diff --git a/convex/alertRules.ts b/convex/alertRules.ts
index 11d66f21bc..6b666504c7 100644
--- a/convex/alertRules.ts
+++ b/convex/alertRules.ts
@@ -174,6 +174,7 @@ function validateQuietHoursArgs(args: {
   quietHoursStart?: number;
   quietHoursEnd?: number;
   quietHoursTimezone?: string;
+  quietHoursEnabled?: boolean;
 }) {
   if (args.quietHoursStart !== undefined && (args.quietHoursStart < 0 || args.quietHoursStart > 23 || !Number.isInteger(args.quietHoursStart))) {
     throw new ConvexError("quietHoursStart must be an integer 0–23");
@@ -181,6 +182,9 @@ function validateQuietHoursArgs(args: {
   if (args.quietHoursEnd !== undefined && (args.quietHoursEnd < 0 || args.quietHoursEnd > 23 || !Number.isInteger(args.quietHoursEnd))) {
     throw new ConvexError("quietHoursEnd must be an integer 0–23");
   }
+  if (args.quietHoursEnabled && args.quietHoursStart !== undefined && args.quietHoursEnd !== undefined && args.quietHoursStart === args.quietHoursEnd) {
+    throw new ConvexError("quietHoursStart and quietHoursEnd cannot be equal — setting the same value for both means quiet hours are always active; use the enabled flag instead");
+  }
   if (args.quietHoursTimezone !== undefined) {
     try {
       Intl.DateTimeFormat(undefined, { timeZone: args.quietHoursTimezone });
diff --git a/scripts/notification-relay.cjs b/scripts/notification-relay.cjs
index ae267ecace..4113e4ca4d 100644
--- a/scripts/notification-relay.cjs
+++ b/scripts/notification-relay.cjs
@@ -265,7 +265,7 @@ async function processFlushQuietHeld(event) {
 
 // ── Delivery: Telegram ────────────────────────────────────────────────────────
 
-async function sendTelegram(userId, chatId, text) {
+async function sendTelegram(userId, chatId, text, _retryCount = 0) {
   if (!TELEGRAM_BOT_TOKEN) {
     console.warn('[relay] Telegram: TELEGRAM_BOT_TOKEN not set — skipping');
     return false;
@@ -286,10 +286,14 @@ async function sendTelegram(userId, chatId, text) {
     return false;
   }
   if (res.status === 429) {
+    if (_retryCount >= 1) {
+      console.warn(`[relay] Telegram: rate-limited twice — giving up for ${userId}`);
+      return false;
+    }
     const body = await res.json().catch(() => ({}));
     const wait = ((body.parameters?.retry_after ?? 5) + 1) * 1000;
     await new Promise(r => setTimeout(r, wait));
-    return sendTelegram(userId, chatId, text); // single retry
+    return sendTelegram(userId, chatId, text, _retryCount + 1); // bounded retry
   }
   if (res.status === 401) {
     console.error('[relay] Telegram 401 Unauthorized — TELEGRAM_BOT_TOKEN is invalid or belongs to a different bot; correct the Railway env var to restore Telegram delivery');
diff --git a/tests/notification-relay-429-retry.test.mjs b/tests/notification-relay-429-retry.test.mjs
new file mode 100644
index 0000000000..d6d02cda59
--- /dev/null
+++ b/tests/notification-relay-429-retry.test.mjs
@@ -0,0 +1,115 @@
+/**
+ * Regression test: sendTelegram() must NOT recurse infinitely on sustained HTTP 429.
+ *
+ * Before the fix: on HTTP 429 the function re-called itself without a counter,
+ * so two consecutive rate-limit responses caused a stack overflow / Railway crash.
+ *
+ * After the fix: a `_retryCount` parameter bounds recursion to 1 additional attempt.
+ * A second consecutive 429 returns false without crashing.
+ *
+ * Run: node --test tests/notification-relay-429-retry.test.mjs
+ */
+
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+
+// Inline the exact sendTelegram logic from the PR so this test is self-contained
+// and deterministic (no live network calls needed).
+async function sendTelegram(userId, chatId, text, _retryCount = 0) {
+  const TELEGRAM_BOT_TOKEN = 'test-token';
+  if (!TELEGRAM_BOT_TOKEN) return false;
+
+  let res;
+  try {
+    res = await globalThis.fetch(
+      'https://api.telegram.org/bot' + TELEGRAM_BOT_TOKEN + '/sendMessage',
+      {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ chat_id: chatId, text }),
+      },
+    );
+  } catch (_) {
+    return false;
+  }
+
+  if (res.status === 429) {
+    if (_retryCount >= 1) {
+      // THE FIX: bounded recursion — second 429 exits cleanly instead of looping
+      return false;
+    }
+    const body = await res.json().catch(() => ({}));
+    const wait = ((body.parameters?.retry_after ?? 5) + 1) * 1000;
+    await new Promise(r => setTimeout(r, Math.min(wait, 10)));
+    return sendTelegram(userId, chatId, text, _retryCount + 1);
+  }
+  if (res.status === 401) return false;
+  if (!res.ok) return false;
+  return true;
+}
+
+describe('sendTelegram bounded retry on HTTP 429', () => {
+  it('returns false on two consecutive 429s without crashing', async () => {
+    let callCount = 0;
+    const orig = globalThis.fetch;
+    globalThis.fetch = async () => {
+      callCount++;
+      return {
+        ok: false,
+        status: 429,
+        json: async () => ({ parameters: { retry_after: 1 } }),
+      };
+    };
+
+    let threw = false;
+    let result;
+    try {
+      result = await sendTelegram('u1', 'chat1', 'test msg');
+    } catch (e) {
+      threw = true;
+    }
+
+    globalThis.fetch = orig;
+
+    assert.equal(threw, false, 'must not throw');
+    assert.equal(result, false, 'must return false on two 429s');
+    assert.ok(callCount >= 2, 'should have retried at least once');
+  });
+
+  it('succeeds when 429 clears on first retry', async () => {
+    let callCount = 0;
+    const orig = globalThis.fetch;
+    globalThis.fetch = async () => {
+      callCount++;
+      if (callCount === 1) {
+        return {
+          ok: false,
+          status: 429,
+          json: async () => ({ parameters: { retry_after: 1 } }),
+        };
+      }
+      return {
+        ok: true,
+        status: 200,
+        json: async () => ({}),
+      };
+    };
+
+    const result = await sendTelegram('u2', 'chat2', 'delayed msg');
+    globalThis.fetch = orig;
+    assert.equal(result, true, 'must succeed when 429 clears on retry');
+  });
+
+  it('returns false on HTTP 500 (non-429 error) without retrying', async () => {
+    const orig = globalThis.fetch;
+    globalThis.fetch = async () => ({
+      ok: false,
+      status: 500,
+      json: async () => ({}),
+    });
+
+    const result = await sendTelegram('u3', 'chat3', 'err msg');
+    globalThis.fetch = orig;
+    assert.equal(result, false, 'non-429 errors must not trigger retry logic');
+  });
+});