diff --git a/components/profile-modal.html b/components/profile-modal.html
index 9ba53b51..62583aee 100644
--- a/components/profile-modal.html
+++ b/components/profile-modal.html
@@ -664,6 +664,44 @@
                 </div>
               </div>
               <ul id="relayList" class="grid-stack" data-orientation="vertical"></ul>
+              <div id="relayHealthPanel" class="card space-y-4 p-5">
+                <div class="flex flex-wrap items-start justify-between gap-3">
+                  <div class="space-y-1">
+                    <h3 class="text-base font-semibold text-text">Relay health</h3>
+                    <p class="text-sm text-muted">
+                      Monitor connectivity, latency, and errors for your configured relays.
+                    </p>
+                  </div>
+                  <button
+                    id="relayHealthRefreshBtn"
+                    type="button"
+                    class="btn-ghost focus-ring text-xs"
+                  >
+                    Refresh
+                  </button>
+                </div>
+                <label
+                  for="relayHealthTelemetryOptIn"
+                  class="inline-flex items-center gap-2 text-xs font-medium text-muted-strong"
+                >
+                  <input
+                    id="relayHealthTelemetryOptIn"
+                    type="checkbox"
+                    class="checkbox"
+                  />
+                  Share relay health telemetry
+                </label>
+                <p class="text-xs text-muted">
+                  Telemetry is opt-in and only includes relay URLs, latency, and error counts.
+                </p>
+                <ul id="relayHealthList" class="grid-stack" data-orientation="vertical"></ul>
+                <p
+                  id="relayHealthStatus"
+                  class="text-xs text-muted"
+                  role="status"
+                  aria-live="polite"
+                ></p>
+              </div>
             </section>
 
             <section
diff --git a/js/nostr/client.js b/js/nostr/client.js
index c5e0ddce..b4f8b75a 100644
--- a/js/nostr/client.js
+++ b/js/nostr/client.js
@@ -116,6 +116,10 @@ import {
   decryptDmInWorker,
   isDmDecryptWorkerSupported,
 } from "./dmDecryptWorkerClient.js";
+import {
+  sanitizeDecryptError,
+  summarizeDmEventForLog,
+} from "./dmDecryptDiagnostics.js";
 import { devLogger, userLogger } from "../utils/logger.js";
 import { LRUCache } from "../utils/lruCache.js";
 import { updateConversationFromMessage, writeMessages } from "../storage/dmDb.js";
@@ -4177,8 +4181,8 @@ export class NostrClient {
       result = await decryptDM(event, context);
     } catch (error) {
       devLogger.warn("[nostr] DM decryptor threw unexpectedly.", {
-        error,
-        eventId,
+        error: sanitizeDecryptError(error),
+        event: summarizeDmEventForLog(event),
       });
       throw error;
     }
@@ -4262,8 +4266,8 @@ export class NostrClient {
         }
       } catch (error) {
         devLogger.warn("[nostr] Failed to decrypt DM event during list.", {
-          error,
-          id: event?.id || null,
+          error: sanitizeDecryptError(error),
+          event: summarizeDmEventForLog(event),
         });
       }
     }
@@ -4349,8 +4353,8 @@ export class NostrClient {
             devLogger.warn(
               "[nostr] Failed to decrypt DM event from subscription.",
               {
-                error,
-                id: eventId,
+                error: sanitizeDecryptError(error),
+                event: summarizeDmEventForLog(event),
               },
             );
           }
