diff --git a/.github/workflows/release-beta.yml b/.github/workflows/release-beta.yml
index 11419c3d1..68fe52231 100644
--- a/.github/workflows/release-beta.yml
+++ b/.github/workflows/release-beta.yml
@@ -32,6 +32,9 @@ concurrency:
   group: open-design-release-beta
   cancel-in-progress: false
 
+env:
+  OPEN_DESIGN_TELEMETRY_RELAY_URL: ${{ vars.OPEN_DESIGN_TELEMETRY_RELAY_URL }}
+
 jobs:
   metadata:
     name: Prepare beta metadata
diff --git a/.github/workflows/release-stable.yml b/.github/workflows/release-stable.yml
index 192dcdd85..9e626c9c1 100644
--- a/.github/workflows/release-stable.yml
+++ b/.github/workflows/release-stable.yml
@@ -24,6 +24,9 @@ concurrency:
   group: open-design-release-stable-${{ inputs.channel }}
   cancel-in-progress: false
 
+env:
+  OPEN_DESIGN_TELEMETRY_RELAY_URL: ${{ vars.OPEN_DESIGN_TELEMETRY_RELAY_URL }}
+
 jobs:
   metadata:
     name: Prepare release metadata
diff --git a/apps/daemon/src/langfuse-trace.ts b/apps/daemon/src/langfuse-trace.ts
index b79334543..003a277e4 100644
--- a/apps/daemon/src/langfuse-trace.ts
+++ b/apps/daemon/src/langfuse-trace.ts
@@ -1,8 +1,9 @@
 // Langfuse trace forwarding for completed agent runs.
 //
-// This module is intentionally dependency-free (no `langfuse` SDK). It posts
-// a trace with nested observations to Langfuse's public ingestion endpoint when
-// a run reaches a terminal state. Without LANGFUSE_PUBLIC_KEY /
+// This module is intentionally dependency-free (no `langfuse` SDK). It builds
+// Langfuse ingestion batches for completed runs and sends them either to the
+// official Open Design telemetry relay or, for local smoke tests, directly to
+// Langfuse. Without OPEN_DESIGN_TELEMETRY_RELAY_URL or LANGFUSE_PUBLIC_KEY /
 // LANGFUSE_SECRET_KEY in the env, every entry point becomes a no-op so that
 // dev runs and forks of this open-source repo do not accidentally report.
 //
@@ -33,6 +34,7 @@ const SESSION_ID_MAX = 200; // Langfuse drops sessionIds longer than this.
 const HARD_BATCH_MAX_BYTES = 1024 * 1024;
 const DEFAULT_FETCH_TIMEOUT_MS = 20_000;
 const DEFAULT_FETCH_RETRIES = 1;
+let missingTelemetrySinkWarned = false;
 
 export interface LangfuseConfig {
   authHeader: string;
@@ -41,6 +43,17 @@ export interface LangfuseConfig {
   retries: number;
 }
 
+export type TelemetrySinkConfig =
+  | {
+      kind: 'relay';
+      relayUrl: string;
+      timeoutMs: number;
+      retries: number;
+    }
+  | ({
+      kind: 'langfuse';
+    } & LangfuseConfig);
+
 export interface RunSummary {
   runId: string;
   status: 'succeeded' | 'failed' | 'canceled';
@@ -133,7 +146,7 @@ export interface ReportContext {
 }
 
 export interface ReportRunOpts {
-  config?: LangfuseConfig | null;
+  config?: TelemetrySinkConfig | LangfuseConfig | null;
   fetchImpl?: typeof fetch;
 }
 
@@ -161,6 +174,33 @@ export function readLangfuseConfig(
   };
 }
 
+/**
+ * Resolve telemetry delivery in release-safe order: hosted relay first,
+ * direct Langfuse credentials second for local smoke tests, disabled last.
+ */
+export function readTelemetrySinkConfig(
+  env: NodeJS.ProcessEnv = process.env,
+): TelemetrySinkConfig | null {
+  const relayUrl = env.OPEN_DESIGN_TELEMETRY_RELAY_URL?.trim();
+  if (relayUrl) {
+    return {
+      kind: 'relay',
+      relayUrl: relayUrl.replace(/\/+$/, ''),
+      timeoutMs: parsePositiveInt(
+        env.OPEN_DESIGN_TELEMETRY_TIMEOUT_MS ?? env.LANGFUSE_TIMEOUT_MS,
+        DEFAULT_FETCH_TIMEOUT_MS,
+      ),
+      retries: parseNonNegativeInt(
+        env.OPEN_DESIGN_TELEMETRY_RETRIES ?? env.LANGFUSE_RETRIES,
+        DEFAULT_FETCH_RETRIES,
+      ),
+    };
+  }
+
+  const config = readLangfuseConfig(env);
+  return config == null ? null : { kind: 'langfuse', ...config };
+}
+
 function parsePositiveInt(value: string | undefined, fallback: number): number {
   if (value === undefined) return fallback;
   const parsed = Number.parseInt(value, 10);
@@ -471,21 +511,7 @@ async function postLangfuseBatch(
       // silently disappear server-side.
       const body = await response.text().catch(() => '');
       if (!body) return;
-      let parsed: unknown;
-      try {
-        parsed = JSON.parse(body);
-      } catch {
-        return;
-      }
-      const errors =
-        parsed && typeof parsed === 'object' && !Array.isArray(parsed)
-          ? (parsed as { errors?: unknown }).errors
-          : undefined;
-      if (Array.isArray(errors) && errors.length > 0) {
-        console.warn(
-          `[langfuse-trace] Per-event errors (${errors.length}): ${JSON.stringify(errors).slice(0, 500)}`,
-        );
-      }
+      warnPerEventErrors(body, 'Per-event errors');
       return;
     } catch (error) {
       if (attempt < attempts) {
@@ -498,21 +524,110 @@ async function postLangfuseBatch(
   }
 }
 
