fix: add periodic flush and graceful shutdown for server-side telemetry

The TelemetryClient only flushed at 50 events, so the server silently
lost all queued telemetry on restart. Add startPeriodicFlush/stop methods
to TelemetryClient, wire up 60s periodic flush in server initTelemetry,
and flush on SIGTERM/SIGINT before exit.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/shared/src/telemetry/client.ts

@@ -18,6 +18,7 @@ export class TelemetryClient {
   private readonly version: string;
   private readonly sessionId: string;
   private state: TelemetryState | null = null;
+  private flushInterval: ReturnType<typeof setInterval> | null = null;
 
   constructor(config: TelemetryConfig, stateFactory: () => TelemetryState, version: string) {
     this.config = config;
@@ -68,6 +69,24 @@ export class TelemetryClient {
     }
   }
 
+  startPeriodicFlush(intervalMs: number = 60_000): void {
+    if (this.flushInterval) return;
+    this.flushInterval = setInterval(() => {
+      void this.flush();
+    }, intervalMs);
+    // Allow the process to exit even if the interval is still active
+    if (typeof this.flushInterval === "object" && "unref" in this.flushInterval) {
+      this.flushInterval.unref();
+    }
+  }
+
+  stop(): void {
+    if (this.flushInterval) {
+      clearInterval(this.flushInterval);
+      this.flushInterval = null;
+    }
+  }
+
   hashPrivateRef(value: string): string {
     const state = this.getState();
     return createHash("sha256")

server/src/__tests__/telemetry-client-flush.test.ts

@@ -0,0 +1,66 @@
+import { describe, expect, it, vi, beforeEach, afterEach } from "vitest";
+import { TelemetryClient } from "../../../packages/shared/src/telemetry/client.js";
+import type { TelemetryConfig, TelemetryState } from "../../../packages/shared/src/telemetry/types.js";
+
+function makeClient(config?: Partial<TelemetryConfig>) {
+  const merged: TelemetryConfig = { enabled: true, endpoint: "http://localhost:9999/ingest", ...config };
+  const state: TelemetryState = {
+    installId: "test-install",
+    salt: "test-salt",
+    createdAt: "2026-01-01T00:00:00Z",
+    firstSeenVersion: "0.0.0",
+  };
+  return new TelemetryClient(merged, () => state, "0.0.0-test");
+}
+
+describe("TelemetryClient periodic flush", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.stubGlobal("fetch", vi.fn().mockResolvedValue({ ok: true }));
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+    vi.restoreAllMocks();
+  });
+
+  it("flushes queued events on interval", async () => {
+    const client = makeClient();
+    client.startPeriodicFlush(1000);
+
+    client.track("install.started");
+    expect(fetch).not.toHaveBeenCalled();
+
+    await vi.advanceTimersByTimeAsync(1000);
+    expect(fetch).toHaveBeenCalledTimes(1);
+
+    // Second tick with no new events — no additional call
+    await vi.advanceTimersByTimeAsync(1000);
+    expect(fetch).toHaveBeenCalledTimes(1);
+
+    // New event gets flushed on next tick
+    client.track("install.started");
+    await vi.advanceTimersByTimeAsync(1000);
+    expect(fetch).toHaveBeenCalledTimes(2);
+
+    client.stop();
+  });
+
+  it("stop() prevents further flushes", async () => {
+    const client = makeClient();
+    client.startPeriodicFlush(1000);
+
+    client.track("install.started");
+    client.stop();
+
+    await vi.advanceTimersByTimeAsync(2000);
+    expect(fetch).not.toHaveBeenCalled();
+  });
+
+  it("startPeriodicFlush is idempotent", () => {
+    const client = makeClient();
+    client.startPeriodicFlush(1000);
+    client.startPeriodicFlush(1000); // should not throw or double-fire
+    client.stop();
+  });
+});

server/src/index.ts

@@ -39,7 +39,7 @@ import { createStorageServiceFromConfig } from "./storage/index.js";
 import { printStartupBanner } from "./startup-banner.js";
 import { getBoardClaimWarningUrl, initializeBoardClaimChallenge } from "./board-claim.js";
 import { maybePersistWorktreeRuntimePorts } from "./worktree-config.js";
-import { initTelemetry } from "./telemetry.js";
+import { initTelemetry, getTelemetryClient } from "./telemetry.js";
 
 type BetterAuthSessionUser = {
   id: string;
@@ -728,18 +728,26 @@ export async function startServer(): Promise<StartedServer> {
     });
   });
   
-  if (embeddedPostgres && embeddedPostgresStartedByThisProcess) {
+  {
     const shutdown = async (signal: "SIGINT" | "SIGTERM") => {
-      logger.info({ signal }, "Stopping embedded PostgreSQL");
-      try {
-        await embeddedPostgres?.stop();
-      } catch (err) {
-        logger.error({ err }, "Failed to stop embedded PostgreSQL cleanly");
-      } finally {
-        process.exit(0);
+      const telemetryClient = getTelemetryClient();
+      if (telemetryClient) {
+        telemetryClient.stop();
+        await telemetryClient.flush();
       }
+
+      if (embeddedPostgres && embeddedPostgresStartedByThisProcess) {
+        logger.info({ signal }, "Stopping embedded PostgreSQL");
+        try {
+          await embeddedPostgres?.stop();
+        } catch (err) {
+          logger.error({ err }, "Failed to stop embedded PostgreSQL cleanly");
+        }
+      }
+
+      process.exit(0);
     };
-  
+
     process.once("SIGINT", () => {
       void shutdown("SIGINT");
     });

server/src/telemetry.ts

@@ -21,6 +21,7 @@ export function initTelemetry(fileConfig?: { enabled?: boolean }): TelemetryClie
     () => loadOrCreateState(stateDir, serverVersion),
     serverVersion,
   );
+  client.startPeriodicFlush(60_000);
   return client;
 }