diff --git a/crates/adapters/activitypub-base/src/service.rs b/crates/adapters/activitypub-base/src/service.rs
index 52ec70a..8d07d3e 100644
--- a/crates/adapters/activitypub-base/src/service.rs
+++ b/crates/adapters/activitypub-base/src/service.rs
@@ -74,6 +74,7 @@ fn thought_note_json(
     thought: &domain::models::thought::Thought,
     local_actor: &crate::actors::DbActor,
     base_url: &str,
+    in_reply_to_url: Option<&str>,
 ) -> anyhow::Result<(url::Url, serde_json::Value)> {
     let ap_id = url::Url::parse(&format!("{}/thoughts/{}", base_url, thought.id))?;
 
@@ -107,7 +108,7 @@ fn thought_note_json(
     if let Some(ref cw) = thought.content_warning {
         note["summary"] = serde_json::json!(cw);
     }
-    if let Some(ref reply_url) = thought.in_reply_to_url {
+    if let Some(reply_url) = in_reply_to_url {
         note["inReplyTo"] = serde_json::json!(reply_url);
     }
     if let Some(updated_at) = thought.updated_at {
@@ -1415,6 +1416,7 @@ impl domain::ports::OutboundFederationPort for ActivityPubService {
         author_user_id: &domain::value_objects::UserId,
         thought: &domain::models::thought::Thought,
         _author_username: &str,
+        in_reply_to_url: Option<&str>,
     ) -> Result<(), domain::errors::DomainError> {
         let user_uuid = author_user_id.as_uuid();
         let data = self.federation_config.to_request_data();
@@ -1426,8 +1428,9 @@ impl domain::ports::OutboundFederationPort for ActivityPubService {
             return Ok(());
         };
 
-        let (ap_id, note) = thought_note_json(thought, &local_actor, &self.base_url)
-            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))?;
+        let (ap_id, note) =
+            thought_note_json(thought, &local_actor, &self.base_url, in_reply_to_url)
+                .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))?;
 
         let create = crate::activities::CreateActivity {
             id: ap_id,
@@ -1476,6 +1479,7 @@ impl domain::ports::OutboundFederationPort for ActivityPubService {
         author_user_id: &domain::value_objects::UserId,
         thought: &domain::models::thought::Thought,
         _author_username: &str,
+        in_reply_to_url: Option<&str>,
     ) -> Result<(), domain::errors::DomainError> {
         let user_uuid = author_user_id.as_uuid();
         let data = self.federation_config.to_request_data();
@@ -1487,8 +1491,9 @@ impl domain::ports::OutboundFederationPort for ActivityPubService {
             return Ok(());
         };
 
-        let (_ap_id, note) = thought_note_json(thought, &local_actor, &self.base_url)
-            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))?;
+        let (_ap_id, note) =
+            thought_note_json(thought, &local_actor, &self.base_url, in_reply_to_url)
+                .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))?;
 
