feat(mcp): add gittensory_check_test_evidence tool (deterministic coverage-gap self-check)

[JSONbored]

The engine already has a deterministic changed-path→test-evidence classifier (src/signals/test-evidence.ts) and slop uses it to flag missing test coverage (src/signals/slop.ts:263-277), but there is no dedicated MCP tool an agent can call to ask 'do my changed files carry enough test evidence?' before opening a PR. Surface the classifier as a standalone metadata-only MCP tool (paths + optional test-file paths in; coverage-gap band + guidance out).

Deliverables

• Define an inputSchema (changed paths, optional added/modified test paths) as a zod shape in src/mcp/server.ts
• Handler calls the test-evidence classifier and returns the coverage-gap classification + actionable guidance strings (no source content required)
• zod outputSchema for the classification result
• Tests: code-only-no-tests path, code+tests path, docs-only path, and the classifier's threshold branches

References

• src/signals/test-evidence.ts:18
• src/signals/slop.ts:263
• src/mcp/server.ts:1197

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size: S · held for later release (gittensor:feature once activated)

[linear-code]

JSO-2336

[RealDiligent]

Follow-up from merged #3889 (isSourcePath): the MCP score-preview (.mjs/.py) and packages/gittensory-mcp/lib/local-branch.js mirrors still omit .kts from isCodeFile while isTestPath already recognizes .kts tests. Planning a parity PR unless an upstream tracking issue already exists.

[RealDiligent]

Update: PR #3921 (CI green, Gittensory approve) was auto-closed because this issue is maintainer-reserved. The MCP .kts classifier parity fix is ready on RealDiligent:fix/mcp-iscodefile-kts-parity (rebased on current main, 120 targeted tests pass).

Could a maintainer please open a contributor-eligible upstream tracking issue (open, unassigned, gittensor:bug, not maintainer-only) for this follow-up so we can file a fresh PR with Closes #…? RealDiligent cannot CreateIssue on this repo.