diff --git a/cloudflare/src/bindings.ts b/cloudflare/src/bindings.ts
index 43e4416..caeb7e0 100644
--- a/cloudflare/src/bindings.ts
+++ b/cloudflare/src/bindings.ts
@@ -51,6 +51,7 @@ export interface Env {
   ELY_STORAGE: ElyR2Bucket;
   ELY_RATE_LIMITER: ElyRateLimit;
   ELY_API_AUDIT: ElyAnalyticsDataset;
+  ELY_DIAGNOSTICS: ElyAnalyticsDataset;
   ELY_ENVIRONMENT: string;
   ELY_AUTH_BASE_URL: string;
   ELY_AUTH_SECRET: string;
diff --git a/cloudflare/src/index.ts b/cloudflare/src/index.ts
index 801bb10..bdd6a34 100644
--- a/cloudflare/src/index.ts
+++ b/cloudflare/src/index.ts
@@ -33,6 +33,10 @@ import {
   publicSigningKeysKvKey,
 } from "./signing_keys.js";
 import { handleSyncRoute } from "./sync_routes.js";
+import {
+  TelemetrySchemaError,
+  telemetryEventAcceptedDocument,
+} from "./telemetry.js";
 import { jsonResponse } from "./responses.js";
 
 export default {
@@ -199,6 +203,32 @@ export async function handleRequest(request: Request, env: Env): Promise<Respons
       handleReleaseSignature(env, url),
     );
   }
+  if (url.pathname === "/api/telemetry/events") {
+    return withAuthenticatedApiControls(
+      request,
+      env,
+      "telemetry.events",
+      ["POST"],
+      async (context) => {
+        try {
+          return jsonResponse(
+            await telemetryEventAcceptedDocument(request, env, context),
+            202,
+            { "Cache-Control": "no-store" },
+          );
+        } catch (error) {
+          if (error instanceof TelemetrySchemaError) {
+            return jsonResponse(
+              { error: error.code },
+              400,
+              { "Cache-Control": "no-store" },
+            );
+          }
+          throw error;
+        }
+      },
+    );
+  }
 
   return jsonResponse({ error: "not_found" }, 404);
 }
diff --git a/cloudflare/src/telemetry.ts b/cloudflare/src/telemetry.ts
new file mode 100644
index 0000000..c8dc32a
--- /dev/null
+++ b/cloudflare/src/telemetry.ts
@@ -0,0 +1,262 @@
+import type { AuthContext } from "./auth.js";
+import type { Env } from "./bindings.js";
+
+const EVENT_TYPES = new Set([
+  "app_startup",
+  "app_crash",
+  "webview_crash",
+  "sync_error",
+  "plugin_crash",
+  "update_result",
+]);
+const OUTCOMES = new Set(["success", "failure"]);
+const PLATFORMS = new Set(["macos", "windows", "linux"]);
+const ALLOWED_FIELDS = new Set([
+  "version",
+  "event_type",
+  "occurred_at",
+  "app_version",
+  "platform",
+  "outcome",
+  "error_code",
+  "component",
+  "crash_kind",
+  "plugin_id",
+]);
+const SENSITIVE_FIELDS = new Set([
+  "url",
+  "loaded_url",
+  "loadedurl",
+  "page_url",
+  "pageurl",
+  "title",
+  "page_title",
+  "pagetitle",
+  "search_term",
+  "searchterm",
+  "query",
+  "bookmark",
+  "bookmark_content",
+  "bookmarkcontent",
+  "history",
+  "history_content",
+  "historycontent",
+  "note",
+  "notes",
+  "notes_content",
+  "notescontent",
+  "cookie",
+  "cookies",
+  "form",
+  "form_input",
+  "forminput",
+  "input",
+  "field_value",
+  "fieldvalue",
+  "payload",
+  "body",
+  "page_text",
+  "pagetext",
+]);
+const APP_VERSION_PATTERN = /^[0-9A-Za-z][0-9A-Za-z._+-]{0,63}$/;
+const CODE_PATTERN = /^[0-9A-Za-z][0-9A-Za-z._:-]{0,79}$/;
+
+type TelemetryRequestBody = Record<string, unknown>;
+type TelemetryEventType =
+  | "app_startup"
+  | "app_crash"
+  | "webview_crash"
+  | "sync_error"
+  | "plugin_crash"
+  | "update_result";
+type TelemetryOutcome = "success" | "failure";
+type TelemetryPlatform = "macos" | "windows" | "linux";
