fix(agents): retry silent subagent completion handoffs

qa/scenarios/agents/subagent-fanout-synthesis.yaml

@@ -76,6 +76,15 @@ flow:
                               - ref: env
                               - 120000
                           - call: reset
+                          - set: alphaLabel
+                            value:
+                              expr: "env.providerMode === 'mock-openai' ? config.expectedChildLabels[0] : `${config.expectedChildLabels[0]}-${attempt}`"
+                          - set: betaLabel
+                            value:
+                              expr: "env.providerMode === 'mock-openai' ? config.expectedChildLabels[1] : `${config.expectedChildLabels[1]}-${attempt}`"
+                          - set: prompt
+                            value:
+                              expr: "`Subagent fanout synthesis check: delegate exactly two bounded subagents sequentially using sessions_spawn, not ACP.\nFirst spawn exactly one child with label ${alphaLabel} and task: verify that \\`HEARTBEAT.md\\` exists and reply exactly \\`ok\\` if it does. Wait for that child to finish.\nThen spawn exactly one child with label ${betaLabel} and task: verify that \\`repo/qa/scenarios/agents/subagent-fanout-synthesis.yaml\\` exists and reply exactly \\`ok\\` if it does. Wait for that child to finish.\nDo not spawn any more children after ${betaLabel} finishes.\nThen reply with exactly these two lines and nothing else:\nsubagent-1: ok\nsubagent-2: ok`"
                           - set: sessionKey
                             value:
                               expr: "`agent:qa:fanout:${attempt}:${randomUUID().slice(0, 8)}`"
@@ -85,7 +94,7 @@ flow:
                               - sessionKey:
                                   ref: sessionKey
                                 message:
-                                  expr: config.prompt
+                                  ref: prompt
                                 timeoutMs:
                                   expr: liveTurnTimeoutMs(env, 90000)
                           - call: waitForAgentHistoryReply
@@ -110,10 +119,10 @@ flow:
                                     expr: "Object.values(store).filter((entry) => entry.spawnedBy === sessionKey)"
                                 - set: sawAlpha
                                   value:
-                                    expr: "childRows.some((entry) => entry.label === config.expectedChildLabels[0])"
+                                    expr: "childRows.some((entry) => entry.label === alphaLabel)"
                                 - set: sawBeta
                                   value:
-                                    expr: "childRows.some((entry) => entry.label === config.expectedChildLabels[1])"
+                                    expr: "childRows.some((entry) => entry.label === betaLabel)"
                                 - assert:
                                     expr: "sawAlpha && sawBeta"
                                     message:
@@ -159,10 +168,10 @@ flow:
                                     expr: "Object.values(timeoutStore).filter((entry) => entry.spawnedBy === sessionKey)"
                                 - set: timeoutSawAlpha
                                   value:
-                                    expr: "timeoutChildRows.some((entry) => entry.label === config.expectedChildLabels[0])"
+                                    expr: "timeoutChildRows.some((entry) => entry.label === alphaLabel)"
                                 - set: timeoutSawBeta
                                   value:
-                                    expr: "timeoutChildRows.some((entry) => entry.label === config.expectedChildLabels[1])"
+                                    expr: "timeoutChildRows.some((entry) => entry.label === betaLabel)"
                                 - set: timeoutSpawnRequests
                                   value:
                                     expr: "[...(await fetchJson(`${env.mock.baseUrl}/debug/requests`))].filter((request) => request.plannedToolName === 'sessions_spawn' && /subagent fanout synthesis check/i.test(String(request.allInputText ?? '')))"

src/agents/subagent-announce-delivery.test.ts

@@ -1548,7 +1548,7 @@ describe("deliverSubagentAnnouncement completion delivery", () => {
     },
   );
 
-  it("accepts session-only completion handoff when the in-process agent intentionally replies NO_REPLY", async () => {
+  it("accepts non-subagent session-only completion handoff when the in-process agent intentionally replies NO_REPLY", async () => {
     const dispatchGatewayMethodInProcess = createInProcessGatewayMock({
       result: {
         payloads: [{ text: "NO_REPLY" }],
@@ -1572,6 +1572,7 @@ describe("deliverSubagentAnnouncement completion delivery", () => {
       expectsCompletionMessage: true,
       bestEffortDeliver: true,
       directIdempotencyKey: "announce-local-silent",
+      sourceTool: "agent_harness_task",
     });
 
     expectRecordFields(result, {
@@ -1586,6 +1587,47 @@ describe("deliverSubagentAnnouncement completion delivery", () => {
     });
   });
 
