diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..290f4c3
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,17 @@
+name: Tests
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: oven-sh/setup-bun@v2
+      - run: bun install --frozen-lockfile
+      - name: Typecheck
+        run: bun run typecheck
+      - name: Tests
+        run: bun test
diff --git a/src/index.ts b/src/index.ts
index 551148e..745211a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -7,12 +7,12 @@ import { warpNotify } from "./notify"
 const PLUGIN_VERSION = "0.1.0"
 const NOTIFICATION_TITLE = "warp://cli-agent"
 
-function truncate(str: string, maxLen: number): string {
+export function truncate(str: string, maxLen: number): string {
   if (str.length <= maxLen) return str
   return str.slice(0, maxLen - 3) + "..."
 }
 
-function extractTextFromParts(parts: Part[]): string {
+export function extractTextFromParts(parts: Part[]): string {
   return parts
     .filter((p): p is Part & { type: "text"; text: string } =>
       p.type === "text" && "text" in p && Boolean(p.text),
@@ -125,31 +125,10 @@ export const WarpPlugin: Plugin = async ({ client, directory }) => {
           return
         }
 
-        case "message.updated": {
-          const message = event.properties.info
-          if (message.role !== "user") return
-
-          const sessionId = message.sessionID
-
-          // message.updated doesn't carry parts directly — fetch the message
-          let queryText = ""
-          try {
-            const result = await client.session.message({
-              path: { id: sessionId, messageID: message.id },
-            })
-            if (result.data) {
-              queryText = extractTextFromParts(result.data.parts)
-            }
-          } catch {
-            // Fall back to using summary title if available
-            queryText = message.summary?.title ?? ""
-          }
-
-          if (!queryText) return
-
-          const body = buildPayload("prompt_submit", sessionId, cwd, {
-            query: truncate(queryText, 200),
-          })
+        case "permission.replied": {
+          const { sessionID, response } = event.properties
+          if (response === "reject") return
+          const body = buildPayload("permission_replied", sessionID, cwd)
           warpNotify(NOTIFICATION_TITLE, body)
           return
         }
@@ -164,6 +143,21 @@ export const WarpPlugin: Plugin = async ({ client, directory }) => {
       }
     },
 
+    // Fires once per new user message — used to send the prompt_submit hook.
+    // (We avoid the generic message.updated event because OpenCode fires it
+    // multiple times per message, and a late duplicate can clobber the
+    // completion notification.)
+    "chat.message": async (input, output) => {
+      const cwd = directory || ""
+      const queryText = extractTextFromParts(output.parts)
+      if (!queryText) return
+
+      const body = buildPayload("prompt_submit", input.sessionID, cwd, {
+        query: truncate(queryText, 200),
+      })
+      warpNotify(NOTIFICATION_TITLE, body)
+    },
+
     // Tool completion — fires after every tool call
     "tool.execute.after": async (input) => {
       const toolName = input.tool
diff --git a/tests/index.test.ts b/tests/index.test.ts
new file mode 100644
index 0000000..74cb408
--- /dev/null
+++ b/tests/index.test.ts
@@ -0,0 +1,63 @@
+import { describe, it } from "node:test"
+import assert from "node:assert/strict"
+import { truncate, extractTextFromParts } from "../src/index"
+
+describe("truncate", () => {
+  it("returns string unchanged when under maxLen", () => {
+    assert.strictEqual(truncate("hello", 10), "hello")
+  })
+
+  it("returns string unchanged when exactly maxLen", () => {
+    assert.strictEqual(truncate("hello", 5), "hello")
+  })
+
+  it("truncates and adds ellipsis when over maxLen", () => {
+    assert.strictEqual(truncate("hello world", 8), "hello...")
+  })
+
+  it("handles maxLen of 3 (minimum for ellipsis)", () => {
+    assert.strictEqual(truncate("hello", 3), "...")
+  })
+
+  it("handles empty string", () => {
+    assert.strictEqual(truncate("", 10), "")
+  })
+})
+
+describe("extractTextFromParts", () => {
+  it("extracts text from text parts", () => {
+    const parts = [
+      { type: "text" as const, text: "hello" },
+      { type: "text" as const, text: "world" },
+    ]
+    assert.strictEqual(extractTextFromParts(parts), "hello world")
+  })
+
+  it("skips non-text parts", () => {
+    const parts = [
+      { type: "text" as const, text: "hello" },
+      { type: "tool_use" as const, id: "1", name: "bash", input: {} },
+      { type: "text" as const, text: "world" },
+    ] as any[]
+    assert.strictEqual(extractTextFromParts(parts), "hello world")
+  })
+
+  it("skips text parts with empty text", () => {
+    const parts = [
+      { type: "text" as const, text: "" },
+      { type: "text" as const, text: "hello" },
+    ]
+    assert.strictEqual(extractTextFromParts(parts), "hello")
+  })
+
+  it("returns empty string for no parts", () => {
+    assert.strictEqual(extractTextFromParts([]), "")
+  })
+
+  it("returns empty string when all parts are non-text", () => {
+    const parts = [
+      { type: "tool_use" as const, id: "1", name: "bash", input: {} },
+    ] as any[]
+    assert.strictEqual(extractTextFromParts(parts), "")
+  })
+})
diff --git a/tests/notify.test.ts b/tests/notify.test.ts
new file mode 100644
index 0000000..358edbd
--- /dev/null
+++ b/tests/notify.test.ts
@@ -0,0 +1,49 @@
+import { describe, it, afterEach, mock } from "bun:test"
+import { expect } from "bun:test"
+import fs from "fs"
+
+const writeSpy = mock(() => {})
+mock.module("fs", () => ({
+  ...fs,
+  writeFileSync: writeSpy,
+}))
+
+const { warpNotify } = await import("../src/notify")
+
+describe("warpNotify", () => {
+  const originalTermProgram = process.env.TERM_PROGRAM
+
+  afterEach(() => {
+    writeSpy.mockClear()
+    if (originalTermProgram === undefined) {
+      delete process.env.TERM_PROGRAM
+    } else {
+      process.env.TERM_PROGRAM = originalTermProgram
+    }
+  })
+
+  it("skips when TERM_PROGRAM is not set", () => {
+    delete process.env.TERM_PROGRAM
+    warpNotify("title", "body")
+    expect(writeSpy).not.toHaveBeenCalled()
+  })
+
+  it("skips for other terminal programs", () => {
+    process.env.TERM_PROGRAM = "iTerm.app"
+    warpNotify("title", "body")
+    expect(writeSpy).not.toHaveBeenCalled()
+  })
+
+  it("writes OSC 777 sequence when inside Warp", () => {
+    process.env.TERM_PROGRAM = "WarpTerminal"
+    warpNotify("warp://cli-agent", '{"event":"stop"}')
+    expect(writeSpy).toHaveBeenCalledTimes(1)
+
+    const [path, data] = writeSpy.mock.calls[0] as [string, string]
+    expect(path).toBe("/dev/tty")
+    expect(data).toContain("warp://cli-agent")
+    expect(data).toContain('{"event":"stop"}')
+    expect(data).toMatch(/^\x1b\]777;notify;/)
+    expect(data).toMatch(/\x07$/)
+  })
+})