feat(fase2a): MAF-fri outbox.py — byte-deterministisk proposal/outcome-writer (S2.1)

src/portfolio_optimiser/outbox.py

@@ -0,0 +1,93 @@
+"""RAW output layer (Fase 2a, S2.1 · målbilde §3, R2): byte-deterministic outbox writer.
+
+After a run, ``write_outbox`` persists two JSON artefacts — ``{run_id}-proposal.json`` (the candidate
+IR + its provenance stamp) and ``{run_id}-outcome.json`` (the validated Monte-Carlo percentiles OR
+the rejection reason, plus the checker verdict + the captured verdict id). This is the traceable
+output layer Fase 5 (S5.1/S5.4) consumes; it is the OUTBOX, distinct from the async verdict INBOX
+(``verdict_dir``) — a run must never write its outbox into a folder it also reads as an inbox
+(that would bypass the Step-8 promotion gate; see ``run_project``'s docstring).
+
+**MAF-free** (D7-portable): pure stdlib plus the MAF-free ``validator`` leaf for the outcome
+``isinstance`` branch. ``ProvenanceStamp`` is imported ONLY under ``TYPE_CHECKING`` and serialized
+duck-typed via ``.model_dump()`` — so importing this module never pulls in ``agent_framework``.
+Registered in ``tests/test_okf.py``'s ``_MAF_FREE_MODULES`` and enforced by ``test_okf_is_maf_free``
+(which proves no DIRECT ``agent_framework``/``mcp`` import — MAF-freedom otherwise holds by
+construction, since only the MAF-free ``validator`` is imported at runtime).
+
+Byte-determinism: ``json.dumps(payload, sort_keys=True, indent=2)`` + explicit trailing ``\\n`` +
+UTF-8, and the caller supplies ``run_id`` (no wall-clock / uuid default) — so two runs with identical
+input produce byte-identical files (diff-stable, mirrors ``verdicts.write_verdict`` /
+``ledger.SavingsLedger.save``).
+
+Deliberately NOT exported in ``portfolio_optimiser.__all__``: this is an internal wiring primitive
+called by ``run_project``, not a public authoring API (contrast ``verdicts.write_verdict``).
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+from typing import TYPE_CHECKING, Any
+
+from portfolio_optimiser.validator import Rejection, ValidatedProposal
+
+if TYPE_CHECKING:  # provenance imports agent_framework — keep it out of the runtime import graph
+    from portfolio_optimiser.provenance import ProvenanceStamp
+
+
+def _dump(payload: dict[str, Any]) -> str:
+    """Byte-deterministic on-disk form: sorted keys, 2-space indent, explicit trailing newline."""
+    return json.dumps(payload, sort_keys=True, indent=2) + "\n"
+
+
+def write_outbox(
+    outbox_dir: str,
+    run_id: str,
+    *,
+    outcome: ValidatedProposal | Rejection,
+    provenance: ProvenanceStamp,
+    checker_verdict: str | None,
+    verdict_id: str,
+) -> tuple[Path, Path]:
+    """Write ``{run_id}-proposal.json`` + ``{run_id}-outcome.json`` into ``outbox_dir`` (created if
+    needed) and return their paths. The proposal file carries the candidate IR + provenance; the
+    outcome file branches on the outcome type — a ``ValidatedProposal`` writes its percentiles, a
+    ``Rejection`` writes its reason (and NO percentiles, mirroring the type distinction)."""
+    directory = Path(outbox_dir)
+    directory.mkdir(parents=True, exist_ok=True)
+
+    proposal_path = directory / f"{run_id}-proposal.json"
+    proposal_path.write_text(
+        _dump(
+            {
+                "run_id": run_id,
+                "proposal": outcome.proposal.model_dump(),
+                "provenance": provenance.model_dump(),
+            }
+        ),
+        encoding="utf-8",
+    )
+
+    if isinstance(outcome, ValidatedProposal):
+        outcome_payload: dict[str, Any] = {
+            "run_id": run_id,
+            "outcome_type": "validated",
+            "p10": outcome.p10,
+            "p50": outcome.p50,
+            "p90": outcome.p90,
+            "nominal_feasible": outcome.nominal_feasible,
+            "checker_verdict": checker_verdict,
+            "verdict_id": verdict_id,
+        }
+    else:
+        outcome_payload = {
+            "run_id": run_id,
+            "outcome_type": "rejected",
+            "reason": outcome.reason,
+            "checker_verdict": checker_verdict,
+            "verdict_id": verdict_id,
+        }
+    outcome_path = directory / f"{run_id}-outcome.json"
+    outcome_path.write_text(_dump(outcome_payload), encoding="utf-8")
+
+    return proposal_path, outcome_path