diff --git a/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.context-engine.test.ts b/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.context-engine.test.ts
index ba23e83c6c06..aa66a4662f73 100644
--- a/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.context-engine.test.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.context-engine.test.ts
@@ -211,6 +211,32 @@ describe("runEmbeddedAttempt context engine sessionKey forwarding", () => {
     vi.restoreAllMocks();
   });
 
+  it("flushes block replies again after compaction retry wait resolves", async () => {
+    const order: string[] = [];
+    let flushCount = 0;
+    const onBlockReplyFlush = vi.fn(async () => {
+      flushCount += 1;
+      order.push(`flush-${flushCount}`);
+    });
+    hoisted.waitForCompactionRetryWithAggregateTimeoutMock.mockImplementation(async () => {
+      order.push("retry-wait");
+      return { timedOut: false };
+    });
+
+    await createContextEngineAttemptRunner({
+      contextEngine: createContextEngineBootstrapAndAssemble(),
+      sessionKey,
+      tempPaths,
+      attemptOverrides: {
+        onBlockReplyFlush,
+      },
+    });
+
+    expect(onBlockReplyFlush).toHaveBeenCalledTimes(2);
+    expect(hoisted.waitForCompactionRetryWithAggregateTimeoutMock).toHaveBeenCalledTimes(1);
+    expect(order).toEqual(["flush-1", "retry-wait", "flush-2"]);
+  });
+
   it("enables Tool Search controls for embedded PI runs when configured", async () => {
     await createContextEngineAttemptRunner({
       contextEngine: {
diff --git a/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.test-support.ts b/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.test-support.ts
index ff60234e6cf2..41bfd9ad70a9 100644
--- a/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.test-support.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.test-support.ts
@@ -32,6 +32,8 @@ type AcquireSessionWriteLockFn =
   typeof import("../../session-write-lock.js").acquireSessionWriteLock;
 type ShouldPreemptivelyCompactBeforePromptFn =
   typeof import("./preemptive-compaction.js").shouldPreemptivelyCompactBeforePrompt;
+type WaitForCompactionRetryWithAggregateTimeoutFn =
+  typeof import("./compaction-retry-aggregate-timeout.js").waitForCompactionRetryWithAggregateTimeout;
 
 type SubscriptionMock = ReturnType<SubscribeEmbeddedPiSessionFn>;
 type UnknownMock = Mock<(...args: unknown[]) => unknown>;
@@ -92,6 +94,7 @@ type AttemptSpawnWorkspaceHoisted = {
     (sessionKey: string | undefined, config: unknown) => number | undefined
   >;
   limitHistoryTurnsMock: Mock<<T>(messages: T, limit: number | undefined) => T>;
+  waitForCompactionRetryWithAggregateTimeoutMock: Mock<WaitForCompactionRetryWithAggregateTimeoutFn>;
   preemptiveCompactionCalls: Parameters<ShouldPreemptivelyCompactBeforePromptFn>[0][];
   systemPromptOverrideTexts: string[];
   sessionManager: SessionManagerMocks;
@@ -191,6 +194,10 @@ const hoisted = vi.hoisted((): AttemptSpawnWorkspaceHoisted => {
   const limitHistoryTurnsMock = vi.fn<<T>(messages: T, limit: number | undefined) => T>(
     (messages) => messages,
   );
+  const waitForCompactionRetryWithAggregateTimeoutMock =
+    vi.fn<WaitForCompactionRetryWithAggregateTimeoutFn>(async () => ({
+      timedOut: false,
+    }));
   const preemptiveCompactionCalls: Parameters<ShouldPreemptivelyCompactBeforePromptFn>[0][] = [];
   const systemPromptOverrideTexts: string[] = [];
   const sessionManager = {
@@ -234,6 +241,7 @@ const hoisted = vi.hoisted((): AttemptSpawnWorkspaceHoisted => {
     detectAndLoadPromptImagesMock,
     getHistoryLimitFromSessionKeyMock,
     limitHistoryTurnsMock,
+    waitForCompactionRetryWithAggregateTimeoutMock,
     preemptiveCompactionCalls,
     systemPromptOverrideTexts,
     sessionManager,
@@ -790,10 +798,9 @@ vi.mock("../utils.js", () => ({
 }));
 
 vi.mock("./compaction-retry-aggregate-timeout.js", () => ({
-  waitForCompactionRetryWithAggregateTimeout: async () => ({
-    timedOut: false,
-    aborted: false,
-  }),
+  waitForCompactionRetryWithAggregateTimeout: (
+    ...args: Parameters<WaitForCompactionRetryWithAggregateTimeoutFn>
+  ) => hoisted.waitForCompactionRetryWithAggregateTimeoutMock(...args),
 }));
 
 vi.mock("./compaction-timeout.js", () => ({
@@ -975,6 +982,9 @@ export function resetEmbeddedAttemptHarness(
   hoisted.runContextEngineMaintenanceMock.mockReset().mockResolvedValue(undefined);
   hoisted.getHistoryLimitFromSessionKeyMock.mockReset().mockReturnValue(undefined);
   hoisted.limitHistoryTurnsMock.mockReset().mockImplementation((messages) => messages);
+  hoisted.waitForCompactionRetryWithAggregateTimeoutMock
+    .mockReset()
+    .mockResolvedValue({ timedOut: false });
   hoisted.preemptiveCompactionCalls.length = 0;
   hoisted.systemPromptOverrideTexts.length = 0;
   hoisted.sessionManager.getLeafEntry.mockReset().mockReturnValue(null);
diff --git a/src/agents/pi-embedded-runner/run/attempt.ts b/src/agents/pi-embedded-runner/run/attempt.ts
index 5b70a28df78f..22795bdd0907 100644
--- a/src/agents/pi-embedded-runner/run/attempt.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.ts
@@ -4483,6 +4483,11 @@ export async function runEmbeddedAttempt(
                   `proceeding with pre-compaction state runId=${params.runId} sessionId=${params.sessionId}`,
               );
             }
+          } else if (onBlockReplyFlush) {
+            // Retry-generated blocks can still be draining when the compaction
+            // retry wait resolves; this second drain is idempotent when no new
+            // blocks were produced.
+            await onBlockReplyFlush();
           }
         } catch (err) {
           if (isRunnerAbortError(err)) {