Tooling: ComponentSerializerCoverageTest forward check only scans Components.h -> forgotten non-trivial subsystem-header component escapes the data-loss guard #545

Summary

ComponentSerializerCoverageTest.EveryDeclaredComponentIsHandledBySceneSerializer — the guard that is supposed to catch "you added a component and forgot to serialize it" (the #325-class silent-data-loss species) — builds its declared universe from the raw text of Components.h only. Components declared in subsystem headers (not Components.h) are outside its universe, so a forgotten non-trivial subsystem-header component escapes the check entirely.

Evidence

• ComponentSerializerCoverageTest.cpp:83: headerSrc = ReadFile(componentsHeader) (a raw text read — #includes are not expanded); line :96 iterates the struct \w+Component regex over headerSrc only.
• Many serialized components live outside Components.h: e.g. struct InventoryComponent in Gameplay/Inventory/InventoryComponents.h (hand-written serialize SceneSerializer.cpp:5282, deserialize :3090); likewise AbilityComponent, IKTargetComponent, QuestJournalComponent, NavMeshBoundsComponent, StreamingVolumeComponent, the AI components, etc.
• The asymmetry: the sibling ComponentTupleCoverageTest (ComponentHeaderRoots(), ~16 headers) and the inverse half of this same test (componentHeaderRoots, ~line 187) both scan the full subsystem-header list. Only the forward check regressed to Components.h-only. (CLAUDE.md's "greps a fixed header list" describes the inverse check — the forward missing-serialization guard does not cover subsystem headers.)

Reproduction

Add a non-trivial component (e.g. struct FooComponent with a Ref<T> field) to any subsystem header (say AIComponents.h) and forget its hand-written SceneSerializer.cpp block. It is classified non-trivial (so not auto-generated), never hand-written, and not in declared (not in Components.h) → the forward test passes → silent scene-YAML data loss ships, undetected by the very guard meant to prevent it.

Fix direction

Repoint the forward check's declared set at the full header-root list the inverse check + ComponentTupleCoverageTest already use (ComponentHeaderRoots() / componentHeaderRoots), so the forward and inverse checks share one component universe. Trivial change; it closes a real hole in a data-loss safety net.

Score

capability: 1
craft: 1
stability: 5
decay: 3
effort: 1
confidence: 1.0
learning: 1
fun: 2
kano: table-stakes
blocked_by: []
blocks: []

_{Rated per issue-scoring · score = confidence × (capability + craft + stability + decay) / effort, derived by the picker.}