         let update_id = url::Url::parse(&format!(
             "{}/activities/update/{}",
diff --git a/crates/adapters/postgres-search/src/lib.rs b/crates/adapters/postgres-search/src/lib.rs
index dd67998..0faec17 100644
--- a/crates/adapters/postgres-search/src/lib.rs
+++ b/crates/adapters/postgres-search/src/lib.rs
@@ -29,8 +29,6 @@ struct FeedRow {
     t_user_id: uuid::Uuid,
     content: String,
     in_reply_to_id: Option<uuid::Uuid>,
-    in_reply_to_url: Option<String>,
-    t_ap_id: Option<String>,
     visibility: String,
     content_warning: Option<String>,
     sensitive: bool,
@@ -47,8 +45,6 @@ struct FeedRow {
     header_url: Option<String>,
     custom_css: Option<String>,
     author_local: bool,
-    u_ap_id: Option<String>,
-    inbox_url: Option<String>,
     author_created_at: DateTime<Utc>,
     author_updated_at: DateTime<Utc>,
     like_count: i64,
@@ -59,12 +55,12 @@ struct FeedRow {
 const FEED_SELECT: &str = "
     SELECT
         t.id AS thought_id, t.user_id AS t_user_id, t.content,
-        t.in_reply_to_id, t.in_reply_to_url, t.ap_id AS t_ap_id,
+        t.in_reply_to_id,
         t.visibility, t.content_warning, t.sensitive, t.local AS t_local,
         t.created_at AS thought_created_at, t.updated_at,
         u.id AS author_id, u.username, u.email, u.password_hash,
         u.display_name, u.bio, u.avatar_url, u.header_url, u.custom_css,
-        u.local AS author_local, u.ap_id AS u_ap_id, u.inbox_url,
+        u.local AS author_local,
         u.created_at AS author_created_at, u.updated_at AS author_updated_at,
         (SELECT COUNT(*) FROM likes l WHERE l.thought_id=t.id) AS like_count,
         (SELECT COUNT(*) FROM boosts b WHERE b.thought_id=t.id) AS boost_count,
@@ -77,8 +73,6 @@ fn row_to_entry(r: FeedRow) -> FeedEntry {
         user_id: UserId::from_uuid(r.t_user_id),
         content: Content::new_remote(r.content),
         in_reply_to_id: r.in_reply_to_id.map(ThoughtId::from_uuid),
-        in_reply_to_url: r.in_reply_to_url,
-        ap_id: r.t_ap_id,
         visibility: Visibility::from_db_str(&r.visibility),
         content_warning: r.content_warning,
         sensitive: r.sensitive,
@@ -97,8 +91,6 @@ fn row_to_entry(r: FeedRow) -> FeedEntry {
         header_url: r.header_url,
         custom_css: r.custom_css,
         local: r.author_local,
-        ap_id: r.u_ap_id,
-        inbox_url: r.inbox_url,
         created_at: r.author_created_at,
         updated_at: r.author_updated_at,
     };
diff --git a/crates/adapters/postgres/src/activitypub.rs b/crates/adapters/postgres/src/activitypub.rs
index b51a184..2276ee4 100644
--- a/crates/adapters/postgres/src/activitypub.rs
+++ b/crates/adapters/postgres/src/activitypub.rs
@@ -60,8 +60,6 @@ impl ActivityPubRepository for PgActivityPubRepository {
                         user_id: UserId::from_uuid(r.user_id),
                         content: Content::new_remote(r.content),
                         in_reply_to_id: r.in_reply_to_id.map(ThoughtId::from_uuid),
-                        in_reply_to_url: None,
-                        ap_id: None,
                         visibility: Visibility::Public,
                         content_warning: r.content_warning,
                         sensitive: r.sensitive,
@@ -127,8 +125,6 @@ impl ActivityPubRepository for PgActivityPubRepository {
                     user_id: UserId::from_uuid(r.user_id),
                     content: Content::new_remote(r.content),
                     in_reply_to_id: r.in_reply_to_id.map(ThoughtId::from_uuid),
-                    in_reply_to_url: None,
-                    ap_id: None,
                     visibility: Visibility::Public,
