fix(hooks): scrub secrets and harden hook security (#348)

* fix(hooks): scrub secrets and harden hook security

- Scrub common secret patterns (api_key, token, password, etc.) from
  observation logs before persisting to JSONL (observe.sh)
- Auto-purge observation files older than 30 days (observe.sh)
- Strip embedded credentials from git remote URLs before saving to
  projects.json (detect-project.sh)
- Add command prefix allowlist to runCommand — only git, node, npx,
  which, where are permitted (utils.js)
- Sanitize CLAUDE_SESSION_ID in temp file paths to prevent path
  traversal (suggest-compact.js)

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

* fix(hooks): address review feedback from CodeRabbit and Cubic

- Reject shell command-chaining operators (;|&`) in runCommand, strip
  quoted sections before checking to avoid false positives (utils.js)
- Remove command string from blocked error message to avoid leaking
  secrets (utils.js)
- Fix Python regex quoting: switch outer shell string from double to
  single quotes so regex compiles correctly (observe.sh)
- Add optional auth scheme match (Bearer, Basic) to secret scrubber
  regex (observe.sh)
- Scope auto-purge to current project dir and match only archived
  files (observations-*.jsonl), not live queue (observe.sh)
- Add second fallback after session ID sanitization to prevent empty
  string (suggest-compact.js)
- Preserve backward compatibility when credential stripping changes
  project hash — detect and migrate legacy directories
  (detect-project.sh)

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

* fix(hooks): block $() substitution, fix Bearer redaction, add security tests

- Add $ and \n to blocked shell metacharacters in runCommand to prevent
  command substitution via $(cmd) and newline injection (utils.js)
- Make auth scheme group capturing so Bearer/Basic is preserved in
  redacted output instead of being silently dropped (observe.sh)
- Add 10 unit tests covering runCommand allowlist blocking (rm, curl,
  bash prefixes) and metacharacter rejection (;|&`$ chaining), plus
  error message leak prevention (utils.test.js)

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

* fix(hooks): scrub parse-error fallback, strengthen security tests

Address remaining reviewer feedback from CodeRabbit and Cubic:

- Scrub secrets in observe.sh parse-error fallback path (was writing
  raw unsanitized input to observations file)
- Remove redundant re.IGNORECASE flag ((?i) inline flag already set)
- Add inline comment documenting quote-stripping limitation trade-off
- Fix misleading test name for error-output test
- Add 5 new security tests: single-quote passthrough, mixed
  quoted+unquoted metacharacters, prefix boundary (no trailing space),
  npx acceptance, and newline injection
- Improve existing quoted-metacharacter test to actually exercise
  quote-stripping logic

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

* fix(security): block $() and backtick inside quotes in runCommand

Shell evaluates $() and backticks inside double quotes, so checking
only the unquoted portion was insufficient. Now $ and ` are rejected
anywhere in the command string, while ; | & remain quote-aware.

Addresses CodeRabbit and Cubic review feedback on PR #348.

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

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

scripts/lib/utils.js

@@ -339,6 +339,20 @@ function commandExists(cmd) {
  * @param {object} options - execSync options
  */
 function runCommand(cmd, options = {}) {
+  // Allowlist: only permit known-safe command prefixes
+  const allowedPrefixes = ['git ', 'node ', 'npx ', 'which ', 'where '];
+  if (!allowedPrefixes.some(prefix => cmd.startsWith(prefix))) {
+    return { success: false, output: 'runCommand blocked: unrecognized command prefix' };
+  }
+
+  // Reject shell metacharacters. $() and backticks are evaluated inside
+  // double quotes, so block $ and ` anywhere in cmd. Other operators
+  // (;|&) are literal inside quotes, so only check unquoted portions.
+  const unquoted = cmd.replace(/"[^"]*"/g, '').replace(/'[^']*'/g, '');
+  if (/[;|&\n]/.test(unquoted) || /[`$]/.test(cmd)) {
+    return { success: false, output: 'runCommand blocked: shell metacharacters not allowed' };
+  }
+
   try {
     const result = execSync(cmd, {
       encoding: 'utf8',