collab: repair duplicated layout header groups after seed and on remote layout merges (ysync 0011 follow-up; shared → f14401b)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0189z2siCsezE39ugcDKNBMs

web/standalone/src/wasm/collab/kicad-binding.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, it } from "vitest";
 import * as Y from "yjs";
 import {
   docToFile,
+  duplicateSingletonHeadIndices,
   fileToDoc,
   itemsWireToDelta,
   kicadLibSymbolsMap,
@@ -226,6 +227,32 @@ describe("bindKicadCollab — two editors over relayed Y.Docs", () => {
     expect(edB.store["r-1"]).toBeDefined();
   });
 
+  it("a layout-only write racing a file seed converges to ONE header block (no double version)", () => {
+    // Session 1 (old client) save-all wrote a layout-only doc; session 2 file-seeded
+    // BEFORE that state arrived. Merged, the layout carried the header twice and
+    // KiCad rejected the materialized sheet ("Expecting … Got version").
+    const { a, b, edA, edB, bindA, bindB } = setup();
+    const file = `(kicad_wks (version 20220228) (generator "pl_editor")
+  (setup (textsize 1.5 1.5) (linewidth 0.15))
+  (rect (uuid "r-1") (name "border") (start 0 0 ltcorner) (end 0 0 rbcorner))
+)
+`;
+    const seedDoc = fileToDoc(file);
+    // Hold the relay: build the two histories independently, then merge.
+    const hollow = new Y.Doc();
+    syncLayoutToY(seedDoc, hollow, "layout-save");
+    Object.assign(edA.store, seedDoc.items);
+    bindA.seed(seedDoc); // A file-seeds an (apparently) empty room
+    Y.applyUpdate(a, Y.encodeStateAsUpdate(hollow), "relay"); // the stale layout lands
+    const text = docToFile(yToDoc(a));
+    expect((text.match(/\(version /g) ?? []).length).toBe(1);
+    expect(text).toBe(docToFile(seedDoc));
+    // The doc itself was repaired (not just the render): B sees a single header.
+    expect(duplicateSingletonHeadIndices(yToDoc(b).layout)).toEqual([]);
+    bindB.seed();
+    expect(edB.store["r-1"]).toBeDefined();
+  });
+
   it("a seeded room that was legitimately emptied is still adopted (not mistaken for hollow)", () => {
     const { a, edA, edB, bindA, bindB } = setup();
     const file = `(kicad_wks (version 20220228) (generator "pl_editor")

web/standalone/src/wasm/collab/kicad-binding.ts

@@ -9,11 +9,13 @@ import {
   kicadItemsMap,
   kicadLibSymbolsMap,
   parseItemsWireDelta,
+  repairLayoutY,
   seedDocToY,
   SEXPR_VERSION_SUPPORTED,
   upsertLibSymbolsToY,
   wireItemUuids,
   wireLibSymbols,
+  Y_KDOC_LAYOUT,
   Y_KDOC_META,
   Y_KDOC_REVERT_AT,
   Y_KDOC_REVERT_NONCE,
@@ -235,6 +237,26 @@ export function bindKicadCollab(
   };
   items.observeDeep(observer);
 
+  // Layout convergence (ysync 0011 follow-up): a remote merge that lands a
+  // second copy of the header block (a layout-only save-sync racing a file
+  // seed) would materialize as a file KiCad refuses to load. Repair on every
+  // remote layout change and after seed(); peers delete the same entries, so
+  // the doc converges to one header. A viewer never writes.
+  const layout = doc.getArray(Y_KDOC_LAYOUT);
+  const repairLayout = (why: string): void => {
+    if (readOnly || destroyed) return;
+    try {
+      if (repairLayoutY(doc, ORIGIN)) clog(`layout repaired (duplicate header groups) — ${why}`);
+    } catch (err) {
+      cwarn("layout repair failed", err);
+    }
+  };
+  const onLayout = (_ev: unknown, txn: Y.Transaction) => {
+    if (txn.origin === ORIGIN) return;
+    repairLayout("remote layout change");
+  };
+  layout.observe(onLayout);
+
   // Validity-revert notice (kicad-validity 0001 B3): the backend stamps
   // kdoc_meta.revertNonce when it rolls the doc back to the last valid state
   // (the content itself arrives through the normal item sync above). Watched
@@ -261,6 +283,14 @@ export function bindKicadCollab(
   revMeta.observe(onRevertMeta);
 
   function seed(seedDoc?: KicadDoc, opts?: { editorMatchesDoc?: boolean }): void {
+    try {
+      seedInner(seedDoc, opts);
+    } finally {
+      repairLayout("post-seed");
+    }
+  }
+
+  function seedInner(seedDoc?: KicadDoc, opts?: { editorMatchesDoc?: boolean }): void {
     seeded = true; // open the UP gate; everything below runs synchronously
     // `ydocHasState` (meta + layout + items), NOT `items.size`: a populated
     // drawing sheet (pl_editor .kicad_wks) has zero uuid items, so an items-only
@@ -422,6 +452,7 @@ export function bindKicadCollab(
     seed,
     destroy: () => {
       destroyed = true; // gates the DOWN hook — see bug 07 note above
+      layout.unobserve(onLayout);
       detachSeedArbitration?.();
       detachSeedArbitration = undefined;
       items.unobserveDeep(observer);