diff --git a/src/lib/actions/sandbox/logs.test.ts b/src/lib/actions/sandbox/logs.test.ts
index 903d0a7efd3..bcc3cfbc182 100644
--- a/src/lib/actions/sandbox/logs.test.ts
+++ b/src/lib/actions/sandbox/logs.test.ts
@@ -219,4 +219,27 @@ describe("showSandboxLogsWithDeps", () => {
     expect(guidance).toHaveBeenCalledWith("alpha", { retryCommand: "logs" });
     expect(result.calls).toEqual([]);
   });
+
+  it("surfaces a sparse gateway breadcrumb when OpenShell output dominates the tail", () => {
+    const gatewayStdout = [
+      "[1779488800.000] [gateway] starting HTTP server",
+      "[1779488815.000] [telegram] [default] bridge did not start within 15s; check channels.telegram.enabled, plugin entries, and gateway log",
+    ].join("\n");
+    const openshellStdout = Array.from(
+      { length: 200 },
+      (_v, i) => `[${1779488900 + i}.000] [sandbox] [INFO ] line ${i}`,
+    ).join("\n");
+    const result = captureLogsRun(
+      { follow: false, lines: "200", since: null },
+      {
+        settings: { status: 0 },
+        sandbox: { status: 0, stdout: `${gatewayStdout}\n` },
+        logs: { status: 0, stdout: `${openshellStdout}\n` },
+      },
+    );
+
+    expect(result.exitCode).toBe(0);
+    expect(result.stdout).toContain("bridge did not start within 15s");
+    expect(result.stdout).toContain("starting HTTP server");
+  });
 });
diff --git a/src/lib/domain/sandbox/logs.test.ts b/src/lib/domain/sandbox/logs.test.ts
index 16c38c28c02..f7f9f1aea4d 100644
--- a/src/lib/domain/sandbox/logs.test.ts
+++ b/src/lib/domain/sandbox/logs.test.ts
@@ -191,4 +191,39 @@ describe("mergeTailLogLines", () => {
   it("appends a trailing newline so callers can pipe through process.stdout.write", () => {
     expect(mergeTailLogLines(["[1] a"], 3).endsWith("\n")).toBe(true);
   });
+
+  it("preserves sparse-source content when a chatty source dominates by timestamp", () => {
+    const gatewayBoot = [
+      "[1779488800.000] [gateway] starting HTTP server",
+      "[1779488815.000] [telegram] [default] bridge did not start within 15s",
+    ].join("\n");
+    const openshellDense = Array.from(
+      { length: 200 },
+      (_v, i) => `[${1779488900 + i}.000] [sandbox] [INFO] log line ${i}`,
+    ).join("\n");
+    const merged = mergeTailLogLines([`${gatewayBoot}\n`, `${openshellDense}\n`], 200);
+    expect(merged).toContain("bridge did not start within 15s");
+    expect(merged).toContain("starting HTTP server");
+  });
+
+  it("inherits a preceding timestamp for an untimestamped diagnostic line in the same source", () => {
+    const gateway = [
+      "[1779488800.000] [gateway] starting provider",
+      "[telegram] [default] bridge did not start within 15s",
+    ].join("\n");
+    const openshellLater = Array.from(
+      { length: 50 },
+      (_v, i) => `[${1779489000 + i}.000] [sandbox] [INFO] line ${i}`,
+    ).join("\n");
+    const merged = mergeTailLogLines([`${gateway}\n`, `${openshellLater}\n`], 50);
+    expect(merged).toContain("bridge did not start within 15s");
+  });
+
+  it("caps the total output at maxLines with two chatty sources", () => {
+    const gateway = Array.from({ length: 500 }, (_v, i) => `[${1000 + i}.000] g${i}`).join("\n");
+    const openshell = Array.from({ length: 500 }, (_v, i) => `[${2000 + i}.000] o${i}`).join("\n");
+    const merged = mergeTailLogLines([`${gateway}\n`, `${openshell}\n`], 100);
+    const lines = merged.split("\n").filter((line) => line.length > 0);
+    expect(lines.length).toBeLessThanOrEqual(100);
+  });
 });
diff --git a/src/lib/domain/sandbox/logs.ts b/src/lib/domain/sandbox/logs.ts
index 5850cc32e4b..2472be373f5 100644
--- a/src/lib/domain/sandbox/logs.ts
+++ b/src/lib/domain/sandbox/logs.ts
@@ -132,22 +132,36 @@ interface ScoredLine {
 
 /**
  * Merge log lines from multiple sources into a single chronologically
- * ordered stream and return the last maxLines lines as a single
- * string. Lines without their own timestamp inherit the timestamp of
- * the previous line from the same source so multi-line log entries
- * stay attached to their header. Sort is stable on
- * (timestamp, sourceIndex, lineIndex) so identically-timestamped
- * lines from different sources interleave deterministically.
