Mohamed Hegazy 70c28b9c2f
security-guidance: emit schema-valid Stop-hook output (#2159) — 2.0.2 → 2.0.3
Fixes #2159. The Stop hook emits feedback via
`hookSpecificOutput: {hookEventName: "Stop", additionalContext}`, but
`Stop`/`SubagentStop` are NOT members of CC's `hookSpecificOutput`
discriminated union (coreSchemas.ts — valid members are PreToolUse,
PostToolUse, UserPromptSubmit, SessionStart, etc.). So the emitted shape
violates CC's documented hook-output schema.

Impact is CC-version-dependent — important nuance, established empirically:

  - Reporter (array0224-cloud) on CLI 2.1.150 / 2.1.152: CC rejects the
    Stop feedback; the block/reason never reaches the model, so the
    auto-rewake/fix loop is lost. (Detection still runs + logs.)

  - On CLI 2.1.160 (current) the asyncRewake completion path is lenient:
    its gate is `isSyncHookJSONOutput` (hooks.ts) which is just
    `!(json.async === true)` — NOT a strict schema parse. So the invalid
    hookSpecificOutput is tolerated: metrics + rewakeSummary are still
    consumed and the model still receives the findings. I could NOT
    reproduce the rejection on 2.1.160, and BQ confirms Stop-path
    vulns_found metrics are recorded normally (~21k with-vuln fires / 3d),
    i.e. NOT dropped. (An earlier draft of this message claimed metrics
    were dropped — that was wrong; corrected after checking telemetry +
    repro'ing the old plugin on 2.1.160.)

So this is defensive schema-correctness: the plugin should emit output
that conforms to CC's documented union regardless of how strictly a given
CC version validates it. The reporter's environment validates strictly;
relying on the current version's leniency is fragile.

Fix (CC's documented asyncRewake "clean pattern" — hooks.ts: "error text
on stderr, JSON on stdout"):
  - For Stop/SubagentStop, emit_metrics writes guidance to stderr (the
    asyncRewake body channel CC delivers via `stderr || stdout`) and sets
    top-level `decision: "block"` + `reason` (valid SyncHookJSONOutput
    fields; also the documented sync Stop-hook contract for the `-p`
    fallback). It does NOT emit a Stop hookSpecificOutput.
  - PostToolUse (commit-review, push-sweep) is unchanged — valid union
    member, keeps the modern hookSpecificOutput protocol.

Verified locally on macOS Python 3.13:

  - py_compile clean.
  - 11 new tests (test_2159_stop_hook_schema.py) pin the contract: Stop
    output carries no hookSpecificOutput, uses top-level decision/reason,
    writes guidance to stderr; the emitted hookEventName (when present) is
    a valid union member. 2 existing tests that asserted the buggy
    Stop->hookSpecificOutput shape were corrected. Full suite 464/464
    pass + 2 skipped.

  - END-TO-END in /tmux on CLI 2.1.160:
    * FIXED plugin (2.0.3): staged pickle.loads + os.system, benign edit
      pulls the file into review_set; Stop LLM review found 2 critical
      vulns; CC delivered a clean rewake ("Background security review
      found issues" + both findings). All hooks (UPS, PostToolUse[Edit]
      pattern, PostToolUse[Bash] commit-review, Stop) fired clean; zero
      schema rejections / errors / http_err in the debug log.
    * OLD plugin (2.0.2) on the SAME 2.1.160: also delivered Stop feedback
      (confirming the no-repro-on-latest finding above) — which proves the
      fix carries NO regression risk on current CC while making the output
      robust for the stricter versions where it actually breaks.

Version bumped 2.0.2 -> 2.0.3 per the per-PR-bump policy (#2114: a bump is
the only way the fix reaches the existing fleet — relevant for users still
on the CC versions where this breaks).

Closes #2159.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-06-02 11:30:11 -07:00

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{
"name": "security-guidance",
"version": "2.0.3",
"description": "Security review for Claude-generated code. Pattern-based warnings on edits, LLM-powered diff review on Stop, and an agentic commit reviewer that catches injection, XSS, SSRF, hardcoded secrets, and 25+ other vulnerability classes.",
"author": {
"name": "David Dworken",
"email": "dworken@anthropic.com"
},
"homepage": "https://github.com/anthropics/claude-plugins-official/tree/main/plugins/security-guidance"
}