Security: redact sensitive values from command output

Prevent secrets and sensitive data from leaking into stdout and model
transcripts by redacting output from type, cookie, header, forms, and
storage commands.

Fixes #18

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

browse/src/read-commands.ts

@@ -65,7 +65,7 @@ export async function handleReadCommand(
               id: input.id || undefined,
               placeholder: input.placeholder || undefined,
               required: input.required || undefined,
-              value: input.value || undefined,
+              value: input.type === 'password' ? '[redacted]' : (input.value || undefined),
               options: el.tagName === 'SELECT'
                 ? [...(el as HTMLSelectElement).options].map(o => ({ value: o.value, text: o.text }))
                 : undefined,
@@ -184,7 +184,7 @@ export async function handleReadCommand(
         const key = args[1];
         const value = args[2] || '';
         await page.evaluate(([k, v]) => localStorage.setItem(k, v), [key, value]);
-        return `Set localStorage["${key}"] = "${value}"`;
+        return `Set localStorage["${key}"]`;
       }
       const storage = await page.evaluate(() => ({
         localStorage: { ...localStorage },

browse/src/write-commands.ts

@@ -94,7 +94,7 @@ export async function handleWriteCommand(
       const text = args.join(' ');
       if (!text) throw new Error('Usage: browse type <text>');
       await page.keyboard.type(text);
-      return `Typed "${text}"`;
+      return `Typed ${text.length} characters`;
     }
 
     case 'press': {
@@ -153,7 +153,7 @@ export async function handleWriteCommand(
         domain: url.hostname,
         path: '/',
       }]);
-      return `Cookie set: ${name}=${value}`;
+      return `Cookie set: ${name}=****`;
     }
 
     case 'header': {
@@ -163,7 +163,9 @@ export async function handleWriteCommand(
       const name = headerStr.slice(0, sep).trim();
       const value = headerStr.slice(sep + 1).trim();
       await bm.setExtraHeader(name, value);
-      return `Header set: ${name}: ${value}`;
+      const sensitiveHeaders = ['authorization', 'cookie', 'set-cookie', 'x-api-key', 'x-auth-token'];
+      const redactedValue = sensitiveHeaders.includes(name.toLowerCase()) ? '****' : value;
+      return `Header set: ${name}: ${redactedValue}`;
     }
 
     case 'useragent': {