fix(editor): 新建文档自动聚焦 + 空文档占位 + 编辑面填满（docs/23）

新建/打开/恢复的标签就绪后自动把光标送进编辑器（弹窗/查找栏打开时
不抢）；切回标签恢复锚点时一并聚焦。空文档首段显示「开始输入…」
占位。编辑面改为撑满窗格高度，下方空白处可点击落光标；host 显式
width:100% 防 flex 收缩窄缝。

src/App.tsx

@@ -124,6 +124,15 @@ export default function App() {
   const editorRef = useRef<Editor | null>(null)
   const jumpRef = useRef<(text: string) => void>(() => undefined)
   const anchorApiRef = useRef<{ getAnchor: () => CursorAnchor | null; setCursorByAnchor: (a: CursorAnchor) => void } | null>(null)
+  // 刚新建/刚打开的标签：其编辑器就绪后应自动获得光标（新建文档进来没有光标是缺陷）。
+  const freshFocusRef = useRef<Set<string>>(new Set())
+  const findOpenRef = useRef(false)
+  /** 把键盘焦点送进编辑器；弹窗或查找栏打开时不抢焦点 */
+  const maybeFocusEditor = (editor: Editor | null | undefined) => {
+    if (!editor) return
+    if (anyModalRef.current || findOpenRef.current) return
+    focusEditor(editor)
+  }
   const sourceApiRef = useRef<SourceEditorApi | null>(null)
   const sourceModeRef = useRef(sourceMode)
   sourceModeRef.current = sourceMode
@@ -256,6 +265,7 @@ export default function App() {
         encoding: file.encoding, lineEnding: file.lineEnding, hadBom: file.hadBom,
       })
       const existing = stateRef.current.tabs.find((t) => samePath(t.path, path))
+      if (!existing) freshFocusRef.current.add(created.id)
       dispatch({ type: 'open', tab: created })
       const stat = await statFile(path)
       if (stat.exists) baselinesRef.current.set(existing?.id ?? created.id, { mtimeMs: stat.mtimeMs, size: stat.size })
@@ -264,7 +274,9 @@ export default function App() {
   }, [pushRecent])
 
   const newDoc = useCallback(() => {
-    dispatch({ type: 'open', tab: createTab({ title: '未命名', content: '' }) })
+    const created = createTab({ title: '未命名', content: '' })
+    freshFocusRef.current.add(created.id)
+    dispatch({ type: 'open', tab: created })
     setSourceMode(false)
   }, [])
 
@@ -275,7 +287,9 @@ export default function App() {
     } else {
       const picked = await pickAndReadWebFile()
       if (picked) {
-        dispatch({ type: 'open', tab: createTab({ title: picked.name.replace(/\.(md|markdown|txt)$/i, ''), content: picked.content }) })
+        const created = createTab({ title: picked.name.replace(/\.(md|markdown|txt)$/i, ''), content: picked.content })
+        freshFocusRef.current.add(created.id)
+        dispatch({ type: 'open', tab: created })
       }
     }
   }, [tauriMode, openPath])
@@ -447,6 +461,7 @@ export default function App() {
           encoding: file.encoding, lineEnding: file.lineEnding, hadBom: file.hadBom,
         })
         const existing = stateRef.current.tabs.find((t) => samePath(t.path, item.path))
+        if (!existing) freshFocusRef.current.add(created.id)
         dispatch({ type: 'open', tab: created })
         const targetId = existing?.id ?? created.id
         dispatch({ type: 'updateContent', id: targetId, content: item.content })
@@ -457,6 +472,7 @@ export default function App() {
       } catch { /* 文件已不存在时按未命名草稿恢复 */ }
     }
     const created = createTab({ title: item.title, content: '' })
+    freshFocusRef.current.add(created.id)
     dispatch({ type: 'open', tab: created })
     dispatch({ type: 'updateContent', id: created.id, content: item.content })
     finish()
@@ -834,9 +850,13 @@ export default function App() {
     editorRef.current = api?.editor ?? null
     jumpRef.current = api?.jumpToHeading ?? (() => undefined)
     anchorApiRef.current = api ? { getAnchor: api.getAnchor, setCursorByAnchor: api.setCursorByAnchor } : null
-    if (api && pendingAnchorRef.current) {
-      api.setCursorByAnchor(pendingAnchorRef.current)
-      pendingAnchorRef.current = null
+    if (api) {
+      const hadAnchor = Boolean(pendingAnchorRef.current)
+      if (hadAnchor) {
+        api.setCursorByAnchor(pendingAnchorRef.current as CursorAnchor)
+        pendingAnchorRef.current = null
+      }
+      if (hadAnchor || (activeIdForAlive && freshFocusRef.current.delete(activeIdForAlive))) maybeFocusEditor(api.editor)
     }
   }, [activeIdForAlive])
 
@@ -1071,6 +1091,7 @@ export default function App() {
     modal || appearanceOpen || exportOpen || pendingClose || conflict
     || promptSpec || confirmSpec || quitOpen || (recoveryOffer.length > 0 && !recoveryDismissed),
   )
+  findOpenRef.current = findUi.open
 