+async function postRelayBatch(
+  config: Extract<TelemetrySinkConfig, { kind: 'relay' }>,
+  body: string,
+  fetchImpl: typeof fetch,
+): Promise<void> {
+  const attempts = config.retries + 1;
+  for (let attempt = 1; attempt <= attempts; attempt += 1) {
+    try {
+      const response = await fetchImpl(config.relayUrl, {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+          'X-Open-Design-Telemetry': 'langfuse-ingestion-v1',
+        },
+        signal: AbortSignal.timeout(config.timeoutMs),
+        body,
+      });
+      if (!response.ok) {
+        const responseBody = await response.text().catch(() => '');
+        if (
+          attempt < attempts &&
+          (response.status === 429 || response.status >= 500)
+        ) {
+          await waitBeforeRetry(attempt);
+          continue;
+        }
+        console.warn(
+          `[langfuse-trace] Relay failed ${response.status}: ${responseBody.slice(0, 200)}`,
+        );
+        return;
+      }
+
+      const responseBody = await response.text().catch(() => '');
+      if (!responseBody) return;
+      warnPerEventErrors(responseBody, 'Relay per-event errors');
+      return;
+    } catch (error) {
+      if (attempt < attempts) {
+        await waitBeforeRetry(attempt);
+        continue;
+      }
+      console.warn(`[langfuse-trace] Relay fetch error: ${String(error)}`);
+      return;
+    }
+  }
+}
+
 function waitBeforeRetry(attempt: number): Promise<void> {
   return new Promise((resolve) =>
     setTimeout(resolve, Math.min(250 * attempt, 1000)),
   );
 }
 
+function normalizeTelemetrySinkConfig(
+  config: TelemetrySinkConfig | LangfuseConfig,
+): TelemetrySinkConfig {
+  if ('kind' in config) return config;
+  return { kind: 'langfuse', ...config };
+}
+
+function resolveReportConfig(
+  opts: ReportRunOpts,
+): TelemetrySinkConfig | null {
+  if (opts.config === undefined) return readTelemetrySinkConfig();
+  if (opts.config == null) return null;
+  return normalizeTelemetrySinkConfig(opts.config);
+}
+
+function warnPerEventErrors(responseBody: string, label: string): void {
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(responseBody);
+  } catch {
+    return;
+  }
+  const errors =
+    parsed && typeof parsed === 'object' && !Array.isArray(parsed)
+      ? (parsed as { errors?: unknown }).errors
+      : undefined;
+  if (Array.isArray(errors) && errors.length > 0) {
+    console.warn(
+      `[langfuse-trace] ${label} (${errors.length}): ${JSON.stringify(errors).slice(0, 500)}`,
+    );
+  }
+}
+
 export async function reportRunCompleted(
   ctx: ReportContext,
   opts: ReportRunOpts = {},
 ): Promise<void> {
   if (ctx.prefs.metrics !== true) return;
 
-  const config =
-    opts.config !== undefined ? opts.config : readLangfuseConfig();
-  if (!config) return;
+  const config = resolveReportConfig(opts);
+  if (!config) {
+    if (!missingTelemetrySinkWarned) {
+      // Warn once per daemon process; packaged config is loaded at process
+      // start, so repeated run-level warnings would only add noise.
+      missingTelemetrySinkWarned = true;
+      console.warn(
+        '[langfuse-trace] Telemetry metrics are enabled but no relay or Langfuse credentials are configured',
+      );
+    }
+    return;
+  }
 
   let batch: unknown[];
   try {
@@ -535,5 +650,9 @@ export async function reportRunCompleted(
   }
 
   const fetchImpl = opts.fetchImpl ?? globalThis.fetch;
+  if (config.kind === 'relay') {
+    await postRelayBatch(config, serialized, fetchImpl);
+    return;
+  }
   await postLangfuseBatch(config, batch, fetchImpl);
 }
diff --git a/apps/daemon/tests/langfuse-trace.test.ts b/apps/daemon/tests/langfuse-trace.test.ts
index 953643ba9..c62b8169d 100644
--- a/apps/daemon/tests/langfuse-trace.test.ts
+++ b/apps/daemon/tests/langfuse-trace.test.ts
@@ -3,9 +3,11 @@ import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import {
   buildTracePayload,
   readLangfuseConfig,
+  readTelemetrySinkConfig,
   reportRunCompleted,
   type LangfuseConfig,
   type ReportContext,
+  type TelemetrySinkConfig,
 } from '../src/langfuse-trace.js';
 
 function makeCtx(overrides: Partial<ReportContext> = {}): ReportContext {
@@ -141,6 +143,48 @@ describe('readLangfuseConfig', () => {
   });
 });
 
+describe('readTelemetrySinkConfig', () => {
+  it('prefers the Open Design telemetry relay when configured', () => {
+    const cfg = readTelemetrySinkConfig({
+      OPEN_DESIGN_TELEMETRY_RELAY_URL: 'https://telemetry.open-design.ai/api/langfuse//',
+      LANGFUSE_PUBLIC_KEY: 'pk',
+      LANGFUSE_SECRET_KEY: 'sk',
+    });
+    expect(cfg).toEqual({
+      kind: 'relay',
+      relayUrl: 'https://telemetry.open-design.ai/api/langfuse',
+      timeoutMs: 20_000,
+      retries: 1,
+    });
+  });
+
+  it('uses relay-specific timeout and retry tuning when present', () => {
+    const cfg = readTelemetrySinkConfig({
+      OPEN_DESIGN_TELEMETRY_RELAY_URL: 'https://telemetry.open-design.ai/api/langfuse',
+      OPEN_DESIGN_TELEMETRY_TIMEOUT_MS: '30000',
+      OPEN_DESIGN_TELEMETRY_RETRIES: '3',
+      LANGFUSE_TIMEOUT_MS: '1',
+      LANGFUSE_RETRIES: '0',
+    });
+    expect(cfg).toMatchObject({
+      kind: 'relay',
+      timeoutMs: 30_000,
+      retries: 3,
+    });
+  });
+
+  it('falls back to direct Langfuse config for local smoke tests', () => {
+    const cfg = readTelemetrySinkConfig({
+      LANGFUSE_PUBLIC_KEY: 'pk',
+      LANGFUSE_SECRET_KEY: 'sk',
+    });
+    expect(cfg).toMatchObject({
+      kind: 'langfuse',
+      baseUrl: 'https://us.cloud.langfuse.com',
+    });
+  });
+});
+
 describe('buildTracePayload', () => {
   it('emits a trace with nested agent + generation observations', () => {
     const batch = buildTracePayload(makeCtx());
@@ -490,6 +534,55 @@ describe('reportRunCompleted', () => {
     ]);
   });
 
