[BUG] Hooks not saving

I wonder, the config files are symlinked. Would this cause trouble?

Because my ~/.claude/settings.json is a symlink, I tested the theory of adding the test hook to my project .claude/settings.json, because that is just a file. It still does not work after that change. Further, though I have no Stop command configured, debug apparently shows it's looking for a Stop command (but this could be that it is just being verbose, saying "you don't have a stop command"):

> [DEBUG] Executing hooks for Stop
  [DEBUG] Getting matching hook commands for Stop with query: undefined
  [DEBUG] Found 0 hook matchers in settings
  [DEBUG] No match query, returning all 0 hooks
  [DEBUG] Found 0 hook commands to execute

Also, an aside, but the language in "where should this hook be saved" could be polished up. Inconsistent labels.

<img width="2886" height="1476" alt="Image" src="https://github.com/user-attachments/assets/de5ad0df-e83d-444e-8b04-13c6ef53ccb1" />

Ok, after debugging, I discovered the hooks were configured correctly but failing silently due to missing permissions and lack of proper error handling. Here's what fixed it:

Root Cause

1. Missing write permissions - The TypeScript hook only had --allow-read but was trying to write to a log file
2. No error output - Hooks were failing silently without any visible feedback
3. Exit codes - Hooks need to use specific exit codes for Claude Code to show output

Solution

The key changes were to the TypeScript hook command and adding proper error handling:

# In .claude/settings.json (or ~/.claude/settings.json)
{
    "hooks": {
      "PreToolUse": [
        {
          "matcher": "Write|Edit|MultiEdit",
          "hooks": [
            {
              "type": "command",
-           "command": "deno run --allow-read /path/to/hook.ts"
+           "command": "deno run --allow-read --allow-write /path/to/hook.ts"
            }
          ]
        }
      ]
    }
}

And in the TypeScript hook itself, adding proper error handling and exit codes:

// aichaku-hooks.ts
#!/usr/bin/env -S deno run --allow-read --allow-write

+// Debug logging function - writes to stderr which shows with exit code 2
+function debug(message: string): void {
+  const timestamp = new Date().toISOString();
+  const logMessage = `[${timestamp}] hook: ${message}\n`;
+  Deno.stderr.writeSync(new TextEncoder().encode(logMessage));
+}

async function sensitiveFileGuard(input: HookInput): Promise<void> {
+  debug(`Checking file: ${input.tool_input?.file_path}`);
const filePath = input.tool_input?.file_path;

    if (filePath && typeof filePath === 'string') {
      const sensitivePatterns = [/\.env$/, /\.env\.\w+$/, /secrets/i];

      if (sensitivePatterns.some(pattern => pattern.test(filePath))) {
        console.log('⚠️  Modifying potentially sensitive file - proceed with caution');
-     Deno.exit(0);  // Silent exit
+     Deno.exit(2);  // Exit code 2 shows stderr to model and blocks tool
      }
    }
}

// Error handling for stdin parsing
  try {
    const input = await readInput();
    // ... process hook
  } catch (e) {
  +  console.error(`Failed to read input: ${e}`);
  +  Deno.exit(2);  // Show error and block
}

Working Example

With these changes, the hooks I was going for now work properly:

🪴 Creating .env.test file...
❌ Write operation blocked by hook:
⚠️ Modifying potentially sensitive file - proceed with caution

Key Findings

1. Exit codes matter:

• Exit 0 = silent (no output shown)
• Exit 2 = show stderr to model and block tool call
• Other codes = show stderr to user but continue

1. Permissions are critical - Always include necessary Deno permissions
2. Debug logging to stderr is essential for troubleshooting
3. Despite Anthropic website chatbot insisting you must run everything through /hooks, that's not the case, so long as you restart claude code after you make changes. You need to validate carefully, but, it does work to directly edit the config files.

In the end the hooks feature is working in Claude Code - it just needs proper configuration and error handling to be visible.

Hope this will help others who encounter similar issues with hooks not appearing to work! Sorry for the firedrill!

Thanks for writing up your setup experience!

though I have no Stop command configured, debug apparently shows it's looking for a Stop command

Yes, it's just being verbose. It indicates to the user that that moment is when the hook would trigger.

Inconsistent labels.

The inconsistency is intentional. .claude/settings.json (project-level settings) is not in .gitignore, while .claude/settings.local.json (project-local-level settings) is in .gitignore. This means that if you add a hook to .claude/settings.json and git stage/commit normally, the hooks will then be used for everyone else who checks out your commit.

Despite Anthropic website chatbot insisting you must run everything through /hooks

The documentation at https://docs.anthropic.com/en/docs/claude-code/hooks is authoritative. You can pass in the documentation into either Claude Code or claude.ai for better results. Otherwise, neither Claude Code nor claude.ai will know anything about the hooks feature.

I've passed those docs and still got back some mean hallucinations about what has to be done, but noted. I got the diff between configs, but the grammar in the screenshot is a little funky. At any rate, thanks!

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