feat(ysync): lib_symbols travel + layout save-sync (miss 08), TS hot-path opts (12), diff-on-rebind adopt (13) — doc 18

Miss 08A: the binding stores wire-carried (lib_symbols …) definitions in
kdoc_libsymbols and prefixes them on apply wires — a joiner that never saw a
symbol adopts it WITH its definition (new e2e ysync-libsymbols.spec.ts).
Miss 08B: registerSaveHook gains onSavedText; WasmTool routes saved-file text
to syncLayoutToY (per sheet room via the manager's syncLayoutFromSave, or the
single-room doc) so title block / paper / setup edits converge instead of
drifting. Opt 12 (TS half): zod off the observer hot path (yToItemUnchecked),
children index built once per conversion. Opt 13: seed()'s adopt diffs the
editor snapshot against the doc view and applies only the doc-authoritative
difference — clean rebinds apply nothing, the adopt undo entry shrinks to the
real changed set. Opt 14 deliberately deferred (doc 18). All TS-side; no wasm
rebuild (the C++ blob/findLib sides already carried definitions).

Verified: shared 107, standalone 79 (+2 known pre-existing wasm-assets),
ysync e2e 21/21 chromium, collab regression 21/3-skip firefox.

Bumps: web/pcbjam-shared (lib_symbols channel + syncLayoutToY + opts).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JgThWXtdvrYLK47EDFoGdq

docs/features/ysync-review/00-overview.md

@@ -93,3 +93,4 @@ sending half emits NOTHING, not the bare removal the doc predicted).
 | 15 | [15-plan-repro-tests-and-v2-e2e.md](15-plan-repro-tests-and-v2-e2e.md) | The approved plan: repro tests for bugs 01–07 + the v2 e2e port |
 | 16 | [16-repro-suite-results-and-empirical-findings.md](16-repro-suite-results-and-empirical-findings.md) | Plan 15 executed (2026-07-03): suite map, verified failure sites, empirical findings F1–F4 |
 | 17 | [17-fixes-bugs-01-07.md](17-fixes-bugs-01-07.md) | Bugs 01–07 fixed & verified (2026-07-03); findings F5–F6; remaining follow-ups |
+| 18 | [18-miss08-opts-12-13.md](18-miss08-opts-12-13.md) | Miss 08 (lib_symbols + layout save-sync) + opts 12/13 implemented; opt 14 deferred (2026-07-03) |

docs/features/ysync-review/08-miss-layout-state-never-syncs.md

@@ -1,7 +1,7 @@
 # Design miss 08 — Non-item document state only syncs at seed; `lib_symbols` is a landmine for the symbol-libraries milestone
 
 **Severity:** design gap (silent divergence for settings edits; structural blocker later)
-**Status:** open decision
+**Status:** IMPLEMENTED 2026-07-03 — see [18](18-miss08-opts-12-13.md) (lib_symbols channel + coarse layout save-sync; nets stay seed-frozen by design)
 
 ## Where
 

docs/features/ysync-review/12-opt-hot-path-full-model-work.md

@@ -1,7 +1,7 @@
 # Optimization 12 — O(full-model) work on every edit, apply, and remote batch
 
 **Severity:** performance (fine on demo boards; seconds-per-edit territory at 5–10k items)
-**Status:** open
+**Status:** TS items DONE 2026-07-03 (zod off the observer path, children index once — see [18](18-miss08-opts-12-13.md)); C++ item 1 delivered by [17](17-fixes-bugs-01-07.md) batch 3 except the scalar-scan/legacy-wire retirement (goes with the legacy-wire removal)
 
 ## The costs, per hot path
 

docs/features/ysync-review/13-opt-parked-dirty-full-sheet-replace.md

@@ -1,7 +1,7 @@
 # Optimization 13 — Parked-dirty sheet rebind re-applies the entire sheet instead of the delta
 
 **Severity:** performance + UX (heavy on big sheets; creates the adopt undo-bomb)
-**Status:** open
+**Status:** FIXED 2026-07-03 — option 2 (diff on rebind) — see [18](18-miss08-opts-12-13.md)
 
 ## Where
 

docs/features/ysync-review/14-opt-item-granularity-bandwidth.md

@@ -1,7 +1,7 @@
 # Optimization 14 — Item-level body granularity: whole-item payloads per nudge, LWW drops concurrent property edits
 
 **Severity:** known/documented v1 tradeoff — recorded here so its costs are visible when prioritizing
-**Status:** open (deliberate design decision; revisit trigger below)
+**Status:** open (deliberate design decision; revisit trigger below — reaffirmed 2026-07-03, see [18](18-miss08-opts-12-13.md))
 
