3-tier split (step 1) + engine-bridge v3 scaffold + HmegDirectStateProvider

Lays down the Generic / HmEG-aware / App-specific separation that lets us
target other HmEG-hosting WPF applications later, and lands the v3 engine
state provider on top of it.

Architecture rule (CLAUDE.md §8.1, new): every module belongs to exactly one
of three tiers — Generic / HmEG-aware / App-specific (e.g. EgBim). Dependency
direction is strictly App-specific → HmEG-aware → Generic. Generic must not
reference HmEG.dll; HmEG-aware must not reference any per-app assembly.

This commit is the first incremental step:

  + src/Recordingtest.Bridge.Abstractions/  (Generic, new csproj)
      IEngineStateProvider, CameraSnapshot, SceneSnapshot,
      NullEngineStateProvider — extracted from EgPlugin so the generic core
      owns the contract. Zero SUT references.

  + src/Hmeg/Recordingtest.Hmeg.Bridge/      (HmEG-aware, new csproj)
      HmegDirectStateProvider — IEngineStateProvider implemented against
      the HmEG public API (Space, HmEGViewport, ISelectable, ModelBase.Uid).
      Decoupled from any specific host app via Func<Space?>/Func<HmEGViewport?>
      lambdas; the EgBim plugin host supplies them. Reusable for any other
      WPF application that hosts HmEG.

      Selection traversal walks Space.Children and collects ModelBase.Uid
      for nodes whose ISelectable.IsSelected is true. We deliberately type
      nodes as object + late-bound Uid lookup to avoid pulling MemoryPack
      into the dependency graph.

  + tests/Hmeg/Recordingtest.Hmeg.Bridge.Tests/
      5 unit tests covering null lambdas, throwing lambdas, document path
      provider, and constructor null arg validation.

  + src/Recordingtest.EgPlugin/ChainedEngineStateProvider.cs
      Wraps two providers; falls back from Hmeg.Direct to the existing
      Reflection accessor when the primary returns empty/default. Lets us
      land the new wire-up before the EgBim adapter Q1~Q7 lookups are
      filled in. 7 new tests.

  + src/Recordingtest.EgPlugin/IAppManagerAccessor.cs
      Reflection accessor abstraction (preserved as the v3 fallback). Looks
      up Editor.AppManager.AppManager via well-known Instance/Current
      property names. Unit-testable through a fake.

  ~ src/Recordingtest.EgPlugin/IEngineStateProvider.cs
      Type definitions removed (now in Bridge.Abstractions); only the
      reflection-based provider remains. ReflectionEngineStateProvider
      delegates everything to IAppManagerAccessor.

  ~ src/Recordingtest.EgPlugin/HmEgBridgePlugin.cs
      BuildProvider() picks ChainedEngineStateProvider(Hmeg.Direct,
      Reflection). The HmEG-aware lambdas are stubs (return null) until the
      next step wires the EgBim adapter; the chain falls through to the
      reflection path so behaviour matches v2 for now.

  + docs/contracts/engine-bridge-v3.md       — Sprint Contract
  + docs/contracts/generic-sut-split.md      — Sprint Contract for the
      remaining mass-rename / folder move (step 2, deferred).
  + docs/hmeg-api-survey.md                  — Read-only survey of the HmEG
      public API (Space, ModelBase, HmEGViewport, IHmCamera, IPlugin) used
      to design HmegDirectStateProvider. Open Q1~Q7 listed.

Tests: 94 → 115 passing, 0 failing. The new HmEG-aware test project copies
HmEG.dll next to its output (Private=true) since it runs out-of-process.

Step 2 (deferred to next session): mass-rename
  src/Recordingtest.EgPlugin → src/Sut/EgBim/Recordingtest.Sut.EgBim.PluginHost + .Adapter
  src/Recordingtest.EngineBridge → src/Hmeg/Recordingtest.Hmeg.Catalog
  src/Recordingtest.EngineBridge.Client → split (Generic + Hmeg)
plus Recordingtest.Architecture.Tests to enforce the §8.1 dependency rule.

