fix: address 5 edge cases from review-work findings

- C3: include command args in auto-slash-command dedup key
- H2: track completed task summaries for ALL COMPLETE message
- H9: increment tmux close retry count on re-mark
- H8: detect stale MCP connections after disconnect+reconnect race
- H8: guard disconnectedSessions growth for non-MCP sessions
- C1: await tmux cleanup in plugin dispose lifecycle

src/features/background-agent/manager.ts

@@ -121,6 +121,7 @@ export class BackgroundManager {
   private queuesByKey: Map<string, QueueItem[]> = new Map()
   private processingKeys: Set<string> = new Set()
   private completionTimers: Map<string, ReturnType<typeof setTimeout>> = new Map()
+  private completedTaskSummaries: Map<string, Array<{id: string, description: string}>> = new Map()
   private idleDeferralTimers: Map<string, ReturnType<typeof setTimeout>> = new Map()
   private notificationQueueByParent: Map<string, Promise<void>> = new Map()
   private rootDescendantCounts: Map<string, number>
@@ -1379,6 +1380,14 @@ export class BackgroundManager {
       })
     }
 
+    if (!this.completedTaskSummaries.has(task.parentSessionID)) {
+      this.completedTaskSummaries.set(task.parentSessionID, [])
+    }
+    this.completedTaskSummaries.get(task.parentSessionID)!.push({
+      id: task.id,
+      description: task.description,
+    })
+
     // Update pending tracking and check if all tasks complete
     const pendingSet = this.pendingByParent.get(task.parentSessionID)
     let allComplete = false
@@ -1398,10 +1407,13 @@ export class BackgroundManager {
     }
 
     const completedTasks = allComplete
-      ? Array.from(this.tasks.values())
-        .filter(t => t.parentSessionID === task.parentSessionID && t.status !== "running" && t.status !== "pending")
+      ? (this.completedTaskSummaries.get(task.parentSessionID) ?? [{ id: task.id, description: task.description }])
       : []
 
+    if (allComplete) {
+      this.completedTaskSummaries.delete(task.parentSessionID)
+    }
+
     const statusText = task.status === "completed"
       ? "COMPLETED"
       : task.status === "interrupt"
@@ -1740,6 +1752,7 @@ Use \`background_output(task_id="${task.id}")\` to retrieve this result when rea
     this.queuesByKey.clear()
     this.processingKeys.clear()
     this.taskHistory.clearAll()
+    this.completedTaskSummaries.clear()
     this.unregisterProcessCleanup()
     log("[background-agent] Shutdown complete")
 

src/features/skill-mcp-manager/cleanup.ts

@@ -87,7 +87,16 @@ async function cleanupIdleClients(state: SkillMcpManagerState): Promise<void> {
 }
 
 export async function disconnectSession(state: SkillMcpManagerState, sessionID: string): Promise<void> {
-  state.disconnectedSessions.add(sessionID)
+  let hasPendingForSession = false
+  for (const key of state.pendingConnections.keys()) {
+    if (key.startsWith(`${sessionID}:`)) {
+      hasPendingForSession = true
+      break
+    }
+  }
+  if (hasPendingForSession) {
+    state.disconnectedSessions.add(sessionID)
+  }
   const keysToRemove: string[] = []
 
   for (const [key, managed] of state.clients.entries()) {

src/features/skill-mcp-manager/connection-race.test.ts

@@ -154,11 +154,11 @@ describe("getOrCreateClient disconnect race", () => {
     expect(createdClients[0]?.close).not.toHaveBeenCalled()
   })
 
-  it("#given no pending connections #when disconnectSession is called #then no errors occur and the session is added to disconnectedSessions", async () => {
+  it("#given no pending connections #when disconnectSession is called #then no errors occur and session is not added to disconnectedSessions", async () => {
     const state = createState()
 
     await expect(disconnectSession(state, "session-a")).resolves.toBeUndefined()
-    expect(state.disconnectedSessions.has("session-a")).toBe(true)
+    expect(state.disconnectedSessions.has("session-a")).toBe(false)
     expect(state.pendingConnections.size).toBe(0)
     expect(state.clients.size).toBe(0)
   })

src/features/skill-mcp-manager/connection.ts

@@ -29,9 +29,16 @@ export async function getOrCreateClient(params: {
   }
 
   const expandedConfig = expandEnvVarsInObject(config)
-  const connectionPromise = (async () => {
+  let currentConnectionPromise!: Promise<Client>
+  currentConnectionPromise = (async () => {
     const client = await createClient({ state, clientKey, info, config: expandedConfig })
 
+    const isStale = state.pendingConnections.has(clientKey) && state.pendingConnections.get(clientKey) !== currentConnectionPromise
+    if (isStale) {
+      try { await client.close() } catch {}
+      throw new Error(`Connection for "${info.sessionID}" was superseded by a newer connection attempt.`)
+    }
+
     if (state.disconnectedSessions.has(info.sessionID)) {
       await forceReconnect(state, clientKey)
       throw new Error(`Session "${info.sessionID}" disconnected during MCP connection setup.`)
@@ -40,13 +47,13 @@ export async function getOrCreateClient(params: {
     return client
   })()
 
-  state.pendingConnections.set(clientKey, connectionPromise)
+  state.pendingConnections.set(clientKey, currentConnectionPromise)
 
   try {
-    const client = await connectionPromise
+    const client = await currentConnectionPromise
     return client
   } finally {
-    if (state.pendingConnections.get(clientKey) === connectionPromise) {
+    if (state.pendingConnections.get(clientKey) === currentConnectionPromise) {
       state.pendingConnections.delete(clientKey)
     }
   }

src/features/tmux-subagent/tracked-session-state.ts

@@ -23,5 +23,6 @@ export function markTrackedSessionClosePending(tracked: TrackedSession): Tracked
   return {
     ...tracked,
     closePending: true,
+    closeRetryCount: tracked.closePending ? tracked.closeRetryCount + 1 : tracked.closeRetryCount,
   }
 }