feat: align local-first workspace direction

Document the VSCode-like local-first product shape, demote Convex to a control-plane role, and retire stale architecture drafts.

Add local workspace migration/export references plus smoke coverage for no-Convex managed workspace startup, local markdown title/body/options persistence, asset upload behavior, and Convex fixture export.

Verification: git diff --cached --check; node scripts/check-local-first-convex-guard.js --staged; node scripts/task444-convex-workspace-export-local-fixture-smoke.js; node scripts/task166-local-first-managed-workspace-no-convex-smoke.js; node scripts/task167-local-markdown-title-body-options-no-convex-smoke.js

bugs/done/2026-05-18-p0-kernel-ai-bugfix-progress.md

@@ -59,6 +59,11 @@
 - `bugs/05-editor-mainline/done/5-16-sidebar-preferred-snapshot-query-overrides-live-stream-v1.md`
 - `bugs/05-editor-mainline/done/5-17-document-title-source-drift-live-sidebar-over-head-v1.md`
 - `bugs/05-editor-mainline/done/5-18-ai-write-body-does-not-sync-page-aggregate-content-v1.md`
+- `bugs/05-editor-mainline/done/5-19-page-aggregate-prefers-editor-document-v1.md`
+- `bugs/05-editor-mainline/done/5-20-page-body-save-strips-editor-document-before-convex-v1.md`
+- `bugs/05-editor-mainline/done/5-21-page-body-save-rejects-invalid-editor-document-v1.md`
+- `bugs/05-editor-mainline/done/5-22-documents-content-strips-editor-document-before-page-aggregate-v1.md`
+- `bugs/05-editor-mainline/done/5-23-editor-document-semantic-validation-v1.md`
 - `bugs/05-editor-mainline/done/5-9-c12-topbar-sidebar-toggle-noop-v1.md`
 
 收口结果：
@@ -66,6 +71,8 @@
 - Page Aggregate 标题、正文、页面设置、page tree、AI fetch 回读已经形成同一组可验证真相。
 - AI 外部写入后，文档 shell 会同步 Page Aggregate JSON script / session snapshot，避免下一次 AI context 继续读旧正文。
 - Sidebar preferred snapshot 与 live stream 的优先级漂移已从当前 P0 blocker 中移除。
+- Page Aggregate 读侧已从 route 主链保留 `editorDocument / blockDocument`，不再在 `documents.content.get` 结果中提前剥离原生块文档字段。
+- `editorDocument` 显式输入已补语义校验：必须带 `blocks`，且 `rootBlockIds` 必须引用真实块。
 
 关键证据：
 
@@ -92,6 +99,9 @@
 - `bugs/07-ai/done/7-28-markdown-edit-selection-scope-not-enforced-v1.md`
 - `bugs/07-ai/done/7-29-markdown-edit-flattens-inline-content-v1.md`
 - `bugs/07-ai/done/7-30-block-tools-selection-scope-not-enforced-v1.md`
+- `bugs/07-ai/done/7-31-page-ai-workflow-drops-read-summary-v1.md`
+- `bugs/07-ai/done/7-32-markdown-edit-page-body-save-missing-preconditions-v1.md`
+- `bugs/07-ai/done/7-33-markdown-edit-no-applied-operations-success-v1.md`
 
 收口结果：
 
@@ -105,6 +115,9 @@
 - `mnote.doc.markdown_edit` / `page_ai_workflow` 已补 selection scope 服务端兜底，`allowedTargetBlockIds` 外的写入会被拒绝。
 - `mnote.doc.markdown_edit` 写回普通块时不再无条件扁平化 inline content；未变更块保持原结构，单 inline text 节点的已变更块保留 marks / attrs。
 - 单个 `mnote.block.*` 写工具已补 selection scope 服务端兜底，越界块写入会返回 `mnote_block_target_out_of_scope`。
+- 页面 AI `block_edit_workflow` 现在会把模型 `summary` 返回给前端；“读取第一段 + 修改第二段”这类读写混合请求不再被固定写入文案吞掉读取结果。
+- 在线 `mnote.doc.markdown_edit` 直接 `page.body.save` 写回时已携带当前 `revision/conflictDetectionKey`。
+- `mnote.doc.markdown_edit` 全部 search 失败时返回 `mnote_markdown_edit_no_operations_applied`，不再误报成功或触发无意义保存。
 
 关键证据：