fix(app): terminal pty isolation

2 files changed, 60 insertions, 0 deletions

diff --git a/packages/app/src/utils/terminal-writer.test.ts b/packages/app/src/utils/terminal-writer.test.ts
new file mode 100644
index 000000000..d48dd4f4e
--- /dev/null
+++ b/packages/app/src/utils/terminal-writer.test.ts
@@ -0,0 +1,33 @@
+import { describe, expect, test } from "bun:test"
+import { terminalWriter } from "./terminal-writer"
+
+describe("terminalWriter", () => {
+  test("buffers and flushes once per schedule", () => {
+    const calls: string[] = []
+    const scheduled: VoidFunction[] = []
+    const writer = terminalWriter(
+      (data) => calls.push(data),
+      (flush) => scheduled.push(flush),
+    )
+
+    writer.push("a")
+    writer.push("b")
+    writer.push("c")
+
+    expect(calls).toEqual([])
+    expect(scheduled).toHaveLength(1)
+
+    scheduled[0]?.()
+    expect(calls).toEqual(["abc"])
+  })
+
+  test("flush is a no-op when empty", () => {
+    const calls: string[] = []
+    const writer = terminalWriter(
+      (data) => calls.push(data),
+      (flush) => flush(),
+    )
+    writer.flush()
+    expect(calls).toEqual([])
+  })
+})
diff --git a/packages/app/src/utils/terminal-writer.ts b/packages/app/src/utils/terminal-writer.ts
new file mode 100644
index 000000000..b6caff789
--- /dev/null
+++ b/packages/app/src/utils/terminal-writer.ts
@@ -0,0 +1,27 @@
+export function terminalWriter(
+  write: (data: string) => void,
+  schedule: (flush: VoidFunction) => void = queueMicrotask,
+) {
+  let chunks: string[] | undefined
+  let scheduled = false
+
+  const flush = () => {
+    scheduled = false
+    const items = chunks
+    if (!items?.length) return
+    chunks = undefined
+    write(items.join(""))
+  }
+
+  const push = (data: string) => {
+    if (!data) return
+    if (chunks) chunks.push(data)
+    else chunks = [data]
+
+    if (scheduled) return
+    scheduled = true
+    schedule(flush)
+  }
+
+  return { push, flush }
+}