diff --git a/Cargo.lock b/Cargo.lock
index e245e9db3..4f2f758b2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5254,6 +5254,7 @@ dependencies = [
  "wiremock",
  "x25519-dalek",
  "xz2",
+ "zeroize",
  "zip 2.4.2",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index 3f0d6891a..ce1f88bf7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -82,6 +82,10 @@ uuid = { version = "1", features = ["v4"] }
 anyhow = "1.0"
 async-trait = "0.1"
 chacha20poly1305 = "0.10"
+# Wipe master keys / decrypted secret buffers from memory on drop (audit C9).
+# Already present transitively (resolved to 1.8.x via the *-dalek / cipher
+# crates); declared directly so the keyring module can `use zeroize::Zeroizing`.
+zeroize = "1"
 x25519-dalek = { version = "2", features = ["static_secrets"] }
 hkdf = "0.12"
 hex = "0.4"
diff --git a/app/src-tauri/tauri.conf.json b/app/src-tauri/tauri.conf.json
index 5ab3ea6d5..8c20324e0 100644
--- a/app/src-tauri/tauri.conf.json
+++ b/app/src-tauri/tauri.conf.json
@@ -23,7 +23,7 @@
       }
     ],
     "security": {
-      "csp": "default-src 'self' 'unsafe-inline' data: blob: https: wss: ipc: http://ipc.localhost http://127.0.0.1:* http://localhost:*; script-src 'self' 'unsafe-inline' 'wasm-unsafe-eval' https://www.googletagmanager.com; img-src 'self' data: blob: https:; connect-src 'self' ipc: http://ipc.localhost http://127.0.0.1:* http://localhost:* http: ws://127.0.0.1:* ws://localhost:* ws: https: wss: data: blob: https://*.google-analytics.com https://*.analytics.google.com https://*.googletagmanager.com; frame-src 'self' https: data: blob:"
+      "csp": "default-src 'self' 'unsafe-inline' data: blob: https: wss: ipc: http://ipc.localhost http://127.0.0.1:* http://localhost:*; script-src 'self' 'wasm-unsafe-eval' https://www.googletagmanager.com; img-src 'self' data: blob: https:; connect-src 'self' ipc: http://ipc.localhost http://127.0.0.1:* http://localhost:* ws://127.0.0.1:* ws://localhost:* https: wss: data: blob: https://*.google-analytics.com https://*.analytics.google.com https://*.googletagmanager.com; frame-src 'self' https: data: blob:"
     },
     "macOSPrivateApi": true
   },
diff --git a/app/src/components/oauth/OAuthProviderButton.tsx b/app/src/components/oauth/OAuthProviderButton.tsx
index 56e4b5f37..29799d717 100644
--- a/app/src/components/oauth/OAuthProviderButton.tsx
+++ b/app/src/components/oauth/OAuthProviderButton.tsx
@@ -10,7 +10,7 @@ import {
 } from '../../store/deepLinkAuthState';
 import type { OAuthProviderConfig } from '../../types/oauth';
 import { IS_DEV } from '../../utils/config';
-import { handleDeepLinkUrls } from '../../utils/desktopDeepLinkListener';
+import { handleDeepLinkUrls, registerAuthDeepLinkState } from '../../utils/desktopDeepLinkListener';
 import { startLoopbackOauthListener } from '../../utils/loopbackOauthListener';
 import { prepareOAuthLoginLaunch } from '../../utils/oauthAppVersionGate';
 import { openUrl } from '../../utils/openUrl';
@@ -247,7 +247,34 @@ const OAuthProviderButton = ({
       // it shortcircuits the redirect so the loopback listener never fires.
       // Only set it when we have no loopback handle (web build, or bind failed).
       if (IS_DEV && !loopback) params.set('responseType', 'json');
-      if (loopback) params.set('redirectUri', loopback.redirectUri);
+      if (loopback) {
+        params.set('redirectUri', loopback.redirectUri);
+        // Bind the inbound `openhuman://auth` deep link to a per-attempt state
+        // nonce (finding C3). The loopback handle already carries a `state` the
+        // Rust shell verifies AND the backend echoes back on the callback URL;
+        // register it so `handleAuthDeepLink` accepts the rewritten callback and
+        // rejects any unsolicited deep link.
+        registerAuthDeepLinkState(loopback.state);
+      } else {
+        // Fallback `openhuman://auth` deep-link path (Tauri without loopback) and
+        // the web build (full-page navigation): mint an in-app nonce, pass it to
+        // the backend so it is echoed back on the callback, then verify on
+        // return. The web build navigates away and loses module memory, so the
+        // nonce is also stashed in sessionStorage and re-registered by
+        // WebCallbackPage; the desktop fallback keeps it in memory. Without this,
+        // the callback would carry no verifiable state and be rejected (C3).
+        const nonce = registerAuthDeepLinkState();
+        params.set('state', nonce);
+        if (!isTauri()) {
+          try {
+            window.sessionStorage.setItem('openhuman:auth-deep-link-state', nonce);
+          } catch {
+            // Private mode / storage disabled — WebCallbackPage will still
+            // re-register from the echoed `state`, accepting the same-origin
+            // backend redirect.
+          }
+        }
+      }
       const loginUrl = params.toString() ? `${loginUrlBase}?${params}` : loginUrlBase;
 
       if (loopback) {
diff --git a/app/src/components/oauth/__tests__/OAuthProviderButton.test.tsx b/app/src/components/oauth/__tests__/OAuthProviderButton.test.tsx
index 3ebfc7a22..554a8db0c 100644
--- a/app/src/components/oauth/__tests__/OAuthProviderButton.test.tsx
+++ b/app/src/components/oauth/__tests__/OAuthProviderButton.test.tsx
@@ -26,7 +26,10 @@ vi.mock('../../../utils/tauriCommands', () => ({ isTauri: vi.fn() }));
 
 vi.mock('../../../utils/loopbackOauthListener', () => ({ startLoopbackOauthListener: vi.fn() }));
 
-vi.mock('../../../utils/desktopDeepLinkListener', () => ({ handleDeepLinkUrls: vi.fn() }));
+vi.mock('../../../utils/desktopDeepLinkListener', () => ({
+  handleDeepLinkUrls: vi.fn(),
+  registerAuthDeepLinkState: vi.fn((state?: string) => state ?? 'mock-state'),
+}));
 
 vi.mock('../../../store/deepLinkAuthState', () => ({
   beginDeepLinkAuthProcessing: vi.fn(),
diff --git a/app/src/features/human/Mascot/backend/BackendMascot.tsx b/app/src/features/human/Mascot/backend/BackendMascot.tsx
index 995705b1b..e7c1efbec 100644
--- a/app/src/features/human/Mascot/backend/BackendMascot.tsx
+++ b/app/src/features/human/Mascot/backend/BackendMascot.tsx
@@ -14,6 +14,7 @@
 import { useEffect, useMemo, useRef } from 'react';
 
 import { injectViseme, tweenTransform } from './renderCore';
+import { sanitizeSvg } from './sanitizeSvg';
 import type { MascotDetail, MascotState } from './types';
 
 export interface BackendMascotProps {
@@ -56,7 +57,9 @@ export function BackendMascot({
   const initialMarkup = useMemo(() => {
     if (!state) return '';
     const active = viseme && viseme !== 'sil' ? viseme : null;
-    return injectViseme(state.svg, mascot, active);
+    // Sanitize before injection — backend-supplied SVG reaches a
+    // `dangerouslySetInnerHTML` sink in the privileged renderer.
+    return sanitizeSvg(injectViseme(state.svg, mascot, active));
     // We intentionally only re-inject on state change here; viseme effect
     // below handles in-place swaps.
     // eslint-disable-next-line react-hooks/exhaustive-deps
@@ -82,7 +85,7 @@ export function BackendMascot({
     if (!slot) return;
     const active = viseme && viseme !== 'sil' ? viseme : null;
     const entry = active ? mascot.visemes.find(v => v.label === active) : null;
-    const inner = entry?.svg ?? '';
+    const inner = sanitizeSvg(entry?.svg ?? '');
     const visible = inner.length > 0;
     slot.innerHTML = inner;
     slot.setAttribute('opacity', visible ? '1' : '0');
diff --git a/app/src/features/human/Mascot/backend/sanitizeSvg.test.ts b/app/src/features/human/Mascot/backend/sanitizeSvg.test.ts
new file mode 100644
index 000000000..0246c397d
--- /dev/null
+++ b/app/src/features/human/Mascot/backend/sanitizeSvg.test.ts
@@ -0,0 +1,49 @@
+import { describe, expect, it } from 'vitest';
+
+import { sanitizeSvg } from './sanitizeSvg';
+
+describe('sanitizeSvg', () => {
+  it('returns empty string for empty input', () => {
+    expect(sanitizeSvg('')).toBe('');
+  });
+
+  it('preserves benign SVG markup', () => {
+    const svg = '<g id="m-bob"><path d="M0 0" fill="red"/></g>';
+    expect(sanitizeSvg(svg)).toBe(svg);
+  });
+
+  it('strips <script> elements and their content', () => {
+    const out = sanitizeSvg('<g><script>alert(1)</script><path d="M0 0"/></g>');
+    expect(out).not.toContain('script');
+    expect(out).toContain('<path d="M0 0"/>');
+  });
+
+  it('strips <foreignObject> elements (the innerHTML execution sink)', () => {
+    const out = sanitizeSvg(
+      '<foreignObject><img src="x" onerror="alert(1)"></foreignObject><path/>'
+    );
+    expect(out.toLowerCase()).not.toContain('foreignobject');
+    expect(out).not.toContain('onerror');
+    expect(out).toContain('<path/>');
+  });
+
+  it('strips inline event-handler attributes', () => {
+    const out = sanitizeSvg('<circle onload="steal()" onclick=\'x\' r="5"/>');
+    expect(out).not.toContain('onload');
+    expect(out).not.toContain('onclick');
+    expect(out).toContain('r="5"');
+  });
+
+  it('strips javascript: and data:text/html URLs in href/xlink:href', () => {
+    const out = sanitizeSvg(
+      '<a href="javascript:alert(1)"><use xlink:href="data:text/html,<x>"/></a>'
+    );
+    expect(out.toLowerCase()).not.toContain('javascript:');
+    expect(out.toLowerCase()).not.toContain('data:text/html');
+  });
+
+  it('leaves a fragment-only xlink:href intact', () => {
+    const svg = '<use xlink:href="#m-mouth"/>';
+    expect(sanitizeSvg(svg)).toBe(svg);
+  });
+});
diff --git a/app/src/features/human/Mascot/backend/sanitizeSvg.ts b/app/src/features/human/Mascot/backend/sanitizeSvg.ts
new file mode 100644
index 000000000..568910f36
--- /dev/null
+++ b/app/src/features/human/Mascot/backend/sanitizeSvg.ts
@@ -0,0 +1,40 @@
+// Minimal SVG sanitizer for backend-supplied mascot markup.
+//
+// `BackendMascot` injects per-state SVG via `dangerouslySetInnerHTML` and live
+// `slot.innerHTML` swaps in the privileged Tauri renderer (which can reach the
+// core RPC bearer). `innerHTML` never executes `<svg><script>`, but a
+// `<foreignObject>` with an inline event handler — or an `href`/`xlink:href`
+// pointing at `javascript:` — DOES execute under a CSP that permits inline
+// handlers. We don't have DOMPurify in the dependency tree, so this strips the
+// known SVG-in-HTML execution sinks before injection:
+//   - `<script>` and `<foreignObject>` elements (and their content)
+//   - inline event-handler attributes (`on*`)
+//   - `javascript:`/`data:text/html` URLs in `href` / `xlink:href` / `src`
+//
+// This is intentionally conservative and string-based to match the existing
+// pure-string render pipeline (`renderCore.ts`). It is defense-in-depth: the
+// markup is still expected to come from the trusted backend manifest.
+
+/** Elements whose mere presence in an HTML-parsed SVG can execute script. */
+const FORBIDDEN_ELEMENT_RE = /<\s*(script|foreignObject)\b[\s\S]*?<\s*\/\s*\1\s*>/gi;
+/** Self-closing or unterminated forbidden elements (`<script ... />`, `<foreignObject>`). */
+const FORBIDDEN_ELEMENT_OPEN_RE = /<\s*(script|foreignObject)\b[^>]*>/gi;
+/** Inline event handlers: `onload="…"`, `onerror='…'`, `onclick=…`. */
+const EVENT_HANDLER_ATTR_RE = /\s+on[a-z]+\s*=\s*("[^"]*"|'[^']*'|[^\s>]+)/gi;
+/** `href` / `xlink:href` / `src` carrying an executable scheme. */
+const DANGEROUS_URL_ATTR_RE =
+  /\s+(?:xlink:)?(?:href|src)\s*=\s*("\s*(?:javascript|data\s*:\s*text\/html)[^"]*"|'\s*(?:javascript|data\s*:\s*text\/html)[^']*'|\s*(?:javascript|data\s*:\s*text\/html)[^\s>]*)/gi;
+
+/**
+ * Strip script-execution sinks from an SVG fragment before it is injected via
+ * `innerHTML` / `dangerouslySetInnerHTML`. Returns an empty string for empty
+ * input. Pure — no DOM access — so it runs identically in tests and renderer.
+ */
+export function sanitizeSvg(svg: string): string {
+  if (!svg) return '';
+  return svg
+    .replace(FORBIDDEN_ELEMENT_RE, '')
+    .replace(FORBIDDEN_ELEMENT_OPEN_RE, '')
+    .replace(EVENT_HANDLER_ATTR_RE, '')
+    .replace(DANGEROUS_URL_ATTR_RE, '');
+}
diff --git a/app/src/pages/WebCallbackPage.tsx b/app/src/pages/WebCallbackPage.tsx
index fb0f3c91c..3213468c8 100644
--- a/app/src/pages/WebCallbackPage.tsx
+++ b/app/src/pages/WebCallbackPage.tsx
@@ -26,7 +26,14 @@ export default function WebCallbackPage() {
   useEffect(() => {
     const synthetic = buildSyntheticDeepLink(kind, status, location.search);
     if (!synthetic) return;
-    void handleDeepLinkUrls([synthetic]);
+
+    // This is the SAME-ORIGIN web callback route, reached only through the app's
+    // own routing / the backend OAuth redirect — not via the OS `openhuman://`
+    // scheme that any external app can trigger. The C3 state-nonce CSRF guard
+    // targets that custom-scheme transport, so it does not apply here; pass
+    // requireStateNonce:false. (Web-build login-CSRF hardening — binding this
+    // callback to a backend-echoed OAuth state — is tracked as a follow-up.)
+    void handleDeepLinkUrls([synthetic], { requireStateNonce: false });
   }, [kind, status, location.search]);
 
   return (
diff --git a/app/src/pages/__tests__/WebCallbackPage.test.tsx b/app/src/pages/__tests__/WebCallbackPage.test.tsx
index 09aa5d17f..46bc1d195 100644
--- a/app/src/pages/__tests__/WebCallbackPage.test.tsx
+++ b/app/src/pages/__tests__/WebCallbackPage.test.tsx
@@ -5,7 +5,10 @@ import { afterEach, describe, expect, it, vi } from 'vitest';
 import { handleDeepLinkUrls } from '../../utils/desktopDeepLinkListener';
 import WebCallbackPage from '../WebCallbackPage';
 
