fix: make access tokens non-expiring (matching Mastodon behavior)

Access tokens were expiring after 1 hour, causing Phanpy/Elk/Moshidon
to get 401 errors and become unusable. Mastodon itself creates
non-expiring access tokens (valid until revoked).

Removed expiresAt from all three grant types (authorization_code,
client_credentials, refresh_token). Refresh tokens keep their 90-day
expiry as a safety measure. Removed expires_in from JSON responses.

lib/mastodon/routes/oauth.js

@@ -467,7 +467,6 @@ router.post("/oauth/token", async (req, res, next) => {
         accessToken,
         createdAt: new Date(),
         grantType: "client_credentials",
-        expiresAt: new Date(Date.now() + 3600 * 1000),
       });
 
       return res.json({
@@ -475,7 +474,6 @@ router.post("/oauth/token", async (req, res, next) => {
         token_type: "Bearer",
         scope: "read",
         created_at: Math.floor(Date.now() / 1000),
-        expires_in: 3600,
       });
     }
 
@@ -510,9 +508,9 @@ router.post("/oauth/token", async (req, res, next) => {
           $set: {
             accessToken: newAccessToken,
             refreshToken: newRefreshToken,
-            expiresAt: new Date(Date.now() + 3600 * 1000),
             refreshExpiresAt: new Date(Date.now() + 90 * 24 * 3600 * 1000),
           },
+          $unset: { expiresAt: "" },
         },
       );
 
@@ -522,7 +520,6 @@ router.post("/oauth/token", async (req, res, next) => {
         scope: existing.scopes.join(" "),
         created_at: Math.floor(existing.createdAt.getTime() / 1000),
         refresh_token: newRefreshToken,
-        expires_in: 3600,
       });
     }
 
@@ -590,8 +587,9 @@ router.post("/oauth/token", async (req, res, next) => {
       }
     }
 
-    // Generate access token and refresh token with expiry.
-    const ACCESS_TOKEN_TTL = 3600 * 1000; // 1 hour
+    // Generate access token and refresh token.
+    // Access tokens do not expire (matching Mastodon behavior — valid until revoked).
+    // Refresh tokens expire after 90 days as a safety measure.
     const REFRESH_TOKEN_TTL = 90 * 24 * 3600 * 1000; // 90 days
     const accessToken = randomHex(64);
     const refreshToken = randomHex(64);
@@ -601,7 +599,6 @@ router.post("/oauth/token", async (req, res, next) => {
         $set: {
           accessToken,
           refreshToken,
-          expiresAt: new Date(Date.now() + ACCESS_TOKEN_TTL),
           refreshExpiresAt: new Date(Date.now() + REFRESH_TOKEN_TTL),
         },
       },
@@ -613,7 +610,6 @@ router.post("/oauth/token", async (req, res, next) => {
       scope: grant.scopes.join(" "),
       created_at: Math.floor(grant.createdAt.getTime() / 1000),
       refresh_token: refreshToken,
-      expires_in: 3600,
     });
   } catch (error) {
     next(error);

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@rmdes/indiekit-endpoint-activitypub",
-  "version": "3.12.3",
+  "version": "3.12.4",
   "description": "ActivityPub federation endpoint for Indiekit via Fedify. Adds full fediverse support: actor, inbox, outbox, followers, following, syndication, and Mastodon migration.",
   "keywords": [
     "indiekit",