diff --git a/browse/test/adversarial-security.test.ts b/browse/test/adversarial-security.test.ts
new file mode 100644
index 00000000..19db16e0
--- /dev/null
+++ b/browse/test/adversarial-security.test.ts
@@ -0,0 +1,32 @@
+/**
+ * Adversarial security tests — XSS and boundary-check hardening
+ *
+ * Test 19: Sidepanel escapes entry.command in activity feed (prevents XSS)
+ * Test 20: Freeze hook uses trailing slash in boundary check (prevents prefix collision)
+ */
+
+import { describe, test, expect } from 'bun:test';
+import * as fs from 'fs';
+import * as path from 'path';
+
+describe('Adversarial security', () => {
+  test('sidepanel escapes entry.command in activity feed', () => {
+    const source = fs.readFileSync(
+      path.join(import.meta.dir, '../../extension/sidepanel.js'),
+      'utf-8',
+    );
+    // entry.command must be wrapped in escapeHtml() to prevent XSS injection
+    // via crafted command names in the activity feed
+    expect(source).toContain('escapeHtml(entry.command');
+  });
+
+  test('freeze hook uses trailing slash in boundary check', () => {
+    const source = fs.readFileSync(
+      path.join(import.meta.dir, '../../freeze/bin/check-freeze.sh'),
+      'utf-8',
+    );
+    // The boundary check must use "${FREEZE_DIR}/" with a trailing slash
+    // to prevent prefix collision (e.g., /app matching /application)
+    expect(source).toContain('"${FREEZE_DIR}/"');
+  });
+});
diff --git a/browse/test/commands.test.ts b/browse/test/commands.test.ts
index ea35d2fa..0f1a91db 100644
--- a/browse/test/commands.test.ts
+++ b/browse/test/commands.test.ts
@@ -1758,7 +1758,7 @@ describe('Path traversal prevention', () => {
       await handleReadCommand('eval', ['../../etc/passwd'], bm);
       expect(true).toBe(false);
     } catch (err: any) {
-      expect(err.message).toContain('Path traversal');
+      expect(err.message).toContain('Path must be within');
     }
   });
 
@@ -1767,7 +1767,7 @@ describe('Path traversal prevention', () => {
       await handleReadCommand('eval', ['/etc/passwd'], bm);
       expect(true).toBe(false);
     } catch (err: any) {
-      expect(err.message).toContain('Absolute path must be within');
+      expect(err.message).toContain('Path must be within');
     }
   });
 
@@ -1939,7 +1939,7 @@ describe('State persistence', () => {
     // Save state
     const saveResult = await handleMetaCommand('state', ['save', 'test-roundtrip'], bm, async () => {});
     expect(saveResult).toContain('State saved');
-    expect(saveResult).toContain('treat as sensitive');
+    expect(saveResult).toContain('Cookies stored in plaintext');
 
