fix(ce-code-review): stop the reviewer template from embedding the diff twice

[tmchow]

Every ce-code-review reviewer prompt carried the changed-file list and the full diff twice, then ended with a note telling the reviewer that inline content "may be file paths" to Read from disk. The closing note of the template's <review-context> block named {file_list} and {diff} in slot syntax, so prompt assembly filled them a second time; the reporter measured the second copy at 33% of a nine-reviewer run's payload, and one reviewer stopped to verify the contradiction. The note now refers to the Changed files: and Diff: labels the reviewer actually sees after substitution and states the condition: inline content is authoritative, a lone staged path is Read. This matches the shape the validator template already used.

A contract test pins each placeholder to exactly one occurrence inside the fenced template, so a future mention of {diff} in the note fails bun run test.

Fixes #1509

Validation

bun run test (3540 pass), bun run release:validate clean. The new test fails on the old template line and passes on the new one.

Fresh-agent eval of the reviewer subagent, read-only, against a throwaway repo with a 2-file diff. Prompts were assembled from the real template (pre = main, post = this branch) by filling every {slot}; the pre prompt reproduces the bug (diff present twice). Three arms on Claude (claude -p) and Codex (codex exec --sandbox read-only):

Arm	Claude	Codex
pre, inline diff	Reviewed inline diff; absorbed the false note silently (no path reads, no contradiction reported)	Same; re-derived the diff from git diff rather than trusting the prompt
post, inline diff	Reviewed inline diff; no path reads	Same; also re-derived from git and ran a node probe
post, staged paths	First tool calls: Read diff.txt, Read files.txt, then reviewed	First command: sed both staged files, then reviewed

No regression on either host; the staged-path instruction still fires on both. The strong tiers absorbed the old contradiction rather than acting on it (matching 8 of 9 reviewers in the report), so this eval shows the fix holds rather than a before/after flip; the reporter's testing reviewer that halted to verify is the observed failure the rewrite removes.

Security Disclosure

No security-relevant changes.

Agent Disclosure

• Model: Claude Code · claude-fable-5

https://claude.ai/code/session_012uPY9QcVF4ueBgrpegPcvC

[cursor]

PR Summary

Low Risk
Prompt-template wording and a contract test only. No auth, data handling, or runtime logic changes; residual risk is that reviewers misread staged path vs inline content, which the new note is meant to prevent.

Overview
Stops ce-code-review reviewer prompts from substituting {file_list} and {diff} a second time. The closing note in subagent-template.md used those names in slot syntax, so prompt assembly pasted the full file list and diff twice (a large share of multi-reviewer payload).

The note now refers to the Changed files: and Diff: labels after substitution: inline content is authoritative; a lone staged path should be Read. A contract test requires each of those placeholders to appear only once inside the fenced template.

^{Reviewed by Cursor Bugbot for commit c85d44a. Bugbot is set up for automated code reviews on this repo. Configure here.}