diff --git a/app/Jobs/RefreshSocialToken.php b/app/Jobs/RefreshSocialToken.php
index 86957f2d..25b6b1bf 100644
--- a/app/Jobs/RefreshSocialToken.php
+++ b/app/Jobs/RefreshSocialToken.php
@@ -26,20 +26,12 @@ public function handle(ConnectionVerifier $verifier): void
         try {
             $verifier->refreshToken($this->account);
         } catch (PlatformUnavailableException $e) {
-            // Platform is down (5xx / network). Leave the account alone —
-            // next scheduled run will try again. Critically, do NOT mark
-            // the account expired: that would trigger a false-positive
-            // "reconnect your account" notification.
             Log::warning('Token refresh skipped: platform unavailable', [
                 'account_id' => $this->account->id,
                 'platform' => $this->account->platform->value,
                 'error' => $e->getMessage(),
             ]);
         } catch (TokenExpiredException $e) {
-            // refresh_token rejected by the provider (revoked / rotated /
-            // expired beyond refresh). Mark the account so the user is
-            // notified immediately instead of waiting for the next failed
-            // publish or the daily verify pass.
             $this->account->markAsTokenExpired($e->getMessage());
         } catch (Throwable $e) {
             Log::warning('Proactive token refresh failed', [
diff --git a/app/Jobs/VerifyWorkspaceConnections.php b/app/Jobs/VerifyWorkspaceConnections.php
index 5174b13d..6d01c957 100644
--- a/app/Jobs/VerifyWorkspaceConnections.php
+++ b/app/Jobs/VerifyWorkspaceConnections.php
@@ -66,8 +66,6 @@ private function verifyAccount(ConnectionVerifier $verifier, SocialAccount $acco
 
             return true;
         } catch (PlatformUnavailableException $e) {
-            // Platform is down (5xx / network). The account's token is not
-            // provably bad — skip silently and try again next pass.
             Log::warning('Social account verification skipped: platform unavailable', [
                 'account_id' => $account->id,
                 'platform' => $account->platform->value,
diff --git a/app/Services/Social/ConnectionVerifier.php b/app/Services/Social/ConnectionVerifier.php
index e5c9fc17..d13bb620 100644
--- a/app/Services/Social/ConnectionVerifier.php
+++ b/app/Services/Social/ConnectionVerifier.php
@@ -28,9 +28,6 @@ public function verify(SocialAccount $account): bool
         // LinkedIn, etc.) invalidate the previous refresh_token on each
         // refresh, so proactive refreshes during races cause false-positive
         // disconnects even though the access_token still works fine.
-        //
-        // PlatformUnavailableException from refresh propagates naturally so
-        // the caller can distinguish "platform is down" from "token bad".
         if ($account->is_token_expired) {
             $this->refreshToken($account);
 
@@ -76,9 +73,10 @@ private function callVerifyEndpoint(SocialAccount $account): bool
      * Refresh the account's token via the platform-specific OAuth flow.
      * Callers that want the smart "try access_token first" behavior should
      * use verify() instead. This method always attempts a refresh under
-     * the per-account lock and throws TokenExpiredException on failure.
+     * the per-account lock.
      *
-     * @throws TokenExpiredException if refresh fails
+     * @throws TokenExpiredException if refresh is rejected by the provider (4xx)
+     * @throws PlatformUnavailableException if the platform is unreachable (5xx / network)
      */
     public function refreshToken(SocialAccount $account): void
     {
@@ -168,9 +166,6 @@ private function refreshBlueskyToken(SocialAccount $account): void
         $service = $account->meta['service'] ?? config('trypost.platforms.bluesky.default_service');
         $client = TokenRefreshClient::for(Platform::Bluesky);
 
-        // Try refresh token first. Connection errors / 5xx surface as
-        // PlatformUnavailableException (Bluesky is down — don't touch the
-        // account's status). 4xx falls through to the re-auth fallback.
         try {
             $response = $client->send(fn () => Http::withToken($account->refresh_token)
                 ->post("{$service}/xrpc/com.atproto.server.refreshSession"));
@@ -512,7 +507,7 @@ private function verifyBluesky(SocialAccount $account): bool
 
     private function verifyMastodon(SocialAccount $account): bool
     {
-        $instance = $account->meta['instance'] ?? 'https://mastodon.social';
+        $instance = $account->meta['instance'] ?? config('trypost.platforms.mastodon.default_instance');
 
         $response = Http::withToken($account->access_token)
             ->get("{$instance}/api/v1/accounts/verify_credentials");
diff --git a/config/trypost.php b/config/trypost.php
index 29fcfb95..45f1d93d 100644
--- a/config/trypost.php
+++ b/config/trypost.php
@@ -116,6 +116,8 @@
         ],
         'mastodon' => [
             'enabled' => env('MASTODON_ENABLED', true),
+            // Default instance used when the account has no `meta.instance` override.
+            'default_instance' => env('MASTODON_DEFAULT_INSTANCE', 'https://mastodon.social'),
         ],
     ],
 
diff --git a/tests/Feature/Jobs/RefreshSocialTokenTest.php b/tests/Feature/Jobs/RefreshSocialTokenTest.php
index 172076a7..c9a9226d 100644
--- a/tests/Feature/Jobs/RefreshSocialTokenTest.php
+++ b/tests/Feature/Jobs/RefreshSocialTokenTest.php
@@ -86,7 +86,6 @@
 
     (new RefreshSocialToken($this->account))->handle($verifier);
 
-    // Critically: account status stays Connected, no notification dispatched.
     expect($this->account->fresh()->status)->toBe(Status::Connected);
     Queue::assertNotPushed(SendNotification::class);
 });
diff --git a/tests/Feature/Services/Social/ConnectionVerifierTest.php b/tests/Feature/Services/Social/ConnectionVerifierTest.php
index 9d025385..8488a972 100644
--- a/tests/Feature/Services/Social/ConnectionVerifierTest.php
+++ b/tests/Feature/Services/Social/ConnectionVerifierTest.php
@@ -411,7 +411,6 @@
 
 test('bluesky 5xx during refresh raises PlatformUnavailable even when password fallback is stored', function () {
     Http::fake([
-        // Both endpoints return 5xx — the platform is genuinely down.
         'bsky.social/xrpc/com.atproto.server.refreshSession' => Http::response('upstream timeout', 503),
         'bsky.social/xrpc/com.atproto.server.createSession' => Http::response('upstream timeout', 503),
     ]);
diff --git a/tests/Feature/VerifyWorkspaceConnectionsTest.php b/tests/Feature/VerifyWorkspaceConnectionsTest.php
index 5eaff679..19976701 100644
--- a/tests/Feature/VerifyWorkspaceConnectionsTest.php
+++ b/tests/Feature/VerifyWorkspaceConnectionsTest.php
@@ -137,7 +137,6 @@
 
     VerifyWorkspaceConnections::dispatch($workspace);
 
-    // Status untouched, no notification email.
     expect($account->fresh()->status)->toBe(Status::Connected);
     Mail::assertNothingQueued();
 });