core/comprehension_attempt/proposal.py: emit_proposal writes a content-addressed teaching/proposals/comprehension_failures/<hash>.json ONLY for growth-surface families (proposal_allowed). Deliberately toothless: status always proposal_only, mounted always false, requires_review always true (enforced in __post_init__); the problem text is hashed (sha256), never stored; filename = sha256(family:text_sha) so the same failure is idempotent.
No proposal for a correct wrong=0 boundary. Serving never reads the sink (scanned: generate/stream, field/propagate, vault/store, generate/derivation, core/reliability_gate). Routes through the existing proposal-only flywheel (ADR-0055/0056/0057), never a parallel correction path. README pins the contract. 6 tests.
