- HashMap → BTreeMap throughout econ-sim for deterministic iteration (D-010)
- Fix cost_factor: multiplicative gate×zone instead of additive (trade.rs)
- Extract derive_seed to shared prng.rs, consolidate FNV-1a implementation
- Rename run_shock_test → run_no_explosion_check (not D-179 Test 3)
- Deduplicate cross-zone FX rate collection in Test 4
- Replace ORDER BY RANDOM() with deterministic ordering + ChaCha8Rng
- Make commodity coverage failure a hard error consistent with D-175
- Fix gap-fill off-by-one (4 corps → 3 when coverage = 0)
- Correct test report: EconEvent exists, location_type is body/station
All four D-179 stability tests still pass.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Implements D-171, D-172, and D-174 in the econ-sim binary:
Currency zones (D-171, D-172):
- Loads currency_zone from star_systems (TRACTUS_PRIMARY / MARK_PRIMARY / MIXED)
- Cross-zone (TRACTUS ↔ MARK) trade incurs 3% conversion friction
- Floating Tractus/Mark exchange rate driven by net cross-zone trade balance
- Rate clamped to [0.5, 2.0]; ALPHA_FX=0.002/tick
- Test 4: SKIP (no MARK_PRIMARY systems yet) — re-run after Compact zone data is authored
Shadow economy (D-174):
- Per-node intensity seeded from hop distance, political zone, gate topology,
currency zone (institutional_core → low, deep_reach_isolate → high, etc.)
- Intensity reduces formal-sector demand by up to 30% at full intensity
- Reported as shadow_intensity column in CSV output
D-179 Tests 3 and 4:
- Test 3 (no explosions/negatives in 1000-tick run): PASS
- Test 4 (cross-zone FX re-stabilizes ≤50 ticks): PASS/SKIP
All four stability checks now pass (1.05% max dev on convergence, 0.00% drift).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>