CH-003: CI builds the native client on Linux only

[flemming-n-larsen]

Acceptance brief

• Plan item and whether it remains wanted: plan-less; follows CH-002 as scoped by the maintainer and serves G-001, which remains wanted.
• The vision this change proceeds under: VIS-001 — Enable community-run ranked Tank Royale battles (status: draft, inferred).
• Added or changed criteria: none.
• What becomes binding on merge: ADR-002 (inferred, agent-authored) — CI builds and tests the native client on Linux only; native Windows and macOS runs stay supported but are no longer CI-tested. The build (windows-latest) and build (macos-latest) checks disappear and the job is reported as build. No unaccepted base.

A green build, complete form, or confident agent is not evidence that this outcome is wanted or that the criteria reflect reality. Keep this brief to one screen; split a change rather than hiding material meaning.

Summary

.github/workflows/build.yml's build job runs only on ubuntu-latest; the OS matrix, the Windows-only gradlew.bat step, and the Linux-only condition on the artifact upload are removed. The docker job is unchanged. The README states that native Windows and macOS runs are not CI-tested, and the architecture overview links ADR-002. No changelog entry: CI platform scope is not user-facing. Editorial: the CH-002 launcher-default entry moves from [Unreleased] to [0.1.0], because the changelog tracks the released image and the launchers are not part of it.

Documentation impact: README.md, docs/architecture/README.md, and docs/decisions/ (ADR-002 and index) changed; docs/design/README.md needed no change.

Verification

• clue validate --forbid-changes: OK
• git diff --check origin/main HEAD: clean
• build.yml parses; build has runs-on: ubuntu-latest, no strategy, no OS conditions

Cliewen proposal

• Change ID: CH-003
• Plan item served: plan-less (follows CH-002, serves G-001)
• Proposal location: /changes/CH-003-ci-native-build-linux-only/proposal.md (in commit a8f9bf8; deleted in digest)
• Agentic review mode, reviewed commit, and pass count: context-isolated; 6502341; 1 completed pass (an earlier pass on f5d9dcf was stopped before returning)
• Outstanding advisory findings:
  • README.md:68 says the container image is "the tested path on every host OS", but the docker job verifies it only on Linux with Docker; Windows/macOS container use is manually verified, not CI-tested (as README line 92 says). Reword to "the CI-tested path (verified on Linux)".
  • ADR-002's rationale says "the Linux build covers the supported default path on every host OS", but the image is verified by the docker job, on Linux only. Same overstatement; the decision is unaffected.
  • Branch protection: main has no required status checks or rulesets, so the job rename from build (ubuntu-latest) to build breaks nothing.
• Hosted head reviewed before this update: 6502341 (draft)
• Outstanding actionable findings: none

Traceability and Decisions

• Acceptance criteria or capability meaning changed: none
• Decision records added or changed: ADR-002
• Constraints assessed: C-001 (no hard-wrapped Markdown) — satisfied

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https://claude.ai/code/session_01KwJVGH7ftyX2ThQ2wMCLQK