diff --git a/src/lib/helpers/apiEndpoint.test.ts b/src/lib/helpers/apiEndpoint.test.ts
new file mode 100644
index 0000000000..cfd8fd296d
--- /dev/null
+++ b/src/lib/helpers/apiEndpoint.test.ts
@@ -0,0 +1,83 @@
+import { describe, expect, it } from 'vitest';
+import {
+    buildRegionalV1Endpoint,
+    getRegionSubdomain,
+    stripLeadingRegionSubdomain
+} from '$lib/helpers/apiEndpoint';
+
+describe('getRegionSubdomain', () => {
+    it('maps the well-known regions to their subdomains', () => {
+        expect(getRegionSubdomain('fra')).toBe('fra.');
+        expect(getRegionSubdomain('syd')).toBe('syd.');
+        expect(getRegionSubdomain('nyc')).toBe('nyc.');
+        expect(getRegionSubdomain('sfo')).toBe('sfo.');
+        expect(getRegionSubdomain('sgp')).toBe('sgp.');
+        expect(getRegionSubdomain('tor')).toBe('tor.');
+    });
+
+    it('derives a subdomain for regions that are not hardcoded', () => {
+        // A project living in a newer Appwrite Cloud region (e.g. Bangalore)
+        // must still be routed to its own regional subdomain. Previously these
+        // fell through to the empty default, so the SDK hit the apex domain and
+        // navigation got stuck with CORS errors.
+        expect(getRegionSubdomain('blr')).toBe('blr.');
+        expect(getRegionSubdomain('lon')).toBe('lon.');
+    });
+
+    it('resolves the default placeholder and empty values to the apex domain', () => {
+        expect(getRegionSubdomain('default')).toBe('');
+        expect(getRegionSubdomain('')).toBe('');
+        expect(getRegionSubdomain(undefined)).toBe('');
+    });
+});
+
+describe('buildRegionalV1Endpoint', () => {
+    it('leaves the host untouched when multi-region is disabled', () => {
+        expect(buildRegionalV1Endpoint('https:', 'cloud.appwrite.io', 'blr', false)).toBe(
+            'https://cloud.appwrite.io/v1'
+        );
+    });
+
+    it('leaves the host untouched for the default/unknown placeholder region', () => {
+        expect(buildRegionalV1Endpoint('https:', 'fra.cloud.appwrite.io', 'default', true)).toBe(
+            'https://fra.cloud.appwrite.io/v1'
+        );
+    });
+
+    it('prepends the regional subdomain for a hardcoded region', () => {
+        expect(buildRegionalV1Endpoint('https:', 'fra.cloud.appwrite.io', 'nyc', true)).toBe(
+            'https://nyc.cloud.appwrite.io/v1'
+        );
+    });
+
+    it('prepends the regional subdomain for a region outside the hardcoded set', () => {
+        // apex host
+        expect(buildRegionalV1Endpoint('https:', 'cloud.appwrite.io', 'blr', true)).toBe(
+            'https://blr.cloud.appwrite.io/v1'
+        );
+        // host that already carries a known region label
+        expect(buildRegionalV1Endpoint('https:', 'fra.cloud.appwrite.io', 'blr', true)).toBe(
+            'https://blr.cloud.appwrite.io/v1'
+        );
+    });
+
+    it('does not double the subdomain when the host already carries the target region', () => {
+        expect(buildRegionalV1Endpoint('https:', 'blr.cloud.appwrite.io', 'blr', true)).toBe(
+            'https://blr.cloud.appwrite.io/v1'
+        );
+    });
+});
+
+describe('stripLeadingRegionSubdomain', () => {
+    it('strips a known leading region label', () => {
+        expect(stripLeadingRegionSubdomain('fra.cloud.appwrite.io')).toBe('cloud.appwrite.io');
+    });
+
+    it('collapses doubled region labels', () => {
+        expect(stripLeadingRegionSubdomain('fra.fra.cloud.appwrite.io')).toBe('cloud.appwrite.io');
+    });
+
+    it('leaves a bare apex host untouched', () => {
+        expect(stripLeadingRegionSubdomain('cloud.appwrite.io')).toBe('cloud.appwrite.io');
+    });
+});
diff --git a/src/lib/helpers/apiEndpoint.ts b/src/lib/helpers/apiEndpoint.ts
index 1bcc1bf3bd..8de18c7e28 100644
--- a/src/lib/helpers/apiEndpoint.ts
+++ b/src/lib/helpers/apiEndpoint.ts
@@ -1,10 +1,4 @@
 import {
-    REGION_FRA,
-    REGION_NYC,
-    REGION_SFO,
-    REGION_SGP,
-    REGION_SYD,
-    REGION_TOR,
     SUBDOMAIN_FRA,
     SUBDOMAIN_NYC,
     SUBDOMAIN_SFO,
@@ -13,6 +7,12 @@ import {
     SUBDOMAIN_TOR
 } from '$lib/constants';
 
