/dancers/${dancer.id}`,
+      { headers: await revision(request, schoolToDelete) },
     );
   }
+  await page.reload();
   await tab(page, 'Shows');
   await page.getByRole('button', { name: 'Show toevoegen' }).click();
   await page.getByRole('dialog').getByLabel('Naam', { exact: true }).fill('Zomershow');
@@ -143,8 +159,13 @@ test('manages a school, shared memberships and shows through the real REST API',
   await page.getByRole('button', { name: /Schedule groups/ }).click();
   await expect(page.getByText('Planning voldoet aan alle harde regels.')).toBeVisible();
   await expect(
-    page.getByRole('status').filter({ hasText: 'Optimaal conceptrooster.' }),
+    page.locator('.scheduling-progress').filter({ hasText: 'Optimaal conceptrooster.' }),
   ).toBeVisible();
+  await expect(page.locator('.scheduling-snackbar')).toContainText('Zomershow');
+  await expect(page.locator('.scheduling-progress')).toContainText('Spreiding:');
+  await page.reload();
+  await expect(page.locator('.scheduling-progress')).toContainText('Optimaal conceptrooster.');
+  await expect(page.locator('.scheduling-snackbar')).toHaveCount(0);
   await page.getByRole('button', { name: 'Indeling en volgorde bewerken' }).click();
   const scheduleDialog = page.getByRole('dialog');
   await scheduleDialog.getByRole('button', { name: 'Definitief maken' }).click();
@@ -209,12 +230,14 @@ test('links a coach and finalizes performances spread across multiple dates', as
   schoolToDelete = school.id;
   const base = `${backend}/api/dance-schools/${school.id}`;
   const dancerResponse = await request.post(`${base}/dancers`, {
+    headers: await revision(request, school.id),
     data: { name: 'Dancing coach', birthDate: '1990-01-01' },
   });
   const dancer = (await dancerResponse.json()) as { id: number };
   const groupIds: number[] = [];
   for (const name of ['Preschool', 'Adults']) {
     const response = await request.post(`${base}/dance-groups`, {
+      headers: await revision(request, school.id),
       data: {
         category: name,
         type: name === 'Preschool' ? 'PRE_SCHOOLER' : 'REGULAR',
@@ -225,9 +248,12 @@ test('links a coach and finalizes performances spread across multiple dates', as
     });
     const group = (await response.json()) as { id: number };
     groupIds.push(group.id);
-    await request.put(`${base}/dance-groups/${group.id}/dancers/${dancer.id}`);
+    await request.put(`${base}/dance-groups/${group.id}/dancers/${dancer.id}`, {
+      headers: await revision(request, school.id),
+    });
   }
   const showResponse = await request.post(`${base}/shows`, {
+    headers: await revision(request, school.id),
     data: {
       name: 'Coach across dates',
       preferredDayParts: 1,
@@ -239,6 +265,7 @@ test('links a coach and finalizes performances spread across multiple dates', as
   });
   const show = (await showResponse.json()) as { id: number };
   await request.put(`${base}/shows/${show.id}/assignments`, {
+    headers: await revision(request, school.id),
     data: { assignments: groupIds.map((id) => [id]) },
   });
   await page.goto(`/schools/${school.id}/shows`);
@@ -266,3 +293,39 @@ test('shows a useful connection error and recovers on retry', async ({ page }) =
   await page.getByRole('button', { name: 'Opnieuw proberen' }).click();
   await expect(page.getByRole('heading', { name: /Mijn dansscholen/ })).toBeVisible();
 });
+
+test('rejects a stale editor in another screen and allows reload and retry', async ({
+  page,
+  request,
+}) => {
+  const response = await request.post(`${backend}/api/dance-schools`, {
+    data: { name: `Concurrent school ${Date.now()}` },
+  });
+  const school = (await response.json()) as School;
+  schoolToDelete = school.id;
+  const other = await page.context().newPage();
+  try {
+    for (const screen of [page, other]) {
+      await screen.goto(`/schools/${school.id}/overview`);
+      await screen.getByRole('button', { name: 'School bewerken' }).click();
+    }
+    await page.getByRole('dialog').getByLabel('Naam', { exact: true }).fill('First confirmed edit');
+    await other.getByRole('dialog').getByLabel('Naam', { exact: true }).fill('Stale edit');
+    await save(page);
+    await other.getByRole('dialog').getByRole('button', { name: 'Opslaan', exact: true }).click();
+    await expect(other.getByRole('dialog').getByRole('alert')).toContainText('Herlaad');
+    await expect(other.getByRole('dialog').getByLabel('Naam', { exact: true })).toHaveValue(
+      'Stale edit',
+    );
+    await other.reload();
+    await expect(
+      other.getByRole('heading', { name: 'First confirmed edit', exact: true }),
+    ).toBeVisible();
+    await other.getByRole('button', { name: 'School bewerken' }).click();
+    await other.getByRole('dialog').getByLabel('Naam', { exact: true }).fill('Reloaded edit');
+    await save(other);
+    await expect(other.getByRole('heading', { name: 'Reloaded edit', exact: true })).toBeVisible();
+  } finally {
+    await other.close();
+  }
+});

agiledancers-fe/nginx/default.conf.template

@@ -5,6 +5,10 @@ server {
     index index.html;
 
     location /api/ {
+        proxy_buffering off;
+        proxy_cache off;
+        proxy_http_version 1.1;
+        proxy_set_header Connection "";
         proxy_read_timeout 1860s;
         proxy_send_timeout 1860s;
         proxy_pass http://${BACKEND_UPSTREAM};

