From 94fce4c3a6e5ebee828694f8fdf521c083f9de50 Mon Sep 17 00:00:00 2001
From: mikemikimike <13286568797@163.com>
Date: Sun, 16 Aug 2026 08:16:53 +0800
Subject: [PATCH 1/2] fix: resolve local process wait after child close

---
 .changeset/fix-local-process-wait.md              |  5 +++++
 packages/ai-sandbox-local-process/src/handle.ts   | 13 ++++++++-----
 .../tests/local-process.test.ts                   | 15 +++++++++++++++
 3 files changed, 28 insertions(+), 5 deletions(-)
 create mode 100644 .changeset/fix-local-process-wait.md

diff --git a/.changeset/fix-local-process-wait.md b/.changeset/fix-local-process-wait.md
new file mode 100644
index 0000000000..4c2bfec80c
--- /dev/null
+++ b/.changeset/fix-local-process-wait.md
@@ -0,0 +1,5 @@
+---
+'@tanstack/ai-sandbox-local-process': patch
+---
+
+Fix local-process spawn handles hanging when the child exits before `wait()` is called.
diff --git a/packages/ai-sandbox-local-process/src/handle.ts b/packages/ai-sandbox-local-process/src/handle.ts
index 28aa873bb9..a48c5907ce 100644
--- a/packages/ai-sandbox-local-process/src/handle.ts
+++ b/packages/ai-sandbox-local-process/src/handle.ts
@@ -340,6 +340,13 @@ export class LocalProcessHandle implements SandboxHandle {
         once: true,
       })
     }
+    const closed = new Promise<number>((resolve, reject) => {
+      child.once('error', reject)
+      child.once('close', (code) => resolve(code ?? 0))
+    })
+    // The child can close while stdout is still being drained. Keep the
+    // rejection handled until the caller asks for the result via wait().
+    closed.catch(() => {})
     const handle: SpawnHandle = {
       pid: child.pid ?? -1,
       stdout: decodeStream(child.stdout),
@@ -354,11 +361,7 @@ export class LocalProcessHandle implements SandboxHandle {
             child.stdin.end(() => resolve())
           }),
       },
-      wait: () =>
-        new Promise<number>((resolve, reject) => {
-          child.on('error', reject)
-          child.on('close', (code) => resolve(code ?? 0))
-        }),
+      wait: () => closed,
       kill: (signal) => {
         killTree(child, signal)
         return Promise.resolve()
diff --git a/packages/ai-sandbox-local-process/tests/local-process.test.ts b/packages/ai-sandbox-local-process/tests/local-process.test.ts
index af949c7933..9501019918 100644
--- a/packages/ai-sandbox-local-process/tests/local-process.test.ts
+++ b/packages/ai-sandbox-local-process/tests/local-process.test.ts
@@ -88,6 +88,21 @@ describe('local-process process', () => {
     expect(code).toBe(0)
     await sbx.destroy()
   })
+
+  it('resolves wait() when the child closes before stdout is fully consumed', async () => {
+    const sbx = await fresh()
+    const proc = await sbx.process.spawn(
+      `node -e "for (let i = 0; i < 20; i++) console.log(i)"`,
+    )
+    let out = ''
+    for await (const chunk of proc.stdout) {
+      out += chunk
+      await new Promise((resolve) => setTimeout(resolve, 10))
+    }
+    await expect(proc.wait()).resolves.toBe(0)
+    expect(out.split('\n').filter(Boolean)).toHaveLength(20)
+    await sbx.destroy()
+  })
 })
 
 describe('local-process + spawnNdjson (real agent-CLI streaming)', () => {

From 9472ccba992a897a42eb2fbbbaac1cac3875f103 Mon Sep 17 00:00:00 2001
From: mikemikimike <13286568797@163.com>
Date: Sun, 16 Aug 2026 08:50:01 +0800
Subject: [PATCH 2/2] test: assert local process output ordering

---
 .../ai-sandbox-local-process/tests/local-process.test.ts     | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/ai-sandbox-local-process/tests/local-process.test.ts b/packages/ai-sandbox-local-process/tests/local-process.test.ts
index 9501019918..b77586c261 100644
--- a/packages/ai-sandbox-local-process/tests/local-process.test.ts
+++ b/packages/ai-sandbox-local-process/tests/local-process.test.ts
@@ -100,7 +100,10 @@ describe('local-process process', () => {
       await new Promise((resolve) => setTimeout(resolve, 10))
     }
     await expect(proc.wait()).resolves.toBe(0)
-    expect(out.split('\n').filter(Boolean)).toHaveLength(20)
+    const lines = out.trimEnd().split(/\r?\n/)
+    expect(lines).toEqual(
+      Array.from({ length: 20 }, (_, index) => String(index)),
+    )
     await sbx.destroy()
   })
 })