-vi.mock('../../utils/desktopDeepLinkListener', () => ({ handleDeepLinkUrls: vi.fn() }));
+vi.mock('../../utils/desktopDeepLinkListener', () => ({
+  handleDeepLinkUrls: vi.fn(),
+  registerAuthDeepLinkState: vi.fn((state?: string) => state ?? 'mock-state'),
+}));
 
 describe('WebCallbackPage', () => {
   afterEach(() => {
@@ -28,9 +31,10 @@ describe('WebCallbackPage', () => {
 
     expect(screen.getByText('Completing sign-in')).toBeInTheDocument();
     await waitFor(() => {
-      expect(handleDeepLinkUrls).toHaveBeenCalledWith([
-        'openhuman://auth?token=jwt-token&key=auth',
-      ]);
+      expect(handleDeepLinkUrls).toHaveBeenCalledWith(
+        ['openhuman://auth?token=jwt-token&key=auth'],
+        { requireStateNonce: false }
+      );
     });
   });
 
@@ -38,9 +42,10 @@ describe('WebCallbackPage', () => {
     renderRoute('/callback/oauth/success?provider=google&integrationId=int-1');
 
     await waitFor(() => {
-      expect(handleDeepLinkUrls).toHaveBeenCalledWith([
-        'openhuman://oauth/success?provider=google&integrationId=int-1',
-      ]);
+      expect(handleDeepLinkUrls).toHaveBeenCalledWith(
+        ['openhuman://oauth/success?provider=google&integrationId=int-1'],
+        { requireStateNonce: false }
+      );
     });
   });
 
diff --git a/app/src/services/coreRpcClient.ts b/app/src/services/coreRpcClient.ts
index bb10608de..2925f3e10 100644
--- a/app/src/services/coreRpcClient.ts
+++ b/app/src/services/coreRpcClient.ts
@@ -494,6 +494,14 @@ export async function getCoreHttpBaseUrl(): Promise<string> {
  *
  * The same helper is consumed by the WebhooksDebugPanel settings screen and
  * is the seam #1339 will reuse when the approvals SSE stream lands.
+ *
+ * SECURITY (audit U3): forwarding the long-lived bearer in the query string can
+ * leak into proxy/server logs. It is bounded today — `QUERY_TOKEN_PATHS`
+ * restricts query-token auth to `/events/webhooks`, the transport is
+ * HTTPS/loopback (plaintext HTTP is rejected off-localhost), and the FE never
+ * logs this URL. The proper fix is a short-lived single-use handshake token
+ * minted just before opening the stream; that requires a new core endpoint and
+ * is tracked as the follow-up to this seam. Do not log the returned URL.
  */
 export function buildWebhookEventsUrl(baseUrl: string, coreRpcToken: string | null): string | null {
   if (!coreRpcToken) return null;
diff --git a/app/src/utils/__tests__/desktopDeepLinkListener.test.ts b/app/src/utils/__tests__/desktopDeepLinkListener.test.ts
index eb41269c9..235b19f1b 100644
--- a/app/src/utils/__tests__/desktopDeepLinkListener.test.ts
+++ b/app/src/utils/__tests__/desktopDeepLinkListener.test.ts
@@ -9,7 +9,10 @@ import {
   subscribeDeepLinkAuthState,
 } from '../../store/deepLinkAuthState';
 import { getStoredCoreMode } from '../configPersistence';
-import { setupDesktopDeepLinkListener } from '../desktopDeepLinkListener';
+import {
+  registerAuthDeepLinkState,
+  setupDesktopDeepLinkListener,
+} from '../desktopDeepLinkListener';
 import { storeSession } from '../tauriCommands';
 
 vi.mock('../configPersistence', () => ({ getStoredCoreMode: vi.fn() }));
@@ -18,6 +21,14 @@ vi.mock('../../services/coreRpcClient', () => ({
   clearCoreRpcTokenCache: vi.fn(),
 }));
 
+// Build an `openhuman://auth` deep link bound to a freshly registered state
+// nonce, mirroring how the real OAuth button registers the loopback/deep-link
+// state before the callback returns (finding C3 CSRF guard).
+const authDeepLinkWithState = (query: string): string => {
+  const state = registerAuthDeepLinkState();
+  return `openhuman://auth?${query}&state=${state}`;
+};
+
 const waitForAuthSettled = (): Promise<void> =>
   new Promise(resolve => {
     if (!getDeepLinkAuthState().isProcessing) {
@@ -120,7 +131,7 @@ describe('desktopDeepLinkListener', () => {
       new Error('Decryption failed — wrong key or tampered data')
     );
 
-    vi.mocked(getCurrent).mockResolvedValue(['openhuman://auth?token=abc&key=auth']);
+    vi.mocked(getCurrent).mockResolvedValue([authDeepLinkWithState('token=abc&key=auth')]);
 
     await setupDesktopDeepLinkListener();
 
@@ -135,7 +146,7 @@ describe('desktopDeepLinkListener', () => {
   it('surfaces readiness failures instead of a generic sign-in error', async () => {
     waitForOAuthAuthReadiness.mockResolvedValueOnce({ ready: false, reason: 'core_mode_unset' });
 
-    vi.mocked(getCurrent).mockResolvedValue(['openhuman://auth?token=abc&key=auth']);
+    vi.mocked(getCurrent).mockResolvedValue([authDeepLinkWithState('token=abc&key=auth')]);
 
     await setupDesktopDeepLinkListener();
 
@@ -145,10 +156,68 @@ describe('desktopDeepLinkListener', () => {
     expect(storeSession).not.toHaveBeenCalled();
   });
 
+  it('rejects an auth deep link with no state nonce (CSRF guard, finding C3)', async () => {
+    // A hostile page can fire `openhuman://auth?token=<attacker_jwt>&key=auth`
+    // with no state — it must never apply a session token.
+    vi.mocked(getCurrent).mockResolvedValue(['openhuman://auth?token=attacker&key=auth']);
+
+    await setupDesktopDeepLinkListener();
+    await waitForAuthSettled();
+
+    expect(storeSession).not.toHaveBeenCalled();
+    const state = getDeepLinkAuthState();
+    expect(state.isProcessing).toBe(false);
+    expect(state.errorMessage).toBe('Sign-in could not be verified. Please start sign-in again.');
+  });
+
+  it('accepts a same-origin web callback without a state nonce when requireStateNonce=false', async () => {
+    // The web callback route (WebCallbackPage) is same-origin and not reachable
+    // via the OS `openhuman://` scheme, so it opts out of the C3 nonce guard.
+    await import('../desktopDeepLinkListener').then(m =>
+      m.handleDeepLinkUrls(['openhuman://auth?token=web-token&key=auth'], {
+        requireStateNonce: false,
+      })
+    );
+    await waitForAuthSettled();
+
+    expect(storeSession).toHaveBeenCalledWith('web-token', {});
+  });
+
+  it('rejects an auth deep link whose state nonce does not match a pending one', async () => {
+    registerAuthDeepLinkState('the-real-nonce');
+    vi.mocked(getCurrent).mockResolvedValue([
+      'openhuman://auth?token=attacker&key=auth&state=wrong-nonce',
+    ]);
+
+    await setupDesktopDeepLinkListener();
+    await waitForAuthSettled();
+
+    expect(storeSession).not.toHaveBeenCalled();
+    expect(getDeepLinkAuthState().errorMessage).toBe(
+      'Sign-in could not be verified. Please start sign-in again.'
+    );
+  });
+
+  it('consumes a state nonce one-shot so a replayed deep link is rejected', async () => {
+    const state = registerAuthDeepLinkState();
+    const url = `openhuman://auth?token=abc&key=auth&state=${state}`;
+
+    vi.mocked(getCurrent).mockResolvedValue([url]);
+    await setupDesktopDeepLinkListener();
+    await waitForAuthSettled();
+    expect(storeSession).toHaveBeenCalledWith('abc', {});
+
+    // Replay the exact same deep link — the nonce was consumed, so it fails.
+    vi.mocked(storeSession).mockClear();
+    await import('../desktopDeepLinkListener').then(m => m.handleDeepLinkUrls([url]));
+    await waitForAuthSettled();
+    expect(storeSession).not.toHaveBeenCalled();
+  });
+
   it('keeps requiresAppDataReset false for non-decryption auth failures', async () => {
     vi.mocked(storeSession).mockRejectedValueOnce(new Error('network down'));
 
-    vi.mocked(getCurrent).mockResolvedValue(['openhuman://auth?token=abc&key=auth']);
+    vi.mocked(getCurrent).mockResolvedValue([authDeepLinkWithState('token=abc&key=auth')]);
 
     await setupDesktopDeepLinkListener();
     await waitForAuthSettled();
@@ -173,7 +242,9 @@ describe('desktopDeepLinkListener', () => {
     ).__simulateDeepLink;
 
     expect(simulateDeepLink).toBeTypeOf('function');
-    await expect(simulateDeepLink!('openhuman://auth?token=abc&key=auth')).resolves.toBeUndefined();
+    await expect(
+      simulateDeepLink!('openhuman://auth?token=abc&key=auth&state=e2e-state-nonce')
+    ).resolves.toBeUndefined();
     expect(storeSession).not.toHaveBeenCalled();
 
     await new Promise(resolve => setTimeout(resolve, 0));
@@ -208,7 +279,7 @@ describe('desktopDeepLinkListener', () => {
 
   it('busts RPC caches before storeSession in cloud mode', async () => {
     vi.mocked(getStoredCoreMode).mockReturnValue('cloud');
-    vi.mocked(getCurrent).mockResolvedValue(['openhuman://auth?token=abc&key=auth']);
+    vi.mocked(getCurrent).mockResolvedValue([authDeepLinkWithState('token=abc&key=auth')]);
 
     await setupDesktopDeepLinkListener();
     await waitForAuthSettled();
@@ -220,7 +291,7 @@ describe('desktopDeepLinkListener', () => {
 
   it('does NOT bust RPC caches before storeSession in local mode', async () => {
     vi.mocked(getStoredCoreMode).mockReturnValue('local');
-    vi.mocked(getCurrent).mockResolvedValue(['openhuman://auth?token=abc&key=auth']);
+    vi.mocked(getCurrent).mockResolvedValue([authDeepLinkWithState('token=abc&key=auth')]);
 
     await setupDesktopDeepLinkListener();
     await waitForAuthSettled();
@@ -232,7 +303,7 @@ describe('desktopDeepLinkListener', () => {
 
   it('dispatches suppress-reauth before storeSession and clears it after in cloud mode', async () => {
     vi.mocked(getStoredCoreMode).mockReturnValue('cloud');
-    vi.mocked(getCurrent).mockResolvedValue(['openhuman://auth?token=abc&key=auth']);
+    vi.mocked(getCurrent).mockResolvedValue([authDeepLinkWithState('token=abc&key=auth')]);
 
     const suppressEvents: Array<{ until: number }> = [];
     window.addEventListener('core-state:suppress-reauth', event => {
diff --git a/app/src/utils/configPersistence.ts b/app/src/utils/configPersistence.ts
index f3737b530..0de448105 100644
--- a/app/src/utils/configPersistence.ts
+++ b/app/src/utils/configPersistence.ts
@@ -20,6 +20,15 @@ const RPC_URL_STORAGE_KEY = 'openhuman_core_rpc_url';
 // Storage key for cloud-mode bearer token. Pre-login and per-device, parallel
 // to the URL key. Held in plain localStorage because the cloud picker runs
 // before any user session exists.
+//
+// SECURITY (audit U3): a renderer XSS could read this long-lived bearer
+// directly. We keep localStorage for now — there is no generic OS-keychain
+// set/get exposed to the renderer (`keyringApi` is consent-only; the keychain
+// plugin is a `profileStore.ts` TODO) and the cloud picker must persist the
+// token before any session/keychain consent exists. When a generic keychain
+// command lands, migrate this key to it and scope the bearer's lifetime.
+// Defense-in-depth for the read path is handled by tightening the renderer CSP
+// (audit U1) so injected markup cannot exfiltrate it.
 const CORE_TOKEN_STORAGE_KEY = 'openhuman_core_rpc_token';
 
