fix: delimit subsession output from guidance

src/server/sessions/piSessionService.spawnSubsession.test.ts

@@ -804,7 +804,7 @@ describe("PiSessionService", () => {
       await new Promise((resolve) => setTimeout(resolve, 20));
 
       expect(parent.calls.sendCustomMessage[0]?.message.content).toBe(
-        "Subsession child-1 stopped working (idle). Latest output:\n\n(no output)\n\nStill working: child-2. Continue working, or call yield_to_subsessions alone and last at the next join point. Further completion notices arrive automatically; do not poll.",
+        "Subsession child-1 stopped working (idle).\nStill working: child-2. Continue working, or call yield_to_subsessions alone and last at the next join point. Further completion notices arrive automatically; do not poll.\n\n--- SUBSESSION OUTPUT: child-1 ---\n(no output)",
       );
 
       second.session.isStreaming = false;
@@ -812,7 +812,7 @@ describe("PiSessionService", () => {
       await new Promise((resolve) => setTimeout(resolve, 20));
 
       expect(parent.calls.sendCustomMessage[1]?.message.content).toBe(
-        "Subsession child-2 stopped working (idle). Latest output:\n\n(no output)\n\nNo other tracked subsessions are working.",
+        "Subsession child-2 stopped working (idle).\nNo other tracked subsessions are working.\n\n--- SUBSESSION OUTPUT: child-2 ---\n(no output)",
       );
       await service.dispose();
     });

src/server/sessions/piSessionService.ts

@@ -931,7 +931,7 @@ export class PiSessionService {
     const next = workingIds.length === 0
       ? "No other tracked subsessions are working."
       : `Still working: ${workingIds.join(", ")}. Continue working, or call yield_to_subsessions alone and last at the next join point. Further completion notices arrive automatically; do not poll.`;
-    const text = `Subsession ${childId} stopped working (${status}). Latest output:\n\n${preview}\n\n${next}`;
+    const text = `Subsession ${childId} stopped working (${status}).\n${next}\n\n--- SUBSESSION OUTPUT: ${childId} ---\n${preview}`;
     void this.notifyParentOfSubsession(link.parentSessionId, childId, text);
   }
 

src/server/sessions/spawnSubsessionTool.test.ts

@@ -183,7 +183,7 @@ describe("createSubsessionToolDefinitions", () => {
 
     expect(check).toHaveBeenCalledWith("parent-1", "child-1", "/sessions/parent-1.jsonl");
     expect(result.details).toMatchObject({ sessionId: "child-1", status: "idle", finalText: "all done" });
-    expect(firstText(result.content)).toContain("all done");
+    expect(firstText(result.content)).toBe("Subsession child-1 [idle].\n\n--- SUBSESSION OUTPUT: child-1 ---\nall done");
     expect(result.terminate).toBeUndefined();
   });
 
@@ -208,7 +208,7 @@ describe("createSubsessionToolDefinitions", () => {
 
     const result = await checkTool.execute("call-error-check", { sessionId: "child-1" }, undefined, undefined, ctxFor("parent-1", undefined));
 
-    expect(firstText(result.content)).toBe("Subsession child-1 [error]:\n\nchild failed");
+    expect(firstText(result.content)).toBe("Subsession child-1 [error].\n\n--- SUBSESSION OUTPUT: child-1 ---\nchild failed");
     expect(result.terminate).toBeUndefined();
   });
 
@@ -224,15 +224,15 @@ describe("createSubsessionToolDefinitions", () => {
     const read = vi.fn(() => Promise.resolve({
       sessionId: "child-1", cwd: "/repos/a", status: "idle" as const,
       entries: [{ index: 2, role: "assistant" as const, parts: [{ kind: "text" as const, text: "the answer" }] }],
-      total: 5, matched: 1, start: 2, hasMore: false,
+      total: 5, matched: 2, start: 2, hasMore: true,
     }));
     const { read: readTool } = tools({ read });
 
-    const result = await readTool.execute("call-6", { sessionId: "child-1", roles: ["assistant"], maxChars: 200 }, undefined, undefined, ctxFor("parent-1", "/sessions/parent-1.jsonl"));
+    const result = await readTool.execute("call-6", { sessionId: "child-1", roles: ["assistant"], maxChars: 200, limit: 1 }, undefined, undefined, ctxFor("parent-1", "/sessions/parent-1.jsonl"));
 
-    expect(read).toHaveBeenCalledWith("parent-1", "child-1", { roles: ["assistant"], maxChars: 200 }, "/sessions/parent-1.jsonl");
-    expect(result.details).toMatchObject({ sessionId: "child-1", matched: 1 });
-    expect(firstText(result.content)).toContain("the answer");
+    expect(read).toHaveBeenCalledWith("parent-1", "child-1", { roles: ["assistant"], maxChars: 200, limit: 1 }, "/sessions/parent-1.jsonl");
+    expect(result.details).toMatchObject({ sessionId: "child-1", matched: 2 });
+    expect(firstText(result.content)).toBe("Subsession child-1 [idle] — messages 2–2 of 5 (2 matched). Earlier matching messages exist before index 2.\n\n--- SUBSESSION TRANSCRIPT: child-1 ---\n#2 assistant\nthe answer");
     expect(result.terminate).toBeUndefined();
   });
 

src/server/sessions/spawnSubsessionTool.ts

@@ -158,7 +158,7 @@ function renderTranscript(result: SubsessionReadResult): string {
       ? "no messages matched your filters"
       : `no messages in this window (${String(result.matched)} matched outside it)`)
     : `messages ${String(result.start)}–${String(last.index)} of ${String(result.total)} (${String(result.matched)} matched)`;
-  const more = result.hasMore ? `\n\nEarlier matching messages exist before index ${String(result.start)}.` : "";
+  const more = result.hasMore ? ` Earlier matching messages exist before index ${String(result.start)}.` : "";
   // Empty entries with matches means the `before` cursor excluded every match
   // (they all sit at index >= before): the agent paged too far back and should
   // raise `before` or omit it, not page back further.
@@ -167,7 +167,7 @@ function renderTranscript(result: SubsessionReadResult): string {
     : (result.matched === 0
       ? "(no messages matched the filters)"
       : `(no messages before index ${String(result.start)}; all ${String(result.matched)} matches have later indexes)`);
-  return `Subsession ${result.sessionId} [${result.status}] — ${range}:\n\n${body}${more}`;
+  return `Subsession ${result.sessionId} [${result.status}] — ${range}.${more}\n\n--- SUBSESSION TRANSCRIPT: ${result.sessionId} ---\n${body}`;
 }
 
 /**
@@ -235,7 +235,7 @@ export function createSubsessionToolDefinitions(spawningCwd: string, deps: Subse
       const body = result.finalText === "" ? "(no output yet)" : result.finalText;
       const text = result.status === "working"
         ? workingInspectionGuidance(result.sessionId)
-        : `Subsession ${result.sessionId} [${result.status}]:\n\n${body}`;
+        : `Subsession ${result.sessionId} [${result.status}].\n\n--- SUBSESSION OUTPUT: ${result.sessionId} ---\n${body}`;
       return {
         content: [{ type: "text", text }],
         details: result,