feat(agent): surface the AI500 index board in chat, tools, and sidebar

- provider/nofxos: GetAI500ListCached — 5min TTL cache with stale
  fallback on upstream failure; ResolveClient routes through the claw402
  gateway when a wallet key is configured (user's claw402 model key ->
  CLAW402_WALLET_KEY env -> direct nofxos)
- new GET /api/ai500 endpoint serving the score-sorted board
- new get_ai500_list agent tool + prompt rule: when the user wants coin
  picks or creates a strategy without naming coins, consult AI500's
  high-scoring entries by default
- web: AI500 sidebar panel (rank, score badge, gain since entry,
  5min auto-refresh); clicking an entry asks the agent to analyze it

agent/ai500.go

@@ -0,0 +1,122 @@
+package agent
+
+import (
+	"encoding/json"
+	"fmt"
+	"sort"
+	"strings"
+
+	"nofx/provider/nofxos"
+	"nofx/store"
+)
+
+const (
+	ai500DefaultLimit = 20
+	ai500MaxLimit     = 100
+)
+
+// fetchAI500ForTool is swappable in tests. It resolves a nofxos client
+// (routed through claw402 when a wallet key is available) and returns the
+// cached AI500 board.
+var fetchAI500ForTool = func(walletKey string) ([]nofxos.CoinData, error) {
+	return nofxos.GetAI500ListCached(nofxos.ResolveClient(walletKey))
+}
+
+// Claw402WalletKeyForStoreUser returns the wallet private key of the user's
+// enabled claw402 model, if any, so data requests can be routed through the
+// claw402 payment gateway on the user's own account.
+func Claw402WalletKeyForStoreUser(st *store.Store, storeUserID string) string {
+	if st == nil {
+		return ""
+	}
+	if strings.TrimSpace(storeUserID) == "" {
+		storeUserID = "default"
+	}
+	models, err := st.AIModel().List(storeUserID)
+	if err != nil {
+		return ""
+	}
+	for _, model := range models {
+		if model == nil || !model.Enabled {
+			continue
+		}
+		if strings.EqualFold(strings.TrimSpace(model.Provider), "claw402") && len(model.APIKey) > 0 {
+			return string(model.APIKey)
+		}
+	}
+	return ""
+}
+
+// AI500BoardEntry is the display shape for one AI500 constituent.
+type AI500BoardEntry struct {
+	Pair            string  `json:"pair"`
+	Score           float64 `json:"score"`
+	MaxScore        float64 `json:"max_score"`
+	IncreasePercent float64 `json:"increase_percent"`
+	StartPrice      float64 `json:"start_price"`
+	StartTime       int64   `json:"start_time"`
+}
+
+// AI500Board returns the AI500 constituents sorted by score (descending),
+// truncated to limit.
+func AI500Board(walletKey string, limit int) ([]AI500BoardEntry, error) {
+	if limit <= 0 {
+		limit = ai500DefaultLimit
+	}
+	if limit > ai500MaxLimit {
+		limit = ai500MaxLimit
+	}
+	coins, err := fetchAI500ForTool(walletKey)
+	if err != nil {
+		return nil, err
+	}
+	sorted := make([]nofxos.CoinData, len(coins))
+	copy(sorted, coins)
+	sort.SliceStable(sorted, func(i, j int) bool {
+		return sorted[i].Score > sorted[j].Score
+	})
+	if len(sorted) > limit {
+		sorted = sorted[:limit]
+	}
+	out := make([]AI500BoardEntry, 0, len(sorted))
+	for _, coin := range sorted {
+		out = append(out, AI500BoardEntry{
+			Pair:            coin.Pair,
+			Score:           coin.Score,
+			MaxScore:        coin.MaxScore,
+			IncreasePercent: coin.IncreasePercent,
+			StartPrice:      coin.StartPrice,
+			StartTime:       coin.StartTime,
+		})
+	}
+	return out, nil
+}
+
+// toolGetAI500List exposes the AI500 board to the chat agent.
+func (a *Agent) toolGetAI500List(storeUserID, argsJSON string) string {
+	var args struct {
+		Limit int `json:"limit"`
+	}
+	if strings.TrimSpace(argsJSON) != "" {
+		if err := json.Unmarshal([]byte(argsJSON), &args); err != nil {
+			return fmt.Sprintf(`{"error":"invalid arguments: %s"}`, err)
+		}
+	}
+
+	walletKey := Claw402WalletKeyForStoreUser(a.store, storeUserID)
+	entries, err := AI500Board(walletKey, args.Limit)
+	if err != nil {
+		return fmt.Sprintf(`{"error":"failed to fetch AI500 list: %s"}`, err)
+	}
+
+	payload, err := json.Marshal(map[string]any{
+		"status": "ok",
+		"count":  len(entries),
+		"coins":  entries,
+		"note":   "AI500 is an AI-scored crypto index; score is 0-100, increase_percent is the gain since the coin entered the index.",
+	})
+	if err != nil {
+		return fmt.Sprintf(`{"error":"failed to serialize AI500 list: %s"}`, err)
+	}
+	return string(payload)
+}