From 8e6ace2fe2db7aa3bd4fb09eae5ca8d8c26f112a Mon Sep 17 00:00:00 2001
From: Tyler <26290074+tylersayshi@users.noreply.github.com>
Date: Wed, 3 Jun 2026 15:16:48 -0700
Subject: [PATCH] fix: derive lexicon DNS authority from all-but-last NSID
 segment

Permission-set expansion resolved the lexicon's DNS authority using a
fixed `parts[..2]`, which only works for three-segment NSIDs. For a
four-segment NSID such as community.lexicon.bookmarks.authManageBookmarks
this dropped a segment and queried _lexicon.lexicon.community instead of
_lexicon.bookmarks.lexicon.community, failing with "DNS resolution
failed: ... no record found".

The authority is every NSID segment except the last (the name),
reversed. Use parts[..parts.len() - 1] to match the spec and the
existing extract_namespace_authority helper, and update the DNS
authority test with three/four-segment and bookmarks regression cases.
---
 crates/tranquil-scopes/src/permission_set.rs | 37 +++++++++-----------
 1 file changed, 17 insertions(+), 20 deletions(-)

diff --git a/crates/tranquil-scopes/src/permission_set.rs b/crates/tranquil-scopes/src/permission_set.rs
index 4c99c56..6f981d9 100644
--- a/crates/tranquil-scopes/src/permission_set.rs
+++ b/crates/tranquil-scopes/src/permission_set.rs
@@ -171,7 +171,7 @@ async fn fetch_lexicon_via_atproto(nsid: &str) -> Result<LexiconDoc, ScopeExpans
         return Err(ScopeExpansionError::InvalidNsid(nsid.to_string()));
     }
 
-    let authority = parts[..2]
+    let authority = parts[..parts.len() - 1]
         .iter()
         .rev()
         .cloned()
@@ -661,26 +661,23 @@ mod tests {
         }
     }
 
+    fn dns_authority(nsid: &str) -> String {
+        let parts: Vec<&str> = nsid.split('.').collect();
+        parts[..parts.len() - 1]
+            .iter()
+            .rev()
+            .cloned()
+            .collect::<Vec<_>>()
+            .join(".")
+    }
+
     #[test]
     fn test_nsid_authority_extraction_for_dns() {
-        let nsid = "io.atcr.authFullApp";
-        let parts: Vec<&str> = nsid.split('.').collect();
-        let authority = parts[..2]
-            .iter()
-            .rev()
-            .cloned()
-            .collect::<Vec<_>>()
-            .join(".");
-        assert_eq!(authority, "atcr.io");
-
-        let nsid2 = "app.bsky.feed.post";
-        let parts2: Vec<&str> = nsid2.split('.').collect();
-        let authority2 = parts2[..2]
-            .iter()
-            .rev()
-            .cloned()
-            .collect::<Vec<_>>()
-            .join(".");
-        assert_eq!(authority2, "bsky.app");
+        assert_eq!(dns_authority("io.atcr.authFullApp"), "atcr.io");
+        assert_eq!(dns_authority("app.bsky.feed.post"), "feed.bsky.app");
+        assert_eq!(
+            dns_authority("community.lexicon.bookmarks.authManageBookmarks"),
+            "bookmarks.lexicon.community"
+        );
     }
 }