+
+export interface TelemetryAcceptedDocument {
+  version: 1;
+  accepted: true;
+}
+
+interface TelemetryEvent {
+  eventType: TelemetryEventType;
+  occurredAt: number;
+  appVersion: string;
+  platform: TelemetryPlatform;
+  outcome?: TelemetryOutcome;
+  errorCode?: string;
+  component?: string;
+  crashKind?: string;
+  pluginId?: string;
+}
+
+export class TelemetrySchemaError extends Error {
+  constructor(readonly code: string) {
+    super(code);
+    this.name = "TelemetrySchemaError";
+  }
+}
+
+export async function telemetryEventAcceptedDocument(
+  request: Request,
+  env: Env,
+  context: AuthContext,
+): Promise<TelemetryAcceptedDocument> {
+  const event = await telemetryEvent(request);
+  env.ELY_DIAGNOSTICS.writeDataPoint({
+    indexes: [env.ELY_ENVIRONMENT],
+    blobs: [
+      event.eventType,
+      event.appVersion,
+      event.platform,
+      event.outcome ?? "",
+      event.errorCode ?? "",
+      event.component ?? "",
+      event.crashKind ?? "",
+      event.pluginId ?? "",
+      context.userId,
+      context.deviceId ?? "",
+    ],
+    doubles: [event.occurredAt, Date.now()],
+  });
+  return { version: 1, accepted: true };
+}
+
+async function telemetryEvent(request: Request): Promise<TelemetryEvent> {
+  const body = await requestBody(request);
+  assertNoSensitiveFields(body);
+  assertOnlyFields(body);
+  if (body.version !== 1) {
+    throw new TelemetrySchemaError("telemetry_version_invalid");
+  }
+
+  const event: TelemetryEvent = {
+    eventType: eventType(body.event_type),
+    occurredAt: integer(body.occurred_at, "telemetry_occurred_at_invalid"),
+    appVersion: appVersion(body.app_version),
+    platform: platform(body.platform),
+  };
+  assignOptionalString(event, "outcome", outcome(body.outcome));
+  assignOptionalString(event, "errorCode", code(body.error_code, "telemetry_error_code_invalid"));
+  assignOptionalString(event, "component", code(body.component, "telemetry_component_invalid"));
+  assignOptionalString(event, "crashKind", code(body.crash_kind, "telemetry_crash_kind_invalid"));
+  assignOptionalString(event, "pluginId", code(body.plugin_id, "telemetry_plugin_id_invalid"));
+  assertRequiredEventFields(event);
+  return event;
+}
+
+async function requestBody(request: Request): Promise<TelemetryRequestBody> {
+  let value: unknown;
+  try {
+    value = await request.json();
+  } catch {
+    throw new TelemetrySchemaError("telemetry_json_invalid");
+  }
+  if (!isRecord(value)) {
+    throw new TelemetrySchemaError("telemetry_body_invalid");
+  }
+  return value;
+}
+
+function assertNoSensitiveFields(value: unknown): void {
+  if (Array.isArray(value)) {
+    for (const item of value) {
+      assertNoSensitiveFields(item);
+    }
+    return;
+  }
+  if (!isRecord(value)) {
+    return;
+  }
+  for (const [field, fieldValue] of Object.entries(value)) {
+    if (SENSITIVE_FIELDS.has(field.toLowerCase())) {
+      throw new TelemetrySchemaError("telemetry_sensitive_field");
+    }
+    assertNoSensitiveFields(fieldValue);
+  }
+}
+
+function assertOnlyFields(value: TelemetryRequestBody): void {
+  for (const field of Object.keys(value)) {
+    if (!ALLOWED_FIELDS.has(field)) {
+      throw new TelemetrySchemaError("telemetry_unknown_field");
+    }
+  }
+}
+
+function eventType(value: unknown): TelemetryEventType {
+  if (typeof value !== "string" || !EVENT_TYPES.has(value)) {
+    throw new TelemetrySchemaError("telemetry_event_type_invalid");
+  }
+  return value as TelemetryEventType;