 // Storage key for the user-chosen core mode ('local' | 'cloud'). Mirrors the
diff --git a/app/src/utils/desktopDeepLinkListener.ts b/app/src/utils/desktopDeepLinkListener.ts
index e1517c352..74a936669 100644
--- a/app/src/utils/desktopDeepLinkListener.ts
+++ b/app/src/utils/desktopDeepLinkListener.ts
@@ -23,6 +23,80 @@ import { isTauri as coreIsTauri } from './tauriCommands/common';
 
 const SESSION_TOKEN_UPDATED_EVENT = 'core-state:session-token-updated';
 
+/**
+ * CSRF / session-fixation protection for `openhuman://auth` deep links (finding
+ * C3). Because `openhuman://` is an OS-registered scheme, ANY web page the
+ * victim visits can navigate to `openhuman://auth?token=<attacker_jwt>&key=auth`
+ * and silently log them into the attacker's account. We defend by binding every
+ * auth deep link to a per-attempt `state` nonce that is generated *in-app*
+ * before the login/OAuth flow starts, held only in memory, and required +
+ * constant-time-compared in `handleAuthDeepLink`. A deep link with no `state`,
+ * or a `state` that does not match a pending nonce, is rejected before any token
+ * is applied.
+ */
+const pendingAuthDeepLinkStates = new Set<string>();
+
+/**
+ * Register an auth deep-link `state` nonce as pending and return it so the
+ * caller can carry it through the OAuth/login round-trip (the backend echoes it
+ * back on the callback URL). Callers MUST invoke this before starting the flow
+ * so the resulting `openhuman://auth?...&state=<nonce>` deep link can be
+ * verified on return.
+ *
+ * Pass an existing `state` (e.g. the loopback handle's Rust-verified nonce) to
+ * register that value; omit it to mint a fresh one for the bare deep-link path.
+ */
+export const registerAuthDeepLinkState = (state?: string): string => {
+  const nonce = state && state.length > 0 ? state : generateAuthDeepLinkState();
+  pendingAuthDeepLinkStates.add(nonce);
+  return nonce;
+};
+
+const generateAuthDeepLinkState = (): string => {
+  const bytes = new Uint8Array(32);
+  crypto.getRandomValues(bytes);
+  return Array.from(bytes, b => b.toString(16).padStart(2, '0')).join('');
+};
+
+/**
+ * Constant-time string comparison so a mismatch can't be probed byte-by-byte
+ * via timing. Returns false for length mismatches without short-circuiting on
+ * the contents.
+ */
+const constantTimeEquals = (a: string, b: string): boolean => {
+  if (a.length !== b.length) {
+    return false;
+  }
+  let diff = 0;
+  for (let i = 0; i < a.length; i += 1) {
+    diff |= a.charCodeAt(i) ^ b.charCodeAt(i);
+  }
+  return diff === 0;
+};
+
+/**
+ * Verify an inbound auth deep-link `state` against the set of pending nonces
+ * using a constant-time compare, and consume (one-shot) the matched nonce.
+ * Returns false if `state` is absent or matches nothing.
+ */
+const verifyAndConsumeAuthDeepLinkState = (state: string | null): boolean => {
+  if (!state) {
+    return false;
+  }
+  let matched: string | null = null;
+  for (const candidate of pendingAuthDeepLinkStates) {
+    if (constantTimeEquals(candidate, state)) {
+      matched = candidate;
+      // Do not break — keep the comparison count independent of position.
+    }
+  }
+  if (matched === null) {
+    return false;
+  }
+  pendingAuthDeepLinkStates.delete(matched);
+  return true;
+};
+
 const sanitizeOAuthDiagnosticValue = (
   value: string | null,
   fallback: string,
@@ -102,16 +176,35 @@ const applySessionToken = async (sessionToken: string): Promise<void> => {
 
 /**
  * Handle an `openhuman://auth?token=...` deep link for login.
+ *
+ * `requireStateNonce` defaults to true for genuine OS-registered custom-scheme
+ * deep links (the finding C3 vector — any external app can trigger
+ * `openhuman://`). The same-origin web callback route (`WebCallbackPage`) passes
+ * `false`: it is reached only through the app's own routing / the backend OAuth
+ * redirect on the same origin, not via the OS scheme, so it is outside C3's scope.
  */
-const handleAuthDeepLink = async (parsed: URL) => {
+const handleAuthDeepLink = async (parsed: URL, requireStateNonce = true) => {
   const token = parsed.searchParams.get('token');
   const key = parsed.searchParams.get('key');
+  const state = parsed.searchParams.get('state');
   if (!token) {
     console.warn('[DeepLink] URL did not contain a token query parameter');
     failDeepLinkAuthProcessing('Sign-in callback was missing a token. Please try again.');
     return;
   }
 
+  // CSRF / session-fixation guard (finding C3): only honour an auth deep link
+  // whose `state` matches a nonce this app generated before starting the flow.
+  // This is what stops a hostile page from triggering the OS custom scheme
+  // `openhuman://auth?token=<attacker_jwt>&key=auth` and silently logging the
+  // victim into the attacker's account. The `key=auth` raw-JWT path in
+  // particular is ONLY safe behind this check on the custom-scheme transport.
+  if (requireStateNonce && !verifyAndConsumeAuthDeepLinkState(state)) {
+    console.warn('[DeepLink][auth] rejecting auth deep link: missing or unrecognized state nonce');
+    failDeepLinkAuthProcessing('Sign-in could not be verified. Please start sign-in again.');
+    return;
+  }
+
   beginDeepLinkAuthProcessing();
 
   try {
@@ -319,7 +412,10 @@ const handleOAuthDeepLink = async (parsed: URL) => {
  *   - `openhuman://payment/success?session_id=...` → Stripe payment confirmation
  *   - `openhuman://payment/cancel` → Stripe payment cancellation
  */
-export const handleDeepLinkUrls = async (urls: string[] | null | undefined) => {
+export const handleDeepLinkUrls = async (
+  urls: string[] | null | undefined,
+  options?: { requireStateNonce?: boolean }
+) => {
   if (!urls || urls.length === 0) {
     return;
   }
@@ -335,7 +431,7 @@ export const handleDeepLinkUrls = async (urls: string[] | null | undefined) => {
 
     switch (parsed.hostname) {
       case 'auth':
-        await handleAuthDeepLink(parsed);
+        await handleAuthDeepLink(parsed, options?.requireStateNonce ?? true);
         break;
       case 'oauth':
         await handleOAuthDeepLink(parsed);
@@ -380,7 +476,28 @@ export const setupDesktopDeepLinkListener = async () => {
       // window.__simulateDeepLink('openhuman://oauth/success?integrationId=69cafd0b103bd070232d3223&skillId=discord')
       const win = window as Window & { __simulateDeepLink?: (url: string) => Promise<void> };
       win.__simulateDeepLink = async (url: string) => {
-        void handleDeepLinkUrls([url]);
+        // Dev/E2E convenience: simulated `openhuman://auth` links don't come from
+        // the real OAuth button, so they have no registered `state` nonce. Mint
+        // and attach one here so the CSRF guard (finding C3) accepts them without
+        // every spec having to script the button flow. This is safe because the
+        // helper is a test-only affordance — real inbound deep links go straight
+        // through `onOpenUrl`/`getCurrent` and never touch this code path.
+        let effectiveUrl = url;
+        try {
+          const parsed = new URL(url);
+          if (parsed.protocol === 'openhuman:' && parsed.hostname === 'auth') {
+            const existing = parsed.searchParams.get('state');
+            if (existing) {
+              registerAuthDeepLinkState(existing);
+            } else {
+              parsed.searchParams.set('state', registerAuthDeepLinkState());
+              effectiveUrl = parsed.toString();
+            }
+          }
+        } catch {
+          // Fall through — handleDeepLinkUrls will report the parse failure.
+        }
+        void handleDeepLinkUrls([effectiveUrl]);
       };
     }
   } catch (err) {
diff --git a/app/test/OAuthDiscord.test.tsx b/app/test/OAuthDiscord.test.tsx
index c81942c43..ec16cf0e5 100644
--- a/app/test/OAuthDiscord.test.tsx
+++ b/app/test/OAuthDiscord.test.tsx
@@ -140,7 +140,7 @@ describe('OAuthProviderButton (Discord) — web OAuth flow', () => {
     await clickButton(screen.getByRole('button', { name: /discord/i }));
 
     await waitFor(() => {
-      expect((window.location as unknown as { href: string }).href).toBe(
+      expect((window.location as unknown as { href: string }).href).toContain(
         'http://localhost:5005/auth/discord/login?responseType=json'
       );
     });
@@ -180,7 +180,7 @@ describe('OAuthProviderButton (Discord) — Tauri OAuth flow', () => {
 
     await waitFor(() => {
       expect(mockOpenUrl).toHaveBeenCalledWith(
-        'https://api.example.com/auth/discord/login?responseType=json'
+        expect.stringContaining('https://api.example.com/auth/discord/login?responseType=json')
       );
     });
   });
@@ -335,7 +335,7 @@ describe('OAuthProviderButton (Discord) — URL construction', () => {
     await clickButton(screen.getByRole('button', { name: /discord/i }));
 
     await waitFor(() => expect(mockOpenUrl).toHaveBeenCalled());
-    expect(mockOpenUrl.mock.calls[0][0]).toBe(
+    expect(mockOpenUrl.mock.calls[0][0]).toContain(
       'https://api.example.com/auth/discord/login?responseType=json'
     );
   });
diff --git a/app/test/OAuthGitHub.test.tsx b/app/test/OAuthGitHub.test.tsx
index 17ca6550c..2b7aec5f9 100644
--- a/app/test/OAuthGitHub.test.tsx
+++ b/app/test/OAuthGitHub.test.tsx
@@ -140,7 +140,7 @@ describe('OAuthProviderButton (GitHub) — web OAuth flow', () => {
     await clickButton(screen.getByRole('button', { name: /github/i }));
 
     await waitFor(() => {
-      expect((window.location as unknown as { href: string }).href).toBe(
+      expect((window.location as unknown as { href: string }).href).toContain(
         'http://localhost:5005/auth/github/login?responseType=json'
       );
     });
@@ -180,7 +180,7 @@ describe('OAuthProviderButton (GitHub) — Tauri OAuth flow', () => {
 
     await waitFor(() => {
       expect(mockOpenUrl).toHaveBeenCalledWith(
-        'https://api.example.com/auth/github/login?responseType=json'
+        expect.stringContaining('https://api.example.com/auth/github/login?responseType=json')
       );
     });
   });
@@ -335,7 +335,7 @@ describe('OAuthProviderButton (GitHub) — URL construction', () => {
     await clickButton(screen.getByRole('button', { name: /github/i }));
 
     await waitFor(() => expect(mockOpenUrl).toHaveBeenCalled());
-    expect(mockOpenUrl.mock.calls[0][0]).toBe(
+    expect(mockOpenUrl.mock.calls[0][0]).toContain(
       'https://api.example.com/auth/github/login?responseType=json'
     );
   });
diff --git a/app/test/OAuthLoginSection.test.tsx b/app/test/OAuthLoginSection.test.tsx
index c4e688f6b..ea75250de 100644
--- a/app/test/OAuthLoginSection.test.tsx
+++ b/app/test/OAuthLoginSection.test.tsx
@@ -191,7 +191,7 @@ describe('OAuthProviderButton (Google) — web OAuth flow', () => {
     await clickButton(screen.getByRole('button', { name: /google/i }));
 
     await waitFor(() => {
-      expect((window.location as unknown as { href: string }).href).toBe(
+      expect((window.location as unknown as { href: string }).href).toContain(
         'http://localhost:5005/auth/google/login?responseType=json'
       );
     });
@@ -231,7 +231,7 @@ describe('OAuthProviderButton (Google) — Tauri OAuth flow', () => {
 
     await waitFor(() => {
       expect(mockOpenUrl).toHaveBeenCalledWith(
-        'https://api.example.com/auth/google/login?responseType=json'
+        expect.stringContaining('https://api.example.com/auth/google/login?responseType=json')
       );
     });
   });
@@ -388,7 +388,7 @@ describe('OAuthProviderButton (Google) — dev mode URL params', () => {
     await waitFor(() => expect(mockOpenUrl).toHaveBeenCalled());
     const calledUrl: string = mockOpenUrl.mock.calls[0][0];
     expect(calledUrl).toContain('?responseType=json');
-    expect(calledUrl).toBe('https://api.example.com/auth/google/login?responseType=json');
+    expect(calledUrl).toContain('https://api.example.com/auth/google/login?responseType=json');
   });
 
   it('appends ?responseType=json to the Google OAuth URL in dev mode (web)', async () => {
@@ -403,7 +403,7 @@ describe('OAuthProviderButton (Google) — dev mode URL params', () => {
     await clickButton(screen.getByRole('button', { name: /google/i }));
 
     await waitFor(() => expect((window.location as unknown as { href: string }).href).not.toBe(''));
-    expect((window.location as unknown as { href: string }).href).toBe(
+    expect((window.location as unknown as { href: string }).href).toContain(
       'https://api.example.com/auth/google/login?responseType=json'
     );
 
diff --git a/app/test/OAuthTwitter.test.tsx b/app/test/OAuthTwitter.test.tsx
index a6331ba64..0ffc92890 100644
--- a/app/test/OAuthTwitter.test.tsx
+++ b/app/test/OAuthTwitter.test.tsx
@@ -140,7 +140,7 @@ describe('OAuthProviderButton (Twitter) — web OAuth flow', () => {
     await clickButton(screen.getByRole('button', { name: /twitter/i }));
 
     await waitFor(() => {
-      expect((window.location as unknown as { href: string }).href).toBe(
+      expect((window.location as unknown as { href: string }).href).toContain(
         'http://localhost:5005/auth/twitter/login?responseType=json'
       );
     });
@@ -180,7 +180,7 @@ describe('OAuthProviderButton (Twitter) — Tauri OAuth flow', () => {
 
     await waitFor(() => {
       expect(mockOpenUrl).toHaveBeenCalledWith(
-        'https://api.example.com/auth/twitter/login?responseType=json'
+        expect.stringContaining('https://api.example.com/auth/twitter/login?responseType=json')
       );
     });
   });
@@ -335,7 +335,7 @@ describe('OAuthProviderButton (Twitter) — URL construction', () => {
     await clickButton(screen.getByRole('button', { name: /twitter/i }));
 
     await waitFor(() => expect(mockOpenUrl).toHaveBeenCalled());
-    expect(mockOpenUrl.mock.calls[0][0]).toBe(
+    expect(mockOpenUrl.mock.calls[0][0]).toContain(
       'https://api.example.com/auth/twitter/login?responseType=json'
     );
   });
diff --git a/src/core/all.rs b/src/core/all.rs
index d4d2b5e0a..1b7ad021e 100644
--- a/src/core/all.rs
+++ b/src/core/all.rs
@@ -648,9 +648,113 @@ pub fn validate_params(
         }
     }
 
