Give multi-repo Codex runs every repository's AGENTS.md

[ppXD]

Summary

• The gap. Codex 0.142.2 reads a project doc from its cwd and the directories above it, never from one below. A multi-repo run works at the workspace root, which is no repository, so no repository's AGENTS.md reached the model. Claude runs at the same root load every repository's memory.
• The fix. When the cwd is not itself a repository, CodexRepositoryGuides gives each repository strictly inside it the doc Codex itself would pick at its root.
  • An AGENTS.override.md wins over AGENTS.md, whether it is a file or a link, even an empty one.
  • The doc is cut at 32 KiB (project_doc_max_bytes) and decoded lossily.
  • CodexHarness appends each doc after the persona and the operating contract in CODEX_HOME/AGENTS.md, under --- project-doc (<repository>/<file>) ---. There it reaches the model in the same instruction block as a single-repo project doc.
  • An @ path, ~ path or $skill in a doc attaches nothing.
• Containment.
  • A doc that resolves outside the workspace is left out, checked with PhysicalPath, the walker Claude's memory guard uses. So is one whose repository path holds characters the separator cannot carry.
  • Files open no-follow, non-blocking and only if regular.
  • What was left out or cut is said once through the launch notices.
  • A run whose cwd is a repository writes the same AGENTS.md as before.

Test plan

• Unit: the full suite passes (12083 passed, 1 skipped). Cases cover:
  • single-repo AGENTS.md byte-identical;
  • appendix format and order;
  • override precedence;
  • the truncation notice;
  • an outside link refused;
  • MaxProjectDocBytes pinned.
• Integration (Postgres): RealHarnessCodexMultiRepoGuidesTests with RealHarnessWorkspaceMemoryTests, 9/9.
• E2E on macOS, real Codex 0.142.2 and Claude 2.1.263: RepositoryConfigE2ETests 15/15. The workflow's repository-config gate, run against the TRX, prints All 15 repository-config E2E cases and 15 markers ran and passed.
  • A_multi_repo_codex_run_reads_every_repositorys_agents_md requires the first repository's doc and the second's override in the first request's instruction block, after the contract, each once.
  • The second repository's plain doc and the third's outside-linked doc reach no request. The outside target now sits under /etc, where a confined run could still read it, so in the root lane too its absence is the containment check's doing.
  • The single-repo Codex arm requires its repository's doc exactly once.
• CI root sandbox lane: floor 108, marker agents-md codex-cli multi-repo