diff --git a/README.md b/README.md
index f00dd02..7743cfe 100644
--- a/README.md
+++ b/README.md
@@ -749,6 +749,17 @@ pairing:
 | `/pair list` | List pending codes and approved senders |
 | `/pair revoke <channel> <id>` | Revoke an approved sender |
 
+## WhatsApp Chromium Sandbox
+
+WhatsApp adapter now launches Chromium in sandboxed mode by default.
+
+If you must disable Chromium sandboxing in a high-trust/containerized environment:
+
+```yaml
+whatsapp:
+  no_sandbox: true
+```
+
 ### Gateway API
 
 | Method | Description |
diff --git a/docs/plans/analysis/2026-02-16-codebase-audit-report.md b/docs/plans/analysis/2026-02-16-codebase-audit-report.md
index 8502ad0..f8b9e2d 100644
--- a/docs/plans/analysis/2026-02-16-codebase-audit-report.md
+++ b/docs/plans/analysis/2026-02-16-codebase-audit-report.md
@@ -13,6 +13,7 @@ Scope: Production-risk-first audit of bugs, code improvements, and feature oppor
 - ✅ F-010 addressed: `session.compact` audit events now emit actual message counts for `messages_before/messages_after` (tokens remain in token fields).
 - ✅ F-012 addressed: synthetic repeated-tool nudge no longer emits invalid `tool_result.tool_use_id`; nudge is injected as plain user text guidance.
 - ✅ F-009 addressed: gateway now enforces per-connection WebSocket ingress rate limits with deterministic throttle errors and close-on-repeated-violation behavior.
+- ✅ F-008 addressed: WhatsApp Chromium launch is now sandboxed by default; no-sandbox mode is behind explicit `whatsapp.no_sandbox: true` opt-in.
 
 ## Executive Summary
 
diff --git a/docs/plans/state.json b/docs/plans/state.json
index f28ffe2..e43a965 100644
--- a/docs/plans/state.json
+++ b/docs/plans/state.json
@@ -2496,6 +2496,22 @@
         "docs/plans/analysis/2026-02-16-codebase-audit-report.md"
       ],
       "test_status": "pnpm test:run src/gateway/server.test.ts src/config/schema.test.ts + pnpm typecheck passing"
+    },
+    "audit-followup-whatsapp-sandbox-default": {
+      "status": "completed",
+      "date": "2026-02-16",
+      "updated": "2026-02-16",
+      "summary": "Hardened WhatsApp adapter Chromium launch defaults: sandbox enabled by default, with explicit opt-in no-sandbox mode via whatsapp.no_sandbox. Added adapter and schema regression tests.",
+      "files_modified": [
+        "src/channels/whatsapp/adapter.ts",
+        "src/channels/whatsapp/adapter.test.ts",
+        "src/config/schema.ts",
+        "src/config/schema.test.ts",
+        "src/daemon/channels.ts",
+        "README.md",
+        "docs/plans/analysis/2026-02-16-codebase-audit-report.md"
+      ],
+      "test_status": "pnpm test:run src/channels/whatsapp/adapter.test.ts src/config/schema.test.ts + pnpm typecheck passing"
     }
   },
   "overall_progress": {
diff --git a/src/channels/whatsapp/adapter.test.ts b/src/channels/whatsapp/adapter.test.ts
index 72cada4..1c15d47 100644
--- a/src/channels/whatsapp/adapter.test.ts
+++ b/src/channels/whatsapp/adapter.test.ts
@@ -564,6 +564,37 @@ describe('WhatsAppAdapter', () => {
     );
   });
 
+  it('uses sandboxed Chromium args by default', async () => {
+    const connectPromise = adapter.connect();
+    simulateEvent('ready');
+    await connectPromise;
+
+    const { Client } = await import('whatsapp-web.js');
+    expect(Client).toHaveBeenCalledWith(expect.objectContaining({
+      puppeteer: expect.objectContaining({
+        headless: true,
+        args: [],
+      }),
+    }));
+  });
+
+  it('allows opting into no-sandbox Chromium args via config', async () => {
+    const adapterNoSandbox = new WhatsAppAdapter({
+      allowNoSandbox: true,
+    });
+
+    const connectPromise = adapterNoSandbox.connect();
+    simulateEvent('ready');
+    await connectPromise;
+
+    const { Client } = await import('whatsapp-web.js');
+    expect(Client).toHaveBeenCalledWith(expect.objectContaining({
+      puppeteer: expect.objectContaining({
+        args: ['--no-sandbox', '--disable-setuid-sandbox'],
+      }),
+    }));
+  });
+
   it('connect sets error status when initialize() rejects', async () => {
     mockInitialize.mockRejectedValueOnce(new Error('Browser launch failed'));
 
