Build the EMF scaffold: the Maven reactor, its gates and its CI job #80

Parent

#78

What to build

The model-driven implementation gets a build before it gets any EMF code, so the walking skeleton lands into gates that already hold. This is the EMF scaffold: no EMF, OCL, Xtext, QVTo or Acceleo dependency yet, and no Tycho.

• A Maven reactor inside the coursework directory, run through a Maven wrapper that commits no jar and pins a Maven 3.9 release, on the JDK named by a version file beside it (21, Temurin in CI). Coordinates dev.jorisjonkers.deploykit.emf, version 0.1.0-SNAPSHOT, never published: nothing declares a distribution target.
• One module, parity, holding the first real code the parity contract needs: an RFC 8785 canonical JSON writer, with its tests. The other five modules arrive with their stage.
• Gates that match what the estate's JVM repositories actually enforce, plus Java-shaped equivalents where the estate has only Kotlin tooling: the enforcer (Java 21, Maven 3.9, dependency convergence), compiler warnings as errors with every lint on, Spotless with palantir-java-format, JUnit 6 with AssertJ, ArchUnit enforcing the module dependency direction the coursework architecture states, JaCoCo at a line-coverage floor bound to verify, and PIT mutation testing with a break threshold. Both thresholds are set from the first local measurement and only rise.
• Rejected, with the reason recorded: SpotBugs, Error Prone, NullAway, SBOM generation and signing. Nothing in the estate runs them for JVM code, and CodeQL covers the security half.
• A new ADR 0115 in the coursework register records the gate set, the estate audit it came from, and that PIT is scoped to non-OSGi modules if Tycho breaks it.
• A list of Java witnesses for model behaviours (ADR 0114) and the JUnit check that holds it against the root behaviour ledger. It is green while no model row exists yet.
• A Maven-enforced rule list inside the coursework directory, each rule proved by a JUnit fixture.

Root wiring, each piece named in the sunset list:

• An emf CI job running the reactor's verify, required by Pipeline Complete, writing a one-line test, coverage and mutation summary into the job summary.
• CodeQL scans java-kotlin with build mode none, triggers on changes to the coursework directory, and ignores build output and generated sources through a config file.
• A root test that fails when a workflow calls the Maven wrapper against a POM that does not exist, or the reactor names a module that is not on disk. Two rule-ledger rows: the wiring check, and Java being scanned.
• release-please ignores the coursework directory, so its commits neither bump the npm package nor enter the changelog.
• Renovate groups the maven and maven-wrapper managers for the coursework directory through a local rule.
• Git ignore and attribute entries for Maven, a CODEOWNERS line, a README row, and the gates table in docs/architecture.md counting fifteen.
• CONTEXT.md defines EMF scaffold and Walking skeleton. Bootstrap keeps its meaning (the bootstrap set and order).
• The coursework architecture document names the scaffold as the change before the walking skeleton, gains a Gates section, and no longer calls coverage and mutation gates out of scope for Java.

Acceptance criteria

• The emf CI job runs the reactor's verify on JDK 21 and is in Pipeline Complete's needs.
• Weakening a canonical JSON test fails the build on the mutation threshold; removing one fails it on the coverage floor.
• A misformatted Java file fails Spotless, a compiler warning fails the build, and an import against the module direction fails ArchUnit.
• CodeQL reports a java-kotlin analysis on a pull request that touches only the coursework directory.
• The wiring test fails on a workflow naming a missing POM, and on a reactor module missing from disk.
• A feat: commit touching only the coursework directory produces no release-please change.
• ADR 0115 passes the coursework ADR lint, and npm run verify passes.

Blocked by

None (can start immediately).