fix(review): unbreak /review slash command poisoned by \!\` sequence

[tend-agent]

Summary

Every /tend-ci-runner:review invocation has been silently broken since PR #217 merged at 2026-04-10 20:07 UTC. PRs #225–#233 all received zero reviews from the bot — the review runs report success but the session artifacts show no assistant turn at all. This PR removes the poison and restores reviews.

Root cause

PR #217 (fix(ci-runner): replace if-not polling loop with || to avoid bash escaping) added an explanatory comment inside the CI-polling code block:

# Use `||` rather than `if \!` — the Bash tool escapes `\!` as `\\!`, which
# prevents bash from recognizing the pipeline-negation reserved word...

Claude Code's slash-command preprocessor scans the loaded file for \!` (a prefix that means "execute the next backticked string as a shell command") regardless of markdown code fences. It found \!` inside `if \!`, consumed text through the next backtick, and ran — the Bash tool escapes ` as bash. The em-dash is not a command, so bash reported:

Error: Shell command failed for pattern "\!` — the Bash tool escapes `":
/bin/bash: line 1: —: command not found

When the preprocessor fails, the prompt body is not delivered. Every /review <N> session in this window produced the same 5-line trace — two internal queue-operation messages, the command caveat, the command invocation, the stderr — and then nothing. The model was never given instructions to follow.

Evidence

All tend-review sessions in the past hour's window ran this preprocessor and failed identically:

Run	PR	Branch	Session size	Review posted
24261252532	#224	review-runs-timeout-detection	~120 lines	✅ APPROVED (ran before #217 merged at 20:07Z)
24262024783	#225	tend-mention-dedup-review-events	5 lines	❌
24262028666	#226	hourly/review-24261599977	—	❌ (checkout failure — infra race, separate issue)
24262305841	#226	hourly/review-24261599977	5 lines	❌
24262406137	#227	raise-job-timeouts	5 lines	❌
24262970448	#228	mention-verify-paginate	5 lines	❌
24262987799	#229	tend-claude-md-workflow-update-note	5 lines	❌
24263043865	#230	raise-job-timeouts	5 lines	❌
24263117206	#231	mention-review-inline-reply-prompt	5 lines	❌
24263177723	#232	raise-job-timeouts	5 lines	❌
24263220447	#233	tend-mention-dedup-review-events	5 lines	❌

Sample JSONL from run 24262987799 (PR #229):

{"type":"queue-operation"}
{"type":"queue-operation"}
{"type":"user","content":"<local-command-caveat>..."}
{"type":"user","content":"<command-name>/review</command-name>\n<command-args>229</command-args>"}
{"type":"user","content":"<local-command-stderr>Error: Shell command failed for pattern \"\!` — the Bash tool escapes `\": [stderr]\n/bin/bash: line 1: —: command not found</local-command-stderr>"}

No assistant turn. No Skill loads. No tool calls. No review.

Confirmation via the target PRs: gh pr view <N> --json reviews returns [] for every one of PRs #225–#233. PR #224, reviewed before #217 landed, has the bot's APPROVED review.

The same preprocessor error is also visible in the tend-mention run 24261917519 when it loaded running-in-ci via the Skill tool — there the error appeared as a tool_result and the model continued working, because skill-load failures are non-fatal. Only the top-level slash-command invocation is lethal.

Gate assessment

• Evidence level: Critical (wrong outcome — reviews 100% non-functional)
• Classification: Structural (deterministic; every invocation fails the same way)
• Occurrences this run: 9 (plus 1 non-fatal skill-load collision in tend-mention)
• Historical evidence: N/A — this regression was introduced by fix(ci-runner): replace if-not polling loop with || to avoid bash escaping #217 earlier today and has no prior tracking entries
• Change type: Targeted fix (two-line comment rephrase in two files)
• Both gates: pass

Fix

Rephrase the comments in plugins/tend-ci-runner/skills/review/SKILL.md:294 and plugins/tend-ci-runner/skills/running-in-ci/SKILL.md:142 to avoid any \!` sequence. The guidance content is unchanged: "Use || rather than if-based negation; the Bash tool escapes the exclamation mark to a literal backslash-exclamation." No \! now appears adjacent to a backtick anywhere in plugins/.

grep '\!\' plugins/` after the fix returns zero matches.

Test plan

• A tend-review run on this PR completes with an assistant session longer than 5 lines and posts an actual review (self-approval blocked, but the bot must at least read the diff and comment)
• grep -r '\!\' plugins/` returns no matches
• tend-mention and tend-notifications skill loads of running-in-ci no longer show Shell command failed for pattern in tool_results

🤖 Generated with Claude Code