dev/AGENTS.md

Rust/codex-rs

In the codex-rs folder where the rust code lives:

• Crate names are prefixed with codex-. For example, the core folder's crate is named codex-core
• When using format! and you can inline variables into {}, always do that.

Completion/build step

• Always validate using ./build-fast.sh from the repo root. This is the single required check and must pass cleanly.
• Policy: All errors AND all warnings must be fixed before you’re done. Treat any compiler warning as a failure and address it (rename unused vars with _, remove mut, delete dead code, etc.).
• Do not run additional format/lint/test commands on completion (e.g., just fmt, just fix, cargo test) unless explicitly requested for a specific task.
• NEVER run rustfmt

Strict Ordering In The TUI History

The TUI enforces strict, per‑turn ordering for all streamed content. Every stream insert (Answer or Reasoning) must be associated with a stable (request_ordinal, output_index, sequence_number) key provided by the model.

• A stream insert MUST carry a non‑empty stream id. The UI seeds an order key for (kind, id) from the event's OrderMeta before any insert.
• The TUI WILL NOT insert streaming content without a stream id. Any attempt to insert without an id is dropped with an error log to make the issue visible during development.

Commit Messages

• Review staged changes before every commit: git --no-pager diff --staged --stat (and skim git --no-pager diff --staged if needed).
• Write a descriptive subject that explains what changed and why. Avoid placeholders like "chore: commit local work".
• Prefer Conventional Commits with an optional scope: feat(tui/history): …, fix(core/exec): …, docs(agents): ….
• Keep the subject ≤ 72 chars; add a short body if rationale or context helps future readers.
• Use imperative, present tense: "add", "fix", "update" (not "added", "fixes").
• For merge commits, skip custom prefixes like merge(main<-origin/main):. Use a clear subject such as Merge origin/main: <what changed and how conflicts were resolved>.

Examples:

• feat(tui/history): show exit code and duration for Exec cells
• fix(core/codex): handle SIGINT in on_exec_command_begin to avoid orphaned child
• docs(agents): clarify commit-message expectations

Git Push Policy (Do Not Rebase On Push Requests)

When the user asks you to "push" local work:

• Never rebase in this flow. Do not use git pull --rebase or attempt to replay local commits.
• Prefer a simple merge of origin/main into the current branch, keeping our local history intact.
• If the remote only has trivial release metadata changes (e.g., codex-cli/package.json version bumps), adopt the remote version for those files and keep ours for everything else unless the user specifies otherwise.
• If in doubt or if conflicts touch non-trivial areas, pause and ask before resolving.

Quick procedure (merge-only):

• Commit your local work first:
  • Review: git --no-pager diff --stat and git --no-pager diff
  • Stage + commit: git add -A && git commit -m "<descriptive message of local changes>"
• Fetch remote: git fetch origin
• Merge without auto-commit: git merge --no-ff --no-commit origin/main (stops before committing so you can choose sides)
• Resolve policy:
  • Default to ours: git checkout --ours .
  • Take remote for trivial package/version files as needed, e.g.: git checkout --theirs codex-cli/package.json
• Stage and commit the merge with a descriptive message, e.g.:
  • git add -A && git commit -m "Merge origin/main: adopt remote version bumps; keep ours elsewhere (<areas>)"
• Run ./build-fast.sh and then git push

Command Execution Architecture

The command execution flow in Codex follows an event-driven pattern:

1. Core Layer (codex-core/src/codex.rs):

   • on_exec_command_begin() initiates command execution
   • Creates EventMsg::ExecCommandBegin events with command details

2. TUI Layer (codex-tui/src/chatwidget.rs):

   • handle_codex_event() processes execution events
   • Manages RunningCommand state for active commands
   • Creates HistoryCell::Exec for UI rendering

3. History Cell (codex-tui/src/history_cell.rs):

   • new_active_exec_command() - Creates cell for running command
   • new_completed_exec_command() - Updates with final output
   • Handles syntax highlighting via ParsedCommand

This architecture separates concerns between execution logic (core), UI state management (chatwidget), and rendering (history_cell).