+    // Type-check each present param against its declared `TypeSchema`, so every
+    // controller gets uniform validation before dispatch rather than relying on
+    // each handler's `serde_json::from_value`. Absent (optional) params are
+    // already handled by the required-presence check above.
+    for input in &schema.inputs {
+        if let Some(value) = params.get(input.name) {
+            check_type(value, &input.ty).map_err(|expected| {
+                format!(
+                    "invalid type for param '{}' in {}.{}: expected {}, got {}",
+                    input.name,
+                    schema.namespace,
+                    schema.function,
+                    expected,
+                    json_type_name(value),
+                )
+            })?;
+        }
+    }
+
     Ok(())
 }
 
+/// A short, human-readable name for the JSON kind of `value`, used in
+/// `validate_params` type-mismatch errors.
+fn json_type_name(value: &Value) -> &'static str {
+    match value {
+        Value::Null => "null",
+        Value::Bool(_) => "bool",
+        Value::Number(_) => "number",
+        Value::String(_) => "string",
+        Value::Array(_) => "array",
+        Value::Object(_) => "object",
+    }
+}
+
+/// Validate a JSON `value` against a declared [`TypeSchema`].
+///
+/// Returns `Ok(())` on a match, or `Err(expected)` where `expected` is a short
+/// description of the type that was required. Unknown/opaque shapes
+/// (`Json`, `Bytes`, `Ref`) accept any value — they are validated by the
+/// handler's typed deserialization.
+fn check_type(value: &Value, ty: &crate::core::TypeSchema) -> Result<(), &'static str> {
+    use crate::core::TypeSchema;
+
+    // JSON-RPC semantics (preserved from the prior presence-only check):
+    // an explicit `null` satisfies validation for any declared type. Required
+    // fields are checked for *presence*, not value; stronger contracts are
+    // enforced by the handler's typed deserialization.
+    if value.is_null() {
+        return Ok(());
+    }
+
+    match ty {
+        // Opaque / handler-validated shapes accept any JSON value.
+        //
+        // Structured types (`Object`/`Map`/`Ref`) are deliberately lenient: a
+        // struct field may have a custom `Deserialize` impl that accepts more
+        // than one JSON shape (e.g. `agent_registry.update`'s `subagents`
+        // accepts both `{ "allowlist": [...] }` and a legacy bare array), and
+        // the declared schema can only describe one of them. Strictly checking
+        // the JSON kind here would reject inputs the handler's `serde_json`
+        // deserialization accepts. We therefore keep pre-dispatch validation to
+        // scalar leaf types (where a type confusion would otherwise reach an
+        // `as_str()/as_u64()`-style accessor) and defer object/map shape
+        // validation to the handler.
+        TypeSchema::Json
+        | TypeSchema::Bytes
+        | TypeSchema::Ref(_)
+        | TypeSchema::Object { .. }
+        | TypeSchema::Map(_) => Ok(()),
+
+        TypeSchema::Bool => value.is_boolean().then_some(()).ok_or("bool"),
+        TypeSchema::String => value.is_string().then_some(()).ok_or("string"),
+        TypeSchema::I64 => value.is_i64().then_some(()).ok_or("integer"),
+        TypeSchema::U64 => value.is_u64().then_some(()).ok_or("unsigned integer"),
+        TypeSchema::F64 => {
+            // Accept any JSON number (ints are valid floats).
+            value.is_number().then_some(()).ok_or("number")
+        }
+
+        // `Option<T>` accepts null or a value matching the inner type.
+        TypeSchema::Option(inner) => {
+            if value.is_null() {
+                Ok(())
+            } else {
+                check_type(value, inner)
+            }
+        }
+
+        TypeSchema::Array(inner) => match value.as_array() {
+            Some(items) => {
+                for item in items {
+                    check_type(item, inner)?;
+                }
+                Ok(())
+            }
+            None => Err("array"),
+        },
+
+        TypeSchema::Enum { variants } => match value.as_str() {
+            Some(s) if variants.contains(&s) => Ok(()),
+            Some(_) => Err("one of the allowed enum variants"),
+            None => Err("string"),
+        },
+    }
+}
+
 /// Attempts to invoke a registered RPC method by name.
 ///
 /// Checks both the agent-facing controller registry and the internal-only registry,
diff --git a/src/core/all_tests.rs b/src/core/all_tests.rs
index 3da14fb62..d0f8fadff 100644
--- a/src/core/all_tests.rs
+++ b/src/core/all_tests.rs
@@ -361,6 +361,138 @@ fn validate_params_null_for_required_is_acceptable() {
     assert!(validate_params(&s, &p).is_ok());
 }
 
+// --- validate_params type checking (C12) --------------------------------
+
+#[test]
+fn validate_params_rejects_wrong_scalar_type() {
+    let s = schema(
+        "test",
+        "fn",
+        vec![FieldSchema {
+            name: "count",
+            ty: TypeSchema::U64,
+            comment: "",
+            required: true,
+        }],
+    );
+    let mut p = Map::new();
+    p.insert("count".into(), Value::String("nope".into()));
+    let err = validate_params(&s, &p).unwrap_err();
+    assert!(err.contains("invalid type for param 'count'"), "got: {err}");
+    assert!(err.contains("expected unsigned integer"), "got: {err}");
+}
+
+#[test]
+fn validate_params_accepts_correct_scalar_type() {
+    let s = schema(
+        "test",
+        "fn",
+        vec![FieldSchema {
+            name: "flag",
+            ty: TypeSchema::Bool,
+            comment: "",
+            required: true,
+        }],
+    );
+    let mut p = Map::new();
+    p.insert("flag".into(), Value::Bool(true));
+    assert!(validate_params(&s, &p).is_ok());
+}
+
+#[test]
+fn validate_params_validates_array_element_types() {
+    let s = schema(
+        "test",
+        "fn",
+        vec![FieldSchema {
+            name: "ids",
+            ty: TypeSchema::Array(Box::new(TypeSchema::String)),
+            comment: "",
+            required: true,
+        }],
+    );
+    let mut ok = Map::new();
+    ok.insert(
+        "ids".into(),
+        Value::Array(vec![Value::String("a".into()), Value::String("b".into())]),
+    );
+    assert!(validate_params(&s, &ok).is_ok());
+
+    let mut bad = Map::new();
+    bad.insert(
+        "ids".into(),
+        Value::Array(vec![Value::String("a".into()), Value::Bool(true)]),
+    );
+    let err = validate_params(&s, &bad).unwrap_err();
+    assert!(err.contains("invalid type for param 'ids'"), "got: {err}");
+}
+
+#[test]
+fn validate_params_enforces_enum_variants() {
+    let s = schema(
+        "test",
+        "fn",
+        vec![FieldSchema {
+            name: "mode",
+            ty: TypeSchema::Enum {
+                variants: vec!["read", "write"],
+            },
+            comment: "",
+            required: true,
+        }],
+    );
+    let mut ok = Map::new();
+    ok.insert("mode".into(), Value::String("read".into()));
+    assert!(validate_params(&s, &ok).is_ok());
+
+    let mut bad = Map::new();
+    bad.insert("mode".into(), Value::String("delete".into()));
+    let err = validate_params(&s, &bad).unwrap_err();
+    assert!(err.contains("enum variants"), "got: {err}");
+}
+
+#[test]
+fn validate_params_option_accepts_null_and_inner_type() {
+    let s = schema(
+        "test",
+        "fn",
+        vec![FieldSchema {
+            name: "limit",
+            ty: TypeSchema::Option(Box::new(TypeSchema::U64)),
+            comment: "",
+            required: false,
+        }],
+    );
+    let mut null_p = Map::new();
+    null_p.insert("limit".into(), Value::Null);
+    assert!(validate_params(&s, &null_p).is_ok());
+
+    let mut val_p = Map::new();
+    val_p.insert("limit".into(), Value::Number(5.into()));
+    assert!(validate_params(&s, &val_p).is_ok());
+
+    let mut bad_p = Map::new();
+    bad_p.insert("limit".into(), Value::String("x".into()));
+    assert!(validate_params(&s, &bad_p).is_err());
+}
+
+#[test]
+fn validate_params_json_type_accepts_anything() {
+    let s = schema(
+        "test",
+        "fn",
+        vec![FieldSchema {
+            name: "payload",
+            ty: TypeSchema::Json,
+            comment: "",
+            required: true,
+        }],
+    );
+    let mut p = Map::new();
+    p.insert("payload".into(), Value::Array(vec![Value::Bool(true)]));
+    assert!(validate_params(&s, &p).is_ok());
+}
+
 // --- validate_registry edge cases ---------------------------------------
 
 #[test]
diff --git a/src/core/auth.rs b/src/core/auth.rs
index 5d03b5a77..523e99e75 100644
--- a/src/core/auth.rs
+++ b/src/core/auth.rs
@@ -34,8 +34,13 @@
 //!                          one-time login tokens, never raw session JWTs
 //! - `GET /auth/telegram` — external browser callback (carries its own token)
 //! - `GET /schema`        — read-only schema discovery
-//! - `GET /events`        — SSE stream; browser `EventSource` cannot set headers
-//! - `GET /ws/dictation`  — WebSocket upgrade; browser WS API cannot set headers
+//! - `GET /events`        — SSE stream; browser `EventSource` cannot set
+//!                          headers, so the handler enforces a bind-token /
+//!                          bearer credential itself
+//! - `GET /ws/dictation`  — WebSocket upgrade; browser WS API cannot set
+//!                          headers, so the handler enforces the bearer
+//!                          (header or `?token=`) + origin itself before the
+//!                          upgrade (C4 / issue #1924)
 //! - `OPTIONS *`          — CORS preflight (handled by outer CORS middleware)
 //!
 //! Endpoints that accept the bearer either via header **or** `?token=…` query
@@ -71,10 +76,15 @@ static RPC_TOKEN: OnceLock<String> = OnceLock::new();
 
 /// Paths that bypass bearer-token authentication.
 ///
-/// `/rpc` and `/v1/*` carry executable surfaces and must be protected. All
-/// other routes are read-only, streaming, or WebSocket upgrades whose clients
-/// (browser `EventSource`, browser `WebSocket`) cannot set `Authorization`
-/// headers via standard APIs.
+/// `/rpc` and `/v1/*` carry executable surfaces and must be protected. The
+/// other routes are read-only, or are streaming / WebSocket upgrades whose
+/// clients (browser `EventSource`, browser `WebSocket`) cannot set
+/// `Authorization` headers via standard APIs. `/events` is not unauthenticated
+/// — it is exempt from the *middleware* header check but enforces its own
+/// bind-token credential inside the handler. `/ws/dictation` is NOT public: it
+/// is bearer-gated by this middleware via [`QUERY_TOKEN_PATHS`] (header or
+/// `?token=`) so an unauthenticated upgrade is rejected with 401 before the
+/// WebSocket handshake; the handler adds an origin check on top (finding C4).
 const PUBLIC_PATHS: &[&str] = &[
     "/",
     "/health",
@@ -86,7 +96,6 @@ const PUBLIC_PATHS: &[&str] = &[
     "/oauth/mcp/callback",
     "/schema",
     "/events",
-    "/ws/dictation",
 ];
 
 /// Paths that may authenticate via `?token=…` in the URL when no
@@ -102,7 +111,7 @@ const PUBLIC_PATHS: &[&str] = &[
 /// Add new entries here only for SSE / WebSocket routes whose clients cannot
 /// send headers and that carry per-user data. The follow-up approvals stream
 /// (#1339) is the next planned addition.
-const QUERY_TOKEN_PATHS: &[&str] = &["/events/webhooks"];
+const QUERY_TOKEN_PATHS: &[&str] = &["/events/webhooks", "/ws/dictation"];
 
 /// Operator-supplied environment variable that carries the RPC bearer in
 /// non-desktop deployments.
diff --git a/src/core/jsonrpc.rs b/src/core/jsonrpc.rs
index 5045dd8f3..7fdfb00bd 100644
--- a/src/core/jsonrpc.rs
+++ b/src/core/jsonrpc.rs
@@ -917,9 +917,84 @@ async fn desktop_auth_handler(
     )
 }
 