+/**
+ * The placeholder region used for region-less projects. It maps to the apex
+ * domain (no subdomain) and must never be turned into a subdomain.
+ */
+const DEFAULT_REGION = 'default';
+
 /** Ordered list of region DNS prefixes (e.g. `fra.`) for stripping from API hostnames. */
 const REGION_SUBDOMAIN_PREFIXES: readonly string[] = [
     SUBDOMAIN_FRA,
@@ -26,14 +26,21 @@ const REGION_SUBDOMAIN_PREFIXES: readonly string[] = [
 /**
  * Removes leading Appwrite Cloud region label(s) from `hostname` (e.g. `fra.`).
  * Strips repeatedly so a doubled prefix (`fra.fra.cloud...`) does not become
- * `nyc.fra.cloud...` after prepending another region.
+ * `nyc.fra.cloud...` after prepending another region. An optional `extraPrefix`
+ * (the region about to be prepended) is stripped too, so regions outside the
+ * well-known set do not get doubled up.
  */
-export function stripLeadingRegionSubdomain(hostname: string): string {
+export function stripLeadingRegionSubdomain(hostname: string, extraPrefix?: string): string {
+    const prefixes =
+        extraPrefix && !REGION_SUBDOMAIN_PREFIXES.includes(extraPrefix)
+            ? [extraPrefix, ...REGION_SUBDOMAIN_PREFIXES]
+            : REGION_SUBDOMAIN_PREFIXES;
+
     let host = hostname;
     let changed = true;
     while (changed) {
         changed = false;
-        for (const prefix of REGION_SUBDOMAIN_PREFIXES) {
+        for (const prefix of prefixes) {
             if (host.startsWith(prefix)) {
                 host = host.slice(prefix.length);
                 changed = true;
@@ -44,24 +51,17 @@ export function stripLeadingRegionSubdomain(hostname: string): string {
     return host;
 }
 
-/** Region prefix (e.g. `fra.`) used before the API hostname when multi-region is enabled. */
+/**
+ * Region prefix (e.g. `fra.`) used before the API hostname when multi-region is
+ * enabled. The set of Appwrite Cloud regions is dynamic and grows over time, so
+ * the prefix is derived directly from the region id rather than a hardcoded
+ * list — otherwise projects in a newly added region resolve to no subdomain,
+ * hit the apex domain, and fail with CORS errors. The `default` placeholder
+ * (and empty/undefined values) resolve to the apex domain.
+ */
 export function getRegionSubdomain(region?: string): string {
-    switch (region) {
-        case REGION_FRA:
-            return SUBDOMAIN_FRA;
-        case REGION_SYD:
-            return SUBDOMAIN_SYD;
-        case REGION_NYC:
-            return SUBDOMAIN_NYC;
-        case REGION_SFO:
-            return SUBDOMAIN_SFO;
-        case REGION_SGP:
-            return SUBDOMAIN_SGP;
-        case REGION_TOR:
-            return SUBDOMAIN_TOR;
-        default:
-            return '';
-    }
+    if (!region || region === DEFAULT_REGION) return '';
+    return `${region}.`;
 }
 
 /**
@@ -85,6 +85,6 @@ export function buildRegionalV1Endpoint(
         return `${protocol}//${hostname}/v1`;
     }
 
-    const hostWithoutRegion = stripLeadingRegionSubdomain(hostname);
+    const hostWithoutRegion = stripLeadingRegionSubdomain(hostname, subdomain);
     return `${protocol}//${subdomain}${hostWithoutRegion}/v1`;
 }