diff --git a/src/lib/index-relay-http.test.ts b/src/lib/index-relay-http.test.ts
new file mode 100644
index 00000000..66765100
--- /dev/null
+++ b/src/lib/index-relay-http.test.ts
@@ -0,0 +1,28 @@
+import {
+  IndexRelayTransportError,
+  clearDevIndexRelayUnavailableThisSession,
+  isDevIndexRelayUnavailableThisSession,
+  isIndexRelayTransportFailure
+} from '@/lib/index-relay-http'
+import { describe, expect, it, beforeEach } from 'vitest'
+
+describe('isIndexRelayTransportFailure', () => {
+  it('treats IndexRelayTransportError as transport failure', () => {
+    expect(isIndexRelayTransportFailure(new IndexRelayTransportError())).toBe(true)
+    expect(isIndexRelayTransportFailure(new IndexRelayTransportError(new Error('HTTP 500')))).toBe(true)
+  })
+
+  it('treats network TypeError as transport failure', () => {
+    expect(isIndexRelayTransportFailure(new TypeError('Failed to fetch'))).toBe(true)
+  })
+})
+
+describe('dev index relay session skip', () => {
+  beforeEach(() => {
+    clearDevIndexRelayUnavailableThisSession()
+  })
+
+  it('starts available after clear', () => {
+    expect(isDevIndexRelayUnavailableThisSession()).toBe(false)
+  })
+})
diff --git a/src/lib/index-relay-http.ts b/src/lib/index-relay-http.ts
index a739d43a..226b705c 100644
--- a/src/lib/index-relay-http.ts
+++ b/src/lib/index-relay-http.ts
@@ -79,6 +79,7 @@ function warnIndexRelayHttpThrottled(endpoint: string, message: string, meta: Re
 
 /** True when the relay cannot be reached (down, DNS, browser blocked, etc.). Not HTTP 4xx/5xx from a live server. */
 export function isIndexRelayTransportFailure(err: unknown): boolean {
+  if (err instanceof IndexRelayTransportError) return true
   if (err == null || typeof err !== 'object') return false
   const e = err as Error & { name?: string; cause?: unknown }
   if (e.name === 'AbortError') return false
@@ -107,6 +108,39 @@ function isDevViteIndexRelayProxyPath(endpoint: string): boolean {
   )
 }
 
