Fix rate limit provenance cap

internal/mcp/server_info.go

@@ -77,9 +77,29 @@ func publicLimits(options Options) map[string]any {
 	}
 }
 
+const maxPublicRateLimits = 8
+
 func publicRateLimits(rateLimits []stratz.RateLimit) []any {
-	result := make([]any, 0, len(rateLimits))
+	type rateLimitKey struct {
+		window string
+		source string
+	}
+	ordered := make([]rateLimitKey, 0, min(len(rateLimits), maxPublicRateLimits))
+	latest := make(map[rateLimitKey]stratz.RateLimit, min(len(rateLimits), maxPublicRateLimits))
 	for _, rateLimit := range rateLimits {
+		key := rateLimitKey{window: rateLimit.Window, source: rateLimit.Source}
+		if _, ok := latest[key]; !ok {
+			if len(ordered) >= maxPublicRateLimits {
+				continue
+			}
+			ordered = append(ordered, key)
+		}
+		latest[key] = rateLimit
+	}
+
+	result := make([]any, 0, len(ordered))
+	for _, key := range ordered {
+		rateLimit := latest[key]
 		var resetAt any
 		if rateLimit.ResetAt != nil {
 			resetAt = rateLimit.ResetAt.UTC().Format(time.RFC3339)

internal/mcp/server_test.go

@@ -116,6 +116,35 @@ func testServer(t *testing.T, logger *slog.Logger) *Server {
 	return server
 }
 
+func TestPublicRateLimitsDedupeAndCap(t *testing.T) {
+	firstRemaining := int64(149)
+	latestRemaining := int64(145)
+	minuteLimit := int64(150)
+	rateLimits := []stratz.RateLimit{
+		{Window: "minute", Limit: &minuteLimit, Remaining: &firstRemaining, Source: "fixture-minute"},
+		{Window: "minute", Limit: &minuteLimit, Remaining: &latestRemaining, Source: "fixture-minute"},
+	}
+	for index := range 10 {
+		limit := int64(100 + index)
+		remaining := int64(90 + index)
+		rateLimits = append(rateLimits, stratz.RateLimit{
+			Window:    "unknown",
+			Limit:     &limit,
+			Remaining: &remaining,
+			Source:    fmt.Sprintf("extra-%d", index),
+		})
+	}
+
+	public := publicRateLimits(rateLimits)
+	if len(public) != maxPublicRateLimits {
+		t.Fatalf("rate limit count = %d, want %d", len(public), maxPublicRateLimits)
+	}
+	first := public[0].(map[string]any)
+	if first["window"] != "minute" || first["remaining"] != &latestRemaining {
+		t.Fatalf("first rate limit = %#v, want latest minute fixture", first)
+	}
+}
+
 func TestSDKConformance(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()