Editor: cursor-scoped Add view and reorder for composition views

docs/architecture/08-vega-editor-techniques.md

@@ -296,7 +296,9 @@ thin app-layer services.
   cursor's ancestor chain (`derivedFieldNamesAtPath`).
 - `spec-inline-data` — the rows a specific `data` binding carries for profiling
   (`rowsForDataBinding`: inline `values`, or a self-defined `datasets` entry).
-- `spec-insert` — composition arrays + appending a view to one.
+- `spec-insert` — the composition the cursor is in (`compositionTargetAt`), inserting a view
+  at an index (`insertView`) and reordering siblings (`moveView`), plus `elementOffset` to
+  re-find a view after the edit.
 
 **Services (app, store-aware via `getState`):** `spec-transform-actions` (the
 wrap/simplify/add-view operations and their surfaces), `spec-dataset-hints` (completion,
@@ -318,6 +320,17 @@ Decision rules:
 - **One edit path.** The lightbulb returns a `WorkspaceEdit` (no editor handle); the toolbar
   and palette use `executeEdits`. Both build the replacement through the same
   serialize-and-reindent step, bracketed by `pushUndoStop`, so ⌘Z restores the prior text.
+- **Composition CodeLens is cursor-scoped.** It follows the view the cursor sits in —
+  `＋ Add view above/below` at the view's edges and `↑/↓ Move` to reorder among its siblings —
+  rather than one fixed button per composition array; an empty composition shows a single `＋ Add view`,
+  and the F1 palette mirrors all four for the keyboard. The provider reads `editor.getPosition()`
+  and refreshes via an `onDidChange` emitter fired on cursor moves (keyed to the enclosing view,
+  so typing inside one view doesn't churn the lenses). After an edit the cursor follows the
+  affected view (`elementOffset`), so a repeated click keeps acting on it instead of the
+  neighbour that slid into place. Cursor-scoping does not strand a load-bearing action
+  ([arch 10](10-interaction-and-feedback.md) — revealed actions): editing a composition puts
+  the cursor in a view exactly when add/reorder is wanted, and the palette is the ever-present
+  path for the keyboard.
 - **Field source for hints (view-scoped).** `dataInfoAt(text, offset)` resolves the data
   binding of the cursor's **nearest enclosing view** (`dataBindingAtPath` — a child inherits a
   parent's data unless it declares its own), then its columns: a named **library dataset**