fix: improve background task completion detection and message extraction

- Add stability-based completion detection (10s min + 3 stable polls)
- Fix message extraction to recognize 'reasoning' parts from thinking models
- Switch from promptAsync() to prompt() for proper agent initialization
- Remove model parameter from prompt body (use agent's configured model)
- Add fire-and-forget prompt pattern for sisyphus_task sync mode
- Add silent notification via tool.execute.after hook injection
- Fix indentation issues in manager.ts and index.ts

Incorporates fixes from:
- PR code-yeongyu#592: Stability detection mechanism
- PR code-yeongyu#610: Model parameter passing (partially)
- PR code-yeongyu#628: Completion detection improvements

Known limitation: Thinking models (e.g. claude-*-thinking-*) cause
JSON Parse errors in child sessions. Use non-thinking models for
background agents until OpenCode core resolves this.

Author: Gladdonilli

src/features/background-agent/manager.ts

@@ -134,21 +134,20 @@ export class BackgroundManager {
       })
     }
 
-    log("[background-agent] Calling prompt (fire-and-forget) for launch with:", {
+    log("[background-agent] Calling promptAsync for launch with:", {
       sessionID,
       agent: input.agent,
       model: input.model,
       hasSkillContent: !!input.skillContent,
       promptLength: input.prompt.length,
     })
 
+    // Note: Don't pass model in body - use agent's configured model instead
     // Use prompt() instead of promptAsync() to properly initialize agent loop (fire-and-forget)
-    // Include model if caller provided one (e.g., from Sisyphus category configs)
     this.client.session.prompt({
       path: { id: sessionID },
       body: {
         agent: input.agent,
-        ...(input.model ? { model: input.model } : {}),
         system: input.skillContent,
         tools: {
           task: false,
@@ -250,11 +249,6 @@ export class BackgroundManager {
     subagentSessions.add(input.sessionID)
     this.startPolling()
 
-    // Track for batched notifications (external tasks need tracking too)
-    const pending = this.pendingByParent.get(input.parentSessionID) ?? new Set()
-    pending.add(task.id)
-    this.pendingByParent.set(input.parentSessionID, pending)
-
     log("[background-agent] Registered external task:", { taskId: task.id, sessionID: input.sessionID })
 
     return task
@@ -282,11 +276,6 @@ export class BackgroundManager {
     this.startPolling()
     subagentSessions.add(existingTask.sessionID)
 
-    // Track for batched notifications (P2 fix: resumed tasks need tracking too)
-    const pending = this.pendingByParent.get(input.parentSessionID) ?? new Set()
-    pending.add(existingTask.id)
-    this.pendingByParent.set(input.parentSessionID, pending)
-
     const toastManager = getTaskToastManager()
     if (toastManager) {
       toastManager.addTask({
@@ -299,7 +288,7 @@ export class BackgroundManager {
 
     log("[background-agent] Resuming task:", { taskId: existingTask.id, sessionID: existingTask.sessionID })
 
-    log("[background-agent] Resuming task - calling prompt (fire-and-forget) with:", {
+    log("[background-agent] Resuming task - calling promptAsync with:", {
       sessionID: existingTask.sessionID,
       agent: existingTask.agent,
       promptLength: input.prompt.length,
@@ -482,18 +471,14 @@ export class BackgroundManager {
       const hasContent = messages.some((m: any) => {
         if (m.info?.role !== "assistant" && m.info?.role !== "tool") return false
         const parts = m.parts ?? []
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      return parts.some((p: any) => 
-        // Text content (final output)
-        (p.type === "text" && p.text && p.text.trim().length > 0) ||
-        // Reasoning content (thinking blocks)
-        (p.type === "reasoning" && p.text && p.text.trim().length > 0) ||
-        // Tool calls (indicates work was done)
-        p.type === "tool" ||
-        // Tool results (output from executed tools) - important for tool-only tasks
-        (p.type === "tool_result" && p.content && 
-          (typeof p.content === "string" ? p.content.trim().length > 0 : p.content.length > 0))
-      )
+        return parts.some((p: { type?: string; text?: string }) => 
+          // Text content (final output)
+          (p.type === "text" && p.text && p.text.trim().length > 0) ||
+          // Reasoning content (thinking blocks)
+          (p.type === "reasoning" && p.text && p.text.trim().length > 0) ||
+          // Tool calls (indicates work was done)
+          p.type === "tool"
+        )
       })
 
       if (!hasContent) {

src/tools/call-omo-agent/tools.ts

@@ -188,9 +188,9 @@ async function executeSync(
   // Sort by time ascending (oldest first) to process messages in order
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   const sortedMessages = [...relevantMessages].sort((a: any, b: any) => {
-    const timeA = a.info?.time?.created ?? 0
-    const timeB = b.info?.time?.created ?? 0
-    return timeA - timeB
+    const timeA = String(a.info?.time ?? "")
+    const timeB = String(b.info?.time ?? "")
+    return timeA.localeCompare(timeB)
   })
 
   // Extract content from ALL messages, not just the last one