Codiff

Codiff

Use Codiff either to review a narrative walkthrough of a code change or to hand a Markdown plan to the user for visual editing before execution.

You write the JSON yourself because you already hold the conversation that produced the change. Codiff owns the format and authoring guidance, so this skill only handles the handoff.

Choose The Mode

• Use plan share mode for $codiff plan share, or when a share request is clearly about the proposed plan in the current discussion.
• Use walkthrough share mode when the request includes share, upload, link, URL, web, or browser wording and is about code changes. An underspecified $codiff share defaults to a walkthrough.
• Use plan mode for $codiff plan or when the user explicitly asks to edit or approve a plan in Codiff before execution.
• Use desktop mode for plain $codiff, /codiff, "open Codiff", or "show me Codiff".
• In share mode, only pass --open when the user explicitly asks to open the resulting share in a browser. Otherwise return the URL without opening it.

Bundled Launcher

Before running any launcher command, set SKILL_DIR to the absolute directory containing this SKILL.md, then invoke the bundled script through that path:

SKILL_DIR="/absolute/path/to/skills/codiff"
node "$SKILL_DIR/scripts/open-codiff.mjs" ...

The shell cwd is normally the user's project, so do not invoke a project-relative scripts/open-codiff.mjs path.

Plan Mode

1. Write the complete proposed plan to a Markdown file. Use a unique temporary file outside the repository unless the user named a canonical plan file.

2. Make the intended next action explicit in the document. The user should be able to edit, remove, or reorder any part of the plan.

3. Open the blocking handoff:

   node "$SKILL_DIR/scripts/open-codiff.mjs" --plan /tmp/codiff-plan-<id>.md
   

4. Wait for Codiff to return. status: "done" means the user clicked Done. status: "closed" means the user closed the window after Codiff flushed the file and comments. A canceled handoff means the app could not complete the handoff and must not be treated as approval.

5. Read the CODIFF_PLAN_RESULT JSON emitted when Codiff closes. Re-read the entire Markdown file and process every thread in review.threads whose status is "open". Treat edits, additions, removals, reordered steps, and open comments as user direction. Use quoted anchor context for detached comments. Resolved comments are retained history and must not be processed again.

6. After successfully applying one or more open comments, acknowledge only the handled thread IDs using the exact reviewPath from CODIFF_PLAN_RESULT:

   node "$SKILL_DIR/scripts/open-codiff.mjs" --resolve-plan-comments "<reviewPath>" <thread-id>...
   

   Do not resolve comments that were ambiguous, deferred, or not applied.

7. For status: "done", execute the edited plan when the next action is clear. For status: "closed", continue only when documentChanged is true or unresolved comments contain user direction; otherwise treat the close as cancellation. If the feedback is materially ambiguous, ask one focused question before changing code.

The edited Markdown file is the feedback. Do not require comments, annotations, or a separate approval document.

Plan Share Mode

1. Write the complete plan to a Markdown file, using the same authoring rules as plan mode.

2. Upload it without opening a blocking desktop handoff:

   node "$SKILL_DIR/scripts/open-codiff.mjs" --plan /tmp/codiff-plan-<id>.md --share
   

3. Add --open only when the user explicitly asks to open the shared plan in a browser.

4. Return only the /p/… URL printed by the command.

Walkthrough Workflow

1. Get the current guidance from Codiff. It explains the data model and prints the JSON schema:

   node "$SKILL_DIR/scripts/open-codiff.mjs" --guide
   

2. Pick the change. Default to the staged diff (git diff --staged). If the user named a target such as a commit, HEAD, a PR/MR, a range, or a path, use that. If nothing is staged, fall back to the working tree (git diff) and say so.

3. Author the JSON per the guide and write it to a unique temporary file outside the repository, such as $TMPDIR/codiff-walkthrough-<id>.json.

4. Complete the selected handoff.

   Desktop mode:

   node "$SKILL_DIR/scripts/open-codiff.mjs" --file /tmp/codiff-walkthrough-<id>.json /path/to/repository
   

   Share mode:

   node "$SKILL_DIR/scripts/open-codiff.mjs" --share --file /tmp/codiff-walkthrough-<id>.json /path/to/repository
   

   Share and open in the default browser:

   node "$SKILL_DIR/scripts/open-codiff.mjs" --share --open --file /tmp/codiff-walkthrough-<id>.json /path/to/repository
   

   Forward an explicit target after the flags:

   node "$SKILL_DIR/scripts/open-codiff.mjs" --share --file /tmp/codiff-walkthrough-<id>.json HEAD /path/to/repository
   node "$SKILL_DIR/scripts/open-codiff.mjs" --share --file /tmp/codiff-walkthrough-<id>.json mr 123 /path/to/repository
   

   The share command prints the final walkthrough URL to stdout. When the cached Cloudflare Access token is missing or unusable, Codiff automatically opens the system browser for authentication and resumes after sign-in. This authentication browser is independent of --open, which only controls whether the completed walkthrough is opened.

   Agent integration: The launcher passes CODEX_THREAD_ID to Codiff in desktop mode and identifies shared walkthroughs as authored by Codex.

   Codiff validates and repairs the document against the live diff, so anchors that drift are pinned to a real section rather than dropped.

Emit walkthrough JSON only into the temporary file. In desktop walkthrough mode, do not summarize the conversation back to the user. In walkthrough share mode, respond with the URL printed by the command. In plan share mode, respond with the shared plan URL. In plan mode, continue from the edited Markdown after the blocking handoff returns.