diff --git a/packages/opencode/test/plugin/trigger.test.ts b/packages/opencode/test/plugin/trigger.test.ts
new file mode 100644
index 000000000000..d89d930c69ea
--- /dev/null
+++ b/packages/opencode/test/plugin/trigger.test.ts
@@ -0,0 +1,111 @@
+import { afterAll, afterEach, describe, expect, test } from "bun:test"
+import path from "path"
+import { pathToFileURL } from "url"
+import { tmpdir } from "../fixture/fixture"
+
+const disableDefault = process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS
+process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS = "1"
+
+const { Plugin } = await import("../../src/plugin/index")
+const { Instance } = await import("../../src/project/instance")
+
+afterEach(async () => {
+  await Instance.disposeAll()
+})
+
+afterAll(() => {
+  if (disableDefault === undefined) {
+    delete process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS
+    return
+  }
+  process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS = disableDefault
+})
+
+async function project(source: string) {
+  return tmpdir({
+    init: async (dir) => {
+      const file = path.join(dir, "plugin.ts")
+      await Bun.write(file, source)
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify(
+          {
+            $schema: "https://opencode.ai/config.json",
+            plugin: [pathToFileURL(file).href],
+          },
+          null,
+          2,
+        ),
+      )
+    },
+  })
+}
+
+describe("plugin.trigger", () => {
+  test("runs synchronous hooks without crashing", async () => {
+    await using tmp = await project(
+      [
+        "export default async () => ({",
+        '  "experimental.chat.system.transform": (_input, output) => {',
+        '    output.system.unshift("sync")',
+        "  },",
+        "})",
+        "",
+      ].join("\n"),
+    )
+
+    const out = await Instance.provide({
+      directory: tmp.path,
+      fn: async () => {
+        const out = { system: [] as string[] }
+        await Plugin.trigger(
+          "experimental.chat.system.transform",
+          {
+            model: {
+              providerID: "anthropic",
+              modelID: "claude-sonnet-4-6",
+            } as any,
+          },
+          out,
+        )
+        return out
+      },
+    })
+
+    expect(out.system).toEqual(["sync"])
+  })
+
+  test("awaits asynchronous hooks", async () => {
+    await using tmp = await project(
+      [
+        "export default async () => ({",
+        '  "experimental.chat.system.transform": async (_input, output) => {',
+        "    await Bun.sleep(1)",
+        '    output.system.unshift("async")',
+        "  },",
+        "})",
+        "",
+      ].join("\n"),
+    )
+
+    const out = await Instance.provide({
+      directory: tmp.path,
+      fn: async () => {
+        const out = { system: [] as string[] }
+        await Plugin.trigger(
+          "experimental.chat.system.transform",
+          {
+            model: {
+              providerID: "anthropic",
+              modelID: "claude-sonnet-4-6",
+            } as any,
+          },
+          out,
+        )
+        return out
+      },
+    })
+
+    expect(out.system).toEqual(["async"])
+  })
+})