refactor: simplify subagent failure context helpers

src/agents/subagent-announce-output.ts

@@ -73,17 +73,7 @@ export function withSubagentOutcomeTiming(
     startedAt?: number;
     endedAt?: number;
   },
-): SubagentRunOutcome;
-export function withSubagentOutcomeTiming(
-  outcome: SubagentRunOutcome | undefined,
-  timing: {
-    startedAt?: number;
-    endedAt?: number;
-  },
-): SubagentRunOutcome | undefined {
-  if (!outcome) {
-    return undefined;
-  }
+): SubagentRunOutcome {
   const startedAt = readFiniteNumber(timing.startedAt) ?? readFiniteNumber(outcome.startedAt);
   const endedAt = readFiniteNumber(timing.endedAt) ?? readFiniteNumber(outcome.endedAt);
   const nextTiming: Pick<SubagentRunOutcome, "startedAt" | "endedAt" | "elapsedMs"> = {};
@@ -343,15 +333,15 @@ export function applySubagentWaitOutcome(params: {
     next.endedAt = params.wait.endedAt;
   }
   const waitError = typeof params.wait?.error === "string" ? params.wait.error : undefined;
+  let outcome = next.outcome;
   if (params.wait?.status === "timeout") {
-    next.outcome = withSubagentOutcomeTiming({ status: "timeout" }, next);
+    outcome = { status: "timeout" };
   } else if (params.wait?.status === "error") {
-    next.outcome = withSubagentOutcomeTiming({ status: "error", error: waitError }, next);
+    outcome = { status: "error", error: waitError };
   } else if (params.wait?.status === "ok") {
-    next.outcome = withSubagentOutcomeTiming({ status: "ok" }, next);
-  } else {
-    next.outcome = withSubagentOutcomeTiming(next.outcome, next);
+    outcome = { status: "ok" };
   }
+  next.outcome = outcome ? withSubagentOutcomeTiming(outcome, next) : undefined;
   return next;
 }
 

src/agents/tools/sessions-spawn-tool.ts

@@ -53,6 +53,16 @@ function summarizeError(err: unknown): string {
   return "error";
 }
 
+function addRoleToFailureResult<T extends { status: string }>(
+  result: T,
+  role: string | undefined,
+): T | (T & { role: string }) {
+  if (!role || (result.status !== "error" && result.status !== "forbidden")) {
+    return result;
+  }
+  return { ...result, role };
+}
+
 function resolveTrackedSpawnMode(params: {
   requestedMode?: "run" | "session";
   threadRequested: boolean;
@@ -313,10 +323,7 @@ export function createSessionsSpawnTool(
             });
           }
         }
-        const isAcpFailure = result.status === "error" || result.status === "forbidden";
-        return jsonResult(
-          isAcpFailure && requestedAgentId ? { ...result, role: requestedAgentId } : result,
-        );
+        return jsonResult(addRoleToFailureResult(result, requestedAgentId));
       }
 
       const result = await spawnSubagentDirect(
@@ -354,10 +361,7 @@ export function createSessionsSpawnTool(
         },
       );
 
-      const isSubagentFailure = result.status === "error" || result.status === "forbidden";
-      return jsonResult(
-        isSubagentFailure && requestedAgentId ? { ...result, role: requestedAgentId } : result,
-      );
+      return jsonResult(addRoleToFailureResult(result, requestedAgentId));
     },
   };
 }