fix: enforce assistant data quality disclosures

CHANGELOG.md

@@ -27,6 +27,9 @@
 - Tightened generated answers to descriptive source evidence: estimates must
   remain labelled, unsupported causal/forecast claims are forbidden and plain
   text is requested for the existing chat renderer.
+- Added deterministic estimate disclosure for population answers and instructed
+  the local model to copy governed values literally instead of inventing
+  averages, rates or derived trends.
 
 ## Sprint 201 Semantic area-selection metrics (2026-07-15)
 

backend/app/services/geo_assistant_service.py

@@ -37,12 +37,48 @@ class GeoAssistantService:
         "gedaald",
         "gestegen",
     )
+    ESTIMATE_TOPIC_TERMS = {
+        "population": ("bevolk", "inwoner"),
+    }
+    ESTIMATE_TOPIC_LABELS = {
+        "population": "bevolkingswaarden",
+    }
 
     @classmethod
     def history_requested(cls, question: str) -> bool:
         normalized = question.casefold()
         return any(keyword in normalized for keyword in cls.HISTORY_KEYWORDS)
 
+    @classmethod
+    def ensure_estimate_disclosure(
+        cls,
+        answer: str,
+        metrics: list[AssistantContextMetric],
+    ) -> str:
+        normalized = answer.casefold()
+        if "schat" in normalized:
+            return answer
+        disclosed_themes = {
+            metric.theme
+            for metric in metrics
+            if metric.is_estimate
+            and any(
+                term in normalized
+                for term in cls.ESTIMATE_TOPIC_TERMS.get(metric.theme, (metric.label.casefold(),))
+            )
+        }
+        if not disclosed_themes:
+            return answer
+        labels = ", ".join(
+            cls.ESTIMATE_TOPIC_LABELS.get(theme, theme)
+            for theme in sorted(disclosed_themes)
+        )
+        return (
+            f"Datakwaliteit: {labels} in dit antwoord zijn schattingen volgens de bronmetadata, "
+            "geen exacte tellingen.\n\n"
+            f"{answer}"
+        )
+
     def __init__(self, settings: Settings | None = None):
         self.settings = settings or get_settings()
 
@@ -262,6 +298,9 @@ class GeoAssistantService:
                     )
                     context_metrics.append(item)
                     serialized_metrics.append(item.model_dump(mode="json"))
+                    serialized_metrics[-1]["measurement_quality"] = (
+                        "schatting" if item.is_estimate else "exact_binnen_bronrepresentatie"
+                    )
                 source_dataset_ids.append(dataset.id)
                 current_context.append(
                     {
@@ -307,6 +346,9 @@ class GeoAssistantService:
                             "value": summary["metric_value"],
                             "unit": summary["metric_unit"],
                             "is_estimate": summary["is_estimate"],
+                            "measurement_quality": (
+                                "schatting" if summary["is_estimate"] else "exact_binnen_bronrepresentatie"
+                            ),
                         }
                     )
                     if dataset.id not in source_dataset_ids:
@@ -356,6 +398,7 @@ class GeoAssistantService:
             "Als is_estimate true is, noem de waarde verplicht een schatting en nooit exact. "
             "Objectaantallen zijn ondersteunend; geef betekenisvolle oppervlakte-, lengte- of bevolkingsmetriek voorrang. "
             "Beschrijf alleen waargenomen verschillen; verzin geen oorzaak, voorspelling, verzadiging of andere verklaring. "
+            "Neem waarden en jaren letterlijk over en bereken zelf geen gemiddelde, tempo, oorzaak of afgeleide trend. "
             "Gebruik platte tekst met korte alinea's en opsommingen, zonder Markdown-symbolen. "
             "Bereken of suggereer nooit watervolume zonder gekoppelde diepte of bathymetrie. "
             "Als de gevraagde informatie niet in de context staat, zeg precies welke bron of meting ontbreekt. "
@@ -393,6 +436,7 @@ class GeoAssistantService:
         answer = str(message.get("content") or "").strip()
         if not answer:
             raise AppError(code="OLLAMA_EMPTY_RESPONSE", message="Ollama gaf geen antwoord terug.", status_code=502)
+        answer = self.ensure_estimate_disclosure(answer, metrics)
         return AssistantQueryResponse(
             answer=answer,
             model=model,

backend/tests/test_sprint202_temporal_metrics_and_ollama.py

@@ -98,6 +98,51 @@ def test_geo_assistant_recognizes_dutch_historical_questions(question: str) -> N
     assert GeoAssistantService.history_requested(question) is True
 
 
+def test_geo_assistant_discloses_estimated_population_values() -> None:
+    metrics = [
+        AssistantContextMetric(
+            theme="population",
+            label="Geschatte bevolking",
+            value=74_254,
+            unit="personen",
+            source="Statbel",
+            dataset_id=uuid4(),
+            is_estimate=True,
+        )
+    ]
+
+    answer = GeoAssistantService.ensure_estimate_disclosure(
+        "De bevolking bedraagt 74.254 personen.",
+        metrics,
+    )
+
+    assert answer.startswith(
+        "Datakwaliteit: bevolkingswaarden in dit antwoord zijn schattingen volgens de bronmetadata, "
+        "geen exacte tellingen."
+    )
+
+
+def test_geo_assistant_does_not_add_irrelevant_estimate_disclosure() -> None:
+    metrics = [
+        AssistantContextMetric(
+            theme="population",
+            label="Geschatte bevolking",
+            value=74_254,
+            unit="personen",
+            source="Statbel",
+            dataset_id=uuid4(),
+            is_estimate=True,
+        )
+    ]
+
+    answer = GeoAssistantService.ensure_estimate_disclosure(
+        "De bosoppervlakte bedraagt 3.626,56 hectare.",
+        metrics,
+    )
+
+    assert answer == "De bosoppervlakte bedraagt 3.626,56 hectare."
+
+
 def test_geo_assistant_sends_grounded_context_without_thinking_trace(monkeypatch) -> None:
     service = GeoAssistantService(ollama_settings())
     project_id = uuid4()
@@ -161,6 +206,7 @@ def test_geo_assistant_sends_grounded_context_without_thinking_trace(monkeypatch
     assert "scope.label is het exact geanalyseerde gebied" in captured["payload"]["messages"][0]["content"]
     assert "noem de waarde verplicht een schatting" in captured["payload"]["messages"][0]["content"]
     assert "verzin geen oorzaak, voorspelling, verzadiging" in captured["payload"]["messages"][0]["content"]
+    assert "bereken zelf geen gemiddelde, tempo, oorzaak of afgeleide trend" in captured["payload"]["messages"][0]["content"]
     assert "zonder Markdown-symbolen" in captured["payload"]["messages"][0]["content"]
     assert "water_volume_available" in captured["payload"]["messages"][0]["content"]
 

docs/CODEX_EXECUTION_LOG.md

@@ -8417,6 +8417,11 @@ Validation evidence:
   was suggested. The system contract now mandates estimate wording, forbids
   causal/forecast claims not present in context, uses deterministic temperature
   zero and requests plain text. Full readiness remained green at 617 tests.
+- Assistant context now carries explicit measurement quality for current and
+  historical values. A deterministic response guard prepends the estimate
+  limitation whenever an answer discusses estimated population data, while the
+  model prompt forbids independent averages, rates and derived trends. Focused
+  tests and full readiness passed with 619 backend tests.
 
 Known limitations:
 - Water volume remains unavailable until a governed depth/bathymetry source is