+/// Query parameters for the dictation WebSocket endpoint.
+///
+/// Browser `WebSocket` cannot attach an `Authorization` header on upgrade, so
+/// the FE forwards the per-process core bearer as a `?token=…` query param —
+/// validated against the same in-process RPC token via [`verify_bearer_token`]
+/// (single source of truth, no separate credential).
+#[derive(Debug, serde::Deserialize)]
+struct DictationQuery {
+    #[serde(default)]
+    token: Option<String>,
+}
+
 /// WebSocket upgrade handler for streaming voice dictation.
-async fn dictation_ws_handler(ws: WebSocketUpgrade) -> Response {
+///
+/// Authenticated before upgrade (C4 / issue #1924): the request must carry the
+/// per-process core bearer either as `Authorization: Bearer <token>` (CLI /
+/// native callers) or as `?token=<token>` (browser `WebSocket`, which cannot
+/// set headers), and — when an `Origin` header is present — that origin must be
+/// on the local-app allowlist, mirroring the Socket.IO handshake check. Missing
+/// or wrong credentials are rejected with 401 and the socket is never upgraded.
+async fn dictation_ws_handler(
+    headers: axum::http::HeaderMap,
+    Query(query): Query<DictationQuery>,
+    ws: WebSocketUpgrade,
+) -> Response {
     log::info!("[ws] dictation WebSocket upgrade requested");
+
+    // Origin check (same allowlist Socket.IO enforces): native clients send no
+    // Origin and are accepted; cross-origin browser pages are rejected even if
+    // they somehow hold the bearer.
+    let origin = headers
+        .get(header::ORIGIN)
+        .and_then(|v| v.to_str().ok())
+        .map(str::trim);
+    if !crate::core::socketio::origin_is_allowed(origin) {
+        log::warn!("[ws] dictation upgrade rejected: disallowed origin {origin:?}");
+        return (
+            StatusCode::FORBIDDEN,
+            Json(json!({
+                "ok": false,
+                "error": "forbidden",
+                "message": "Origin not allowed for the dictation WebSocket."
+            })),
+        )
+            .into_response();
+    }
+
+    // Bearer check: header first, then `?token=` for browser WebSocket clients.
+    let header_token = headers
+        .get(header::AUTHORIZATION)
+        .and_then(|v| v.to_str().ok())
+        .and_then(|v| v.strip_prefix("Bearer "))
+        .map(str::trim)
+        .filter(|s| !s.is_empty());
+    let bearer_ok = header_token
+        .map(crate::core::auth::verify_bearer_token)
+        .unwrap_or(false);
+    let bearer_ok = bearer_ok
+        || query
+            .token
+            .as_deref()
+            .map(str::trim)
+            .filter(|s| !s.is_empty())
+            .map(crate::core::auth::verify_bearer_token)
+            .unwrap_or(false);
+    if !bearer_ok {
+        log::warn!("[ws] dictation upgrade rejected: missing or invalid bearer token");
+        return (
+            StatusCode::UNAUTHORIZED,
+            Json(json!({
+                "ok": false,
+                "error": "unauthorized",
+                "message": "Missing or invalid token. Supply 'Authorization: Bearer <core>' or ?token=<core>."
+            })),
+        )
+            .into_response();
+    }
+
     ws.on_upgrade(|socket| async move {
         let config = match crate::openhuman::config::rpc::load_config_with_timeout().await {
             Ok(c) => Arc::new(c),
@@ -1713,25 +1788,37 @@ async fn run_server_inner(
             .ok()
             .filter(|s| !s.trim().is_empty())
             .is_some();
-        // Auth subsystem was already initialised above; fall back to the live
-        // token if neither input matched but somehow a token is seeded (e.g.
-        // a future caller route that doesn't thread the value through here).
-        let has_initialized_token = crate::core::auth::get_rpc_token()
-            .map(|t| !t.trim().is_empty())
-            .unwrap_or(false);
-        let has_explicit_token = has_in_memory_token || has_env_token || has_initialized_token;
+        // Fail closed (#1919): a non-loopback bind exposes the entire RPC
+        // surface (tool execution, file access, credentials) to the network,
+        // so it must be guarded by an OPERATOR-supplied bearer. Only an
+        // explicit operator token counts here:
+        //   - in-memory handoff from the embedded caller (`rpc_token`), or
+        //   - `OPENHUMAN_CORE_TOKEN` in the process environment.
+        // The self-generated `core.token` file (which `init_rpc_token` may
+        // already have seeded into the auth subsystem above) does NOT satisfy
+        // this requirement: remote clients cannot read that file, so treating
+        // it as "explicit" would be fail-open. Refuse to bind instead of
+        // serving an effectively unauthenticated network surface.
+        let has_explicit_token = has_in_memory_token || has_env_token;
         if !has_explicit_token {
             log::error!(
-                "[core] ⚠️  SECURITY WARNING: Binding on public address {resolved_host} without \
-                 an explicit OPENHUMAN_CORE_TOKEN. The RPC server will auto-generate a token, \
-                 but external clients will not know it. Set OPENHUMAN_CORE_TOKEN in your \
-                 .env file to secure the RPC endpoint."
+                "[core] SECURITY: refusing to bind on public address {resolved_host} without an \
+                 explicit operator-supplied RPC token. Set {} in your environment (or hand the \
+                 bearer in-memory via the embedded core handle) to secure the RPC endpoint.",
+                crate::core::auth::CORE_TOKEN_ENV_VAR
             );
             eprintln!(
-                "\n\x1b[1;31m[SECURITY]\x1b[0m Binding on {resolved_host} without OPENHUMAN_CORE_TOKEN.\n\
-                 Set OPENHUMAN_CORE_TOKEN in .env to secure the RPC endpoint.\n\
-                 Without it, the auto-generated token is written to {{workspace}}/core.token\n\
-                 but remote clients will not be able to authenticate.\n"
+                "\n\x1b[1;31m[SECURITY]\x1b[0m Refusing to bind on {resolved_host} without {}.\n\
+                 The auto-generated {{workspace}}/core.token does NOT secure a public bind —\n\
+                 remote clients cannot read it. Set {} in your environment to secure the\n\
+                 RPC endpoint, or bind on a loopback address.\n",
+                crate::core::auth::CORE_TOKEN_ENV_VAR,
+                crate::core::auth::CORE_TOKEN_ENV_VAR
+            );
+            anyhow::bail!(
+                "refusing to bind on non-loopback address {resolved_host} without an explicit \
+                 operator-supplied RPC token ({})",
+                crate::core::auth::CORE_TOKEN_ENV_VAR
             );
         }
     }
diff --git a/src/core/socketio.rs b/src/core/socketio.rs
index 317efb3cb..d3f243019 100644
--- a/src/core/socketio.rs
+++ b/src/core/socketio.rs
@@ -47,7 +47,7 @@ struct HandshakeAuth {
 /// A missing `Origin` header is treated as a native (non-browser) client
 /// and accepted — only the cross-origin browser-page case is the targeted
 /// bad actor here.
-fn origin_is_allowed(origin: Option<&str>) -> bool {
+pub(crate) fn origin_is_allowed(origin: Option<&str>) -> bool {
     let Some(origin) = origin else {
         return true; // native clients (CLI, Tauri shell) — no Origin header
     };
diff --git a/src/openhuman/config/schema/load/impl_load.rs b/src/openhuman/config/schema/load/impl_load.rs
index 60b067c46..0dc80c535 100644
--- a/src/openhuman/config/schema/load/impl_load.rs
+++ b/src/openhuman/config/schema/load/impl_load.rs
@@ -238,7 +238,20 @@ impl Config {
                 "Config loaded"
             );
             crate::openhuman::migrations::run_pending(&mut config).await;
-            decrypt_config_secrets(&mut config, &openhuman_dir)?;
+            let migrated_legacy_secrets = decrypt_config_secrets(&mut config, &openhuman_dir)?;
+            if migrated_legacy_secrets {
+                // One-time forced migration: a legacy `enc:` (XOR) secret was
+                // upgraded to `enc2:` on read. Persist immediately so the
+                // insecure ciphertext stops living on disk (audit C8). A save
+                // failure is non-fatal — the config is still usable in memory
+                // and migration will be retried on the next startup.
+                if let Err(e) = config.save().await {
+                    log::warn!(
+                        "[security][config] failed to persist enc: -> enc2: secret migration; \
+                         will retry on next startup: {e}"
+                    );
+                }
+            }
             Ok(config)
         } else {
             let mut config = Config {
@@ -304,7 +317,9 @@ impl Config {
         config.workspace_dir = workspace_dir;
         config.action_dir = resolve_action_dir(&config.action_dir_override);
         config.apply_env_overrides();
-        decrypt_config_secrets(&mut config, &openhuman_dir)?;
+        // Debug-dump path is read-only; ignore the migration signal (the
+        // authoritative `load_or_init` path persists upgraded secrets).
+        let _ = decrypt_config_secrets(&mut config, &openhuman_dir)?;
         Ok(config)
     }
 
diff --git a/src/openhuman/config/schema/load/secrets.rs b/src/openhuman/config/schema/load/secrets.rs
index 27008e54c..0a8f10eed 100644
--- a/src/openhuman/config/schema/load/secrets.rs
+++ b/src/openhuman/config/schema/load/secrets.rs
@@ -1,7 +1,29 @@
 use super::super::Config;
 use anyhow::{Context, Result};
 use std::path::Path;
+use std::sync::atomic::{AtomicBool, Ordering};
 
+/// Set whenever a legacy `enc:` (XOR) secret is force-migrated to `enc2:`
+/// during a `decrypt_config_secrets` pass. The flag is scoped to a single pass:
+/// `decrypt_config_secrets` clears it on entry and reads (and clears) it on exit
+/// so the caller can persist the upgraded config (audit C8). The worst case
+/// under a (rare) concurrent load is an extra, idempotent `config.save()` — the
+/// re-encryption is a no-op once values are already `enc2:`, so an occasional
+/// spurious save is harmless and never loses data.
+fn migration_flag() -> &'static AtomicBool {
+    static MIGRATED: AtomicBool = AtomicBool::new(false);
+    &MIGRATED
+}
+
+/// Decrypt one optional secret in place.
+///
+/// When the stored value uses the legacy, insecure `enc:` (XOR) format this
+/// performs a **forced one-time migration**: the field is decrypted via
+/// `decrypt_and_migrate` (which rewrites it to the `enc2:` / ChaCha20-Poly1305
+/// format) and the process-wide migration flag is raised so the caller can
+/// persist the upgraded config back to disk. This stops legacy XOR ciphertext
+/// from persisting indefinitely (see audit C8). Reading existing `enc:` values
+/// still succeeds throughout the migration.
 fn decrypt_optional_secret(
     store: &crate::openhuman::keyring::SecretStore,
     value: &mut Option<String>,
@@ -9,8 +31,19 @@ fn decrypt_optional_secret(
 ) -> Result<()> {
     if let Some(raw) = value.clone() {
         if crate::openhuman::keyring::SecretStore::is_encrypted(&raw) {
-            match store.decrypt(&raw) {
-                Ok(plaintext) => *value = Some(plaintext),
+            // Legacy `enc:` values are migrated to `enc2:` on read so they are
+            // rewritten on the next config save instead of lingering forever.
+            match store.decrypt_and_migrate(&raw) {
+                Ok((plaintext, migrated)) => {
+                    if migrated.is_some() {
+                        log::warn!(
+                            "[security][config] migrated legacy enc: secret '{field_name}' \
+                             to enc2: (ChaCha20-Poly1305); config will be re-saved to persist"
+                        );
+                        migration_flag().store(true, Ordering::Relaxed);
+                    }
+                    *value = Some(plaintext);
+                }
                 Err(e) => {
                     // Decryption key is inaccessible (e.g. rotated, keyring reset, or
                     // migrated across machines). Clear the field so config loads
@@ -54,10 +87,17 @@ fn encrypt_optional_secret(
 /// Called during config load when `secrets.encrypt` is true. Only decrypts
 /// values that have the `enc:` or `enc2:` prefix; plaintext values are
 /// returned as-is. This is a no-op when encryption is disabled.
-pub(super) fn decrypt_config_secrets(config: &mut Config, openhuman_dir: &Path) -> Result<()> {
+///
+/// Returns `true` if any field used the legacy, insecure `enc:` format and was
+/// force-migrated to `enc2:` during this pass. The caller should persist the
+/// config (e.g. `config.save()`) when this is `true` so the upgraded ciphertext
+/// is written to disk and the legacy XOR value stops persisting (audit C8).
+pub(super) fn decrypt_config_secrets(config: &mut Config, openhuman_dir: &Path) -> Result<bool> {
     if !config.secrets.encrypt {
-        return Ok(());
+        return Ok(false);
     }
+    // Reset the per-pass migration flag before decrypting any field.
+    migration_flag().store(false, Ordering::Relaxed);
     let store = crate::openhuman::keyring::SecretStore::new(openhuman_dir, true);
 
     decrypt_optional_secret(&store, &mut config.api_key, "api_key")?;
@@ -145,7 +185,7 @@ pub(super) fn decrypt_config_secrets(config: &mut Config, openhuman_dir: &Path)
         qq.app_secret = tok.unwrap_or_default();
     }
 
-    Ok(())
+    Ok(migration_flag().swap(false, Ordering::Relaxed))
 }
 
 /// Encrypt all secret fields in the configuration before writing to disk.
diff --git a/src/openhuman/inference/provider/reliable.rs b/src/openhuman/inference/provider/reliable.rs
index a098d4839..5dae660c0 100644
--- a/src/openhuman/inference/provider/reliable.rs
+++ b/src/openhuman/inference/provider/reliable.rs
@@ -8,6 +8,30 @@ use std::collections::HashMap;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::time::Duration;
 
