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fix(hooks): detect Claude Code via stdin session_id (closes #2520) (#2521)

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* fix(hooks): detect Claude Code via stdin session_id, not filtered env (#2520)

The #2344 fix assumed `CLAUDECODE` would propagate to hook subprocesses.
On Claude Code v2.1.116 it doesn't — Claude Code applies a separate env
filter to PreToolUse hook commands that drops bare CLAUDECODE and
CLAUDE_SESSION_ID, keeping only CLAUDE_CODE_*-prefixed vars plus
CLAUDE_PROJECT_DIR. As a result every Edit/Write on an existing file
produced a redundant READ-BEFORE-EDIT advisory inside Claude Code.

Use `data.session_id` from the hook's stdin JSON as the primary Claude
Code signal (it's part of Claude Code's documented PreToolUse hook-input
schema). Keep CLAUDE_CODE_ENTRYPOINT / CLAUDE_CODE_SSE_PORT env checks
as propagation-verified fallbacks, and keep the legacy
CLAUDE_SESSION_ID / CLAUDECODE checks for back-compat and
future-proofing.

Add tests/bug-2520-read-guard-hook-subprocess-env.test.cjs, which spawns
the hook with an env mirroring the actual Claude Code hook-subprocess
filter. Extend the legacy test harnesses to also strip the
propagation-verified CLAUDE_CODE_* vars so positive-path tests keep
passing when the suite itself runs inside a Claude Code session (same
class of leak as #2370 / PR #2375, now covering the new detection
signals).

Non-Claude-host behavior (OpenCode / MiniMax) is unchanged: with no
`session_id` on stdin and no CLAUDE_CODE_* env var, the advisory still
fires.

Closes #2520

* test(2520): isolate session_id signal from env fallbacks in regression test

Per reviewer feedback (Copilot + CodeRabbit on #2521): the session_id
isolation test used the helper's default CLAUDE_CODE_ENTRYPOINT /
CLAUDE_CODE_SSE_PORT values, so the env fallback would rescue the skip
even if the primary `data.session_id` check regressed. Pass an explicit
env override that clears those fallbacks, so only the stdin `session_id`
signal can trigger the skip.

Other cases (env-only fallback, negative / non-Claude host) already
override env appropriately.

---------

Co-authored-by: forfrossen <forfrossensvart@gmail.com>
This commit is contained in:
forfrossen
2026-04-22 16:41:58 +02:00
committed by GitHub
parent 9b5397a30f
commit af2dba2328
4 changed files with 164 additions and 4 deletions
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23
hooks/gsd-read-guard.js
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@@ -36,8 +36,27 @@ process.stdin.on('end', () => {
process.exit(0);
}
// Claude Code natively enforces read-before-edit — skip the advisory (#1984, #2344)
if (process.env.CLAUDE_SESSION_ID || process.env.CLAUDECODE) {
// Claude Code natively enforces read-before-edit — skip the advisory (#1984, #2344, #2520).
//
// Detection signals, in priority order:
// 1. `data.session_id` on the hook's stdin payload — part of Claude
// Code's documented PreToolUse hook-input schema, always present.
// Reliable across Claude Code versions because it's schema, not env.
// 2. `CLAUDE_CODE_ENTRYPOINT` / `CLAUDE_CODE_SSE_PORT` — env vars that
// Claude Code does propagate to hook subprocesses (verified on
// Claude Code CLI 2.1.116).
// 3. `CLAUDE_SESSION_ID` / `CLAUDECODE` — kept for back-compat and in
// case future Claude Code versions propagate them to hook
// subprocesses. On 2.1.116 they reach Bash tool subprocesses but
// not hook subprocesses, which is why checking them alone is
// insufficient (regression of #2344 fixed here as #2520).
const isClaudeCode =
(typeof data.session_id === 'string' && data.session_id.length > 0) ||
process.env.CLAUDE_CODE_ENTRYPOINT ||
process.env.CLAUDE_CODE_SSE_PORT ||
process.env.CLAUDE_SESSION_ID ||
process.env.CLAUDECODE;
if (isClaudeCode) {
process.exit(0);
}