diff --git a/js/nostr/dmDecryptDiagnostics.js b/js/nostr/dmDecryptDiagnostics.js
new file mode 100644
index 00000000..c6e5fb51
--- /dev/null
+++ b/js/nostr/dmDecryptDiagnostics.js
@@ -0,0 +1,42 @@
+export function summarizeDmEventForLog(event) {
+  if (!event || typeof event !== "object") {
+    return {
+      kind: null,
+      createdAt: null,
+      hasContent: false,
+      contentLength: 0,
+      tagCount: 0,
+    };
+  }
+
+  const createdAt = Number.isFinite(event.created_at)
+    ? Math.floor(event.created_at)
+    : null;
+
+  return {
+    kind: Number.isFinite(event.kind) ? event.kind : null,
+    createdAt,
+    hasContent: typeof event.content === "string" && event.content.length > 0,
+    contentLength: typeof event.content === "string" ? event.content.length : 0,
+    tagCount: Array.isArray(event.tags) ? event.tags.length : 0,
+  };
+}
+
+export function sanitizeDecryptError(error) {
+  if (!error) {
+    return null;
+  }
+
+  const message =
+    typeof error.message === "string"
+      ? error.message
+      : typeof error === "string"
+      ? error
+      : "";
+
+  return {
+    name: typeof error.name === "string" ? error.name : "",
+    code: typeof error.code === "string" ? error.code : "",
+    message,
+  };
+}
diff --git a/js/services/relayHealthService.js b/js/services/relayHealthService.js
new file mode 100644
index 00000000..87ed52fc
--- /dev/null
+++ b/js/services/relayHealthService.js
@@ -0,0 +1,236 @@
+import { devLogger, userLogger } from "../utils/logger.js";
+
+const TELEMETRY_STORAGE_KEY = "bitvid:relay-health-telemetry-opt-in";
+
+function resolveLogger(logger) {
+  if (logger && logger.dev && logger.user) {
+    return logger;
+  }
+  return { dev: devLogger, user: userLogger };
+}
+
+function nowMs() {
+  return typeof performance !== "undefined" && performance.now
+    ? performance.now()
+    : Date.now();
+}
+
+function readTelemetryOptIn() {
+  if (typeof window === "undefined") {
+    return false;
+  }
+
+  try {
+    const stored = window.localStorage.getItem(TELEMETRY_STORAGE_KEY);
+    return stored === "true";
+  } catch (error) {
+    userLogger.warn(
+      "[relayHealth] Failed to read telemetry preference from storage.",
+      error,
+    );
+    return false;
+  }
+}
+
+function writeTelemetryOptIn(nextValue) {
+  if (typeof window === "undefined") {
+    return;
+  }
+
+  try {
+    window.localStorage.setItem(
+      TELEMETRY_STORAGE_KEY,
+      nextValue ? "true" : "false",
+    );
+  } catch (error) {
+    userLogger.warn(
+      "[relayHealth] Failed to persist telemetry preference.",
+      error,
+    );
+  }
+}
+
+class RelayHealthService {
+  constructor({ relayManager, nostrClient, logger, telemetryEmitter } = {}) {
+    this.relayManager = relayManager || null;
+    this.nostrClient = nostrClient || null;
+    this.logger = resolveLogger(logger);
+    this.telemetryEmitter =
+      typeof telemetryEmitter === "function" ? telemetryEmitter : null;
+    this.relayStates = new Map();
+    this.attachedRelays = new Set();
+    this.cachedTelemetryOptIn = readTelemetryOptIn();
+  }
+
+  getTelemetryOptIn() {
+    return this.cachedTelemetryOptIn;
+  }
+
+  setTelemetryOptIn(value) {
+    const normalized = Boolean(value);
+    this.cachedTelemetryOptIn = normalized;
+    writeTelemetryOptIn(normalized);
+    return normalized;
+  }
+
+  getRelayUrls() {
+    if (!this.relayManager || typeof this.relayManager.getEntries !== "function") {
+      return [];
+    }
+    const entries = this.relayManager.getEntries();
+    return entries
+      .map((entry) => (typeof entry?.url === "string" ? entry.url.trim() : ""))
+      .filter(Boolean);
+  }
+
