feat(site-finder): add «7. Концепция» section to light analysis report

Fold the generative concept generator (3 strategy variants: placement map +
ТЭП + finance) into the light analysis report (/site-finder/analysis/{cad}) as
a new section after «6. Прогноз», so Концепция lives in one place alongside the
report instead of a separate flow (epic #1953, #1965 Stage 1).

Frontend-only: reuses ConceptParamsForm / ConceptVariantsResult and the
/concepts mutation (useCreateConcept) as-is — no duplication, no backend change.
Inputs are seeded from the analysis the report already has (no re-entry of the
cadastre/polygon): polygon ← extractPolygon(geom_geojson); housing_class /
development_type ← financial_estimate inferred values; land_cost ←
egrn.cadastral_value_rub; falls back to comfort/mid_rise.

Runs on demand (heavy generative call — never auto on mount); result block
(Leaflet map) is lazy-mounted via dynamic({ ssr: false }) and the section is
collapsed by default. When financial_estimate is null (ЗОУИТ/СЗЗ/нет зоны) it
shows an honest banner but still allows a manual run, since /concepts is
independent of the financial_estimate gate. Graceful empty state when geometry
is missing/unsupported. Stage 2 (interactive 3D + /concepts/recompute) left as
a seam, not built.

frontend/src/app/site-finder/analysis/[cad]/AnalysisPageContent.tsx

@@ -13,6 +13,7 @@ import { Section3SettingsAndCompetitors } from "@/components/site-finder/analysi
 import { Section4Estimate } from "@/components/site-finder/analysis/Section4Estimate";
 import { Section5Atmosphere } from "@/components/site-finder/analysis/Section5Atmosphere";
 import { Section6Forecast } from "@/components/site-finder/analysis/Section6Forecast";
+import { Section7Concept } from "@/components/site-finder/analysis/Section7Concept";
 import { useParcelAnalyzeQuery } from "@/lib/site-finder-api";
 import type { ParcelAnalysis } from "@/types/site-finder";
 
@@ -218,6 +219,11 @@ export function AnalysisPageContent({ cad }: Props) {
           {/* 6. Прогноз и рекомендация — IMPLEMENTED in 958-B3 (§22 forecast) */}
           <Section6Forecast cad={cad} selectedHorizon={horizon} />
 
+          {/* 7. Концепция — генеративный дизайн застройки (#1965 Stage 1).
+              Seeded из анализа (geom + financial_estimate), считается по
+              запросу; result lazy-mounted (Leaflet). */}
+          <Section7Concept analysis={analysis} />
+
           {/* Chat — grounded parcel-chat over the §22 forecast (#958) */}
           <ChatPanel cadNum={cad} />
         </div>
@@ -364,6 +370,7 @@ const NAV_GROUPS: NavGroup[] = [
           { id: "section-6-6", label: "6.6 Будущее предложение и конкуренты" },
         ],
       },
+      { id: "section-7", label: "7. Концепция" },
     ],
   },
 ];

