ModernUO/CLAUDE.md
Kamron Batman c9831b9680
fix: TextDefinition was uneditable in the props gump, and where parsed constants its own way (#2624)
## Pressing `>` on a TextDefinition did nothing useful

`#1217` moved `TextDefinition` into the Server project for serialization support and added `[PropertyObject]` along the way. `PropsGump` checks that attribute **before** its parsable fallback, so from that commit on the button either drilled into a read-only `Number`/`String` page (both get-only since `#1221`, so no `>` buttons — a dead end) or, when the value was null, re-sent the same page and looked inert.

Worth being clear that `#765` — which replaced the hand-maintained type list with a generic `IsParsable` branch — was **not** the regression. At that commit `TextDefinition` was `[Parsable]` only, fell through to the new branch, and the editor worked. Only the later attribute hijacked the routing.

`TextDefinition` is now caught ahead of the `[PropertyObject]` branch and routed to `SetGump`, which has had `TextDefinition`-specific code at line 35 all along.

## `0` and `"0"` could not be told apart

`Commands.Split` strips quotes before any parser runs, so this was never fixable in `TextDefinition.Parse` alone — the information is gone two layers earlier. The markers now travel inside the value:

| Input | Result |
|---|---|
| `1060847` | cliloc (unchanged) |
| `#1060847` | cliloc, explicit — the form `ToString()` already writes |
| `@"1060847"` | the literal string |
| `hello` | string (unchanged) |
| `(-null-)` | null (unchanged) |

`GetValue()` quotes a string that would not survive the trip back. That check is a real round trip through the parser rather than a pattern match, so it cannot drift from it. `Types.TryParse` decodes the same escape for plain strings — which is what `[get` has always written for the literal `"null"` without `[set` ever reading it back.

**Saved data is untouched.** Serialization reads a discriminated flag plus int/string (`IGenericReader.cs:175`) and the JSON converter switches on token type; neither calls `Parse`, so a stored string `"1060847"` stays a string and spawner JSON is unchanged. The new syntax stays in the text and command layer, where it reaches `[set`, `[add`, spawner props, the props gump and Advanced Search.

## `where` still parsed its constants its own way

`#2625` carried the hand-rolled constant parser across to `PropertyExpressions.Parse` unchanged. It looks for a static `Parse` overload on the property type and gives up if there is none — and `Type` and `IEntity` have neither:

```
where Subject Kind  = Static     ->  Unable to convert string "Static" into type 'System.Type'.
where Subject Owner = 0x1        ->  Unable to convert string "0x1" into type 'Server.Mobile'.
```

Both resolve fine for every other command. Routing through `Types.TryParse` picks up type-name lookup, entity resolution by serial, and the `@"..."` literal convention, so a value that works in one place now works everywhere. It also deletes the duplicate parser (−56 lines in `PropertyExpressions`).

Two things are load-bearing and preserved. `where` has always spelled a null constant as a bare `null`, where `[set` uses `(-null-)`; the shared parser reads a bare `null` as the text, so the null case is handled ahead of it and `= null` keeps meaning null. And nullable targets still unwrap first, so `where <int? prop> = 5` is unaffected.

Bare and hex integers, enums, bools, strings, `Map`, and TextDefinition's `#` / `@"..."` markers all resolve exactly as before — 13 of the 15 tests in `WhereConstantParsingTests` pin that and passed before the change as well as after.

## Documentation

The generic command system had no documentation anywhere in the repo: scopes, `where` and its operators, dot notation, `order by` / `distinct` / `limit`, the value and quoting syntax, `[interface` and `[batch` were all learn-by-reading-the-source. `dev-docs/generic-commands.md` covers them, linked from `CLAUDE.md` and `commands-targeting.md`, and points at <https://muo.gg/commands> for the per-command list rather than duplicating it.

