Add Content mounted local source identities

[3mdistal]

Summary

• Registers local-folder and github-url as mounted Content source/workspace identities alongside Builder CMS sources.
• Preserves repo/Git truth semantics: mounted local/GitHub sources expose identity/system fields and read-only capabilities, but do not seed fake rows, claim title/property truth, refresh, clone, commit, push, or make local MDX the default docs-team path.
• Surfaces source identity through list/search/command/sidebar scope so Builder CMS, local-file, local-folder, and GitHub URL sources can coexist without blurring the active source/workspace.
• Adds agent guidance and a Content changelog entry for the user/agent-facing source registration behavior.

Verification

• pnpm vitest --run actions/_database-source-utils.test.ts actions/content-database-source-actions.test.ts actions/attach-content-database-source.db.test.ts actions/list-content-databases.db.test.ts actions/_local-file-documents.test.ts app/lib/content-command-search.test.ts — 6 files passed, 79 tests passed.
• pnpm --filter content typecheck — passed. Existing envFile deprecation warnings only.
• pnpm --filter content test — passed. 89 files passed, 1 skipped; 975 passed, 3 expected fail, 5 skipped.
• pnpm action search-documents '{"query":"__codex_local_github_scope_smoke__","sourceScope":"local-files","limit":1}' — passed, returned { documents: [] }.
• pnpm action list-content-databases '{"query":"__codex_local_github_scope_smoke__","limit":1}' — passed, returned { databases: [] }.
• git diff --check — passed.

Local Claude Code Opus Review

• Initial adversarial review log: .task-sweep/logs/claude-opus-review-20260701-144509.log with output .task-sweep/logs/claude-opus-review-output-20260701-144509.jsonl.
• Review found three blockers: mounted sources seeded fake rows/title ownership, role-change behavior was inconsistent for mounted sources, and mounted sources advertised refresh without implementation.
• Addressed all three blockers with implementation and DB tests.
• Follow-up adversarial review log: .task-sweep/logs/claude-opus-followup-20260701-145433.log with output .task-sweep/logs/claude-opus-followup-output-20260701-145433.jsonl.
• Follow-up verdict: no blockers; B1/B2 fixed, B3 fixed at the capability layer. Non-blocking docs/source-field cleanup called out by the review was also addressed before this PR was opened.

Scope Notes

• Draft PR only. Do not merge or enable auto-merge from this worker lane.
• This remains the local folder + GitHub URL workspace wedge only.
• No full Git workflow automation, no OpenKnowledge parity chase, no Notion/Analytics/HTML/custom mini-app expansion, and no shift of the docs-team default path away from Builder CMS dogfooding this week.

[github-actions]

Visual recap — skipped

The visual recap job did not run for this pull request. This is informational only and does not block the PR.

Recap skipped for 9a5bef5: draft PR.

[3mdistal]

CI pulse update: Lint & format failed in pnpm fmt:check because templates/content/AGENTS.md was intentionally kept compact during the prior mergeability cleanup. I updated the branch with current origin/main, let oxfmt format the guide table, and verified locally with pnpm fmt:check plus git diff --check HEAD~1 HEAD. PR remains draft-only; no ready/merge/auto-merge action taken.