+ * ordered stream and return at most maxLines lines as a single string.
+ * Lines without their own timestamp inherit the timestamp of the
+ * previous line from the same source so multi-line log entries stay
+ * attached to their header. Sort is stable on (timestamp, sourceIndex,
+ * lineIndex) so identically-timestamped lines from different sources
+ * interleave deterministically.
+ *
+ * Each non-empty source is given a floor of floor(maxLines /
+ * non-empty-source-count) of its most recent lines so a sparse source
+ * is not silently squeezed out by a chatty source whose newer
+ * timestamps would otherwise dominate the global tail. Remaining slots
+ * up to maxLines are filled with the most recent remaining lines
+ * across all sources, ranked by timestamp. The final selection is
+ * returned in chronological order.
  *
  * When maxLines is non-positive, all merged lines are returned.
  */
 export function mergeTailLogLines(sources: ReadonlyArray<string>, maxLines: number): string {
-  const scored: ScoredLine[] = [];
+  const perSource: ScoredLine[][] = [];
+  let nonEmptyCount = 0;
   for (let sourceIndex = 0; sourceIndex < sources.length; sourceIndex += 1) {
     const raw = sources[sourceIndex] ?? "";
-    if (!raw) continue;
+    if (!raw) {
+      perSource.push([]);
+      continue;
+    }
+    nonEmptyCount += 1;
     const lines = raw.split(LINE_SPLIT_RE);
     if (lines.length > 0 && lines[lines.length - 1] === "") lines.pop();
+    const scored: ScoredLine[] = [];
     let lastSeen: number | null = null;
     for (let lineIndex = 0; lineIndex < lines.length; lineIndex += 1) {
       const text = lines[lineIndex];
@@ -160,15 +174,47 @@ export function mergeTailLogLines(sources: ReadonlyArray<string>, maxLines: numb
         lineIndex,
       });
     }
+    perSource.push(scored);
+  }
+
+  if (maxLines <= 0) {
+    const all = perSource.flat();
+    sortChronologically(all);
+    if (all.length === 0) return "";
+    return all.map((entry) => entry.text).join(NEWLINE) + NEWLINE;
+  }
+
+  const reserved = new Set<ScoredLine>();
+  const reservePerSource = nonEmptyCount > 0 ? Math.floor(maxLines / nonEmptyCount) : 0;
+  if (reservePerSource > 0) {
+    for (const scored of perSource) {
+      if (scored.length === 0) continue;
+      const tail = scored.slice(-reservePerSource);
+      for (const entry of tail) reserved.add(entry);
+    }
+  }
+
+  const remaining = maxLines - reserved.size;
+  if (remaining > 0) {
+    const candidates = perSource.flat().filter((entry) => !reserved.has(entry));
+    candidates.sort((a, b) => {
+      if (a.timestamp !== b.timestamp) return b.timestamp - a.timestamp;
+      if (a.sourceIndex !== b.sourceIndex) return a.sourceIndex - b.sourceIndex;
+      return b.lineIndex - a.lineIndex;
+    });
+    for (const entry of candidates.slice(0, remaining)) reserved.add(entry);
   }
 
-  scored.sort((a, b) => {
+  const final = Array.from(reserved);
+  sortChronologically(final);
+  if (final.length === 0) return "";
+  return final.map((entry) => entry.text).join(NEWLINE) + NEWLINE;
+}
+
+function sortChronologically(entries: ScoredLine[]): void {
+  entries.sort((a, b) => {
     if (a.timestamp !== b.timestamp) return a.timestamp - b.timestamp;
     if (a.sourceIndex !== b.sourceIndex) return a.sourceIndex - b.sourceIndex;
     return a.lineIndex - b.lineIndex;
   });
-
-  const tail = maxLines > 0 ? scored.slice(-maxLines) : scored;
-  if (tail.length === 0) return "";
-  return tail.map((entry) => entry.text).join(NEWLINE) + NEWLINE;
 }