Two behaviours it records that were news to me while writing it:

- `Contained` honours conditions on the normal command path but never sets `SupportsConditionals`, and `[batch` is the only place that reads the flag — so the same condition works typed directly and is refused under batch.
- `Multi`, `Single`, `Self` and `Serial` do not parse modifiers at all, so a `where` clause there is passed to the command as ordinary arguments rather than rejected.

Comments in the changed code were trimmed to what is not evident from the code itself; the rationale they carried is either in the doc now or in the commit that introduced it.

## Behavior changes worth a reviewer's attention

Two things go beyond strict bug-fixing, both deliberate:

- **Hex now parses into a TextDefinition.** Consolidating the three `Parse` overloads onto one span codec means `[set Message 0x102CE7` is cliloc 1060847 rather than the string. Previously only the 1-arg `Parse(string)` did hex and nothing called it. This makes the props gump's own `1060847 (0x102CE7)` display typeable.
- **`@"..."` decodes generally for strings**, not only the exact token `@"null"`. So `[set Name @"hello"` sets `hello`. A half-working escape seemed more surprising than a general one, and the `where` path already decoded it — but narrowing it back is a one-line change if preferred.

## Testing

40 tests, each written first and watched fail for the right reason. They cover the props gump routing (populated and null), cliloc/string/quoted parsing and `GetValue` round trips, `where` constant resolution for Type- and entity-valued properties, and the bare-`null` vs `@"null"` distinction that must not drift.

One sort case is added that #2625 left uncovered: ordering a value-typed chain whose intermediate is null, which reads as `default(int)` rather than throwing. Two other tests from the pre-rebase branch were dropped as duplicates of `ConditionalCompilerEdgeTests`.

Rebased onto `535a09899`. `dotnet build` clean, 0 warnings. **902 UOContent** and **869 Server** tests pass, 0 failures.

## Known gaps

- `Nullable<T>` comparisons work via #2625's lifted operators; nothing here changes that.
- Spawner **Params** are split on plain spaces (`BaseSpawner.cs:1035`) rather than through `Commands.Split`, so a constructor argument still cannot contain one. Untouched here — a tokenizer issue, not a TextDefinition one.
- `Types.ParseStringNumericParamTypes` is now unreferenced. Left in place because it is public and shards may use it.
2026-09-10 19:36:30 -07:00

