feat(collab): cross-app selection — eeschema symbol ⇄ pcbnew footprint ghost highlight (collab-presence 0006)

Selecting a symbol in eeschema ghost-highlights the linked footprint(s) in
every pcbnew tab of the project, and vice versa — across users AND one
user's own two tabs. Native KIWAY cross-probe is inert in WASM (one frame
per page); this rides the presence layer instead.

- cross-app.ts: project-wide awareness-only room (presenceRoomId), publishes
  full PresenceState at selection rate (cursor always null); peers() = other-
  TOOL clients incl. own user's other tabs; window.__pcbjamCrossApp test handle
- presence-kicad.ts: parseSelectionEmit (bare array | {uuids,fpPaths}),
  xselFromPeerState (pcbnew paths → symbol uuids; eeschema uuids verbatim),
  cross peers appended to the kicadCollabSetRemote snapshot as
  {id "<user>#x<client>", name "<user> · sch|pcb", xsel}
- C++ (zero fork changes): pcbnew emits {uuids, fpPaths} (FOOTPRINT::GetPath)
  and ghost-renders xsel via path-tail suffix scan; eeschema resolves xsel via
  ResolveItem gated to the CURRENT sheet (xsel arrives project-wide, unlike
  room-scoped selections); ghostStyle = alphas × xselAlphaScale (0.55, tuner-
  patchable); new exports kicadCollabGetSelectionFull / TestGetCrossMapped /
  TestSelectComponent (skips power symbols — PWR_FLAG has no footprint) +
  merged-image dispatch
- tests: presence suites extended (payload shape, ghost render pixel tests,
  13/13) + new two-tab tests/web/cross-probe.spec.ts (passing vs real
  partykit); eeschema pixel compares now target the #glcanvas-* GAL panel
  (the whole-window #canvas compare flaked on the auto-dismissing version
  infobar — also fixes the long-known presence-eeschema restore flake);
  cross-app + presence-kicad vitest suites

Spec: docs/features/collab-presence/0006 (closed repo).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Lg5jwWuhFH5dL8hEcBDuP2

tests/web/cross-probe.spec.ts

@@ -0,0 +1,128 @@
+import { test, expect, type Page } from '@playwright/test';
+
+/**
+ * Cross-app selection e2e (collab-presence 0006): one tab on the demo
+ * SCHEMATIC and one on the demo BOARD of the same project share the
+ * project-wide presence room over the default BroadcastChannel provider.
+ * Selecting a symbol in eeschema must ghost-highlight the linked footprint in
+ * pcbnew (footprint `(path …)` tail = symbol uuid — the demo fixtures are
+ * linked), and vice versa. Assertions use the deterministic
+ * `kicadCollabTestGetCrossMapped()` probe (what the ghost render draws from)
+ * rather than pixel diffs — the render path itself is covered by the
+ * tests/kicad specs.
+ *
+ * This is also the single-user cross-probe test by construction: both tabs
+ * run as the same `?user=` in one browser context and still map each other
+ * (cross-app peers are keyed by client, not user).
+ */
+
+const SCOPE = 'default';
+
+type Mod = {
+  kicadCollabTestSelectComponent(): string;
+  kicadCollabTestClearSelection(): boolean;
+  kicadCollabTestGetCrossMapped(): string;
+  kicadCollabGetSelectionFull(): string;
+};
+type W = { Module: Mod };
+
+async function bootTool(
+  page: Page,
+  route: string,
+  titleRe: RegExp,
+  user: string,
+): Promise<void> {
+  await page.goto(`/${SCOPE}/projects/demo/${route}?user=${user}`);
+  await expect(page.locator('#canvas')).toBeVisible({ timeout: 120000 });
+  await expect
+    .poll(() => page.title(), {
+      message: `${route}: editor never reached the expected title`,
+      timeout: 120000,
+      intervals: [1000],
+    })
+    .toMatch(titleRe);
+  await page.waitForFunction(
+    () => {
+      const m = (window as unknown as Partial<W>).Module;
+      return (
+        typeof m?.kicadCollabTestSelectComponent === 'function' &&
+        typeof m?.kicadCollabTestGetCrossMapped === 'function'
+      );
+    },
+    null,
+    { timeout: 60000 },
+  );
+}
+
+const crossMapped = (page: Page) =>
+  page.evaluate(() =>
+    JSON.parse((window as unknown as W).Module.kicadCollabTestGetCrossMapped()),
+  );
+
+test('selecting a symbol in eeschema ghost-highlights the footprint in pcbnew, and back', async ({
+  page,
+  context,
+}) => {
+  test.setTimeout(480000); // two full editor boots (eeschema + pcbnew wasm)
+
+  const sch = page;
+  await bootTool(sch, 'demo.kicad_sch', /demo — Schematic Editor/i, 'alice');
+  const pcb = await context.newPage();
+  await bootTool(pcb, 'demo.kicad_pcb', /demo — PCB Editor/i, 'bob');
+
+  // ── eeschema → pcbnew ──────────────────────────────────────────────────────
+  const symId = await sch.evaluate(() =>
+    (window as unknown as W).Module.kicadCollabTestSelectComponent(),
+  );
+  expect(symId, 'demo schematic should contain a symbol').toBeTruthy();
+
+  // The board tab maps the symbol to ≥1 footprint (reused sheets map to more).
+  await expect
+    .poll(() => crossMapped(pcb), {
+      timeout: 20000,
+      message: 'pcbnew never received/mapped the eeschema selection',
+    })
+    .not.toEqual([]);
+
+  // The selection emit carried the symbol uuid across (sanity on the wire).
+  const schSel = await sch.evaluate(() =>
+    JSON.parse((window as unknown as W).Module.kicadCollabGetSelectionFull()),
+  );
+  expect(schSel.uuids).toContain(symId);
+
+  // Clearing the schematic selection clears the board ghosts.
+  await sch.evaluate(() =>
+    (window as unknown as W).Module.kicadCollabTestClearSelection(),
+  );
+  await expect
+    .poll(() => crossMapped(pcb), { timeout: 20000 })
+    .toEqual([]);
+
+  // ── pcbnew → eeschema ──────────────────────────────────────────────────────
+  const fpId = await pcb.evaluate(() =>
+    (window as unknown as W).Module.kicadCollabTestSelectComponent(),
+  );
+  expect(fpId, 'demo board should contain a footprint').toBeTruthy();
+
+  // The footprint's path tail resolves to a symbol on the schematic's sheet.
+  await expect
+    .poll(() => crossMapped(sch), {
+      timeout: 20000,
+      message: 'eeschema never received/mapped the pcbnew selection',
+    })
+    .not.toEqual([]);
+
+  // …and the emit carried the footprint's schematic path.
+  const pcbSel = await pcb.evaluate(() =>
+    JSON.parse((window as unknown as W).Module.kicadCollabGetSelectionFull()),
+  );
+  expect(pcbSel.uuids).toContain(fpId);
+  expect(pcbSel.fpPaths.length).toBeGreaterThan(0);
+
+  await pcb.evaluate(() =>
+    (window as unknown as W).Module.kicadCollabTestClearSelection(),
+  );
+  await expect
+    .poll(() => crossMapped(sch), { timeout: 20000 })
+    .toEqual([]);
+});