[Lluvia-C]

Summary

• Validate the declared default resource profile before the central scheduler publishes its endpoint or starts workers.
• Fail closed when a GPU-only task has no structurally usable accelerator, while preserving transient resource-pressure queueing.
• Reject generations that never admitted an evaluation-capable job before writing generation results or committing the next boundary.
• Add offline regression contracts for scheduler preflight, cohort zero-evaluation handling, and custom topology generation handling.

Validation

• 132 targeted and related unit tests passed.
• Ruff check and format check passed for all changed files.
• Targeted Pyrefly check passed with 0 errors.
• git diff --check passed.
• No real GPU, API key, network task, or external task checkout is required by these tests.

The broader local unit run also passed 2915 tests; remaining failures were environment-dependent checks involving missing optional dependencies, macOS process-group behavior, and generated bytecode/cache integrity.