From 21d2bd039df268ba220c8476b4563a7d679d6ce3 Mon Sep 17 00:00:00 2001
From: Tibsfox <tibsfox@tibsfox.com>
Date: Fri, 10 Apr 2026 07:50:35 -0700
Subject: [PATCH] fix(hooks): skip read-guard advisory on Claude Code runtime
 (#2001)
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* fix(hooks): skip read-guard advisory on Claude Code runtime (#1984)

Claude Code natively enforces read-before-edit at the runtime level,
so the gsd-read-guard.js advisory is redundant — it wastes ~80 tokens
per Write/Edit call and clutters tool flow with system-reminder noise.

Add early exit when CLAUDE_SESSION_ID is set (standard Claude Code
session env var). Non-Claude runtimes (OpenCode, Gemini, etc.) that
lack native read-before-edit enforcement continue to receive the
advisory as before.

Closes #1984

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(hooks): sanitize runHook env to prevent test failures in Claude Code

The runHook() test helper now blanks CLAUDE_SESSION_ID so positive-path
tests pass even when the test suite runs inside a Claude Code session.
The new skip test passes the env var explicitly via envOverrides.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
---
 hooks/gsd-read-guard.js   |  5 +++++
 tests/read-guard.test.cjs | 20 +++++++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/hooks/gsd-read-guard.js b/hooks/gsd-read-guard.js
index d1fe3b1e8..335a372d3 100644
--- a/hooks/gsd-read-guard.js
+++ b/hooks/gsd-read-guard.js
@@ -36,6 +36,11 @@ process.stdin.on('end', () => {
       process.exit(0);
     }
 
+    // Claude Code natively enforces read-before-edit — skip the advisory (#1984)
+    if (process.env.CLAUDE_SESSION_ID) {
+      process.exit(0);
+    }
+
     const filePath = data.tool_input?.file_path || '';
     if (!filePath) {
       process.exit(0);
diff --git a/tests/read-guard.test.cjs b/tests/read-guard.test.cjs
index 92999d242..55f0df08d 100644
--- a/tests/read-guard.test.cjs
+++ b/tests/read-guard.test.cjs
@@ -26,14 +26,17 @@ const HOOK_PATH = path.join(__dirname, '..', 'hooks', 'gsd-read-guard.js');
  * Run the read guard hook with a given tool input payload.
  * Returns { exitCode, stdout, stderr }.
  */
-function runHook(payload) {
+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: '', ...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) {
@@ -221,4 +224,19 @@ describe('gsd-read-guard hook', () => {
     assert.equal(result.exitCode, 0);
     assert.equal(result.stdout, '');
   });
+
+  // ─── Claude Code runtime skip (#1984) ─────────────────────────────────
+
+  test('skips advisory on Claude Code runtime (CLAUDE_SESSION_ID set)', () => {
+    const filePath = path.join(tmpDir, 'existing.js');
+    fs.writeFileSync(filePath, 'const x = 1;\n');
+
+    const result = runHook(
+      { tool_name: 'Edit', tool_input: { file_path: filePath, old_string: 'const x = 1;', new_string: 'const x = 2;' } },
+      { CLAUDE_SESSION_ID: 'test-session-123' }
+    );
+
+    assert.equal(result.exitCode, 0);
+    assert.equal(result.stdout, '', 'should produce no output on Claude Code');
+  });
 });