Compaction Runner: emit transcript updates post-compact (#25558)

Merged via squash.

Prepared head SHA: 8a858436ed
Co-authored-by: rodrigouroz <384037+rodrigouroz@users.noreply.github.com>
Co-authored-by: jalehman <550978+jalehman@users.noreply.github.com>
Reviewed-by: @jalehman

src/agents/pi-embedded-runner/compact.hooks.test.ts

@@ -1,4 +1,5 @@
 import { beforeEach, describe, expect, it, vi } from "vitest";
+import { onSessionTranscriptUpdate } from "../../sessions/transcript-events.js";
 
 const {
   hookRunner,
@@ -430,6 +431,26 @@ describe("compactEmbeddedPiSessionDirect hooks", () => {
       tokenCount: 0,
     });
   });
+  it("emits a transcript update after successful compaction", async () => {
+    const listener = vi.fn();
+    const cleanup = onSessionTranscriptUpdate(listener);
+
+    try {
+      const result = await compactEmbeddedPiSessionDirect({
+        sessionId: "session-1",
+        sessionKey: "agent:main:session-1",
+        sessionFile: "  /tmp/session.jsonl  ",
+        workspaceDir: "/tmp",
+        customInstructions: "focus on decisions",
+      });
+
+      expect(result.ok).toBe(true);
+      expect(listener).toHaveBeenCalledTimes(1);
+      expect(listener).toHaveBeenCalledWith({ sessionFile: "/tmp/session.jsonl" });
+    } finally {
+      cleanup();
+    }
+  });
 
   it("registers the Ollama api provider before compaction", async () => {
     resolveModelMock.mockReturnValue({

src/agents/pi-embedded-runner/compact.ts

@@ -21,6 +21,7 @@ import { generateSecureToken } from "../../infra/secure-random.js";
 import { getGlobalHookRunner } from "../../plugins/hook-runner-global.js";
 import { type enqueueCommand, enqueueCommandInLane } from "../../process/command-queue.js";
 import { isCronSessionKey, isSubagentSessionKey } from "../../routing/session-key.js";
+import { emitSessionTranscriptUpdate } from "../../sessions/transcript-events.js";
 import { resolveSignalReactionLevel } from "../../signal/reaction-level.js";
 import { resolveTelegramInlineButtonsScope } from "../../telegram/inline-buttons.js";
 import { resolveTelegramReactionLevel } from "../../telegram/reaction-level.js";
@@ -808,6 +809,7 @@ export async function compactEmbeddedPiSessionDirect(
         const result = await compactWithSafetyTimeout(() =>
           session.compact(params.customInstructions),
         );
+        emitSessionTranscriptUpdate(params.sessionFile);
         // Estimate tokens after compaction by summing token estimates for remaining messages
         let tokensAfter: number | undefined;
         try {