From e7d0c37c4ed6f7d8d321da73e1d016c258bbf968 Mon Sep 17 00:00:00 2001
From: gsxdsm <gsxdsm@users.noreply.github.com>
Date: Wed, 12 Aug 2026 17:03:11 -0700
Subject: [PATCH] test(sse): drive agent-activity durable poll via env seam
 instead of 2.1s real sleep

Replace the fixed ~2.1s real time-wait in the agent-activity SSE durable
integration test with a bounded FUSION_AGENT_ACTIVITY_POLL_MS env test-seam
(default 2000ms unchanged in production) and poll for the delivered frame.
Removes an FN-5048 real time-wait anti-pattern; production behavior unchanged.
---
 .../src/__tests__/sse-agent-activity.test.ts  | 22 ++++++++++++++-----
 packages/dashboard/src/sse.ts                 | 20 ++++++++++++++++-
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/packages/dashboard/src/__tests__/sse-agent-activity.test.ts b/packages/dashboard/src/__tests__/sse-agent-activity.test.ts
index d5e56c8d25..6dfbc8f8ae 100644
--- a/packages/dashboard/src/__tests__/sse-agent-activity.test.ts
+++ b/packages/dashboard/src/__tests__/sse-agent-activity.test.ts
@@ -289,6 +289,10 @@ pgDescribe("agent activity SSE durable integration", () => {
   afterAll(h.afterAll);
 
   it("delivers an out-of-process-shaped persisted append through the seq tail", async () => {
+    // FNXC:AgentActivityStream 2026-08-12-00:00: drive the real durable poll fast via its
+    // bounded env test-seam instead of sleeping a full 2s production cycle (FN-5048).
+    const priorPollMs = process.env.FUSION_AGENT_ACTIVITY_POLL_MS;
+    process.env.FUSION_AGENT_ACTIVITY_POLL_MS = "20";
     const realCore = await vi.importActual<typeof import("@fusion/core")>("@fusion/core");
     getMaxAgentActivitySeq.mockReset().mockImplementation((layer) => realCore.getMaxAgentActivitySeq(layer));
     queryAgentActivityEvents.mockReset().mockImplementation((layer, query) => realCore.queryAgentActivityEvents(layer, query));
@@ -311,15 +315,23 @@ pgDescribe("agent activity SSE durable integration", () => {
         discriminator: "external-exec-after-connect",
         metadata: { runId: "exec-FN-8864-1234567891-abcd" },
       });
-      // No store.emit: the poll is the delivery guarantee for external writers.
-      await new Promise((resolve) => setTimeout(resolve, 2_100));
-      const frames = response.write.mock.calls
-        .map(([frame]) => String(frame))
-        .filter((frame) => frame.startsWith("event: agent:activity"));
+      // No store.emit: the poll is the delivery guarantee for external writers. Poll for the
+      // frame rather than sleeping a fixed cycle so the test tracks real delivery, not a timer.
+      const agentActivityFrames = () =>
+        response.write.mock.calls
+          .map(([frame]) => String(frame))
+          .filter((frame) => frame.startsWith("event: agent:activity"));
+      const deadline = Date.now() + 5_000;
+      while (agentActivityFrames().length < 1 && Date.now() < deadline) {
+        await new Promise((resolve) => setTimeout(resolve, 20));
+      }
+      const frames = agentActivityFrames();
       expect(frames).toHaveLength(1);
       expect(JSON.parse(frames[0]!.split("data: ")[1]!.trim())).toMatchObject({ seq: "1", taskId: "FN-8864" });
     } finally {
       response.emit("close");
+      if (priorPollMs === undefined) delete process.env.FUSION_AGENT_ACTIVITY_POLL_MS;
+      else process.env.FUSION_AGENT_ACTIVITY_POLL_MS = priorPollMs;
     }
   });
 });
diff --git a/packages/dashboard/src/sse.ts b/packages/dashboard/src/sse.ts
index 09234647a4..f2858a249d 100644
--- a/packages/dashboard/src/sse.ts
+++ b/packages/dashboard/src/sse.ts
@@ -53,6 +53,24 @@ function sseDebug(message: string): void {
   sseLog.debug(message);
 }
 
+/*
+FNXC:AgentActivityStream 2026-08-12-00:00:
+The durable agent-activity seq tail polls every 2s in production — that interval IS the
+cross-process delivery guarantee for short-lived out-of-process writers that never emit an
+in-process nudge. The PG integration test for that path could only prove delivery by sleeping
+a full real poll cycle (~2.1s), which is exactly the kind of real time-wait FN-5048 forbids.
+Expose a bounded env test-seam (FUSION_AGENT_ACTIVITY_POLL_MS) so that test can drive the poll
+fast without weakening the real 2s default or the delivery contract. Read per-connection so a
+test can set it before opening the SSE; clamp to >=10ms so a bad value can never busy-spin.
+*/
+function resolveAgentActivityPollMs(): number {
+  const raw = process.env.FUSION_AGENT_ACTIVITY_POLL_MS?.trim();
+  if (!raw) return 2_000;
+  const parsed = Number(raw);
+  if (!Number.isFinite(parsed) || parsed <= 0) return 2_000;
+  return Math.max(10, Math.floor(parsed));
+}
+
 const SSE_CLIENT_ID_MAX_LENGTH = 128;
 /*
  * FNXC:DashboardSSE 2026-06-23-15:08:
@@ -705,7 +723,7 @@ export function createSSE(
       }
       void drainAgentActivity();
     };
-    const agentActivityPoll = setInterval(onAgentActivityNudge, 2_000);
+    const agentActivityPoll = setInterval(onAgentActivityNudge, resolveAgentActivityPollMs());
     agentActivityPoll.unref?.();
     // --- Event handler definitions ---
     const onCreated = (task: unknown) => {