+  it('POSTs serialized ingestion batches to the Open Design telemetry relay', async () => {
+    const relayConfig: TelemetrySinkConfig = {
+      kind: 'relay',
+      relayUrl: 'https://telemetry.open-design.ai/api/langfuse',
+      timeoutMs: 20_000,
+      retries: 0,
+    };
+    const fetchSpy = vi.fn().mockResolvedValue(
+      new Response('{}', { status: 200 }),
+    );
+    await reportRunCompleted(makeCtx(), {
+      config: relayConfig,
+      fetchImpl: fetchSpy as any,
+    });
+    expect(fetchSpy).toHaveBeenCalledTimes(1);
+    const call = fetchSpy.mock.calls[0]!;
+    const url = call[0] as string;
+    const init = call[1] as RequestInit & { headers: Record<string, string> };
+    expect(url).toBe('https://telemetry.open-design.ai/api/langfuse');
+    expect(init.method).toBe('POST');
+    expect(init.headers.Authorization).toBeUndefined();
+    expect(init.headers['Content-Type']).toBe('application/json');
+    expect(init.headers['X-Open-Design-Telemetry']).toBe('langfuse-ingestion-v1');
+    const body = JSON.parse(init.body as string);
+    expect(Array.isArray(body.batch)).toBe(true);
+  });
+
+  it('warns when the relay returns per-event errors', async () => {
+    const relayConfig: TelemetrySinkConfig = {
+      kind: 'relay',
+      relayUrl: 'https://telemetry.open-design.ai/api/langfuse',
+      timeoutMs: 20_000,
+      retries: 0,
+    };
+    const fetchSpy = vi.fn().mockResolvedValue(
+      new Response(
+        JSON.stringify({ successes: [], errors: [{ id: 'bad', status: 400 }] }),
+        { status: 207 },
+      ),
+    );
+    await reportRunCompleted(makeCtx(), {
+      config: relayConfig,
+      fetchImpl: fetchSpy as any,
+    });
+    expect(warnSpy).toHaveBeenCalledWith(
+      expect.stringContaining('Relay per-event errors (1)'),
+    );
+  });
+
   it('warns and drops when serialized batch exceeds the hard cap', async () => {
     // Per-field truncation already caps prompt/output, so we overflow the
     // hard cap by stuffing 50 artifact entries with very long slugs while
diff --git a/apps/packaged/src/config.ts b/apps/packaged/src/config.ts
index f655c9809..13c4e9709 100644
--- a/apps/packaged/src/config.ts
+++ b/apps/packaged/src/config.ts
@@ -21,6 +21,9 @@ export type RawPackagedConfig = {
   namespaceBaseRoot?: string;
   nodeCommandRelative?: string;
   resourceRoot?: string;
+  // Baked by tools/pack from OPEN_DESIGN_TELEMETRY_RELAY_URL and forwarded to
+  // the daemon at runtime; Langfuse credentials never ship in packaged config.
+  telemetryRelayUrl?: string;
   webSidecarEntryRelative?: string;
   webStandaloneRoot?: string;
   webOutputMode?: string;
@@ -34,6 +37,7 @@ export type PackagedConfig = {
   namespaceBaseRoot: string;
   nodeCommand: string | null;
   resourceRoot: string;
+  telemetryRelayUrl: string | null;
   webSidecarEntry: string | null;
   webStandaloneRoot: string | null;
   webOutputMode: PackagedWebOutputMode;
@@ -152,6 +156,7 @@ export async function readPackagedConfig(): Promise<PackagedConfig> {
     namespaceBaseRoot,
     nodeCommand,
     resourceRoot,
+    telemetryRelayUrl: cleanOptionalString(raw.telemetryRelayUrl),
     webSidecarEntry,
     webStandaloneRoot,
     webOutputMode,
diff --git a/apps/packaged/src/headless.ts b/apps/packaged/src/headless.ts
index b51a219d8..30aad1cf6 100644
--- a/apps/packaged/src/headless.ts
+++ b/apps/packaged/src/headless.ts
@@ -60,6 +60,7 @@ function resolveHeadlessConfig(): PackagedConfig {
     namespaceBaseRoot,
     nodeCommand: null,
     resourceRoot,
+    telemetryRelayUrl: process.env.OPEN_DESIGN_TELEMETRY_RELAY_URL?.trim() || null,
     webSidecarEntry: null,
     webStandaloneRoot: null,
     webOutputMode: "server",
@@ -107,6 +108,7 @@ async function main(): Promise<void> {
     daemonCliEntry: config.daemonCliEntry,
     daemonSidecarEntry: config.daemonSidecarEntry,
     nodeCommand: config.nodeCommand,
+    telemetryRelayUrl: config.telemetryRelayUrl,
     // PR #974 round-5 (lefarcen P2): headless packaged mode runs daemon
     // + web only, no Electron, no privileged shell.openPath surface.
     // Pinning OD_REQUIRE_DESKTOP_AUTH here would arm a gate no client
diff --git a/apps/packaged/src/index.ts b/apps/packaged/src/index.ts
index fdfe57f32..9472c4ff4 100644
--- a/apps/packaged/src/index.ts
+++ b/apps/packaged/src/index.ts
@@ -84,6 +84,7 @@ async function main(): Promise<void> {
     daemonCliEntry: config.daemonCliEntry,
     daemonSidecarEntry: config.daemonSidecarEntry,
     nodeCommand: config.nodeCommand,
+    telemetryRelayUrl: config.telemetryRelayUrl,
     // PR #974 round-5 (lefarcen P2): the Electron entry runs desktop
     // main alongside the daemon, so the import-folder gate must be
     // pinned ON from request 0. See `apps/packaged/src/headless.ts` for
diff --git a/apps/packaged/src/sidecars.ts b/apps/packaged/src/sidecars.ts
index 40638ad63..393c0e0ff 100644
--- a/apps/packaged/src/sidecars.ts
+++ b/apps/packaged/src/sidecars.ts
@@ -218,6 +218,7 @@ export type PackagedDaemonSpawnEnvOptions = {
    */
   requireDesktopAuth: boolean;
   legacyDataDir?: string | null;
+  telemetryRelayUrl?: string | null;
 };
 
