diff --git a/server/src/__tests__/heartbeat-run-summary.test.ts b/server/src/__tests__/heartbeat-run-summary.test.ts
index e5d8848d6c..74051ab469 100644
--- a/server/src/__tests__/heartbeat-run-summary.test.ts
+++ b/server/src/__tests__/heartbeat-run-summary.test.ts
@@ -63,6 +63,59 @@ describe("buildHeartbeatRunIssueComment", () => {
   it("returns null when there is no usable final text", () => {
     expect(buildHeartbeatRunIssueComment({ costUsd: 1.2 })).toBeNull();
   });
+
+  it("suppresses raw transcript when the summary reads like inter-tool narration", () => {
+    const narration =
+      "Let me check the issue thread first. I'll fetch the latest comments and then decide what to do next.";
+    const comment = buildHeartbeatRunIssueComment({ summary: narration });
+
+    expect(comment).not.toContain("Let me check");
+    expect(comment).toContain("did not post a summary comment");
+  });
+
+  it("suppresses each narration opener variant", () => {
+    for (const opener of [
+      "Let me look into this.",
+      "I'll start by reading the file.",
+      "I need to inspect the config.",
+      "I can see the problem now.",
+      "Looking at the logs, the error is clear.",
+      "Fetching the run details from the API.",
+      "Checking the current branch state.",
+      "First, I will reproduce the bug.",
+      "I’m going to trace the fallback path.",
+      "Now I'll push the follow-up commit.",
+      "Next, I'll re-run the suite.",
+    ]) {
+      expect(buildHeartbeatRunIssueComment({ summary: opener })).toContain(
+        "did not post a summary comment",
+      );
+    }
+  });
+
+  it("does not treat the apostrophe opener as a regex wildcard", () => {
+    // Prior regex used `i.ll` where `.` matched any char; these must pass through.
+    for (const summary of ["Iall greetings logged.", "I-ll formatting kept."]) {
+      expect(buildHeartbeatRunIssueComment({ summary })).toBe(summary);
+    }
+  });
+
+  it("suppresses over-long fallback summaries even without a narration opener", () => {
+    const comment = buildHeartbeatRunIssueComment({ summary: "x".repeat(1201) });
+    expect(comment).toContain("did not post a summary comment");
+    expect(comment).not.toContain("xxxx");
+  });
+
+  it("posts a clean, in-length summary with no narration opener normally", () => {
+    const summary = "## Summary\n\n- fixed the fallback gate\n- added regression tests";
+    expect(buildHeartbeatRunIssueComment({ summary })).toBe(summary);
+  });
+
+  it("posts a summary exactly at the length cap", () => {
+    const summary = "S" + "x".repeat(1199);
+    expect(summary.length).toBe(1200);
+    expect(buildHeartbeatRunIssueComment({ summary })).toBe(summary);
+  });
 });
 
 describe("mergeHeartbeatRunResultJson", () => {
diff --git a/server/src/services/heartbeat-run-summary.ts b/server/src/services/heartbeat-run-summary.ts
index 479957dce2..cdd1bdeca9 100644
--- a/server/src/services/heartbeat-run-summary.ts
+++ b/server/src/services/heartbeat-run-summary.ts
@@ -92,6 +92,19 @@ export function summarizeHeartbeatRunResultJson(
   return Object.keys(summary).length > 0 ? summary : null;
 }
 
+// The fallback comment is only posted when a run ends without the agent posting
+// its own comment via the API. In that case `resultJson.summary` can be raw
+// inter-tool narration (assistantTexts concatenated by the adapter), which must
+// never be published verbatim to the board — see BRO-1507 / BRO-1516.
+export const MAX_FALLBACK_COMMENT_CHARS = 1200;
+// Apostrophes are matched as a character class so both the straight (') and
+// curly (’) forms count — agents emit either. Openers are narration phrases a
+// declarative status summary would not begin with ("Fixed X", "13/13 pass").
+const NARRATION_OPENERS =
+  /^(let me\b|i['’]ll\b|i['’]m going\b|i need to\b|i can see\b|now i['’]ll\b|next,? i['’]ll\b|looking at\b|fetching\b|checking\b|first,)/i;
+const FALLBACK_WITHHELD_COMMENT =
+  "Run completed. Agent did not post a summary comment this run (transcript withheld — see run log).";
+
 export function buildHeartbeatRunIssueComment(
   resultJson: Record<string, unknown> | null | undefined,
 ): string | null {
@@ -99,10 +112,17 @@ export function buildHeartbeatRunIssueComment(
     return null;
   }
 
-  return (
+  const text =
     readCommentText(resultJson.summary)
     ?? readCommentText(resultJson.result)
-    ?? readCommentText(resultJson.message)
-    ?? null
-  );
+    ?? readCommentText(resultJson.message);
+  if (!text) {
+    return null;
+  }
+
+  if (text.length > MAX_FALLBACK_COMMENT_CHARS || NARRATION_OPENERS.test(text)) {
+    return FALLBACK_WITHHELD_COMMENT;
+  }
+
+  return text;
 }