                     content_warning: r.content_warning,
                     sensitive: r.sensitive,
diff --git a/crates/adapters/postgres/src/feed.rs b/crates/adapters/postgres/src/feed.rs
index 14c0f0d..9519194 100644
--- a/crates/adapters/postgres/src/feed.rs
+++ b/crates/adapters/postgres/src/feed.rs
@@ -29,8 +29,6 @@ struct FeedRow {
     t_user_id: uuid::Uuid,
     content: String,
     in_reply_to_id: Option<uuid::Uuid>,
-    in_reply_to_url: Option<String>,
-    t_ap_id: Option<String>,
     visibility: String,
     content_warning: Option<String>,
     sensitive: bool,
@@ -47,8 +45,6 @@ struct FeedRow {
     header_url: Option<String>,
     custom_css: Option<String>,
     author_local: bool,
-    u_ap_id: Option<String>,
-    inbox_url: Option<String>,
     author_created_at: DateTime<Utc>,
     author_updated_at: DateTime<Utc>,
     like_count: i64,
@@ -83,7 +79,7 @@ fn feed_select(viewer: Option<uuid::Uuid>) -> String {
         "
     SELECT
         t.id AS thought_id, t.user_id AS t_user_id, t.content,
-        t.in_reply_to_id, t.in_reply_to_url, t.ap_id AS t_ap_id,
+        t.in_reply_to_id,
         t.visibility, t.content_warning, t.sensitive, t.local AS t_local,
         t.created_at AS thought_created_at, t.updated_at,
         u.id AS author_id,
@@ -98,7 +94,7 @@ fn feed_select(viewer: Option<uuid::Uuid>) -> String {
         u.bio,
         COALESCE(ra.avatar_url, u.avatar_url) AS avatar_url,
         u.header_url, u.custom_css,
-        u.local AS author_local, u.ap_id AS u_ap_id, u.inbox_url,
+        u.local AS author_local,
         u.created_at AS author_created_at, u.updated_at AS author_updated_at,
         (SELECT COUNT(*) FROM likes l WHERE l.thought_id=t.id) AS like_count,
         (SELECT COUNT(*) FROM boosts b WHERE b.thought_id=t.id) AS boost_count,
@@ -116,8 +112,6 @@ fn row_to_entry(r: FeedRow) -> FeedEntry {
         user_id: UserId::from_uuid(r.t_user_id),
         content: Content::new_remote(r.content),
         in_reply_to_id: r.in_reply_to_id.map(ThoughtId::from_uuid),
-        in_reply_to_url: r.in_reply_to_url,
-        ap_id: r.t_ap_id,
         visibility: Visibility::from_db_str(&r.visibility),
         content_warning: r.content_warning,
         sensitive: r.sensitive,
@@ -136,8 +130,6 @@ fn row_to_entry(r: FeedRow) -> FeedEntry {
         header_url: r.header_url,
         custom_css: r.custom_css,
         local: r.author_local,
-        ap_id: r.u_ap_id,
-        inbox_url: r.inbox_url,
         created_at: r.author_created_at,
         updated_at: r.author_updated_at,
     };
diff --git a/crates/adapters/postgres/src/thought.rs b/crates/adapters/postgres/src/thought.rs
index ed193d8..be78c7b 100644
--- a/crates/adapters/postgres/src/thought.rs
+++ b/crates/adapters/postgres/src/thought.rs
@@ -28,8 +28,6 @@ pub(crate) struct ThoughtRow {
     pub user_id: uuid::Uuid,
     pub content: String,
     pub in_reply_to_id: Option<uuid::Uuid>,
-    pub in_reply_to_url: Option<String>,
-    pub ap_id: Option<String>,
     pub visibility: String,
     pub content_warning: Option<String>,
     pub sensitive: bool,
@@ -45,8 +43,6 @@ impl From<ThoughtRow> for Thought {
             user_id: UserId::from_uuid(r.user_id),
             content: Content::new_remote(r.content),
             in_reply_to_id: r.in_reply_to_id.map(ThoughtId::from_uuid),
-            in_reply_to_url: r.in_reply_to_url,
-            ap_id: r.ap_id,
             visibility: Visibility::from_db_str(&r.visibility),
             content_warning: r.content_warning,
             sensitive: r.sensitive,
@@ -58,22 +54,20 @@ impl From<ThoughtRow> for Thought {
 }
 