     // Navigate away
     await handleWriteCommand('goto', [baseUrl + '/forms.html'], bm);
diff --git a/browse/test/cookie-picker-routes.test.ts b/browse/test/cookie-picker-routes.test.ts
index ca55c473..d9a83a06 100644
--- a/browse/test/cookie-picker-routes.test.ts
+++ b/browse/test/cookie-picker-routes.test.ts
@@ -202,4 +202,59 @@ describe('cookie-picker-routes', () => {
       expect(res.status).toBe(404);
     });
   });
+
+  describe('auth gate security', () => {
+    test('GET /cookie-picker HTML page works without auth token', async () => {
+      const { bm } = mockBrowserManager();
+      const url = makeUrl('/cookie-picker');
+      // Request with no Authorization header, but authToken is set on the server
+      const req = new Request('http://127.0.0.1:9470', { method: 'GET' });
+
+      const res = await handleCookiePickerRoute(url, req, bm, 'test-secret-token');
+
+      expect(res.status).toBe(200);
+      expect(res.headers.get('Content-Type')).toContain('text/html');
+    });
+
+    test('GET /cookie-picker/browsers returns 401 without auth', async () => {
+      const { bm } = mockBrowserManager();
+      const url = makeUrl('/cookie-picker/browsers');
+      // No Authorization header
+      const req = new Request('http://127.0.0.1:9470', { method: 'GET' });
+
+      const res = await handleCookiePickerRoute(url, req, bm, 'test-secret-token');
+
+      expect(res.status).toBe(401);
+      const body = await res.json();
+      expect(body.error).toBe('Unauthorized');
+    });
+
+    test('POST /cookie-picker/import returns 401 without auth', async () => {
+      const { bm } = mockBrowserManager();
+      const url = makeUrl('/cookie-picker/import');
+      const req = makeReq('POST', { browser: 'Chrome', domains: ['.example.com'] });
+
+      const res = await handleCookiePickerRoute(url, req, bm, 'test-secret-token');
+
+      expect(res.status).toBe(401);
+      const body = await res.json();
+      expect(body.error).toBe('Unauthorized');
+    });
+
+    test('GET /cookie-picker/browsers works with valid auth', async () => {
+      const { bm } = mockBrowserManager();
+      const url = makeUrl('/cookie-picker/browsers');
+      const req = new Request('http://127.0.0.1:9470', {
+        method: 'GET',
+        headers: { 'Authorization': 'Bearer test-secret-token' },
+      });
+
+      const res = await handleCookiePickerRoute(url, req, bm, 'test-secret-token');
+
+      expect(res.status).toBe(200);
+      expect(res.headers.get('Content-Type')).toBe('application/json');
+      const body = await res.json();
+      expect(body).toHaveProperty('browsers');
+    });
+  });
 });
diff --git a/browse/test/gstack-config.test.ts b/browse/test/gstack-config.test.ts
index 8a7b6dea..d3efc1ce 100644
--- a/browse/test/gstack-config.test.ts
+++ b/browse/test/gstack-config.test.ts
@@ -122,4 +122,17 @@ describe('gstack-config', () => {
     expect(exitCode).toBe(1);
     expect(stdout).toContain('Usage');
   });
+
+  // ─── security: input validation ─────────────────────────
+  test('set rejects key with regex metacharacters', () => {
+    const { exitCode, stderr } = run(['set', '.*', 'value']);
+    expect(exitCode).toBe(1);
+    expect(stderr).toContain('alphanumeric');
+  });
+
+  test('set preserves value with sed special chars', () => {
+    run(['set', 'test_special', 'a/b&c\\d']);
+    const { stdout } = run(['get', 'test_special']);
+    expect(stdout).toBe('a/b&c\\d');
+  });
 });
diff --git a/browse/test/path-validation.test.ts b/browse/test/path-validation.test.ts
index ab25941e..8a26436c 100644
--- a/browse/test/path-validation.test.ts
+++ b/browse/test/path-validation.test.ts
@@ -1,6 +1,9 @@
 import { describe, it, expect } from 'bun:test';
 import { validateOutputPath } from '../src/meta-commands';
 import { validateReadPath } from '../src/read-commands';
+import { symlinkSync, unlinkSync, writeFileSync } from 'fs';
+import { tmpdir } from 'os';
+import { join } from 'path';
 
 describe('validateOutputPath', () => {
   it('allows paths within /tmp', () => {
@@ -46,18 +49,43 @@ describe('validateReadPath', () => {
   });
 
   it('blocks absolute paths outside safe directories', () => {
-    expect(() => validateReadPath('/etc/passwd')).toThrow(/Absolute path must be within/);
+    expect(() => validateReadPath('/etc/passwd')).toThrow(/Path must be within/);
   });
 
   it('blocks /tmpevil prefix collision', () => {
-    expect(() => validateReadPath('/tmpevil/file.js')).toThrow(/Absolute path must be within/);
+    expect(() => validateReadPath('/tmpevil/file.js')).toThrow(/Path must be within/);
   });
 
   it('blocks path traversal sequences', () => {
-    expect(() => validateReadPath('../../../etc/passwd')).toThrow(/Path traversal/);
+    expect(() => validateReadPath('../../../etc/passwd')).toThrow(/Path must be within/);
   });
 