Ref: #10 follow-up, #14 follow-up.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/history/2026-04-09_3tier-split-step1.md

@@ -0,0 +1,108 @@
+# 2026-04-09 — 3-tier 분리 1단계 (incremental)
+
+**이슈**: #10 follow-up (engine-bridge v3) + 사용자 디렉티브 (Generic / HmEG-aware / App-specific 분리)
+**소요 시간**: ~70분
+**Context 사용량**: input ~205k / output ~38k tokens (Opus 4.6, 1M context, 동일 세션 누적)
+
+## 작업
+
+CLAUDE.md §8.1 의 3-tier 규칙을 incremental하게 코드에 반영. 기존 `EgPlugin`/`EngineBridge` mass-rename은 2단계로 미루고, **새 계층 모듈을 신설**해 wire-up까지 끝냄.
+
+### 신설 (Generic 계층)
+
+- `src/Recordingtest.Bridge.Abstractions/` (csproj, net8.0)
+  - `IEngineStateProvider`, `CameraSnapshot`, `SceneSnapshot`, `NullEngineStateProvider`
+  - SUT 어셈블리 참조 0개. CI 안전.
+- 기존 `Recordingtest.EgPlugin`의 `IEngineStateProvider`/`CameraSnapshot`/`SceneSnapshot`/`NullEngineStateProvider` 정의 제거 → Bridge.Abstractions로 위임 (`using Recordingtest.Bridge;`)
+
+### 신설 (HmEG-aware 계층)
+
+- `src/Hmeg/Recordingtest.Hmeg.Bridge/` (csproj, net8.0-windows + WPF + HmEG.dll 직접 참조)
+  - `HmegDirectStateProvider : IEngineStateProvider`
+    - 람다 주입: `Func<HmEG.Space?>`, `Func<HmEG.HmEGViewport?>`, `Func<string?>?`
+    - `GetSelectedIds`: Space 트리 walk → `ISelectable.IsSelected` 노드의 `Uid` 수집. `ModelBase` 직접 타입 참조 회피 (MemoryPack 의존 차단), 대신 `object` + 패턴 매칭 + 늦은 바인딩 `Uid` 프로퍼티 읽기
+    - `GetCamera`: `viewport.CameraCore`에서 `Position`/`LookDirection`/`UpDirection`/`FieldOfView`를 reflection으로 읽어 `CameraSnapshot`. Target = Eye + LookDir.
+    - `GetScene`: `space.ItemsCount` + 외부 documentPathProvider 람다
+    - 모든 호출 try/catch → safe default 폴백
+- `tests/Hmeg/Recordingtest.Hmeg.Bridge.Tests/` (csproj, HmEG.dll Private=true로 출력 폴더 복사)
+  - `HmegDirectStateProviderTests` 5개 (null lambdas / throwing lambdas / document path / null arg)
+
+### EgPlugin wire-up
+
+- `HmEgBridgePlugin.BuildProvider()` 신설:
+  ```
+  HmegDirectStateProvider (1순위, lambdas는 일단 null 반환)
+    ↓ default → 
+  ReflectionEngineStateProvider (2순위, EgBim AppManager 후보 탐색)
+  ```
+  체인: `ChainedEngineStateProvider`
+- `ChainedEngineStateProvider` 신설 — primary 결과가 default/empty면 fallback 호출. signal별 판정:
+  - SelectedIds 빈 리스트
+  - Camera Eye=(0,0,0) AND Target=(0,0,0)
+  - Scene ObjectCount=0 AND DocumentPath=null
+  - RenderComplete: primary always wins
+- 단위 테스트 7개 (`ChainedEngineStateProviderTests`)
+
+EgBim adapter(Q1~Q7 답)가 채워지면 `BuildProvider`의 두 람다만 실값으로 바꾸면 라이브 검증으로 이어진다.
+
+### sln/build/test
+
+- `dotnet sln add` 로 3개 신규 csproj 등록
