feat(snapshots): evolution API, tactic breakdown and dashboard trend chart [FASE-5.2]

frontend/src/api/snapshots.ts

@@ -12,10 +12,28 @@ export interface SnapshotSummary {
   not_covered_count: number;
   in_progress_count: number;
   not_evaluated_count: number;
+  coverage_percentage?: number;
+  by_tactic?: Record<string, unknown>;
+  by_status?: Record<string, number>;
+  stale_count?: number;
+  never_tested_count?: number;
   created_by: string | null;
   created_at: string | null;
 }
 
+export interface CoverageEvolutionPoint {
+  date: string | null;
+  name: string | null;
+  org_score: number;
+  coverage_pct: number;
+  by_tactic: Record<string, unknown>;
+  by_status: Record<string, number>;
+  stale_count: number;
+  never_tested_count: number;
+  validated_count: number;
+  total_techniques: number;
+}
+
 export interface TechniqueState {
   mitre_id: string;
   technique_id: string;
@@ -76,6 +94,17 @@ export async function getSnapshot(snapshotId: string): Promise<SnapshotDetail> {
   return data;
 }
 
+/** Coverage trend points for dashboard charts. */
+export async function getCoverageEvolution(
+  months = 12,
+): Promise<CoverageEvolutionPoint[]> {
+  const { data } = await client.get<CoverageEvolutionPoint[]>(
+    "/snapshots/evolution",
+    { params: { months } },
+  );
+  return data;
+}
+
 /** Compare two snapshots. */
 export async function compareSnapshots(
   aId: string,

frontend/src/pages/DashboardPage.tsx

@@ -16,6 +16,16 @@ import {
   TrendingUp,
   ArrowRight,
 } from "lucide-react";
+import {
+  LineChart,
+  Line,
+  XAxis,
+  YAxis,
+  CartesianGrid,
+  Tooltip,
+  ResponsiveContainer,
+  Legend,
+} from "recharts";
 import {
   getCoverageSummary,
   getCoverageByTactic,
@@ -28,6 +38,7 @@ import {
   type ValidationRateItem,
   type RecentTestItem,
 } from "../api/metrics";
+import { getCoverageEvolution } from "../api/snapshots";
 import CoverageSummaryCard from "../components/CoverageSummaryCard";
 import TacticCoverageChart from "../components/TacticCoverageChart";
 import type { TestState } from "../types/models";
@@ -97,6 +108,11 @@ export default function DashboardPage() {
     queryFn: getRecentTests,
   });
 
+  const { data: coverageEvolution, isLoading: evolutionLoading } = useQuery({
+    queryKey: ["snapshots", "evolution", 6],
+    queryFn: () => getCoverageEvolution(6),
+  });
+
   if (summaryLoading || tacticsLoading) {
     return (
       <div className="flex h-64 items-center justify-center">
@@ -191,6 +207,67 @@ export default function DashboardPage() {
         </div>
       )}
 
+      {/* Coverage evolution (snapshots) */}
+      <div className="rounded-xl border border-gray-800 bg-gray-900 p-6">
+        <h2 className="mb-4 text-lg font-semibold text-white flex items-center gap-2">
+          <TrendingUp className="h-5 w-5 text-cyan-400" />
+          Coverage Evolution (6 months)
+        </h2>
+        {evolutionLoading ? (
+          <div className="flex h-48 items-center justify-center">
+            <Loader2 className="h-6 w-6 animate-spin text-cyan-400" />
+          </div>
+        ) : coverageEvolution && coverageEvolution.length > 0 ? (
+          <ResponsiveContainer width="100%" height={240}>
+            <LineChart data={coverageEvolution}>
+              <CartesianGrid strokeDasharray="3 3" stroke="#1f2937" />
+              <XAxis
+                dataKey="date"
+                tick={{ fill: "#6b7280", fontSize: 10 }}
+                tickFormatter={(val) => {
+                  const d = new Date(val);
+                  return `${d.getMonth() + 1}/${d.getDate()}`;
+                }}
+              />
+              <YAxis
+                domain={[0, 100]}
+                tick={{ fill: "#6b7280", fontSize: 10 }}
+              />
+              <Tooltip
+                contentStyle={{
+                  backgroundColor: "#111827",
+                  border: "1px solid #374151",
+                  borderRadius: "8px",
+                  fontSize: "12px",
+                }}
+                labelStyle={{ color: "#9ca3af" }}
+              />
+              <Legend />
+              <Line
+                type="monotone"
+                dataKey="org_score"
+                stroke="#06b6d4"
+                strokeWidth={2}
+                dot={{ r: 3 }}
+                name="Org score"
+              />
+              <Line
+                type="monotone"
+                dataKey="coverage_pct"
+                stroke="#22c55e"
+                strokeWidth={2}
+                dot={{ r: 3 }}
+                name="Coverage %"
+              />
+            </LineChart>
+          </ResponsiveContainer>
+        ) : (
+          <p className="text-sm text-gray-500 py-8 text-center">
+            No snapshots yet. Weekly snapshots populate this chart automatically.
+          </p>
+        )}
+      </div>
+
       {/* ── V2 Section: Test Pipeline ────────────────────────────────── */}
       <div className="rounded-xl border border-gray-800 bg-gray-900 p-6">
         <div className="mb-4 flex items-center justify-between">