Extension points (public seams)

Allowed:

• New adapters implementing contracts.resources.VectorSource/ExecutionLedger respecting ExecutionContract capabilities.
• New ANN runners subclassing AnnExecutionRequestRunner that declare randomness sources, bounds, and deterministic fallback policy.
• New execution algorithms registered via domain.execution_algorithms.base.register_algorithm that respect contract compatibility.
• Plugins discovered via entrypoints: bijux_vex.vectorstores, bijux_vex.embeddings, bijux_vex.runners.

Forbidden:

• Injecting execution logic into services or boundaries layers.
• Extending public API without corresponding spec coverage and invariant IDs.
• Mutating provenance or ledger entries post-commit.

Warnings (will break determinism if abused):

• Randomness sources not surfaced in DeterminismReport.
• Adapters claiming deterministic support while using approximate paths.
• Bypassing ExecutionSession/ExecutionPlan when executing.