test(s54): value_report overlap-flag load-bearing seam

tests/test_value_report_loadbearing.py

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+"""Load-bearing seam for the S5.4 value report's overlap flagging (målbilde §7).
+
+DETACH POINTS THAT TURN THIS RED (documented, not stubbed — the assertions ARE the seam lock):
+  1. Drop the ``overlaps=ledger.overlaps()`` surfacing in ``build_value_report`` -> the marker
+     overlap key vanishes from BOTH the text and the JSON output -> the positive arm goes RED.
+  2. Bypass the ledger's dimension-free dedup (``_dedup_amount`` / ``_sum_key``) -> the same
+     candidate realized under two dimensions is double-counted -> ``portfolio_total_ore`` doubles to
+     ``2 * _MARKER_ORE`` -> the control arm goes RED.
+
+The MARKER amount + identity appear NOWHERE else in the repo (marker convention,
+``tests/test_run_cli_loadbearing.py:25``; absence grep-verified before choosing), so a rendered
+match is provably caused by THIS ledger flowing through the report, not by incidental repo text.
+
+Reuses the same-candidate-two-dimensions construction from
+``tests/test_ledger_loadbearing.py:52-66``, rendered through the report.
+"""
+
+from __future__ import annotations
+
+import json
+
+from portfolio_optimiser.ledger import LedgerEntry, SavingsLedger
+from portfolio_optimiser.value_report import (
+    build_value_report,
+    dump_report_json,
+    format_report_text,
+)
+
+_MARKER_ORE = 58917  # marker: appears nowhere else in the codebase
+_MARKER_ID = "c-marker-overlap-s54"  # marker: appears nowhere else in the codebase
+
+
+def _overlap_ledger() -> SavingsLedger:
+    """One candidate (``_MARKER_ID``) realized under TWO dimensions (energi + asfalt) in P1 — a
+    distinct FULL storage key each, so both are stored (the overlap is visible), while the
+    dimension-free dedup counts the ``_MARKER_ORE`` amount ONCE."""
+    led = SavingsLedger()
+    for dimension in ("energi", "asfalt"):
+        led.add_realized(
+            LedgerEntry(
+                project_id="P1",
+                dimension=dimension,
+                candidate_identity=_MARKER_ID,
+                amount_ore=_MARKER_ORE,
+                verdict_id="v-marker",
+                provenance="marker-prov",
+            )
+        )
+    return led
+
+
+def test_overlap_marker_is_flagged_in_both_renderings() -> None:
+    """POSITIVE: the marker overlap key ``(P1, _MARKER_ID)`` reaches BOTH the human table AND the
+    JSON ``overlaps`` list. RED if ``build_value_report`` stops surfacing ``ledger.overlaps()``."""
+    report = build_value_report(_overlap_ledger())
+
+    assert ("P1", _MARKER_ID) in report.overlaps
+    assert _MARKER_ID in format_report_text(report)  # flagged in the rendered table
+
+    payload = json.loads(dump_report_json(report))
+    assert ["P1", _MARKER_ID] in payload["overlaps"]  # flagged in the JSON (tuple -> list)
+
+
+def test_overlap_amount_counted_once_not_doubled() -> None:
+    """CONTROL: the cross-dimension overlap is counted ONCE in the portfolio total, never doubled.
+    RED if the ledger's dimension-free dedup is bypassed (the total would become ``2 * _MARKER_ORE``
+    = 117834). This is the exact double-count the ledger's dedup was built to prevent."""
+    report = build_value_report(_overlap_ledger())
+
+    assert report.portfolio_total_ore == _MARKER_ORE  # once, NOT 2 * _MARKER_ORE
+    assert report.per_project["P1"] == _MARKER_ORE