tray: Tray.placeSig analogue of placeCard for SIG SELECT exit; rename arc-in → fade-in — TDD

After all 3 gamers in a polarity room confirm TAKE SIG and the 12s countdown
expires, sig-select.js's room:polarity_room_done handler now plays the same
tray-open / fade-in / tray-close sequence the role-select uses, then
dismisses the sig overlay & shows the waiting msg ("Gravity settling…" /
"Levity appraising…") on Tray.placeSig's completion callback. Visual order:
sig stage → tray slides in → sig fades into the second tray cell → tray
slides out → table hex w. waiting msg. Cross-polarity events (other room
finishing while we're still in our overlay) are no-op as before.

- tray.js: new Tray.placeSig(sourceEl, onComplete). Mutates the SECOND
  .tray-cell in place (sig slot), copies aria-label / data-energies /
  data-operations / corner-rank + suit-icon markup from the source
  .sig-stage-card, then runs the shared open → fade-in → close sequence.
  Extracted _runFadeInSequence helper so placeCard + placeSig share the
  same animation glue. reset() now also clears .tray-sig-card from cells.

- _tray.scss: .tray-sig-card.fade-in > .sig-stage-card animates via the
  existing tray-role-fade-in keyframes.

- sig-select.js polarity_room_done handler: Tray.placeSig(stageCard,
  _settle); _settle runs the existing _dismissSigOverlay + _showWaitingMsg.
  Falls back to immediate dismiss when Tray is undefined (test environments
  without the tray).

- arc-in → fade-in rename across tray.js, role-select.js, _tray.scss
  (incl. @keyframes tray-role-arc-in → tray-role-fade-in), TraySpec.js
  spec descriptions + assertions, & test_room_role_select.py docstrings.
  The original "arc-in" name suggested a curved-path animation; the actual
  behaviour is a 1s opacity fade, so fade-in is the accurate label.

- TraySpec: 10 new placeSig specs mirroring placeCard (second-cell mutation,
  data + markup copy, tabIndex, fade-in class, animationend-triggered close,
  onComplete callback, landscape parity, reset cleanup).

- SigSelectSpec: 3 new specs (Tray.placeSig called w. stageCard on own
  polarity; not called on other polarity; overlay dismiss deferred to the
  Tray.placeSig completion callback).

344 specs / 4 pending green; RoleSelectTrayTest FT still green.

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/static/tests/SigSelectSpec.js

@@ -809,4 +809,63 @@ describe("SigSelect", () => {
             expect(takeSigBtn.classList.contains("btn-cancel")).toBe(false);
         });
     });
+
+    // ── polarity_room_done → tray sequence ─────────────────────────────────── //
+    //
+    // After all 3 gamers in the user's polarity confirm TAKE SIG and the
+    // 12s countdown expires, the server fires room:polarity_room_done. The
+    // sig-select handler should: (1) play the tray sequence — Tray.placeSig
+    // with the user's selected stage card; (2) on Tray.placeSig's completion
+    // callback, dismiss the overlay and show the waiting message. Tray runs
+    // FIRST, while the overlay is still up, so the slide is visually anchored
+    // to the sig stage's exit.
+    //
+    // Cross-polarity events (the OTHER room finishing while we're still
+    // selecting) must NOT trigger the sequence.
+
+    describe("polarity_room_done → tray sequence", () => {
+        beforeEach(() => {
+            // .table-center is appended to by _showWaitingMsg in the dismiss
+            // path; provide one so dismissal doesn't error.
+            const center = document.createElement("div");
+            center.className = "table-center";
+            document.body.appendChild(center);
+            makeFixture({ polarity: "levity", userRole: "PC" });
+            spyOn(Tray, "placeSig");
+        });
+
+        afterEach(() => {
+            document.querySelectorAll(".table-center, #id_hex_waiting_msg")
+                .forEach((el) => el.remove());
+        });
+
+        it("calls Tray.placeSig with the stage card when own polarity finishes", () => {
+            window.dispatchEvent(new CustomEvent("room:polarity_room_done", {
+                detail: { polarity: "levity" },
+            }));
+            expect(Tray.placeSig).toHaveBeenCalled();
+            const arg = Tray.placeSig.calls.mostRecent().args[0];
+            expect(arg).toBe(stageCard);
+        });
+
+        it("does NOT call Tray.placeSig when the OTHER polarity finishes", () => {
+            window.dispatchEvent(new CustomEvent("room:polarity_room_done", {
+                detail: { polarity: "gravity" },
+            }));
+            expect(Tray.placeSig).not.toHaveBeenCalled();
+        });
+
+        it("dismisses the overlay only AFTER Tray.placeSig's callback fires", () => {
+            window.dispatchEvent(new CustomEvent("room:polarity_room_done", {
+                detail: { polarity: "levity" },
+            }));
+            // Overlay still mounted — dismissal deferred to tray callback.
+            expect(document.querySelector(".sig-overlay")).not.toBe(null);
+
+            const cb = Tray.placeSig.calls.mostRecent().args[1];
+            cb();
+            expect(document.querySelector(".sig-overlay")).toBe(null);
+            expect(document.getElementById("id_hex_waiting_msg")).not.toBe(null);
+        });
+    });
 });