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# ModernUO
.NET 10 Ultima Online server emulator. Single-threaded game loop. All game logic runs on one thread.
- **Server engine**: `Projects/Server/` — do NOT modify without explicit request
- **Game content**: `Projects/UOContent/` — primary editing target
- **Build**: `dotnet build` from repo root
## Code Audit Rules
Apply these when writing or reviewing `.cs` files under `Projects/`.
1. **LINQ** — Tier 1 (zero-cost patterns) free on hot paths; Tier 2 (low overhead) OK on warm paths; Tier 3 (allocating) forbidden on hot paths → `dev-docs/code-standards.md`
2. **No `Console.WriteLine`** — use `LogFactory.GetLogger(typeof(MyClass))``logger.Information(...)` (requires `using Server.Logging;`)
3. **Threading policy** — game logic runs only on the main loop; **never** touch game state (`World`, mobiles, items, maps, timers) from a background thread. Heavy work that *needs* game state must be **chunked** across ticks, not threaded. Heavy work that does *not* need game state (large-file parse, external I/O) **must** run on a background thread **and must yield to world saves** (defer while `World.Saving`/`WorldState.PendingSave`). Publish results back to the loop as an immutable snapshot swapped via a single `volatile` reference — the only sanctioned `volatile`. No `lock`/`Mutex`/`ConcurrentDictionary` in game logic. Rule #10 covers how background work hands results back to the loop → `dev-docs/threading-model.md`
4. **No `World.Mobiles`/`World.Items` iteration** — use spatial queries: `map.GetMobilesInRange<T>()`, `map.GetItemsInRange<T>()`
5. **Clean up refs in `OnDelete()`/`OnAfterDelete()`** — null out `Item`/`Mobile` references
6. **Cancel timers in `OnDelete()`/`OnAfterDelete()`** — call `_token.Cancel()` or `_timer?.Stop()`
7. **`STArrayPool<T>.Shared`** not `ArrayPool<T>.Shared` — single-threaded optimized, no locks
8. **`PooledRefList<T>`** not `new List<T>()` on hot paths — zero GC pressure, stack-allocated ref struct
9. **Serialization** — class must be `partial`, constructor needs `[Constructible]`, `TimerExecutionToken` must NOT have `[SerializableField]`. New classes: use `[SerializationGenerator(version)]` (omit `encoded`). Setters that coerce/veto/run side effects: use `[SerializableField]` args `allowFieldChange: nameof(BoolRefMethod)` / `fieldChanged: nameof(OldNewMethod)` — reserve `[SerializableProperty]` for custom getters. Serializable `Timer` members declare `[DeserializeTimer(nameof(Method))]` on the field (anchored by default — downtime preserves remaining delay; `wallClock: true` = absolute; method runs only when a timer was running at save). Conditional writes: `[SaveFlag(nameof(Should), nameof(Default))]` on the field. When bumping versions, add `MigrateFrom(VXContent)` (X = previous version). Never modify `Deserialize(reader, version)` for version bumps — that method is only for pre-codegen legacy saves. When migrating from pre-codegen Serialize/Deserialize: pass `false` if old code used `reader.ReadInt()`, bump version +1, and keep old logic as `private void Deserialize(IGenericReader reader, int version)``dev-docs/serialization.md`, `dev-docs/runuo-migration-docs/02-serialization.md`
10. **No `Task.Run`/`new Thread()` for game logic** (tandem with rule #3) — game logic is the single-threaded event loop. Backgrounding is allowed only for work that does not itself touch game state (external service calls, large-file parse). **Prove the need before adding a thread**: measure **on-loop** time, not wall-clock (frozen world is the cost, player latency is not), and gate on `Environment.ProcessorCount` — off-loading creates no CPU and buys nothing on 12 cores. New workers go in the vetted table in `dev-docs/threading-model.md` with their measurement. When such work must *feed* game logic: run the heavy/I/O part off-loop and `ConfigureAwait(false)` its awaits so a continuation never resumes on the loop and silently foregrounds heavy work; then hand the result back **explicitly** — publish an immutable snapshot swapped via a `volatile` reference (the loop reads it lock-free), or marshal the apply step with `Core.LoopContext.Post(() => …)`, re-validating in the continuation whatever may have changed while it ran. Never touch game state off-thread; never let the scheduler decide where the heavy work runs → `dev-docs/threading-model.md`
