fix: show honest new-space display defaults

Issue: #204
User-Visible: yes

test/space-dialog.test.mjs

@@ -0,0 +1,62 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+
+import {
+  initialSpaceDisplayDraft,
+  switchSpacePlanSource,
+  touchSpaceDisplay,
+} from '../test-build/space-dialog.js';
+
+test('fresh create projects honest File and Draw display defaults', () => {
+  const file = initialSpaceDisplayDraft();
+  assert.deepEqual(file, {
+    source: 'file', showBorders: false, showNames: false, displayTouched: false,
+  });
+
+  const draw = switchSpacePlanSource(file, 'draw');
+  assert.deepEqual(draw, {
+    source: 'draw', showBorders: true, showNames: true, displayTouched: false,
+  });
+  assert.deepEqual(switchSpacePlanSource(draw, 'file'), file);
+});
+
+test('touching either display switch preserves the complete mixed pair', () => {
+  const draw = switchSpacePlanSource(initialSpaceDisplayDraft(), 'draw');
+  const mixed = touchSpaceDisplay(draw, 'showBorders', false);
+  assert.deepEqual(mixed, {
+    source: 'draw', showBorders: false, showNames: true, displayTouched: true,
+  });
+  assert.deepEqual(switchSpacePlanSource(mixed, 'file'), {
+    ...mixed, source: 'file',
+  });
+  assert.deepEqual(switchSpacePlanSource(mixed, 'draw'), mixed);
+});
+
+test('every supported Draw pair remains exact after a touched source round-trip', () => {
+  for (const [showBorders, showNames] of [
+    [false, false], [true, false], [false, true],
+  ]) {
+    let draft = switchSpacePlanSource(initialSpaceDisplayDraft(), 'draw');
+    draft = touchSpaceDisplay(draft, 'showBorders', showBorders);
+    draft = touchSpaceDisplay(draft, 'showNames', showNames);
+    const roundTrip = switchSpacePlanSource(switchSpacePlanSource(draft, 'file'), 'draw');
+    assert.deepEqual(roundTrip, {
+      source: 'draw', showBorders, showNames, displayTouched: true,
+    });
+  }
+});
+
+test('source and display transitions are immutable and preserve unrelated fields', () => {
+  const draft = { ...initialSpaceDisplayDraft(), title: 'Ground', cellCm: 7.5 };
+  const switched = switchSpacePlanSource(draft, 'draw');
+  const touched = touchSpaceDisplay(switched, 'showNames', false);
+
+  assert.notEqual(switched, draft);
+  assert.notEqual(touched, switched);
+  assert.deepEqual(draft, {
+    source: 'file', showBorders: false, showNames: false, displayTouched: false,
+    title: 'Ground', cellCm: 7.5,
+  });
+  assert.equal(touched.title, 'Ground');
+  assert.equal(touched.cellCm, 7.5);
+});