fix(todo-continuation-enforcer): tighten post-compaction guard with session-agent fallback

Refine continuation agent resolution to prefer session-state agent fallback while keeping compaction-specific protection. Replace sticky boolean compaction flag with a short-lived timestamp guard so unresolved agents are blocked only during the immediate post-compaction window, avoiding long-lived suppression and preserving existing continuation behavior.

src/hooks/todo-continuation-enforcer/continuation-injection.ts

@@ -1,6 +1,7 @@
 import type { PluginInput } from "@opencode-ai/plugin"
 
 import type { BackgroundManager } from "../../features/background-agent"
+import { getSessionAgent } from "../../features/claude-code-session-state"
 import {
   createInternalAgentTextPart,
   normalizeSDKResponse,
@@ -20,6 +21,7 @@ import {
   DEFAULT_SKIP_AGENTS,
   HOOK_NAME,
 } from "./constants"
+import { isCompactionGuardActive } from "./compaction-guard"
 import { getMessageDir } from "./message-directory"
 import { getIncompleteCount } from "./todo"
 import type { ResolvedMessageInfo, Todo } from "./types"
@@ -88,7 +90,7 @@ export async function injectContinuation(args: {
     return
   }
 
-  let agentName = resolvedInfo?.agent
+  let agentName = resolvedInfo?.agent ?? getSessionAgent(sessionID)
   let model = resolvedInfo?.model
   let tools = resolvedInfo?.tools
 
@@ -122,7 +124,7 @@ export async function injectContinuation(args: {
 
   if (!agentName) {
     const compactionState = sessionStateStore.getExistingState(sessionID)
-    if (compactionState?.hasRecentCompaction) {
+    if (compactionState && isCompactionGuardActive(compactionState, Date.now())) {
       log(`[${HOOK_NAME}] Skipped: agent unknown after compaction`, { sessionID })
       return
     }