 /**
@@ -247,6 +248,9 @@ export function buildPackagedDaemonSpawnEnv(
     // Electron userData, bundle names, or ports.
     ...createPackagedDaemonManagedPathEnv(paths),
     ...(options.appVersion == null ? {} : { OD_APP_VERSION: options.appVersion }),
+    ...(options.telemetryRelayUrl == null || options.telemetryRelayUrl.length === 0
+      ? {}
+      : { OPEN_DESIGN_TELEMETRY_RELAY_URL: options.telemetryRelayUrl }),
     // OD_LEGACY_DATA_DIR is the one-shot recovery handle for users
     // upgrading from 0.3.x .od/ layouts. The daemon's startup
     // migrator (legacy-data-migrator.ts) reads it; the env-allowlist
@@ -334,6 +338,7 @@ export async function startPackagedSidecars(
     daemonCliEntry: string | null;
     daemonSidecarEntry: string | null;
     nodeCommand: string | null;
+    telemetryRelayUrl: string | null;
     /**
      * PR #974 round-5 (lefarcen P2): caller asserts whether a desktop
      * runtime is being started in this packaged process group. The
@@ -369,6 +374,7 @@ export async function startPackagedSidecars(
         daemonCliEntry: options.daemonCliEntry,
         legacyDataDir: process.env.OD_LEGACY_DATA_DIR ?? null,
         requireDesktopAuth: options.requireDesktopAuth,
+        telemetryRelayUrl: options.telemetryRelayUrl,
       }),
       nodeCommand: options.nodeCommand,
       paths,
diff --git a/apps/packaged/tests/sidecars.test.ts b/apps/packaged/tests/sidecars.test.ts
index 80a1c845c..6956f6d42 100644
--- a/apps/packaged/tests/sidecars.test.ts
+++ b/apps/packaged/tests/sidecars.test.ts
@@ -208,6 +208,19 @@ describe('buildPackagedDaemonSpawnEnv', () => {
     });
     expect(env.OD_DAEMON_CLI_PATH).toBe('/path/to/cli/dist/index.js');
   });
+
+  it('forwards the packaged telemetry relay URL to the daemon when configured', () => {
+    const env = buildPackagedDaemonSpawnEnv(fakePaths(), {
+      appVersion: null,
+      daemonCliEntry: null,
+      legacyDataDir: null,
+      requireDesktopAuth: true,
+      telemetryRelayUrl: 'https://telemetry.open-design.ai/api/langfuse',
+    });
+    expect(env.OPEN_DESIGN_TELEMETRY_RELAY_URL).toBe(
+      'https://telemetry.open-design.ai/api/langfuse',
+    );
+  });
 });
 
