02 — Branch B: PREFIX-NNN / meta_catalog Code Assignment Plan (B-3 CLOSED)

Where the code rule actually lives

There is no central prefix-registry table. The PREFIX-NNN rule is enforced in exactly one place:

• fn_pre_birth_check Check 3: IF p_code ~ '^[A-Z]+-[0-9]+$' → pass. (Verified live, full body captured.)
• fn_birth_gate runs the 5 checks; default mode is warning (app.birth_gate_mode is unset in dot_config), so a bad code warns but does not block — which is why "đẻ rơi" raw inserts are technically possible and forbidden by law, not by trigger.

The family prefix is documented (not enforced) via entity_species.prefix (FIELD/FORM/TIER). So "registering the prefix" = setting entity_species.prefix + using a conforming collection_registry.code.

meta_catalog code path

• gen_code_meta_catalog (BEFORE INSERT) auto-assigns CAT-<lpad(nextval('seq_meta_catalog_code'),3)> only when code is empty. If you supply an explicit code it is kept (proven: prior rehearsals' explicit CAT-1011 was not overridden).
• meta_catalog.code has no UNIQUE constraint (0 unique constraints live). A collision will not raise but will break fn_pre_birth_check Check 5 logic downstream — so codes must be chosen collision-free.
• Live max(CAT-NNN number) = 1010. → CAT-1011, CAT-1012, CAT-1013 are free.

Exact code assignment (activation-ready)

Registry	collection_registry.code	meta_catalog.code	entity_species.code	entity_species.species_code	entity_species.prefix
field_registry	FIELD-001	CAT-1011	SPC-FIELD-001	field_registry_species	FIELD
input_form_registry	FORM-001	CAT-1012	SPC-FORM-001	input_form_registry_species	FORM
tier_registry	TIER-001	CAT-1013	SPC-TIER-001	tier_registry_species	TIER

All three FIELD-001/FORM-001/TIER-001 match ^[A-Z]+-[0-9]+$ → Check 3 PASS (proven live, doc 05). Decision: supply explicit CAT codes (not empty) for determinism and to avoid sequence drift, matching the proven rehearsal.

Pre-commit collision-avoidance / validation query

Run as workflow_admin immediately before commit; every row must return 0 / free:

SELECT
  (SELECT count(*) FROM meta_catalog        WHERE code IN ('CAT-1011','CAT-1012','CAT-1013'))                         AS meta_code_taken,        -- expect 0
  (SELECT count(*) FROM collection_registry WHERE code IN ('FIELD-001','FORM-001','TIER-001'))                       AS coll_code_taken,        -- expect 0
  (SELECT count(*) FROM entity_species      WHERE code IN ('SPC-FIELD-001','SPC-FORM-001','SPC-TIER-001'))           AS species_code_taken,     -- expect 0
  (SELECT count(*) FROM entity_species      WHERE species_code IN ('field_registry_species','input_form_registry_species','tier_registry_species')) AS species_key_taken, -- expect 0
  (SELECT max((regexp_replace(code,'\D','','g'))::int) FROM meta_catalog WHERE code ~ '^CAT-[0-9]+$')                AS max_cat_num,            -- expect 1010
  bool_and('FIELD-001' ~ '^[A-Z]+-[0-9]+$' AND 'FORM-001' ~ '^[A-Z]+-[0-9]+$' AND 'TIER-001' ~ '^[A-Z]+-[0-9]+$')   AS codes_format_ok;        -- expect t

If max_cat_num has advanced past 1010 at commit time, bump the three CAT codes to CAT-<max+1..+3> accordingly (the activation pack, doc 06, computes them dynamically as a safety net).

Rollback impact

Codes are plain column values; rollback is trivial (rows removed in-tx or via retire/delete). No sequence is consumed when codes are supplied explicitly (gen_code skips nextval), so there is no sequence-drift side effect from a rolled-back or retired birth — a deliberate advantage of the explicit-code path.