ix ckpool.conf render dropping the TLS bind port; Let deployments declare what each stratum bind is

README.md

@@ -59,9 +59,11 @@ The Go API (`kamado-api`) bridges CKPool's Unix socket protocol, bitcoind's JSON
 
 ### Stratum TLS
 
-Optional encrypted stratum via stunnel. CKPool binds two stratum sockets — a public plaintext port and a loopback-only internal port. Stunnel terminates TLS on the external port and forwards decrypted traffic to the internal bind. CKPool tags connections by `serverurl` index (`server === 1` means TLS), which the dashboard reads to display a lock icon next to encrypted miners — no source-IP heuristics needed.
+Optional encrypted stratum via stunnel. CKPool binds a public plaintext socket plus one loopback-only socket per TLS certificate; stunnel terminates TLS on the external port and forwards decrypted traffic to the matching internal bind. CKPool tags each connection with its `serverurl` index, and the deployment declares what those indices mean via the `STRATUM_SERVERS` env — so the dashboard shows a lock icon next to encrypted miners and names the certificate in use on hover, with no source-IP heuristics.
 
-The TLS certificate is auto-generated on first start with broad SAN coverage (`.local`, `.embassy`, `.onion`, `.lan`, `.home.arpa`, `.internal`) so miner firmware that validates the SAN against the connection hostname (e.g. AxeOS with mbedtls) works without manual cert pinning. A version marker triggers automatic regeneration when the cert format changes.
+Under StartOS this drives two certificates on one port, chosen per connection by SNI: a CA-issued (Let's Encrypt) certificate for miners connecting over a clearnet domain, and the self-signed one for miners on the LAN, which send no SNI and fall through to it.
+
+The self-signed certificate is auto-generated on first start with broad SAN coverage (`.local`, `.embassy`, `.onion`, `.lan`, `.home.arpa`, `.internal`) so miner firmware that validates the SAN against the connection hostname (e.g. AxeOS with mbedtls) works without manual cert pinning. A version marker triggers automatic regeneration when the cert format changes.
 
 ### Dashboard
 
@@ -161,6 +163,7 @@ The dashboard is at `http://localhost:8080`. Point a miner at `stratum+tcp://loc
 | `BITCOIN_ZMQ_BLOCK` | (disabled) | no | ZMQ hashblock endpoint (e.g. `tcp://127.0.0.1:28332`) |
 | `BITCOIN_RPC_TIMEOUT` | `10s` | no | RPC call timeout |
 | `MEMPOOL_BASE_URL` | (mempool.space) | no | Custom mempool explorer URL |
+| `STRATUM_SERVERS` | (undeclared) | no | JSON array describing ckpool's `serverurl[]` binds, e.g. `[{"kind":"plain","label":"Plaintext"},{"kind":"tls-local","label":"TLS — self-signed"}]`. Entry N labels clients with `server == N` in the dashboard. Unset falls back to treating index 1 as TLS |
 
 ### UI Development
 

api/cmd/kamado-api/main.go

@@ -7,6 +7,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"log/slog"
@@ -65,6 +66,18 @@ func main() {
 	agg := state.New(ck, rpc, cfg.PollInterval, log)
 	agg.Store = blockStore
 	agg.MempoolBaseURL = cfg.MempoolBaseURL
+	// Purely descriptive (it drives the dashboard's connection badge), so a
+	// malformed value degrades to the UI's fallback rather than refusing to
+	// start a pool that is otherwise fine.
+	if cfg.StratumServersJSON != "" {
+		var servers []state.StratumServer
+		if err := json.Unmarshal([]byte(cfg.StratumServersJSON), &servers); err != nil {
+			log.Warn("ignoring malformed STRATUM_SERVERS", "err", err)
+		} else {
+			agg.StratumServers = servers
+			log.Info("stratum binds declared", "count", len(servers))
+		}
+	}
 	agg.LogFilePath = cfg.CKPoolLogFile
 	agg.KillCKPool = killCKPool(log)
 