 describe('waitForStatus child-exit fast-fail', () => {
diff --git a/apps/telemetry-worker/README.md b/apps/telemetry-worker/README.md
new file mode 100644
index 000000000..959ac06ce
--- /dev/null
+++ b/apps/telemetry-worker/README.md
@@ -0,0 +1,56 @@
+# Open Design Telemetry Relay
+
+Cloudflare Worker relay for opt-in Open Design telemetry. The shipped desktop
+client sends redacted Langfuse ingestion batches here after the user enables
+metrics. This Worker holds the Langfuse write credentials and forwards valid
+batches to Langfuse.
+
+The relay keeps Langfuse secret keys out of packaged clients. Release builds
+only include the public relay URL; the Worker adds Langfuse authentication
+server-side after validating the request. If the relay is unavailable, the
+daemon retries, logs the failure, and continues the user flow without blocking
+the CLI or desktop app.
+
+Local development can bypass the relay by setting direct `LANGFUSE_PUBLIC_KEY`
+and `LANGFUSE_SECRET_KEY` environment variables for the daemon. Packaged
+release config should use only `OPEN_DESIGN_TELEMETRY_RELAY_URL`.
+
+## Abuse controls
+
+The Worker requires the Open Design telemetry marker header, validates the
+Langfuse ingestion batch shape and size before forwarding, and uses Cloudflare
+Rate Limiting bindings for two independent keys:
+
+- `TELEMETRY_CLIENT_RATE_LIMITER`: anonymous installation/user id, 120 requests
+  per minute.
+- `TELEMETRY_IP_RATE_LIMITER`: Cloudflare `CF-Connecting-IP`, 600 requests per
+  minute.
+
+## Secrets
+
+```bash
+pnpm --dir apps/telemetry-worker dlx wrangler secret put LANGFUSE_PUBLIC_KEY
+pnpm --dir apps/telemetry-worker dlx wrangler secret put LANGFUSE_SECRET_KEY
+```
+
+`LANGFUSE_BASE_URL` defaults to `https://us.cloud.langfuse.com` in
+`wrangler.toml`.
+
+## Deploy
+
+```bash
+pnpm --filter @open-design/telemetry-worker deploy
+```
+
+After deploy, set the repository variable `OPEN_DESIGN_TELEMETRY_RELAY_URL` to
+the Worker route, for example:
+
+```text
+https://telemetry.open-design.ai/api/langfuse
+```
+
+Opening `/api/langfuse` or `/health` in a browser returns relay health JSON.
+Telemetry ingestion still uses POST to `/api/langfuse`.
+
+Release workflows bake only this public relay URL into packaged config. The
+Langfuse secret key stays in Cloudflare Worker secrets.
diff --git a/apps/telemetry-worker/package.json b/apps/telemetry-worker/package.json
new file mode 100644
index 000000000..d64c9d78b
--- /dev/null
+++ b/apps/telemetry-worker/package.json
@@ -0,0 +1,19 @@
+{
+  "name": "@open-design/telemetry-worker",
+  "version": "0.0.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "deploy": "pnpm dlx wrangler deploy",
+    "dev": "pnpm dlx wrangler dev",
+    "test": "vitest run -c vitest.config.ts",
+    "typecheck": "tsc -p tsconfig.json --noEmit"
+  },
+  "devDependencies": {
+    "typescript": "^5.6.3",
+    "vitest": "^2.1.8"
+  },
+  "engines": {
+    "node": "~24"
+  }
+}
diff --git a/apps/telemetry-worker/src/index.ts b/apps/telemetry-worker/src/index.ts
new file mode 100644
index 000000000..9b489cbae
--- /dev/null
+++ b/apps/telemetry-worker/src/index.ts
@@ -0,0 +1,201 @@
+const DEFAULT_LANGFUSE_BASE_URL = 'https://us.cloud.langfuse.com';
+const MAX_BODY_BYTES = 1024 * 1024;
+const MAX_BATCH_EVENTS = 100;
+const RELAY_MARKER_HEADER = 'X-Open-Design-Telemetry';
+const RELAY_MARKER_VALUE = 'langfuse-ingestion-v1';
+const ALLOWED_EVENT_TYPES = new Set([
+  'trace-create',
+  'span-create',
+  'generation-create',
+  'event-create',
+  'score-create',
+]);
+
+interface RateLimitBinding {
+  limit(options: { key: string }): Promise<{ success: boolean }>;
+}
+
+export interface Env {
+  LANGFUSE_PUBLIC_KEY?: string;
+  LANGFUSE_SECRET_KEY?: string;
+  LANGFUSE_BASE_URL?: string;
+  TELEMETRY_CLIENT_RATE_LIMITER?: RateLimitBinding;
+  TELEMETRY_IP_RATE_LIMITER?: RateLimitBinding;
+}
+
+function jsonResponse(status: number, body: Record<string, unknown>): Response {
+  return new Response(JSON.stringify(body), {
+    status,
+    headers: {
+      'Cache-Control': 'no-store',
+      'Content-Type': 'application/json',
+    },
+  });
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return value !== null && typeof value === 'object' && !Array.isArray(value);
+}
+
+function bodySizeBytes(value: string): number {
+  return new TextEncoder().encode(value).byteLength;
+}
+
+function basicAuthHeader(publicKey: string, secretKey: string): string {
+  const bytes = new TextEncoder().encode(`${publicKey}:${secretKey}`);
+  let binary = '';
+  for (const byte of bytes) binary += String.fromCharCode(byte);
+  return `Basic ${btoa(binary)}`;
+}
+
+function validateIngestionBody(value: unknown): string | null {
+  if (!isRecord(value)) return 'body must be a JSON object';
+  const batch = value.batch;
+  if (!Array.isArray(batch)) return 'body.batch must be an array';
+  if (batch.length === 0) return 'body.batch must not be empty';
+  if (batch.length > MAX_BATCH_EVENTS) return 'body.batch has too many events';
+
+  for (const [index, event] of batch.entries()) {
+    if (!isRecord(event)) return `body.batch[${index}] must be an object`;
+    if (typeof event.id !== 'string' || event.id.length === 0) {
+      return `body.batch[${index}].id must be a string`;
+    }
+    if (event.id.length > 200) return `body.batch[${index}].id is too long`;
+    if (typeof event.type !== 'string' || !ALLOWED_EVENT_TYPES.has(event.type)) {
+      return `body.batch[${index}].type is not allowed`;
+    }
+    if (!isRecord(event.body)) return `body.batch[${index}].body must be an object`;
+  }
+  return null;
+}
+
+function findTraceUserId(value: unknown): string | null {
+  if (!isRecord(value) || !Array.isArray(value.batch)) return null;
+  for (const event of value.batch) {
+    if (!isRecord(event) || event.type !== 'trace-create' || !isRecord(event.body)) {
+      continue;
+    }
+    const userId = event.body.userId;
+    return typeof userId === 'string' && userId.length > 0 ? userId.slice(0, 200) : null;
+  }
+  return null;
+}
+
+async function enforceRateLimits(
+  request: Request,
+  env: Env,
+  parsedBody: unknown,
+): Promise<Response | null> {
+  const clientKey = findTraceUserId(parsedBody);
+  if (clientKey && env.TELEMETRY_CLIENT_RATE_LIMITER) {
+    const { success } = await env.TELEMETRY_CLIENT_RATE_LIMITER.limit({
+      key: `client:${clientKey}`,
+    });
+    if (!success) return jsonResponse(429, { error: 'rate limit exceeded' });
+  }
+
+  const ip = request.headers.get('CF-Connecting-IP')?.trim();
+  if (ip && env.TELEMETRY_IP_RATE_LIMITER) {
+    const { success } = await env.TELEMETRY_IP_RATE_LIMITER.limit({
+      key: `ip:${ip}`,
+    });
+    if (!success) return jsonResponse(429, { error: 'rate limit exceeded' });
+  }
+
+  return null;
+}
+
+async function readBoundedBody(request: Request): Promise<string | Response> {
+  const contentLength = request.headers.get('content-length');
+  if (contentLength != null && Number(contentLength) > MAX_BODY_BYTES) {
+    return jsonResponse(413, { error: 'payload too large' });
+  }
+
+  const text = await request.text();
+  if (bodySizeBytes(text) > MAX_BODY_BYTES) {
+    return jsonResponse(413, { error: 'payload too large' });
+  }
+  return text;
+}
+
+function resolveLangfuseUrl(env: Env): string {
+  return `${(env.LANGFUSE_BASE_URL?.trim() || DEFAULT_LANGFUSE_BASE_URL).replace(/\/+$/, '')}/api/public/ingestion`;
+}
+
+function hasLangfuseCredentials(env: Env): boolean {
+  return Boolean(env.LANGFUSE_PUBLIC_KEY?.trim() && env.LANGFUSE_SECRET_KEY?.trim());
+}
+
+function isHealthPath(request: Request): boolean {
+  const { pathname } = new URL(request.url);
+  return pathname === '/api/langfuse' || pathname === '/health';
+}
+
+async function handleRequest(request: Request, env: Env): Promise<Response> {
+  if (request.method === 'GET' && isHealthPath(request)) {
+    return jsonResponse(200, {
+      ok: true,
+      service: 'open-design-telemetry-relay',
+      configured: hasLangfuseCredentials(env),
+      upstream: resolveLangfuseUrl(env),
+    });
+  }
+
+  if (request.method !== 'POST') {
+    return jsonResponse(405, { error: 'method not allowed' });
+  }
+
+  if (request.headers.get(RELAY_MARKER_HEADER) !== RELAY_MARKER_VALUE) {
+    return jsonResponse(403, { error: 'missing telemetry client marker' });
+  }
+