 const THOUGHT_SELECT: &str =
-    "SELECT id,user_id,content,in_reply_to_id,in_reply_to_url,ap_id,visibility,content_warning,sensitive,local,created_at,updated_at FROM thoughts";
+    "SELECT id,user_id,content,in_reply_to_id,visibility,content_warning,sensitive,local,created_at,updated_at FROM thoughts";
 
 #[async_trait]
 impl ThoughtRepository for PgThoughtRepository {
     async fn save(&self, t: &Thought) -> Result<(), DomainError> {
         sqlx::query(
-            "INSERT INTO thoughts(id,user_id,content,in_reply_to_id,in_reply_to_url,ap_id,visibility,content_warning,sensitive,local,created_at)
-             VALUES($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11)
+            "INSERT INTO thoughts(id,user_id,content,in_reply_to_id,visibility,content_warning,sensitive,local,created_at)
+             VALUES($1,$2,$3,$4,$5,$6,$7,$8,$9)
              ON CONFLICT(id) DO UPDATE SET content=EXCLUDED.content,updated_at=NOW()"
         )
         .bind(t.id.as_uuid())
         .bind(t.user_id.as_uuid())
         .bind(t.content.as_str())
         .bind(t.in_reply_to_id.as_ref().map(|x| x.as_uuid()))
-        .bind(&t.in_reply_to_url)
-        .bind(&t.ap_id)
         .bind(t.visibility.as_str())
         .bind(&t.content_warning)
         .bind(t.sensitive)
@@ -121,11 +115,11 @@ impl ThoughtRepository for PgThoughtRepository {
         // Recursive CTE: fetches the root thought and all nested replies at any depth.
         sqlx::query_as::<_, ThoughtRow>(
             "WITH RECURSIVE thread AS (
-                SELECT id,user_id,content,in_reply_to_id,in_reply_to_url,ap_id,
+                SELECT id,user_id,content,in_reply_to_id,
                        visibility,content_warning,sensitive,local,created_at,updated_at
                 FROM thoughts WHERE id = $1
                 UNION ALL
-                SELECT t.id,t.user_id,t.content,t.in_reply_to_id,t.in_reply_to_url,t.ap_id,
+                SELECT t.id,t.user_id,t.content,t.in_reply_to_id,
                        t.visibility,t.content_warning,t.sensitive,t.local,t.created_at,t.updated_at
                 FROM thoughts t JOIN thread ON t.in_reply_to_id = thread.id
             )
diff --git a/crates/adapters/postgres/src/top_friend.rs b/crates/adapters/postgres/src/top_friend.rs
index 00c1356..a580c9e 100644
--- a/crates/adapters/postgres/src/top_friend.rs
+++ b/crates/adapters/postgres/src/top_friend.rs
@@ -58,15 +58,13 @@ impl TopFriendRepository for PgTopFriendRepository {
             header_url: Option<String>,
             custom_css: Option<String>,
             local: bool,
-            ap_id: Option<String>,
-            inbox_url: Option<String>,
             created_at: chrono::DateTime<chrono::Utc>,
             updated_at: chrono::DateTime<chrono::Utc>,
         }
         let rows = sqlx::query_as::<_, Row>(
             "SELECT tf.user_id AS tf_user_id, tf.friend_id, tf.position,
              u.id, u.username, u.email, u.password_hash, u.display_name, u.bio,
-             u.avatar_url, u.header_url, u.custom_css, u.local, u.ap_id, u.inbox_url,
+             u.avatar_url, u.header_url, u.custom_css, u.local,
              u.created_at, u.updated_at
              FROM top_friends tf JOIN users u ON u.id=tf.friend_id
              WHERE tf.user_id=$1 ORDER BY tf.position",
@@ -96,8 +94,6 @@ impl TopFriendRepository for PgTopFriendRepository {
                     header_url: r.header_url,
                     custom_css: r.custom_css,
                     local: r.local,
-                    ap_id: r.ap_id,
-                    inbox_url: r.inbox_url,
                     created_at: r.created_at,
                     updated_at: r.updated_at,
                 };
diff --git a/crates/adapters/postgres/src/user.rs b/crates/adapters/postgres/src/user.rs
index 85b1ed2..3d5bf93 100644
--- a/crates/adapters/postgres/src/user.rs
+++ b/crates/adapters/postgres/src/user.rs
@@ -30,8 +30,6 @@ pub struct UserRow {
     pub header_url: Option<String>,
     pub custom_css: Option<String>,
     pub local: bool,
-    pub ap_id: Option<String>,
-    pub inbox_url: Option<String>,
     pub created_at: DateTime<Utc>,
     pub updated_at: DateTime<Utc>,
 }
@@ -49,15 +47,15 @@ impl From<UserRow> for User {
             header_url: r.header_url,
             custom_css: r.custom_css,
             local: r.local,
-            ap_id: r.ap_id,
-            inbox_url: r.inbox_url,
             created_at: r.created_at,
             updated_at: r.updated_at,
         }
     }
 }
 
-pub const USER_SELECT: &str = "SELECT id,username,email,password_hash,display_name,bio,avatar_url,header_url,custom_css,local,ap_id,inbox_url,created_at,updated_at FROM users";
+pub const USER_SELECT: &str =
+    "SELECT id,username,email,password_hash,display_name,bio,avatar_url,header_url,\
+     custom_css,local,created_at,updated_at FROM users";
 