api/internal/config/config.go

@@ -39,21 +39,29 @@ type Config struct {
 	// the UI uses the public mempool.space; non-empty means the user
 	// has pointed Kamado at their own instance via the StartOS config.
 	MempoolBaseURL string
+
+	// Optional JSON array describing ckpool's serverurl[] binds, so the
+	// dashboard can name the transport a miner connected over instead of
+	// guessing from the bind index. Rendered by whoever writes
+	// ckpool.conf; empty means "undeclared" and the UI falls back. Parsed
+	// in main (the concrete type lives with the snapshot it belongs to).
+	StratumServersJSON string
 }
 
 func FromEnv() (*Config, error) {
 	cfg := &Config{
-		ListenAddr:        getenv("LISTEN_ADDR", ":8080"),
+		ListenAddr:         getenv("LISTEN_ADDR", ":8080"),
-		CKPoolSockDir:     getenv("CKPOOL_SOCKDIR", "/run/ckpool"),
+		CKPoolSockDir:      getenv("CKPOOL_SOCKDIR", "/run/ckpool"),
-		BitcoinRPCURL:     os.Getenv("BITCOIN_RPC_URL"),
+		BitcoinRPCURL:      os.Getenv("BITCOIN_RPC_URL"),
-		BitcoinRPCUser:    os.Getenv("BITCOIN_RPC_USER"),
+		BitcoinRPCUser:     os.Getenv("BITCOIN_RPC_USER"),
 		BitcoinRPCPassword: os.Getenv("BITCOIN_RPC_PASSWORD"),
-		BitcoinRPCTimeout: getenvDuration("BITCOIN_RPC_TIMEOUT", 10*time.Second),
+		BitcoinRPCTimeout:  getenvDuration("BITCOIN_RPC_TIMEOUT", 10*time.Second),
-		BitcoinZMQBlock:   os.Getenv("BITCOIN_ZMQ_BLOCK"),
+		BitcoinZMQBlock:    os.Getenv("BITCOIN_ZMQ_BLOCK"),
-		CKPoolLogFile:     getenv("CKPOOL_LOGFILE", "/var/log/ckpool/ckpool.log"),
+		CKPoolLogFile:      getenv("CKPOOL_LOGFILE", "/var/log/ckpool/ckpool.log"),
-		DBPath:            getenv("DB_PATH", "/var/lib/kamado/kamado.db"),
+		DBPath:             getenv("DB_PATH", "/var/lib/kamado/kamado.db"),
-		PollInterval:      getenvDuration("POLL_INTERVAL", 5*time.Second),
+		PollInterval:       getenvDuration("POLL_INTERVAL", 5*time.Second),
-		MempoolBaseURL:    os.Getenv("MEMPOOL_BASE_URL"),
+		MempoolBaseURL:     os.Getenv("MEMPOOL_BASE_URL"),
+		StratumServersJSON: os.Getenv("STRATUM_SERVERS"),
 	}
 
 	if cfg.BitcoinRPCURL == "" {

api/internal/state/aggregator.go

@@ -25,6 +25,21 @@ type HashratePoint struct {
 	V float64 `json:"v"` // H/s
 }
 
+// StratumServer describes one entry in ckpool's serverurl[] array. ckpool
+// tags every client with the index of the bind it arrived on, but the index
+// alone doesn't say what that bind *is* — that depends on how the deployment
+// rendered ckpool.conf. Declaring the array lets the dashboard report the
+// actual transport (plaintext, TLS with which certificate) instead of
+// hardcoding a bind order.
+type StratumServer struct {
+	// Kind is the stable machine-readable tag the UI switches on:
+	// "plain", "tls-local" (package-managed self-signed certificate) or
+	// "tls-public" (CA-issued certificate for a public domain).
+	Kind string `json:"kind"`
+	// Label is the human-readable description shown on hover.
+	Label string `json:"label"`
+}
+
 // Snapshot is the merged view served to the UI. All fields are safe to
 // JSON-serialize directly.
 type Snapshot struct {
@@ -38,7 +53,7 @@ type Snapshot struct {
 	Clients []ckpool.StratumClient `json:"clients"`
 
