feat: add toast notifications for task execution

- Display toast when background task starts in BackgroundManager
- Display toast when sisyphus_task sync task starts
- Wire up prometheus-md-only hook initialization in main plugin

This provides user feedback in OpenCode TUI where task TUI is not visible.

🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/features/background-agent/manager.ts

@@ -122,6 +122,19 @@ export class BackgroundManager {
 
     log("[background-agent] Launching task:", { taskId: task.id, sessionID, agent: input.agent })
 
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    const tuiClient = this.client as any
+    if (tuiClient.tui?.showToast) {
+      tuiClient.tui.showToast({
+        body: {
+          title: "Background Task Started",
+          message: `"${input.description}" running with ${input.agent}`,
+          variant: "info",
+          duration: 3000,
+        },
+      }).catch(() => {})
+    }
+
     this.client.session.promptAsync({
       path: { id: sessionID },
       body: {

src/index.ts

@@ -29,6 +29,7 @@ import {
   createTaskResumeInfoHook,
   createStartWorkHook,
   createSisyphusOrchestratorHook,
+  createPrometheusMdOnlyHook,
 } from "./hooks";
 import {
   contextCollector,
@@ -198,6 +199,10 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
     ? createSisyphusOrchestratorHook(ctx)
     : null;
 
+  const prometheusMdOnly = isHookEnabled("prometheus-md-only")
+    ? createPrometheusMdOnlyHook(ctx)
+    : null;
+
   const taskResumeInfo = createTaskResumeInfoHook();
 
   const backgroundManager = new BackgroundManager(ctx);
@@ -451,6 +456,7 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
       await directoryAgentsInjector?.["tool.execute.before"]?.(input, output);
       await directoryReadmeInjector?.["tool.execute.before"]?.(input, output);
       await rulesInjector?.["tool.execute.before"]?.(input, output);
+      await prometheusMdOnly?.["tool.execute.before"]?.(input, output);
 
       if (input.tool === "task") {
         const args = output.args as Record<string, unknown>;

src/tools/sisyphus-task/tools.ts

@@ -243,6 +243,19 @@ System notifies on completion. Use \`background_output\` with task_id="${task.id
       }
 
       try {
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        const tuiClient = client as any
+        if (tuiClient.tui?.showToast) {
+          tuiClient.tui.showToast({
+            body: {
+              title: "Task Started",
+              message: `"${args.description}" running with ${agentToUse}`,
+              variant: "info",
+              duration: 3000,
+            },
+          }).catch(() => {})
+        }
+
         const createResult = await client.session.create({
           body: {
             parentID: ctx.sessionID,