agiledancers-fe/src/app/app.config.ts

@@ -11,7 +11,10 @@ export const appConfig: ApplicationConfig = {
   providers: [
     provideBrowserGlobalErrorListeners(),
     provideHttpClient(),
-    provideRouter(routes, withInMemoryScrolling({ scrollPositionRestoration: 'enabled' })),
+    provideRouter(
+      routes,
+      withInMemoryScrolling({ scrollPositionRestoration: 'enabled', anchorScrolling: 'enabled' }),
+    ),
     { provide: LOCALE_ID, useValue: 'nl-NL' },
   ],
 };

agiledancers-fe/src/app/app.css

@@ -237,3 +237,30 @@ main {
     margin: 0 20px;
   }
 }
+
+.scheduling-snackbar {
+  position: fixed;
+  bottom: 1.5rem;
+  right: 1.5rem;
+  z-index: 1000;
+  display: flex;
+  align-items: center;
+  gap: 1rem;
+  max-width: min(40rem, calc(100vw - 3rem));
+  padding: 1rem 1.5rem;
+  background: #193b33;
+  color: white;
+  border-radius: 0.75rem;
+  box-shadow: 0 0.25rem 1rem #0003;
+}
+.scheduling-snackbar a {
+  color: white;
+  text-decoration: underline;
+}
+.scheduling-snackbar button {
+  background: transparent;
+  color: white;
+  border: 0;
+  cursor: pointer;
+  font-size: 1.5rem;
+}

agiledancers-fe/src/app/app.html

@@ -44,3 +44,19 @@
     </footer>
   </div>
 </div>
+
+@if (scheduling.notifications()[0]; as run) {
+  <aside class="scheduling-snackbar" role="status" aria-live="polite">
+    <span
+      ><strong>{{ run.showName }}</strong
+      >: {{ run.message }}</span
+    >
+    <a
+      [routerLink]="['/schools', run.schoolId, 'shows']"
+      [fragment]="'show-' + run.showId"
+      (click)="scheduling.dismiss()"
+      >Bekijk show</a
+    >
+    <button type="button" aria-label="Melding sluiten" (click)="scheduling.dismiss()">×</button>
+  </aside>
+}

agiledancers-fe/src/app/app.spec.ts

@@ -1,12 +1,17 @@
 import { TestBed } from '@angular/core/testing';
 import { provideRouter } from '@angular/router';
 import { App } from './app';
+import { SchedulingStatus } from './core/scheduling-status';
+import { signal } from '@angular/core';
 
 describe('Application shell', () => {
   it('provides navigation and a keyboard skip link', async () => {
     await TestBed.configureTestingModule({
       imports: [App],
-      providers: [provideRouter([])],
+      providers: [
+        provideRouter([]),
+        { provide: SchedulingStatus, useValue: { connect: vi.fn(), notifications: signal([]) } },
+      ],
     }).compileComponents();
     const fixture = TestBed.createComponent(App);
     await fixture.whenStable();

agiledancers-fe/src/app/app.ts

@@ -1,4 +1,5 @@
-import { Component } from '@angular/core';
+import { SchedulingStatus } from './core/scheduling-status';
+import { Component, inject, OnInit } from '@angular/core';
 import { RouterLink, RouterOutlet } from '@angular/router';
 
 @Component({
@@ -7,4 +8,10 @@ import { RouterLink, RouterOutlet } from '@angular/router';
   templateUrl: './app.html',
   styleUrl: './app.css',
 })
-export class App {}
+export class App implements OnInit {
+  readonly scheduling = inject(SchedulingStatus);
+
+  ngOnInit(): void {
+    this.scheduling.connect();
+  }
+}

agiledancers-fe/src/app/core/api-models.ts

@@ -1,5 +1,6 @@
 export interface School {
   id: number;
+  revision: number;
   name: string;
   dancerIds: number[];
   danceGroupIds: number[];

