fix: preserve inline diff scroll range after content changes

packages/diff-view/src/parts/ApplyEditInput/ApplyEditInput.ts

@@ -29,7 +29,7 @@ export const applyEditInput = async (state: DiffViewState, inputValue: string):
   const totalLineCountRight = getLineCount(contentRight)
   const canComputeInlineDiff = state.renderModeLeft === 'text' && !state.errorLeftMessage
   const { inlineChanges, totalLineCount } = canComputeInlineDiff
-    ? await getInlineDiffState(state.contentLeft, contentRight)
+    ? await getInlineDiffState(state.contentLeft, contentRight, state.diffMode)
     : {
         inlineChanges: [],
         totalLineCount: Math.max(totalLineCountLeft, totalLineCountRight),

packages/diff-view/src/parts/DeleteLeft/DeleteLeft.ts

@@ -42,7 +42,7 @@ export const deleteLeft = async (state: DiffViewState): Promise<DiffViewState> =
   const totalLineCountRight = getLineCount(contentRight)
   const canComputeInlineDiff = state.renderModeLeft === 'text' && !state.errorLeftMessage
   const { inlineChanges, totalLineCount } = canComputeInlineDiff
-    ? await getInlineDiffState(state.contentLeft, contentRight)
+    ? await getInlineDiffState(state.contentLeft, contentRight, state.diffMode)
     : {
         inlineChanges: [],
         totalLineCount: Math.max(totalLineCountLeft, totalLineCountRight),

packages/diff-view/src/parts/DeleteRight/DeleteRight.ts

@@ -42,7 +42,7 @@ export const deleteRight = async (state: DiffViewState): Promise<DiffViewState>
   const totalLineCountRight = getLineCount(contentRight)
   const canComputeInlineDiff = state.renderModeLeft === 'text' && !state.errorLeftMessage
   const { inlineChanges, totalLineCount } = canComputeInlineDiff
-    ? await getInlineDiffState(state.contentLeft, contentRight)
+    ? await getInlineDiffState(state.contentLeft, contentRight, state.diffMode)
     : {
         inlineChanges: [],
         totalLineCount: Math.max(totalLineCountLeft, totalLineCountRight),

packages/diff-view/src/parts/GetInlineDiffState/GetInlineDiffState.ts

@@ -1,16 +1,19 @@
+import type { DiffMode } from '../DiffViewState/DiffViewState.ts'
 import type { InlineDiffChange } from '../InlineDiffChange/InlineDiffChange.ts'
 import { getInlineDiffChanges } from '../GetInlineDiffChanges/GetInlineDiffChanges.ts'
+import { getInlineDiffRows } from '../GetInlineDiffRows/GetInlineDiffRows.ts'
 import { getVisibleInlineDiffRows } from '../GetVisibleInlineDiffRows/GetVisibleInlineDiffRows.ts'
 
 export const getInlineDiffState = async (
   contentLeft: string,
   contentRight: string,
+  diffMode: DiffMode,
 ): Promise<{ readonly inlineChanges: readonly InlineDiffChange[]; readonly totalLineCount: number }> => {
   const linesLeft = contentLeft ? contentLeft.split('\n') : ['']
   const linesRight = contentRight ? contentRight.split('\n') : ['']
   const inlineChanges = await getInlineDiffChanges(linesLeft, linesRight)
   return {
     inlineChanges,
-    totalLineCount: Math.max(getVisibleInlineDiffRows(inlineChanges).length, 1),
+    totalLineCount: diffMode === 'inline' ? getInlineDiffRows(contentLeft, contentRight).length : Math.max(getVisibleInlineDiffRows(inlineChanges).length, 1),
   }
 }

