oh-my-opencode/src/tools/background-task/modules/background-cancel.ts

import { tool, type ToolDefinition } from "@opencode-ai/plugin"
import type { BackgroundCancelClient } from "../types"
import type { BackgroundManager } from "../../../features/background-agent"
import type { BackgroundCancelArgs } from "../types"
import { BACKGROUND_CANCEL_DESCRIPTION } from "../constants"

export function createBackgroundCancel(manager: BackgroundManager, client: BackgroundCancelClient): ToolDefinition {
  return tool({
    description: BACKGROUND_CANCEL_DESCRIPTION,
    args: {
      taskId: tool.schema.string().optional().describe("Task ID to cancel (required if all=false)"),
      all: tool.schema.boolean().optional().describe("Cancel all running background tasks (default: false)"),
    },
    async execute(args: BackgroundCancelArgs, toolContext) {
      try {
        const cancelAll = args.all === true

        if (!cancelAll && !args.taskId) {
          return `[ERROR] Invalid arguments: Either provide a taskId or set all=true to cancel all running tasks.`
        }

        if (cancelAll) {
          const tasks = manager.getAllDescendantTasks(toolContext.sessionID)
          const cancellableTasks = tasks.filter((t: any) => t.status === "running" || t.status === "pending")

          if (cancellableTasks.length === 0) {
            return `No running or pending background tasks to cancel.`
          }

          const cancelledInfo: Array<{
            id: string
            description: string
            status: string
            sessionID?: string
          }> = []

          for (const task of cancellableTasks) {
            const originalStatus = task.status
            const cancelled = await manager.cancelTask(task.id, {
              source: "background_cancel",
              abortSession: originalStatus === "running",
              skipNotification: true,
            })
            if (!cancelled) continue
            cancelledInfo.push({
              id: task.id,
              description: task.description,
              status: originalStatus === "pending" ? "pending" : "running",
              sessionID: task.sessionID,
            })
          }

          const tableRows = cancelledInfo
            .map(t => `| \`${t.id}\` | ${t.description} | ${t.status} | ${t.sessionID ? `\`${t.sessionID}\`` : "(not started)"} |`)
            .join("\n")

           const resumableTasks = cancelledInfo.filter(t => t.sessionID)
           const resumeSection = resumableTasks.length > 0
             ? `\n## Continue Instructions

To continue a cancelled task, use:
\`\`\`
task(session_id="<session_id>", prompt="Continue: <your follow-up>")
\`\`\`

Continuable sessions:
${resumableTasks.map(t => `- \`${t.sessionID}\` (${t.description})`).join("\n")}`
             : ""

          return `Cancelled ${cancelledInfo.length} background task(s):

| Task ID | Description | Status | Session ID |
|---------|-------------|--------|------------|
${tableRows}
${resumeSection}`
        }

        const task = manager.getTask(args.taskId!)
        if (!task) {
          return `[ERROR] Task not found: ${args.taskId}`
        }

        if (task.status !== "running" && task.status !== "pending") {
          return `[ERROR] Cannot cancel task: current status is "${task.status}".
Only running or pending tasks can be cancelled.`
        }

        const cancelled = await manager.cancelTask(task.id, {
          source: "background_cancel",
          abortSession: task.status === "running",
          skipNotification: true,
        })
        if (!cancelled) {
          return `[ERROR] Failed to cancel task: ${task.id}`
        }

        if (task.status === "pending") {
          return `Pending task cancelled successfully

Task ID: ${task.id}
Description: ${task.description}
Status: ${task.status}`
        }

        return `Task cancelled successfully

Task ID: ${task.id}
Description: ${task.description}
Session ID: ${task.sessionID}
Status: ${task.status}`
      } catch (error) {
        return `[ERROR] Error cancelling task: ${error instanceof Error ? error.message : String(error)}`
      }
    },
  })
}