agiledancers-fe/src/app/core/scheduling-status.spec.ts

@@ -0,0 +1,108 @@
+import { TestBed } from '@angular/core/testing';
+import { SchedulingRun, SchedulingState, SchedulingStatus } from './scheduling-status';
+
+class FakeEventSource {
+  static current: FakeEventSource;
+  readonly close = vi.fn();
+  onmessage?: (event: { data: string }) => void;
+  onerror?: () => void;
+  constructor(readonly url: string) {
+    FakeEventSource.current = this;
+  }
+  send(runs: SchedulingRun[] | null): void {
+    this.onmessage?.({ data: JSON.stringify({ runs }) });
+  }
+}
+
+function run(state: SchedulingState, runId = 'run-1'): SchedulingRun {
+  return {
+    runId,
+    schoolId: 1,
+    showId: 2,
+    showName: 'Zomershow',
+    startedAt: '2026-11-03T12:00:00Z',
+    finishedAt: state === 'RUNNING' ? null : '2026-11-03T12:01:02Z',
+    state,
+    progress: { phase: 'VARIETY', feasible: true },
+    message: 'Afgerond',
+    summary: null,
+  };
+}
+
+describe('Scheduling status over SSE', () => {
+  let status: SchedulingStatus;
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.stubGlobal('EventSource', FakeEventSource);
+    TestBed.configureTestingModule({});
+    status = TestBed.inject(SchedulingStatus);
+    status.connect();
+  });
+  afterEach(() => {
+    TestBed.resetTestingModule();
+    vi.unstubAllGlobals();
+    vi.useRealTimers();
+  });
+
+  it('recovers an existing outcome without replaying old notifications', () => {
+    expect(FakeEventSource.current.url).toBe('/api/scheduling/events');
+    FakeEventSource.current.send([run('OPTIMAL')]);
+    expect(status.run(1, 2)?.state).toBe('OPTIMAL');
+    expect(status.notifications()).toEqual([]);
+    expect(status.elapsed(run('OPTIMAL'))).toBe('1m 2s');
+    expect(status.phase(run('OPTIMAL'))).toBe('Variatie');
+  });
+
+  it('announces a completion missed during disconnection exactly once', () => {
+    FakeEventSource.current.send([run('RUNNING')]);
+    FakeEventSource.current.onerror?.();
+    expect(status.connected()).toBe(false);
+    const disconnected = FakeEventSource.current;
+    vi.advanceTimersByTime(3000);
+    expect(FakeEventSource.current).not.toBe(disconnected);
+    expect(disconnected.close).toHaveBeenCalledOnce();
+    expect(status.run(1, 2)?.state).toBe('RUNNING');
+    FakeEventSource.current.send([run('VALID')]);
+    expect(status.connected()).toBe(true);
+    expect(status.notifications()).toHaveLength(1);
+    status.dismiss();
+    FakeEventSource.current.send([run('VALID')]);
+    expect(status.notifications()).toEqual([]);
+  });
+
+  it('does not treat heartbeats or phase changes as completions', () => {
+    FakeEventSource.current.send(null);
+    FakeEventSource.current.send([run('OPTIMAL')]);
+    expect(status.notifications()).toEqual([]);
+    FakeEventSource.current.send([run('RUNNING', 'run-2')]);
+    FakeEventSource.current.send(null);
+    expect(status.run(1, 2)?.runId).toBe('run-2');
+    expect(status.notifications()).toEqual([]);
+    FakeEventSource.current.send([run('SOLVER_FAILED', 'run-2')]);
+    expect(status.notifications()).toHaveLength(1);
+  });
+
+  it('announces a locally started run completed before the first SSE snapshot', () => {
+    FakeEventSource.current.onerror?.();
+    status.started(run('RUNNING'));
+    vi.advanceTimersByTime(3000);
+    FakeEventSource.current.send([run('OPTIMAL'), run('VALID', 'historical')]);
+    expect(status.notifications().map((item) => item.runId)).toEqual(['run-1']);
+    status.dismiss();
+    FakeEventSource.current.onerror?.();
+    vi.advanceTimersByTime(3000);
+    FakeEventSource.current.send([run('OPTIMAL'), run('VALID', 'historical')]);
+    expect(status.notifications()).toEqual([]);
+  });
+
+  it('retains a fast completion when the start response arrives after SSE', () => {
+    FakeEventSource.current.send([]);
+    FakeEventSource.current.send([run('OPTIMAL')]);
+    status.started(run('RUNNING'));
+    expect(status.run(1, 2)?.state).toBe('OPTIMAL');
+    status.connect();
+    const source = FakeEventSource.current;
+    TestBed.resetTestingModule();
+    expect(source.close).toHaveBeenCalledOnce();
+  });
+});

agiledancers-fe/src/app/core/scheduling-status.ts

@@ -0,0 +1,125 @@
+import { DestroyRef, inject, Injectable, signal } from '@angular/core';
+
+export type SchedulingState =
+  | 'RUNNING'
+  | 'INTERRUPTED'
+  | 'OPTIMAL'
+  | 'VALID'
+  | 'STALE'
+  | 'INVALID_INPUT'
+  | 'INFEASIBLE'
+  | 'NO_SOLUTION'
+  | 'SOLVER_FAILED';
+export type SchedulingPhase = 'PREPARING' | 'ATTENDANCE' | 'SPREAD' | 'VARIETY';
+
+export interface SchedulingRun {
+  runId: string;
+  schoolId: number;
+  showId: number;
+  showName: string;
+  startedAt: string;
+  finishedAt: string | null;
+  state: SchedulingState;
+  progress: { phase: SchedulingPhase; feasible: boolean };
+  message: string;
+  summary: {
+    attendanceExcess: number;
+    performanceSpread: number;
+    varietyPenalty: number;
+  } | null;
+}
+
+@Injectable({ providedIn: 'root' })
+export class SchedulingStatus {
+  private readonly destroyRef = inject(DestroyRef);
+  readonly runs = signal<SchedulingRun[]>([]);
+  readonly connected = signal(false);
+  readonly notifications = signal<SchedulingRun[]>([]);
+  readonly now = signal(Date.now());
+  private source?: EventSource;
+  private reconnectTimer?: ReturnType<typeof setTimeout>;
+  private initialized = false;
+  private readonly seen = new Set<string>();
+
+  connect(): void {
+    if (this.source) return;
+    this.open();
+    const timer = setInterval(() => this.now.set(Date.now()), 1000);
+    this.destroyRef.onDestroy(() => {
+      this.source?.close();
+      clearTimeout(this.reconnectTimer);
+      clearInterval(timer);
+    });
+  }
+
+  private open(): void {
+    const source = new EventSource('/api/scheduling/events');
+    this.source = source;
+    source.onmessage = (event: MessageEvent<string>) => {
+      const eventData = JSON.parse(event.data) as { runs: SchedulingRun[] | null };
+      if (eventData.runs !== null) this.accept(eventData.runs);
+      this.connected.set(true);
+    };
+    source.onerror = () => {
+      this.connected.set(false);
+      // Retry also when a proxy error makes native EventSource reconnection stop permanently.
+      source.close();
+      clearTimeout(this.reconnectTimer);
+      this.reconnectTimer = setTimeout(() => this.open(), 3000);
+    };
+  }
+
+  private accept(runs: SchedulingRun[]): void {
+    const activeRuns = new Set(
+      this.runs()
+        .filter((run) => run.state === 'RUNNING')
+        .map((run) => run.runId),
+    );
+    for (const run of runs) {
+      if (run.state === 'RUNNING' || this.seen.has(run.runId)) continue;
+      this.seen.add(run.runId);
+      if (this.initialized || activeRuns.has(run.runId))
+        this.notifications.update((items) => [...items, run]);
+    }
+    this.initialized = true;
+    this.runs.set(runs);
+  }
+
+  run(schoolId: number, showId: number): SchedulingRun | undefined {
+    return this.runs().find((run) => run.schoolId === schoolId && run.showId === showId);
+  }
+
+  started(run: SchedulingRun): void {
+    // The SSE completion can arrive before the POST response. Never overwrite it with RUNNING.
+    if (this.runs().some((item) => item.runId === run.runId)) return;
+    this.runs.update((items) => [...items.filter((item) => item.showId !== run.showId), run]);
+  }
+
+  elapsed(run: SchedulingRun): string {
+    const seconds = Math.max(
+      0,
+      Math.floor(
+        ((run.finishedAt ? Date.parse(run.finishedAt) : this.now()) - Date.parse(run.startedAt)) /
+          1000,
+      ),
+    );
+    return `${Math.floor(seconds / 60)}m ${seconds % 60}s`;
+  }
+
+  phase(run: SchedulingRun): string {
+    return (
+      (
+        {
+          PREPARING: 'Voorbereiden',
+          ATTENDANCE: 'Aanwezigheid',
+          SPREAD: 'Spreiding',
+          VARIETY: 'Variatie',
+        } satisfies Record<SchedulingPhase, string>
+      )[run.progress.phase] ?? run.progress.phase
+    );
+  }
+
+  dismiss(): void {
+    this.notifications.update((items) => items.slice(1));
+  }
+}