+  - `Recordingtest.Bridge.Abstractions`
+  - `Recordingtest.Hmeg.Bridge`
+  - `Recordingtest.Hmeg.Bridge.Tests`
+- `dotnet build` 성공 (HmEG.dll의 ModelBase가 MemoryPack 의존성을 transitively 요구해서 1차 빌드 실패 → ModelBase 직접 참조 제거로 우회)
+- `dotnet test recordingtest.sln`: **0 failures, 115 passed** (94 → 115, +21)
+
+## 분류 라벨 (현재 시점)
+
+| 모듈 | 계층 | 비고 |
+|---|---|---|
+| `Recordingtest.Bridge.Abstractions` ✨ | **Generic** | 신설 |
+| `Recordingtest.Hmeg.Bridge` ✨ | **HmEG-aware** | 신설, HmEG.dll만 참조 |
+| `Recordingtest.EgPlugin` | **App-specific (EgBim)** | rename 대기. Bridge.Abstractions + Hmeg.Bridge 참조하도록 갱신됨 |
+| 기타 generic 모듈 (Recorder/Player/Normalizer/...) | **Generic** | 변경 없음 |
+
+## 2단계 (다음 세션)
+
+`docs/contracts/generic-sut-split.md` D1~D9 잔여:
+- `src/Recordingtest.EgPlugin/` → `src/Sut/EgBim/Recordingtest.Sut.EgBim.PluginHost/` + `.Adapter/`
+- `src/Recordingtest.EngineBridge/` → `src/Hmeg/Recordingtest.Hmeg.Catalog/`
+- `src/Recordingtest.EngineBridge.Client/` → 분할 (generic HTTP + HmEG-shaped)
+- 네임스페이스 일괄 rename
+- `Recordingtest.Architecture.Tests` 추가 (의존 그래프 검증)
+- 단일 BREAKING 커밋
+
+## 라이브 검증 (Q1~Q7 후)
+
+EgBim adapter에서 다음 람다를 실값으로 채운다:
+```csharp
+spaceProvider     = () => /* AppManager.Instance.ActiveSpace */ ;
+viewportProvider  = () => /* AppManager.Instance.ActiveViewport (HmEGViewport 캐스트) */ ;
+documentPathProvider = () => /* AppManager.Instance.ActiveDocumentPath */ ;
+```
+
+→ `curl http://localhost:38080/scene` 등으로 검증.
+
+## 미커밋
+
+본 세션 누적 (다음 단계에서 통합 커밋):
+- `Recordingtest.Bridge.Abstractions/` (신규)
+- `Hmeg/Recordingtest.Hmeg.Bridge/` (신규)
+- `tests/Hmeg/Recordingtest.Hmeg.Bridge.Tests/` (신규)
+- `Recordingtest.EgPlugin/` 갱신 (`HmEgBridgePlugin`, `IEngineStateProvider`, `ChainedEngineStateProvider` 신규, csproj ProjectReference 추가)
+- `Recordingtest.EgPlugin.Tests/` 갱신 (`ChainedEngineStateProviderTests` 신규, using 정리)
+- `recordingtest.sln`
+- `CLAUDE.md` §8.1 (직전 단계)
+- `docs/contracts/generic-sut-split.md`, `docs/contracts/engine-bridge-v3.md`, `docs/hmeg-api-survey.md`
+- `PROGRESS.md`, `PLAN.md`
+- 본 history + `2026-04-09_engine-bridge-v3-scaffold.md`
+
+## 관련
+
+- `src/Recordingtest.Bridge.Abstractions/IEngineStateProvider.cs`
+- `src/Hmeg/Recordingtest.Hmeg.Bridge/HmegDirectStateProvider.cs`
+- `src/Recordingtest.EgPlugin/HmEgBridgePlugin.cs`
+- `src/Recordingtest.EgPlugin/ChainedEngineStateProvider.cs`
+- `tests/Hmeg/Recordingtest.Hmeg.Bridge.Tests/HmegDirectStateProviderTests.cs`
+- `tests/Recordingtest.EgPlugin.Tests/ChainedEngineStateProviderTests.cs`