refactor(background-agent): split manager.ts into focused modules

Extract 30+ single-responsibility modules from manager.ts (1556 LOC):
- task lifecycle: task-starter, task-completer, task-canceller, task-resumer
- task queries: task-queries, task-poller, task-queue-processor
- notifications: notification-builder, notification-tracker, parent-session-notifier
- session handling: session-validator, session-output-validator, session-todo-checker
- spawner: spawner/ directory with focused spawn modules
- utilities: duration-formatter, error-classifier, message-storage-locator
- result handling: result-handler-context, background-task-completer
- shutdown: background-manager-shutdown, process-signal

src/features/background-agent/session-output-validator.ts

@@ -0,0 +1,88 @@
+import type { OpencodeClient } from "./constants"
+import { log } from "../../shared"
+
+type SessionMessagePart = {
+  type?: string
+  text?: string
+  content?: unknown
+}
+
+function isObject(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null
+}
+
+function getMessageRole(message: unknown): string | undefined {
+  if (!isObject(message)) return undefined
+  const info = message["info"]
+  if (!isObject(info)) return undefined
+  const role = info["role"]
+  return typeof role === "string" ? role : undefined
+}
+
+function getMessageParts(message: unknown): SessionMessagePart[] {
+  if (!isObject(message)) return []
+  const parts = message["parts"]
+  if (!Array.isArray(parts)) return []
+
+  return parts
+    .filter((part): part is SessionMessagePart => isObject(part))
+    .map((part) => ({
+      type: typeof part["type"] === "string" ? part["type"] : undefined,
+      text: typeof part["text"] === "string" ? part["text"] : undefined,
+      content: part["content"],
+    }))
+}
+
+function partHasContent(part: SessionMessagePart): boolean {
+  if (part.type === "text" || part.type === "reasoning") {
+    return Boolean(part.text && part.text.trim().length > 0)
+  }
+  if (part.type === "tool") return true
+  if (part.type === "tool_result") {
+    if (typeof part.content === "string") return part.content.trim().length > 0
+    if (Array.isArray(part.content)) return part.content.length > 0
+    return Boolean(part.content)
+  }
+  return false
+}
+
+export async function validateSessionHasOutput(
+  client: OpencodeClient,
+  sessionID: string
+): Promise<boolean> {
+  try {
+    const response = await client.session.messages({
+      path: { id: sessionID },
+    })
+
+    const messagesRaw = "data" in response ? response.data : []
+    const messages = Array.isArray(messagesRaw) ? messagesRaw : []
+
+    const hasAssistantOrToolMessage = messages.some((message) => {
+      const role = getMessageRole(message)
+      return role === "assistant" || role === "tool"
+    })
+
+    if (!hasAssistantOrToolMessage) {
+      log("[background-agent] No assistant/tool messages found in session:", sessionID)
+      return false
+    }
+
+    const hasContent = messages.some((message) => {
+      const role = getMessageRole(message)
+      if (role !== "assistant" && role !== "tool") return false
+      const parts = getMessageParts(message)
+      return parts.some(partHasContent)
+    })
+
+    if (!hasContent) {
+      log("[background-agent] Messages exist but no content found in session:", sessionID)
+      return false
+    }
+
+    return true
+  } catch (error) {
+    log("[background-agent] Error validating session output:", error)
+    return true
+  }
+}