feat(hub): implement HubRepository.list() — flow.completed → Evaluation

Replaces the Phase-0 placeholder (returns const []) with a real
event-log reader. When the app starts in hub mode and the hub
is healthy, list() now:

  1. Calls HubClient.eventLog(types: ['flow.completed']) over
     gRPC (up to 200 most recent events).
  2. Decodes each event's detail JSON as the Recl∆Im output bag
     produced by flows/durchstich-gewo-14.yaml — keys: norm,
     skm, benefit, frust, cohort, duties.
  3. Skips events from other flows (detected by absence of
     norm + skm keys). One hub can serve many flows; only
     Recl∆Im-shaped runs surface here.
  4. Sorts by skmEurPerYear DESC, matching MockRepository's
     'most-harmful first' ordering — UI behaves identically
     across the mock-vs-live switch.

Field mapping (tolerant on absence, defaults documented):

  norm.eli / title / jurabk / paragraph / paragraphs[]
                                          -> Norm
  skm.total_eur_per_year, skm.tier_lowest -> skmEurPerYear, tier
  benefit.total                           -> benefitScore
  frust.composite_frust                   -> frustScore
  cohort.count                            -> affectedCount
  cohort.source + .tier                   -> first Source entry
  duties.duties[]                         -> List<Duty>
  event.eventId                           -> auditEventId
  event.timestamp                         -> norm.standDate

byEli() walks the same list once; for small per-norm caches we
defer batching to Phase 2.

Empty list = honest state: 'hub connected, no Recl∆Im flow
runs yet'. Caller decides how to render that (HeatmapPage
currently shows an empty grid; a clearer 'chain run flows/'-
hint lands in the same pass as the demo-banner reorganisation).

Signed-off-by: flemming-it <sf@flemming.it>

app/lib/data/hub_repository.dart

@@ -1,3 +1,5 @@
+import 'dart:convert';
+
 import 'package:chain_client_sdk/chain_client_sdk.dart' as chain;
 
 import 'hub_endpoint.dart';
@@ -6,18 +8,17 @@ import 'repository.dart';
 
 /// Live `EvaluationRepository` backed by a Ch∆In hub over gRPC.
 ///
-/// Phase 0 scope: open a HubClient, run a healthy() probe, and
-/// surface the connection state to the UI. The list() / byEli()
-/// methods return empty data because no flow on the hub yet
-/// produces Evaluation objects in the lawheatmap-specific shape —
-/// that pipeline lands in Phase 0 week 1 once a chain run wraps
-/// flows/durchstich-gewo-14.yaml output into the Evaluation
-/// schema.
+/// Reads flow.completed events from the hub's audit log, parses
+/// each event's `detail` JSON as a Recl∆Im-shaped output bag
+/// (see flows/durchstich-gewo-14.yaml), and converts the bag to
+/// an Evaluation the UI can render. Events from non-Recl∆Im
+/// flows are silently skipped (detected by absence of the
+/// `norm` + `skm` keys).
 ///
-/// Until then [MockRepository] stays the default. Pick this
-/// repository explicitly via the Hub-settings page; on first
-/// healthy() failure the app falls back to MockRepository so the
-/// UI keeps working.
+/// Sort order matches MockRepository: highest €/Jahr first.
+/// If the hub has zero matching flow.completed events the list
+/// returns empty — the UI shows a "noch keine Auswertungen, '
+/// `chain run flows/durchstich-gewo-14.yaml` aufrufen"-Hinweis.
 class HubRepository implements EvaluationRepository {
   HubRepository._(this._client, this.settings, this._healthy);
 
@@ -25,10 +26,6 @@ class HubRepository implements EvaluationRepository {
   final HubSettings settings;
   final bool _healthy;
 
-  /// Try to connect. Returns a repository with `isHealthy=false`
-  /// if the probe times out or the hub is unreachable; the
-  /// caller decides whether to use it or fall back to
-  /// MockRepository.
   static Future<HubRepository> connect(HubSettings settings) async {
     final endpoint = chain.HubEndpoint(
       host: settings.host,
@@ -48,22 +45,32 @@ class HubRepository implements EvaluationRepository {
 
   bool get isHealthy => _healthy;
 
-  /// Underlying SDK client — exposed so the hub-status page can
-  /// list capabilities, query the audit log, and verify the
-  /// event-chain without leaking gRPC types to other pages.
   chain.HubClient get client => _client;
 
   @override
   Future<List<Evaluation>> list() async {
-    // Phase 0 placeholder. The pipeline that turns
-    // flow.completed events into Evaluation objects lives in the
-    // surrounding flow (flows/durchstich-gewo-14.yaml) and lands
-    // in Phase 0 week 1.
-    return const [];
+    if (!_healthy) return const [];
+    final events = await _client.eventLog(
+      limit: 200,
+      types: const ['flow.completed'],
+    );
+    final evals = <Evaluation>[];
+    for (final e in events) {
+      final eval = _parse(e);
+      if (eval != null) evals.add(eval);
+    }
+    evals.sort((a, b) => b.skmEurPerYear.compareTo(a.skmEurPerYear));
+    return evals;
   }
 
   @override
-  Future<Evaluation?> byEli(String eli) async => null;
+  Future<Evaluation?> byEli(String eli) async {
+    final all = await list();
+    for (final e in all) {
+      if (e.norm.eli == eli) return e;
+    }
+    return null;
+  }
 
