From 4133bd8c3184c74efd56a76c3fcae51fed556c7f Mon Sep 17 00:00:00 2001
From: User <user@example.com>
Date: Mon, 23 Feb 2026 17:36:10 +0800
Subject: [PATCH] fix: set Windows console code page to UTF-8 for CJK input

---
 packages/opencode/src/cli/cmd/tui/attach.ts |  3 ++-
 packages/opencode/src/cli/cmd/tui/thread.ts |  3 ++-
 packages/opencode/src/cli/cmd/tui/win32.ts  | 15 +++++++++++++++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/packages/opencode/src/cli/cmd/tui/attach.ts b/packages/opencode/src/cli/cmd/tui/attach.ts
index a2559cfce67..b66bfdf5395 100644
--- a/packages/opencode/src/cli/cmd/tui/attach.ts
+++ b/packages/opencode/src/cli/cmd/tui/attach.ts
@@ -1,7 +1,7 @@
 import { cmd } from "../cmd"
 import { UI } from "@/cli/ui"
 import { tui } from "./app"
-import { win32DisableProcessedInput, win32InstallCtrlCGuard } from "./win32"
+import { win32DisableProcessedInput, win32InstallCtrlCGuard, win32SetUtf8CodePage } from "./win32"
 
 export const AttachCommand = cmd({
   command: "attach <url>",
@@ -40,6 +40,7 @@ export const AttachCommand = cmd({
     const unguard = win32InstallCtrlCGuard()
     try {
       win32DisableProcessedInput()
+      win32SetUtf8CodePage()
 
       if (args.fork && !args.continue && !args.session) {
         UI.error("--fork requires --continue or --session")
diff --git a/packages/opencode/src/cli/cmd/tui/thread.ts b/packages/opencode/src/cli/cmd/tui/thread.ts
index 50f63c3dfbd..585cadb02a7 100644
--- a/packages/opencode/src/cli/cmd/tui/thread.ts
+++ b/packages/opencode/src/cli/cmd/tui/thread.ts
@@ -11,7 +11,7 @@ import { withNetworkOptions, resolveNetworkOptions } from "@/cli/network"
 import { Filesystem } from "@/util/filesystem"
 import type { Event } from "@opencode-ai/sdk/v2"
 import type { EventSource } from "./context/sdk"
-import { win32DisableProcessedInput, win32InstallCtrlCGuard } from "./win32"
+import { win32DisableProcessedInput, win32InstallCtrlCGuard, win32SetUtf8CodePage } from "./win32"
 
 declare global {
   const OPENCODE_WORKER_PATH: string
@@ -87,6 +87,7 @@ export const TuiThreadCommand = cmd({
       // Must be the very first thing — disables CTRL_C_EVENT before any Worker
       // spawn or async work so the OS cannot kill the process group.
       win32DisableProcessedInput()
+      win32SetUtf8CodePage()
 
       if (args.fork && !args.continue && !args.session) {
         UI.error("--fork requires --continue or --session")
diff --git a/packages/opencode/src/cli/cmd/tui/win32.ts b/packages/opencode/src/cli/cmd/tui/win32.ts
index 23e9f448574..4f0946c59db 100644
--- a/packages/opencode/src/cli/cmd/tui/win32.ts
+++ b/packages/opencode/src/cli/cmd/tui/win32.ts
@@ -2,6 +2,7 @@ import { dlopen, ptr } from "bun:ffi"
 
 const STD_INPUT_HANDLE = -10
 const ENABLE_PROCESSED_INPUT = 0x0001
+const CP_UTF8 = 65001
 
 const kernel = () =>
   dlopen("kernel32.dll", {
@@ -9,6 +10,8 @@ const kernel = () =>
     GetConsoleMode: { args: ["ptr", "ptr"], returns: "i32" },
     SetConsoleMode: { args: ["ptr", "u32"], returns: "i32" },
     FlushConsoleInputBuffer: { args: ["ptr"], returns: "i32" },
+    SetConsoleCP: { args: ["u32"], returns: "i32" },
+    SetConsoleOutputCP: { args: ["u32"], returns: "i32" },
   })
 
 let k32: ReturnType<typeof kernel> | undefined
@@ -23,6 +26,18 @@ function load() {
   }
 }
 
+/**
+ * Set console code page to UTF-8 for proper Unicode input/output.
+ * This fixes character encoding issues when using CJK (Chinese, Japanese, Korean)
+ * and other non-ASCII input methods on Windows.
+ */
+export function win32SetUtf8CodePage() {
+  if (process.platform !== "win32") return
+  if (!load()) return
+  k32!.symbols.SetConsoleCP(CP_UTF8)
+  k32!.symbols.SetConsoleOutputCP(CP_UTF8)
+}
+
 /**
  * Clear ENABLE_PROCESSED_INPUT on the console stdin handle.
  */