 	// Derived/enriched fields
-	HashrateHs    float64 `json:"hashrate_hs_1m"`    // from PoolStats.DSPS1
+	HashrateHs    float64 `json:"hashrate_hs_1m"` // from PoolStats.DSPS1
 	HashrateHs5m  float64 `json:"hashrate_hs_5m"`
 	HashrateHs1h  float64 `json:"hashrate_hs_1h"`
 	HashrateHs24h float64 `json:"hashrate_hs_24h"`
@@ -68,8 +83,8 @@ type Snapshot struct {
 	NextDifficultyPercent float64 `json:"next_difficulty_percent"`
 
 	// Bitcoin Core fields
-	Chain                *bitcoind.BlockchainInfo `json:"chain"`
+	Chain             *bitcoind.BlockchainInfo `json:"chain"`
-	NetworkHashrateHs    float64                  `json:"network_hashrate_hs"`
+	NetworkHashrateHs float64                  `json:"network_hashrate_hs"`
 
 	// Recent found blocks (in-memory history; persisted in Phase 2b.5).
 	RecentBlocks []BlockRecord `json:"recent_blocks,omitempty"`
@@ -82,6 +97,13 @@ type Snapshot struct {
 	// the StartOS config "Block Explorer" -> "Custom URL".
 	MempoolBaseURL string `json:"mempool_base_url,omitempty"`
 
+	// Describes ckpool's serverurl[] array: entry N tells the UI what a
+	// client with `server == N` is actually connected over. Set via the
+	// STRATUM_SERVERS env by whoever renders ckpool.conf (the StartOS
+	// wrapper). Empty when undeclared, in which case the UI falls back to
+	// its historical "index 1 means TLS" assumption.
+	StratumServers []StratumServer `json:"stratum_servers,omitempty"`
+
 	// Counts of share-submit attempts ("Possible/Submitting block solve"
 	// log lines) and confirmed solves ("Solved and confirmed block").
 	// A growing gap means bitcoind is rejecting our submissions or
@@ -93,15 +115,15 @@ type Snapshot struct {
 	// LastZMQEventAge is the seconds-since the last bitcoind hashblock
 	// frame arrived; -1 means no event seen since startup. ZMQEnabled
 	// is whether the user configured an endpoint at all.
-	ZMQEnabled        bool    `json:"zmq_enabled"`
+	ZMQEnabled      bool    `json:"zmq_enabled"`
-	LastZMQEventAge   float64 `json:"last_zmq_event_age,omitempty"` // seconds; >=0
+	LastZMQEventAge float64 `json:"last_zmq_event_age,omitempty"` // seconds; >=0
-	HasLastZMQEvent   bool    `json:"has_last_zmq_event"`
+	HasLastZMQEvent bool    `json:"has_last_zmq_event"`
-	TipChangedAge     float64 `json:"tip_changed_age"`              // seconds since tip height last changed
+	TipChangedAge   float64 `json:"tip_changed_age"` // seconds since tip height last changed
 
 	// Bitcoin Core peer connections.
-	PeerCount    int `json:"peer_count"`
+	PeerCount int `json:"peer_count"`
-	PeersIn      int `json:"peers_in"`
+	PeersIn   int `json:"peers_in"`
-	PeersOut     int `json:"peers_out"`
+	PeersOut  int `json:"peers_out"`
 
 	// Share counters: raw counts (1 submission = 1 share regardless of diff).
 	// Session = since ckpool started; AllTime = persisted across restarts.
@@ -151,8 +173,8 @@ const (
 	kvLatencyLastMs   = "latency_last_ms"
 	kvStaleWorkHashes = "stale_work_hashes"
 