 #[async_trait]
 impl UserRepository for PgUserRepository {
@@ -90,14 +88,14 @@ impl UserRepository for PgUserRepository {
 
     async fn save(&self, user: &User) -> Result<(), DomainError> {
         sqlx::query(
-            "INSERT INTO users (id,username,email,password_hash,display_name,bio,avatar_url,header_url,custom_css,local,ap_id,inbox_url,created_at,updated_at)
-             VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14)
+            "INSERT INTO users (id,username,email,password_hash,display_name,bio,avatar_url,header_url,custom_css,local,created_at,updated_at)
+             VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12)
              ON CONFLICT(id) DO UPDATE SET
                username=EXCLUDED.username, email=EXCLUDED.email,
                password_hash=EXCLUDED.password_hash, display_name=EXCLUDED.display_name,
                bio=EXCLUDED.bio, avatar_url=EXCLUDED.avatar_url,
                header_url=EXCLUDED.header_url, custom_css=EXCLUDED.custom_css,
-               local=EXCLUDED.local, ap_id=EXCLUDED.ap_id, inbox_url=EXCLUDED.inbox_url,
+               local=EXCLUDED.local,
                updated_at=NOW()"
         )
         .bind(user.id.as_uuid())
@@ -110,8 +108,6 @@ impl UserRepository for PgUserRepository {
         .bind(&user.header_url)
         .bind(&user.custom_css)
         .bind(user.local)
-        .bind(&user.ap_id)
-        .bind(&user.inbox_url)
         .bind(user.created_at)
         .bind(user.updated_at)
         .execute(&self.pool)
diff --git a/crates/application/src/services/federation_event.rs b/crates/application/src/services/federation_event.rs
index 5fa432f..2b7d347 100644
--- a/crates/application/src/services/federation_event.rs
+++ b/crates/application/src/services/federation_event.rs
@@ -1,7 +1,7 @@
 use domain::{
     errors::DomainError,
     events::DomainEvent,
-    models::thought::{Thought, Visibility},
+    models::thought::Visibility,
     ports::{ActivityPubRepository, OutboundFederationPort, ThoughtRepository, UserRepository},
     value_objects::ThoughtId,
 };
@@ -18,11 +18,11 @@ pub struct FederationEventService {
 }
 
 impl FederationEventService {
-    fn object_ap_id(&self, thought: &Thought, thought_id: &ThoughtId) -> String {
-        thought
-            .ap_id
-            .clone()
-            .unwrap_or_else(|| format!("{}/thoughts/{}", self.base_url, thought_id))
+    async fn object_ap_id(&self, thought_id: &ThoughtId) -> Result<String, DomainError> {
+        if let Some(ap_id) = self.ap_repo.get_thought_ap_id(thought_id).await? {
+            return Ok(ap_id);
+        }
+        Ok(format!("{}/thoughts/{}", self.base_url, thought_id))
     }
 
     pub async fn process(&self, event: &DomainEvent) -> Result<(), DomainError> {
@@ -48,31 +48,24 @@ impl FederationEventService {
                     Some(u) => u,
                     None => return Ok(()),
                 };
-                // For replies to remote posts: in_reply_to_url is None but in_reply_to_id
-                // points to the locally-stored remote thought. Resolve its ap_id so the
-                // outbound Note includes inReplyTo and Mastodon threads it correctly.
-                let thought = if thought.in_reply_to_url.is_none() {
-                    if let Some(ref reply_id) = thought.in_reply_to_id {
-                        match self.thoughts.find_by_id(reply_id).await? {
-                            Some(parent) => {
-                                let parent_ap_url = parent.ap_id.unwrap_or_else(|| {
-                                    format!("{}/thoughts/{}", self.base_url, reply_id)
-                                });
-                                domain::models::thought::Thought {
-                                    in_reply_to_url: Some(parent_ap_url),
-                                    ..thought
-                                }
-                            }
-                            None => thought,
-                        }
-                    } else {
-                        thought
-                    }
+                // Resolve in_reply_to_url for the parent thought via AP repo.
+                let in_reply_to_url = if let Some(ref reply_id) = thought.in_reply_to_id {
+                    let ap_id = self
+                        .ap_repo
+                        .get_thought_ap_id(reply_id)
+                        .await?
+                        .unwrap_or_else(|| format!("{}/thoughts/{}", self.base_url, reply_id));
+                    Some(ap_id)
                 } else {
-                    thought
+                    None
                 };
                 self.ap
-                    .broadcast_create(user_id, &thought, user.username.as_str())
+                    .broadcast_create(
+                        user_id,
+                        &thought,
+                        user.username.as_str(),
+                        in_reply_to_url.as_deref(),
+                    )
                     .await
             }
 
