Fix cumulative platform cost Stripe double-counting

Split infrastructure vs payment-processing costs. Liquidity burn now
uses infrastructure cash out only (€1,155.20 cumulative) because Stripe
fees are already deducted from net member payments. Total platform cost
(€1,158.24) remains visible for gross-margin economics.

projects/coulomb-pricing/tests/test_economics.py

@@ -27,19 +27,16 @@ def test_active_members_counts_only_active_status() -> None:
     assert active_members(members) == 1
 
 
-def test_rate_card_matches_documented_platform_cost_without_revenue() -> None:
+def test_rate_card_splits_infrastructure_and_payment_processing() -> None:
     rate_card, fx_rates = load_cost_rate_card(DATA_DIR)
-    total = monthly_cost_from_rate_card(rate_card, fx_rates, Decimal("0"), 0)
-    assert total == Decimal("72.20")
+    infrastructure = monthly_cost_from_rate_card(rate_card, fx_rates, Decimal("0"), 0)
+    with_revenue = monthly_cost_from_rate_card(rate_card, fx_rates, Decimal("8.99"), 1)
+    assert infrastructure == Decimal("72.20")
+    assert with_revenue == Decimal("72.58")
+    assert with_revenue - infrastructure == Decimal("0.38")
 
 
-def test_rate_card_matches_platform_cost_with_one_member() -> None:
-    rate_card, fx_rates = load_cost_rate_card(DATA_DIR)
-    total = monthly_cost_from_rate_card(rate_card, fx_rates, Decimal("8.99"), 1)
-    assert total == Decimal("72.58")
-
-
-def test_build_snapshot_june_2026_shows_liquidity_burn() -> None:
+def test_build_snapshot_june_2026_avoids_stripe_double_count_in_liquidity() -> None:
     product = load_product(DATA_DIR)
     models = load_pricing_models(DATA_DIR)
     members = load_membership(DATA_DIR)
@@ -48,37 +45,34 @@ def test_build_snapshot_june_2026_shows_liquidity_burn() -> None:
 
     snapshot = build_snapshot("2026-06", product, models, members, revenue, monthly_costs)
 
-    assert snapshot.active_members == 1
-    assert snapshot.monthly_revenue == Decimal("8.99")
-    assert snapshot.monthly_platform_cost == Decimal("72.58")
-    assert snapshot.period_net_liquidity == Decimal("-63.97")
-    assert snapshot.liquidity_status == "burning"
+    assert snapshot.monthly_infrastructure_cost == Decimal("72.20")
+    assert snapshot.monthly_payment_processing_cost == Decimal("0.38")
+    assert snapshot.monthly_total_platform_cost == Decimal("72.58")
+    assert snapshot.period_net_liquidity == Decimal("-63.59")
     assert snapshot.gross_margin == Decimal("-63.59")
 
 
-def test_liquidity_summary_tracks_budget_burn_through_june_2026() -> None:
+def test_liquidity_summary_uses_infrastructure_only_for_cumulative_burn() -> None:
     budget = load_budget(DATA_DIR)
     revenue = load_revenue(DATA_DIR)
     monthly_costs = load_monthly_platform_costs(DATA_DIR)
 
     summary = build_liquidity_summary(budget, revenue, monthly_costs, "2026-06")
 
-    assert summary.initial_budget == Decimal("1000.00")
-    assert summary.cumulative_platform_cost == Decimal("1158.24")
+    assert summary.cumulative_infrastructure_cost == Decimal("1155.20")
+    assert summary.cumulative_payment_processing_cost == Decimal("3.04")
+    assert summary.cumulative_total_platform_cost == Decimal("1158.24")
     assert summary.cumulative_member_payments == Decimal("68.88")
-    assert summary.cumulative_net_liquidity == Decimal("-1089.36")
-    assert summary.remaining_budget == Decimal("-89.36")
+    assert summary.cumulative_net_liquidity == Decimal("-1086.32")
+    assert summary.remaining_budget == Decimal("-86.32")
     assert summary.liquidity_status == "burning"
     assert summary.months_tracked == 16
 
 
-def test_dashboard_renders_liquidity_sections() -> None:
+def test_dashboard_renders_split_cost_columns() -> None:
     from observatory.dashboard import generate_dashboard
 
     report = generate_dashboard(DATA_DIR, "2026-06")
-    assert "Liquidity & Budget" in report
-    assert "Monthly History" in report
-    assert "2025-03" in report
-    assert "2025-11" in report
-    assert "remaining budget" not in report.lower() or "Remaining budget" in report
-    assert "-89.36" in report
+    assert "Cumulative infrastructure cost" in report
+    assert "1155.20" in report
+    assert "-86.32" in report