-	kvAckedBestDiff  = "acked_best_diff"
+	kvAckedBestDiff    = "acked_best_diff"
-	kvBestDiff       = "best_diff"
+	kvBestDiff         = "best_diff"
 	kvBestShareHash    = "best_share_hash"
 	kvBestShareNetDiff = "best_share_net_diff"
 
@@ -186,6 +208,10 @@ type Aggregator struct {
 	// MempoolBaseURL leaves the UI on its mempool.space defaults.
 	MempoolBaseURL string
 
+	// Declared meaning of each ckpool serverurl[] index; see StratumServer.
+	// Nil leaves the UI on its index-1-means-TLS fallback.
+	StratumServers []StratumServer
+
 	// LogFilePath is the ckpool log path, used for one-time backfill
 	// of the best share hash when upgrading from a version that didn't
 	// capture it. Set by main before calling Run.
@@ -220,10 +246,10 @@ type Aggregator struct {
 	// post-load observation of pool.Shares only establishes the
 	// baseline — the current ckpool counter was already accounted for
 	// before we crashed.
-	cumulativeShares       float64
+	cumulativeShares      float64
-	lastPoolShares         float64
+	lastPoolShares        float64
-	hasPoolSharesBaseline  bool
+	hasPoolSharesBaseline bool
-	lastCumulativeSave     time.Time
+	lastCumulativeSave    time.Time
 
 	// Next-block reward cache; refreshed on its own cadence so we don't
 	// hammer bitcoind with getblocktemplate on every poll tick.
@@ -245,8 +271,8 @@ type Aggregator struct {
 	// btcFailStreak counts consecutive refreshes where bitcoind was
 	// unreachable. After a threshold, if no block submission is pending,
 	// we kill the ckpool process so miners can failover to other pools.
-	btcFailStreak    int
+	btcFailStreak int
-	ckpoolKilled     bool // true after we sent SIGTERM, reset on bitcoind recovery
+	ckpoolKilled  bool // true after we sent SIGTERM, reset on bitcoind recovery
 
 	// readyOnce + ready closes the Ready() channel exactly once after
 	// the first refresh completes. main blocks briefly on this so the
@@ -401,7 +427,11 @@ func (a *Aggregator) refresh(ctx context.Context) {
 	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
 	defer cancel()
 
-	next := Snapshot{GeneratedAt: time.Now(), MempoolBaseURL: a.MempoolBaseURL}
+	next := Snapshot{
+		GeneratedAt:    time.Now(),
+		MempoolBaseURL: a.MempoolBaseURL,
+		StratumServers: a.StratumServers,
+	}
 
 	// --- ckpool: poolstats, users, workers, clients, uptime ---
 	if ps, err := a.CK.PoolStats(ctx); err == nil {
@@ -776,7 +806,6 @@ func diffBucket(d float64) int {
 // DiffBucketLabels are the human-readable labels for each difficulty bucket.
 var DiffBucketLabels = [6]string{"< 1M", "1M – 100M", "100M – 1G", "1G – 100G", "100G – 1T", "≥ 1T"}
 
-
 // IngestShareEvents reads individual share events from the log tailer
 // and maintains rejection-reason counts and difficulty-distribution
 // histograms. Session counters reset when ckpool restarts (detected by

ckpool/entrypoint.sh

@@ -49,6 +49,11 @@ LOGDIR="${LOGDIR:-/var/log/ckpool}"
 SOCKET_DIR="${SOCKET_DIR:-/run/ckpool}"
 SHARE_LOG="${SHARE_LOG:-1}"
 CKPOOL_LOGLEVEL="${CKPOOL_LOGLEVEL:-6}"
+# ckpool's second, loopback-only stratum bind. Nothing terminates TLS in the
+# dev compose stack, but the bind must still resolve: ckpool passes the port
+# straight to getaddrinfo() and a non-numeric service string is fatal
+# (connector.c logs "Failed to extract resolved url" and exit(1)s).
+TLS_INTERNAL_PORT="${TLS_INTERNAL_PORT:-3437}"
 
 mkdir -p "$LOGDIR" "$SOCKET_DIR"
 