agiledancers-fe/src/app/core/school-api.spec.ts

@@ -18,13 +18,17 @@ describe('SchoolApi contract', () => {
   it('loads all resources from the same school', () => {
     const received = vi.fn();
     api.schoolData(7).subscribe(received);
-    const school = { id: 7, name: 'Studio', dancerIds: [], danceGroupIds: [], showIds: [] };
-    http.expectOne('/api/dance-schools/7').flush(school);
-    http.expectOne('/api/dance-schools/7/dancers').flush([]);
-    http.expectOne('/api/dance-schools/7/dance-groups').flush([]);
-    expect(received).not.toHaveBeenCalled();
-    http.expectOne('/api/dance-schools/7/shows').flush([]);
-    http.expectOne('/api/dance-schools/7/coaches').flush([]);
+    const school = {
+      id: 7,
+      name: 'Studio',
+      revision: 0,
+      dancerIds: [],
+      danceGroupIds: [],
+      showIds: [],
+    };
+    http
+      .expectOne('/api/dance-schools/7/data')
+      .flush({ school, dancers: [], groups: [], shows: [], coaches: [] });
     expect(received).toHaveBeenCalledWith({
       school,
       dancers: [],
@@ -34,12 +38,32 @@ describe('SchoolApi contract', () => {
     });
   });
 
+  it('sends the loaded school revision without retrying a stale mutation', () => {
+    api.schoolData(7).subscribe();
+    http
+      .expectOne('/api/dance-schools/7/data')
+      .flush({ school: { id: 7, revision: 4 }, dancers: [], groups: [], shows: [], coaches: [] });
+    const failure = vi.fn();
+    api.saveDancer(7, { name: 'Sam', birthDate: '2010-05-12' }).subscribe({ error: failure });
+    const request = http.expectOne('/api/dance-schools/7/dancers');
+    expect(request.request.headers.get('X-School-Revision')).toBe('4');
+    request.flush({ message: 'Herlaad de gegevens' }, { status: 409, statusText: 'Conflict' });
+    expect(failure).toHaveBeenCalledOnce();
+  });
+
   it('updates an existing entity even when its id is zero', () => {
     api.saveSchool({ name: 'Renamed' }, 0).subscribe();
     const request = http.expectOne('/api/dance-schools/0');
     expect(request.request.method).toBe('PUT');
     expect(request.request.body).toEqual({ name: 'Renamed' });
-    request.flush({ id: 0, name: 'Renamed', dancerIds: [], danceGroupIds: [], showIds: [] });
+    request.flush({
+      id: 0,
+      name: 'Renamed',
+      revision: 0,
+      dancerIds: [],
+      danceGroupIds: [],
+      showIds: [],
+    });
   });
 
   it('keeps group details separate from memberships', () => {
@@ -73,11 +97,11 @@ describe('SchoolApi contract', () => {
       .flush({ message: 'Invalid data' }, { status: 400, statusText: 'Bad Request' });
     expect(failure).toHaveBeenCalledOnce();
   });
-  it('schedules synchronously with room for the 30-minute solver limit', () => {
+  it('starts a background calculation without a solver-length HTTP timeout', () => {
     api.schedule(7, 3).subscribe();
     const request = http.expectOne('/api/dance-schools/7/shows/3/schedule');
     expect(request.request.method).toBe('POST');
-    expect(request.request.timeout).toBe(1860000);
+    expect(request.request.timeout).toBeUndefined();
     request.flush({ optimal: false, message: 'Valid result; optimal balance not proven' });
   });
 });

agiledancers-fe/src/app/core/school-api.ts

@@ -1,6 +1,7 @@
+import { SchedulingRun } from './scheduling-status';
 import { inject, Injectable } from '@angular/core';
 import { HttpClient } from '@angular/common/http';
-import { forkJoin, Observable } from 'rxjs';
+import { Observable, tap } from 'rxjs';
 import {
   Coach,
   DanceGroup,
@@ -19,68 +20,114 @@ import {
 export class SchoolApi {
   private readonly http = inject(HttpClient);
   private readonly base = '/api/dance-schools';
+  private readonly revisions = new Map<number, number>();
 