+  const publicKey = env.LANGFUSE_PUBLIC_KEY?.trim();
+  const secretKey = env.LANGFUSE_SECRET_KEY?.trim();
+  if (!publicKey || !secretKey) {
+    return jsonResponse(503, { error: 'telemetry relay is not configured' });
+  }
+
+  const contentType = request.headers.get('content-type') ?? '';
+  if (!contentType.toLowerCase().includes('application/json')) {
+    return jsonResponse(415, { error: 'content-type must be application/json' });
+  }
+
+  const rawBody = await readBoundedBody(request);
+  if (rawBody instanceof Response) return rawBody;
+
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(rawBody);
+  } catch {
+    return jsonResponse(400, { error: 'invalid JSON' });
+  }
+
+  const validationError = validateIngestionBody(parsed);
+  if (validationError != null) {
+    return jsonResponse(400, { error: validationError });
+  }
+
+  const rateLimitResponse = await enforceRateLimits(request, env, parsed);
+  if (rateLimitResponse) return rateLimitResponse;
+
+  const upstream = await fetch(resolveLangfuseUrl(env), {
+    method: 'POST',
+    headers: {
+      Authorization: basicAuthHeader(publicKey, secretKey),
+      'Content-Type': 'application/json',
+    },
+    body: rawBody,
+  });
+  const upstreamBody = await upstream.text();
+  return new Response(upstreamBody, {
+    status: upstream.status,
+    headers: {
+      'Cache-Control': 'no-store',
+      'Content-Type': upstream.headers.get('content-type') ?? 'application/json',
+    },
+  });
+}
+
+export default {
+  fetch: handleRequest,
+};
diff --git a/apps/telemetry-worker/tests/index.test.ts b/apps/telemetry-worker/tests/index.test.ts
new file mode 100644
index 000000000..9aa37fe3a
--- /dev/null
+++ b/apps/telemetry-worker/tests/index.test.ts
@@ -0,0 +1,148 @@
+import { describe, expect, it, vi } from 'vitest';
+
+import worker, { type Env } from '../src/index';
+
+const env: Env = {
+  LANGFUSE_PUBLIC_KEY: 'pk-lf-test',
+  LANGFUSE_SECRET_KEY: 'sk-lf-test',
+  LANGFUSE_BASE_URL: 'https://us.cloud.langfuse.com',
+};
+
+function makeRequest(body: unknown): Request {
+  return new Request('https://telemetry.open-design.ai/api/langfuse', {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+      'X-Open-Design-Telemetry': 'langfuse-ingestion-v1',
+    },
+    body: JSON.stringify(body),
+  });
+}
+
+function makeRateLimiter(success: boolean) {
+  return {
+    limit: vi.fn(async () => ({ success })),
+  };
+}
+
+describe('telemetry worker', () => {
+  it('returns a health response for browser checks', async () => {
+    const response = await worker.fetch(
+      new Request('https://telemetry.open-design.ai/api/langfuse'),
+      env,
+    );
+
+    expect(response.status).toBe(200);
+    expect(await response.json()).toEqual({
+      ok: true,
+      service: 'open-design-telemetry-relay',
+      configured: true,
+      upstream: 'https://us.cloud.langfuse.com/api/public/ingestion',
+    });
+  });
+
+  it('reports unconfigured health without exposing secrets', async () => {
+    const response = await worker.fetch(new Request('https://telemetry.open-design.ai/health'), {});
+
+    expect(response.status).toBe(200);
+    expect(await response.json()).toEqual({
+      ok: true,
+      service: 'open-design-telemetry-relay',
+      configured: false,
+      upstream: 'https://us.cloud.langfuse.com/api/public/ingestion',
+    });
+  });
+
+  it('forwards valid Langfuse ingestion batches with server-side auth', async () => {
+    const fetchSpy = vi.spyOn(globalThis, 'fetch').mockResolvedValue(
+      new Response(JSON.stringify({ successes: [{ id: 'evt-1' }], errors: [] }), {
+        status: 207,
+        headers: { 'Content-Type': 'application/json' },
+      }),
+    );
+
+    const response = await worker.fetch(
+      makeRequest({
+        batch: [
+          {
+            id: 'evt-1',
+            type: 'trace-create',
+            timestamp: '2026-05-11T00:00:00.000Z',
+            body: { id: 'trace-1', name: 'open-design-turn' },
+          },
+        ],
+      }),
+      env,
+    );
+
+    expect(response.status).toBe(207);
+    expect(fetchSpy).toHaveBeenCalledTimes(1);
+    const [url, init] = fetchSpy.mock.calls[0]!;
+    expect(url).toBe('https://us.cloud.langfuse.com/api/public/ingestion');
+    expect((init as RequestInit).headers).toMatchObject({
+      Authorization: expect.stringMatching(/^Basic /),
+      'Content-Type': 'application/json',
+    });
+
+    fetchSpy.mockRestore();
+  });
+
+  it('rejects requests without the Open Design client marker', async () => {
+    const response = await worker.fetch(
+      new Request('https://telemetry.open-design.ai/api/langfuse', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ batch: [] }),
+      }),
+      env,
+    );
+
+    expect(response.status).toBe(403);
+  });
+
+  it('rate limits validated batches before forwarding', async () => {
+    const fetchSpy = vi.spyOn(globalThis, 'fetch');
+    const limiter = makeRateLimiter(false);
+    const response = await worker.fetch(
+      makeRequest({
+        batch: [
+          {
+            id: 'evt-1',
+            type: 'trace-create',
+            timestamp: '2026-05-11T00:00:00.000Z',
+            body: {
+              id: 'trace-1',
+              name: 'open-design-turn',
+              userId: 'installation-1',
+            },
+          },
+        ],
+      }),
+      { ...env, TELEMETRY_CLIENT_RATE_LIMITER: limiter },
+    );
+
+    expect(response.status).toBe(429);
+    expect(limiter.limit).toHaveBeenCalledWith({ key: 'client:installation-1' });
+    expect(fetchSpy).not.toHaveBeenCalled();
+
+    fetchSpy.mockRestore();
+  });
+
+  it('rejects malformed batches before forwarding', async () => {
+    const fetchSpy = vi.spyOn(globalThis, 'fetch');
+    const response = await worker.fetch(makeRequest({ batch: [{ type: 'bad' }] }), env);
+
+    expect(response.status).toBe(400);
+    expect(await response.json()).toEqual({
+      error: 'body.batch[0].id must be a string',
+    });
+    expect(fetchSpy).not.toHaveBeenCalled();
+
+    fetchSpy.mockRestore();
+  });
+
+  it('fails closed when Langfuse credentials are absent', async () => {
+    const response = await worker.fetch(makeRequest({ batch: [] }), {});
+    expect(response.status).toBe(503);
+  });
+});
diff --git a/apps/telemetry-worker/tsconfig.json b/apps/telemetry-worker/tsconfig.json
new file mode 100644
index 000000000..0d7dfbbd7
--- /dev/null
+++ b/apps/telemetry-worker/tsconfig.json
@@ -0,0 +1,19 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "lib": ["ES2022", "WebWorker"],
+    "module": "ESNext",
+    "moduleResolution": "Bundler",
+    "strict": true,
+    "noUncheckedIndexedAccess": true,
+    "exactOptionalPropertyTypes": true,
+    "allowJs": false,
+    "checkJs": false,
+    "isolatedModules": true,
+    "forceConsistentCasingInFileNames": true,
+    "skipLibCheck": true,
+    "types": ["vitest/globals"]
+  },
+  "include": ["src/**/*.ts", "tests/**/*.ts", "vitest.config.ts"],
+  "exclude": ["node_modules", "dist"]
+}
diff --git a/apps/telemetry-worker/vitest.config.ts b/apps/telemetry-worker/vitest.config.ts
new file mode 100644
index 000000000..4ac6027d5
--- /dev/null
+++ b/apps/telemetry-worker/vitest.config.ts
@@ -0,0 +1,7 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    environment: 'node',
+  },
+});
diff --git a/apps/telemetry-worker/wrangler.toml b/apps/telemetry-worker/wrangler.toml
new file mode 100644
index 000000000..3516ccd16
--- /dev/null
+++ b/apps/telemetry-worker/wrangler.toml
@@ -0,0 +1,25 @@
+name = "open-design-telemetry-relay"
+account_id = "64ad4569ffd912432d6b86d5656484c4"
+main = "src/index.ts"
+compatibility_date = "2026-05-01"
+workers_dev = false
+routes = [
+  { pattern = "telemetry.open-design.ai", custom_domain = true }
+]
+
+[vars]
+LANGFUSE_BASE_URL = "https://us.cloud.langfuse.com"
+
+[[ratelimits]]
+name = "TELEMETRY_CLIENT_RATE_LIMITER"
+namespace_id = "1001"
+  [ratelimits.simple]
+  limit = 120
+  period = 60
+
+[[ratelimits]]
+name = "TELEMETRY_IP_RATE_LIMITER"
+namespace_id = "1002"
+  [ratelimits.simple]
+  limit = 600
+  period = 60
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 7f49054ec..b72d0ffd0 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -178,6 +178,15 @@ importers:
         specifier: ^2.1.8
         version: 2.1.9(@types/node@24.12.2)(jsdom@29.1.1)
 
