diff --git a/decisions/architecture.md b/decisions/architecture.md
index d4c1cdd74..102e7bd39 100644
--- a/decisions/architecture.md
+++ b/decisions/architecture.md
@@ -1710,6 +1710,8 @@ Technical foundation decisions that constrain implementation: engine, client-ser
 
   **(1) `system_economy.economic_specialization TEXT` (new column).** A 27-value curated vocabulary compiled from `wiki/economics/specialization_vocabulary.toml` into a `specialization_vocabulary` DB table. Each value maps to `(commodity_id, production_ubiquity_override_or_null)` → `(BulkClass, ProductionUbiquity)` for D-233. Scale is encoded in the value (no separate scale column): `breadbasket` pins `ProductionUbiquity = Specialist` where the catalog default would be `Ubiquitous`; `terroir_agriculture` pins `MonopolySource`. Equal-or-higher rule: a `production_ubiquity_override` may only be equal or higher concentration than the commodity's global default (CI hard error V-SES-03). Authored for ~80–100 named systems; deterministic-varied heuristic fallback for ~200 unnamed systems (seed-hashed weighted draw over the vocabulary: W_ROLE_PRIMARY=8,000 bps, W_CORP=5,000 bps, W_NOISE=400 bps to every vocabulary value; same seed+system_id always produces the same value; the noise term ensures ~5–10% of unnamed systems draw an off-primary value, preventing all unnamed agricultural worlds from being identical).
 
+  **Relationship to `economic_base_primary` (the seam — clarified 2026-06-01):** `system_economy.economic_base_primary`/`_secondary` is pre-existing free-text prose (e.g. `"fusion_fuel, financial_services"`) rendered into the wiki index.md "Industries/Exports" infobox by `wiki_sync.py`. `economic_specialization` is a **deliberate parallel representation at higher fidelity**, NOT a duplicate: the prose is uncomputable GTTR flavor for human readers; the enum is the machine-actionable projection the D-233 generator consumes. They are the same *concept* (what the system produces) at two resolutions. The two must stay mutually consistent — `economic_specialization` should never contradict the `economic_base_primary` prose for the same system (the #1016 content pass authors the enum from the same lore the prose describes, and CI soft-warning W-SES-03 flags prose/enum divergence). Unification onto one source was considered and rejected: the prose carries multi-sector nuance and narrative voice the enum cannot, and the enum carries the deterministic (BulkClass × ProductionUbiquity) projection the prose cannot — collapsing either direction loses information. systems.db is canonical; index.md infobox is a read-only DB projection; only the index.md *prose sections* (Supply Dependency / Faction Notes / …, round-tripped by `wiki_sync` `PROSE_SECTIONS`) are authored in-place.
+
   **(2) `system_economy.cultural_specialization TEXT` (new column).** Directs D-232's template pool when a system's cultural character diverges from corridor baseline. Single field carrying two value sub-types: *activity/character values* (`agrarian`, `industrial_heritage`, `institutional`, `scholarly`, `artistic`, `financial_technocratic`, `cosmopolitan`, `compact_cooperative`, etc.) and *heritage-type values* (`scottish`, `vietnamese`, `zulu`, `afrikaans_cape`, `tagalog`, `chinese`, `italian_northern`, `french_provencal`, `norse_compact`, etc.). Heritage values take precedence when both apply. `NULL` = use corridor default (D-232 existing algorithm). Authored for ~60–100 systems where the corridor default would produce wrong D-232 architectural draws in Phase 4 (not a thin Phase 6 concern: a Vietnamese-founded system in the east_reach Korean/Japanese corridor draws the wrong templates without an explicit pin). Does NOT replace `system_culture.cultural_register` (prose NPC/dialogue voice); consumed by the physical generator only.
 
   **(3) `system_factions.dominant_faction TEXT` — populated, not added.** Column already exists (D-199 field 4); VALUES for named systems are authored in this pass via `system_specialization.toml`. 8-value vocabulary: `concord_assembly | compact | compact_sympathetic | syndic_dominant | veil_institute | independent | disputed | mixed`. `lattice_commission` is dropped — the Commission is a regulatory body under Assembly authority, not a governing faction; ACB and Bastion are `concord_assembly`. Authored for ~40–60 named systems; existing Commission-presence + currency-zone derivation serves as fallback.