fix(app): prompt input quirks

1 files changed, 31 insertions, 5 deletions

diff --git a/packages/app/src/components/prompt-input/editor-dom.test.ts b/packages/app/src/components/prompt-input/editor-dom.test.ts
index fce8b4b95..15e759f44 100644
--- a/packages/app/src/components/prompt-input/editor-dom.test.ts
+++ b/packages/app/src/components/prompt-input/editor-dom.test.ts
@@ -2,17 +2,26 @@ import { describe, expect, test } from "bun:test"
 import { createTextFragment, getCursorPosition, getNodeLength, getTextLength, setCursorPosition } from "./editor-dom"
 
 describe("prompt-input editor dom", () => {
-  test("createTextFragment preserves newlines with br and zero-width placeholders", () => {
+  test("createTextFragment preserves newlines with consecutive br nodes", () => {
     const fragment = createTextFragment("foo\n\nbar")
     const container = document.createElement("div")
     container.appendChild(fragment)
 
-    expect(container.childNodes.length).toBe(5)
+    expect(container.childNodes.length).toBe(4)
+    expect(container.childNodes[0]?.textContent).toBe("foo")
+    expect((container.childNodes[1] as HTMLElement).tagName).toBe("BR")
+    expect((container.childNodes[2] as HTMLElement).tagName).toBe("BR")
+    expect(container.childNodes[3]?.textContent).toBe("bar")
+  })
+
+  test("createTextFragment keeps trailing newline as terminal break", () => {
+    const fragment = createTextFragment("foo\n")
+    const container = document.createElement("div")
+    container.appendChild(fragment)
+
+    expect(container.childNodes.length).toBe(2)
     expect(container.childNodes[0]?.textContent).toBe("foo")
     expect((container.childNodes[1] as HTMLElement).tagName).toBe("BR")
-    expect(container.childNodes[2]?.textContent).toBe("\u200B")
-    expect((container.childNodes[3] as HTMLElement).tagName).toBe("BR")
-    expect(container.childNodes[4]?.textContent).toBe("bar")
   })
 
   test("length helpers treat breaks as one char and ignore zero-width chars", () => {
@@ -48,4 +57,21 @@ describe("prompt-input editor dom", () => {
 
     container.remove()
   })
+
+  test("setCursorPosition and getCursorPosition round-trip across blank lines", () => {
+    const container = document.createElement("div")
+    container.appendChild(document.createTextNode("a"))
+    container.appendChild(document.createElement("br"))
+    container.appendChild(document.createElement("br"))
+    container.appendChild(document.createTextNode("b"))
+    document.body.appendChild(container)
+
+    setCursorPosition(container, 2)
+    expect(getCursorPosition(container)).toBe(2)
+
+    setCursorPosition(container, 3)
+    expect(getCursorPosition(container)).toBe(3)
+
+    container.remove()
+  })
 })