feat(background-agent): add parentAgent tracking to preserve agent context in background tasks

- Add parentAgent field to BackgroundTask, LaunchInput, and ResumeInput interfaces
- Pass parentAgent through background task manager to preserve agent identity
- Update sisyphus-orchestrator to set orchestrator-sisyphus agent context
- Add session tracking for background agents to prevent context loss
- Propagate agent context in background-task and sisyphus-task tools

This ensures background/subagent spawned tasks maintain proper agent context for notifications and continuity.

🤖 Generated with assistance of oh-my-opencode

src/features/background-agent/manager.ts

@@ -98,6 +98,7 @@ export class BackgroundManager {
         lastUpdate: new Date(),
       },
       parentModel: input.parentModel,
+      parentAgent: input.parentAgent,
       model: input.model,
       concurrencyKey,
     }
@@ -236,6 +237,7 @@ export class BackgroundManager {
     existingTask.parentSessionID = input.parentSessionID
     existingTask.parentMessageID = input.parentMessageID
     existingTask.parentModel = input.parentModel
+    existingTask.parentAgent = input.parentAgent
 
     existingTask.progress = {
       toolCalls: existingTask.progress?.toolCalls ?? 0,
@@ -438,8 +440,8 @@ export class BackgroundManager {
       }
 
       try {
-        // Use only parentModel - don't fallback to prevMessage.model
+        // Use only parentModel/parentAgent - don't fallback to prevMessage
-        // This prevents accidentally changing parent session's model
+        // This prevents accidentally changing parent session's model/agent
         const modelField = task.parentModel?.providerID && task.parentModel?.modelID
           ? { providerID: task.parentModel.providerID, modelID: task.parentModel.modelID }
           : undefined
@@ -447,6 +449,7 @@ export class BackgroundManager {
         await this.client.session.prompt({
           path: { id: task.parentSessionID },
           body: {
+            agent: task.parentAgent,
             model: modelField,
             parts: [{ type: "text", text: message }],
           },

src/features/background-agent/types.ts

@@ -30,6 +30,8 @@ export interface BackgroundTask {
   model?: { providerID: string; modelID: string }
   /** Agent name used for concurrency tracking */
   concurrencyKey?: string
+  /** Parent session's agent name for notification */
+  parentAgent?: string
 }
 
 export interface LaunchInput {
@@ -39,6 +41,7 @@ export interface LaunchInput {
   parentSessionID: string
   parentMessageID: string
   parentModel?: { providerID: string; modelID: string }
+  parentAgent?: string
   model?: { providerID: string; modelID: string }
   skills?: string[]
   skillContent?: string
@@ -50,4 +53,5 @@ export interface ResumeInput {
   parentSessionID: string
   parentMessageID: string
   parentModel?: { providerID: string; modelID: string }
+  parentAgent?: string
 }

src/hooks/sisyphus-orchestrator/index.ts

@@ -352,6 +352,7 @@ export function createSisyphusOrchestratorHook(
       await ctx.client.session.prompt({
         path: { id: sessionID },
         body: {
+          agent: "orchestrator-sisyphus",
           parts: [{ type: "text", text: prompt }],
         },
         query: { directory: ctx.directory },

src/tools/background-task/tools.ts

@@ -74,6 +74,7 @@ export function createBackgroundTask(manager: BackgroundManager): ToolDefinition
           parentSessionID: ctx.sessionID,
           parentMessageID: ctx.messageID,
           parentModel,
+          parentAgent: prevMessage?.agent,
         })
 
         ctx.metadata?.({

src/tools/sisyphus-task/tools.ts

@@ -9,6 +9,7 @@ import { findNearestMessageWithFields, MESSAGE_STORAGE } from "../../features/ho
 import { resolveMultipleSkills } from "../../features/opencode-skill-loader/skill-content"
 import { createBuiltinSkills } from "../../features/builtin-skills/skills"
 import { getTaskToastManager } from "../../features/task-toast-manager"
+import { subagentSessions } from "../../features/claude-code-session-state"
 
 type OpencodeClient = PluginInput["client"]
 
@@ -159,6 +160,7 @@ export function createSisyphusTask(options: SisyphusTaskToolOptions): ToolDefini
               parentSessionID: ctx.sessionID,
               parentMessageID: ctx.messageID,
               parentModel,
+              parentAgent: prevMessage?.agent,
             })
 
             ctx.metadata?.({
@@ -325,6 +327,7 @@ ${textContent || "(No text output)"}`
             parentSessionID: ctx.sessionID,
             parentMessageID: ctx.messageID,
             parentModel,
+            parentAgent: prevMessage?.agent,
             model: categoryModel,
             skills: args.skills,
             skillContent: systemContent,
@@ -352,6 +355,7 @@ System notifies on completion. Use \`background_output\` with task_id="${task.id
 
       const toastManager = getTaskToastManager()
       let taskId: string | undefined
+      let syncSessionID: string | undefined
 
       try {
         const createResult = await client.session.create({
@@ -366,6 +370,8 @@ System notifies on completion. Use \`background_output\` with task_id="${task.id
         }
 
         const sessionID = createResult.data.id
+        syncSessionID = sessionID
+        subagentSessions.add(sessionID)
         taskId = `sync_${sessionID.slice(0, 8)}`
         const startTime = new Date()
 
@@ -461,6 +467,8 @@ System notifies on completion. Use \`background_output\` with task_id="${task.id
           toastManager.removeTask(taskId)
         }
 
+        subagentSessions.delete(sessionID)
+
         return `Task completed in ${duration}.
 
 Agent: ${agentToUse}${args.category ? ` (category: ${args.category})` : ""}
@@ -473,6 +481,9 @@ ${textContent || "(No text output)"}`
         if (toastManager && taskId !== undefined) {
           toastManager.removeTask(taskId)
         }
+        if (syncSessionID) {
+          subagentSessions.delete(syncSessionID)
+        }
         const message = error instanceof Error ? error.message : String(error)
         return `❌ Task failed: ${message}`
       }