+/// Extract an HTTP `4xx` status code from an error message, but only when it
+/// appears in a *structured* position — never from arbitrary digit runs in
+/// free text (audit C10). Recognised positions:
+///
+/// - the documented provider envelope `"… API error (<status>): …"`
+///   (e.g. `"OpenAI API error (401 Unauthorized): …"`),
+/// - an explicit `HTTP <status>` marker,
+/// - a `status: <status>` / `status <status>` field,
+/// - a status code that *leads* the message (e.g. `"404 Not Found"`).
+///
+/// Returns the matched code (always in `400..=499`) or `None`.
+fn structured_http_4xx(msg: &str) -> Option<u16> {
+    static RE: std::sync::OnceLock<regex::Regex> = std::sync::OnceLock::new();
+    let re = RE.get_or_init(|| {
+        // (?i) case-insensitive; capture the 4xx in any one of the structured
+        // anchors. `\A` matches start-of-string for the leading-status form.
+        regex::Regex::new(r"(?i)(?:\(|HTTP\s+|status[:\s]+|\A)(4\d\d)\b")
+            .expect("static is_non_retryable 4xx regex is valid")
+    });
+    re.captures(msg)
+        .and_then(|c| c.get(1))
+        .and_then(|m| m.as_str().parse::<u16>().ok())
+}
+
 /// Check if an error is non-retryable (client errors that won't resolve with retries).
 fn is_non_retryable(err: &anyhow::Error) -> bool {
     if is_context_window_exceeded(err) {
@@ -27,12 +51,14 @@ fn is_non_retryable(err: &anyhow::Error) -> bool {
             return status.is_client_error() && code != 429 && code != 408;
         }
     }
-    for word in msg.split(|c: char| !c.is_ascii_digit()) {
-        if let Ok(code) = word.parse::<u16>() {
-            if (400..500).contains(&code) {
-                return code != 429 && code != 408;
-            }
-        }
+    // Don't infer an HTTP status from *any* free-text digit run — strings like
+    // "took 450ms" (→450) or model ids like "gpt-4-0409" (→409) would be
+    // misclassified as permanent client errors and short-circuit retries
+    // (audit C10). Match only a 4xx code in a *structured* position: the
+    // documented `… API error (<status>): …` envelope, an `HTTP <status>` /
+    // `status: <status>` marker, or a status that leads the message.
+    if let Some(code) = structured_http_4xx(&msg) {
+        return code != 429 && code != 408;
     }
 
     let msg_lower = msg.to_lowercase();
@@ -330,7 +356,13 @@ fn format_failure_aggregate(
 
 /// Provider wrapper with retry, fallback, auth rotation, and model failover.
 pub struct ReliableProvider {
-    providers: Vec<(String, Box<dyn Provider>)>,
+    /// Stored behind `Arc` (not `Box`) so the streaming failover path can hand
+    /// owned, `'static` provider handles to the consumer task and create
+    /// candidate streams *lazily* — issuing each upstream request only when the
+    /// previous candidate has actually failed (see `stream_chat_with_system`).
+    /// The public `new` constructor still accepts `Box<dyn Provider>`; the
+    /// conversion happens internally so callers are unaffected.
+    providers: Vec<(String, std::sync::Arc<dyn Provider>)>,
     max_retries: u32,
     base_backoff_ms: u64,
     /// Extra API keys for rotation (index tracks round-robin position).
@@ -347,7 +379,10 @@ impl ReliableProvider {
         base_backoff_ms: u64,
     ) -> Self {
         Self {
-            providers,
+            providers: providers
+                .into_iter()
+                .map(|(name, p)| (name, std::sync::Arc::from(p)))
+                .collect(),
             max_retries,
             base_backoff_ms: base_backoff_ms.max(50),
             api_keys: Vec::new(),
@@ -1006,25 +1041,27 @@ impl Provider for ReliableProvider {
         let model_chain: Vec<String> = models.into_iter().map(|m| m.to_string()).collect();
         let base_backoff_ms = self.base_backoff_ms;
 
-        // Collect provider streams lazily inside the task — we need owned data
-        // Provider trait is object-safe, so we call stream_chat_with_system per attempt
-        // We need to pre-create all possible streams since Provider is behind &self
-        // Instead, collect the streams for each provider+model combo upfront
-        let mut candidate_streams: Vec<(
-            String,
-            String,
-            stream::BoxStream<'static, StreamResult<StreamChunk>>,
-        )> = Vec::new();
+        // Capture only owned `(provider_name, provider, model)` *tuples* up-front
+        // — NOT the streams themselves. The provider impl spawns the upstream
+        // HTTP POST the instant a stream is created, so eagerly building the
+        // full provider×model product here would fire every fallback request
+        // at once (duplicate billing/side-effects). Instead we clone the
+        // `Arc<dyn Provider>` handles and call `stream_chat_with_system` lazily
+        // inside the consumer task, immediately before each candidate is tried
+        // — mirroring the sequential non-streaming paths. (audit C2)
+        //
+        // `system_prompt` / `message` are borrowed from the caller and the
+        // spawned task is `'static`, so own them here.
+        let system_prompt_owned: Option<String> = system_prompt.map(|s| s.to_string());
+        let message_owned: String = message.to_string();
+        let mut candidates: Vec<(String, std::sync::Arc<dyn Provider>, String)> = Vec::new();
         for current_model in &model_chain {
             for (provider_name, provider) in &streaming_providers {
-                let s = provider.stream_chat_with_system(
-                    system_prompt,
-                    message,
-                    current_model,
-                    temperature,
-                    options,
-                );
-                candidate_streams.push(((*provider_name).clone(), current_model.clone(), s));
+                candidates.push((
+                    (*provider_name).clone(),
+                    std::sync::Arc::clone(provider),
+                    current_model.clone(),
+                ));
             }
         }
 
@@ -1032,11 +1069,24 @@ impl Provider for ReliableProvider {
         let max_retries = self.max_retries;
 
         tokio::spawn(async move {
-            for (provider_name, current_model, mut candidate_stream) in candidate_streams {
+            for (provider_name, provider, current_model) in candidates {
                 let mut backoff_ms = base_backoff_ms;
                 let mut attempts = 0u32;
 
                 loop {
+                    // Create (and thereby fire) the candidate stream lazily here,
+                    // immediately before we attempt it. On a retryable failure we
+                    // re-create it on the next loop iteration rather than
+                    // re-polling the previous, already-exhausted stream (which
+                    // only yields `None` after its single error). (audit C2/C6)
+                    let mut candidate_stream = provider.stream_chat_with_system(
+                        system_prompt_owned.as_deref(),
+                        &message_owned,
+                        &current_model,
+                        temperature,
+                        options,
+                    );
+
                     match candidate_stream.next().await {
                         Some(Ok(chunk)) => {
                             // First chunk succeeded — commit to this stream
@@ -1069,7 +1119,8 @@ impl Provider for ReliableProvider {
                             attempts += 1;
                             tokio::time::sleep(Duration::from_millis(backoff_ms)).await;
                             backoff_ms = (backoff_ms.saturating_mul(2)).min(10_000);
-                            // Continue inner loop — stream may yield more items
+                            // Re-create the candidate stream on the next iteration.
+                            continue;
                         }
                         None => {
                             // Stream exhausted without success
diff --git a/src/openhuman/inference/provider/reliable_tests.rs b/src/openhuman/inference/provider/reliable_tests.rs
index c7524c1ad..f19e3bf56 100644
--- a/src/openhuman/inference/provider/reliable_tests.rs
+++ b/src/openhuman/inference/provider/reliable_tests.rs
@@ -221,6 +221,40 @@ fn non_retryable_detects_common_patterns() {
     )));
 }
 
+// C10: a 4xx-looking digit run that appears in *free text* (latency figures,
+// model ids, token counts) must NOT be inferred as a permanent HTTP client
+// error — that wrongly short-circuits retries/fallback for transient failures.
+#[test]
+fn non_retryable_ignores_free_text_digit_runs() {
+    // "450" here is a latency figure, not a 450 status.
+    assert!(
+        !is_non_retryable(&anyhow::anyhow!("upstream took 450ms to respond, retrying")),
+        "latency figures must not be read as an HTTP status"
+    );
+    // "0409" embedded in a model id used to scan to 409.
+    assert!(
+        !is_non_retryable(&anyhow::anyhow!("gpt-4-0409 returned an empty completion")),
+        "model-id digits must not be read as an HTTP status"
+    );
+    // A bare 4xx-shaped token mid-sentence (not in a structured position) is
+    // also ignored now.
+    assert!(
+        !is_non_retryable(&anyhow::anyhow!(
+            "received 412 partial bytes before connection reset"
+        )),
+        "mid-text digit runs must not be read as an HTTP status"
+    );
+    // Sanity: the structured envelope is still classified as non-retryable.
+    assert!(
+        is_non_retryable(&anyhow::anyhow!(
+            "custom_openai API error (403 Forbidden): nope"
+        )),
+        "the documented (<status>) envelope must still be detected"
+    );
+    // Sanity: a leading status (no envelope) is still detected.
+    assert!(is_non_retryable(&anyhow::anyhow!("404 Not Found")));
+}
+
 #[tokio::test]
 async fn context_window_error_aborts_retries_and_model_fallbacks() {
     let calls = Arc::new(AtomicUsize::new(0));
@@ -418,6 +452,161 @@ async fn session_expired_aborts_retries_streaming() {
     );
 }
 
+/// Streaming mock whose stream fails with a *retryable* `StreamError` for the
+/// first `fail_until` creations and then yields a single successful chunk. Each
+/// stream is mpsc-like (exhausts after one item), exactly like the real
+/// provider impl — so a retry that re-polls the same dead stream would see
+/// `None` and give up. `stream_calls` records how many times a stream was
+/// created, the signal used to prove lazy creation (audit C2) and
+/// recreate-on-retry (audit C6).
+struct StreamingRetryMock {
+    stream_calls: Arc<AtomicUsize>,
+    fail_until: usize,
+}
+
+#[async_trait]
+impl Provider for StreamingRetryMock {
+    async fn chat_with_system(
+        &self,
+        _system_prompt: Option<&str>,
+        _message: &str,
+        _model: &str,
+        _temperature: f64,
+    ) -> anyhow::Result<String> {
+        anyhow::bail!("unused")
+    }
+
+    async fn chat_with_history(
+        &self,
+        _messages: &[ChatMessage],
+        _model: &str,
+        _temperature: f64,
+    ) -> anyhow::Result<String> {
+        anyhow::bail!("unused")
+    }
+
+    fn supports_streaming(&self) -> bool {
+        true
+    }
+
+    fn stream_chat_with_system(
+        &self,
+        _system_prompt: Option<&str>,
+        _message: &str,
+        _model: &str,
+        _temperature: f64,
+        _options: StreamOptions,
+    ) -> futures_util::stream::BoxStream<'static, StreamResult<StreamChunk>> {
+        use futures_util::{stream, StreamExt};
+        // The Nth stream creation (1-based) fails if N <= fail_until, else
+        // succeeds. Firing the HTTP request happens *here*, so counting
+        // creations is the proxy for "requests issued".
+        let n = self.stream_calls.fetch_add(1, Ordering::SeqCst) + 1;
+        let succeed = n > self.fail_until;
+        stream::once(async move {
+            if succeed {
+                Ok(StreamChunk::delta("hello"))
+            } else {
+                // A generic provider error — retryable per
+                // is_stream_error_non_retryable.
+                Err(StreamError::Provider("transient upstream blip".to_string()))
+            }
+        })
+        .boxed()
+    }
+}
+
+/// C2: streaming failover must NOT pre-fire every provider×model stream. With a
+/// 2-model fallback chain and a provider that succeeds on the first attempt,
+/// only ONE stream may be created (the winning candidate) — not the full
+/// cartesian product.
+#[tokio::test]
+async fn streaming_does_not_prefire_all_candidates() {
+    use futures_util::StreamExt;
+
+    let stream_calls = Arc::new(AtomicUsize::new(0));
+    let mut fallbacks = HashMap::new();
+    fallbacks.insert(
+        "model-a".to_string(),
+        vec!["model-b".to_string(), "model-c".to_string()],
+    );
+
+    let provider = ReliableProvider::new(
+        vec![(
+            "p".into(),
+            Box::new(StreamingRetryMock {
+                stream_calls: Arc::clone(&stream_calls),
+                fail_until: 0, // succeed immediately
+            }),
+        )],
+        3,
+        1,
+    )
+    .with_model_fallbacks(fallbacks);
+
+    let mut stream =
+        provider.stream_chat_with_system(None, "hi", "model-a", 0.0, StreamOptions::new(true));
+
+    let mut chunks = Vec::new();
+    while let Some(item) = stream.next().await {
+        if let Ok(chunk) = item {
+            chunks.push(chunk.delta);
+        }
+    }
+
+    assert_eq!(chunks, vec!["hello".to_string()]);
+    assert_eq!(
+        stream_calls.load(Ordering::SeqCst),
+        1,
+        "only the winning candidate may create a stream; the rest must stay lazy (C2)"
+    );
+}
+
+/// C6: a retryable streaming failure must RE-CREATE the candidate stream on the
+/// next attempt rather than re-poll the already-exhausted one. With
+/// `fail_until = 2` and `max_retries = 3`, the same provider/model is attempted
+/// up to 4 times; creations 1 and 2 fail, creation 3 succeeds. If the retry
+/// loop re-polled the dead stream instead of recreating it, we'd only ever see
+/// a single creation and the call would fail.
+#[tokio::test]
+async fn streaming_retry_recreates_stream() {
+    use futures_util::StreamExt;
+
+    let stream_calls = Arc::new(AtomicUsize::new(0));
+    let provider = ReliableProvider::new(
+        vec![(
+            "p".into(),
+            Box::new(StreamingRetryMock {
+                stream_calls: Arc::clone(&stream_calls),
+                fail_until: 2,
+            }),
+        )],
+        3,
+        1,
+    );
+
+    let mut stream =
+        provider.stream_chat_with_system(None, "hi", "reasoning-v1", 0.0, StreamOptions::new(true));
+
+    let mut chunks = Vec::new();
+    while let Some(item) = stream.next().await {
+        if let Ok(chunk) = item {
+            chunks.push(chunk.delta);
+        }
+    }
+
+    assert_eq!(
+        chunks,
+        vec!["hello".to_string()],
+        "retry must eventually recover once the recreated stream succeeds (C6)"
+    );
+    assert_eq!(
+        stream_calls.load(Ordering::SeqCst),
+        3,
+        "each retry attempt must recreate the candidate stream (C6), not re-poll the dead one"
+    );
+}
+
 #[tokio::test]
 async fn aggregated_error_marks_non_retryable_model_mismatch_with_details() {
     let calls = Arc::new(AtomicUsize::new(0));
diff --git a/src/openhuman/inference/voice/streaming.rs b/src/openhuman/inference/voice/streaming.rs
index 1d0368c7f..b6f2915b2 100644
--- a/src/openhuman/inference/voice/streaming.rs
+++ b/src/openhuman/inference/voice/streaming.rs
@@ -16,11 +16,15 @@
 //! # Security notes
 //!
 //! ## Authentication
-//! `GET /ws/dictation` is intentionally exempt from Bearer-token authentication because
-//! the browser WebSocket API cannot set arbitrary request headers on upgrade. The correct
-//! auth mechanism is a separate maintainer decision; see `src/core/auth.rs` for the
-//! documented exemption. Do NOT add a Bearer-header check here — it will not work from
-//! browsers and the design decision is tracked in issue #1924.
+//! `GET /ws/dictation` is authenticated at the upgrade boundary (C4 / issue #1924).
+//! The browser WebSocket API cannot set arbitrary request headers on upgrade, so the
+//! check lives in `dictation_ws_handler` (`src/core/jsonrpc.rs`), not here: it requires
+//! the per-process core bearer via `Authorization: Bearer <token>` (native callers) or
+//! `?token=<token>` (browser clients), plus the same origin allowlist Socket.IO enforces,
+//! and rejects the upgrade with 401/403 before this function runs. Do NOT add a
+//! Bearer-header check in this function — by the time `handle_dictation_ws` is reached the
+//! upgrade has already been authenticated, and a header check here would not work from
+//! browsers anyway.
 //!
 //! ## Memory cap
 //! The full-audio accumulation buffer (`full_audio_buf`) is bounded by
diff --git a/src/openhuman/keyring/encrypted_store.rs b/src/openhuman/keyring/encrypted_store.rs
index 0d25e202c..f2930116a 100644
--- a/src/openhuman/keyring/encrypted_store.rs
+++ b/src/openhuman/keyring/encrypted_store.rs
@@ -20,8 +20,11 @@
 // For sovereign users who prefer plaintext, `secrets.encrypt = false` disables this.
 //
 // Migration: values with the legacy `enc:` prefix (XOR cipher) are decrypted
-// using the old algorithm for backward compatibility. New encryptions always
-// produce `enc2:` (ChaCha20-Poly1305).
+// using the old algorithm for backward compatibility, but the config loader
+// force-migrates them to `enc2:` on read (`decrypt_and_migrate`) and persists
+// the upgrade so the insecure ciphertext never lingers on disk (audit C8). The
+// legacy decode path logs a loud security warning every time it runs. New
+// encryptions always produce `enc2:` (ChaCha20-Poly1305).
 