+}
+
+function platform(value: unknown): TelemetryPlatform {
+  if (typeof value !== "string" || !PLATFORMS.has(value)) {
+    throw new TelemetrySchemaError("telemetry_platform_invalid");
+  }
+  return value as TelemetryPlatform;
+}
+
+function outcome(value: unknown): TelemetryOutcome | undefined {
+  if (value === undefined) {
+    return undefined;
+  }
+  if (typeof value !== "string" || !OUTCOMES.has(value)) {
+    throw new TelemetrySchemaError("telemetry_outcome_invalid");
+  }
+  return value as TelemetryOutcome;
+}
+
+function appVersion(value: unknown): string {
+  if (typeof value !== "string" || !APP_VERSION_PATTERN.test(value)) {
+    throw new TelemetrySchemaError("telemetry_app_version_invalid");
+  }
+  return value;
+}
+
+function code(value: unknown, errorCode: string): string | undefined {
+  if (value === undefined) {
+    return undefined;
+  }
+  if (typeof value !== "string" || !CODE_PATTERN.test(value)) {
+    throw new TelemetrySchemaError(errorCode);
+  }
+  return value;
+}
+
+function integer(value: unknown, errorCode: string): number {
+  if (typeof value !== "number" || !Number.isSafeInteger(value) || value < 0) {
+    throw new TelemetrySchemaError(errorCode);
+  }
+  return value;
+}
+
+function assignOptionalString<T extends object, K extends keyof T>(
+  target: T,
+  field: K,
+  value: T[K] | undefined,
+): void {
+  if (value !== undefined) {
+    target[field] = value;
+  }
+}
+
+function assertRequiredEventFields(event: TelemetryEvent): void {
+  if ((event.eventType === "app_startup" || event.eventType === "update_result")
+    && event.outcome === undefined) {
+    throw new TelemetrySchemaError("telemetry_outcome_required");
+  }
+  if (event.eventType === "sync_error" && event.errorCode === undefined) {
+    throw new TelemetrySchemaError("telemetry_error_code_required");
+  }
+  if (event.eventType === "webview_crash" && event.crashKind === undefined) {
+    throw new TelemetrySchemaError("telemetry_crash_kind_required");
+  }
+  if (event.eventType === "plugin_crash" && event.pluginId === undefined) {
+    throw new TelemetrySchemaError("telemetry_plugin_id_required");
+  }
+}
+
+function isRecord(value: unknown): value is TelemetryRequestBody {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
diff --git a/cloudflare/tests/api_controls.test.ts b/cloudflare/tests/api_controls.test.ts
index 16c9a36..649dc88 100644
--- a/cloudflare/tests/api_controls.test.ts
+++ b/cloudflare/tests/api_controls.test.ts
@@ -334,6 +334,9 @@ function testEnv(options: TestEnvOptions = {}): Env {
         }
       },
     },
+    ELY_DIAGNOSTICS: {
+      writeDataPoint(): void {},
+    },
   };
 }
 
diff --git a/cloudflare/tests/devices_test_support.ts b/cloudflare/tests/devices_test_support.ts
index 1453553..6e55226 100644
--- a/cloudflare/tests/devices_test_support.ts
+++ b/cloudflare/tests/devices_test_support.ts
@@ -11,6 +11,7 @@ export const PUBLIC_KEY = "a".repeat(64);
 
 export interface TestEnvOptions {
   auditEvents?: ElyAnalyticsDataPoint[];
+  diagnosticEvents?: ElyAnalyticsDataPoint[];
   d1?: RecordedD1Database;
   kvEntries?: [string, string][];
   kvReads?: string[];
@@ -68,6 +69,13 @@ export function testEnv(options: TestEnvOptions): Env {
         }
       },
     },
+    ELY_DIAGNOSTICS: {
+      writeDataPoint(event?: ElyAnalyticsDataPoint): void {
+        if (event !== undefined) {
+          options.diagnosticEvents?.push(event);
+        }
+      },
+    },
   };
 }
 
