feat: add Prettier formatting hook for file edits

.claude/hooks/prettier-format.js

@@ -0,0 +1,36 @@
+#!/usr/bin/env node
+// PostToolUse hook (Write|Edit): formats the touched file with the repo's local Prettier.
+const fs = require('fs');
+const path = require('path');
+const { execFileSync } = require('child_process');
+
+let raw = '';
+try {
+  raw = fs.readFileSync(0, 'utf8');
+} catch {
+  process.exit(0);
+}
+
+let input;
+try {
+  input = JSON.parse(raw);
+} catch {
+  process.exit(0);
+}
+
+const filePath = input.tool_response?.filePath || input.tool_input?.file_path;
+if (!filePath || !fs.existsSync(filePath)) {
+  process.exit(0);
+}
+
+const repoRoot = path.join(__dirname, '..', '..');
+const prettierCli = path.join(repoRoot, 'node_modules', 'prettier', 'bin', 'prettier.cjs');
+
+try {
+  execFileSync(process.execPath, [prettierCli, '--ignore-unknown', '--write', filePath], {
+    cwd: repoRoot,
+    stdio: 'ignore',
+  });
+} catch {
+  // Ignore formatting failures (e.g. syntax errors) so the hook never blocks the agent.
+}

.claude/settings.json

@@ -5,5 +5,19 @@
       "Edit(packages/insomnia/bin/yarn-standalone.js)",
       "Write(packages/insomnia/bin/yarn-standalone.js)"
     ]
+  },
+  "hooks": {
+    "PostToolUse": [
+      {
+        "matcher": "Write|Edit",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "node .claude/hooks/prettier-format.js",
+            "timeout": 30
+          }
+        ]
+      }
+    ]
   }
 }