diff --git a/packages/opencode/src/cli/cmd/tui/app.tsx b/packages/opencode/src/cli/cmd/tui/app.tsx
index ec048f86b2f1..aba55da368f4 100644
--- a/packages/opencode/src/cli/cmd/tui/app.tsx
+++ b/packages/opencode/src/cli/cmd/tui/app.tsx
@@ -16,7 +16,7 @@ import {
   on,
   onCleanup,
 } from "solid-js"
-import { win32DisableProcessedInput, win32InstallCtrlCGuard } from "./win32"
+import { win32DisableProcessedInput, win32InstallCtrlCGuard, win32ResetTerminal } from "./win32"
 import { Flag } from "@/flag/flag"
 import semver from "semver"
 import { DialogProvider, useDialog } from "@tui/ui/dialog"
@@ -182,6 +182,8 @@ export function tui(input: {
     win32DisableProcessedInput()
 
     const onExit = async () => {
+      // Reset terminal on Windows to prevent ANSI corruption (issue #20224)
+      win32ResetTerminal()
       unguard?.()
       resolve()
     }
diff --git a/packages/opencode/src/cli/cmd/tui/attach.ts b/packages/opencode/src/cli/cmd/tui/attach.ts
index e892f9922d1b..77e1153fd14e 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, win32ResetTerminal } from "./win32"
 import { TuiConfig } from "@/config/tui"
 import { Instance } from "@/project/instance"
 import { existsSync } from "fs"
@@ -82,6 +82,8 @@ export const AttachCommand = cmd({
         headers,
       })
     } finally {
+      // Reset terminal on Windows to prevent ANSI corruption (issue #20224)
+      win32ResetTerminal()
       unguard?.()
     }
   },
diff --git a/packages/opencode/src/cli/cmd/tui/win32.ts b/packages/opencode/src/cli/cmd/tui/win32.ts
index 23e9f448574f..5b8515bb1433 100644
--- a/packages/opencode/src/cli/cmd/tui/win32.ts
+++ b/packages/opencode/src/cli/cmd/tui/win32.ts
@@ -1,7 +1,11 @@
 import { dlopen, ptr } from "bun:ffi"
 
+const STD_OUTPUT_HANDLE = -11
+const STD_ERROR_HANDLE = -12
 const STD_INPUT_HANDLE = -10
 const ENABLE_PROCESSED_INPUT = 0x0001
+const ENABLE_VIRTUAL_TERMINAL_PROCESSING = 0x0004
+const ENABLE_WRAP_AT_EOL_OUTPUT = 0x0002
 
 const kernel = () =>
   dlopen("kernel32.dll", {
@@ -23,6 +27,41 @@ function load() {
   }
 }
 
+/**
+ * Reset terminal to a clean state on Windows.
+ * This clears any pending output and restores proper console modes.
+ */
+export function win32ResetTerminal() {
+  if (process.platform !== "win32") return
+  if (!load()) return
+
+  try {
+    // Clear any pending output buffers
+    const outputHandle = k32!.symbols.GetStdHandle(STD_OUTPUT_HANDLE)
+    const errorHandle = k32!.symbols.GetStdHandle(STD_ERROR_HANDLE)
+
+    // Reset output console modes to enable proper ANSI processing
+    const buf = new Uint32Array(1)
+    if (k32!.symbols.GetConsoleMode(outputHandle, ptr(buf)) !== 0) {
+      const mode = buf[0]! | ENABLE_VIRTUAL_TERMINAL_PROCESSING | ENABLE_WRAP_AT_EOL_OUTPUT
+      k32!.symbols.SetConsoleMode(outputHandle, mode)
+    }
+    if (k32!.symbols.GetConsoleMode(errorHandle, ptr(buf)) !== 0) {
+      const mode = buf[0]! | ENABLE_VIRTUAL_TERMINAL_PROCESSING | ENABLE_WRAP_AT_EOL_OUTPUT
+      k32!.symbols.SetConsoleMode(errorHandle, mode)
+    }
+
+    // Clear the screen and reset cursor position
+    process.stdout.write("\x1b[2J\x1b[H")
+    // Reset all SGR (Select Graphic Rendition) attributes
+    process.stdout.write("\x1b[0m")
+    // Disable any alternate screen buffer
+    process.stdout.write("\x1b[?1049l")
+  } catch {
+    // Ignore errors during terminal reset
+  }
+}
+
 /**
  * Clear ENABLE_PROCESSED_INPUT on the console stdin handle.
  */