diff --git a/plugins/opencode/osc99-notify.js b/plugins/opencode/osc99-notify.js
new file mode 100644
index 0000000..e6fa7e3
--- /dev/null
+++ b/plugins/opencode/osc99-notify.js
@@ -0,0 +1,70 @@
+// OSC 99 Desktop Notifications for OpenCode
+//
+// Sends desktop notifications via the OSC 99 escape sequence protocol
+// when OpenCode needs your attention. Notifications are only shown when
+// the terminal window is unfocused (o=unfocused).
+//
+// Tested with: Kitty terminal
+// May also work with other terminals that support the OSC 99 protocol.
+//
+// Features:
+//   - Notifies when a session goes idle (waiting for your input)
+//   - Notifies when a question is asked (e.g. multiple choice)
+//   - Notifies when a permission prompt is raised
+//   - Notifies when a session error occurs
+//   - Includes the project directory name in the notification title
+//   - Suppresses notifications from subagent sessions (e.g. Explore Task)
+//   - Suppresses notifications when the terminal window is focused
+//   - Uses distinct sounds per notification type (system, question, error)
+//
+// Installation:
+//   Copy this file to ~/.config/opencode/plugins/osc99-notify.js
+//
+// Notification types:
+//   Idle:       title  ->  OpenCode (project-name)
+//               body   ->  Waiting for your input
+//               sound  ->  system
+//
+//   Question:   title  ->  OpenCode (project-name)
+//               body   ->  Has a question for you
+//               sound  ->  question
+//
+//   Permission: title  ->  OpenCode (project-name)
+//               body   ->  Needs your permission
+//               sound  ->  question
+//
+//   Error:      title  ->  OpenCode (project-name)
+//               body   ->  Encountered an error
+//               sound  ->  error
+
+export const OSC99Notify = async ({ client }) => {
+  const path = require('path')
+  const project = path.basename(process.cwd())
+  let id = 0
+
+  const notify = (icon, message, sound = 'system') => {
+    id++
+    process.stderr.write(`\x1b]99;i=${id}:d=0:s=${sound}:o=unfocused;${icon} OpenCode (${project})\x1b\\`)
+    process.stderr.write(`\x1b]99;i=${id}:p=body;${message}\x1b\\`)
+  }
+
+  return {
+    event: async ({ event }) => {
+      if (event.type === "message.part.updated" && event.properties.part.type === "tool" && event.properties.part.tool === "question" && event.properties.part.state?.status === "pending")
+        notify('❓', 'Has a question for you', 'question')
+
+      if (event.type === "session.idle") {
+        const session = await client.session.get({ path: { id: event.properties.sessionID } })
+        if (!session.data?.parentID)
+          notify('🤖', 'Waiting for your input')
+      }
+      if (event.type === "session.error") {
+        const session = await client.session.get({ path: { id: event.properties.sessionID } })
+        if (!session.data?.parentID)
+          notify('🚨', 'Encountered an error', 'error')
+      }
+      if (event.type === "permission.updated")
+        notify('🔐', 'Needs your permission', 'question')
+    },
+  }
+}