Finish the struct and list leftovers: inline lists, list fields, item kinds

An unconnected list input is a button into the List tab instead of a number
field; a struct field can hold a list, so ListSlot carries an optional field
name and the three owner cases only say what sits at a key; and a list
variable picks its item kind in the inspector (marker doubles as the chooser),
so a list of structs no longer has to be born from a project file.

The declaration keeps the storable shapes finite: a struct field may be a list,
but that list holds primitives only, so list->struct->primitive and
struct->list->primitive are the two deepest forms.

check 674, e2e 483, jump-run 24, Tetris 19.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tools/e2e/21-list.mjs

@@ -95,6 +95,34 @@ export async function listTab(t) {
   await sleep(200);
   check('and the count follows the value', (await find('2 items')) !== null);
 
+  // 6b. What a list holds is a choice in the inspector, not only in a project file: the kind mark
+  //     doubles as the picker, and changing it runs every value through the new declaration.
+  const numsOf = () => json(`__gm.state.project.assets.find((a) => a.id === 'listy')`);
+  await clickText('\u2261#');
+  await sleep(150);
+  await clickText('Texts');
+  await sleep(250);
+  let listy = await numsOf();
+  check(
+    'the kind mark picks what the list holds',
+    listy.variables[0].items === 'text',
+    listy.variables[0].items,
+  );
+  check('and the mark itself says what it holds now', (await find('≡Aa')) !== null);
+  check(
+    'and every value follows the declaration',
+    JSON.stringify(listy.props.nums) === '["1","2"]',
+    JSON.stringify(listy.props.nums),
+  );
+  await undo();
+  await sleep(250);
+  listy = await numsOf();
+  check(
+    'undo puts the kind and the values back',
+    listy.variables[0].items === 'number' && JSON.stringify(listy.props.nums) === '[1,2]',
+    JSON.stringify(listy.props.nums),
+  );
+
   // 7. A list whose target is gone empties the tab rather than showing a stale one.
   await mutate("__gm.state.openList({ kind: 'asset', assetId: 'listy', key: 'nums' })");
   await sleep(200);
@@ -176,10 +204,73 @@ export async function listTab(t) {
     JSON.stringify(back),
   );
 
+  // 8b. The item shape is declared in the inspector as well, with the control a struct has – and
+  //     primitives only, because a list inside a list item is the one shape the model does not store.
+  const cellsOf = () => json(`__gm.state.project.assets.find((a) => a.id === 'celly').props.cells`);
+  check('a list of structs carries the add-a-field control', (await find('+ Field')) !== null);
+  await clickText('+ Field');
+  await sleep(150);
+  await clickText('Boolean');
+  await sleep(250);
+  check(
+    '+ Field grows every item of the list at once',
+    JSON.stringify(await cellsOf()) ===
+      JSON.stringify([
+        { x: 30, y: 11, field1: false },
+        { x: 44, y: 55, field1: false },
+      ]),
+    JSON.stringify(await cellsOf()),
+  );
+  info = await json('__gm.list.info()');
+  check(
+    'and the tab shows the new field on every row',
+    info.items[0] === 'x: 30, y: 11, field1: false',
+    info.items[0],
+  );
+  await shot('06-item-field');
+  await undo();
+  await sleep(250);
+  check(
+    'undo takes it out of every item again',
+    JSON.stringify(await cellsOf()) ===
+      JSON.stringify([
+        { x: 30, y: 11 },
+        { x: 44, y: 55 },
+      ]),
+    JSON.stringify(await cellsOf()),
+  );
+
+  // 9. A node's unconnected `list` input carries its value in the very same params bag a setting
+  //    does, so it is a count button too – before this it offered a number field.
+  await mutate(`
+    const a = __gm.state.project.assets.find((x) => x.id === 'celly');
+    a.graph.nodes.push({ id: 'counter', type: 'Count', x: 40, y: 40, params: {} });
+    __gm.showTab('graph');
+    __gm.state.select({ kind: 'node', assetId: 'celly', nodeId: 'counter', nodeIds: ['counter'] });
+    __gm.state.preview();
+  `);
+  await sleep(300);
+  const portButton = await find('0 items');
+  check('an unconnected list input reads as an item count', portButton !== null);
+  await click(portButton.x, portButton.y);
+  await sleep(250);
+  check('clicking it opens the List tab on the port', (await json('__gm.tab()')) === 'list');
+  info = await json('__gm.list.info()');
+  check('titled by the node and the port it belongs to', info.title === 'Count · list', info.title);
+  await clickText('+ Item');
+  await sleep(250);
+  const params = await json(`__gm.state.project.assets.find((a) => a.id === 'celly').graph.nodes[0].params`);
+  check(
+    'and the item lands in the node params, where the node reads it',
+    JSON.stringify(params) === '{"list":[0]}',
+    JSON.stringify(params),
+  );
+
   await mutate(`
     const p = __gm.state.project;
     p.assets = p.assets.filter((a) => a.id !== 'celly');
     __gm.state.select(null);
+    __gm.showTab('scene');
     __gm.state.preview();
   `);
   await sleep(200);