   schools(): Observable<School[]> {
-    return this.http.get<School[]>(this.base);
-  }
-  schoolData(schoolId: number): Observable<SchoolData> {
-    const base = `${this.base}/${schoolId}`;
-    return forkJoin({
-      school: this.http.get<School>(base),
-      dancers: this.http.get<Dancer[]>(`${base}/dancers`),
-      groups: this.http.get<DanceGroup[]>(`${base}/dance-groups`),
-      shows: this.http.get<Show[]>(`${base}/shows`),
-      coaches: this.http.get<Coach[]>(`${base}/coaches`),
-    });
-  }
-  saveSchool(body: SchoolRequest, id?: number): Observable<School> {
-    return id === undefined
-      ? this.http.post<School>(this.base, body)
-      : this.http.put<School>(`${this.base}/${id}`, body);
-  }
-  saveDancer(schoolId: number, body: DancerRequest, id?: number): Observable<Dancer> {
-    return this.save(`${this.base}/${schoolId}/dancers`, body, id);
-  }
-  saveGroup(schoolId: number, body: GroupRequest, id?: number): Observable<DanceGroup> {
-    return this.save(`${this.base}/${schoolId}/dance-groups`, body, id);
-  }
-  saveShow(schoolId: number, body: ShowRequest, id?: number): Observable<Show> {
-    return this.save(`${this.base}/${schoolId}/shows`, body, id);
-  }
-  schedule(schoolId: number, showId: number): Observable<{ optimal: boolean; message: string }> {
-    return this.http.post<{ optimal: boolean; message: string }>(
-      `${this.base}/${schoolId}/shows/${showId}/schedule`,
-      null,
-      { timeout: 1860000 },
+    return this.http.get<School[]>(this.base).pipe(
+      tap((schools) => {
+        for (const school of schools) this.revisions.set(school.id, school.revision);
+      }),
     );
   }
-  saveAssignments(schoolId: number, showId: number, assignments: number[][]): Observable<Show> {
-    return this.http.put<Show>(`${this.base}/${schoolId}/shows/${showId}/assignments`, {
-      assignments,
-    });
+  schoolData(schoolId: number): Observable<SchoolData> {
+    return this.http
+      .get<SchoolData>(`${this.base}/${schoolId}/data`)
+      .pipe(tap((data) => this.revisions.set(schoolId, data.school.revision)));
   }
-  finalize(schoolId: number, showId: number): Observable<Show> {
-    return this.http.post<Show>(`${this.base}/${schoolId}/shows/${showId}/finalize`, null);
+  private options(schoolId: number, expected?: number): { headers: Record<string, string> } {
+    const revision = expected ?? this.revisions.get(schoolId);
+    return { headers: revision === undefined ? {} : { 'X-School-Revision': String(revision) } };
+  }
+  saveSchool(body: SchoolRequest, id?: number, revision?: number): Observable<School> {
+    return id === undefined
+      ? this.http.post<School>(this.base, body)
+      : this.http.put<School>(`${this.base}/${id}`, body, this.options(id, revision));
+  }
+  saveDancer(
+    schoolId: number,
+    body: DancerRequest,
+    id?: number,
+    revision?: number,
+  ): Observable<Dancer> {
+    return this.save(`${this.base}/${schoolId}/dancers`, body, schoolId, id, revision);
+  }
+  saveGroup(
+    schoolId: number,
+    body: GroupRequest,
+    id?: number,
+    revision?: number,
+  ): Observable<DanceGroup> {
+    return this.save(`${this.base}/${schoolId}/dance-groups`, body, schoolId, id, revision);
+  }
+  saveShow(schoolId: number, body: ShowRequest, id?: number, revision?: number): Observable<Show> {
+    return this.save(`${this.base}/${schoolId}/shows`, body, schoolId, id, revision);
+  }
+  schedule(schoolId: number, showId: number): Observable<SchedulingRun> {
+    return this.http.post<SchedulingRun>(
+      `${this.base}/${schoolId}/shows/${showId}/schedule`,
+      null,
+      this.options(schoolId),
+    );
+  }
+  saveAssignments(
+    schoolId: number,
+    showId: number,
+    assignments: number[][],
+    revision?: number,
+  ): Observable<Show> {
+    return this.http.put<Show>(
+      `${this.base}/${schoolId}/shows/${showId}/assignments`,
+      {
+        assignments,
+      },
+      this.options(schoolId, revision),
+    );
+  }
+  finalize(schoolId: number, showId: number, revision?: number): Observable<Show> {
+    return this.http.post<Show>(
+      `${this.base}/${schoolId}/shows/${showId}/finalize`,
+      null,
+      this.options(schoolId, revision),
+    );
   }
   linkCoach(schoolId: number, dancerId: number, coachId?: number): Observable<Coach> {
-    return this.save<Coach>(`${this.base}/${schoolId}/coaches`, { dancerId }, coachId);
+    return this.save<Coach>(`${this.base}/${schoolId}/coaches`, { dancerId }, schoolId, coachId);
   }
   unlinkCoach(schoolId: number, coachId: number): Observable<void> {
-    return this.http.delete<void>(`${this.base}/${schoolId}/coaches/${coachId}/dancer`);
+    return this.http.delete<void>(
+      `${this.base}/${schoolId}/coaches/${coachId}/dancer`,
+      this.options(schoolId),
+    );
   }
-  delete(kind: ResourceKind, schoolId: number, id: number): Observable<void> {
+  delete(kind: ResourceKind, schoolId: number, id: number, revision?: number): Observable<void> {
     const collection = { school: '', dancer: '/dancers', group: '/dance-groups', show: '/shows' }[
       kind
     ];
     const url =
       kind === 'school' ? `${this.base}/${id}` : `${this.base}/${schoolId}${collection}/${id}`;
-    return this.http.delete<void>(url);
+    return this.http.delete<void>(url, this.options(schoolId, revision));
   }
-  membership(schoolId: number, groupId: number, dancerId: number, add: boolean): Observable<void> {
+  membership(
+    schoolId: number,
+    groupId: number,
+    dancerId: number,
+    add: boolean,
+    revision?: number,
+  ): Observable<void> {
     const url = `${this.base}/${schoolId}/dance-groups/${groupId}/dancers/${dancerId}`;
-    return add ? this.http.put<void>(url, null) : this.http.delete<void>(url);
+    return add
+      ? this.http.put<void>(url, null, this.options(schoolId, revision))
+      : this.http.delete<void>(url, this.options(schoolId, revision));
   }
-  private save<T>(url: string, body: unknown, id?: number): Observable<T> {
-    return id === undefined ? this.http.post<T>(url, body) : this.http.put<T>(`${url}/${id}`, body);
+  private save<T>(
+    url: string,
+    body: unknown,
+    schoolId: number,
+    id?: number,
+    revision?: number,
+  ): Observable<T> {
+    return id === undefined
+      ? this.http.post<T>(url, body, this.options(schoolId, revision))
+      : this.http.put<T>(`${url}/${id}`, body, this.options(schoolId, revision));
   }
 }

