feat(FN-2083): merge fusion/fn-2083

packages/engine/src/agent-logger.test.ts

@@ -344,4 +344,116 @@ describe("AgentLogger", () => {
     await vi.advanceTimersByTimeAsync(0);
     expect(store.appendAgentLog).toHaveBeenCalledWith("FN-018", "Bash", "tool_result", undefined, "merger");
   });
+
+  describe("persistence failure observability", () => {
+    const warningFor = (warnSpy: ReturnType<typeof vi.spyOn>): string => {
+      return warnSpy.mock.calls.map((call) => call.map((arg) => String(arg)).join(" ")).join("\n");
+    };
+
+    it("text flush failure logs structured warning", async () => {
+      const store = {
+        appendAgentLog: vi.fn().mockRejectedValue(new Error("ENOSPC: no space left on device")),
+      } as unknown as TaskStore;
+      const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+      const logger = new AgentLogger({
+        store,
+        taskId: "FN-2083-TEXT",
+        flushSizeBytes: 1,
+      });
+
+      logger.onText("some text");
+      await vi.advanceTimersByTimeAsync(0);
+
+      const warning = warningFor(warnSpy);
+      expect(warning).toContain("[agent-logger]");
+      expect(warning).toContain("FN-2083-TEXT");
+      expect(warning).toContain("ENOSPC");
+
+      warnSpy.mockRestore();
+    });
+
+    it("thinking flush failure logs structured warning", async () => {
+      const store = {
+        appendAgentLog: vi.fn().mockRejectedValue(new Error("ENOSPC: no space left on device")),
+      } as unknown as TaskStore;
+      const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+      const logger = new AgentLogger({
+        store,
+        taskId: "FN-2083-THINK",
+        flushSizeBytes: 1,
+      });
+
+      logger.onThinking("deep thought");
+      await vi.advanceTimersByTimeAsync(0);
+
+      const warning = warningFor(warnSpy);
+      expect(warning).toContain("[agent-logger]");
+      expect(warning).toContain("FN-2083-THINK");
+      expect(warning).toContain("thinking");
+      expect(warning).toContain("ENOSPC");
+
+      warnSpy.mockRestore();
+    });
+
+    it("tool-start persistence failure logs structured warning", async () => {
+      const store = {
+        appendAgentLog: vi.fn().mockRejectedValue(new Error("EACCES: permission denied")),
+      } as unknown as TaskStore;
+      const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+      const logger = new AgentLogger({ store, taskId: "FN-2083-TOOL-START" });
+
+      logger.onToolStart("Bash", { command: "ls" });
+      await vi.advanceTimersByTimeAsync(0);
+
+      const warning = warningFor(warnSpy);
+      expect(warning).toContain("[agent-logger]");
+      expect(warning).toContain("FN-2083-TOOL-START");
+      expect(warning).toContain("Bash");
+      expect(warning).toContain("EACCES");
+
+      warnSpy.mockRestore();
+    });
+
+    it("tool-end persistence failure logs structured warning", async () => {
+      const store = {
+        appendAgentLog: vi.fn().mockRejectedValue(new Error("EPERM: operation not permitted")),
+      } as unknown as TaskStore;
+      const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+      const logger = new AgentLogger({ store, taskId: "FN-2083-TOOL-END" });
+
+      logger.onToolEnd("Bash", false, "output");
+      await vi.advanceTimersByTimeAsync(0);
+
+      const warning = warningFor(warnSpy);
+      expect(warning).toContain("[agent-logger]");
+      expect(warning).toContain("FN-2083-TOOL-END");
+      expect(warning).toContain("EPERM");
+
+      warnSpy.mockRestore();
+    });
+
+    it("flush() propagates text and thinking warnings", async () => {
+      const store = {
+        appendAgentLog: vi.fn().mockRejectedValue(new Error("ENOSPC: no space left on device")),
+      } as unknown as TaskStore;
+      const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+      const logger = new AgentLogger({
+        store,
+        taskId: "FN-2083-FLUSH",
+        flushSizeBytes: 1024,
+      });
+
+      logger.onText("text");
+      logger.onThinking("thought");
+      await logger.flush();
+
+      const warning = warningFor(warnSpy);
+      expect(warnSpy).toHaveBeenCalledTimes(2);
+      expect(warning).toContain("[agent-logger]");
+      expect(warning).toContain("FN-2083-FLUSH");
+      expect(warning).toContain("ENOSPC");
+
+      warnSpy.mockRestore();
+    });
+  });
 });