11. **Never assume era** — if code uses `Core.AOS`/`Core.SE`/etc., ask which expansion to target
12. **Naming**`_camelCase` private fields, `PascalCase` properties/methods/classes; don't flag legacy `m_` but use `_` for new code
13. **No empty gumps** — every gump must produce visual elements. An empty gump leaks on client+server (no way to close it). Use static `DisplayTo()` to validate before constructing → `dev-docs/gump-system.md`
14. **PropertyList string literals must be holes**`$"{"Map"}\t{value}"` not `$"Map\t{value}"`. The handler treats bare text as delimiters, `{}` holes as arguments. Only `\t` should be a bare literal → `dev-docs/property-lists.md`
15. **Braces required on all control flow**`if`, `else`, `for`, `foreach`, `while`, `do`, `switch` must always have braces, even for single-line bodies → `dev-docs/code-standards.md`
16. **Prefer switch expressions and switch-when** — use switch expressions for value mapping and switch-when for pattern matching where they improve readability. Exception: skip if unreadable or cold path → `dev-docs/code-standards.md`
17. **No `System.Text.StringBuilder`** — use `ValueStringBuilder` with `stackalloc` (bounded output) or `ValueStringBuilder.Create()` (unbounded). Supports `$"..."` interpolation directly. Always use `using var` for disposal. Use `Reset()` instead of reassigning → `dev-docs/string-handling.md`
18. **Interpolation anti-patterns on handler-aware APIs**`Send*`/`Say`/`Emote`/`PublicOverhead*`/`IPropertyList.Add`/gump `AddLabel`/`AddHtml`/`Html.Center`/`SpanWriter.Write*` all have `ref RawInterpolatedStringHandler` overloads that allocate zero strings, but only when the call-site argument is a `$"..."` literal directly. Avoid: ternaries with interpolated branches (`Send(c ? $"a" : $"b")`), switch expressions with interpolated arms, pre-built `var s = $"..."` locals (single-use), `.ToString()` / `.String()` / `string.Format` inside holes, string concat (`{a + b}`), LINQ string ops in holes. Use `:L` format spec for lowercase (`{rank:L}` not `rank.ToString().ToLowerInvariant()`) → `dev-docs/string-handling.md` § Interpolation Anti-Patterns
19. **No `InvalidateProperties()` from inside `GetProperties`** — every property a `GetProperties` override reads must be a pure read. `InvalidateProperties()` rebuilds the list in place (`Reset()` + rebuild), and `Reset()` returns the pooled interpolation buffer — which the compiler rents for the whole `$"..."` expression, so every hole is evaluated while it is live — and rewinds the packet cursor. A getter that invalidates therefore throws `ArgumentNullException` (parameter `"array"`) out of `GetProperties` from an unrelated-looking line, or silently corrupts the tooltip. The engine refuses and logs an error; `DEBUG` throws. Lazy recomputation in a getter is fine — the *notification* is not. Invalidate in the setter that changes the value, or defer with `Timer.DelayCall(InvalidateProperties)``dev-docs/property-lists.md` § Never Invalidate From Inside `GetProperties`
20. **Tick-count math must be wraparound-safe** — compare `Core.TickCount`/`GetTimestamp()` values only by subtraction (`a - b < 0`, never `a < b`), no zero/sign sentinels on tick fields, seed deadline fields from a real tick (never rely on the 0 default). Cloud hypervisors (GCP) pass through the host's never-resetting counter: ticks start enormous and can wrap negative. Linux affected in production; Windows not so far → `dev-docs/tick-counts.md`
## Dev-Docs Reference
| Topic | File |
|---|---|
| Code standards & LINQ tiers | `dev-docs/code-standards.md` |
| Serialization system | `dev-docs/serialization.md` |
| Content patterns (Items, Mobiles, Creatures) | `dev-docs/content-patterns.md` |
| Era & expansion handling | `dev-docs/era-expansion.md` |
| Timer system | `dev-docs/timers.md` |
| Event scheduler (wall-clock/calendar) | `dev-docs/event-scheduler.md` |
| Object property lists (tooltips) | `dev-docs/property-lists.md` |
| Gump (UI dialog) system | `dev-docs/gump-system.md` |
| Commands & targeting | `dev-docs/commands-targeting.md` |
| Generic commands (`where`/`order by`/`distinct`, dot notation, `@""` literals, `[batch`, `[interface`) | `dev-docs/generic-commands.md` |
| Event system | `dev-docs/events.md` |
| Threading model | `dev-docs/threading-model.md` |
| Server hardware requirements | `dev-docs/server-requirements.md` |
