fix(core): await plugin readiness

packages/core/test/plugin.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect } from "bun:test"
-import { Effect } from "effect"
+import { Effect, Exit, Fiber } from "effect"
 import { define } from "@opencode-ai/plugin/v2/effect"
 import { AgentV2 } from "@opencode-ai/core/agent"
 import { PluginV2 } from "@opencode-ai/core/plugin"
@@ -9,6 +9,34 @@ import { PluginTestLayer } from "./plugin/fixture"
 const it = testEffect(PluginTestLayer)
 
 describe("PluginV2", () => {
+  it.effect("waits for a plugin and returns immediately once active", () =>
+    Effect.gen(function* () {
+      const plugins = yield* PluginV2.Service
+      const id = PluginV2.ID.make("waited")
+      const waiting = yield* plugins.wait(id).pipe(Effect.forkChild)
+
+      yield* plugins.add(id, () => Effect.void)
+      yield* Fiber.join(waiting)
+      yield* plugins.wait(id)
+    }),
+  )
+
+  it.effect("propagates plugin activation defects to waiters", () =>
+    Effect.gen(function* () {
+      const plugins = yield* PluginV2.Service
+      const id = PluginV2.ID.make("failed")
+      const waiting = yield* plugins.wait(id).pipe(Effect.exit, Effect.forkChild)
+
+      const added = yield* plugins.add(id, () => Effect.die("boom")).pipe(Effect.exit)
+      const pending = yield* Fiber.join(waiting)
+      const later = yield* plugins.wait(id).pipe(Effect.exit)
+
+      expect(Exit.isFailure(added)).toBe(true)
+      expect(Exit.isFailure(pending)).toBe(true)
+      expect(Exit.isFailure(later)).toBe(true)
+    }),
+  )
+
   it.effect("adds, replaces, and removes plugins", () =>
     Effect.gen(function* () {
       const plugins = yield* PluginV2.Service