fix(ui): heal incomplete backticks in streaming text rendering

packages/ui/src/components/markdown-stream.test.ts

@@ -20,6 +20,20 @@ describe("markdown stream", () => {
     ])
   })
 
+  test("heals incomplete backticks in trailing code fence tail", () => {
+    expect(stream("summary\n\n```sh\nrm -rf `", true)).toEqual([
+      { raw: "summary\n\n", src: "summary\n\n", mode: "live" },
+      { raw: "```sh\nrm -rf `", src: "```sh\nrm -rf ``", mode: "live" },
+    ])
+  })
+
+  test("handles backtick-heavy content that ends without trailing newline", () => {
+    const input = "run `git status` and `git"
+    const result = stream(input, true)
+    expect(result[0].raw).toBe(input)
+    expect(result[0].src).toContain("git status")
+  })
+
   test("keeps reference-style markdown as one block", () => {
     expect(stream("[docs][1]\n\n[1]: https://example.com", true)).toEqual([
       {

packages/ui/src/components/markdown-stream.ts

@@ -44,6 +44,6 @@ export function stream(text: string, live: boolean) {
   if (!head) return [{ raw: code.raw, src: code.raw, mode: "live" }] satisfies Block[]
   return [
     { raw: head, src: heal(head), mode: "live" },
-    { raw: code.raw, src: code.raw, mode: "live" },
+    { raw: code.raw, src: heal(code.raw), mode: "live" },
   ] satisfies Block[]
 }

packages/ui/src/components/message-part.tsx

@@ -188,7 +188,7 @@ export type PartComponent = Component<MessagePartProps>
 export const PART_MAPPING: Record<string, PartComponent | undefined> = {}
 
 const TEXT_RENDER_PACE_MS = 24
-const TEXT_RENDER_SNAP = /[\s.,!?;:)\]]/
+const TEXT_RENDER_SNAP = /[\s.,!?;:)\]\`]/
 
 function step(size: number) {
   if (size <= 12) return 2