frontend/src/components/site-finder/analysis/Section7Concept.tsx

@@ -0,0 +1,327 @@
+"use client";
+
+/**
+ * Section7Concept — «7. Концепция» (epic #1953, #1965 Stage 1).
+ *
+ * Folds the generative concept generator (3 strategy variants: placement map +
+ * ТЭП + financial model) into the LIGHT analysis report as a new section AFTER
+ * «6. Прогноз». Frontend-only: it reuses the existing concept components
+ * (ConceptParamsForm / ConceptVariantsResult) and the /concepts mutation
+ * (useCreateConcept) AS-IS — no duplication, no backend change.
+ *
+ * Inputs are seeded from the analysis the report already has (no re-entry of the
+ * cadastre / polygon):
+ *   • parcel polygon  ← extractPolygon(analysis.geom_geojson)
+ *   • housing_class   ← financial_estimate.housing_class_inferred
+ *   • development_type← financial_estimate.development_type_inferred
+ *   • land_cost_rub   ← egrn.cadastral_value_rub
+ * Falls back to comfort / mid_rise when those are null.
+ *
+ * On-demand only: the generative call is heavy, so it runs from a button — never
+ * auto on mount. The result block (Leaflet map) is lazy-mounted via `dynamic(…,
+ * { ssr: false })`. The section defaults to collapsed (above-the-fold rule).
+ *
+ * СЗЗ / financial_estimate === null is NOT a dead end: /concepts only needs a
+ * polygon + the form inputs (it is independent of the financial_estimate
+ * regulatory gate), so we show an honest banner and STILL allow a manual run.
+ *
+ * Stage 2 (separate PR) wires an interactive 3D MassingScene + a /concepts/
+ * recompute endpoint for live economics — left as a clear seam here, not built.
+ */
+
+import dynamic from "next/dynamic";
+import { useMemo, useState } from "react";
+
+import { HeadlineBar } from "@/components/ui/HeadlineBar";
+import { Section } from "@/components/analytics/Section";
+import {
+  ConceptParamsForm,
+  DEFAULT_PARAMS,
+  type ConceptParams,
+} from "@/components/concept/ConceptParamsForm";
+import {
+  extractPolygon,
+  polygonAreaSqm,
+  useCreateConcept,
+  type DevelopmentType,
+  type HousingClass,
+} from "@/lib/concept-api";
+import type { ParcelAnalysis } from "@/types/site-finder";
+
+// ConceptVariantsResult hosts a Leaflet placement map — lazy-mount, no SSR, so
+// it never bloats the main report bundle (loaded only when results exist).
+const ConceptVariantsResult = dynamic(
+  () =>
+    import("@/components/concept/ConceptVariantsResult").then(
+      (m) => m.ConceptVariantsResult,
+    ),
+  {
+    ssr: false,
+    loading: () => (
+      <div
+        style={{
+          height: 200,
+          background: "var(--bg-card-alt)",
+          border: "1px solid var(--border-card)",
+          borderRadius: 12,
+          display: "flex",
+          alignItems: "center",
+          justifyContent: "center",
+          color: "var(--fg-tertiary)",
+          fontSize: 13,
+        }}
+      >
+        Загрузка результата…
+      </div>
+    ),
+  },
+);
+
+const SCROLL_MARGIN = 72;
+
+// ── Narrowing helpers (inferred values are typed `string` on the analysis) ────
+
+const HOUSING_CLASSES: readonly HousingClass[] = [
+  "econom",
+  "comfort",
+  "business",
+];
+const DEVELOPMENT_TYPES: readonly DevelopmentType[] = [
+  "spot",
+  "mid_rise",
+  "high_rise",
+];
+
+function asHousingClass(value: string | undefined): HousingClass | null {
+  return value != null && (HOUSING_CLASSES as readonly string[]).includes(value)
+    ? (value as HousingClass)
+    : null;
+}
+
+function asDevelopmentType(value: string | undefined): DevelopmentType | null {
+  return value != null &&
+    (DEVELOPMENT_TYPES as readonly string[]).includes(value)
+    ? (value as DevelopmentType)
+    : null;
+}
+
+const ha = (sqm: number) =>
+  (sqm / 10_000).toLocaleString("ru-RU", { maximumFractionDigits: 2 });
+
+// ── Props ─────────────────────────────────────────────────────────────────────
+
+interface Props {
+  /** The /analyze response the report already holds — no re-fetch / re-entry. */
+  analysis: ParcelAnalysis;
+}
+
+// ── Section7Concept ───────────────────────────────────────────────────────────
+
+export function Section7Concept({ analysis }: Props) {
+  // Parcel polygon from the analysis geometry (handles Polygon / MultiPolygon /
+  // null → null; MultiPolygon collapses to its first ring per extractPolygon).
+  const polygon = useMemo(
+    () => extractPolygon(analysis.geom_geojson),
+    [analysis.geom_geojson],
+  );
+
+  // Seed form defaults from the analysis: inferred class/type + cadastral value.
+  // financial_estimate is null under the regulatory gate (СЗЗ / ЗОУИТ / нет
+  // зоны) — fall back to the shared DEFAULT_PARAMS (comfort / mid_rise) so a
+  // manual run is still possible.
+  const fin = analysis.financial_estimate;
+  const seededParams = useMemo<ConceptParams>(() => {
+    return {
+      housing_class:
+        asHousingClass(fin?.housing_class_inferred) ??
+        DEFAULT_PARAMS.housing_class,
+      development_type:
+        asDevelopmentType(fin?.development_type_inferred) ??
+        DEFAULT_PARAMS.development_type,
+      target_floors: DEFAULT_PARAMS.target_floors,
+      land_cost_rub:
+        analysis.egrn?.cadastral_value_rub ?? DEFAULT_PARAMS.land_cost_rub,
+    };
+  }, [fin, analysis.egrn?.cadastral_value_rub]);
+
+  const [params, setParams] = useState<ConceptParams>(seededParams);
+  const concept = useCreateConcept();
+
+  const financeUnavailable = fin == null;
+
+  function handleGenerate() {
+    if (!polygon) return;
+    concept.mutate({
+      parcel_geojson: polygon,
+      housing_class: params.housing_class,
+      target_floors: params.target_floors,
+      development_type: params.development_type,
+      land_cost_rub: params.land_cost_rub,
+    });
+  }
+
+  const parcelAreaSqm = polygon ? polygonAreaSqm(polygon) : 0;
+
+  return (
+    <section id="section-7" style={{ scrollMarginTop: SCROLL_MARGIN }}>
