From 6f06a61aa8448ee961cf37a93bb0413a86ce3d9f Mon Sep 17 00:00:00 2001
From: LukeParkerDev <10430890+Hona@users.noreply.github.com>
Date: Sun, 14 Jun 2026 20:49:53 +0200
Subject: [PATCH] fix(ui): avoid blank streamed code line

---
 packages/ui/src/components/markdown-stream.test.ts | 12 ++++++++++++
 packages/ui/src/components/markdown-stream.ts      |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/packages/ui/src/components/markdown-stream.test.ts b/packages/ui/src/components/markdown-stream.test.ts
index 3ef9c0f3387..64a635b88d0 100644
--- a/packages/ui/src/components/markdown-stream.test.ts
+++ b/packages/ui/src/components/markdown-stream.test.ts
@@ -95,4 +95,16 @@ describe("markdown stream", () => {
       language: "ts",
     })
   })
+
+  test("does not add a blank line before the first streamed code", () => {
+    const previous = project(undefined, "```ts\n", true)
+    const next = project(previous, `${previous.text}const x = 1`, true)
+
+    expect(next.blocks.at(-1)).toEqual({
+      raw: "```ts\nconst x = 1",
+      src: "const x = 1",
+      mode: "code",
+      language: "ts",
+    })
+  })
 })
diff --git a/packages/ui/src/components/markdown-stream.ts b/packages/ui/src/components/markdown-stream.ts
index e260262c380..e1e22fe61a3 100644
--- a/packages/ui/src/components/markdown-stream.ts
+++ b/packages/ui/src/components/markdown-stream.ts
@@ -70,7 +70,7 @@ export function project(previous: Projection | undefined, text: string, live: bo
   const suffix = text.slice(previous.text.length)
   if (!suffix || tail?.mode !== "code" || tail.complete || suffix.includes("```") || suffix.includes("~~~"))
     return { text, blocks: stream(text, live) }
-  const separator = previous.text.endsWith("\n") && !tail.src.endsWith("\n") ? "\n" : ""
+  const separator = tail.src.length > 0 && previous.text.endsWith("\n") && !tail.src.endsWith("\n") ? "\n" : ""
   return {
     text,
     blocks: [