feat: book monthly AI-plan invoices as facts and commitments

Add ai-plan ingest that stores one current booked fact per
provider-account × plan × period. Subscriptions become recurring
commitments; usage top-ups do not. Session-level rows are rejected.

tests/fixtures/ai-plans.csv

@@ -0,0 +1,3 @@
+provider,provider_account,plan,charge_kind,amount,currency,period_month,ongoing
+anthropic,,claude-max,subscription,200.00,EUR,2026-08,true
+openai,org-demo,api-prepaid,usage_topup,40.00,EUR,2026-08,false

tests/test_ai_plan.py

@@ -0,0 +1,147 @@
+from pathlib import Path
+
+import pytest
+
+from fin_hub.ingest.ai_plan import parse_ai_plan_csv
+from fin_hub.services.evaluate import evaluate_runway
+from fin_hub.services.exchange import booked_cost_projection
+from fin_hub.services.ledger import (
+    import_csv,
+    list_current_commitments,
+    monthly_summary,
+    set_opening_balance,
+)
+
+FIXTURES = Path(__file__).parent / "fixtures"
+
+
+def test_parse_ai_plan_fixture_keeps_subscription_and_topup_separate():
+    rows = parse_ai_plan_csv(FIXTURES / "ai-plans.csv")
+    assert len(rows) == 2
+    assert rows[0].provider == "anthropic"
+    assert rows[0].charge_kind == "subscription"
+    assert rows[0].ongoing is True
+    assert rows[0].provider_account is None
+    assert rows[1].provider == "openai"
+    assert rows[1].charge_kind == "usage_topup"
+    assert rows[1].ongoing is False
+    assert rows[1].provider_account == "org-demo"
+    assert rows[0].incurred_on.isoformat() == "2026-08-01"
+
+
+def test_parse_ai_plan_rejects_session_level_rows(tmp_path: Path):
+    source = tmp_path / "sessions.csv"
+    source.write_text(
+        "provider,plan,charge_kind,amount,currency,period_month,session_id\n"
+        "anthropic,claude-max,subscription,200.00,EUR,2026-08,sess-1\n",
+        encoding="utf-8",
+    )
+    with pytest.raises(ValueError, match="session-level"):
+        parse_ai_plan_csv(source)
+
+
+def test_import_ai_plans_books_once_and_commits_only_subscriptions(tmp_path: Path):
+    ledger = tmp_path / "ledger.db"
+    first = import_csv(FIXTURES / "ai-plans.csv", "ai-plan", ledger_path=ledger)
+    second = import_csv(FIXTURES / "ai-plans.csv", "ai-plan", ledger_path=ledger)
+    assert first.rows_imported == 2
+    assert second.skipped is True
+
+    rollup = monthly_summary(ledger_path=ledger)[0]
+    assert rollup.currency == "EUR"
+    assert rollup.period_month == "2026-08"
+    assert rollup.total == pytest.approx(240.0)
+    assert rollup.entry_count == 2
+
+    commitments = list_current_commitments(ledger_path=ledger)
+    assert len(commitments) == 1
+    assert commitments[0].provider == "anthropic"
+    assert commitments[0].plan == "claude-max"
+    assert commitments[0].amount == 200
+    assert commitments[0].financial_fact_id is not None
+
+
+def test_ai_plan_correction_is_append_only(tmp_path: Path):
+    ledger = tmp_path / "ledger.db"
+    source = tmp_path / "plans.csv"
+    source.write_text(
+        "provider,plan,charge_kind,amount,currency,period_month,ongoing\n"
+        "anthropic,claude-max,subscription,200.00,EUR,2026-08,true\n",
+        encoding="utf-8",
+    )
+    import_csv(source, "ai-plan", ledger_path=ledger)
+    source.write_text(
+        "provider,plan,charge_kind,amount,currency,period_month,ongoing\n"
+        "anthropic,claude-max,subscription,220.00,EUR,2026-08,true\n",