@@ -106,8 +99,21 @@ impl FederationEventService {
                     Some(u) => u,
                     None => return Ok(()),
                 };
+                let in_reply_to_url = if let Some(ref reply_id) = thought.in_reply_to_id {
+                    self.ap_repo
+                        .get_thought_ap_id(reply_id)
+                        .await?
+                        .or_else(|| Some(format!("{}/thoughts/{}", self.base_url, reply_id)))
+                } else {
+                    None
+                };
                 self.ap
-                    .broadcast_update(user_id, &thought, user.username.as_str())
+                    .broadcast_update(
+                        user_id,
+                        &thought,
+                        user.username.as_str(),
+                        in_reply_to_url.as_deref(),
+                    )
                     .await
             }
 
@@ -122,11 +128,10 @@ impl FederationEventService {
                     _ => return Ok(()),
                 };
                 let _ = booster;
-                let thought = match self.thoughts.find_by_id(thought_id).await? {
-                    Some(t) => t,
-                    None => return Ok(()),
-                };
-                let object_ap_id = self.object_ap_id(&thought, thought_id);
+                if self.thoughts.find_by_id(thought_id).await?.is_none() {
+                    return Ok(());
+                }
+                let object_ap_id = self.object_ap_id(thought_id).await?;
                 self.ap.broadcast_announce(user_id, &object_ap_id).await
             }
 
@@ -134,11 +139,10 @@ impl FederationEventService {
                 user_id,
                 thought_id,
             } => {
-                let thought = match self.thoughts.find_by_id(thought_id).await? {
-                    Some(t) => t,
-                    None => return Ok(()),
-                };
-                let object_ap_id = self.object_ap_id(&thought, thought_id);
+                if self.thoughts.find_by_id(thought_id).await?.is_none() {
+                    return Ok(());
+                }
+                let object_ap_id = self.object_ap_id(thought_id).await?;
                 self.ap
                     .broadcast_undo_announce(user_id, &object_ap_id)
                     .await
@@ -262,17 +266,19 @@ impl FederationEventService {
                 };
                 let _ = liker;
                 let thought = match self.thoughts.find_by_id(thought_id).await? {
-                    Some(t) if t.ap_id.is_some() => t,
+                    Some(t) => t,
                     _ => return Ok(()),
                 };
-                let author = match self.users.find_by_id(&thought.user_id).await? {
-                    Some(u) if u.inbox_url.is_some() => u,
-                    _ => return Ok(()),
+                let thought_ap_id = match self.ap_repo.get_thought_ap_id(thought_id).await? {
+                    Some(id) => id,
+                    None => return Ok(()), // local thought — no federation needed
+                };
+                let actor_urls = match self.ap_repo.get_actor_ap_urls(&thought.user_id).await? {
+                    Some(u) => u,
+                    None => return Ok(()),
                 };
-                let object_ap_id = thought.ap_id.unwrap();
-                let inbox_url = author.inbox_url.unwrap();
                 self.ap
-                    .broadcast_like(user_id, &object_ap_id, &inbox_url)
+                    .broadcast_like(user_id, &thought_ap_id, &actor_urls.inbox_url)
                     .await
             }
 
@@ -286,17 +292,19 @@ impl FederationEventService {
                 };
                 let _ = liker;
                 let thought = match self.thoughts.find_by_id(thought_id).await? {
-                    Some(t) if t.ap_id.is_some() => t,
+                    Some(t) => t,
                     _ => return Ok(()),
                 };
-                let author = match self.users.find_by_id(&thought.user_id).await? {
-                    Some(u) if u.inbox_url.is_some() => u,
-                    _ => return Ok(()),
+                let thought_ap_id = match self.ap_repo.get_thought_ap_id(thought_id).await? {
+                    Some(id) => id,
+                    None => return Ok(()),
+                };
+                let actor_urls = match self.ap_repo.get_actor_ap_urls(&thought.user_id).await? {
+                    Some(u) => u,
+                    None => return Ok(()),
                 };
-                let object_ap_id = thought.ap_id.unwrap();
-                let inbox_url = author.inbox_url.unwrap();
                 self.ap
-                    .broadcast_undo_like(user_id, &object_ap_id, &inbox_url)
+                    .broadcast_undo_like(user_id, &thought_ap_id, &actor_urls.inbox_url)
                     .await
             }
 
