diff --git a/app/services/backtest_service.py b/app/services/backtest_service.py
index 14a3817..eaf7b2e 100644
--- a/app/services/backtest_service.py
+++ b/app/services/backtest_service.py
@@ -4436,11 +4436,38 @@ async def run_and_store(
 
 
 async def get_backtest_report(db: AsyncSession) -> dict | None:
-    """Return the last cached backtest report, or None if never run."""
+    """Return the last cached backtest report, or None if never run.
+
+    The recommendation is **re-derived from the cached report** rather than
+    served as stored. It is a pure function of the numbers already in the
+    report — the payload's own note says it is derived from them on every run —
+    so recomputing costs nothing and keeps one class of bug out:
+
+    A report cached by an older build carries that build's recommendation. After
+    a change to how the recommendation is sourced, the page would keep showing
+    the old one — quoting the legacy policy book, naming a rejected exit as
+    "recommended", and omitting ``basis_lookback``, which in turn let the
+    lookback selector default somewhere else. The result was the exact
+    tiles-disagree-with-recommendation contradiction this rebuild exists to
+    prevent, silently, until the next scheduled run happened to overwrite it.
+
+    Re-deriving means a corrected recommendation appears on the first page load
+    after deploy instead of after the next backtest.
+    """
     setting = await settings_store.get_setting(db, KEY_REPORT)
     if setting is None:
         return None
     try:
-        return json.loads(setting.value)
+        report = json.loads(setting.value)
     except (TypeError, ValueError):
         return None
+    if not isinstance(report, dict):
+        return None
+    try:
+        report["recommendation"] = _build_recommendation(report)
+    except Exception:
+        # Fail closed: drop it rather than fall back to the stored one, which is
+        # precisely the stale derivation this rebuild is here to replace.
+        logger.exception("Could not rebuild the backtest recommendation; omitting it")
+        report.pop("recommendation", None)
+    return report
diff --git a/tests/unit/test_backtest_service.py b/tests/unit/test_backtest_service.py
index 3a182df..b16303a 100644
--- a/tests/unit/test_backtest_service.py
+++ b/tests/unit/test_backtest_service.py
@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import json
 import math
 from datetime import date, timedelta
 from types import SimpleNamespace
@@ -1862,3 +1863,58 @@ def test_build_recommendation_states_no_baseline_without_a_production_row():
     assert "benchmark" not in topics
     assert "exit" not in topics
 
+
+async def test_cached_report_recommendation_is_rebuilt_on_read(session):
+    """A report cached by an older build carries that build's recommendation.
+
+    Served verbatim, the page would show the legacy wording and no
+    basis_lookback — which let the lookback selector default elsewhere, putting
+    3y tiles beside an all-history recommendation with no warning. This is the
+    shape of the report sitting in production right now.
+    """
+    from app.services.admin_service import update_setting
+
+    stale = {
+        "generated_at": "2026-08-12T05:00:00+00:00",
+        "tickers": 512, "candidates": 100, "qualified": 10,
+        "params": {"horizon_days": 30},
+        "overall_qualified": {"net_avg_r": 0.13, "net_avg_r_ex_top5": 0.20},
+        "portfolio_sim": {"policies": [
+            {"policy": "hold", "cagr_pct": 31.9, "total_return_pct": 175.0,
+             "spy_return_pct": 101.9, "max_drawdown_pct": 23.7},
+        ]},
+        "portfolio_monitor": {
+            "production_strategy": "prod",
+            "runs": [{
+                "strategy": "prod", "lookback": "all", "lookback_label": "All history",
+                "cagr_pct": 40.0, "sharpe": 1.72, "max_drawdown_pct": 17.7,
+                "total_return_pct": 297.8, "spy_return_pct": 101.9,
+            }],
+        },
+        # What the old build stored: sourced from the policy book, and naming an
+        # exit the production book replaced.
+        "recommendation": {
+            "headline": "Trade the qualified list long-only; hold 30 trading days.",
+            "items": [
+                {"topic": "benchmark", "text": "Book vs SPY: beats buy-and-hold by "
+                                               "+73.1 points (+175.0% vs +101.9%)."},
+                {"topic": "robustness", "text": "Robustness: expectancy survives removing "
+                                                "the top 5% of winners (+0.20R net/trade "
+                                                "under the recommended 30d hold)."},
+            ],
+            "note": "stale",
+        },
+    }
+    await update_setting(session, bt.KEY_REPORT, json.dumps(stale))
+
+    report = await bt.get_backtest_report(session)
+    assert report is not None
+    rec = report["recommendation"]
+
+    # Rebuilt: the basis is published, so the page cannot default elsewhere.
+    assert rec["basis_lookback"] == "all"
+    texts = " | ".join(i["text"] for i in rec["items"])
+    # ...and it quotes the production book, not the policy sim it used to.
+    assert "+297.8%" in texts and "175.0" not in texts
+    assert "recommended 30d hold" not in texts
+    assert "Production baseline" in (rec["headline"] or "")