This branch studies projection-based recoverability in CFD with explicit separation between periodic and bounded domains. The distinction matters because boundary structure changes the protected class.
The periodic/Helmholtz lane gives exact projector behavior under compatible assumptions. The bounded-domain/Hodge lane includes both positive supported-family results and sharp failure boundaries when periodic logic is transplanted naively.
Canonical references are docs/cfd/incompressible-projection.md, helmholtz-hodge-velocity-projection.md, bounded-vs-periodic-projection.md, and docs/theorem-candidates/cfd-projection-results.md.
This branch is a primary example of geometry-sensitive recoverability: same information amount can still produce opposite outcomes when domain structure changes.