+  apps/telemetry-worker:
+    devDependencies:
+      typescript:
+        specifier: ^5.6.3
+        version: 5.9.3
+      vitest:
+        specifier: ^2.1.8
+        version: 2.1.9(@types/node@24.12.2)(jsdom@29.1.1)
+
   apps/web:
     dependencies:
       '@anthropic-ai/sdk':
diff --git a/tools/pack/src/config.ts b/tools/pack/src/config.ts
index 5a207d7ad..1652dbc59 100644
--- a/tools/pack/src/config.ts
+++ b/tools/pack/src/config.ts
@@ -72,6 +72,7 @@ export type ToolPackConfig = {
   roots: ToolPackRoots;
   silent: boolean;
   signed: boolean;
+  telemetryRelayUrl?: string;
   to: ToolPackBuildOutput;
   webOutputMode: ToolPackWebOutputMode;
   workspaceRoot: string;
@@ -108,6 +109,22 @@ function resolveToolPackWebOutputMode(platform: ToolPackPlatform, value: string
   throw new Error(`unsupported OD_WEB_OUTPUT_MODE value: ${value}`);
 }
 
+function resolveToolPackTelemetryRelayUrl(value: string | undefined): string | undefined {
+  if (value == null) return undefined;
+  const normalized = value.trim();
+  if (normalized.length === 0) return undefined;
+  let parsed: URL;
+  try {
+    parsed = new URL(normalized);
+  } catch {
+    throw new Error(`OPEN_DESIGN_TELEMETRY_RELAY_URL must be an absolute https URL: ${value}`);
+  }
+  if (parsed.protocol !== "https:") {
+    throw new Error(`OPEN_DESIGN_TELEMETRY_RELAY_URL must use https: ${value}`);
+  }
+  return normalized.replace(/\/+$/, "");
+}
+
 function resolveElectronVersion(workspaceRoot: string): string {
   const require = createRequire(join(workspaceRoot, "apps/desktop/package.json"));
   const desktopPackage = require(join(workspaceRoot, "apps/desktop/package.json")) as {
@@ -177,6 +194,7 @@ export function resolveToolPackConfig(
     removeSidecars: options.removeSidecars === true,
     silent: options.silent !== false,
     signed: options.signed === true,
+    telemetryRelayUrl: resolveToolPackTelemetryRelayUrl(process.env.OPEN_DESIGN_TELEMETRY_RELAY_URL),
     to: resolveToolPackBuildOutput(platform, options.to),
     webOutputMode: resolveToolPackWebOutputMode(platform, process.env.OD_WEB_OUTPUT_MODE),
     workspaceRoot: WORKSPACE_ROOT,
diff --git a/tools/pack/src/linux.ts b/tools/pack/src/linux.ts
index f2ebfa78c..8ddef5c07 100644
--- a/tools/pack/src/linux.ts
+++ b/tools/pack/src/linux.ts
@@ -134,7 +134,7 @@ export function buildDockerArgs(
   }
   const innerCommand = `${pnpmCmd} install --frozen-lockfile && ` + innerArgs.join(" ");
 
