AGENTS.md Within Size Limit

Codex caps the combined AGENTS.md instruction chain — global ~/.codex/AGENTS.md plus every AGENTS.md from the git root down to the working directory — at 32 KiB (32,768 bytes) by default, the project_doc_max_bytes setting. Content past the cap is silently truncated and never reaches the model, with no warning. Keep the eager AGENTS.md footprint under 32 KiB, or raise project_doc_max_bytes deliberately when you need more.

Antipatterns

• A large global ~/.codex/AGENTS.md that crowds repo-specific AGENTS.md rules out under the 32 KiB cap. Keep the global file small.
• Embedding documentation, examples, or data tables in AGENTS.md instead of splitting into nested-directory AGENTS.md files that load only when descended into.
• Assuming everything in a long AGENTS.md reaches the model — past 32 KiB it is dropped without notice.

Pass / Fail

Pass

AGENTS.md chain totaling ~18 KB:
  ~/.codex/AGENTS.md (4 KB) + repo AGENTS.md (14 KB)
Total: ~18 KB -- within the 32 KiB cap; nothing truncated.

Fail

AGENTS.md chain totaling ~40 KB:
  ~/.codex/AGENTS.md (28 KB) + repo AGENTS.md (12 KB)
Total: ~40 KB -- Codex silently drops ~8 KB; the repo's own rules may never load.

Limitations

Counts the eager AGENTS.md footprint against Codex's default 32 KiB project_doc_max_bytes. A project that raises project_doc_max_bytes in config.toml has a higher real cap; this rule assumes the default.