From 8c1946e2da633fe58c05ad7c24f8a46631298fdd Mon Sep 17 00:00:00 2001
From: OrcaWin <alpha-eng@stably.ai>
Date: Thu, 30 Jul 2026 21:40:53 -0700
Subject: [PATCH] perf(terminal): keep uncontended paste delivery synchronous

---
 .../terminal-paste-operation-order.test.ts             | 10 ++++++++++
 .../terminal-pane/terminal-pty-input-transaction.ts    |  6 ++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/renderer/src/components/terminal-pane/terminal-paste-operation-order.test.ts b/src/renderer/src/components/terminal-pane/terminal-paste-operation-order.test.ts
index b0f874d50f8..b36f0d06f65 100644
--- a/src/renderer/src/components/terminal-pane/terminal-paste-operation-order.test.ts
+++ b/src/renderer/src/components/terminal-pane/terminal-paste-operation-order.test.ts
@@ -32,6 +32,16 @@ function chunkedWindowsPaste() {
 }
 
 describe('terminal paste operation ordering', () => {
+  it('starts an uncontended paste operation synchronously', async () => {
+    let started = false
+    const operation = runTerminalPtyInputTransaction('pty-1', async () => {
+      started = true
+    })
+
+    expect(started).toBe(true)
+    await operation
+  })
+
   it('keeps startup context outside an active chunked user paste frame', async () => {
     const writes: string[] = []
     let startupDraft: Promise<boolean> | null = null
diff --git a/src/renderer/src/components/terminal-pane/terminal-pty-input-transaction.ts b/src/renderer/src/components/terminal-pane/terminal-pty-input-transaction.ts
index 8a4303bcc5f..e6c0239751b 100644
--- a/src/renderer/src/components/terminal-pane/terminal-pty-input-transaction.ts
+++ b/src/renderer/src/components/terminal-pane/terminal-pty-input-transaction.ts
@@ -8,14 +8,16 @@ export async function runTerminalPtyInputTransaction<T>(
     return await operation()
   }
 
-  const previous = transactionTails.get(ptyId) ?? Promise.resolve()
+  const previous = transactionTails.get(ptyId)
   let release!: () => void
   const current = new Promise<void>((resolve) => {
     release = resolve
   })
   transactionTails.set(ptyId, current)
 
-  await previous
+  if (previous) {
+    await previous
+  }
   try {
     return await operation()
   } finally {