@@ -68,6 +73,7 @@ sed \
     -e "s|\${BLOCKPOLL_MS}|${BLOCKPOLL_MS}|g" \
     -e "s|\${UPDATE_INTERVAL_S}|${UPDATE_INTERVAL_S}|g" \
     -e "s|\${STRATUM_PORT}|${STRATUM_PORT}|g" \
+    -e "s|\${TLS_INTERNAL_PORT}|${TLS_INTERNAL_PORT}|g" \
     -e "s|\${MINDIFF}|${MINDIFF}|g" \
     -e "s|\${STARTDIFF}|${STARTDIFF}|g" \
     -e "s|\${MAXDIFF}|${MAXDIFF}|g" \

ui/src/format.ts

@@ -1,6 +1,8 @@
 // Formatters for hashrate, share difficulty, time, and miner hardware
 // detection from stratum user-agent strings. Pure functions, no DOM.
 
+import type { StratumServer } from "./types";
+
 const HASHRATE_UNITS = ["H/s", "kH/s", "MH/s", "GH/s", "TH/s", "PH/s", "EH/s"];
 
 export function formatHashrate(hs: number): string {
@@ -100,6 +102,26 @@ export function explorerBaseFor(
   return "https://mempool.space";
 }
 
+// Resolve how a miner is connected from its ckpool serverurl[] index.
+//
+// The deployment declares the bind array via STRATUM_SERVERS (the StartOS
+// wrapper renders one entry per bind it configures). When it hasn't — the
+// dev compose stack, or an older wrapper — fall back to the historical
+// layout, where index 0 is the plaintext bind and anything else is the
+// loopback bind that stunnel forwards TLS traffic to.
+export function connectionOf(
+  serverIndex: number | undefined,
+  servers: StratumServer[] | undefined,
+): { tls: boolean; label: string } {
+  const declared = servers?.[serverIndex ?? 0];
+  if (declared) {
+    return { tls: declared.kind !== "plain", label: declared.label };
+  }
+  return serverIndex
+    ? { tls: true, label: "Encrypted connection via TLS" }
+    : { tls: false, label: "Unencrypted connection" };
+}
+
 // Detect common Bitcoin mining hardware from the stratum useragent
 // string. This is a best-effort heuristic; unknown agents fall back
 // to a stripped version of the raw string. Order matters — check

ui/src/lib/MinersTable.svelte

@@ -8,6 +8,7 @@
     detectHardware,
     isOpenSource,
     btcAddressOf,
+    connectionOf,
   } from "../format";
   import type { StratumClient, Worker } from "../types";
 