@@ -345,6 +353,7 @@ mod tests {
             _: &UserId,
             thought: &Thought,
             _: &str,
+            _in_reply_to_url: Option<&str>,
         ) -> Result<(), DomainError> {
             self.created.lock().unwrap().push(thought.id.clone());
             Ok(())
@@ -358,6 +367,7 @@ mod tests {
             _: &UserId,
             thought: &Thought,
             _: &str,
+            _in_reply_to_url: Option<&str>,
         ) -> Result<(), DomainError> {
             self.updated.lock().unwrap().push(thought.id.clone());
             Ok(())
@@ -460,10 +470,9 @@ mod tests {
     async fn remote_thought_created_does_not_broadcast() {
         let store = TestStore::default();
         let alice = alice();
-        // Remote thought: local = false, ap_id = Some(...)
+        // Remote thought: local = false
         let mut thought = local_thought(alice.id.clone());
         thought.local = false;
-        thought.ap_id = Some("https://remote.example/notes/1".into());
         store.users.lock().unwrap().push(alice.clone());
         store.thoughts.lock().unwrap().push(thought.clone());
 
@@ -553,7 +562,10 @@ mod tests {
         let alice = alice();
         let mut thought = local_thought(alice.id.clone());
         thought.local = false;
-        thought.ap_id = Some("https://mastodon.social/users/bob/statuses/123".into());
+        store.thought_ap_ids.lock().unwrap().insert(
+            thought.id.clone(),
+            "https://mastodon.social/users/bob/statuses/123".into(),
+        );
         store.users.lock().unwrap().push(alice.clone());
         store.thoughts.lock().unwrap().push(thought.clone());
 
@@ -702,7 +714,10 @@ mod tests {
         let alice = alice();
         let mut thought = local_thought(alice.id.clone());
         thought.local = false;
-        thought.ap_id = Some("https://mastodon.social/users/bob/statuses/456".into());
+        store.thought_ap_ids.lock().unwrap().insert(
+            thought.id.clone(),
+            "https://mastodon.social/users/bob/statuses/456".into(),
+        );
         store.thoughts.lock().unwrap().push(thought.clone());
 
         let spy = Arc::new(SpyPort::default());
@@ -797,10 +812,19 @@ mod tests {
             PasswordHash("h".into()),
         );
         author.local = false;
-        author.inbox_url = Some("https://mastodon.social/users/author/inbox".into());
+        store.actor_ap_urls.lock().unwrap().insert(
+            author.id.clone(),
+            domain::ports::ActorApUrls {
+                ap_id: "https://mastodon.social/users/author".into(),
+                inbox_url: "https://mastodon.social/users/author/inbox".into(),
+            },
+        );
 
-        let mut thought = local_thought(author.id.clone());
-        thought.ap_id = Some("https://mastodon.social/posts/123".into());
+        let thought = local_thought(author.id.clone());
+        store.thought_ap_ids.lock().unwrap().insert(
+            thought.id.clone(),
+            "https://mastodon.social/posts/123".into(),
+        );
 
         let liker = alice();
 
diff --git a/crates/domain/src/models/thought.rs b/crates/domain/src/models/thought.rs
index d9980f7..2e99773 100644
--- a/crates/domain/src/models/thought.rs
+++ b/crates/domain/src/models/thought.rs
@@ -15,8 +15,6 @@ pub struct Thought {
     pub user_id: UserId,
     pub content: Content,
     pub in_reply_to_id: Option<ThoughtId>,
-    pub in_reply_to_url: Option<String>,
-    pub ap_id: Option<String>,
     pub visibility: Visibility,
     pub content_warning: Option<String>,
     pub sensitive: bool,
@@ -60,8 +58,6 @@ impl Thought {
             user_id,
             content,
             in_reply_to_id,
-            in_reply_to_url: None,
-            ap_id: None,
             visibility,
             content_warning,
             sensitive,
diff --git a/crates/domain/src/models/user.rs b/crates/domain/src/models/user.rs
index f5577c2..4e61f3c 100644
--- a/crates/domain/src/models/user.rs
+++ b/crates/domain/src/models/user.rs
@@ -13,8 +13,6 @@ pub struct User {
     pub header_url: Option<String>,
     pub custom_css: Option<String>,
     pub local: bool,
-    pub ap_id: Option<String>,
-    pub inbox_url: Option<String>,
     pub created_at: DateTime<Utc>,
     pub updated_at: DateTime<Utc>,
 }
@@ -38,8 +36,6 @@ impl User {
             header_url: None,
             custom_css: None,
             local: true,
-            ap_id: None,
-            inbox_url: None,
             created_at: now,
             updated_at: now,
         }
diff --git a/crates/domain/src/ports.rs b/crates/domain/src/ports.rs
index 93147b7..a3a4e95 100644
--- a/crates/domain/src/ports.rs
+++ b/crates/domain/src/ports.rs
@@ -442,6 +442,7 @@ pub trait OutboundFederationPort: Send + Sync {
         author_user_id: &UserId,
         thought: &Thought,
         author_username: &str,
+        in_reply_to_url: Option<&str>,
     ) -> Result<(), DomainError>;
 
