test(simulation): lock standalone-HQ-as-ordinary-settlement-row invariant (T-1074)

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

server/src/atlas/attractor_matching.rs

@@ -828,6 +828,76 @@ mod tests {
         assert!(p2.synthetic);
     }
 
+    /// D-242: "hubs are the significant cities, standalone HQs are typically
+    /// minor nodes." `match_cities` has no concept of "corp-originated"
+    /// settlement — a Standalone-HQ CityRecord competes on population/class
+    /// exactly like an ordinary pooled city, so a modest-population HQ must
+    /// NOT out-rank a genuinely major city for the best attractor, and a
+    /// major HQ (large population, or NameLocked) DOES win Tier A on the same
+    /// terms any other settlement would. Both directions verified here.
+    #[test]
+    fn standalone_hq_settlement_competes_on_equal_terms_with_pooled_cities() {
+        let major_city = make_city(1, SettlementClass::PopulationBudget, 5_000_000);
+        // A "minor node" Standalone HQ (D-242's own framing) — modest
+        // population, ordinary PopulationBudget class, nothing marking it as
+        // corp-originated (mirrors populate_standalone_hq_settlements' output
+        // shape: an atlas_city_names row with no corp_id, same as any city).
+        let minor_hq = make_city(2, SettlementClass::PopulationBudget, 80_000);
+        let cities = vec![major_city, minor_hq];
+        let attractors = vec![
+            make_attractor(5, 5, AttractorType::RiverMouth, 95), // best
+            make_attractor(10, 10, AttractorType::ValleyFloor, 30), // worst
+        ];
+        let matrix = uniform_matrix();
+        let placements = match_cities(
+            &cities,
+            &attractors,
+            &matrix,
+            None,
+            512,
+            256,
+            &TerritorialStatus::FrontierUnclaimed,
+            SeedChain::root(42),
+        );
+        let major = placements.iter().find(|p| p.city_id == 1).unwrap();
+        let minor = placements.iter().find(|p| p.city_id == 2).unwrap();
+        assert_eq!(
+            major.position,
+            (5, 5),
+            "the major city (5M pop) must win the best attractor over an 80k-pop HQ"
+        );
+        assert_eq!(
+            minor.position,
+            (10, 10),
+            "the minor HQ gets whatever's left — no special corp-origin priority"
+        );
+
+        // Flip it: a NameLocked HQ (the T-1075 hero-pin path — e.g. "The Gate
+        // Corporation" in the real data) DOES win Tier A, on the same
+        // NameLocked-priority terms as any hero-pinned city (tier_a_gets_priority,
+        // above) — population size never mattered for NameLocked, corp-origin
+        // doesn't add or subtract anything either.
+        let hero_hq = make_city(3, SettlementClass::NameLocked, 200_000);
+        let ordinary_city = make_city(4, SettlementClass::PopulationBudget, 3_000_000);
+        let cities2 = vec![hero_hq, ordinary_city];
+        let placements2 = match_cities(
+            &cities2,
+            &attractors,
+            &matrix,
+            None,
+            512,
+            256,
+            &TerritorialStatus::FrontierUnclaimed,
+            SeedChain::root(42),
+        );
+        let hero = placements2.iter().find(|p| p.city_id == 3).unwrap();
+        assert_eq!(
+            hero.position,
+            (5, 5),
+            "NameLocked HQ wins Tier A over a larger ordinary city — same rule as any NameLocked settlement"
+        );
+    }
+
     #[test]
     fn all_cities_placed() {
         let cities: Vec<CityRecord> = (1..=5)

server/src/atlas/city_context_reader.rs

@@ -1154,6 +1154,50 @@ mod tests {
         );
     }
 
+    // ─── D-242 corp-HQ settlement model (T-1074/T-1075) ──────────────────────
+    //
+    // A Standalone-HQ settlement (economy_import/corporations.py:
+    // populate_standalone_hq_settlements) is inserted into atlas_city_names as
+    // an ORDINARY row — same schema, same fields, no corp linkage marker (the
+    // corp<->settlement relationship lives on corporations.headquarters_body,
+    // not on atlas_city_names). This module's test fixture schema
+    // (make_settlements_db, above) never had a corp_id column to begin with —
+    // this test makes that design invariant explicit: read_body_settlements
+    // (the D-211 placement pipeline's input) cannot distinguish a
+    // corp-Standalone-HQ row from a wiki-pooled city, by construction. If a
+    // future change ever needs to special-case corp-originated settlements,
+    // it will have to be threaded through explicitly — this test fails the
+    // moment that stops being true silently.
+
+    #[test]
+    fn read_body_settlements_treats_standalone_hq_row_identically_to_pooled_city() {
+        // "Gate Corporation" here stands in for a Phase-B-inserted
+        // Standalone-HQ row (name = corp proper_name, economic_role from
+        // corp_hq_placement.toml's standalone_economic_role, population from
+        // the T-1075 Zipf bake, settlement_class from the same bake/override
+        // path as any other city) — indistinguishable in shape from the
+        // ordinary pooled cities "Tributarium"/"Ruhr" it sits alongside.
+        let db = make_settlements_db(&[
+            ("Tributarium", "manufacturing", 2_727_273_224, Some("PopulationBudget")),
+            ("Ruhr", "manufacturing", 1_363_636_611, Some("PopulationBudget")),
+            ("Gate Corporation", "manufacturing", 909_090_165, Some("NameLocked")),
+        ]);
+        let reader = CityContextReader::open(&db).expect("open");
+        let cities = reader.read_body_settlements("PlanetX").expect("read");
+        assert_eq!(cities.len(), 3, "all three rows read back, HQ or not");
+
+        let hq = cities
+            .iter()
+            .find(|c| c.name == "Gate Corporation")
+            .expect("Standalone-HQ row must be present");
+        // Every CityRecord field the D-211 pipeline reads is populated exactly
+        // like an ordinary city's — nothing marks this row as corp-originated.
+        assert_eq!(hq.economic_role, "manufacturing");
+        assert_eq!(hq.population, 909_090_165);
+        assert_eq!(hq.settlement_class, SettlementClass::NameLocked);
+        assert!(!hq.is_capital, "Standalone HQ is not a capital by default");
+    }
+
     // ─── read_body_city_names (T-949) ────────────────────────────────────────
 
     #[test]