fix(FN-3187): stabilize agent run log streaming

packages/core/src/__tests__/agent-store.test.ts

@@ -2040,6 +2040,27 @@ describe("AgentStore", () => {
       const completed = await store.getCompletedHeartbeatRuns(agent.id);
       expect(completed.some((r) => r.id === structuredRun.id)).toBe(true);
     });
+
+    it("appendRunLog emits run:log and persists the entry", async () => {
+      const agent = await store.createAgent({ name: "RunLogger", role: "executor" });
+      const run = await store.startHeartbeatRun(agent.id);
+      const onRunLog = vi.fn();
+      store.on("run:log", onRunLog);
+
+      const entry = {
+        timestamp: "2026-01-01T00:00:00.000Z",
+        taskId: "agent-run",
+        text: "streamed output",
+        type: "text" as const,
+      };
+
+      await store.appendRunLog(agent.id, run.id, entry);
+
+      expect(onRunLog).toHaveBeenCalledWith(agent.id, run.id, expect.objectContaining(entry));
+      await expect(store.getRunLogs(agent.id, run.id)).resolves.toEqual([
+        expect.objectContaining(entry),
+      ]);
+    });
   });
 
   // ── blocked state persistence ─────────────────────────────────────

packages/core/src/agent-store.ts

@@ -88,6 +88,8 @@ export interface AgentStoreEvents {
   "agent:assigned": (agent: Agent, taskId: string) => void;
   /** Emitted when a rating is added */
   "rating:added": (rating: AgentRating) => void;
+  /** Emitted when a log entry is appended to a run's JSONL log. */
+  "run:log": (agentId: string, runId: string, entry: AgentLogEntry) => void;
 }
 
 /** Options for AgentStore constructor */
@@ -1838,6 +1840,7 @@ export class AgentStore extends EventEmitter {
     };
     const line = JSON.stringify(safeEntry) + "\n";
     await appendFile(this.runLogPath(agentId, runId), line, "utf-8");
+    this.emit("run:log", agentId, runId, safeEntry);
   }
 
   /**