diff --git a/packages/desktop-electron/src/main/cli.ts b/packages/desktop-electron/src/main/cli.ts
index fba301f36..f2d918bd2 100644
--- a/packages/desktop-electron/src/main/cli.ts
+++ b/packages/desktop-electron/src/main/cli.ts
@@ -35,6 +35,7 @@ export type CommandEvent =
 export type SqliteMigrationProgress = { type: "InProgress"; value: number } | { type: "Done" }
 
 export type CommandChild = {
+  pid: number | undefined
   kill: () => void
 }
 
@@ -191,7 +192,7 @@ export function spawnCommand(args: string, extraEnv: Record<string, string>) {
     treeKill(child.pid)
   }
 
-  return { events, child: { kill }, exit }
+  return { events, child: { pid: child.pid, kill }, exit }
 }
 
 function handleSqliteProgress(events: EventEmitter, line: string) {
diff --git a/packages/desktop-electron/src/main/index.ts b/packages/desktop-electron/src/main/index.ts
index 484e4feb2..032343204 100644
--- a/packages/desktop-electron/src/main/index.ts
+++ b/packages/desktop-electron/src/main/index.ts
@@ -81,6 +81,17 @@ function setupApp() {
     killSidecar()
   })
 
+  app.on("will-quit", () => {
+    killSidecar()
+  })
+
+  for (const signal of ["SIGINT", "SIGTERM"] as const) {
+    process.on(signal, () => {
+      killSidecar()
+      app.exit(0)
+    })
+  }
+
   void app.whenReady().then(async () => {
     // migrate()
     app.setAsDefaultProtocolClient("opencode")
@@ -234,8 +245,15 @@ registerIpcHandlers({
 
 function killSidecar() {
   if (!sidecar) return
+  const pid = sidecar.pid
   sidecar.kill()
   sidecar = null
+  // tree-kill is async; also send process group signal as immediate fallback
+  if (pid && process.platform !== "win32") {
+    try {
+      process.kill(-pid, "SIGTERM")
+    } catch {}
+  }
 }
 
 function ensureLoopbackNoProxy() {