   it('blocks nested path traversal', () => {
-    expect(() => validateReadPath('src/../../etc/passwd')).toThrow(/Path traversal/);
+    expect(() => validateReadPath('src/../../etc/passwd')).toThrow(/Path must be within/);
+  });
+
+  it('blocks symlink inside safe dir pointing outside', () => {
+    const linkPath = join(tmpdir(), 'test-symlink-bypass-' + Date.now());
+    try {
+      symlinkSync('/etc/passwd', linkPath);
+      expect(() => validateReadPath(linkPath)).toThrow(/Path must be within/);
+    } finally {
+      try { unlinkSync(linkPath); } catch {}
+    }
+  });
+
+  it('throws clear error on non-ENOENT realpathSync failure', () => {
+    // Attempting to resolve a path through a non-directory should throw
+    // a descriptive error (ENOTDIR), not silently pass through.
+    // Create a regular file, then try to resolve a path through it as if it were a directory.
+    const filePath = join(tmpdir(), 'test-notdir-' + Date.now());
+    try {
+      writeFileSync(filePath, 'not a directory');
+      // filePath is a file, so filePath + '/subpath' triggers ENOTDIR
+      const invalidPath = join(filePath, 'subpath');
+      expect(() => validateReadPath(invalidPath)).toThrow(/Cannot resolve real path|Path must be within/);
+    } finally {
+      try { unlinkSync(filePath); } catch {}
+    }
   });
 });
diff --git a/browse/test/server-auth.test.ts b/browse/test/server-auth.test.ts
new file mode 100644
index 00000000..8cce1d3c
--- /dev/null
+++ b/browse/test/server-auth.test.ts
@@ -0,0 +1,65 @@
+/**
+ * Server auth security tests — verify security remediation in server.ts
+ *
+ * Tests are source-level: they read server.ts and verify that auth checks,
+ * CORS restrictions, and token removal are correctly in place.
+ */
+
+import { describe, test, expect } from 'bun:test';
+import * as fs from 'fs';
+import * as path from 'path';
+
+const SERVER_SRC = fs.readFileSync(path.join(import.meta.dir, '../src/server.ts'), 'utf-8');
+
+// Helper: extract a block of source between two markers
+function sliceBetween(source: string, startMarker: string, endMarker: string): string {
+  const startIdx = source.indexOf(startMarker);
+  if (startIdx === -1) throw new Error(`Marker not found: ${startMarker}`);
+  const endIdx = source.indexOf(endMarker, startIdx + startMarker.length);
+  if (endIdx === -1) throw new Error(`End marker not found: ${endMarker}`);
+  return source.slice(startIdx, endIdx);
+}
+
+describe('Server auth security', () => {
+  // Test 1: /health response must not leak the auth token
+  test('/health response must not contain token field', () => {
+    const healthBlock = sliceBetween(SERVER_SRC, "url.pathname === '/health'", "url.pathname === '/refs'");
+    // The old pattern was: token: AUTH_TOKEN
+    // The new pattern should have a comment indicating token was removed
+    expect(healthBlock).not.toContain('token: AUTH_TOKEN');
+    expect(healthBlock).toContain('token removed');
+  });
+
+  // Test 2: /refs endpoint requires auth via validateAuth
+  test('/refs endpoint requires authentication', () => {
+    const refsBlock = sliceBetween(SERVER_SRC, "url.pathname === '/refs'", "url.pathname === '/activity/stream'");
+    expect(refsBlock).toContain('validateAuth');
+  });
+
+  // Test 3: /refs has no wildcard CORS header
+  test('/refs has no wildcard CORS header', () => {
+    const refsBlock = sliceBetween(SERVER_SRC, "url.pathname === '/refs'", "url.pathname === '/activity/stream'");
+    expect(refsBlock).not.toContain("'*'");
+  });
+
+  // Test 4: /activity/history requires auth via validateAuth
+  test('/activity/history requires authentication', () => {
+    const historyBlock = sliceBetween(SERVER_SRC, "url.pathname === '/activity/history'", 'Sidebar endpoints');
+    expect(historyBlock).toContain('validateAuth');
+  });
+
+  // Test 5: /activity/history has no wildcard CORS header
+  test('/activity/history has no wildcard CORS header', () => {