   // 大纲与状态栏计数只随正文变化重算（原先每次光标移动/击键都对全文重算）；
   // 大纲再经 useDeferredValue 让高频输入时延后提取，不堵击键路径。
@@ -1298,9 +1319,13 @@ export default function App() {
                   editorRef.current = api.editor
                   jumpRef.current = api.jumpToHeading
                   anchorApiRef.current = api.editor ? { getAnchor: api.getAnchor, setCursorByAnchor: api.setCursorByAnchor } : null
-                  if (api.editor && pendingAnchorRef.current) {
-                    api.setCursorByAnchor(pendingAnchorRef.current)
-                    pendingAnchorRef.current = null
+                  if (api.editor) {
+                    const hadAnchor = Boolean(pendingAnchorRef.current)
+                    if (hadAnchor) {
+                      api.setCursorByAnchor(pendingAnchorRef.current as CursorAnchor)
+                      pendingAnchorRef.current = null
+                    }
+                    if (hadAnchor || freshFocusRef.current.delete(t.id)) maybeFocusEditor(api.editor)
                   }
                 }}
               />

src/editor/editor.ts

@@ -12,7 +12,7 @@ import { clipboard } from '@milkdown/kit/plugin/clipboard'
 import { indent } from '@milkdown/kit/plugin/indent'
 import { math } from '@milkdown/plugin-math'
 import { upload, uploadConfig, type UploadOptions } from '@milkdown/kit/plugin/upload'
-import { createSyntaxRevealPlugin, createCodeBlockTabPlugin, createTableTabPlugin, createFocusDimPlugin, createPlainTextPastePlugin, createImageDisplayPlugin, selectionInTable } from './plugins'
+import { createSyntaxRevealPlugin, createCodeBlockTabPlugin, createTableTabPlugin, createFocusDimPlugin, createPlainTextPastePlugin, createImageDisplayPlugin, createEmptyPlaceholderPlugin, selectionInTable } from './plugins'
 import { createListItemViewPlugin, createCodeBlockViewPlugin } from './nodeViews'
 
 export interface CursorInfo { line: number; col: number }
@@ -90,6 +90,7 @@ export function createMarkdownEditor(root: HTMLElement, initialMarkdown: string,
     .use(createCodeBlockTabPlugin())
     .use(createTableTabPlugin())
     .use(createFocusDimPlugin())
+    .use(createEmptyPlaceholderPlugin())
     .use(createListItemViewPlugin())
     .use(createCodeBlockViewPlugin())
     .use(math)

src/editor/plugins.ts

@@ -210,6 +210,24 @@ export function isFocusModeEnabled() {
 }
 
 const focusKey = new PluginKey('new-markdown-focus')
+const emptyPlaceholderKey = new PluginKey('new-markdown-empty-placeholder')
+
+/** 空文档占位：整篇只有一段空段落时给它挂占位类，CSS ::before 显示「开始输入…」，
+ * 让新建文档有一个明确的输入界面（否则空页里连光标落点都看不见）。 */
+export function createEmptyPlaceholderPlugin() {
+  return $prose(() => new Plugin({
+    key: emptyPlaceholderKey,
+    props: {
+      decorations: (state) => {
+        const { doc } = state
+        if (doc.childCount !== 1) return DecorationSet.empty
+        const first = doc.firstChild
+        if (!first || first.type.name !== 'paragraph' || first.content.size !== 0) return DecorationSet.empty
+        return DecorationSet.create(doc, [Decoration.node(0, first.nodeSize, { class: 'doc-placeholder' })])
+      },
+    },
+  }))
+}
 
 interface FocusState {
   set: DecorationSet

src/styles.css

@@ -182,7 +182,15 @@ kbd { background: var(--code-bg); border: 1px solid var(--border); border-radius
 .milkdown .ProseMirror li.task-item { list-style: none; display: flex; align-items: flex-start; gap: 2px; margin-left: -1.1em; }
 .milkdown .ProseMirror .task-checkbox { margin-top: 0.42em; width: 15px; height: 15px; accent-color: var(--accent); cursor: pointer; flex: none; }
 .milkdown .ProseMirror li[data-checked='true'] .task-content { color: var(--text-dim); }
-.editor-pane-wrap { position: relative; min-height: 100%; }
+.editor-pane-wrap { position: relative; min-height: 100%; display: flex; flex-direction: column; align-items: center; }
+/* 编辑面填满窗格高度：空文档/短文档时下方大片区域也是可点击的输入面，
+   点任意处光标都会落进文档（原先只有内容实际占的那一条能点）。
+   host 必须显式 width:100%：flex 列里 margin:auto 会让它按内容收缩，
+   空文档时整列会缩成一条窄缝（实测踩过）。 */
+.editor-host { flex: 1; width: 100%; display: flex; flex-direction: column; }
+.editor-host .milkdown { flex: 1; display: flex; flex-direction: column; }
+.milkdown .ProseMirror { flex: 1; }
+.milkdown .ProseMirror .doc-placeholder::before { content: '开始输入…'; float: left; height: 0; pointer-events: none; color: color-mix(in srgb, var(--doc-ink, #24292f) 38%, transparent); }
 .table-toolbar { position: absolute; z-index: 30; display: flex; gap: 2px; align-items: center; background: var(--bg-editor); border: 1px solid var(--border); border-radius: 8px; padding: 3px; box-shadow: 0 6px 18px rgba(0,0,0,0.12); }
 .table-toolbar button { border: 0; background: transparent; padding: 4px 8px; border-radius: 6px; cursor: pointer; font-size: 12.5px; white-space: nowrap; }
 .table-toolbar button:hover { background: var(--accent-weak); }