diff --git a/packages/opencode/src/cli/cmd/tui/component/prompt/autocomplete.tsx b/packages/opencode/src/cli/cmd/tui/component/prompt/autocomplete.tsx
index 3f7604653c56..aa2c25939a0d 100644
--- a/packages/opencode/src/cli/cmd/tui/component/prompt/autocomplete.tsx
+++ b/packages/opencode/src/cli/cmd/tui/component/prompt/autocomplete.tsx
@@ -20,7 +20,7 @@ import { useFrecency } from "./frecency"
 import { useBindings } from "../../keymap"
 import { Reference } from "@/reference/reference"
 import type { Config } from "@/config/config"
-import { displayCharAt, mentionTriggerIndex } from "@/cli/cmd/prompt-display"
+import { displayCharAt, displaySlice, mentionTriggerIndex } from "@/cli/cmd/prompt-display"
 
 function removeLineRange(input: string) {
   const hashIndex = input.lastIndexOf("#")
@@ -135,7 +135,7 @@ export function Autocomplete(props: {
     // Track props.value to make memo reactive to text changes
     props.value // <- there surely is a better way to do this, like making .input() reactive
 
-    return props.input().getTextRange(store.index + 1, props.input().cursorOffset)
+    return displaySlice(props.value, store.index + 1, props.input().cursorOffset)
   })
 
   // filter() reads reactive props.value plus non-reactive cursor/text state.
@@ -767,7 +767,7 @@ export function Autocomplete(props: {
             // Typed text before the trigger
             props.input().cursorOffset <= store.index ||
             // There is a space between the trigger and the cursor
-            props.input().getTextRange(store.index, props.input().cursorOffset).match(/\s/) ||
+            displaySlice(value, store.index, props.input().cursorOffset).match(/\s/) ||
             // "/<command>" is not the sole content
             (store.visible === "/" && value.match(/^\S+\s+\S+\s*$/))
           ) {
@@ -781,7 +781,7 @@ export function Autocomplete(props: {
         if (offset === 0) return
 
         // Check for "/" at position 0 - reopen slash commands
-        if (value.startsWith("/") && !value.slice(0, offset).match(/\s/)) {
+        if (value.startsWith("/") && !displaySlice(value, 0, offset).match(/\s/)) {
           show("/")
           setStore("index", 0)
           return
diff --git a/packages/opencode/test/cli/run/prompt.shared.test.ts b/packages/opencode/test/cli/run/prompt.shared.test.ts
index 299751eaa347..bd45f022c6b4 100644
--- a/packages/opencode/test/cli/run/prompt.shared.test.ts
+++ b/packages/opencode/test/cli/run/prompt.shared.test.ts
@@ -135,6 +135,18 @@ describe("run prompt shared", () => {
     expect(mentionTriggerIndex("中文 @src file")).toBeUndefined()
   })
 
+  test("keeps autocomplete slicing width-safe after CJK prefixes", () => {
+    const mention = "中文 @readme"
+    const mentionStart = mentionTriggerIndex(mention, Bun.stringWidth(mention))
+    expect(mentionStart).toBe(5)
+    expect(displaySlice(mention, mentionStart! + 1, Bun.stringWidth(mention))).toBe("readme")
+    expect(displaySlice(mention, mentionStart!, Bun.stringWidth(mention)).match(/\s/)).toBeNull()
+
+    const slash = "/修复 bug"
+    expect(displaySlice(slash, 0, Bun.stringWidth("/修复")).match(/\s/)).toBeNull()
+    expect(displaySlice(slash, 0, Bun.stringWidth(slash)).match(/\s/)).not.toBeNull()
+  })
+
   test("handles direct and leader-based variant cycling", () => {
     const keys = promptKeys(keybinds)