agiledancers-fe/src/app/schools/school-page.html

@@ -344,7 +344,7 @@
       </div>
       <div class="show-list">
         @for (show of shows(); track show.id) {
-          <article class="show-card">
+          <article class="show-card" [id]="'show-' + show.id">
             <div class="date-tile">
               <strong>{{ firstDate(show) | date: 'dd' }}</strong
               ><span>{{ firstDate(show) | date: 'MMM yyyy' }}</span>
@@ -372,6 +372,48 @@
                     : 'Geen geldige planning. Plan de groepen opnieuw in.'
                 }}
               </p>
+              @if (schedulingStatus.run(context.school.id, show.id); as run) {
+                <div class="scheduling-progress" role="status">
+                  @if (!schedulingStatus.connected()) {
+                    <p>
+                      Verbinding verbroken. Status mogelijk verouderd; de berekening loopt door.
+                    </p>
+                  }
+                  @if (run.state === 'RUNNING') {
+                    <p>
+                      Bezig met inplannen · {{ schedulingStatus.phase(run) }} ·
+                      {{ schedulingStatus.elapsed(run) }}
+                    </p>
+                    <p>
+                      {{
+                        run.progress.feasible
+                          ? 'Geldige oplossing gevonden; optimalisatie loopt door.'
+                          : 'Nog geen geldige oplossing gevonden.'
+                      }}
+                    </p>
+                  } @else {
+                    <p>{{ run.message }}</p>
+                    <p>
+                      Afgerond: {{ run.finishedAt | date: 'dd-MM-yyyy HH:mm:ss' }} · Duur:
+                      {{ schedulingStatus.elapsed(run) }}
+                    </p>
+                    @if (run.summary; as summary) {
+                      <p>
+                        Aanwezigheid: {{ summary.attendanceExcess }} extra dagdelen boven voorkeur
+                        (showcasedansers, exclusief coaches).
+                      </p>
+                      <p>
+                        Spreiding: {{ summary.performanceSpread }} optredens verschil tussen drukste
+                        en rustigste dagdeel.
+                      </p>
+                      <p>
+                        Variatie: {{ summary.varietyPenalty }} strafpunten voor opeenvolgende
+                        groepen (lager is beter).
+                      </p>
+                    }
+                  }
+                </div>
+              }
               <button
                 type="button"
                 class="button primary"
@@ -435,6 +477,7 @@
     <app-entity-editor
       [target]="target"
       [schoolId]="context.school.id"
+      [revision]="context.school.revision"
       [shows]="context.shows"
       (closed)="editor.set(null)"
       (saved)="saved()"
@@ -445,6 +488,7 @@
       [show]="show"
       [groups]="context.groups"
       [schoolId]="context.school.id"
+      [revision]="context.school.revision"
       (closed)="scheduleEditing.set(null)"
       (saved)="reload()"
     />
@@ -453,6 +497,7 @@
     <app-group-members
       [group]="group"
       [schoolId]="context.school.id"
+      [revision]="context.school.revision"
       [dancers]="context.dancers"
       (closed)="members.set(null)"
       (changed)="membershipChanged($event)"