diff --git a/cloudflare/tests/index.test.ts b/cloudflare/tests/index.test.ts
index 3f367b0..349d585 100644
--- a/cloudflare/tests/index.test.ts
+++ b/cloudflare/tests/index.test.ts
@@ -369,6 +369,9 @@ function testEnv(
     ELY_API_AUDIT: {
       writeDataPoint(): void {},
     },
+    ELY_DIAGNOSTICS: {
+      writeDataPoint(): void {},
+    },
   };
 }
 
diff --git a/cloudflare/tests/telemetry_routes.test.ts b/cloudflare/tests/telemetry_routes.test.ts
new file mode 100644
index 0000000..abe521c
--- /dev/null
+++ b/cloudflare/tests/telemetry_routes.test.ts
@@ -0,0 +1,175 @@
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+
+import type { ElyAnalyticsDataPoint } from "../src/bindings.js";
+import { authSessionCacheKvKey, authTokenHash } from "../src/auth.js";
+import { handleRequest } from "../src/index.js";
+import { ACCESS_TOKEN, sessionDocument, testEnv } from "./devices_test_support.js";
+
+const DEVICE_ID = "device-01";
+
+describe("telemetry routes", () => {
+  it("records a minimized authenticated diagnostic event", async () => {
+    const tokenHash = await authTokenHash(ACCESS_TOKEN);
+    const auditEvents: ElyAnalyticsDataPoint[] = [];
+    const diagnosticEvents: ElyAnalyticsDataPoint[] = [];
+    const response = await handleRequest(
+      telemetryRequest({
+        version: 1,
+        event_type: "sync_error",
+        occurred_at: 1_780_000_000,
+        app_version: "0.1.0",
+        platform: "macos",
+        error_code: "sync.pull.5xx",
+        component: "sync",
+      }),
+      testEnv({
+        auditEvents,
+        diagnosticEvents,
+        kvEntries: [[authSessionCacheKvKey("local", tokenHash), sessionDocument(DEVICE_ID)]],
+      }),
+    );
+
+    assert.equal(response.status, 202);
+    assert.equal(response.headers.get("cache-control"), "no-store");
+    assert.deepEqual(await response.json(), { version: 1, accepted: true });
+    assert.equal(diagnosticEvents.length, 1);
+    assert.deepEqual(diagnosticEvents[0]?.indexes, ["local"]);
+    assert.deepEqual(diagnosticEvents[0]?.blobs, [
+      "sync_error",
+      "0.1.0",
+      "macos",
+      "",
+      "sync.pull.5xx",
+      "sync",
+      "",
+      "",
+      "user-01",
+      DEVICE_ID,
+    ]);
+    assert.equal(diagnosticEvents[0]?.doubles?.[0], 1_780_000_000);
+    assert.ok((diagnosticEvents[0]?.doubles?.[1] ?? 0) > 0);
+    assert.deepEqual(auditEvents[0]?.blobs?.slice(0, 4), [
+      "telemetry.events",
+      "POST",
+      "/api/telemetry/events",
+      "handled",
+    ]);
+  });
+
+  it("rejects diagnostic events containing sensitive fields", async () => {
+    const tokenHash = await authTokenHash(ACCESS_TOKEN);
+    const diagnosticEvents: ElyAnalyticsDataPoint[] = [];
+    const response = await handleRequest(
+      telemetryRequest({
+        version: 1,
+        event_type: "app_startup",
+        occurred_at: 1_780_000_000,
+        app_version: "0.1.0",
+        platform: "macos",
+        outcome: "success",
+        url: "https://example.test/private?q=token",
+      }),
+      testEnv({
+        diagnosticEvents,
+        kvEntries: [[authSessionCacheKvKey("local", tokenHash), sessionDocument(DEVICE_ID)]],
+      }),
+    );
+
+    assert.equal(response.status, 400);
+    assert.deepEqual(await response.json(), { error: "telemetry_sensitive_field" });
+    assert.equal(diagnosticEvents.length, 0);
+  });
+
+  it("rejects unknown diagnostic fields", async () => {
+    const tokenHash = await authTokenHash(ACCESS_TOKEN);
+    const diagnosticEvents: ElyAnalyticsDataPoint[] = [];
