Preserve all four sub-agent report headings with None. for empty sections

src/agent/prompts.test.ts

@@ -128,6 +128,18 @@ describe("shared discipline block appears exactly once per built prompt", () =>
   });
 });
 
+describe("sub-agent report contract", () => {
+  it("requires all four headings with None. instead of omitting empty sections", () => {
+    const prompt = buildSubAgentSystemPrompt(undefined, undefined, undefined, {
+      orchestrator: false,
+      grokAntiThrash: false,
+    });
+    expect(prompt).not.toContain("omit empty sections");
+    expect(prompt).toMatch(/emit all four headings/);
+    expect(prompt).toContain('"None."');
+  });
+});
+
 describe("shared verification guidance", () => {
   it("requires evidence-carrying verification in worker prompts", () => {
     const prompt = buildSubAgentSystemPrompt(undefined, undefined, undefined, {

src/agent/prompts.ts

@@ -441,7 +441,7 @@ export function buildSubAgentReportContract(
     "- Stick to the dispatch brief. Do not invent scope or wander into unrelated work.",
     "- If the brief lists Success criteria, treat them as the done-definition: when all are met (or you are blocked), stop calling tools and emit the report envelope. Do not keep tooling past done.",
     "- If the brief lists Do not, respect those constraints; do not invent scope outside Intent / Do not.",
-    "- When done, stop calling tools and reply with ONLY this markdown envelope (prose inside each section is fine; omit empty sections rather than inventing content):",
+    '- When done, stop calling tools and reply with ONLY this markdown envelope (prose inside each section is fine; emit all four headings every time in this order, writing "None." under a heading with nothing to report rather than dropping it):',
     "",
     "## Summary",
     "One or two sentences: what you accomplished or concluded.",

src/subagent/index.test.ts

@@ -692,6 +692,9 @@ describe("sub-agent stop helpers", () => {
     const cancelledParsedEmpty = parseSubAgentReport(emptyCancelled);
     expect(cancelledParsedEmpty.findings).toContain("no partial findings");
     expect(emptyCancelled.toLowerCase()).not.toContain("summarize progress");
+    // Empty Paths still renders its heading so the envelope stays complete.
+    expect(hasReportEnvelope(emptyCancelled)).toBe(true);
+    expect(emptyCancelled).toContain("## Paths\nNone.");
 
     // Nested agent envelope must not clobber the outer cancelled Summary when
     // runSubAgent re-parses the forced stop.
@@ -828,6 +831,25 @@ describe("sub-agent stop helpers", () => {
     expect(withPathsParsed.findings).toContain("src/a.ts");
   });
 
+  test("round-trip preserves the envelope when a section body is empty", () => {
+    const reply = [
+      "## Summary",
+      "Did the work.",
+      "",
+      "## Findings",
+      "Touched the gate.",
+      "",
+      "## Blockers",
+      "",
+      "## Paths",
+      "src/gate.ts",
+    ].join("\n");
+    expect(hasReportEnvelope(reply)).toBe(true);
+    const roundTripped = formatSubAgentReport(parseSubAgentReport(reply));
+    expect(hasReportEnvelope(roundTripped)).toBe(true);
+    expect(parseSubAgentReport(roundTripped).blockers).toBe("None.");
+  });
+
   test("forcedStopReport renders a Stopped line for display; classification uses the typed reason", () => {
     expect(
       forcedStopReport("cancelled", "partial", { detail: "Session closed" }),

src/subagent/report.ts

@@ -264,15 +264,15 @@ export function formatSubAgentReport(report: SubAgentReport): string {
   lines.push(
     "## Summary",
     report.summary.length > 0 ? report.summary : "(no summary)",
+    "",
+    "## Findings",
+    report.findings.length > 0 ? report.findings : "None.",
+    "",
+    "## Blockers",
+    report.blockers.length > 0 ? report.blockers : "None.",
+    "",
+    "## Paths",
+    report.paths.length > 0 ? report.paths : "None.",
   );
-  if (report.findings.length > 0) {
-    lines.push("", "## Findings", report.findings);
-  }
-  if (report.blockers.length > 0) {
-    lines.push("", "## Blockers", report.blockers);
-  }
-  if (report.paths.length > 0) {
-    lines.push("", "## Paths", report.paths);
-  }
   return lines.join("\n");
 }