agiledancers-fe/src/app/schools/school-page.ts

@@ -1,5 +1,5 @@
 import { SchoolTransfer } from '../shared/school-transfer';
-import { Component, computed, DestroyRef, inject, OnInit, signal } from '@angular/core';
+import { Component, computed, DestroyRef, effect, inject, OnInit, signal } from '@angular/core';
 import { DatePipe } from '@angular/common';
 import { takeUntilDestroyed } from '@angular/core/rxjs-interop';
 import { ActivatedRoute, Router, RouterLink, RouterLinkActive } from '@angular/router';
@@ -14,6 +14,7 @@ import {
   Show,
 } from '../core/api-models';
 import { apiError } from '../core/api-error';
+import { SchedulingStatus } from '../core/scheduling-status';
 import { SchoolApi } from '../core/school-api';
 import { EntityEditor } from '../shared/entity-editor';
 import { ConfirmDialog } from '../shared/confirm-dialog';
@@ -57,7 +58,30 @@ export class SchoolPage implements OnInit {
   readonly scheduleEditing = signal<Show | null>(null);
   readonly members = signal<DanceGroup | null>(null);
   readonly deleting = signal<DeleteTarget | null>(null);
-  readonly scheduling = signal<number[]>([]);
+  readonly schedulingStatus = inject(SchedulingStatus);
+  private readonly starting = signal<number[]>([]);
+  readonly scheduling = computed(() => [
+    ...this.starting(),
+    ...this.schedulingStatus
+      .runs()
+      .filter((run) => run.schoolId === this.data()?.school.id && run.state === 'RUNNING')
+      .map((run) => run.showId),
+  ]);
+  private readonly completed = new Set<string>();
+
+  constructor() {
+    effect(() => {
+      const schoolId = this.data()?.school.id;
+      let changed = false;
+      for (const run of this.schedulingStatus.runs()) {
+        if (run.schoolId !== schoolId || run.state === 'RUNNING' || this.completed.has(run.runId))
+          continue;
+        this.completed.add(run.runId);
+        changed = true;
+      }
+      if (changed) void this.reload();
+    });
+  }
   readonly deleteBusy = signal(false);
   readonly deleteError = signal('');
   readonly search = signal('');
@@ -151,20 +175,15 @@ export class SchoolPage implements OnInit {
       )
     )
       return;
-    this.scheduling.update((ids) => [...ids, show.id]);
+    this.starting.update((ids) => [...ids, show.id]);
     this.error.set('');
     try {
       const result = await firstValueFrom(this.api.schedule(schoolId, show.id));
-      this.notice.set(
-        result.optimal
-          ? 'Optimaal conceptrooster.'
-          : 'Geldig conceptrooster; optimaliteit niet bewezen.',
-      );
-      await this.reload();
+      this.schedulingStatus.started(result);
     } catch (error: unknown) {
       this.error.set(apiError(error));
     } finally {
-      this.scheduling.update((ids) => ids.filter((id) => id !== show.id));
+      this.starting.update((ids) => ids.filter((id) => id !== show.id));
     }
   }
   async reload(): Promise<void> {
@@ -200,7 +219,10 @@ export class SchoolPage implements OnInit {
         .join(', ') || 'Nog geen groep'
     );
   }
+  private deletionRevision?: number;
+
   askDelete(target: DeleteTarget): void {
+    this.deletionRevision = this.data()?.school.revision;
     this.deleteError.set('');
     if (target.kind === 'group') {
       const names =
@@ -236,7 +258,9 @@ export class SchoolPage implements OnInit {
     this.deleteBusy.set(true);
     this.deleteError.set('');
     try {
-      await firstValueFrom(this.api.delete(target.kind, schoolId, target.id));
+      await firstValueFrom(
+        this.api.delete(target.kind, schoolId, target.id, this.deletionRevision),
+      );
       this.deleting.set(null);
       if (target.kind === 'school') await this.router.navigate(['/schools']);
       else {

agiledancers-fe/src/app/shared/entity-editor.spec.ts

@@ -50,11 +50,33 @@ describe('EntityEditor', () => {
     const saved = vi.fn();
     component.saved.subscribe(saved);
     await component.save();
-    expect(api.saveSchool).toHaveBeenCalledWith({ name: 'Studio' }, undefined);
+    expect(api.saveSchool).toHaveBeenCalledWith({ name: 'Studio' }, undefined, undefined);
     expect(saved).toHaveBeenCalledOnce();
     expect(component.busy()).toBe(false);
   });
 
+  it('retains the revision from opening the editor across background refreshes', async () => {
+    api.saveDancer.mockReturnValue(of({ id: 3 }));
+    const fixture = TestBed.createComponent(EntityEditor);
+    fixture.componentRef.setInput('target', {
+      kind: 'dancer',
+      value: { id: 3, name: 'Sam', birthDate: '2010-01-01' },
+    });
+    fixture.componentRef.setInput('schoolId', 7);
+    fixture.componentRef.setInput('revision', 4);
+    const component = fixture.componentInstance;
+    component.ngOnInit();
+    fixture.componentRef.setInput('revision', 5);
+    component.name = 'Sam edited';
+    await component.save();
+    expect(api.saveDancer).toHaveBeenCalledWith(
+      7,
+      { name: 'Sam edited', birthDate: '2010-01-01' },
+      3,
+      4,
+    );
+  });
+
   it('keeps the editor open and preserves input when saving fails', async () => {
     api.saveSchool.mockReturnValue(throwError(() => new HttpErrorResponse({ status: 0 })));
     const component = editor({ kind: 'school' });
@@ -116,6 +138,7 @@ describe('EntityEditor', () => {
       7,
       expect.objectContaining({ preferredDayParts: 1 }),
       undefined,
+      undefined,
     );
   });
 

agiledancers-fe/src/app/shared/entity-editor.ts

@@ -174,6 +174,8 @@ import { DialogFrame } from './dialog-frame';
 })
 export class EntityEditor implements OnInit {
   readonly target = input.required<EditorTarget>();
+  readonly revision = input<number>();
+  private originalRevision?: number;
   readonly schoolId = input<number>();
   readonly shows = input<Show[]>([]);
   readonly closed = output<void>();
@@ -207,6 +209,7 @@ export class EntityEditor implements OnInit {
     return `${labels[this.target().kind]} ${this.target().value ? 'bewerken' : 'toevoegen'}`;
   }
   ngOnInit(): void {
+    this.originalRevision = this.revision();
     const target = this.target();
     if (!target.value) return;
     if (target.kind === 'group') {
@@ -298,13 +301,14 @@ export class EntityEditor implements OnInit {
     let request: Observable<unknown>;
     switch (target.kind) {
       case 'school':
-        request = this.api.saveSchool({ name: this.name.trim() }, id);
+        request = this.api.saveSchool({ name: this.name.trim() }, id, this.originalRevision);
         break;
       case 'dancer':
         request = this.api.saveDancer(
           schoolId!,
           { name: this.name.trim(), birthDate: this.date },
           id,
+          this.originalRevision,
         );
         break;
       case 'group':
@@ -318,6 +322,7 @@ export class EntityEditor implements OnInit {
             styles: this.selectedStyles,
           },
           id,
+          this.originalRevision,
         );
         break;
       case 'show':
@@ -329,6 +334,7 @@ export class EntityEditor implements OnInit {
             preferredDayParts: this.preferredDayParts,
           },
           id,
+          this.originalRevision,
         );
         break;
     }

