fix(coding-agents): stop unsafe gitlog cleanup

[r266-tech]

Summary

• stop coding-agents from enumerating and deleting bank-wide source:git-log documents during sync
• make every internal multi-tag strategy probe use all_strict, while preserving listDocumentIds()'s existing public default
• treat a git-log snapshot as current only when the current-HEAD query contains this repository's canonical document; otherwise perform an idempotent upsert

Fixes #3877.

Why

The document listing endpoint can include untagged documents for the legacy inclusive all mode. The old deepen path then treated every returned non-canonical document as stale and deleted it. Because document deletion cascades to facts, a routine coding-agents sync could remove unrelated memories from a shared bank.

This change removes that destructive cleanup entirely. Git-log sync now owns only its canonical document and never deletes other document IDs.

Compatibility and remaining limitation

The optional tags_match parameter defaults to all, matching the existing client behavior for external callers. Coding-agents' internal strategy checks opt into all_strict explicitly.

Canonical git-log IDs remain gitlog:<repoName> for backward compatibility. Consequently, unrelated same-named repositories or forks can still share that legacy ID; changing the namespace safely requires a separate ownership/migration design. This patch prevents cross-document deletion but does not attempt that migration.

Validation

• npx tsc --noEmit
• npx vitest run src/core/hindsight.test.ts src/core/git.gitlog.test.ts src/core/status.test.ts src/core/session-start.test.ts (69 tests)
• npm test (663 tests)
• npm run build
• git diff --check

The repository-wide lint hook could not load the control-plane @eslint/js dependency from this sparse worktree; the package typecheck, complete test suite, build, and diff checks pass.

[strix-security]

Strix Security Review

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No security issues found.

_{Updated for c4c9524.}

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Reviewed by Strix
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[koriyoshi2041]

Verified at 762a6f8. The destructive bank-wide cleanup is gone, internal tag probes use strict matching, and the current-HEAD check now requires this repository's canonical document ID. I also ran the 69 focused tests, TypeScript typecheck, package build, and diff hygiene successfully.