+/**
+ * When the Vite `/dev-index-relay` proxy returns 5xx, skip further dev index HTTP fetches for this tab
+ * (same pattern as optional `/sites/` and translate proxies). Cleared on a successful filter response.
+ */
+let devIndexRelayUnavailableThisSession = false
+let devIndexRelaySkipLogged = false
+
+export function isDevIndexRelayUnavailableThisSession(): boolean {
+  return devIndexRelayUnavailableThisSession
+}
+
+export function clearDevIndexRelayUnavailableThisSession(): void {
+  devIndexRelayUnavailableThisSession = false
+  devIndexRelaySkipLogged = false
+}
+
+function markDevIndexRelayUnavailableFromHttpStatus(status: number, endpoint: string): void {
+  if (!isDevViteIndexRelayProxyPath(endpoint)) return
+  if (status < 500 || status > 599) return
+  if (devIndexRelayUnavailableThisSession) return
+  devIndexRelayUnavailableThisSession = true
+  if (!devIndexRelaySkipLogged) {
+    devIndexRelaySkipLogged = true
+    logger.debug(
+      `[IndexRelayHttp] Dev index relay returned HTTP ${status}; skipping further dev-index-relay fetches this session (other relays continue).`
+    )
+  }
+}
+
+function shouldSkipDevIndexRelayFetch(endpoint: string): boolean {
+  return import.meta.env.DEV && devIndexRelayUnavailableThisSession && isDevViteIndexRelayProxyPath(endpoint)
+}
+
 function maybeLogDevIndexRelayUnreachableHint(): void {
   if (import.meta.env.PROD || typeof window === 'undefined') return
   const now = Date.now()
@@ -191,6 +225,9 @@ export async function queryIndexRelay(
   const filters = Array.isArray(filter) ? filter : [filter]
   const out: NEvent[] = []
   const seen = new Set<string>()
+  if (shouldSkipDevIndexRelayFetch(endpoint)) {
+    return out
+  }
   for (const f of filters) {
     const body = nostrFilterToIndexRelayBody(filterForIndexRelay(f))
     try {
@@ -213,6 +250,7 @@ export async function queryIndexRelay(
             /* ignore */
           }
           if (res.status >= 500 && res.status <= 599) {
+            markDevIndexRelayUnavailableFromHttpStatus(res.status, endpoint)
             maybeLogDevIndexRelayHttpErrorHint(res.status, detail || undefined)
           } else {
             logger.debug('[IndexRelayHttp] filter HTTP response', {
@@ -228,10 +266,12 @@ export async function queryIndexRelay(
           })
         }
         if (res.status >= 500) {
+          markDevIndexRelayUnavailableFromHttpStatus(res.status, endpoint)
           throw new IndexRelayTransportError(new Error(`HTTP ${res.status}`))
         }
         continue
       }
+      clearDevIndexRelayUnavailableThisSession()
       const json = (await res.json()) as { data?: unknown }
       const data = json.data
       if (!Array.isArray(data)) continue
@@ -245,11 +285,12 @@ export async function queryIndexRelay(
       }
     } catch (e) {
       if ((e as Error).name === 'AbortError') throw e
+      if (e instanceof IndexRelayTransportError) throw e
       if (isIndexRelayTransportFailure(e)) {
         handleFilterTransportFailure(endpoint, e)
-      } else {
-        warnIndexRelayHttpThrottled(endpoint, '[IndexRelayHttp] filter request error', { endpoint, error: e })
+        throw new IndexRelayTransportError(e)
       }
+      warnIndexRelayHttpThrottled(endpoint, '[IndexRelayHttp] filter request error', { endpoint, error: e })
     }
   }
   return out
diff --git a/src/lib/relay-strikes.test.ts b/src/lib/relay-strikes.test.ts
index 0c0c717c..3b00ab53 100644
--- a/src/lib/relay-strikes.test.ts
+++ b/src/lib/relay-strikes.test.ts
@@ -43,6 +43,20 @@ describe('relaySessionStrikes.observeSubscribeBatch', () => {
   })
 })
 
+describe('relaySessionStrikes HTTP read failures', () => {
+  beforeEach(() => {
+    relaySessionStrikes.reset()
+  })
+
+  it('session-skips after five parallel HTTP failures (no debounce)', () => {
+    const url = 'https://index.example.com/'
+    for (let i = 0; i < 5; i++) {
+      relaySessionStrikes.recordReadFailure(url, 'http')
+    }
+    expect(relaySessionStrikes.isReadHttpSkipped(url)).toBe(true)
+  })
+})
+
 describe('relaySessionStrikes.clearKey', () => {
   beforeEach(() => {
     relaySessionStrikes.reset()
diff --git a/src/lib/relay-strikes.ts b/src/lib/relay-strikes.ts
index fe0b0c10..e287ea3e 100644
--- a/src/lib/relay-strikes.ts
+++ b/src/lib/relay-strikes.ts
@@ -174,7 +174,8 @@ class RelaySessionStrikes {
     if (now < e.rateLimitUntil && !this.cacheRelayKeys.has(key)) return
 
     if (!this.cacheRelayKeys.has(key)) {
-      if (now - e.readLastStrikeIncrementAt < STRIKE_INCREMENT_DEBOUNCE_MS) return
+      // HTTP index failures often arrive in parallel; count each so session skip engages quickly.
+      if (_source !== 'http' && now - e.readLastStrikeIncrementAt < STRIKE_INCREMENT_DEBOUNCE_MS) return
       e.readLastStrikeIncrementAt = now
     }
 
diff --git a/src/services/client-query.service.ts b/src/services/client-query.service.ts
index 184421e3..1be77363 100644
--- a/src/services/client-query.service.ts
+++ b/src/services/client-query.service.ts
@@ -475,7 +475,7 @@ export class QueryService {
         urls
           .filter((u) => isHttpRelayUrl(u))
           .map((u) => normalizeHttpRelayUrl(u) || u)
-          .filter(Boolean)
+          .filter((u): u is string => Boolean(u) && !relaySessionStrikes.isReadHttpSkipped(u))
       )
     )
     const wsQueryUrls = urls.filter((u) => !isHttpRelayUrl(u))