Session Instructions Loader

Codex reads AGENTS.md from the detected project root down to the current working directory. The default project root marker is .git, so workspace-level instructions above a Git repository can be skipped.

This plugin adds a SessionStart hook that injects additional instruction files as context:

• it runs on session startup, resume, clear, and the post-compaction SessionStart event so rebuilt threads regain the same supplemental instructions;
• inside a Git repository, it can read AGENTS.md files above the Git root;
• inside a Git worktree, it resolves the original repository root referenced by the worktree .git file and reads AGENTS.md files above that root;
• outside Git, it can read parent directories above the current working directory;
• it stops ancestor discovery at Codex's own .codex state directory, so managed worktrees do not inherit ~/.codex/AGENTS.md;
• it also reads repo-local files listed in .codex/session-instructions-loader.json;
• ancestorLevel controls upward AGENTS.md discovery; it defaults to 0 which disables ancestor discovery, 1 means only the repository's parent directory is checked, and -1 traverses up to the user's home directory;
• it never writes files and silently exits when no instruction file exists.

Example config:

{
  "ancestorLevel": 1,
  "extraFiles": [
    ".claude/CLAUDE.md"
  ]
}

The injected context is capped at 64 KiB total to avoid oversized session-start payloads.