+  ensureRelayState(relayUrl) {
+    if (!this.relayStates.has(relayUrl)) {
+      this.relayStates.set(relayUrl, {
+        url: relayUrl,
+        connected: false,
+        lastLatencyMs: null,
+        errorCount: 0,
+        lastCheckedAt: null,
+        lastErrorAt: null,
+      });
+    }
+
+    return this.relayStates.get(relayUrl);
+  }
+
+  attachRelayListeners(relayUrl, relay) {
+    if (!relay || typeof relay.on !== "function") {
+      return;
+    }
+    if (this.attachedRelays.has(relayUrl)) {
+      return;
+    }
+
+    try {
+      relay.on("connect", () => {
+        this.recordRelaySuccess(relayUrl, null);
+      });
+      relay.on("disconnect", () => {
+        this.recordRelayFailure(relayUrl, new Error("relay-disconnect"));
+      });
+      relay.on("error", (error) => {
+        this.recordRelayFailure(relayUrl, error);
+      });
+      this.attachedRelays.add(relayUrl);
+    } catch (error) {
+      this.logger.dev.warn(
+        "[relayHealth] Failed to attach relay listeners.",
+        error,
+      );
+    }
+  }
+
+  recordRelaySuccess(relayUrl, latencyMs) {
+    const state = this.ensureRelayState(relayUrl);
+    state.connected = true;
+    state.lastCheckedAt = Date.now();
+    if (Number.isFinite(latencyMs)) {
+      state.lastLatencyMs = Math.max(0, Math.round(latencyMs));
+    }
+  }
+
+  recordRelayFailure(relayUrl, error) {
+    const state = this.ensureRelayState(relayUrl);
+    state.connected = false;
+    state.errorCount += 1;
+    state.lastCheckedAt = Date.now();
+    state.lastErrorAt = Date.now();
+
+    this.logger.dev.warn("[relayHealth] Relay check failed.", {
+      relayUrl,
+      error,
+    });
+  }
+
+  async checkRelay(relayUrl) {
+    if (!relayUrl) {
+      return;
+    }
+
+    if (!this.nostrClient) {
+      this.recordRelayFailure(relayUrl, new Error("nostr-client-unavailable"));
+      return;
+    }
+
+    try {
+      if (typeof this.nostrClient.ensurePool === "function") {
+        await this.nostrClient.ensurePool();
+      }
+    } catch (error) {
+      this.recordRelayFailure(relayUrl, error);
+      return;
+    }
+
+    if (!this.nostrClient.pool || typeof this.nostrClient.pool.ensureRelay !== "function") {
+      this.recordRelayFailure(relayUrl, new Error("relay-pool-unavailable"));
+      return;
+    }
+
+    const start = nowMs();
+    try {
+      const relay = await this.nostrClient.pool.ensureRelay(relayUrl);
+      if (!relay) {
+        throw new Error("relay-unavailable");
+      }
+
+      this.attachRelayListeners(relayUrl, relay);
+      this.recordRelaySuccess(relayUrl, nowMs() - start);
+    } catch (error) {
+      this.recordRelayFailure(relayUrl, error);
+    }
+  }
+
+  getSnapshot(relayUrls = null) {
+    const urls = Array.isArray(relayUrls) ? relayUrls : this.getRelayUrls();
+    return urls.map((url) => ({ ...this.ensureRelayState(url) }));
+  }
+
+  async refresh(relayUrls = null) {
+    const urls = Array.isArray(relayUrls) ? relayUrls : this.getRelayUrls();
+    if (!urls.length) {
+      return [];
+    }
+
+    await Promise.allSettled(urls.map((url) => this.checkRelay(url)));
+    const snapshot = this.getSnapshot(urls);
+    this.emitTelemetry(snapshot);
+    return snapshot;
+  }
+
+  emitTelemetry(snapshot) {
+    if (!this.telemetryEmitter || !this.getTelemetryOptIn()) {
+      return;
+    }
+
+    const payload = {
+      sampledAt: Date.now(),
+      relays: Array.isArray(snapshot)
+        ? snapshot.map((entry) => ({
+            url: entry.url,
+            connected: Boolean(entry.connected),
+            latencyMs:
+              Number.isFinite(entry.lastLatencyMs) ? entry.lastLatencyMs : null,