+    const response = await handleRequest(
+      telemetryRequest({
+        version: 1,
+        event_type: "update_result",
+        occurred_at: 1_780_000_000,
+        app_version: "0.1.0",
+        platform: "macos",
+        outcome: "failure",
+        metadata: { release_channel: "stable" },
+      }),
+      testEnv({
+        diagnosticEvents,
+        kvEntries: [[authSessionCacheKvKey("local", tokenHash), sessionDocument(DEVICE_ID)]],
+      }),
+    );
+
+    assert.equal(response.status, 400);
+    assert.deepEqual(await response.json(), { error: "telemetry_unknown_field" });
+    assert.equal(diagnosticEvents.length, 0);
+  });
+
+  it("rejects unsupported diagnostic event types", async () => {
+    const tokenHash = await authTokenHash(ACCESS_TOKEN);
+    const diagnosticEvents: ElyAnalyticsDataPoint[] = [];
+    const response = await handleRequest(
+      telemetryRequest({
+        version: 1,
+        event_type: "page_view",
+        occurred_at: 1_780_000_000,
+        app_version: "0.1.0",
+        platform: "macos",
+      }),
+      testEnv({
+        diagnosticEvents,
+        kvEntries: [[authSessionCacheKvKey("local", tokenHash), sessionDocument(DEVICE_ID)]],
+      }),
+    );
+
+    assert.equal(response.status, 400);
+    assert.deepEqual(await response.json(), { error: "telemetry_event_type_invalid" });
+    assert.equal(diagnosticEvents.length, 0);
+  });
+
+  it("rejects unauthenticated diagnostic events before recording telemetry", async () => {
+    const diagnosticEvents: ElyAnalyticsDataPoint[] = [];
+    const response = await handleRequest(
+      new Request("https://elydora.test/api/telemetry/events", {
+        method: "POST",
+        headers: { "content-type": "application/json" },
+        body: JSON.stringify({
+          version: 1,
+          event_type: "app_crash",
+          occurred_at: 1_780_000_000,
+          app_version: "0.1.0",
+          platform: "macos",
+        }),
+      }),
+      testEnv({ diagnosticEvents }),
+    );
+
+    assert.equal(response.status, 401);
+    assert.deepEqual(await response.json(), { error: "authorization_missing" });
+    assert.equal(diagnosticEvents.length, 0);
+  });
+
+  it("rejects unsupported methods before recording telemetry", async () => {
+    const diagnosticEvents: ElyAnalyticsDataPoint[] = [];
+    const response = await handleRequest(
+      new Request("https://elydora.test/api/telemetry/events", { method: "GET" }),
+      testEnv({ diagnosticEvents }),
+    );
+
+    assert.equal(response.status, 405);
+    assert.equal(response.headers.get("allow"), "POST");
+    assert.deepEqual(await response.json(), { error: "method_not_allowed" });
+    assert.equal(diagnosticEvents.length, 0);
+  });
+});
+
+function telemetryRequest(body: Record<string, unknown>): Request {
+  return new Request("https://elydora.test/api/telemetry/events", {
+    method: "POST",
+    headers: {
+      authorization: `Bearer ${ACCESS_TOKEN}`,
+      "content-type": "application/json",
+    },
+    body: JSON.stringify(body),
+  });
+}
diff --git a/cloudflare/wrangler.toml b/cloudflare/wrangler.toml
index 9363ae6..6a2d6be 100644
--- a/cloudflare/wrangler.toml
+++ b/cloudflare/wrangler.toml
@@ -25,6 +25,10 @@ ELY_AUTH_BASE_URL = "http://localhost:8787"
 binding = "ELY_API_AUDIT"
 dataset = "ely_api_audit"
 
+[[analytics_engine_datasets]]
+binding = "ELY_DIAGNOSTICS"
+dataset = "ely_diagnostics"
+
 [[ratelimits]]
 name = "ELY_RATE_LIMITER"
 namespace_id = "1001"