diff --git a/src/channels/whatsapp/adapter.ts b/src/channels/whatsapp/adapter.ts
index 1d70984..2a8a97a 100644
--- a/src/channels/whatsapp/adapter.ts
+++ b/src/channels/whatsapp/adapter.ts
@@ -32,6 +32,8 @@ export interface WhatsAppAdapterConfig {
   dataDir?: string;
   /** Optional pairing manager for DM pairing codes. */
   pairingManager?: PairingManager;
+  /** Allow launching Chromium without sandbox (unsafe; use only in high-trust/containerized setups). */
+  allowNoSandbox?: boolean;
 }
 
 /** Minimal shape of a whatsapp-web.js message. */
@@ -88,11 +90,18 @@ export class WhatsAppAdapter implements ChannelAdapter {
         dataPath: this.config.dataDir,
       });
 
+      const puppeteerArgs = this.config.allowNoSandbox
+        ? ['--no-sandbox', '--disable-setuid-sandbox']
+        : [];
+      if (this.config.allowNoSandbox) {
+        console.warn('WhatsApp adapter: Chromium sandbox disabled via config (unsafe).');
+      }
+
       this.client = new Client({
         authStrategy,
         puppeteer: {
           headless: true,
-          args: ['--no-sandbox', '--disable-setuid-sandbox'],
+          args: puppeteerArgs,
         },
       });
 
diff --git a/src/config/schema.test.ts b/src/config/schema.test.ts
index 547f408..ec637a8 100644
--- a/src/config/schema.test.ts
+++ b/src/config/schema.test.ts
@@ -288,6 +288,29 @@ describe('configSchema — matrix', () => {
   });
 });
 
+describe('configSchema — whatsapp', () => {
+  const minimalConfig = {
+    telegram: { bot_token: 'test', allowed_chat_ids: [1] },
+    models: { default: { provider: 'anthropic', model: 'claude-3' } },
+  };
+
+  it('defaults whatsapp no_sandbox to false', () => {
+    const result = configSchema.parse({
+      ...minimalConfig,
+      whatsapp: {},
+    });
+    expect(result.whatsapp?.no_sandbox).toBe(false);
+  });
+
+  it('accepts whatsapp no_sandbox override', () => {
+    const result = configSchema.parse({
+      ...minimalConfig,
+      whatsapp: { no_sandbox: true },
+    });
+    expect(result.whatsapp?.no_sandbox).toBe(true);
+  });
+});
+
 describe('configSchema — skills watcher', () => {
   const minimalConfig = {
     telegram: { bot_token: 'test', allowed_chat_ids: [1] },
diff --git a/src/config/schema.ts b/src/config/schema.ts
index 9683ed3..32aea49 100644
--- a/src/config/schema.ts
+++ b/src/config/schema.ts
@@ -373,6 +373,7 @@ const whatsappSchema = z.object({
   allowed_group_ids: z.array(z.string()).default([]),
   require_mention: z.boolean().default(true),
   data_dir: z.string().optional(),
+  no_sandbox: z.boolean().default(false),
 }).optional();
 
 const matrixSchema = z.object({
diff --git a/src/daemon/channels.ts b/src/daemon/channels.ts
index 7488e8e..46d4e4a 100644
--- a/src/daemon/channels.ts
+++ b/src/daemon/channels.ts
@@ -66,6 +66,7 @@ export function registerChannels(deps: ChannelsDeps): ChannelsResult {
       requireMention: config.whatsapp.require_mention,
       dataDir: config.whatsapp.data_dir,
       pairingManager,
+      allowNoSandbox: config.whatsapp.no_sandbox,
     });
     channelRegistry.register(whatsappAdapter);
   }