 ## Where
 

docs/features/ysync-review/18-miss08-opts-12-13.md

@@ -0,0 +1,102 @@
+# Miss 08 + opts 12/13 implemented; opt 14 deliberately deferred (2026-07-03)
+
+**Status:** miss [08](08-miss-layout-state-never-syncs.md) (both halves), opt
+[12](12-opt-hot-path-full-model-work.md)'s TS items, and opt
+[13](13-opt-parked-dirty-full-sheet-replace.md) implemented and verified. All
+TS/shared-side — the C++ already did its part (eeschema's `itemBlob` emits the
+`lib_symbols` context; `doApplyItems`' `findLib` was designed to prefer a
+blob-carried definition), so no WASM rebuild was needed.
+
+## 08A — lib_symbols channel
+
+- New `kdoc_libsymbols` Y.Map (lib id → `(symbol …)` definition text): concurrent
+  placements of DIFFERENT symbols merge per definition instead of LWW-clobbering
+  one layout slot.
+- `docToY` extracts the layout's `(lib_symbols …)` definitions into the map and
+  keeps the layout slot EMPTY (the injection point); `yToDoc` re-injects the
+  map's definitions sorted by lib id — the order KiCad's own writer emits, so
+  materialization matches editor saves.
+- Emit direction: `wireLibSymbols(wire)` recovers definitions from the
+  multi-form clipboard blob (`unwrapWireItem` still strips them from the ITEM
+  payload); the binding stores them in the same transaction as the item delta.
+- Apply direction: `deltaToItemsWire(delta, view, libDefs)` prefixes a root
+  item carrying `(lib_id …)` with its definition — exactly the multi-form shape
+  eeschema's paste path parses, so `findLib`'s first branch resolves it and a
+  peer that has never seen the symbol renders it correctly.
+- e2e: `tests/kicad/ysync-libsymbols.spec.ts` — a joiner whose cold copy lacks
+  the symbol adopts it WITH its definition (chromium two-tab; F2 applies).
+
+## 08B — coarse layout save-sync
+
+- New shared `syncLayoutToY(fileDoc, ydoc, origin)`: reconciles non-item layout
+  slots per HEAD KEYWORD group (title block, paper, setup, settings…) from a
+  just-saved file — a changed group is replaced wholesale (LWW at head
+  granularity; different heads merge). `{item}` slots are never touched.
+- Deliberate freezes: `net` (pcbnew's root net table — net-creating edits are
+  not possible in the standalone; repeated positional heads can't be reconciled
+  by name) stays seed-frozen; `lib_symbols` routes to the defs map ADDITIVELY
+  (a save can't know about a peer's not-yet-applied placement).
+- Wiring: `registerSaveHook` gained `onSavedText` (decoded saved text);
+  WasmTool routes it — eeschema per sheet via the manager's new
+  `syncLayoutFromSave` (parked rooms sync too; the dirty mark it causes costs
+  only the real delta now, see opt 13), pcbnew/pl_editor via the single-room
+  doc.
+- Known limitation (unchanged from the doc's "coarse but converging"): a peer's
+  EDITOR does not live-update non-item state — the room doc converges, so
+  materialization/reopen and drift-detect see it; live propagation into an open
+  editor's title block would need a C++ apply for non-item state.
+
+## Opt 12 — TS hot-path (items 2 + 4)
+
+- `yToItemUnchecked` (no zod) feeds the binding's `itemsView()` — both hot
+  directions (every local emit, every remote batch). zod stays at the trust
+  boundaries: wire parse, seed, materialize.
+- `itemsWireToDelta` builds the parent→children index ONCE per conversion
+  (was: full-scan `descendants()` per wire item and per removed id).
+- NOT taken from doc 12: retiring the C++ scalar scan + legacy emit (the scan
+  still feeds the legacy wire and covers eeschema's unreported post-Push
+  connectivity cleanup — retire it together with the legacy-wire removal,
+  miss 11 follow-up), and the lazy `deltaToItemsWire` view (item 3) — killing
+  zod removed the dominant cost; revisit if profiling says otherwise.
+
+## Opt 13 — diff-on-rebind adopt (option 2)
+
+`seed()`'s adopt no longer renders and re-applies EVERY doc root. It diffs the
+editor snapshot against the doc view (`itemsWireToDelta` + `wireItemUuids`) and
+applies only the doc-authoritative difference:
+
+- doc-only ROOTS → added (their sexprs embed descendants; a doc-only child makes
+  its shared parent differ and rides the parent's re-apply);
+- differing items → the DOC's version re-applied, lifted to their root (the C++
+  upsert replaces roots; a bare child apply would mis-parent);
+- editor-only ROOTS → removed (editor-only children vanish with their parent's
+  re-apply).
+
+An empty diff degrades to baseline-only — the parked-dirty rebind, the clean
+revisit, and the cold divergent adopt now share one code path, and the adopt's
+single commit (and undo entry — the miss-09 "adopt undo bomb") shrinks to the
+real changed set.
+
+## Opt 14 — deferred, on purpose
+
+The slot-level CRDT refinement is a meaningful rewrite of `kicad-y`'s write path
+plus the whole conversion layer, with real interleaving-anomaly risk. Doc 14's
+own revisit triggers (measured bandwidth/storage cost; concurrent same-item UX
+complaints) are unmet, and the flatten already gives per-child granularity.
+Nothing in this batch forecloses it — `body` stayed one JSON value.
+
+## Verification
+
+- pcbjam-shared: 107 (9 new in `test/layout-libsymbols-sync.test.ts`)
+- standalone: 79 + 2 known pre-existing wasm-assets fixture failures
+  (collab suite 42, incl. 3 new diff-adopt + 2 lib_symbols binding tests;
+  save-flow +2)
+- e2e (chromium): full ysync set + `ysync-libsymbols.spec.ts` green
+- No C++ changes; no WASM rebuild.
+
+## Remaining from the review
+
+Misses [09](09-miss-undo-not-collab-aware.md) (collab-aware undo — the adopt
+shrink here removes its worst case) and [10](10-miss-no-repair-path.md) (drift
+repair), opt 12's C++ retirement half (with the legacy-wire removal), opt 14
+(triggers above), and doc 17's carried-over follow-ups.