fix(tui): open @ file mentions inside slash command arguments (#1223)

Typing @ in the middle of a slash command argument (for example `/goal Fix the @checkout docs`) was swallowed by the slash-argument completion guard before the @ mention branch ran, so the file list never opened. Run the @ mention branch ahead of the slash guards so file mentions take priority; plain slash-argument editing is still suppressed as before.

.changeset/fix-at-mention-slash-arg.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Fix @ file mentions not opening when typed inside a slash command argument.

apps/kimi-code/src/tui/components/editor/file-mention-provider.ts

@@ -67,20 +67,11 @@ export class FileMentionProvider implements AutocompleteProvider {
     const currentLine = lines[cursorLine] ?? '';
     const textBeforeCursor = currentLine.slice(0, cursorCol);
 
-    if (shouldSuppressLeadingWhitespaceSlashPath(textBeforeCursor, options.force)) {
-      return null;
-    }
-
-    if (
-      shouldSuppressSlashArgumentCompletion(
-        textBeforeCursor,
-        currentLine.slice(cursorCol),
-        options.force,
-      )
-    ) {
-      return null;
-    }
-
+    // `@` file / folder mentions take priority over the slash-command guards
+    // below. Without this, typing `@` inside a slash command's argument text
+    // (e.g. `/goal Fix the @|checkout docs`) would be swallowed by
+    // `shouldSuppressSlashArgumentCompletion` before the mention branch ever
+    // runs, so the file list never opens.
     const atPrefix = extractAtPrefix(textBeforeCursor);
     if (atPrefix !== null) {
       if (this.fdPath === null || this.additionalDirs.length > 0) {
@@ -104,6 +95,20 @@ export class FileMentionProvider implements AutocompleteProvider {
       }
     }
 
+    if (shouldSuppressLeadingWhitespaceSlashPath(textBeforeCursor, options.force)) {
+      return null;
+    }
+
+    if (
+      shouldSuppressSlashArgumentCompletion(
+        textBeforeCursor,
+        currentLine.slice(cursorCol),
+        options.force,
+      )
+    ) {
+      return null;
+    }
+
     // Handle slash-command name completion ourselves so that aliases are
     // searchable and visible in the label.
     if (!options.force && textBeforeCursor.startsWith('/')) {

apps/kimi-code/test/tui/components/editor/file-mention-provider.test.ts

@@ -99,6 +99,21 @@ describe('FileMentionProvider', () => {
     expect(result).toBeNull();
   });
 
+  it('opens @ file mention when typed in the middle of a slash command argument', async () => {
+    writeFileSync(join(workDir, 'README.md'), 'readme');
+    const provider = new FileMentionProvider([GOAL_COMMAND], workDir, NO_FD);
+    // Cursor sits in the middle of the /goal argument text, right after a
+    // freshly typed `@`. The slash-argument guard must not suppress the @
+    // file list here.
+    const line = '/goal Fix the @checkout docs';
+    const result = await provider.getSuggestions([line], 0, '/goal Fix the @'.length, {
+      signal: ctrl(),
+    });
+    expect(result).not.toBeNull();
+    expect(result!.prefix).toBe('@');
+    expect(result!.items.map((item) => item.value)).toContain('@README.md');
+  });
+
   it('still completes slash arguments at the end of an empty argument', async () => {
     const provider = new FileMentionProvider([GOAL_COMMAND], workDir, NO_FD);
     const line = '/goal ';