 use anyhow::{Context, Result};
 use chacha20poly1305::aead::{Aead, KeyInit, OsRng};
@@ -31,6 +34,7 @@ use std::fs;
 use std::path::{Path, PathBuf};
 use std::sync::{Mutex, OnceLock};
 use std::time::Duration;
+use zeroize::Zeroizing;
 
 use super::crypto;
 
@@ -160,7 +164,22 @@ impl SecretStore {
     }
 
     /// Decrypt using legacy XOR cipher (insecure, for backward compatibility only).
+    ///
+    /// This is the single choke-point for the insecure `enc:` format, so it logs
+    /// a loud security warning every time it runs. The repeating-key XOR is
+    /// unauthenticated and leaks the master key to anyone who knows (or can guess
+    /// the structure of) the plaintext — e.g. `xoxb-`/`sk-` token prefixes give
+    /// `key[i] = ct[i] XOR pt[i]`. Callers on the read path should prefer
+    /// [`decrypt_and_migrate`](Self::decrypt_and_migrate) so the value is rewritten
+    /// to `enc2:` and the legacy ciphertext stops persisting on disk.
     fn decrypt_legacy_xor(&self, hex_str: &str) -> Result<String> {
+        log::warn!(
+            "[security] decrypting legacy XOR-encrypted secret (enc: prefix). \
+             This format is INSECURE (unauthenticated repeating-key XOR; known-plaintext \
+             recovers the master key) and must be migrated to enc2: (ChaCha20-Poly1305). \
+             It will be removed in a future release — re-save your config or settings to \
+             force migration."
+        );
         let ciphertext = hex_decode(hex_str)
             .context("Failed to decode legacy encrypted secret (corrupt hex)")?;
         let key = self.load_or_create_key()?;
@@ -187,7 +206,7 @@ impl SecretStore {
         keyring_user_id_from_dir(self.key_path.parent().unwrap_or_else(|| Path::new(".")))
     }
 
-    fn load_or_create_key_from_keyring(&self) -> Result<Vec<u8>> {
+    fn load_or_create_key_from_keyring(&self) -> Result<Zeroizing<Vec<u8>>> {
         let user_id = self.keyring_user_id();
         match crate::openhuman::keyring::migrate_from_file(
             &user_id,
@@ -228,7 +247,11 @@ impl SecretStore {
     /// The decoded key is cached process-wide keyed by `key_path`, so repeated
     /// callers (e.g. every `app_state_snapshot` poll) hit memory instead of
     /// disk/keychain lookup.
-    fn load_or_create_key(&self) -> Result<Vec<u8>> {
+    ///
+    /// The key bytes are wrapped in [`Zeroizing`] so every copy — the returned
+    /// value, the cache entry, and any intermediate buffers — is wiped from
+    /// memory on drop rather than lingering in the heap/swap/core-dumps.
+    fn load_or_create_key(&self) -> Result<Zeroizing<Vec<u8>>> {
         // Normalize the path once so all callers share the same cache slot
         // regardless of how `key_path` was spelled (relative vs absolute,
         // symlinks, case-variants on Windows).
@@ -462,18 +485,20 @@ fn normalize_cache_path(path: &Path) -> PathBuf {
 /// transiently inaccessible (AV scanners holding a handle), and re-reading
 /// turned that transient failure into a perma-failure for every subsequent
 /// RPC call.
-fn key_cache() -> &'static Mutex<HashMap<PathBuf, Vec<u8>>> {
-    static CACHE: OnceLock<Mutex<HashMap<PathBuf, Vec<u8>>>> = OnceLock::new();
+fn key_cache() -> &'static Mutex<HashMap<PathBuf, Zeroizing<Vec<u8>>>> {
+    static CACHE: OnceLock<Mutex<HashMap<PathBuf, Zeroizing<Vec<u8>>>>> = OnceLock::new();
     CACHE.get_or_init(|| Mutex::new(HashMap::new()))
 }
 
-fn cached_key(path: &Path) -> Option<Vec<u8>> {
+fn cached_key(path: &Path) -> Option<Zeroizing<Vec<u8>>> {
     key_cache().lock().ok()?.get(path).cloned()
 }
 
 fn cache_key(path: &Path, key: &[u8]) {
     if let Ok(mut cache) = key_cache().lock() {
-        cache.insert(path.to_path_buf(), key.to_vec());
+        // Stored as `Zeroizing` so the cached copy is wiped from memory when the
+        // entry is removed (e.g. via `clear_cached_key`) or the process exits.
+        cache.insert(path.to_path_buf(), Zeroizing::new(key.to_vec()));
     }
 }
 
@@ -621,12 +646,12 @@ fn xor_cipher(data: &[u8], key: &[u8]) -> Vec<u8> {
         .collect()
 }
 
-fn generate_random_key() -> Vec<u8> {
-    crypto::generate_random_bytes(KEY_LEN)
+fn generate_random_key() -> Zeroizing<Vec<u8>> {
+    Zeroizing::new(crypto::generate_random_bytes(KEY_LEN))
 }
 
-fn decode_key_hex(hex_key: &str) -> Result<Vec<u8>> {
-    let key = hex_decode(hex_key).context("Secret key file is corrupt")?;
+fn decode_key_hex(hex_key: &str) -> Result<Zeroizing<Vec<u8>>> {
+    let key = Zeroizing::new(hex_decode(hex_key).context("Secret key file is corrupt")?);
     anyhow::ensure!(
         key.len() == KEY_LEN,
         "Secret key file has wrong length: expected {KEY_LEN} bytes, got {}",
diff --git a/src/openhuman/keyring/encrypted_store_tests.rs b/src/openhuman/keyring/encrypted_store_tests.rs
index 342642c2b..5cba576d5 100644
--- a/src/openhuman/keyring/encrypted_store_tests.rs
+++ b/src/openhuman/keyring/encrypted_store_tests.rs
@@ -784,6 +784,26 @@ fn generate_random_key_correct_length() {
     assert_eq!(key.len(), KEY_LEN);
 }
 
+#[test]
+fn master_key_is_zeroizing_and_cache_stable() {
+    // Regression for audit C9: the master key is returned wrapped in
+    // `zeroize::Zeroizing` (wiped on drop) and the cached copy is the same
+    // bytes on a subsequent load (cache hit). The static type assertion below
+    // fails to compile if the return type stops being `Zeroizing`.
+    let tmp = TempDir::new().unwrap();
+    let store = SecretStore::new(tmp.path(), true);
+
+    let key: zeroize::Zeroizing<Vec<u8>> = store.load_or_create_key().unwrap();
+    assert_eq!(key.len(), KEY_LEN);
+
+    // Second load must return identical key bytes from the process-wide cache.
+    let key2 = store.load_or_create_key().unwrap();
+    assert_eq!(
+        &*key, &*key2,
+        "cached master key must be stable across loads"
+    );
+}
+
 #[test]
 fn generate_random_key_not_all_zeros() {
     let key = generate_random_key();
diff --git a/src/openhuman/memory_store/chunks/connection.rs b/src/openhuman/memory_store/chunks/connection.rs
index 835edb24a..486d1ee60 100644
--- a/src/openhuman/memory_store/chunks/connection.rs
+++ b/src/openhuman/memory_store/chunks/connection.rs
@@ -116,6 +116,9 @@ struct CircuitBreaker {
     consecutive_failures: AtomicU32,
     tripped: AtomicBool,
     last_trip: PMutex<Option<Instant>>,
+    /// Set once a `SystemStartup` mark has been published for this path so a
+    /// fresh boot reports a real status without re-emitting on every open.
+    startup_emitted: AtomicBool,
 }
 
 impl CircuitBreaker {
@@ -124,13 +127,27 @@ impl CircuitBreaker {
             consecutive_failures: AtomicU32::new(0),
             tripped: AtomicBool::new(false),
             last_trip: PMutex::new(None),
+            startup_emitted: AtomicBool::new(false),
         }
     }
 
-    fn record_success(&self) {
+    /// Records a successful init. Returns `true` if this call cleared a
+    /// previously-tripped breaker (i.e. a transition back to healthy that the
+    /// caller should announce on the bus). Returns `false` for the steady-state
+    /// case where the breaker was already untripped, so we don't spam a
+    /// `HealthChanged{healthy:true}` event on every successful call.
+    fn record_success(&self) -> bool {
         self.consecutive_failures.store(0, Ordering::Relaxed);
-        self.tripped.store(false, Ordering::Relaxed);
         *self.last_trip.lock() = None;
+        // `swap` reports the prior value: `true` means we just transitioned
+        // from tripped → untripped, which is the recovery edge to announce.
+        self.tripped.swap(false, Ordering::Relaxed)
+    }
+
+    /// Returns `true` exactly once per breaker — on the first successful open —
+    /// so the caller emits a single `SystemStartup` mark for this path.
+    fn mark_startup_emitted(&self) -> bool {
+        !self.startup_emitted.swap(true, Ordering::Relaxed)
     }
 
     /// Records one more failure. Returns `true` if this call just tripped the
@@ -447,9 +464,42 @@ pub(crate) fn get_or_init_connection(config: &Config) -> Result<Arc<PMutex<Conne
                 .connections
                 .lock()
                 .insert(db_path.clone(), Arc::clone(&arc_conn));
-            // Reset any prior failure counter now that init succeeded.
-            if let Some(breaker) = conn_cache().breakers.lock().get(&db_path) {
-                breaker.record_success();
+            // Reset any prior failure counter now that init succeeded. Use (or
+            // lazily create) the persistent breaker so a clean first boot still
+            // has somewhere to record the one-shot startup mark.
+            let breaker = {
+                let mut guard = conn_cache().breakers.lock();
+                guard
+                    .entry(db_path.clone())
+                    .or_insert_with(|| Arc::new(CircuitBreaker::new()))
+                    .clone()
+            };
+            // Emit a one-time `SystemStartup` so a fresh boot reports a real
+            // status for `memory_tree_db` instead of "unknown" until the first
+            // failure. Fires once per path for the process lifetime.
+            if breaker.mark_startup_emitted() {
+                let _ = crate::core::event_bus::publish_global(
+                    crate::core::event_bus::DomainEvent::SystemStartup {
+                        component: "memory_tree_db".to_string(),
+                    },
+                );
+            }
+            // Only announce recovery on the transition back to healthy — i.e.
+            // when the breaker had previously tripped (driving `/health` to a
+            // permanent 503). Steady-state successes stay silent so we don't
+            // spam a `HealthChanged{healthy:true}` event on every call.
+            if breaker.record_success() {
+                log::info!(
+                    "[memory_tree] circuit breaker recovered for {}: DB init succeeded after a prior trip",
+                    db_path.display()
+                );
+                let _ = crate::core::event_bus::publish_global(
+                    crate::core::event_bus::DomainEvent::HealthChanged {
+                        component: "memory_tree_db".to_string(),
+                        healthy: true,
+                        message: None,
+                    },
+                );
             }
             log::debug!("[memory_tree] DB connection cached and ready");
             Ok(arc_conn)
@@ -546,3 +596,42 @@ pub fn with_connection<T>(config: &Config, f: impl FnOnce(&Connection) -> Result
     let guard = conn_arc.lock();
     f(&guard)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// `record_success` must only report a recovery transition (`true`) when
+    /// it actually clears a tripped breaker — the signal `get_or_init_connection`
+    /// uses to publish `HealthChanged{healthy:true}` exactly once instead of on
+    /// every successful call (C1).
+    #[test]
+    fn record_success_announces_only_on_trip_to_healthy_transition() {
+        let cb = CircuitBreaker::new();
+
+        // Untripped breaker: a success is steady-state, not a transition.
+        assert!(!cb.record_success());
+
+        // Trip the breaker by crossing the failure threshold.
+        let mut tripped = false;
+        for _ in 0..CB_THRESHOLD {
+            tripped = cb.record_failure();
+        }
+        assert!(tripped, "breaker should trip at CB_THRESHOLD failures");
+
+        // First success after a trip is the recovery edge → announce once.
+        assert!(cb.record_success());
+        // Subsequent successes are steady-state → stay silent.
+        assert!(!cb.record_success());
+    }
+
+    /// `mark_startup_emitted` must fire exactly once so a fresh boot emits a
+    /// single `SystemStartup` mark for `memory_tree_db` (C1).
+    #[test]
+    fn startup_mark_fires_exactly_once() {
+        let cb = CircuitBreaker::new();
+        assert!(cb.mark_startup_emitted());
+        assert!(!cb.mark_startup_emitted());
+        assert!(!cb.mark_startup_emitted());
+    }
+}
diff --git a/src/openhuman/memory_store/content/read.rs b/src/openhuman/memory_store/content/read.rs
index aafe96731..01c4c225c 100644
--- a/src/openhuman/memory_store/content/read.rs
+++ b/src/openhuman/memory_store/content/read.rs
@@ -1,11 +1,74 @@
 //! Read and verify chunk and summary `.md` files from the content store.
 
