Raise leaf no-progress repeat limit from 2 to 5

Two identical tool-call fingerprints hard-stopped a leaf worker on
legitimate polling (rerunning a flaky test, checking a build). The
director-level thrash threshold already sits at 5 for the same
forensic reason (CL-5611: a prior 4-repeat pause false-positived on
this exact pattern), so mirror it here instead of stopping at 2.

Fixes CL-6776
https://linear.app/abklabs/issue/CL-6776

Author: TheGreatAxios

src/subagent/index.test.ts

@@ -162,9 +162,41 @@ describe("sub-agent stop helpers", () => {
   });
 
   test("no-progress trips at the default repeat limit", () => {
-    expect(DEFAULT_SUBAGENT_REPEAT_LIMIT).toBe(2);
-    expect(subAgentNoProgress(1, DEFAULT_SUBAGENT_REPEAT_LIMIT)).toBe(false);
-    expect(subAgentNoProgress(2, DEFAULT_SUBAGENT_REPEAT_LIMIT)).toBe(true);
+    expect(DEFAULT_SUBAGENT_REPEAT_LIMIT).toBe(5);
+    expect(subAgentNoProgress(4, DEFAULT_SUBAGENT_REPEAT_LIMIT)).toBe(false);
+    expect(subAgentNoProgress(5, DEFAULT_SUBAGENT_REPEAT_LIMIT)).toBe(true);
+  });
+
+  test("legitimate polling (2-4 identical fingerprints) does not hard-stop (CL-6776)", () => {
+    // A worker rerunning `git status` or polling a build a few times while
+    // waiting must not be hard-blocked on identical re-dispatch.
+    for (const consecutive of [2, 3, 4]) {
+      expect(subAgentNoProgress(consecutive, DEFAULT_SUBAGENT_REPEAT_LIMIT)).toBe(false);
+      expect(
+        evaluateSubAgentStop({
+          hasToolCalls: true,
+          everHadToolCalls: true,
+          turnsCompleted: consecutive,
+          maxTurns: DEFAULT_SUBAGENT_MAX_TURNS,
+          consecutiveIdentical: consecutive,
+          repeatLimit: DEFAULT_SUBAGENT_REPEAT_LIMIT,
+        }),
+      ).toBeNull();
+    }
+  });
+
+  test("a true runaway (>5 identical fingerprints) still hard-stops", () => {
+    expect(subAgentNoProgress(6, DEFAULT_SUBAGENT_REPEAT_LIMIT)).toBe(true);
+    expect(
+      evaluateSubAgentStop({
+        hasToolCalls: true,
+        everHadToolCalls: true,
+        turnsCompleted: 6,
+        maxTurns: DEFAULT_SUBAGENT_MAX_TURNS,
+        consecutiveIdentical: 6,
+        repeatLimit: DEFAULT_SUBAGENT_REPEAT_LIMIT,
+      }),
+    ).toBe("no-progress");
   });
 
   test("fingerprint is null when a turn has no tool calls", () => {

src/subagent/stop-policy.ts

@@ -18,8 +18,14 @@ import {
   parseSubAgentReport,
 } from "./report.js";
 
-/** Consecutive identical tool-call fingerprints before a leaf is forced to stop. */
-export const DEFAULT_SUBAGENT_REPEAT_LIMIT = 2;
+// Consecutive identical tool-call fingerprints before a leaf is forced to
+// stop. Mirrors IDENTICAL_REPEAT_MIN below (the director-level period-1
+// thrash threshold): the same forensic scan found zero occurrences of even
+// two consecutive identical fingerprints in local trace history, and CL-5611
+// found the previous 4-repeat hard pause false-positived on legitimate
+// polling (rerunning a flaky test, polling a build) — hence a threshold set
+// above 4, not at 2.
+export const DEFAULT_SUBAGENT_REPEAT_LIMIT = 5;
 
 // Minimum gap kept between an opt-in internal deadline and the outer
 // tool-execution watchdog, so there is time left for the salvage report to