Seed the mouse editor from its target, and mark the target on the first edit (improvise-ugj4, improvise-jibp)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze

web/shell.js

@@ -222,7 +222,6 @@ export function gridPlan(model) {
           row: dataRow,
           col,
           text: typing ? `${model.editing}▏` : cell.text,
-          editText: cell.edit_text,
           editable: cell.editable,
           classes: {
             numeric: cell.numeric && !typing,
@@ -260,7 +259,7 @@ export function gridPlan(model) {
 /** What a data cell carries on its node, so one delegated handler can read
  *  back the answers `gridPlan` already made (improvise-b8ot, clients.md). */
 export function cellAttrs(cell) {
-  return { row: String(cell.row), col: String(cell.col), edit: cell.editText };
+  return { row: String(cell.row), col: String(cell.col) };
 }
 
 /** …and the inverse: what a delegated mousedown MEANS. `null` where the event
@@ -271,7 +270,7 @@ export function cellAction(dataset, editable) {
   // A node that carries no coordinates is not a cell: every header and the
   // corner reach here, and none of them means anything.
   if (row === null || col === null) return null;
-  return { row, col, editable, editText: dataset.edit ?? "" };
+  return { row, col, editable };
 }
 
 /** The same, for the surfaces whose rows are named by one index: the panels,