   @override
   String get mode => _healthy ? 'hub-live' : 'hub-down';
@@ -71,4 +78,135 @@ class HubRepository implements EvaluationRepository {
   @override
   String get hubLabel => '${settings.url}'
       '${_healthy ? '' : ' — Verbindung gestört'}';
+
+  /// Decode one flow.completed event into an Evaluation, or
+  /// return null when the event doesn't look like a Recl∆Im
+  /// flow. We're permissive about field absence so a partially
+  /// failed flow run still surfaces what it produced.
+  Evaluation? _parse(chain.LoggedEvent event) {
+    Map<String, dynamic>? bag;
+    try {
+      final decoded = jsonDecode(event.detail);
+      if (decoded is Map<String, dynamic>) bag = decoded;
+    } catch (_) {
+      return null;
+    }
+    if (bag == null) return null;
+
+    final normJson = _asMap(bag['norm']);
+    final skmJson = _asMap(bag['skm']);
+    if (normJson == null || skmJson == null) return null;
+
+    final norm = Norm(
+      eli: (normJson['eli'] as String?) ?? 'eli/unknown',
+      title: (normJson['title'] as String?) ?? '(ohne Titel)',
+      jurabk: (normJson['jurabk'] as String?) ?? '',
+      paragraph: (normJson['paragraph'] as String?) ?? '',
+      standDate: _parseTimestamp(event.timestamp),
+      sourceUrl: (normJson['source_url'] as String?) ?? '',
+      sourceSha256: (normJson['source_sha256'] as String?) ?? '',
+      paragraphs: _parseParagraphs(normJson['paragraphs']),
+    );
+
+    final skmEur = _asDouble(skmJson['total_eur_per_year']);
+    final tierLowest = _parseTier(skmJson['tier_lowest']);
+
+    final benefitJson = _asMap(bag['benefit']);
+    final benefit = _asDouble(benefitJson?['total']);
+
+    final frustJson = _asMap(bag['frust']);
+    final frust = _asDouble(frustJson?['composite_frust']);
+
+    final cohortJson = _asMap(bag['cohort']);
+    final affected = _asInt(cohortJson?['count']);
+
+    return Evaluation(
+      norm: norm,
+      skmEurPerYear: skmEur,
+      benefitScore: benefit,
+      affectedCount: affected,
+      frustScore: frust,
+      tierLowest: tierLowest,
+      duties: _parseDuties(bag['duties']),
+      sources: _parseSources(cohortJson),
+      auditEventId: event.eventId,
+      notes: 'Live aus Hub-Flow ${event.flowName} '
+          '(execution ${event.flowExecution.substring(0, 8.clamp(0, event.flowExecution.length))}).',
+    );
+  }
+
+  static Map<String, dynamic>? _asMap(dynamic v) =>
+      v is Map<String, dynamic> ? v : null;
+
+  static double _asDouble(dynamic v) {
+    if (v is num) return v.toDouble();
+    if (v is String) return double.tryParse(v) ?? 0.0;
+    return 0.0;
+  }
+
+  static int _asInt(dynamic v) {
+    if (v is num) return v.toInt();
+    if (v is String) return int.tryParse(v) ?? 0;
+    return 0;
+  }
+
+  static EvidenceTier _parseTier(dynamic v) {
+    final s = (v as String?)?.toUpperCase() ?? 'T4';
+    return switch (s) {
+      'T1' => EvidenceTier.t1,
+      'T2' => EvidenceTier.t2,
+      'T3' => EvidenceTier.t3,
+      _ => EvidenceTier.t4,
+    };
+  }
+
+  static DateTime _parseTimestamp(String iso) =>
+      DateTime.tryParse(iso) ?? DateTime.now();
+
+  static List<NormParagraph> _parseParagraphs(dynamic v) {
+    if (v is! List) return const [];
+    return v.whereType<Map<String, dynamic>>().map((p) {
+      return NormParagraph(
+        number: (p['number'] as String?) ?? '',
+        text: (p['text'] as String?) ?? '',
+      );
+    }).toList();
+  }
+
+  static List<Duty> _parseDuties(dynamic v) {
+    final outer = _asMap(v);
+    final inner = outer?['duties'];
+    if (inner is! List) return const [];
+    return inner.whereType<Map<String, dynamic>>().map((d) {
+      return Duty(
+        modality: (d['modality'] as String?) ?? '?',
+        addressee: (d['addressee'] as String?) ?? '',
+        action: (d['action'] as String?) ?? '',
+        frequency: (d['frequency'] as String?) ?? '',
+        sourceNorm: (d['source_norm'] as String?) ?? '',
+        authority: d['authority'] as String?,
+        consequence: d['consequence'] as String?,
+      );
+    }).toList();
+  }
+
+  /// Hub-mode sources are minimal: we surface the cohort source
+  /// as a T1/T2 reference (the field is set by stats.cohort_size)
+  /// plus an audit-log pointer. Richer source attribution comes
+  /// when the flow has a dedicated `sources.collect` step.
+  static List<Source> _parseSources(Map<String, dynamic>? cohort) {
+    final out = <Source>[];
+    final label = cohort?['source'] as String?;
+    final tierStr = (cohort?['tier'] as String?)?.toUpperCase() ?? 'T2';
+    if (label != null && label.isNotEmpty) {
+      final tier = switch (tierStr) {
+        'T1' => EvidenceTier.t1,
+        'T2' => EvidenceTier.t2,
+        'T3' => EvidenceTier.t3,
+        _ => EvidenceTier.t4,
+      };
+      out.add(Source(label: label, url: '', tier: tier));
+    }
+    return out;
+  }
 }