@@ -18,6 +19,7 @@
     hardware: string;
     openSource: boolean;
     tls: boolean;
+    tlsLabel: string;
     hashrate1m: number;
     hashrate1h: number;
     bestSession: number;
@@ -35,9 +37,10 @@
   // from the joined worker_instance, which ckpool keys by full
   // workername with user = the BTC.
   //
-  // ckpool's serverurl array gives us a second piece of info: TLS
+  // ckpool's serverurl array gives us a second piece of info: which
-  // traffic comes in via stunnel on the loopback-only bind (server
+  // bind the connection arrived on. connectionOf() maps that index to
-  // index 1), so client.server === 1 means this miner is using TLS.
+  // the transport the deployment declared, so the lock badge can name
+  // the certificate in play rather than just "encrypted".
   const rows = $derived.by<Row[]>(() => {
     const clients = snap.data?.clients ?? [];
     const workers = snap.data?.workers ?? [];
@@ -52,13 +55,15 @@
       seen.add(wname);
       const w = byWorker.get(wname);
       const btcAddress = w?.user ?? btcAddressOf(wname);
+      const conn = connectionOf(c.server, snap.data?.stratum_servers);
       out.push({
         workerName: wname,
         btcAddress,
         sourceIp: c.address,
         hardware: detectHardware(c.useragent),
         openSource: isOpenSource(c.useragent),
-        tls: c.server === 1,
+        tls: conn.tls,
+        tlsLabel: conn.label,
         hashrate1m: c.dsps1 * 2 ** 32,
         hashrate1h: c.dsps60 * 2 ** 32,
         bestSession: c.bestdiff,
@@ -79,6 +84,7 @@
         hardware: "offline",
         openSource: false,
         tls: false,
+        tlsLabel: "",
         hashrate1m: 0,
         hashrate1h: 0,
         bestSession: 0,
@@ -133,7 +139,7 @@
                     title="View per-worker stats"
                   >{r.workerName}</button>
                   {#if r.tls}
-                    <span class="badge tls" title="Encrypted connection via TLS">
+                    <span class="badge tls" title={r.tlsLabel}>
                       <svg viewBox="0 0 16 16" aria-hidden="true">
                         <path d="M8 1a3.5 3.5 0 0 0-3.5 3.5V7H4a1.5 1.5 0 0 0-1.5 1.5v5A1.5 1.5 0 0 0 4 15h8a1.5 1.5 0 0 0 1.5-1.5v-5A1.5 1.5 0 0 0 12 7h-.5V4.5A3.5 3.5 0 0 0 8 1Zm2 6H6V4.5a2 2 0 1 1 4 0V7Z"/>
                       </svg>

ui/src/lib/UserDetailPage.svelte

@@ -8,6 +8,7 @@
     detectHardware,
     isOpenSource,
     explorerBaseFor,
+    connectionOf,
   } from "../format";
   import type { Worker, StratumClient } from "../types";
 
@@ -46,6 +47,7 @@
       hardware: string;
       openSource: boolean;
       tls: boolean;
+      tlsLabel: string;
       sourceIp: string;
       hashrate1m: number;
       hashrate1h: number;
@@ -64,7 +66,10 @@
         worker: w.worker,
         hardware: c ? detectHardware(c.useragent) : "offline",
         openSource: c ? isOpenSource(c.useragent) : false,
-        tls: c?.server === 1,
+        tls: !!c && connectionOf(c.server, snap.data?.stratum_servers).tls,
+        tlsLabel: c
+          ? connectionOf(c.server, snap.data?.stratum_servers).label
+          : "",
         sourceIp: c?.address ?? "",
         hashrate1m: c ? c.dsps1 * 2 ** 32 : 0,
         hashrate1h: c ? c.dsps60 * 2 ** 32 : 0,
@@ -85,7 +90,8 @@
         worker: wname,
         hardware: detectHardware(c.useragent),
         openSource: isOpenSource(c.useragent),
-        tls: c.server === 1,
+        tls: connectionOf(c.server, snap.data?.stratum_servers).tls,
+        tlsLabel: connectionOf(c.server, snap.data?.stratum_servers).label,
         sourceIp: c.address,
         hashrate1m: c.dsps1 * 2 ** 32,
         hashrate1h: c.dsps60 * 2 ** 32,
@@ -232,7 +238,7 @@
                       title="View per-worker stats"
                     >{r.worker}</button>
                     {#if r.tls}
-                      <span class="badge tls" title="Encrypted connection via TLS">
+                      <span class="badge tls" title={r.tlsLabel}>
                         <svg viewBox="0 0 16 16" aria-hidden="true">
                           <path d="M8 1a3.5 3.5 0 0 0-3.5 3.5V7H4a1.5 1.5 0 0 0-1.5 1.5v5A1.5 1.5 0 0 0 4 15h8a1.5 1.5 0 0 0 1.5-1.5v-5A1.5 1.5 0 0 0 12 7h-.5V4.5A3.5 3.5 0 0 0 8 1Zm2 6H6V4.5a2 2 0 1 1 4 0V7Z"/>
                         </svg>