| Debugging event-loop performance (profiling build, decomposition, GC/RAM) | `dev-docs/debugging-event-loop.md` |
| Tick-count overflow rules (subtraction comparisons; GCP pass-through counters) | `dev-docs/tick-counts.md` |
| Server lifecycle & bootstrap phases (Configure/ConfigurePrompts/Initialize) | `dev-docs/server-lifecycle.md` |
| Platform prerequisites (ICU, tzdata, native libs per distro) | `dev-docs/platform-prerequisites.md` |
| Configuration system | `dev-docs/configuration.md` |
| Networking & packets | `dev-docs/networking-packets.md` |
| IP bans, blocklists & allowlists (incl. unblocking a player) | `dev-docs/ip-bans-and-allowlists.md` |
| Region system | `dev-docs/regions.md` |
| String handling & ValueStringBuilder | `dev-docs/string-handling.md` |
| RunUO migration (overview) | `dev-docs/runuo-migration-docs/00-overview.md` |
| RunUO migration (all docs) | `dev-docs/runuo-migration-docs/` |
## Claude Skills (Opt-In)
Detailed Claude Code skills live in `dev-docs/claude-skills/`. They are **not auto-loaded** — they must be copied to `.claude/skills/` to activate.
**When to offer**: If the user is building complex content (new items, creatures, spells, gumps, quests, packets, serialization work, etc.), ask:
> I have detailed Claude Code skills for this kind of work. Want me to enable them?
> I'll copy the relevant files from `dev-docs/claude-skills/` to `.claude/skills/`.
Then copy only the relevant skill files based on the task:
| Task | Skills to enable |
|---|---|
| New Item or Mobile | `modernuo-content-patterns`, `modernuo-serialization`, `modernuo-property-lists` |
| Creature / spawn | `modernuo-content-patterns`, `modernuo-serialization`, `modernuo-timers` |
| Spell or ability | `modernuo-content-patterns`, `modernuo-serialization`, `modernuo-timers`, `modernuo-era-expansion` |
| Gump / UI dialog | `modernuo-gump-system`, `modernuo-commands-targeting` |
| Quest or event system | `modernuo-events`, `modernuo-content-patterns`, `modernuo-configuration` |
| Scheduled / seasonal / holiday events | `modernuo-event-scheduler`, `modernuo-timers` |
| Custom regions / dynamic areas | `modernuo-regions`, `modernuo-content-patterns` |
| Packet / networking | `modernuo-networking`, `modernuo-threading` |
| Commands | `modernuo-commands-targeting` |
| Timer work | `modernuo-timers`, `modernuo-serialization` |
| Config system | `modernuo-configuration` |
| Era-conditional code | `modernuo-era-expansion` |
| String building / formatting | `modernuo-string-handling` |
| Code review / audit | `modernuo-code-audit` |
| Any `.cs` file edit | `modernuo-code-audit` (always offer for code changes) |
| **RunUO Migration** | |
| Migrate any RunUO script | `migrate-from-runuo/migrate-foundation` (always), plus system-specific skills below |
| Migrate Item/Mobile/Creature | `migrate-from-runuo/migrate-foundation`, `migrate-from-runuo/migrate-serialization`, `migrate-from-runuo/migrate-items-mobiles` |
| Migrate serialization | `migrate-from-runuo/migrate-serialization` |
| Migrate timers | `migrate-from-runuo/migrate-timers` |
| Migrate gumps | `migrate-from-runuo/migrate-gumps` |
| Migrate packets | `migrate-from-runuo/migrate-packets` |
| Migrate property lists | `migrate-from-runuo/migrate-property-lists` |
| Migrate events/commands | `migrate-from-runuo/migrate-commands-events` |
| Migrate persistence (WorldSave) | `migrate-from-runuo/migrate-persistence` |
| Migrate multi-file system | `migrate-from-runuo/migrate-systems` |
To enable a skill — Claude Code loads `.claude/skills/<name>/SKILL.md`; a bare `.md` dropped
directly into `.claude/skills/` is **not** picked up, and newly installed skills appear in the
*next* session:
```sh
# Standard skills (modernuo-*)
mkdir -p .claude/skills/<name> && cp dev-docs/claude-skills/<name>.md .claude/skills/<name>/SKILL.md
# Migration skills — sources live in the migrate-from-runuo/ subfolder, but install under the
# bare skill name (the table's "migrate-from-runuo/<name>" is the source path, not the name):
mkdir -p .claude/skills/<name> && cp dev-docs/claude-skills/migrate-from-runuo/<name>.md .claude/skills/<name>/SKILL.md
```
Migration skills reference the deep docs in `dev-docs/runuo-migration-docs/` and point to existing ModernUO skills for best practices.
The `modernuo-code-audit` skill auto-triggers on `.cs` file edits and flags convention violations (warnings only, asks before fixing).