fix(todo-continuation-enforcer): add stagnation guard helper

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/hooks/todo-continuation-enforcer/stagnation-detection.ts

@@ -0,0 +1,33 @@
+import { log } from "../../shared/logger"
+
+import { HOOK_NAME, MAX_STAGNATION_COUNT } from "./constants"
+import type { ContinuationProgressUpdate } from "./session-state"
+
+export function shouldStopForStagnation(args: {
+  sessionID: string
+  incompleteCount: number
+  progressUpdate: ContinuationProgressUpdate
+}): boolean {
+  const { sessionID, incompleteCount, progressUpdate } = args
+
+  if (progressUpdate.hasProgressed) {
+    log(`[${HOOK_NAME}] Progress detected: reset stagnation count`, {
+      sessionID,
+      previousIncompleteCount: progressUpdate.previousIncompleteCount,
+      incompleteCount,
+    })
+  }
+
+  if (progressUpdate.stagnationCount < MAX_STAGNATION_COUNT) {
+    return false
+  }
+
+  log(`[${HOOK_NAME}] Skipped: todo continuation stagnated`, {
+    sessionID,
+    incompleteCount,
+    previousIncompleteCount: progressUpdate.previousIncompleteCount,
+    stagnationCount: progressUpdate.stagnationCount,
+    maxStagnationCount: MAX_STAGNATION_COUNT,
+  })
+  return true
+}