feat(s54): value_report roll-up builder over SavingsLedger accessors

src/portfolio_optimiser/value_report.py

@@ -0,0 +1,84 @@
+"""S5.4 — verdirapport (målbilde §7): read-only savings roll-up over SavingsLedger.
+
+MAF-bound via ``ledger`` (which imports the MAF-bound ``verdicts``), so this module CANNOT live in
+the framework-neutral ``shared/`` subtree and is deliberately NOT registered in
+``tests/test_okf.py``'s ``_MAF_FREE_MODULES``. It is a pure OFFLINE read: it turns the ledger's
+already-deduped integer-øre totals into a legible statement of value (per-project + portfolio
+totals, flagged cross-dimension overlaps, per-entry provenance). Zero model calls, zero writes.
+
+Correctness rests on CALLING the ledger's roll-up accessors (``per_project_total`` /
+``portfolio_total`` / ``overlaps``) — never re-summing ``.entries``, which would double-count a
+saving realized under two dimensions (the exact bug the ledger's dimension-free dedup prevents).
+"""
+
+from __future__ import annotations
+
+from pydantic import BaseModel
+
+from portfolio_optimiser.ledger import SavingsLedger
+
+
+class ProvenanceLine(BaseModel):
+    """One realized ledger entry surfaced at the report's ENTRY level: verbatim ``verdict_id`` +
+    ``provenance`` string kept in association, so provenance is legible per-entry in the JSON
+    output. Reads ONLY the entry's own fields — never joins the MAF verdict store (Non-Goal)."""
+
+    project_id: str
+    dimension: str
+    candidate_identity: str
+    verdict_id: str
+    amount_ore: int
+    provenance: str
+
+
+class ValueReport(BaseModel):
+    """The read-only value roll-up over a ``SavingsLedger``: per-project + portfolio totals (integer
+    øre, dimension-free-deduped by the ledger accessors), the flagged cross-dimension ``overlaps``,
+    and one ``ProvenanceLine`` per ledger entry (deterministically ordered)."""
+
+    per_project: dict[str, int]
+    portfolio_total_ore: int
+    overlaps: list[tuple[str, str]]
+    provenance: list[ProvenanceLine]
+
+
+def build_value_report(ledger: SavingsLedger) -> ValueReport:
+    """Build the value report by CALLING the ledger's deduped roll-up accessors — never summing
+    ``.entries`` directly (double-count risk on cross-dimension overlaps).
+
+    The provenance sort key is TOTAL: the leading ``(project_id, dimension, candidate_identity)``
+    triple is the ledger's ``_storage_key``, unique for in-process-built ledgers but NOT for a
+    ``load()``-ed / hand-authored file (load does no dedup), so two rows sharing the triple would tie
+    and their order would follow file insertion order (byte-instability). Appending
+    ``verdict_id, provenance, amount_ore`` makes the order total and byte-stable (SC6).
+    """
+    project_ids = sorted({e.project_id for e in ledger.entries})
+    per_project = {pid: ledger.per_project_total(pid) for pid in project_ids}
+    ordered_entries = sorted(
+        ledger.entries,
+        key=lambda e: (
+            e.project_id,
+            e.dimension,
+            e.candidate_identity,
+            e.verdict_id,
+            e.provenance,
+            e.amount_ore,
+        ),
+    )
+    provenance = [
+        ProvenanceLine(
+            project_id=e.project_id,
+            dimension=e.dimension,
+            candidate_identity=e.candidate_identity,
+            verdict_id=e.verdict_id,
+            amount_ore=e.amount_ore,
+            provenance=e.provenance,
+        )
+        for e in ordered_entries
+    ]
+    return ValueReport(
+        per_project=per_project,
+        portfolio_total_ore=ledger.portfolio_total(),
+        overlaps=ledger.overlaps(),
+        provenance=provenance,
+    )