diff --git a/packages/client/ui-conversation/tests/read-card.spec.tsx b/packages/client/ui-conversation/tests/read-card.spec.tsx
index a4ead14748..d5804b505b 100644
--- a/packages/client/ui-conversation/tests/read-card.spec.tsx
+++ b/packages/client/ui-conversation/tests/read-card.spec.tsx
@@ -25,7 +25,11 @@ afterEach(cleanup)
 
 const SID = 's1' as SessionId
 
-const ARGS = '{"path":"src/a.ts","offset":41}'
+// The read tool's real schema key is `file_path`; the top-level read samples
+// use it so the row exercises a production-shaped call. `web_fetch` (below) has
+// its own schema whose key is not `file_path`, so it keeps a `url`-less `path`.
+const ARGS = '{"file_path":"src/a.ts","offset":41}'
+const WEB_FETCH_ARGS = '{"path":"src/a.ts","offset":41}'
 
 /** The read block's rendered content cells, one string per row (highlighting
  *  breaks a line across token spans, so match on the row's textContent). */
@@ -122,7 +126,7 @@ describe('GenericToolCard read body', () => {
     expect(CHAT_READ_MAX_LINES).toBeLessThan(16)
     // web_fetch lands on the read variant without its own keyed row, so the
     // fallback card owns the resident read block.
-    const view = render(<GenericToolCard {...ownerProps(settled({ call: { name: 'web_fetch', argsRaw: ARGS } }))} />)
+    const view = render(<GenericToolCard {...ownerProps(settled({ call: { name: 'web_fetch', argsRaw: WEB_FETCH_ARGS } }))} />)
     expect(view.container.querySelector('[data-read]')).not.toBeNull()
     expect(contentTexts(view.container)).toContain('export const a = 1')
     // The gutter keeps the file's own line numbers.
@@ -256,7 +260,7 @@ describe('DetailsPanel Output section (read)', () => {
     const view = mount(snapshot({
       nodes: [settled({ resultView: resultRead({ lines: long, totalLines: 20 }) })],
     }), target)
-    expect(view.getByText(/"path"/)).toBeTruthy()
+    expect(view.getByText(/"file_path"/)).toBeTruthy()
     expect(view.container.querySelector('[data-read]')).not.toBeNull()
     // The panel takes the primitive's own default cap (16), not the row's.
     expect(view.getByText(`… 其余 ${20 - 16} 行`)).toBeTruthy()
diff --git a/packages/client/ui-primitives/src/markdown/highlight.ts b/packages/client/ui-primitives/src/markdown/highlight.ts
index 2116fa2b93..d0727c833a 100644
--- a/packages/client/ui-primitives/src/markdown/highlight.ts
+++ b/packages/client/ui-primitives/src/markdown/highlight.ts
@@ -32,9 +32,12 @@ type LangModule = { default: typeof langTs }
 
 /**
  * Grammars the singleton loads at boot; each entry's own `name` is the id
- * `codeToTokens`/`codeToHtml` resolve. The TypeScript grammar embeds JS/JSX/TSX,
- * so the JS-family fence aliases resolve to it rather than a separate grammar.
- * The read card's wider set loads lazily through {@link LAZY_GRAMMARS}.
+ * `codeToTokens`/`codeToHtml` resolve. The JS-family aliases (js/jsx/ts/tsx)
+ * resolve to the TypeScript grammar rather than a separate one: it tokenizes
+ * plain TS/JS exactly, and JSX/TSX approximately (shiki's TS grammar is not the
+ * dedicated TSX grammar, so JSX elements tokenize imperfectly) — an accepted
+ * trade to keep the boot set to one JS-family grammar. The read card's wider
+ * set loads lazily through {@link LAZY_GRAMMARS}.
  */
 const LANGS = [langTs, langBash, langJson]
 
@@ -80,9 +83,10 @@ const LAZY_GRAMMARS = new Map<string, () => Promise<LangModule>>([
  * inherited property and crashing the renderer inside shiki. Keys cover both
  * the markdown-fence aliases `CodeBlock` uses and the file-extension hint ids
  * the read tool's `langFromPath` emits, so both callers resolve the same
- * grammars. The JS family maps to the TypeScript grammar (which embeds it),
- * unchanged from when this was the only non-shell/JSON grammar. A value not in
- * {@link LANGS} names a {@link LAZY_GRAMMARS} entry loaded on first use.
+ * grammars. The JS family maps to the TypeScript grammar (see {@link LANGS} for
+ * the JSX/TSX approximation), unchanged from when this was the only
+ * non-shell/JSON grammar. A value not in {@link LANGS} names a
+ * {@link LAZY_GRAMMARS} entry loaded on first use.
  */
 const LANG_ALIASES = new Map<string, string>([
   ['typescript', 'typescript'],