fix(tui): remove red coloring from code syntax highlighting

.changeset/tui-code-highlight-no-red.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Remove red coloring from syntax highlighting in code previews and markdown code blocks.

apps/kimi-code/src/tui/components/media/code-highlight.ts

@@ -7,6 +7,8 @@ import { extname } from 'node:path';
 
 import { highlight, supportsLanguage } from 'cli-highlight';
 
+import { codeHighlightTheme } from '#/tui/theme/highlight-theme';
+
 const EXT_LANG_MAP: Record<string, string> = {
   ts: 'typescript',
   tsx: 'typescript',
@@ -45,7 +47,7 @@ export function highlightLines(code: string, lang: string | undefined): string[]
   const normalizedLang = lang?.trim().toLowerCase();
   if (!normalizedLang || !supportsLanguage(normalizedLang)) return code.split('\n');
   try {
-    return highlight(code, { language: normalizedLang, ignoreIllegals: true }).split('\n');
+    return highlight(code, { language: normalizedLang, ignoreIllegals: true, theme: codeHighlightTheme }).split('\n');
   } catch {
     return code.split('\n');
   }

apps/kimi-code/src/tui/theme/highlight-theme.ts

@@ -0,0 +1,17 @@
+/**
+ * Shared cli-highlight theme for code previews (Write/Edit tool calls,
+ * approval panels) and markdown code blocks.
+ *
+ * cli-highlight's DEFAULT_THEME paints `string`, `regexp` and `deletion`
+ * tokens red; reset exactly those tokens to `plain` so highlighted code
+ * contains no red at all. Tokens not listed here fall back to DEFAULT_THEME.
+ */
+
+import { plain } from 'cli-highlight';
+import type { Theme } from 'cli-highlight';
+
+export const codeHighlightTheme: Theme = {
+  string: plain,
+  regexp: plain,
+  deletion: plain,
+};

apps/kimi-code/src/tui/theme/pi-tui-theme.ts

@@ -13,6 +13,7 @@ import chalk from 'chalk';
 import { highlight, supportsLanguage } from 'cli-highlight';
 
 import { currentTheme } from './theme';
+import { codeHighlightTheme } from './highlight-theme';
 
 // pi-tui's renderer emits literal "### " / "#### " / ... markers for h3-h6
 // headings (h1/h2 are rendered without the `#` prefix). The prefix arrives
@@ -51,7 +52,7 @@ export function createMarkdownTheme(options?: { transient?: boolean }): Markdown
       const language =
         normalizedLang !== undefined && supportsLanguage(normalizedLang) ? normalizedLang : 'text';
       try {
-        const highlighted = highlight(code, { language, ignoreIllegals: true });
+        const highlighted = highlight(code, { language, ignoreIllegals: true, theme: codeHighlightTheme });
         return highlighted.split('\n');
       } catch {
         return code.split('\n');

apps/kimi-code/test/tui/components/media/code-highlight.test.ts

@@ -1,9 +1,15 @@
+import { createRequire } from 'node:module';
+import { dirname } from 'node:path';
+
 import { describe, expect, it } from 'vitest';
 
 import { highlightLines, langFromPath } from '#/tui/components/media/code-highlight';
+import { codeHighlightTheme } from '#/tui/theme/highlight-theme';
 
 import { captureProcessWrite } from '../../../helpers/process';
 
+const ESC = String.fromCodePoint(27);
+
 describe('code-highlight', () => {
   it('maps known file extensions to supported highlight languages', () => {
     expect(langFromPath('src/foo.ts')).toBe('typescript');
@@ -23,4 +29,32 @@ describe('code-highlight', () => {
       stderr.restore();
     }
   });
+
+  it('resets red tokens to plain styling', () => {
+    for (const token of ['string', 'regexp', 'deletion'] as const) {
+      expect(codeHighlightTheme[token]?.('code')).toBe('code');
+    }
+  });
+
+  it('emits no red SGR for strings, regexps and diff deletions', () => {
+    // cli-highlight styles through its own chalk v4 instance; force colors on
+    // so the assertions below observe real SGR sequences.
+    const req = createRequire(import.meta.url);
+    const chalkV4 = req(
+      req.resolve('chalk', { paths: [dirname(req.resolve('cli-highlight'))] }),
+    ) as { level: number };
+    const prevLevel = chalkV4.level;
+    chalkV4.level = 1;
+    try {
+      const js = highlightLines("const s = 'str';\nconst r = /re+/g;", 'javascript').join('\n');
+      expect(js).not.toContain(`${ESC}[31m`);
+      expect(js).toContain(`${ESC}[34m`); // keywords stay highlighted
+
+      const diff = highlightLines('+ added\n- removed', 'diff').join('\n');
+      expect(diff).not.toContain(`${ESC}[31m`);
+      expect(diff).toContain(`${ESC}[32m`); // additions stay green
+    } finally {
+      chalkV4.level = prevLevel;
+    }
+  });
 });