agiledancers-fe/src/app/shared/group-members.ts

@@ -57,6 +57,8 @@ import { DialogFrame } from './dialog-frame';
   `,
 })
 export class GroupMembers implements OnInit {
+  readonly revision = input<number>();
+  private originalRevision?: number;
   readonly schoolId = input.required<number>();
   readonly group = input.required<DanceGroup>();
   readonly dancers = input.required<Dancer[]>();
@@ -70,6 +72,7 @@ export class GroupMembers implements OnInit {
   );
   private readonly api = inject(SchoolApi);
   ngOnInit(): void {
+    this.originalRevision = this.revision();
     this.memberIds.set([...this.group().dancerIds]);
   }
   async toggle(dancerId: number, event: Event): Promise<void> {
@@ -82,7 +85,10 @@ export class GroupMembers implements OnInit {
     this.busy.set(true);
     this.error.set('');
     try {
-      await firstValueFrom(this.api.membership(this.schoolId(), this.group().id, dancerId, add));
+      await firstValueFrom(
+        this.api.membership(this.schoolId(), this.group().id, dancerId, add, this.originalRevision),
+      );
+      if (this.originalRevision !== undefined) this.originalRevision++;
       this.memberIds.update((ids) =>
         add ? [...ids, dancerId] : ids.filter((id) => id !== dancerId),
       );

agiledancers-fe/src/app/shared/schedule-editor.spec.ts

@@ -57,7 +57,7 @@ describe('ScheduleEditor', () => {
     const draft = { ...show, finalized: false, violations: ['Group 1 requires 1 dayparts.'] };
     api.saveAssignments.mockReturnValue(of(draft));
     await component.save();
-    expect(api.saveAssignments).toHaveBeenCalledWith(7, 4, [[2], [3]]);
+    expect(api.saveAssignments).toHaveBeenCalledWith(7, 4, [[2], [3]], undefined);
     expect(component.current()).toEqual(draft);
     expect(component.dirty()).toBe(false);
     expect(api.finalize).not.toHaveBeenCalled();

agiledancers-fe/src/app/shared/schedule-editor.ts

@@ -113,6 +113,8 @@ import { DialogFrame } from './dialog-frame';
 export class ScheduleEditor implements OnInit {
   readonly show = input.required<Show>();
   readonly groups = input.required<DanceGroup[]>();
+  readonly revision = input<number>();
+  private originalRevision?: number;
   readonly schoolId = input.required<number>();
   readonly closed = output<void>();
   readonly saved = output<void>();
@@ -124,6 +126,7 @@ export class ScheduleEditor implements OnInit {
   assignments: number[][] = [];
 
   ngOnInit(): void {
+    this.originalRevision = this.revision();
     this.current.set(this.show());
     this.assignments = this.show().dayParts.map((p) => [...p.danceGroupIds]);
   }
@@ -162,9 +165,15 @@ export class ScheduleEditor implements OnInit {
     try {
       const result = await firstValueFrom(
         finalize
-          ? this.api.finalize(this.schoolId(), this.show().id)
-          : this.api.saveAssignments(this.schoolId(), this.show().id, this.assignments),
+          ? this.api.finalize(this.schoolId(), this.show().id, this.originalRevision)
+          : this.api.saveAssignments(
+              this.schoolId(),
+              this.show().id,
+              this.assignments,
+              this.originalRevision,
+            ),
       );
+      if (this.originalRevision !== undefined) this.originalRevision++;
       this.current.set(result);
       this.assignments = result.dayParts.map((p) => [...p.danceGroupIds]);
       this.dirty.set(false);

agiledancers-fe/src/app/shared/school-transfer.ts

@@ -10,6 +10,7 @@ interface Preview {
   shows: number;
   existingId: number | null;
   existingName: string | null;
+  existingRevision: number | null;
 }
 @Component({
   selector: 'app-school-transfer',
@@ -117,7 +118,12 @@ export class SchoolTransfer {
       const query = p.existingId === null ? '' : `?replaceId=${p.existingId}`;
       await firstValueFrom(
         this.http.post(`${this.base}/import${query}`, this.json, {
-          headers: { 'Content-Type': 'application/json' },
+          headers: {
+            'Content-Type': 'application/json',
+            ...(p.existingRevision === null
+              ? {}
+              : { 'X-School-Revision': String(p.existingRevision) }),
+          },
         }),
       );
       this.cancel();

ci/runner/agiledancers-runner.service

@@ -1,19 +0,0 @@
-[Unit]
-Description=Agiledancers Gitea Actions runner
-After=network-online.target
-Wants=network-online.target
-
-[Service]
-Type=simple
-WorkingDirectory=%h/.local/share/agiledancers-runner
-EnvironmentFile=%h/.config/agiledancers-runner/environment
-ExecStartPre=/usr/bin/env java %h/.local/share/agiledancers-runner/WaitForDocker.java 120
-TimeoutStartSec=150
-ExecStart=%h/.local/bin/act_runner daemon --config %h/.local/share/agiledancers-runner/config.yaml
-Restart=on-failure
-RestartSec=10
-KillSignal=SIGTERM
-TimeoutStopSec=150
-
-[Install]
-WantedBy=default.target

ci/runner/config.yaml

@@ -6,6 +6,6 @@ runner:
   timeout: 2h
   shutdown_timeout: 2m
   labels:
-    - agiledancers-mini-pc:host
+    - mini-pc:host
 cache:
   enabled: false

ci/runner/runner.service

@@ -0,0 +1,19 @@
+[Unit]
+Description=mini-pc Gitea Actions runner
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+WorkingDirectory=%h/.local/share/mini-pc-runner
+EnvironmentFile=%h/.config/mini-pc-runner/environment
+ExecStartPre=/usr/bin/env java %h/.local/share/mini-pc-runner/WaitForDocker.java 120
+TimeoutStartSec=150
+ExecStart=%h/.local/bin/act_runner daemon --config %h/.local/share/mini-pc-runner/config.yaml
+Restart=on-failure
+RestartSec=10
+KillSignal=SIGTERM
+TimeoutStopSec=150
+
+[Install]
+WantedBy=default.target