DADBEAR mirror FAQ redistill writes

[adamlevineagent]

Summary

• route FAQ redistill answer rewrites through get_faq_node + save_faq_node instead of a raw pyramid_faq_nodes update
• preserve existing 1/0 row semantics, including slug mismatch/no-match behavior
• add a C2 witness proving the rewritten FAQ answer survives .understanding/node-metadata rebuild

Context

DADBEAR EXECUTE faq-rewrite lane after #246 and #247, per PP dispatch msg/partner-prime/2026-06-22/dm-631e3a / msg/partner-prime/2026-06-22/dm-3e3053.

Evidence

• git diff --check
• cargo test -q faq_redistill_answer_survives_node_metadata_rebuild -- --nocapture
• cargo test -q faq_redistill_updates_only_target_and_never_deletes_or_batches -- --nocapture
• cargo test -q faq_redistill_no_match_updates_zero_rows -- --nocapture
• cargo test -q edge_survives_endpoint_supersession -- --nocapture
• cargo test -q faq_link_survives_related_node_supersession -- --nocapture
• cargo test -q targeted_evidence_resolves_real_source_not_placeholder -- --nocapture
• cargo test -q test_apply_supersession_manifest_l0_file_change_updates_hash_and_distilled -- --nocapture
• cargo test -q test_set_file_content_hash_preserves_node_ids_order_independent -- --nocapture
• guard list confirmed all five DADBEAR tests are registered:
  • pyramid::dadbear_supervisor::edge_check_apply_tests::edge_survives_endpoint_supersession
  • pyramid::dadbear_supervisor::faq_redistill_apply_tests::faq_link_survives_related_node_supersession
  • pyramid::db::tests::test_set_file_content_hash_preserves_node_ids_order_independent
  • pyramid::prompt_materializer::tests::targeted_evidence_resolves_real_source_not_placeholder
  • pyramid::stale_helpers_upper::tests::test_apply_supersession_manifest_l0_file_change_updates_hash_and_distilled

Draft for PP/Claude gate. No self-merge.