## Summary
Brings every serialization-related doc, skill, and the CLAUDE.md rule in line with generator **v4** (adopted in #2586/#2587). No code changes.
**Updated surface, everywhere it was referenced:**
- `[SerializableFieldSaveFlag(order)]` / `[SerializableFieldDefault(order)]` → `[SaveFlag(nameof(Should), nameof(Default))]` on the field (second method optional).
- `[TimerDrift]` + `[DeserializeTimerField(order)]` → `[DeserializeTimer(nameof(Method), wallClock)]` on the field, with the anchored-time semantics spelled out: drifting by default (downtime preserves the remaining delay, idle saves byte-stable), `wallClock: true` for absolute deadlines, restart method invoked **only when a timer was running** (no sentinel), and the timer `MigrateFrom` pattern (`XxxNext`/`XxxDelay`) for wire-format changes.
- New `[SerializableField]` documentation: the real signature (the documented `saveIf` parameter never existed) plus the setter hooks — `allowFieldChange` (`bool Method(ref T value)`: coerce/veto before assignment) and `fieldChanged` (`void Method(T oldValue, T newValue)` after) — with the generated pipeline and the SG3015/SG3018 guardrails.
- `[SerializableProperty]` guidance narrowed to its remaining purpose: custom getters and setter semantics the hooks cannot express.
- `[AnchoredDateTime]` documented alongside `[DeltaDateTime]` (now marked legacy, with the version-bump warning for converting between them).
**Files:** `dev-docs/serialization.md`, `dev-docs/timers.md`, `dev-docs/claude-skills/modernuo-serialization.md`, `dev-docs/claude-skills/modernuo-timers.md`, `dev-docs/runuo-migration-docs/02-serialization.md`, `dev-docs/runuo-migration-docs/03-timers.md`, and a condensed v4 addition to CLAUDE.md rule 9.
**Example refresh:** the skill's `BagOfSending` "custom properties" example was itself converted in #2587 — it is now quoted in its real post-conversion form as the canonical hooks example; the real-examples list points at `BaseWeapon.cs` for custom getters and `BaseLight.cs` for the drifting-timer + `MigrateFrom` pattern.
Verified by grep: zero references to the removed v3 attribute names remain anywhere in `dev-docs/` or `CLAUDE.md`.
## Summary
Hardens the **Advanced Search** engine (`Projects/UOContent/Engines/Advanced Search/`) — the GM entity finder that fans searches across background worker threads. A code review surfaced 14 defects (A–N), including a shard-crasher reachable from a single admin typo and a path that silently disables autosave for the rest of the shard's uptime. Each behavioral fix ships with a test.
Full `UOContent.Tests` suite: **530/530 green** (21 new AdvancedSearch tests).
## Fixes
### Crash / data-loss
- **A — Shard crash on a malformed Property Test.** `AdvancedSearchThreadWorker.Execute` had no `try/catch` and the worker `Thread` is foreground, so a parse throw (`Hits>abc`, `Layer=onehanded` — `Enum.Parse` was case-sensitive, `Hits>1@` — empty sub-expression indexing) terminated the process. Now: `ParseValue`/`CompareValues` use `TryParse`/`Enum.TryParse(ignoreCase)` and return no-match instead of throwing; the per-entity filter is wrapped in `try/catch` (logs + skips); empty expressions are guarded.
- **C — Overlapping searches corrupt state + brick autosave.** `_threadWorkers`/`_threadId` were `static` but `DoSearch` is an instance method; a second search (double-click / two admins) stomped shared worker state and could leave a drain waiting forever on the shared `AutoResetEvent`, so `AutoSave.SavesEnabled` was never restored. Now: an `Interlocked` re-entrancy guard rejects concurrent searches.
- **G — Autosave restore not guaranteed.** The restore lived only in the success callback. Now it's in a `finally` (plus an outer `catch` covering the synchronous setup and a `catch` on the drain body), so autosave + the guard are always released.
### Wrong results
- **D — `@`/`|` operator precedence.** `a@b|c` evaluated as `a && (b || c)` instead of `(a && b) || c`. OR now binds looser than AND (`AdvancedSearchUtilities.EvaluateBoolean`, unit-tested).
- **E — Descending sort, partial last page rendered blank** (the index decreased in descending mode and the `break` early-out killed the loop). Now a bounded `VisibleCount`-driven loop renders the last page in both directions.
- **F — Deleted entities** were not skipped (ghost rows). Now `DoEntitySearch` skips `entity.Deleted`.
- **N — Reference-type comparisons** threw (`Comparer<T>.Default.Compare` on non-`IComparable`) and compared references to a string. Now equality is by value and ordering is guarded to `IComparable` (no throw).
### Worker perf / hardening
- **H** busy-spin → `Thread.Yield()` in the drain; **I** `GetProperties()` cached per `Type`; **J** `HandleValidInternal` moved behind the cheap map/range/region filters; **K** worker threads are `IsBackground` + `Exit()` tolerates an already-terminated worker; **L** `_filter == null` guard; **M** consistent `Volatile` access on `_pause`/`_exit`.
### Documented
- **B** — the residual worker/event-loop read race is documented on `AdvancedSearchThreadWorker`: workers read live entity state concurrently with the loop, so value-type reads may be stale-but-safe and getter exceptions are swallowed; fully eliminating it would require snapshotting entity fields on the main thread (deferred).
## Notes
- New test-only seams (`TryBeginSearch`/`EndSearch`/`IsSearchInProgress`/`VisibleCount`/`TryParseValue`/`EvaluateBoolean`) are `internal` via the existing `InternalsVisibleTo("UOContent.Tests")`.
- Dead `public ParseValue<T>` removed.
- `ConcurrentDictionary` for the reflection cache is intentional — these workers are genuinely parallel.
