BindBlockReferences

BindBlockReferences validates the block graph and attaches lazy placement views. Every container must select known definitions without repeats; the definitions must be acyclic, keep every placement path within the nesting and query path bounds (see pathExtent), and derive distinct stable IDs (see validatePlacementIDs). Each check visits every definition once, so validation cost follows the number of definitions rather than placements. It does not evaluate access, defaults, hooks or other executable behavior. Failures are a *ValidationError naming the responsible definitions.