refactor(srp): remove renderer fullscreen stage heuristics

docs/used/SRP_UniversalExplicitFullscreenStagePlanningPlan_完成归档_2026-04-21.md

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+# SRP Universal Explicit Fullscreen Stage Planning Plan 2026-04-21
+
+## Goal
+
+Remove renderer-level fullscreen stage request heuristics and make managed URP fullscreen stage ownership explicit through renderer features.
+
+## Why This Stage
+
+Current managed URP already owns more of the camera-frame plan, but one important seam is still implicit:
+
+1. `ScriptableRenderer.ConfigureCameraFramePlan(...)` scans queued render passes;
+2. it infers whether `PostProcess` or `FinalOutput` should exist from `RenderPassEvent`;
+3. fullscreen stage planning therefore still depends on hidden pass-event heuristics instead of explicit managed planning code.
+
+That is weak architecture for a Unity-style SRP/URP direction. A renderer feature that needs a fullscreen stage should explicitly request it.
+
+## Scope
+
+Included:
+
+1. remove fullscreen-stage inference from `ScriptableRenderer`;
+2. make first-party post-process-style feature planning explicit;
+3. keep builtin final-color feature on explicit planning path;
+4. rebuild `XCEditor` and run old editor smoke.
+
+Not included:
+
+1. moving all native fullscreen request legacy paths out of the engine;
+2. deleting native final-color or vector fullscreen pass implementations;
+3. deferred renderer work;
+4. editor UI work.
+
+## Acceptance
+
+This stage is complete when:
+
+1. `ScriptableRenderer` no longer auto-requests fullscreen stages from queued pass events;
+2. first-party managed fullscreen features explicitly request the stages they need;
+3. `XCEditor` build passes;
+4. old editor smoke passes and `editor.log` contains a fresh `SceneReady`.
+
+## Validation
+
+Validated on 2026-04-21:
+
+1. built old editor target with `cmake --build . --config Debug --target XCEditor` from `build/`;
+2. launched `editor/bin/Debug/XCEngine.exe` for about 12 seconds;
+3. verified fresh `editor/bin/Debug/editor.log` contains `SceneReady`.
+
+Observed log line:
+
+`[2026-04-21 13:06:17] [INFO] [General] [SceneLoadTrace] SceneReady elapsed_ms=5372 first_frame_ms=536 peak_pending_async=9`