-  return [
+  const dockerArgs = [
     "run",
     "--rm",
     "--user",
@@ -155,13 +155,19 @@ export function buildDockerArgs(
     "ELECTRON_CACHE=/home/builder/.cache/electron",
     "-e",
     "ELECTRON_BUILDER_CACHE=/home/builder/.cache/electron-builder",
+  ];
+  if (config.telemetryRelayUrl != null) {
+    dockerArgs.push("-e", `OPEN_DESIGN_TELEMETRY_RELAY_URL=${config.telemetryRelayUrl}`);
+  }
+  dockerArgs.push(
     "-w",
     "/project",
     "electronuserland/builder:base",
     "bash",
     "-lc",
     innerCommand,
-  ];
+  );
+  return dockerArgs;
 }
 
 export type DesktopTemplateValues = {
@@ -385,6 +391,7 @@ async function writeAssembledApp(
         appVersion: version,
         namespace: config.namespace,
         nodeCommandRelative: "open-design/bin/node",
+        ...(config.telemetryRelayUrl == null ? {} : { telemetryRelayUrl: config.telemetryRelayUrl }),
         ...(config.portable ? {} : { namespaceBaseRoot: config.roots.runtime.namespaceBaseRoot }),
       },
       null,
diff --git a/tools/pack/src/mac/app.ts b/tools/pack/src/mac/app.ts
index ab2b6f1de..0d1580190 100644
--- a/tools/pack/src/mac/app.ts
+++ b/tools/pack/src/mac/app.ts
@@ -233,6 +233,7 @@ export async function writeAssembledApp(
         ...(usePrebundledStandaloneWeb ? { daemonSidecarEntryRelative: MAC_PREBUNDLED_DAEMON_SIDECAR_RELATIVE_PATH } : {}),
         namespace: config.namespace,
         nodeCommandRelative: "open-design/bin/node",
+        ...(config.telemetryRelayUrl == null ? {} : { telemetryRelayUrl: config.telemetryRelayUrl }),
         ...(usePrebundledStandaloneWeb ? { webSidecarEntryRelative: MAC_PREBUNDLED_WEB_SIDECAR_RELATIVE_PATH } : {}),
         webOutputMode: config.webOutputMode,
         ...(config.portable ? {} : { namespaceBaseRoot: config.roots.runtime.namespaceBaseRoot }),
diff --git a/tools/pack/src/win/manifest.ts b/tools/pack/src/win/manifest.ts
index 77a04f402..875d05eab 100644
--- a/tools/pack/src/win/manifest.ts
+++ b/tools/pack/src/win/manifest.ts
@@ -19,6 +19,7 @@ function createPackagedConfig(config: ToolPackConfig, packagedVersion: string):
   return {
     appVersion: packagedVersion,
     namespace: config.namespace,
+    ...(config.telemetryRelayUrl == null ? {} : { telemetryRelayUrl: config.telemetryRelayUrl }),
     webOutputMode: config.webOutputMode,
     ...(config.portable ? {} : { namespaceBaseRoot: config.roots.runtime.namespaceBaseRoot }),
   };
diff --git a/tools/pack/tests/config.test.ts b/tools/pack/tests/config.test.ts
new file mode 100644
index 000000000..bce1a7903
--- /dev/null
+++ b/tools/pack/tests/config.test.ts
@@ -0,0 +1,35 @@
+import { afterEach, describe, expect, it } from "vitest";
+
+import { resolveToolPackConfig } from "../src/config.js";
+
+const savedTelemetryRelayUrl = process.env.OPEN_DESIGN_TELEMETRY_RELAY_URL;
+
+afterEach(() => {
+  if (savedTelemetryRelayUrl == null) {
+    delete process.env.OPEN_DESIGN_TELEMETRY_RELAY_URL;
+  } else {
+    process.env.OPEN_DESIGN_TELEMETRY_RELAY_URL = savedTelemetryRelayUrl;
+  }
+});
+
+describe("resolveToolPackConfig telemetry relay", () => {
+  it("reads and normalizes OPEN_DESIGN_TELEMETRY_RELAY_URL for packaged config", () => {
+    process.env.OPEN_DESIGN_TELEMETRY_RELAY_URL = "https://telemetry.open-design.ai/api/langfuse//";
+    const config = resolveToolPackConfig("mac", { namespace: "telemetry-test" });
+    expect(config.telemetryRelayUrl).toBe("https://telemetry.open-design.ai/api/langfuse");
+  });
+
+  it("rejects invalid telemetry relay URLs", () => {
+    process.env.OPEN_DESIGN_TELEMETRY_RELAY_URL = "not-a-url";
+    expect(() => resolveToolPackConfig("mac")).toThrow(
+      /OPEN_DESIGN_TELEMETRY_RELAY_URL must be an absolute https URL/,
+    );
+  });
+
+  it("rejects plaintext telemetry relay URLs for packaged config", () => {
+    process.env.OPEN_DESIGN_TELEMETRY_RELAY_URL = "http://telemetry.open-design.ai/api/langfuse";
+    expect(() => resolveToolPackConfig("mac")).toThrow(
+      /OPEN_DESIGN_TELEMETRY_RELAY_URL must use https/,
+    );
+  });
+});
diff --git a/tools/pack/tests/linux.test.ts b/tools/pack/tests/linux.test.ts
index ab19d26f0..5e2953915 100644
--- a/tools/pack/tests/linux.test.ts
+++ b/tools/pack/tests/linux.test.ts
@@ -86,6 +86,17 @@ describe("buildDockerArgs", () => {
     expect(args).toContain("ELECTRON_BUILDER_CACHE=/home/builder/.cache/electron-builder");
   });
 
+  it("passes the telemetry relay URL into containerized builds when configured", () => {
+    const args = buildDockerArgs(
+      {
+        ...makeConfig(),
+        telemetryRelayUrl: "https://telemetry.open-design.ai/api/langfuse",
+      },
+      { uid: 1000, gid: 1000 },
+    );
+    expect(args).toContain("OPEN_DESIGN_TELEMETRY_RELAY_URL=https://telemetry.open-design.ai/api/langfuse");
+  });
+
   it("re-invokes pnpm tools-pack linux build inside the container without --containerized", () => {
     const args = buildDockerArgs(makeConfig(), { uid: 1000, gid: 1000 });
     const last = args[args.length - 1];