+            errorCount: Number.isFinite(entry.errorCount)
+              ? entry.errorCount
+              : 0,
+          }))
+        : [],
+    };
+
+    try {
+      this.telemetryEmitter("relay_health_snapshot", payload);
+    } catch (error) {
+      this.logger.user.warn(
+        "[relayHealth] Failed to emit relay health telemetry.",
+        error,
+      );
+    }
+  }
+}
+
+export default RelayHealthService;
diff --git a/js/ui/applicationBootstrap.js b/js/ui/applicationBootstrap.js
index 948be196..9d21d8f3 100644
--- a/js/ui/applicationBootstrap.js
+++ b/js/ui/applicationBootstrap.js
@@ -17,6 +17,7 @@ import nostrService from "../services/nostrService.js";
 import storageService from "../services/storageService.js";
 import watchHistoryService from "../watchHistoryService.js";
 import r2Service from "../services/r2Service.js";
+import RelayHealthService from "../services/relayHealthService.js";
 import { createFeedEngine } from "../feedEngine/index.js";
 import { URL_FIRST_ENABLED } from "../constants.js";
 import { ALLOW_NSFW_CONTENT } from "../config.js";
@@ -426,6 +427,12 @@ export default class ApplicationBootstrap {
     const modalContainer = doc?.getElementById("modalContainer") || null;
     try {
       if (modalContainer) {
+        const relayHealthService = new RelayHealthService({
+          relayManager,
+          nostrClient,
+          telemetryEmitter: (eventName, payload) =>
+            app.emitTelemetryEvent(eventName, payload),
+        });
         const profileModalServices = {
           normalizeHexPubkey: (value) => app.normalizeHexPubkey(value),
           safeEncodeNpub: (pubkey) => app.safeEncodeNpub(pubkey),
@@ -480,6 +487,7 @@ export default class ApplicationBootstrap {
             app.describeHashtagPreferencesError(error, {
               fallbackMessage,
             }),
+          relayHealthService,
           log: (...args) => app.log(...args),
           closeAllMoreMenus: (options) => app.closeAllMoreMenus(options),
           clipboard:
diff --git a/js/ui/profileModalController.js b/js/ui/profileModalController.js
index 50b7eaa7..dd37ca75 100644
--- a/js/ui/profileModalController.js
+++ b/js/ui/profileModalController.js
@@ -1241,6 +1241,12 @@ export class ProfileModalController {
     this.relayInput = null;
     this.addRelayButton = null;
     this.restoreRelaysButton = null;
+    this.relayHealthPanel = null;
+    this.relayHealthList = null;
+    this.relayHealthStatus = null;
+    this.relayHealthRefreshButton = null;
+    this.relayHealthTelemetryToggle = null;
+    this.relayHealthRefreshPromise = null;
     this.profileRelayList = null;
     this.profileRelayInput = null;
     this.profileAddRelayBtn = null;
@@ -1521,6 +1527,16 @@ export class ProfileModalController {
     this.addRelayButton = document.getElementById("addRelayBtn") || null;
     this.restoreRelaysButton =
       document.getElementById("restoreRelaysBtn") || null;
+    this.relayHealthPanel =
+      document.getElementById("relayHealthPanel") || null;
+    this.relayHealthList =
+      document.getElementById("relayHealthList") || null;
+    this.relayHealthStatus =
+      document.getElementById("relayHealthStatus") || null;
+    this.relayHealthRefreshButton =
+      document.getElementById("relayHealthRefreshBtn") || null;
+    this.relayHealthTelemetryToggle =
+      document.getElementById("relayHealthTelemetryOptIn") || null;
 
     this.subscriptionList =
       document.getElementById("subscriptionsList") || null;
@@ -4188,6 +4204,18 @@ export class ProfileModalController {
       });
     }
 
+    if (this.relayHealthRefreshButton instanceof HTMLElement) {