packages/diff-view/src/parts/ReloadContent/ReloadContent.ts

@@ -35,7 +35,7 @@ export const reloadContent = async (
   errorRightCodeFrame: string,
   errorRightStack: string,
 ): Promise<DiffViewState> => {
-  const { assetDir, height, itemHeight, knownImageExtensions, minimumSliderSize, minLineY, platform, uriLeft, uriRight } = state
+  const { assetDir, diffMode, height, itemHeight, knownImageExtensions, minimumSliderSize, minLineY, platform, uriLeft, uriRight } = state
   const renderModeLeft = getRenderMode(uriLeft, knownImageExtensions)
   const renderModeRight = getRenderMode(uriRight, knownImageExtensions)
   const displayedContentLeft = getDisplayedContent(contentLeft, errorLeftMessage, errorLeftCodeFrame, errorLeftStack)
@@ -45,7 +45,7 @@ export const reloadContent = async (
   const gutterWidthVariable = getGutterWidthVariable(Math.max(totalLineCountLeft, totalLineCountRight))
   const canComputeInlineDiff = renderModeLeft === 'text' && renderModeRight === 'text' && !errorLeftMessage && !errorRightMessage
   const { inlineChanges, totalLineCount } = canComputeInlineDiff
-    ? await getInlineDiffState(contentLeft, contentRight)
+    ? await getInlineDiffState(contentLeft, contentRight, diffMode)
     : {
         inlineChanges: [],
         totalLineCount: Math.max(totalLineCountLeft, totalLineCountRight),

packages/diff-view/test/GetInlineDiffState.test.ts

@@ -0,0 +1,25 @@
+import { expect, test } from '@jest/globals'
+import { DiffWorker } from '@lvce-editor/rpc-registry'
+import { getInlineDiffState } from '../src/parts/GetInlineDiffState/GetInlineDiffState.ts'
+
+test('inline replacements use separate display rows for the original and modified lines', async () => {
+  using mockRpc = DiffWorker.registerMockRpc({
+    'Diff.diffInline': async () => [
+      { leftIndex: 0, rightIndex: 0, type: 2 },
+      { leftIndex: 0, rightIndex: 0, type: 1 },
+    ],
+  })
+  const inline = await getInlineDiffState('old', 'new', 'inline')
+  const sideBySide = await getInlineDiffState('old', 'new', 'side-by-side')
+  expect(inline.totalLineCount).toBe(2)
+  expect(sideBySide.totalLineCount).toBe(1)
+  expect(mockRpc.invocations).toHaveLength(2)
+})
+
+test('inline scrolling includes conflict decoration rows', async () => {
+  using mockRpc = DiffWorker.registerMockRpc({ 'Diff.diffInline': async () => [] })
+  const content = '<<<<<<< HEAD\ncurrent\n=======\nincoming\n>>>>>>> branch'
+  const result = await getInlineDiffState(content, content, 'inline')
+  expect(result.totalLineCount).toBe(7)
+  expect(mockRpc.invocations).toHaveLength(1)
+})

packages/diff-view/test/LoadContent.test.ts

@@ -279,10 +279,10 @@ test('loadContent expands total line count for inline mode when replacements spl
     contentLeft: 'same\nbefore\nshared',
     contentRight: 'same\nafter\nshared',
     diffMode: 'inline',
-    finalDeltaY: 0,
+    finalDeltaY: 20,
     maxLineY: 3,
     minLineY: 0,
-    totalLineCount: 3,
+    totalLineCount: 4,
     visibleLinesLeft: [
       {
         lineNumber: 1,

packages/e2e/src/diff.inline-scroll-after-edit.ts

@@ -0,0 +1,21 @@
+import type { Test } from '@lvce-editor/test-with-playwright'
+
+export const name = 'diff.inline-scroll-after-edit'
+
+export const test: Test = async ({ Command, DiffView, expect, FileSystem, Locator, Workspace }) => {
+  const tmpDir = await FileSystem.getTmpDir()
+  const before = Array.from({ length: 120 }, (_, index) => `old line ${index}`).join('\n')
+  const after = Array.from({ length: 120 }, (_, index) => `new line ${index}`).join('\n')
+  await FileSystem.writeFile(`${tmpDir}/before.txt`, before)
+  await FileSystem.writeFile(`${tmpDir}/after.txt`, after)
+  await Workspace.setPath(tmpDir)
+  await DiffView.open(`${tmpDir}/before.txt`, `${tmpDir}/after.txt`)
+  await Command.execute('DiffView.setDiffMode', 'inline')
+  await Command.execute('DiffView.setCursorPosition', 0, 0)
+  await Command.execute('DiffView.insertLineBreak')
+
+  const rows = Locator('.InlineDiffEditor .DiffEditorRows')
+  await rows.dispatchEvent('wheel', { bubbles: true, deltaMode: 0, deltaY: 9_999_999 } as unknown as string)
+  await expect(rows).toContainText('- old line 119')
+  await expect(rows).toContainText('+ new line 119')
+}