ui/src/lib/WorkerDetailPage.svelte

@@ -9,6 +9,7 @@
     detectHardware,
     isOpenSource,
     btcAddressOf,
+    connectionOf,
   } from "../format";
   import type { Worker, StratumClient } from "../types";
 
@@ -29,7 +30,12 @@
   const idle = $derived(client?.idle ?? worker?.idle ?? false);
   const hardware = $derived(client ? detectHardware(client.useragent) : "offline");
   const openSource = $derived(client ? isOpenSource(client.useragent) : false);
-  const tls = $derived(client?.server === 1);
+  const conn = $derived(
+    client
+      ? connectionOf(client.server, snap.data?.stratum_servers)
+      : { tls: false, label: "" },
+  );
+  const tls = $derived(conn.tls);
 
   const hs1m = $derived(client ? client.dsps1 * 2 ** 32 : 0);
   const hs5m = $derived(client ? client.dsps5 * 2 ** 32 : 0);
@@ -88,7 +94,7 @@
         title="View per-user stats"
       >{btcAddress}</button>
       {#if tls}
-        <span class="badge tls" title="Encrypted connection via TLS">
+        <span class="badge tls" title={conn.label}>
           <svg viewBox="0 0 16 16" aria-hidden="true">
             <path d="M8 1a3.5 3.5 0 0 0-3.5 3.5V7H4a1.5 1.5 0 0 0-1.5 1.5v5A1.5 1.5 0 0 0 4 15h8a1.5 1.5 0 0 0 1.5-1.5v-5A1.5 1.5 0 0 0 12 7h-.5V4.5A3.5 3.5 0 0 0 8 1Zm2 6H6V4.5a2 2 0 1 1 4 0V7Z"/>
           </svg>

ui/src/types.ts

@@ -71,9 +71,10 @@ export type StratumClient = {
   workername: string;
   userid: number;
   // Index into ckpool's serverurl[] array; identifies which stratum
-  // bind the client connected on. We use this to tag TLS clients:
+  // bind the client connected on. What each index *means* depends on
-  // index 0 is the public plaintext bind, index 1 is the loopback-only
+  // how the deployment rendered ckpool.conf, so resolve it through
-  // bind that stunnel forwards TLS traffic to.
+  // Snapshot.stratum_servers rather than hardcoding — see
+  // connectionOf() in format.ts.
   server: number;
   bestdiff: number;
 };
@@ -112,6 +113,16 @@ export type HashratePoint = {
   v: number; // H/s
 };
 
+// One entry per ckpool serverurl[] bind, declared by the deployment via
+// the STRATUM_SERVERS env. `kind` is the stable tag the UI switches on;
+// `label` is free text shown on hover.
+export type StratumServerKind = "plain" | "tls-local" | "tls-public";
+
+export type StratumServer = {
+  kind: StratumServerKind;
+  label: string;
+};
+
 export type Snapshot = {
   generated_at: string;
   pool: PoolStats | null;
@@ -137,6 +148,10 @@ export type Snapshot = {
   // Optional override for explorer links. Empty/undefined means the
   // UI falls back to its mempool.space defaults.
   mempool_base_url?: string;
+  // Describes ckpool's serverurl[] binds: entry N says what a client
+  // with `server === N` is connected over. Undefined when the
+  // deployment didn't declare them — see connectionOf() in format.ts.
+  stratum_servers?: StratumServer[];
   // Submission attempt tracking — count of "Possible block solve"
   // log lines vs "Solved and confirmed" lines. A growing gap means
   // submissions are being rejected by bitcoind.