fix: product_role never infers OWN_PRODUCTION from a single COMPOSICAO occurrence

Missão 4 / Bloco A.1 (prioridade máxima): central.app.field_contract.infer_role
treated ANY C000032.TIPO=COMPOSICAO row for a product as proof of own
production, with no ratio check - a beer sold 19 times and used once as a
recipe component (Agent 2, real data) was classified OWN_PRODUCTION from
that single occurrence, proposing to change its CFOP and IPPT.

New deterministic threshold in field_contract.py: COMPOSICAO must be a
majority (>=70%) of that product's own C000032 movement history, with at
least 5 total events, to count as own-production evidence. Below 30% the
evidence is discarded entirely (falls through to other role evidence,
e.g. TIPO=VENDA -> RESALE). Between 30% and 70% (with enough events to be
meaningful) is genuinely conflicting evidence -> UNKNOWN, never guessed
either way. RECEITA_INGREDIENTES/PROD_COZINHA-based evidence (a direct
recipe-table linkage, not a statistical ratio) is untouched.

agent/src/gti_fiscal_agent/firebird_reader.py now counts COMPOSICAO vs other
C000032 rows per product (read_product_evidence: single indexed query;
read_evidence: one grouped query for the whole catalog) into a new
ev["composed_ratio"] key, alongside the existing "composed" set (kept for
other, non-role consumers like coverage.py). central/app/enrichment/api.py's
sanitize_product_evidence and fiscal_completion.py's empty-ev fallback both
carry the new key through.

New tests (central/tests/test_field_contract.py) cover the 5 real cases named
in the mission: the beer (1 vs 19, 5% - discarded), a second beer (3 vs 4,
42.9% - MIXED/UNKNOWN), the liqueur (34 vs 22, 60.7% - still MIXED/UNKNOWN,
below the 70% bar), the juice with PROD_COZINHA=1+RECEITA_INGREDIENTES
(unaffected, stays OWN_PRODUCTION), and the tilapia/corvina fish (no
composed evidence at all, stays RESALE) - plus a strong 90% majority case
and an insufficient-sample (<5 events) case. A new end-to-end test in
agent/tests/test_cfop_ippt_auto_apply.py (committed separately, see the
feature/cfop-ippt-write branch) proves the weak-evidence beer never reaches
select_candidates as a write candidate, independent of any write flag.

Re-running the dry-run over Agent 2's real database (GTI.FDB, 527 products)
after this fix: AUTO_FILL_SAFE CFOP/IPPT cells drop from 12 to 3 (the two
fish CFOP fills + the juice's IPPT, all with strong, non-statistical
evidence) - docs/runs/GTI_dryrun_universe_summary_after_A1.json. This
corrects the Missão 3 report's 12/9(downgraded)/4(sustained) manual
judgment call with a deterministic, tested engine rule.

No schema/migration change. Zero Firebird writes (read-only analysis only).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

central/tests/test_field_contract.py

@@ -221,6 +221,47 @@ def test_role_inference_is_evidence_based_and_conflicts_stay_unknown():
     assert infer_role(product(PROD_COZINHA=1), {**EV, "recipes": {"000001"}}, Context([]), "000001", "1")[0] == "OWN_PRODUCTION"
 
 
+def test_composed_evidence_needs_a_dominant_majority_never_a_single_occurrence():
+    """Missão 4 / Bloco A.1: C000032.TIPO=COMPOSICAO must be a deterministic MAJORITY of that
+    product's own movement history to prove OWN_PRODUCTION - real cases audited from Agent 2 (2026-09-28)."""
+    def ev_with(composed, other):
+        return {**EV, "composed_ratio": {"000001": {"composed": composed, "other": other}}}
+
+    # A cerveja: 1 composição vs 19 vendas (5%) - minoria clara, evidência descartada -> cai para o
+    # papel padrão (aqui sem TIPO=VENDA/docs no fixture, então UNKNOWN por falta de outra evidência;
+    # o ponto do teste é que NUNCA vira OWN_PRODUCTION).
+    assert infer_role(product(), ev_with(1, 19), Context([]), "000001", "1")[0] != "OWN_PRODUCTION"
+    r = infer_role(product(TIPO="VENDA"), {**ev_with(1, 19), "stock_in": {"000001": True}}, Context([]), "000001", "1")
+    assert r[0] == "RESALE"  # a cerveja, com evidência de venda, é revenda - nunca produção própria
+
+    # O refrigerante/2ª cerveja: 3 composições vs 4 vendas (42,9%) - amostra pequena mas na zona
+    # ambígua -> evidência CONFLITANTE, nunca adivinhada para nenhum dos dois lados.
+    r = infer_role(product(TIPO="VENDA"), {**ev_with(3, 4), "stock_in": {"000001": True}}, Context([]), "000001", "1")
+    assert r[0] == "UNKNOWN" and "MIXED" in r[1][0]
+
+    # O licor: 34 composições vs 22 vendas (60,7%) - maioria real, mas abaixo do limiar dominante
+    # (70%) -> também CONFLITANTE, nunca OWN_PRODUCTION por uma maioria fraca.
+    r = infer_role(product(TIPO="VENDA"), {**ev_with(34, 22), "stock_in": {"000001": True}}, Context([]), "000001", "1")
+    assert r[0] == "UNKNOWN" and "MIXED" in r[1][0]
+
+    # Suco com PROD_COZINHA=1 + RECEITA_INGREDIENTES: evidência forte e DIRETA (não é composição
+    # estatística) - continua OWN_PRODUCTION, o limiar de composição não se aplica a ela.
+    assert infer_role(product(PROD_COZINHA=1), {**EV, "recipes": {"000001"}}, Context([]), "000001", "1")[0] == "OWN_PRODUCTION"
+
+    # Uma maioria REAL e forte (90%, amostra suficiente) ainda prova produção própria.
+    r = infer_role(product(), ev_with(90, 10), Context([]), "000001", "1")
+    assert r[0] == "OWN_PRODUCTION" and r[1] == ["C000032.TIPO=COMPOSICAO"]
+
+    # Amostra insuficiente (< 5 eventos), mesmo 100% composição: não confia num histórico tão raso.
+    r = infer_role(product(TIPO="VENDA"), {**ev_with(2, 0), "stock_in": {"000001": True}}, Context([]), "000001", "1")
+    assert r[0] == "RESALE"  # a evidência de composição é ignorada, cai para a evidência de venda real
+
+    # Tilápia/corvina: sem NENHUMA evidência de composição - continua revenda normalmente (o fix
+    # não pode quebrar o caso que já funcionava).
+    r = infer_role(product(TIPO="VENDA", CFOP=None), {**EV, "purchases": {"000001": [{}]}}, Context([]), "000001", "1")
+    assert r[0] == "RESALE"
+
+
 # ---------------- executor guards ----------------
 def load_executor():
     spec = importlib.util.spec_from_file_location("fwe_local", ROOT / "scripts" / "firebird_write_executor.py")