Define multiplayer development gates and isolated U1 preflight

[VirtualAdam]

Description

Closes #318 after normal review, integration and explicit contract adoption.
Refs #240 and #239; does not close U1 or the multiplayer epic.

• Define a proposed replacement acceptance contract with 14 new requirement IDs and 37 test families grounded in the published backlog, not a reconstructed or previously approved R1-R14/M01-M37 document.
• Separate G0 development entry, G1 owner-only full-stack baseline, G2 qualified shared-execution admission and G3 release. The bounded G0 milestone replaces full U1 as the development prerequisite for Multiplayer U2: add durable membership, ownership, and sharing contracts #241; U1 remains an applicable runtime and release gate.
• Add read-only Windows fixture preflight checks for source, disjoint paths, protected/occupied ports, tool availability and registry configuration, with explicit blockers rather than acceptance claims.
• Add dependency-free regression coverage and wire it into the existing Windows CI lane. Update the handbook and evaluation documentation.

Base: 30ec3fab6acd566cc1fc1e574c8a6343d0ce0596.
Head: 6fe6668479417a2df43dbe1f7e471b4dec21457a.
Write scope: six files: .github/workflows/ci.yml, docs/EVALS.md, docs/MULTIPLAYER_ACCEPTANCE_V1.md, docs/README.md, tools/qa_multiplayer_preflight.ps1, and tools/qa_multiplayer_preflight.test.ps1.

No backend, database migration, dependency manifest, lockfile, credential or deployed service changes. No merge, auto-merge or deployment requested.

Native-capability check and limits

The repository already has local_stack.psm1 process ownership, owned_test_stack.mjs scoped restart checks and existing E2E drivers. This contribution does not duplicate them. The missing capability is a read-only, explicitly scoped fresh-U1-fixture preparation report plus a published replacement acceptance contract.

The preflight uses existing Git, command discovery and Windows listener inventory. Rust/pnpm shims are not executed because they may download toolchains. A preparation pass is not source/build attestation, OS isolation, private artifact storage, independent browser identity or permission to launch. The actual U1 fixture, OIDC integration, M34-equivalent hostile matrix and exact owned shutdown remain open.

Type of change

• New feature (non-breaking prerequisite tooling)
• This change requires a documentation update

How Has This Been Tested?

From the contribution worktree:

pwsh -NoLogo -NoProfile -NonInteractive -File .\tools\qa_multiplayer_preflight.test.ps1
node --test --test-reporter=dot .\tools\owned_test_stack.test.mjs .\tools\fixture_source_identity.test.mjs
node .\tools\check_migrations.mjs
git diff --cached --check

• Focused PowerShell path/port/source/tool/registry/read-only regression passed.
• 55 existing Node source/ownership regressions passed.
• Migration check passed: 41 migrations, immutable checksums.
• Staged whitespace check passed after normalizing the three new files to repository LF convention.
• Spec structure checked: 14 unique sequential requirement IDs and 37 unique sequential test-family IDs.
• An actual read-only preflight returned exit 2 / blocked for missing Rust/Cargo, missing pnpm, unspecified approved registry and then-uncommitted source; it did not create the planned QA root. This is a truthful preparation result, not runtime acceptance.
• An earlier trailing-dot path regression failed; the owned synthetic fixture was retained. Raw path components are now checked before normalization and the corrected regression passed.

Not run locally: cargo fmt, Clippy, Rust workspace tests, pnpm build:web, pnpm lint:web because Cargo/pnpm are absent. No new installation, full-stack run, browser test, hostile canary, production sign-in, physical-device test or provider inference was performed. Screenshots are not applicable to this CLI/docs slice. Hosted CI verdicts must be assessed on the exact PR head.

Test configuration: Windows, PowerShell 7.4+ requirement, Node 22.14.0, Docker read-only connectivity 29.8.0. No SDK/provider runtime was used. Tests use synthetic directories and stubbed prerequisite observations; these are not evidence for the original U1 gate.

Checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests for the scoped prerequisite behavior
• Focused new and related existing tests pass locally
• Full repository gates and hosted CI verified
• Required independent review and contract adoption complete
• Full U1 runtime acceptance (intentionally outside this PR)

This is a draft review contribution. Existing runtime gates, ownership, retained office data and the unresolved #242 browser-auth review are preserved.

[Copilot]

🟡 Changes recommended

The preflight can falsely accept invalid or aliased Windows roots as safe and disjoint.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

Defines multiplayer acceptance gates and adds a preparation-only Windows U1 fixture preflight.

Changes:

• Introduces 14 requirements, 37 test families, and G0–G3 gates.
• Adds read-only preflight checks with regression coverage.
• Integrates the regression into Windows CI and updates documentation.

File summaries

File	Description
.github/workflows/ci.yml	Runs the preflight regression on Windows.
docs/EVALS.md	Documents preflight scope and limitations.
docs/MULTIPLAYER_ACCEPTANCE_V1.md	Defines the replacement acceptance contract.
docs/README.md	Links the new contract.
tools/qa_multiplayer_preflight.ps1	Implements prerequisite checks and reporting.
tools/qa_multiplayer_preflight.test.ps1	Tests path, port, source, tool, and registry guards.

Review details

• Files reviewed: 6/6 changed files
• Comments generated: 1
• Review effort level: Balanced

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