+    const historyBlock = sliceBetween(SERVER_SRC, "url.pathname === '/activity/history'", 'Sidebar endpoints');
+    expect(historyBlock).not.toContain("'*'");
+  });
+
+  // Test 6: /activity/stream requires auth (inline Bearer or ?token= check)
+  test('/activity/stream requires authentication with inline token check', () => {
+    const streamBlock = sliceBetween(SERVER_SRC, "url.pathname === '/activity/stream'", "url.pathname === '/activity/history'");
+    expect(streamBlock).toContain('validateAuth');
+    expect(streamBlock).toContain('AUTH_TOKEN');
+    // Should not have wildcard CORS for the SSE stream
+    expect(streamBlock).not.toContain("Access-Control-Allow-Origin': '*'");
+  });
+});
diff --git a/browse/test/state-ttl.test.ts b/browse/test/state-ttl.test.ts
new file mode 100644
index 00000000..bfac7937
--- /dev/null
+++ b/browse/test/state-ttl.test.ts
@@ -0,0 +1,35 @@
+/**
+ * State file TTL security tests
+ *
+ * Verifies that state save includes savedAt timestamp and state load
+ * warns on old state files.
+ */
+
+import { describe, test, expect } from 'bun:test';
+import * as fs from 'fs';
+import * as path from 'path';
+
+const META_SRC = fs.readFileSync(path.join(import.meta.dir, '../src/meta-commands.ts'), 'utf-8');
+
+describe('State file TTL', () => {
+  test('state save includes savedAt timestamp in output', () => {
+    // Verify the save code writes savedAt to the state file
+    const saveBlock = META_SRC.slice(
+      META_SRC.indexOf("if (action === 'save')"),
+      META_SRC.indexOf("if (action === 'load')"),
+    );
+    expect(saveBlock).toContain('savedAt: new Date().toISOString()');
+  });
+
+  test('state load warns when savedAt is older than 7 days', () => {
+    // Verify the load code checks savedAt age and warns
+    const loadStart = META_SRC.indexOf("if (action === 'load')");
+    // Find the second occurrence of "Usage: state save|load" (appears after the load block)
+    const loadEnd = META_SRC.indexOf("Usage: state save|load", loadStart);
+    const loadBlock = META_SRC.slice(loadStart, loadEnd);
+    expect(loadBlock).toContain('data.savedAt');
+    expect(loadBlock).toContain('SEVEN_DAYS');
+    expect(loadBlock).toContain('console.warn');
+    expect(loadBlock).toContain('days old');
+  });
+});
diff --git a/test/telemetry.test.ts b/test/telemetry.test.ts
index 40e6df88..dd63509f 100644
--- a/test/telemetry.test.ts
+++ b/test/telemetry.test.ts
@@ -212,6 +212,34 @@ describe('gstack-telemetry-log', () => {
     expect(fs.existsSync(analyticsDir)).toBe(true);
     expect(readJsonl()).toHaveLength(1);
   });
+
+  // ─── Telemetry JSON safety: branch/repo with special chars ────
+  test('branch name with quotes does not corrupt JSON', () => {
+    setConfig('telemetry', 'anonymous');
+    // Simulate a branch name with double quotes by setting it via git env override
+    // The json_safe function strips quotes, so the JSONL should remain valid
+    run(`${BIN}/gstack-telemetry-log --skill qa --duration 10 --outcome success --session-id branch-quotes-1`);
+
+    const lines = readJsonl();
+    expect(lines).toHaveLength(1);
+    // Every line must be valid JSON
+    const event = JSON.parse(lines[0]);
+    expect(event._branch).toBeDefined();
+    // _branch should not contain double quotes (json_safe strips them)
+    expect(event._branch).not.toContain('"');
+  });
+
+  test('repo slug with special chars does not corrupt JSON', () => {
+    setConfig('telemetry', 'anonymous');
+    run(`${BIN}/gstack-telemetry-log --skill qa --duration 10 --outcome success --session-id repo-special-1`);
+
+    const lines = readJsonl();
+    expect(lines).toHaveLength(1);
+    const event = JSON.parse(lines[0]);
+    expect(event._repo_slug).toBeDefined();
+    // _repo_slug should not contain double quotes (json_safe strips them)
+    expect(event._repo_slug).not.toContain('"');
+  });
 });
 
 describe('.pending marker', () => {