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

* 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

View File

@@ -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);
}

View File

@@ -29,6 +29,9 @@ function runHook(payload, envOverrides = {}) {
...process.env,
CLAUDE_SESSION_ID: '',
CLAUDECODE: '',
CLAUDE_CODE_ENTRYPOINT: '',
CLAUDE_CODE_SSE_PORT: '',
CLAUDE_PROJECT_DIR: '',
...envOverrides,
};
try {

View File

@@ -0,0 +1,129 @@
/**
* Regression test for bug #2520
*
* The fix for #2344 added `|| process.env.CLAUDECODE` to the Claude Code
* skip check. That works in principle — CLAUDECODE=1 is propagated to Bash
* tool subprocesses — but it does NOT reach hook subprocesses on Claude Code
* v2.1.116. Claude Code applies a separate env filter when spawning
* PreToolUse hook commands; that filter drops bare CLAUDECODE and
* CLAUDE_SESSION_ID and keeps only CLAUDE_CODE_*-prefixed vars plus
* CLAUDE_PROJECT_DIR. `data.session_id` is, however, reliably delivered via
* the hook's stdin JSON payload (documented part of Claude Code's hook
* input schema).
*
* Fix: use `data.session_id` as the primary Claude Code signal, with
* CLAUDE_CODE_ENTRYPOINT / CLAUDE_CODE_SSE_PORT as env-var fallbacks, and
* keep legacy CLAUDECODE / CLAUDE_SESSION_ID for back-compat and
* future-proofing.
*/
process.env.GSD_TEST_MODE = '1';
const { test, describe, beforeEach, afterEach } = require('node:test');
const assert = require('node:assert/strict');
const fs = require('node:fs');
const path = require('node:path');
const { execFileSync } = require('node:child_process');
const { createTempDir, cleanup } = require('./helpers.cjs');
const HOOK_PATH = path.join(__dirname, '..', 'hooks', 'gsd-read-guard.js');
/**
* Spawn the hook with an env that mirrors the actual Claude Code hook
* subprocess env: CLAUDECODE and CLAUDE_SESSION_ID are stripped, only
* CLAUDE_CODE_*-prefixed vars (plus CLAUDE_PROJECT_DIR) remain. Extra env
* overrides can be supplied via `envOverrides`.
*/
function runHookInClaudeCodeSubprocess(payload, envOverrides = {}) {
const input = JSON.stringify(payload);
const baseEnv = { ...process.env };
// Strip env vars Claude Code does NOT propagate to hook subprocesses.
delete baseEnv.CLAUDECODE;
delete baseEnv.CLAUDE_SESSION_ID;
const env = {
...baseEnv,
// Env vars Claude Code DOES propagate to hook subprocesses (observed on
// Claude Code CLI 2.1.116).
CLAUDE_CODE_ENTRYPOINT: 'cli',
CLAUDE_CODE_SSE_PORT: '51291',
CLAUDE_PROJECT_DIR: process.cwd(),
...envOverrides,
};
try {
const stdout = execFileSync(process.execPath, [HOOK_PATH], {
input,
encoding: 'utf-8',
timeout: 5000,
stdio: ['pipe', 'pipe', 'pipe'],
env,
});
return { exitCode: 0, stdout: stdout.trim(), stderr: '' };
} catch (err) {
return {
exitCode: err.status ?? 1,
stdout: (err.stdout || '').toString().trim(),
stderr: (err.stderr || '').toString().trim(),
};
}
}
describe('bug #2520: read guard detects Claude Code without relying on CLAUDECODE env', () => {
let tmpDir;
beforeEach(() => { tmpDir = createTempDir('gsd-read-guard-2520-'); });
afterEach(() => { cleanup(tmpDir); });
test('skips advisory when stdin payload includes session_id (Claude Code hook-subprocess env)', () => {
const filePath = path.join(tmpDir, 'existing.js');
fs.writeFileSync(filePath, 'const x = 1;\n');
// Isolate the stdin `session_id` signal by clearing the CLAUDE_CODE_*
// env fallbacks the helper normally provides. Without this the env
// fallback would rescue the skip even if session_id detection broke,
// hiding a regression of the primary signal.
const result = runHookInClaudeCodeSubprocess(
{
session_id: 'e7123e54-0977-45dd-848a-b9c8a45a5cd3',
tool_name: 'Edit',
tool_input: { file_path: filePath, old_string: 'const x = 1;', new_string: 'const x = 2;' },
},
{ CLAUDE_CODE_ENTRYPOINT: '', CLAUDE_CODE_SSE_PORT: '', CLAUDE_PROJECT_DIR: '' },
);
assert.equal(result.exitCode, 0);
assert.equal(
result.stdout,
'',
'advisory must not fire when session_id is present on stdin (real Claude Code hook env)',
);
});
test('skips advisory when CLAUDE_CODE_ENTRYPOINT is set (env-var fallback, no session_id on stdin)', () => {
const filePath = path.join(tmpDir, 'existing.js');
fs.writeFileSync(filePath, 'const x = 1;\n');
const result = runHookInClaudeCodeSubprocess(
{ tool_name: 'Edit', tool_input: { file_path: filePath, old_string: 'const x = 1;', new_string: 'const x = 2;' } },
{ CLAUDE_CODE_ENTRYPOINT: 'cli', CLAUDE_CODE_SSE_PORT: '' },
);
assert.equal(result.exitCode, 0);
assert.equal(result.stdout, '', 'advisory must not fire when CLAUDE_CODE_ENTRYPOINT is set');
});
test('still injects advisory when no Claude Code signal is present (non-Claude host)', () => {
const filePath = path.join(tmpDir, 'existing.js');
fs.writeFileSync(filePath, 'const x = 1;\n');
const result = runHookInClaudeCodeSubprocess(
{ tool_name: 'Edit', tool_input: { file_path: filePath, old_string: 'const x = 1;', new_string: 'const x = 2;' } },
{ CLAUDE_CODE_ENTRYPOINT: '', CLAUDE_CODE_SSE_PORT: '', CLAUDE_PROJECT_DIR: '' },
);
assert.equal(result.exitCode, 0);
assert.ok(result.stdout.length > 0, 'advisory should fire on non-Claude-Code hosts');
const output = JSON.parse(result.stdout);
assert.ok(output.hookSpecificOutput?.additionalContext?.includes('Read'));
});
});

View File

@@ -28,8 +28,17 @@ const HOOK_PATH = path.join(__dirname, '..', 'hooks', 'gsd-read-guard.js');
*/
function runHook(payload, envOverrides = {}) {
const input = JSON.stringify(payload);
// Sanitize CLAUDE_SESSION_ID so positive-path tests work inside Claude Code sessions
const env = { ...process.env, CLAUDE_SESSION_ID: '', CLAUDECODE: '', ...envOverrides };
// Sanitize all Claude Code detection signals so positive-path tests work
// when the test runner itself is running inside Claude Code (#2344, #2520).
const env = {
...process.env,
CLAUDE_SESSION_ID: '',
CLAUDECODE: '',
CLAUDE_CODE_ENTRYPOINT: '',
CLAUDE_CODE_SSE_PORT: '',
CLAUDE_PROJECT_DIR: '',
...envOverrides,
};
try {
const stdout = execFileSync(process.execPath, [HOOK_PATH], {
input,