+        encoding="utf-8",
+    )
+    with pytest.raises(ValueError, match="explicit correction"):
+        import_csv(source, "ai-plan", ledger_path=ledger)
+    corrected = import_csv(source, "ai-plan", ledger_path=ledger, force=True)
+    assert corrected.rows_imported == 1
+    assert monthly_summary(ledger_path=ledger)[0].total == pytest.approx(220.0)
+    commitments = list_current_commitments(ledger_path=ledger)
+    assert len(commitments) == 1
+    assert commitments[0].amount == 220
+    assert commitments[0].revision_of is not None
+
+
+def test_ending_a_subscription_closes_the_commitment(tmp_path: Path):
+    ledger = tmp_path / "ledger.db"
+    source = tmp_path / "plans.csv"
+    source.write_text(
+        "provider,plan,charge_kind,amount,currency,period_month,ongoing\n"
+        "anthropic,claude-max,subscription,200.00,EUR,2026-08,true\n",
+        encoding="utf-8",
+    )
+    import_csv(source, "ai-plan", ledger_path=ledger)
+    source.write_text(
+        "provider,plan,charge_kind,amount,currency,period_month,ongoing\n"
+        "anthropic,claude-max,subscription,200.00,EUR,2026-09,false\n",
+        encoding="utf-8",
+    )
+    import_csv(source, "ai-plan", ledger_path=ledger)
+    assert list_current_commitments(ledger_path=ledger) == []
+    months = {row.period_month: row.total for row in monthly_summary(ledger_path=ledger)}
+    assert months["2026-08"] == pytest.approx(200.0)
+    assert months["2026-09"] == pytest.approx(200.0)
+
+
+def test_ai_plan_facts_project_without_invented_resource_id(tmp_path: Path):
+    ledger = tmp_path / "ledger.db"
+    import_csv(FIXTURES / "ai-plans.csv", "ai-plan", ledger_path=ledger)
+    facts = booked_cost_projection(ledger_path=ledger)
+    by_provider = {fact.provider: fact for fact in facts}
+    assert set(by_provider) == {"anthropic", "openai"}
+    assert by_provider["anthropic"].service_id == "claude-max"
+    assert by_provider["anthropic"].resource_id is None
+    assert by_provider["anthropic"].tax_status == "unknown"
+    assert by_provider["openai"].service_id == "api-prepaid"
+    assert by_provider["openai"].effective_amount == 40
+
+
+def test_ai_plan_commitment_appears_on_runway_when_no_other_burns(tmp_path: Path):
+    ledger = tmp_path / "ledger.db"
+    set_opening_balance(ledger, 12000.0, currency="EUR")
+    source = tmp_path / "future-only.csv"
+    source.write_text(
+        "provider,plan,charge_kind,amount,currency,period_month,ongoing\n"
+        "xai,grok-heavy,subscription,300.00,USD,2026-09,true\n",
+        encoding="utf-8",
+    )
+    import_csv(source, "ai-plan", ledger_path=ledger)
+    empty_eur = evaluate_runway(ledger_path=ledger, currency="EUR")
+    assert empty_eur["commitments"] == []
+    usd = evaluate_runway(ledger_path=ledger, currency="USD")
+    assert usd["runway"]["monthly_burn"] == pytest.approx(300.0)
+    assert usd["commitments"][0]["plan"] == "grok-heavy"
+
+
+def test_booked_ai_plan_invoices_drive_runway_without_double_counting(tmp_path: Path):
+    ledger = tmp_path / "ledger.db"
+    set_opening_balance(ledger, 12000.0)
+    import_csv(FIXTURES / "ai-plans.csv", "ai-plan", ledger_path=ledger)
+    report = evaluate_runway(ledger_path=ledger)
+    assert report["runway"]["monthly_burn"] == pytest.approx(240.0)
+    assert len(report["commitments"]) == 1
+    assert report["commitments"][0]["amount"] == 200