fix(hooks): improve TODO continuation race condition handling with state machine pattern

- Replace multiple Set-based tracking with explicit SessionStatus state machine
- Implement setTimeout+clearTimeout pattern for robust race condition handling
- SessionStatus tracks: idle → continuation-sent or aborted states
- Increase grace period to 500ms to accommodate event ordering delays
- Add cleanupSession utility for proper resource cleanup

This addresses ESC abort not canceling continuation prompts when session.idle
arrives before session.error event, which can occur due to async event processing
in OpenCode plugin system

src/hooks/todo-continuation-enforcer.ts

@@ -7,6 +7,8 @@ interface Todo {
   id: string
 }
 
+type SessionStatus = "idle" | "aborted" | "continuation-sent"
+
 const CONTINUATION_PROMPT = `[SYSTEM REMINDER - TODO CONTINUATION]
 
 Incomplete tasks remain in your todo list. Continue working on the next pending task.
@@ -15,6 +17,8 @@ Incomplete tasks remain in your todo list. Continue working on the next pending
 - Mark each task complete when finished
 - Do not stop until all tasks are done`
 
+const CONTINUATION_DELAY_MS = 500
+
 function detectInterrupt(error: unknown): boolean {
   if (!error) return false
   if (typeof error === "object") {
@@ -33,43 +37,36 @@ function detectInterrupt(error: unknown): boolean {
 }
 
 export function createTodoContinuationEnforcer(ctx: PluginInput) {
-  const remindedSessions = new Set<string>()
-  const interruptedSessions = new Set<string>()
-  const errorSessions = new Set<string>()
+  const sessionStates = new Map<string, SessionStatus>()
+  const pendingContinuations = new Map<string, Timer>()
 
-  return async ({ event }: { event: { type: string; properties?: unknown } }) => {
-    const props = event.properties as Record<string, unknown> | undefined
+  const cleanupSession = (sessionID: string) => {
+    const timer = pendingContinuations.get(sessionID)
+    if (timer) clearTimeout(timer)
+    pendingContinuations.delete(sessionID)
+    sessionStates.delete(sessionID)
+  }
 
-    if (event.type === "session.error") {
-      const sessionID = props?.sessionID as string | undefined
-      if (sessionID) {
-        errorSessions.add(sessionID)
-        if (detectInterrupt(props?.error)) {
-          interruptedSessions.add(sessionID)
-        }
-      }
-      return
+  const cancelPendingContinuation = (sessionID: string) => {
+    const timer = pendingContinuations.get(sessionID)
+    if (timer) {
+      clearTimeout(timer)
+      pendingContinuations.delete(sessionID)
     }
+    sessionStates.set(sessionID, "aborted")
+  }
 
-    if (event.type === "session.idle") {
-      const sessionID = props?.sessionID as string | undefined
-      if (!sessionID) return
+  const scheduleContinuation = (sessionID: string) => {
+    const prev = pendingContinuations.get(sessionID)
+    if (prev) clearTimeout(prev)
 
-      // Wait for potential session.error events to be processed first
-      await new Promise(resolve => setTimeout(resolve, 150))
+    sessionStates.set(sessionID, "idle")
 
-      const shouldBypass = interruptedSessions.has(sessionID) || errorSessions.has(sessionID)
+    const timer = setTimeout(async () => {
+      pendingContinuations.delete(sessionID)
 
-      interruptedSessions.delete(sessionID)
-      errorSessions.delete(sessionID)
-
-      if (shouldBypass) {
-        return
-      }
-
-      if (remindedSessions.has(sessionID)) {
-        return
-      }
+      const state = sessionStates.get(sessionID)
+      if (state !== "idle") return
 
       let todos: Todo[] = []
       try {
@@ -93,13 +90,7 @@ export function createTodoContinuationEnforcer(ctx: PluginInput) {
         return
       }
 
-      remindedSessions.add(sessionID)
-
-      // Re-check if abort occurred during the delay
-      if (interruptedSessions.has(sessionID) || errorSessions.has(sessionID)) {
-        remindedSessions.delete(sessionID)
-        return
-      }
+      sessionStates.set(sessionID, "continuation-sent")
 
       try {
         await ctx.client.session.prompt({
@@ -115,24 +106,46 @@ export function createTodoContinuationEnforcer(ctx: PluginInput) {
           query: { directory: ctx.directory },
         })
       } catch {
-        remindedSessions.delete(sessionID)
+        sessionStates.delete(sessionID)
       }
+    }, CONTINUATION_DELAY_MS)
+
+    pendingContinuations.set(sessionID, timer)
+  }
+
+  return async ({ event }: { event: { type: string; properties?: unknown } }) => {
+    const props = event.properties as Record<string, unknown> | undefined
+
+    if (event.type === "session.error") {
+      const sessionID = props?.sessionID as string | undefined
+      if (sessionID && detectInterrupt(props?.error)) {
+        cancelPendingContinuation(sessionID)
+      }
+      return
+    }
+
+    if (event.type === "session.idle") {
+      const sessionID = props?.sessionID as string | undefined
+      if (!sessionID) return
+
+      const state = sessionStates.get(sessionID)
+      if (state === "continuation-sent") return
+
+      scheduleContinuation(sessionID)
     }
 
     if (event.type === "message.updated") {
       const info = props?.info as Record<string, unknown> | undefined
       const sessionID = info?.sessionID as string | undefined
       if (sessionID && info?.role === "user") {
-        remindedSessions.delete(sessionID)
+        sessionStates.delete(sessionID)
       }
     }
 
     if (event.type === "session.deleted") {
       const sessionInfo = props?.info as { id?: string } | undefined
       if (sessionInfo?.id) {
-        remindedSessions.delete(sessionInfo.id)
-        interruptedSessions.delete(sessionInfo.id)
-        errorSessions.delete(sessionInfo.id)
+        cleanupSession(sessionInfo.id)
       }
     }
   }