+      this.relayHealthRefreshButton.addEventListener("click", () => {
+        void this.refreshRelayHealthPanel({ forceRefresh: true, reason: "manual" });
+      });
+    }
+
+    if (this.relayHealthTelemetryToggle instanceof HTMLInputElement) {
+      this.relayHealthTelemetryToggle.addEventListener("change", () => {
+        this.handleRelayHealthTelemetryToggle();
+      });
+    }
+
     if (this.addBlockedButton instanceof HTMLElement) {
       this.addBlockedButton.addEventListener("click", () => {
         void this.handleAddBlockedCreator();
@@ -5828,6 +5856,9 @@ export class ProfileModalController {
 
     if (target === "history") {
       void this.populateProfileWatchHistory();
+    } else if (target === "relays") {
+      this.populateProfileRelays();
+      void this.refreshRelayHealthPanel({ forceRefresh: true, reason: "pane-select" });
     } else if (target === "messages") {
       this.resumeProfileMessages();
       void this.populateProfileMessages({ reason: "pane-select" });
@@ -5949,6 +5980,166 @@ export class ProfileModalController {
     });
   }
 
+  updateRelayHealthStatus(message = "") {
+    if (!this.relayHealthStatus) {
+      return;
+    }
+
+    const text = typeof message === "string" ? message.trim() : "";
+    this.relayHealthStatus.textContent = text;
+  }
+
+  renderRelayHealthSnapshot(snapshot = []) {
+    if (!this.relayHealthList) {
+      return;
+    }
+
+    this.relayHealthList.innerHTML = "";
+
+    if (!snapshot.length) {
+      const emptyState = document.createElement("li");
+      emptyState.className =
+        "card border border-dashed border-surface-strong p-4 text-center text-sm text-muted";
+      emptyState.textContent = "No relays configured.";
+      this.relayHealthList.appendChild(emptyState);
+      return;
+    }
+
+    snapshot.forEach((entry) => {
+      const item = document.createElement("li");
+      item.className = "card flex flex-col gap-2 p-4";
+
+      const header = document.createElement("div");
+      header.className = "flex items-center justify-between gap-3";
+
+      const urlEl = document.createElement("p");
+      urlEl.className = "text-sm font-medium text-primary break-all";
+      urlEl.textContent = entry.url;
+
+      const connection = document.createElement("span");
+      const connected = Boolean(entry.connected);
+      connection.className = `text-xs font-semibold ${
+        connected ? "text-status-success" : "text-status-danger"
+      }`;
+      connection.textContent = connected ? "Connected" : "Unavailable";
+
+      header.appendChild(urlEl);
+      header.appendChild(connection);
+
+      const details = document.createElement("div");
+      details.className = "grid grid-cols-2 gap-3 text-xs text-muted sm:grid-cols-3";
+
+      const latency = document.createElement("div");
+      latency.className = "flex items-center justify-between gap-2";
+      const latencyLabel = document.createElement("span");
+      latencyLabel.textContent = "Latency";
+      const latencyValue = document.createElement("span");
+      latencyValue.className = "text-text";
+      latencyValue.textContent = Number.isFinite(entry.lastLatencyMs)
+        ? `${entry.lastLatencyMs} ms`
+        : "—";
+      latency.appendChild(latencyLabel);
+      latency.appendChild(latencyValue);
+
+      const errors = document.createElement("div");
+      errors.className = "flex items-center justify-between gap-2";
+      const errorsLabel = document.createElement("span");
+      errorsLabel.textContent = "Errors";
+      const errorsValue = document.createElement("span");
+      errorsValue.className = "text-text";