packages/engine/src/agent-logger.ts

@@ -1,10 +1,13 @@
 import type { TaskStore, AgentRole } from "@fusion/core";
+import { createLogger } from "./logger.js";
 
 /** Default byte threshold before an automatic flush. */
 const FLUSH_SIZE_BYTES = 1024;
 /** Default timer interval (ms) for periodic flush of small writes. */
 const FLUSH_INTERVAL_MS = 500;
 
+const log = createLogger("agent-logger");
+
 /**
  * Produce a human-readable summary from tool arguments.
  * Returns the full argument value without truncation.
@@ -147,7 +150,14 @@ export class AgentLogger {
     if (this.thinkingFlushTimer) { clearTimeout(this.thinkingFlushTimer); this.thinkingFlushTimer = null; }
     this.flushThinkingBuffer();
     const detail = summarizeToolArgs(name, args);
-    this.store.appendAgentLog(this.taskId, name, "tool", detail, this.agent).catch(() => {});
+    this.store.appendAgentLog(this.taskId, name, "tool", detail, this.agent).catch((err) => {
+      log.warn(
+        "Failed to persist tool-start log for task %s (tool: %s): %s",
+        this.taskId,
+        name,
+        err instanceof Error ? err.message : String(err),
+      );
+    });
   }
 
   /**
@@ -165,7 +175,15 @@ export class AgentLogger {
       const str = typeof result === "string" ? result : JSON.stringify(result);
       detail = str.length > 500 ? str.slice(0, 500) + "…" : str;
     }
-    this.store.appendAgentLog(this.taskId, name, type, detail, this.agent).catch(() => {});
+    this.store.appendAgentLog(this.taskId, name, type, detail, this.agent).catch((err) => {
+      log.warn(
+        "Failed to persist tool-end log for task %s (tool: %s, type: %s): %s",
+        this.taskId,
+        name,
+        type,
+        err instanceof Error ? err.message : String(err),
+      );
+    });
   }
 
   /**
@@ -185,8 +203,12 @@ export class AgentLogger {
     if (this.textBuffer.length === 0) return Promise.resolve();
     const chunk = this.textBuffer;
     this.textBuffer = "";
-    return this.store.appendAgentLog(this.taskId, chunk, "text", undefined, this.agent).catch(() => {
+    return this.store.appendAgentLog(this.taskId, chunk, "text", undefined, this.agent).catch((err) => {
-      /* best-effort persistence */
+      log.warn(
+        "Failed to persist text log for task %s: %s",
+        this.taskId,
+        err instanceof Error ? err.message : String(err),
+      );
     });
   }
 
@@ -194,8 +216,12 @@ export class AgentLogger {
     if (this.thinkingBuffer.length === 0) return Promise.resolve();
     const chunk = this.thinkingBuffer;
     this.thinkingBuffer = "";
-    return this.store.appendAgentLog(this.taskId, chunk, "thinking", undefined, this.agent).catch(() => {
+    return this.store.appendAgentLog(this.taskId, chunk, "thinking", undefined, this.agent).catch((err) => {
-      /* best-effort persistence */
+      log.warn(
+        "Failed to persist thinking log for task %s: %s",
+        this.taskId,
+        err instanceof Error ? err.message : String(err),
+      );
     });
   }