feat(hooks): add task-reminder hook for task tool usage tracking

Injects a reminder after 10 tool turns without task tool usage. Tracks
per-session counters and cleans up on session deletion.

🤖 Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/hooks/task-reminder/hook.ts

@@ -0,0 +1,59 @@
+import type { PluginInput } from "@opencode-ai/plugin"
+
+const TASK_TOOLS = new Set([
+  "task",
+  "task_create",
+  "task_list",
+  "task_get",
+  "task_update",
+  "task_delete",
+])
+const TURN_THRESHOLD = 10
+const REMINDER_MESSAGE = `
+
+The task tools haven't been used recently. If you're tracking work, use task with action=create/update (or task_create/task_update) to record progress.`
+
+interface ToolExecuteInput {
+  tool: string
+  sessionID: string
+  callID: string
+}
+
+interface ToolExecuteOutput {
+  output: string
+}
+
+export function createTaskReminderHook(_ctx: PluginInput) {
+  const sessionCounters = new Map<string, number>()
+
+  const toolExecuteAfter = async (input: ToolExecuteInput, output: ToolExecuteOutput) => {
+    const { tool, sessionID } = input
+    const toolLower = tool.toLowerCase()
+
+    if (TASK_TOOLS.has(toolLower)) {
+      sessionCounters.set(sessionID, 0)
+      return
+    }
+
+    const currentCount = sessionCounters.get(sessionID) ?? 0
+    const newCount = currentCount + 1
+
+    if (newCount >= TURN_THRESHOLD) {
+      output.output += REMINDER_MESSAGE
+      sessionCounters.set(sessionID, 0)
+    } else {
+      sessionCounters.set(sessionID, newCount)
+    }
+  }
+
+  return {
+    "tool.execute.after": toolExecuteAfter,
+    event: async ({ event }: { event: { type: string; properties?: unknown } }) => {
+      if (event.type !== "session.deleted") return
+      const props = event.properties as { info?: { id?: string } } | undefined
+      const sessionId = props?.info?.id
+      if (!sessionId) return
+      sessionCounters.delete(sessionId)
+    },
+  }
+}

src/hooks/task-reminder/index.test.ts

@@ -0,0 +1,150 @@
+import { describe, test, expect, beforeEach } from "bun:test"
+import { createTaskReminderHook } from "./index"
+import type { PluginInput } from "@opencode-ai/plugin"
+
+const mockCtx = {} as PluginInput
+
+describe("TaskReminderHook", () => {
+  let hook: ReturnType<typeof createTaskReminderHook>
+
+  beforeEach(() => {
+    hook = createTaskReminderHook(mockCtx)
+  })
+
+  test("does not inject reminder before 10 turns", async () => {
+    //#given
+    const sessionID = "test-session"
+    const output = { output: "Result" }
+
+    //#when
+    for (let i = 0; i < 9; i++) {
+      await hook["tool.execute.after"]?.(
+        { tool: "bash", sessionID, callID: `call-${i}` },
+        output
+      )
+    }
+
+    //#then
+    expect(output.output).not.toContain("task tools haven't been used")
+  })
+
+  test("injects reminder after 10 turns without task tool usage", async () => {
+    //#given
+    const sessionID = "test-session"
+    const output = { output: "Result" }
+
+    //#when
+    for (let i = 0; i < 10; i++) {
+      await hook["tool.execute.after"]?.(
+        { tool: "bash", sessionID, callID: `call-${i}` },
+        output
+      )
+    }
+
+    //#then
+    expect(output.output).toContain("task tools haven't been used")
+  })
+
+  test("resets counter when task tool is used", async () => {
+    //#given
+    const sessionID = "test-session"
+    const output = { output: "Result" }
+
+    //#when
+    for (let i = 0; i < 5; i++) {
+      await hook["tool.execute.after"]?.(
+        { tool: "bash", sessionID, callID: `call-${i}` },
+        output
+      )
+    }
+    await hook["tool.execute.after"]?.(
+      { tool: "task", sessionID, callID: "call-task" },
+      output
+    )
+    for (let i = 0; i < 9; i++) {
+      await hook["tool.execute.after"]?.(
+        { tool: "bash", sessionID, callID: `call-after-${i}` },
+        output
+      )
+    }
+
+    //#then
+    expect(output.output).not.toContain("task tools haven't been used")
+  })
+
+  test("resets counter after injecting reminder", async () => {
+    //#given
+    const sessionID = "test-session"
+    const output1 = { output: "Result 1" }
+    const output2 = { output: "Result 2" }
+
+    //#when
+    for (let i = 0; i < 10; i++) {
+      await hook["tool.execute.after"]?.(
+        { tool: "bash", sessionID, callID: `call-1-${i}` },
+        output1
+      )
+    }
+    for (let i = 0; i < 9; i++) {
+      await hook["tool.execute.after"]?.(
+        { tool: "bash", sessionID, callID: `call-2-${i}` },
+        output2
+      )
+    }
+
+    //#then
+    expect(output1.output).toContain("task tools haven't been used")
+    expect(output2.output).not.toContain("task tools haven't been used")
+  })
+
+  test("tracks separate counters per session", async () => {
+    //#given
+    const session1 = "session-1"
+    const session2 = "session-2"
+    const output1 = { output: "Result 1" }
+    const output2 = { output: "Result 2" }
+
+    //#when
+    for (let i = 0; i < 10; i++) {
+      await hook["tool.execute.after"]?.(
+        { tool: "bash", sessionID: session1, callID: `call-${i}` },
+        output1
+      )
+    }
+    for (let i = 0; i < 5; i++) {
+      await hook["tool.execute.after"]?.(
+        { tool: "bash", sessionID: session2, callID: `call-${i}` },
+        output2
+      )
+    }
+
+    //#then
+    expect(output1.output).toContain("task tools haven't been used")
+    expect(output2.output).not.toContain("task tools haven't been used")
+  })
+
+  test("cleans up counters on session.deleted", async () => {
+    //#given
+    const sessionID = "test-session"
+    const output = { output: "Result" }
+
+    //#when
+    for (let i = 0; i < 10; i++) {
+      await hook["tool.execute.after"]?.(
+        { tool: "bash", sessionID, callID: `call-${i}` },
+        output
+      )
+    }
+    await hook.event?.({ event: { type: "session.deleted", properties: { info: { id: sessionID } } } })
+    const outputAfterDelete = { output: "Result" }
+    for (let i = 0; i < 9; i++) {
+      await hook["tool.execute.after"]?.(
+        { tool: "bash", sessionID, callID: `call-after-${i}` },
+        outputAfterDelete
+      )
+    }
+
+    //#then
+    expect(outputAfterDelete.output).not.toContain("task tools haven't been used")
+  })
+})

src/hooks/task-reminder/index.ts

@@ -0,0 +1 @@
+export { createTaskReminderHook } from "./hook";