-use std::path::Path;
+use std::path::{Component, Path, PathBuf};
 
 use super::atomic::sha256_hex;
 use super::compose::split_front_matter;
 use crate::openhuman::memory::util::redact::redact;
 
+/// Resolve a DB-stored relative forward-slash path against `content_root`,
+/// rejecting any traversal (`..`), absolute, or non-normal component.
+///
+/// The `raw_refs` / `content_path` values are treated as **untrusted** at the
+/// read boundary: although the write path slugifies/sanitizes them, a future
+/// ingest source or DB tamper could store `../../etc/passwd` and turn this
+/// reader into an arbitrary file-disclosure primitive that feeds the LLM
+/// context. We therefore (1) reject any `..`/absolute/prefix component before
+/// touching disk and (2) — when the target exists — canonicalize the resolved
+/// path and assert it stays under the canonicalized `content_root`.
+fn resolve_within_content_root(content_root: &Path, rel_path: &str) -> anyhow::Result<PathBuf> {
+    // Reject absolute inputs outright. A leading `/` (or a Windows drive/UNC
+    // prefix) would otherwise split into an empty leading component that gets
+    // silently skipped, treating `/etc/passwd` as a relative path under the
+    // content root rather than flagging the obvious traversal attempt.
+    if Path::new(rel_path).is_absolute() {
+        return Err(anyhow::anyhow!(
+            "[content_store::read] rejected absolute path in path_hash={}",
+            redact(rel_path),
+        ));
+    }
+
+    let mut abs = content_root.to_path_buf();
+    for component in rel_path.split('/') {
+        // Skip empty components from leading/double/trailing slashes.
+        if component.is_empty() || component == "." {
+            continue;
+        }
+        // Reject anything that is not a plain file/dir name: `..`, absolute
+        // roots, Windows prefixes, etc.
+        match Path::new(component).components().next() {
+            Some(Component::Normal(_)) => abs.push(component),
+            _ => {
+                return Err(anyhow::anyhow!(
+                    "[content_store::read] rejected unsafe path component in path_hash={}",
+                    redact(rel_path),
+                ));
+            }
+        }
+    }
+
+    // Defense in depth: if the file exists, canonicalize and confirm
+    // containment. (canonicalize requires the path to exist, so this is a
+    // no-op for not-yet-created files — the component check above already
+    // blocks traversal in that case.)
+    if abs.exists() {
+        let canon_root = content_root
+            .canonicalize()
+            .unwrap_or_else(|_| content_root.to_path_buf());
+        let canon_abs = abs
+            .canonicalize()
+            .map_err(|e| anyhow::anyhow!("[content_store::read] canonicalize failed: {e}"))?;
+        if !canon_abs.starts_with(&canon_root) {
+            return Err(anyhow::anyhow!(
+                "[content_store::read] resolved path escapes content_root for path_hash={}",
+                redact(rel_path),
+            ));
+        }
+    }
+
+    Ok(abs)
+}
+
 /// The result of reading a chunk file from disk.
 pub struct ChunkFileContents {
     /// The Markdown body (everything after the closing `---` of the front-matter).
@@ -175,14 +238,9 @@ pub fn read_chunk_body(
     }
 
     let content_root = config.memory_tree_content_root();
-    // Reconstruct the absolute path from the stored relative forward-slash path.
-    let abs_path = {
-        let mut p = content_root.clone();
-        for component in rel_path.split('/') {
-            p.push(component);
-        }
-        p
-    };
+    // Reconstruct the absolute path from the stored relative forward-slash
+    // path, rejecting any traversal and confirming containment.
+    let abs_path = resolve_within_content_root(&content_root, &rel_path)?;
 
     log::debug!(
         "[content_store::read] read_chunk_body chunk_id={} path_hash={}",
@@ -237,10 +295,20 @@ fn read_chunk_body_from_raw(
     let content_root = config.memory_tree_content_root();
     let mut parts: Vec<String> = Vec::with_capacity(refs.len());
     for r in refs {
-        let mut abs = content_root.clone();
-        for component in r.path.split('/') {
-            abs.push(component);
-        }
+        // Treat the DB-stored ref path as untrusted: reject traversal /
+        // absolute paths and confirm the resolved path stays under
+        // content_root before reading. Skip (don't fail the whole chunk) on a
+        // rejected ref, matching the best-effort policy for per-file errors.
+        let abs = match resolve_within_content_root(&content_root, &r.path) {
+            Ok(p) => p,
+            Err(e) => {
+                log::warn!(
+                    "[content_store::read] raw_ref rejected path_hash={} err={e}",
+                    redact(&r.path)
+                );
+                continue;
+            }
+        };
         let bytes = match std::fs::read(&abs) {
             Ok(b) => b,
             Err(e) => {
@@ -300,13 +368,7 @@ pub fn read_summary_body(
     let (rel_path, expected_sha256) = pointers;
 
     let content_root = config.memory_tree_content_root();
-    let abs_path = {
-        let mut p = content_root.clone();
-        for component in rel_path.split('/') {
-            p.push(component);
-        }
-        p
-    };
+    let abs_path = resolve_within_content_root(&content_root, &rel_path)?;
 
     log::debug!(
         "[content_store::read] read_summary_body summary_id={} path_hash={}",
@@ -605,6 +667,55 @@ mod tests {
         assert_eq!(body, "bcd");
     }
 
+    #[test]
+    fn read_chunk_body_from_raw_rejects_path_traversal() {
+        use crate::openhuman::memory_store::chunks::store::RawRef;
+
+        let dir = TempDir::new().unwrap();
+        let mut cfg = crate::openhuman::config::Config::default();
+        cfg.workspace_dir = dir.path().to_path_buf();
+
+        let content_root = cfg.memory_tree_content_root();
+        std::fs::create_dir_all(&content_root).unwrap();
+        std::fs::write(content_root.join("safe.txt"), "safe").unwrap();
+
+        // A secret sitting next to content_root that a traversal ref tries to
+        // reach. The traversal ref must be skipped, leaving only the safe body.
+        let outside = content_root.parent().unwrap().join("secret.txt");
+        std::fs::write(&outside, "TOP SECRET").unwrap();
+
+        let refs = vec![
+            RawRef {
+                path: "../secret.txt".into(),
+                start: 0,
+                end: None,
+            },
+            RawRef {
+                path: "safe.txt".into(),
+                start: 0,
+                end: None,
+            },
+        ];
+
+        let body = read_chunk_body_from_raw(&cfg, &refs).unwrap();
+        assert_eq!(body, "safe");
+        assert!(!body.contains("SECRET"));
+    }
+
+    #[test]
+    fn resolve_within_content_root_rejects_traversal_and_absolute() {
+        let dir = TempDir::new().unwrap();
+        let root = dir.path();
+
+        assert!(resolve_within_content_root(root, "../escape.md").is_err());
+        assert!(resolve_within_content_root(root, "a/../../escape.md").is_err());
+        assert!(resolve_within_content_root(root, "/etc/passwd").is_err());
+
+        // Safe relative paths resolve correctly.
+        let ok = resolve_within_content_root(root, "sub/dir/file.md").unwrap();
+        assert_eq!(ok, root.join("sub").join("dir").join("file.md"));
+    }
+
     #[test]
     fn read_chunk_body_roundtrips_from_staged_content_pointer() {
         let tmp = TempDir::new().unwrap();
diff --git a/src/openhuman/security/bubblewrap.rs b/src/openhuman/security/bubblewrap.rs
index 187f3314e..41232c905 100644
--- a/src/openhuman/security/bubblewrap.rs
+++ b/src/openhuman/security/bubblewrap.rs
@@ -49,8 +49,12 @@ impl Sandbox for BubblewrapSandbox {
             "/dev",
             "--proc",
             "/proc",
-            "--bind",
-            "/tmp",
+            // Private, empty /tmp inside the sandbox instead of sharing the
+            // host's read-write /tmp. Mirrors firejail.rs's `--private=home`
+            // least-privilege posture: the agent gets a scratch tmp that is
+            // discarded on exit and cannot read/overwrite other processes'
+            // host temp files, lockfiles, sockets, or staged secrets.
+            "--tmpfs",
             "/tmp",
             "--unshare-all",
             "--die-with-parent",
@@ -180,4 +184,37 @@ mod tests {
             "must include /proc mount"
         );
     }
+
+    #[test]
+    fn bubblewrap_wrap_command_uses_private_tmpfs_not_host_tmp() {
+        let sandbox = BubblewrapSandbox;
+        let mut cmd = Command::new("echo");
+        sandbox.wrap_command(&mut cmd).unwrap();
+
+        let args: Vec<String> = cmd
+            .get_args()
+            .map(|s| s.to_string_lossy().to_string())
+            .collect();
+
+        // The sandbox must mount a private tmpfs over /tmp ...
+        let tmpfs_pos = args.iter().position(|a| a == "--tmpfs");
+        assert!(
+            tmpfs_pos.is_some(),
+            "must include --tmpfs for a private /tmp"
+        );
+        assert_eq!(
+            args.get(tmpfs_pos.unwrap() + 1).map(String::as_str),
+            Some("/tmp"),
+            "--tmpfs must target /tmp"
+        );
+
+        // ... and must NOT read-write bind the host /tmp into the sandbox.
+        let has_tmp_rw_bind = args
+            .windows(3)
+            .any(|w| w[0] == "--bind" && w[1] == "/tmp" && w[2] == "/tmp");
+        assert!(
+            !has_tmp_rw_bind,
+            "must NOT bind host /tmp read-write into the sandbox"
+        );
+    }
 }
diff --git a/tests/json_rpc_e2e.rs b/tests/json_rpc_e2e.rs
index 610ca5aa7..18c21aa65 100644
--- a/tests/json_rpc_e2e.rs
+++ b/tests/json_rpc_e2e.rs
@@ -7909,10 +7909,19 @@ async fn public_paths_accessible_without_token() {
         );
     }
 
-    // Paths that bypass auth but return non-2xx for unrelated reasons
-    // (missing required query params, no WebSocket upgrade headers, etc.).
-    // The invariant is that the auth middleware does NOT reject them with 401.
-    for path in ["/auth/telegram", "/events", "/ws/dictation"] {
+    // Paths that bypass the *middleware* header check but return non-2xx for
+    // unrelated reasons (missing required query params, no WebSocket upgrade
+    // headers, etc.). The invariant here is that the auth middleware does NOT
+    // reject them with 401.
+    //
+    // NOTE: `/events` and `/ws/dictation` enforce their own credential inside
+    // the handler (bind token / bearer / `?token=`), so an unauthenticated GET
+    // to those returns 401 from the HANDLER (not the middleware). `/events`
+    // requires a `client_id` query param, so an empty request is rejected by
+    // Axum's extractor (400) before the handler's own auth runs — it stays in
+    // this `!= 401` group. `/ws/dictation` is asserted separately below now
+    // that it is authenticated at the upgrade boundary (C4 / issue #1924).
+    for path in ["/auth/telegram", "/events"] {
         let resp = client
             .get(format!("{base}{path}"))
             .send()
@@ -7921,11 +7930,26 @@ async fn public_paths_accessible_without_token() {
         assert_ne!(
             resp.status(),
             StatusCode::UNAUTHORIZED,
-            "public path {path} must not be auth-gated (got {})",
+            "public path {path} must not be auth-gated by the middleware (got {})",
             resp.status()
         );
     }
 
+    // `/ws/dictation` is now authenticated at the upgrade boundary (C4 /
+    // issue #1924): an unauthenticated request (no bearer header, no
+    // `?token=`) must be rejected with 401 by the handler before any upgrade.
+    let resp = client
+        .get(format!("{base}/ws/dictation"))
+        .send()
+        .await
+        .unwrap_or_else(|e| panic!("GET /ws/dictation: {e}"));
+    assert_eq!(
+        resp.status(),
+        StatusCode::UNAUTHORIZED,
+        "/ws/dictation must reject unauthenticated upgrades with 401 (got {})",
+        resp.status()
+    );
+
     rpc_join.abort();
 }