feat: reporting-allocate AI-plan cost across work

Split a booked AI-plan fact across workplans or repos using measured
tokens, measured+estimated tokens, session counts, or an even split.
Unmeasured remainder stays a residual. The record is not resource-control
AllocationEvidence and does not create booked spend.

tests/test_reporting_allocation.py

@@ -0,0 +1,98 @@
+import sqlite3
+from decimal import Decimal
+from pathlib import Path
+
+import pytest
+
+from fin_hub.services.allocation import shared_cost_allocations
+from fin_hub.services.exchange import ingest_planning_evidence
+from fin_hub.services.ledger import import_csv, monthly_summary
+from fin_hub.services.reporting_allocation import (
+    allocate_ai_plan_report,
+    list_ai_plan_allocations,
+)
+from fin_hub.services.session_tokens import ingest_session_token_file
+
+FIXTURES = Path(__file__).parent / "fixtures"
+
+
+def _claude_fact(tmp_path: Path) -> tuple[Path, str]:
+    ledger = tmp_path / "ledger.db"
+    import_csv(FIXTURES / "ai-plans.csv", "ai-plan", ledger_path=ledger)
+    with sqlite3.connect(ledger) as conn:
+        fact_id = conn.execute(
+            "SELECT financial_fact_id FROM ledger_entries "
+            "WHERE source_type = 'ai-plan' AND label = 'claude-max' AND is_current = 1"
+        ).fetchone()[0]
+    return ledger, fact_id
+
+
+def test_measured_token_share_two_workplans_keeps_unmeasured_residual(tmp_path: Path):
+    ledger, fact_id = _claude_fact(tmp_path)
+    ingest_session_token_file(
+        FIXTURES / "session-tokens-two-workplans.json", ledger_path=ledger
+    )
+    report = allocate_ai_plan_report(
+        fact_id, method="measured_token_share", ledger_path=ledger
+    )
+    by_key = {target.target_key: target for target in report.targets}
+    assert report.booked_amount == Decimal("200.00")
+    assert report.method == "measured_token_share"
+    assert report.residual_reason == "unmeasured"
+    assert report.residual_share == Decimal("0.25")
+    assert report.residual_amount == Decimal("50.00")
+    assert by_key["workplan:workplan-a"].amount == Decimal("100.00")
+    assert by_key["workplan:workplan-b"].amount == Decimal("50.00")
+    assert sum((target.amount for target in report.targets), report.residual_amount) == Decimal(
+        "200.00"
+    )
+    assert monthly_summary(ledger_path=ledger)[0].total == pytest.approx(240.0)
+    assert shared_cost_allocations(ledger_path=ledger) == []
+    assert list_ai_plan_allocations(ledger_path=ledger)[0].record_id == report.record_id
+
+
+def test_even_split_does_not_use_token_weights(tmp_path: Path):
+    ledger, fact_id = _claude_fact(tmp_path)
+    ingest_session_token_file(
+        FIXTURES / "session-tokens-two-workplans.json", ledger_path=ledger
+    )
+    report = allocate_ai_plan_report(fact_id, method="even_split", ledger_path=ledger)
+    amounts = sorted(target.amount for target in report.targets)
+    assert amounts == [Decimal("100.00"), Decimal("100.00")]
+    assert report.residual_share == Decimal("0.00")
+    assert report.residual_reason == "none"
+
+
+def test_reporting_allocation_is_not_planning_allocation(tmp_path: Path):
+    ledger, fact_id = _claude_fact(tmp_path)
+    report = allocate_ai_plan_report(fact_id, method="even_split", ledger_path=ledger)
+    with pytest.raises(ValueError, match="not resource-control"):
+        ingest_planning_evidence(
+            {
+                "record_type": "reporting_allocation",
+                "record_id": report.record_id,
+                "financial_fact_id": fact_id,
+                "method": "even_split",
+            },
+            ledger_path=ledger,
+        )
+    with sqlite3.connect(ledger) as conn:
+        planning = conn.execute(
+            "SELECT count(*) FROM sqlite_master WHERE name = 'planning_evidence'"
+        ).fetchone()[0]
+        if planning:
+            stored = conn.execute(
+                "SELECT record_type FROM planning_evidence"
+            ).fetchall()
+            assert stored == []
+
+
+def test_non_ai_plan_fact_is_rejected(tmp_path: Path):
+    ledger = tmp_path / "ledger.db"
+    import_csv(FIXTURES / "cloud-costs.csv", "cloud", ledger_path=ledger)
+    with sqlite3.connect(ledger) as conn:
+        fact_id = conn.execute(
+            "SELECT financial_fact_id FROM ledger_entries WHERE is_current = 1"
+        ).fetchone()[0]
+    with pytest.raises(ValueError, match="ai-plan"):
+        allocate_ai_plan_report(fact_id, method="even_split", ledger_path=ledger)