feat: TECHNICAL_PLACEHOLDER (NCM 00000000) is replaceable by the product enrichment; real values preserved; Agent 1.3.4

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

docs/product_enrichment.md

@@ -107,3 +107,13 @@ Production KB starts empty (0 products, head 0028 before deploy). The lab databa
 
 ### Measured (local data only; `docs/runs/enrichment_history_analysis.json`)
 See the V2 report in the mission summary; key findings: cross-client NCM agreement is poor (a candidate taken from the other clients matches the held-out client's own NCM only 62 % of the time, and only 42 % even when >= 2 clients corroborate it), which is exactly why client data can never verify an NCM on its own.
+
+
+## TECHNICAL_PLACEHOLDER (1.3.4)
+The SGV refuses to save a product without NCM, so operators type a filler. An empty-only rule therefore never fires for that product. Contract:
+- Per-field allowlist `PRODUCT_ENRICHMENT_PLACEHOLDERS = {CLASSIFICACAO_FISCAL: {"00000000"}}` (dots ignored: `0000.00.00` is the same filler). `0`, `99999999`, `SEM NCM`... are NOT placeholders (no evidence of SGV behaviour); nothing else is ever overwritten.
+- A placeholder is "not classified yet", never `HUMAN_OVERRIDDEN`. A real NCM (even a wrong one) is preserved, whatever the KB says. cClassTrib typed by the operator is never touched (RTC gates own it).
+- Where it is decided: the Hub treats a placeholder like an empty field when it builds the per-field decisions (`resolver._empty`, audit note `technical_placeholder`); the Agent must ALSO accept it in the typed write (`write_field`: compare-and-swap `UPDATE ... WHERE TRIM(f)=<exact value just read>`), so this needs Agent >= 1.3.4.
+  Both tables are identical (parity test). The audit records `old = 00000000`.
+- Scope reminders: products created while the function was DISABLED / WAITING stay history (re-baseline); REPROCESS_ALL/SYNC do not push products through the enrichment (only NEW products after the baseline do);
+  a product WITHOUT EAN is resolved by name only from a unique VERIFIED_KB match.

docs/runs/enrichment_placeholder_e2e.json

@@ -0,0 +1,22 @@
+{
+ "copy_only": true,
+ "checks": {
+  "PLACEHOLDER_PRODUCT_DETECTED_DRY_RUN": true,
+  "DRY_RUN_ZERO_WRITES": true,
+  "DRY_RUN_DECISION_GENERATED_FOR_NCM": true,
+  "ENABLED_PLACEHOLDER_REPLACED": true,
+  "CEST_IPI_ONLY_WHEN_SAFE": true,
+  "CCLASSTRIB_OPERATOR_VALUE_UNTOUCHED": true,
+  "AUDIT_RECORDS_THE_REPLACED_PLACEHOLDER": true,
+  "EXISTING_REAL_VALUE_PRESERVED": true,
+  "UNLISTED_FILLER_NOT_OVERWRITTEN": true,
+  "SECOND_RUN_WRITES_0": true
+ },
+ "ALL_PASS": true,
+ "PH002": [
+  "22021000",
+  "0300700",
+  0.0,
+  "200009"
+ ]
+}