+      <HeadlineBar
+        title="7. Концепция"
+        subtitle="Генеративный дизайн застройки: три стратегии размещения с расчётом ТЭП и финансовой модели. Считается по запросу из геометрии и параметров этого участка."
+      />
+
+      {/* Collapsed by default (above-the-fold rule) — form + button inside;
+          heavy result is lazy-mounted only after a run. */}
+      <details style={{ marginTop: 12 }}>
+        <summary
+          style={{
+            cursor: "pointer",
+            fontSize: 14,
+            fontWeight: 600,
+            color: "var(--fg-primary)",
+            padding: "8px 0",
+          }}
+        >
+          Рассчитать концепцию застройки для участка
+        </summary>
+
+        <div style={{ marginTop: 12 }}>
+          {/* Graceful empty state — geometry missing / unsupported. */}
+          {!polygon ? (
+            <Section title="Концепция застройки">
+              <p
+                style={{
+                  margin: 0,
+                  fontSize: 13,
+                  color: "var(--fg-secondary)",
+                }}
+              >
+                Геометрия участка недоступна — концепцию построить нельзя.
+                Геометрия загружается из НСПД; повторите анализ позже либо
+                воспользуйтесь страницей «Концепция застройки», где границы
+                можно задать вручную.
+              </p>
+            </Section>
+          ) : (
+            <>
+              {/* СЗЗ / нет финмодели по регламенту — честный баннер, но НЕ
+                  тупик: /concepts работает по полигону + параметрам формы
+                  независимо от регуляторного гейта financial_estimate. */}
+              {financeUnavailable && (
+                <div
+                  role="note"
+                  style={{
+                    marginBottom: 12,
+                    padding: "12px 16px",
+                    background: "var(--warn-soft)",
+                    border: "1px solid var(--warn)",
+                    borderRadius: 12,
+                    fontSize: 13,
+                    lineHeight: "20px",
+                    color: "var(--fg-primary)",
+                  }}
+                >
+                  Финмодель по регламенту недоступна — на участке ЗОУИТ / СЗЗ
+                  либо не определена территориальная зона. Концепцию можно
+                  рассчитать вручную: укажите класс, тип застройки и этажность
+                  ниже — движок построит варианты по геометрии участка и
+                  заданным параметрам.
+                </div>
+              )}
+
+              <div
+                style={{
+                  display: "grid",
+                  gridTemplateColumns: "minmax(0, 1fr) 320px",
+                  gap: 16,
+                  alignItems: "start",
+                }}
+              >
+                <Section
+                  title="Участок"
+                  subtitle="Границы взяты из геометрии анализа — повторно вводить кадастр не нужно."
+                >
+                  <div
+                    style={{
+                      fontSize: 13,
+                      color: "var(--fg-primary)",
+                    }}
+                  >
+                    Кадастровый номер {analysis.cad_num} · площадь ≈{" "}
+                    {ha(parcelAreaSqm)} га.
+                  </div>
+                  <p
+                    style={{
+                      margin: "8px 0 0",
+                      fontSize: 12,
+                      color: "var(--fg-tertiary)",
+                    }}
+                  >
+                    Параметры по умолчанию подставлены из анализа: класс и тип
+                    застройки — из оценки участка, стоимость — из кадастровой
+                    стоимости (если есть). Можно скорректировать.
+                  </p>
+                </Section>
+
+                <Section
+                  title="Параметры проекта"
+                  subtitle="Класс, тип застройки и этажность."
+                >
+                  <ConceptParamsForm
+                    params={params}
+                    onChange={setParams}
+                    onSubmit={handleGenerate}
+                    hasPolygon={polygon != null}
+                    isPending={concept.isPending}
+                  />
+                </Section>
+              </div>
+
+              {/* Results */}
+              {concept.isError && (
+                <div style={{ marginTop: 16 }}>
+                  <Section title="Варианты застройки">
+                    <p
+                      style={{
+                        margin: 0,
+                        fontSize: 13,
+                        color: "var(--danger)",
+                      }}
+                      role="alert"
+                    >
+                      Не удалось рассчитать концепции: {concept.error.message}
+                    </p>
+                  </Section>
+                </div>
+              )}
+
+              {concept.isPending && (
+                <div style={{ marginTop: 16 }}>
+                  <Section title="Варианты застройки">
+                    <p
+                      style={{
+                        margin: 0,
+                        fontSize: 13,
+                        color: "var(--fg-secondary)",
+                      }}
+                    >
+                      Движок рассчитывает варианты размещения…
+                    </p>
+                  </Section>
+                </div>
+              )}
+
+              {concept.isSuccess && (
+                <div style={{ marginTop: 24 }}>
+                  <ConceptVariantsResult
+                    parcel={polygon}
+                    variants={concept.data.variants}
+                  />
+                </div>
+              )}
+            </>
+          )}
+        </div>
+      </details>
+    </section>
+  );
+}