+  it("rejects session-only subagent completion handoff when the parent only replies NO_REPLY", async () => {
+    const dispatchGatewayMethodInProcess = createInProcessGatewayMock({
+      result: {
+        payloads: [{ text: "NO_REPLY" }],
+      },
+    });
+    testing.setDepsForTest({
+      dispatchGatewayMethodInProcess,
+      getRequesterSessionActivity: () => ({
+        sessionId: "requester-session-local",
+        isActive: false,
+      }),
+      getRuntimeConfig: () => ({}) as never,
+    });
+
+    const result = await deliverSubagentAnnouncement({
+      requesterSessionKey: "agent:main:local-session",
+      targetRequesterSessionKey: "agent:main:local-session",
+      triggerMessage: "child done",
+      steerMessage: "child done",
+      requesterIsSubagent: false,
+      expectsCompletionMessage: true,
+      bestEffortDeliver: true,
+      directIdempotencyKey: "announce-local-subagent-silent",
+      sourceTool: "subagent_announce",
+    });
+
+    expectRecordFields(result, {
+      delivered: false,
+      path: "direct",
+      reason: "visible_reply_missing",
+      error: "completion agent did not produce a visible reply",
+    });
+    expectInProcessAgentParams(dispatchGatewayMethodInProcess, {
+      deliver: false,
+      channel: undefined,
+      to: undefined,
+      bestEffortDeliver: true,
+    });
+  });
+
   it.each([
     {
       name: "accepted session spawn",

src/agents/subagent-announce-delivery.ts

@@ -667,6 +667,46 @@ function hasVisibleGatewayAgentPayload(response: unknown): boolean {
   );
 }
 
+function hasVisibleNonSilentGatewayAgentPayload(response: unknown): boolean {
+  const result = getGatewayAgentResult(response);
+  if (!result) {
+    return false;
+  }
+  if (hasMessagingToolDeliveryEvidence(result)) {
+    return true;
+  }
+  const payloads = Array.isArray(result.payloads) ? result.payloads : [];
+  return payloads.some(isVisibleNonSilentGatewayAgentPayload);
+}
+
+function isVisibleNonSilentGatewayAgentPayload(payload: unknown): boolean {
+  if (!payload || typeof payload !== "object" || Array.isArray(payload)) {
+    return false;
+  }
+  const record = payload as {
+    text?: unknown;
+    mediaUrl?: unknown;
+    mediaUrls?: unknown;
+    presentation?: unknown;
+    interactive?: unknown;
+    channelData?: unknown;
+  };
+  if (
+    record.mediaUrl ||
+    (Array.isArray(record.mediaUrls) && record.mediaUrls.length > 0) ||
+    record.presentation ||
+    record.interactive ||
+    record.channelData
+  ) {
+    return true;
+  }
+  return (
+    typeof record.text === "string" &&
+    record.text.trim() !== "" &&
+    !isSilentReplyPayloadText(record.text, SILENT_REPLY_TOKEN)
+  );
+}
+
 function hasGatewayAgentMessagingToolDeliveryEvidence(response: unknown): boolean {
   const result = getGatewayAgentResult(response);
   return Boolean(result && hasMessagingToolDeliveryEvidence(result));
@@ -1613,13 +1653,21 @@ async function sendSubagentAnnounceDirectly(params: {
         error: "completion agent did not use the message tool for message-tool-only delivery",
       };
     }
+    const hasVisibleCompletionReply =
+      hasVisibleNonSilentGatewayAgentPayload(directAnnounceResponse);
+    const hasCompletionSideEffect =
+      hasGatewayAgentCompletionSideEffectEvidence(directAnnounceResponse);
+    const hasIntentionalSilentCompletionReply =
+      hasIntentionalSilentGatewayAgentPayload(directAnnounceResponse);
+    const acceptsIntentionalSilentCompletion =
+      hasIntentionalSilentCompletionReply && !isSubagentCompletion;
     if (
       params.expectsCompletionMessage &&
       !shouldDeliverAgentFinal &&
       !requiresMessageToolDelivery &&
-      !hasVisibleGatewayAgentPayload(directAnnounceResponse) &&
-      !hasGatewayAgentCompletionSideEffectEvidence(directAnnounceResponse) &&
-      !hasIntentionalSilentGatewayAgentPayload(directAnnounceResponse)
+      !hasVisibleCompletionReply &&
+      !hasCompletionSideEffect &&
+      !acceptsIntentionalSilentCompletion
     ) {
       return {
         delivered: false,

src/agents/subagent-announce.ts

@@ -93,7 +93,7 @@ function buildAnnounceReplyInstruction(params: {
     return `Convert this completion into a concise internal orchestration update for your parent agent in your own words. Keep this internal context private (don't mention system/log/stats/session details or announce type). If this result is duplicate or no update is needed, reply ONLY: ${SILENT_REPLY_TOKEN}.`;
   }
   if (params.expectsCompletionMessage) {
-    return `A completed ${params.announceType} is ready for parent review. Review/verify the result above before deciding whether the original task is done. If additional action is required, continue the task or record a follow-up; otherwise send a truthful user-facing update. Keep this internal context private (don't mention system/log/stats/session details or announce type). Reply ONLY: ${SILENT_REPLY_TOKEN} when no user-facing update is needed.`;
+    return `A completed ${params.announceType} is ready for parent review. Review/verify the result above before deciding whether the original task is done. If additional action is required, continue the task or record a follow-up; otherwise send a truthful user-facing update. Keep this internal context private (don't mention system/log/stats/session details or announce type). Reply ONLY: ${SILENT_REPLY_TOKEN} only when this exact result is already visible to the user in this same turn.`;
   }
   return `A completed ${params.announceType} is ready for parent review. Review/verify the result above before deciding whether the original task is done. If additional action is required, continue the task or record a follow-up; otherwise send a truthful user-facing update. Keep this internal context private (don't mention system/log/stats/session details or announce type), and do not copy the internal event text verbatim. Reply ONLY: ${SILENT_REPLY_TOKEN} if this exact result was already delivered to the user in this same turn.`;
 }