diff --git a/packages/app/script/e2e-local.ts b/packages/app/script/e2e-local.ts
index 112e2bc60a1..9a83411b1d2 100644
--- a/packages/app/script/e2e-local.ts
+++ b/packages/app/script/e2e-local.ts
@@ -145,6 +145,7 @@ try {
     Object.assign(process.env, serverEnv)
     process.env.AGENT = "1"
     process.env.OPENCODE = "1"
+    process.env.OPENCODE_PID = String(process.pid)
 
     const log = await import("../../opencode/src/util/log")
     const install = await import("../../opencode/src/installation")
diff --git a/packages/opencode/src/index.ts b/packages/opencode/src/index.ts
index 9af79278c06..35b42dce77c 100644
--- a/packages/opencode/src/index.ts
+++ b/packages/opencode/src/index.ts
@@ -76,6 +76,7 @@ let cli = yargs(hideBin(process.argv))
 
     process.env.AGENT = "1"
     process.env.OPENCODE = "1"
+    process.env.OPENCODE_PID = String(process.pid)
 
     Log.Default.info("opencode", {
       version: Installation.VERSION,
diff --git a/packages/opencode/src/mcp/index.ts b/packages/opencode/src/mcp/index.ts
index 3c29fe03d30..0dca27d6512 100644
--- a/packages/opencode/src/mcp/index.ts
+++ b/packages/opencode/src/mcp/index.ts
@@ -160,6 +160,28 @@ export namespace MCP {
     return typeof entry === "object" && entry !== null && "type" in entry
   }
 
+  async function descendants(pid: number): Promise<number[]> {
+    if (process.platform === "win32") return []
+    const pids: number[] = []
+    const queue = [pid]
+    while (queue.length > 0) {
+      const current = queue.shift()!
+      const proc = Bun.spawn(["pgrep", "-P", String(current)], { stdout: "pipe", stderr: "pipe" })
+      const [code, out] = await Promise.all([proc.exited, new Response(proc.stdout).text()]).catch(
+        () => [-1, ""] as const,
+      )
+      if (code !== 0) continue
+      for (const tok of out.trim().split(/\s+/)) {
+        const cpid = parseInt(tok, 10)
+        if (!isNaN(cpid) && pids.indexOf(cpid) === -1) {
+          pids.push(cpid)
+          queue.push(cpid)
+        }
+      }
+    }
+    return pids
+  }
+
   const state = Instance.state(
     async () => {
       const cfg = await Config.get()
@@ -196,6 +218,21 @@ export namespace MCP {
       }
     },
     async (state) => {
+      // The MCP SDK only signals the direct child process on close.
+      // Servers like chrome-devtools-mcp spawn grandchild processes
+      // (e.g. Chrome) that the SDK never reaches, leaving them orphaned.
+      // Kill the full descendant tree first so the server exits promptly
+      // and no processes are left behind.
+      for (const client of Object.values(state.clients)) {
+        const pid = (client.transport as any)?.pid
+        if (typeof pid !== "number") continue
+        for (const dpid of await descendants(pid)) {
+          try {
+            process.kill(dpid, "SIGTERM")
+          } catch {}
+        }
+      }
+
       await Promise.all(
         Object.values(state.clients).map((client) =>
           client.close().catch((error) => {