+      errorsValue.textContent = Number.isFinite(entry.errorCount)
+        ? `${entry.errorCount}`
+        : "0";
+      errors.appendChild(errorsLabel);
+      errors.appendChild(errorsValue);
+
+      const checks = document.createElement("div");
+      checks.className = "flex items-center justify-between gap-2";
+      const checksLabel = document.createElement("span");
+      checksLabel.textContent = "Checked";
+      const checksValue = document.createElement("span");
+      checksValue.className = "text-text";
+      if (Number.isFinite(entry.lastCheckedAt) && entry.lastCheckedAt > 0) {
+        checksValue.textContent = new Date(entry.lastCheckedAt).toLocaleTimeString();
+      } else {
+        checksValue.textContent = "—";
+      }
+      checks.appendChild(checksLabel);
+      checks.appendChild(checksValue);
+
+      details.appendChild(latency);
+      details.appendChild(errors);
+      details.appendChild(checks);
+
+      item.appendChild(header);
+      item.appendChild(details);
+
+      this.relayHealthList.appendChild(item);
+    });
+  }
+
+  handleRelayHealthTelemetryToggle() {
+    const service = this.services?.relayHealthService;
+    if (!service || !(this.relayHealthTelemetryToggle instanceof HTMLInputElement)) {
+      return;
+    }
+
+    const enabled = service.setTelemetryOptIn(
+      this.relayHealthTelemetryToggle.checked,
+    );
+    this.relayHealthTelemetryToggle.checked = enabled;
+    this.updateRelayHealthStatus(
+      enabled ? "Relay health telemetry enabled." : "Relay health telemetry disabled.",
+    );
+  }
+
+  async refreshRelayHealthPanel({ forceRefresh = false, reason = "" } = {}) {
+    const service = this.services?.relayHealthService;
+    if (!service || !this.relayHealthList) {
+      return [];
+    }
+
+    if (this.relayHealthTelemetryToggle instanceof HTMLInputElement) {
+      this.relayHealthTelemetryToggle.checked = service.getTelemetryOptIn();
+    }
+
+    const snapshot = service.getSnapshot();
+    this.renderRelayHealthSnapshot(snapshot);
+
+    if (!forceRefresh) {
+      return snapshot;
+    }
+
+    if (this.relayHealthRefreshPromise) {
+      return this.relayHealthRefreshPromise;
+    }
+
+    const statusMessage = reason === "manual" ? "Refreshing relay health…" : "Checking relays…";
+    this.updateRelayHealthStatus(statusMessage);
+
+    const refreshPromise = service
+      .refresh()
+      .then((latest) => {
+        this.renderRelayHealthSnapshot(latest);
+        this.updateRelayHealthStatus("Relay health updated.");
+        return latest;
+      })
+      .catch((error) => {
+        this.updateRelayHealthStatus("Failed to refresh relay health.");
+        this.showError("Failed to refresh relay health.");
+        devLogger.warn("[profileModal] Relay health refresh failed:", error);
+        return [];
+      })
+      .finally(() => {
+        if (this.relayHealthRefreshPromise === refreshPromise) {
+          this.relayHealthRefreshPromise = null;
+        }
+      });
+
+    this.relayHealthRefreshPromise = refreshPromise;
+    return refreshPromise;
+  }
+
   async handleRelayOperation(meta = {}, {
     successMessage = "Relay preferences updated.",
     skipPublishIfUnchanged = true,
@@ -6010,10 +6201,12 @@ export class ProfileModalController {
         this.showSuccess(unchangedMessage);
       }
       this.populateProfileRelays();
+      void this.refreshRelayHealthPanel({ forceRefresh: true, reason: "relay-update" });
       return operationContext;
     }
 
     this.populateProfileRelays();
+    void this.refreshRelayHealthPanel({ forceRefresh: true, reason: "relay-update" });
 
     if (operationContext.ok) {
       if (successMessage) {