     /// Fan out a Delete tombstone for a now-deleted local Note.
@@ -459,6 +460,7 @@ pub trait OutboundFederationPort: Send + Sync {
         author_user_id: &UserId,
         thought: &Thought,
         author_username: &str,
+        in_reply_to_url: Option<&str>,
     ) -> Result<(), DomainError>;
 
     /// Fan out an Announce(object_ap_id) for a boost.
diff --git a/crates/domain/src/testing.rs b/crates/domain/src/testing.rs
index 8fbce63..2c2bfb2 100644
--- a/crates/domain/src/testing.rs
+++ b/crates/domain/src/testing.rs
@@ -19,6 +19,7 @@ use crate::{
 };
 use async_trait::async_trait;
 use chrono::Utc;
+use std::collections::HashMap;
 use std::sync::{Arc, Mutex};
 use url;
 
@@ -35,6 +36,12 @@ pub struct TestStore {
     pub top_friends: Arc<Mutex<Vec<TopFriend>>>,
     pub notifications: Arc<Mutex<Vec<Notification>>>,
     pub events: Arc<Mutex<Vec<DomainEvent>>>,
+    /// AP URL → UserId for remote actors (used by find_remote_actor_id / intern_remote_actor)
+    pub actor_ap_ids: Arc<Mutex<HashMap<String, UserId>>>,
+    /// ThoughtId → AP object URL (used by get_thought_ap_id)
+    pub thought_ap_ids: Arc<Mutex<HashMap<ThoughtId, String>>>,
+    /// UserId → ActorApUrls (used by get_actor_ap_urls)
+    pub actor_ap_urls: Arc<Mutex<HashMap<UserId, ActorApUrls>>>,
 }
 
 #[async_trait]
@@ -802,14 +809,12 @@ impl ActivityPubRepository for TestStore {
         &self,
         actor_ap_url: &url::Url,
     ) -> Result<Option<UserId>, DomainError> {
-        let url = actor_ap_url.to_string();
         Ok(self
-            .users
+            .actor_ap_ids
             .lock()
             .unwrap()
-            .iter()
-            .find(|u| u.ap_id.as_deref() == Some(&url))
-            .map(|u| u.id.clone()))
+            .get(actor_ap_url.as_str())
+            .cloned())
     }
     async fn intern_remote_actor(&self, actor_ap_url: &url::Url) -> Result<UserId, DomainError> {
         if let Some(uid) = self.find_remote_actor_id(actor_ap_url).await? {
@@ -831,12 +836,14 @@ impl ActivityPubRepository for TestStore {
             header_url: None,
             custom_css: None,
             local: false,
-            ap_id: Some(actor_ap_url.to_string()),
-            inbox_url: None,
             created_at: chrono::Utc::now(),
             updated_at: chrono::Utc::now(),
         };
         self.users.lock().unwrap().push(user);
+        self.actor_ap_ids
+            .lock()
+            .unwrap()
+            .insert(actor_ap_url.to_string(), uid.clone());
         Ok(uid)
     }
     async fn update_remote_actor_display(
@@ -884,15 +891,15 @@ impl ActivityPubRepository for TestStore {
     }
     async fn get_thought_ap_id(
         &self,
-        _thought_id: &ThoughtId,
+        thought_id: &ThoughtId,
     ) -> Result<Option<String>, DomainError> {
-        Ok(None)
+        Ok(self.thought_ap_ids.lock().unwrap().get(thought_id).cloned())
     }
     async fn get_actor_ap_urls(
         &self,
-        _user_id: &UserId,
+        user_id: &UserId,
     ) -> Result<Option<ActorApUrls>, DomainError> {
-        Ok(None)
+        Ok(self.actor_ap_urls.lock().unwrap().get(user_id).cloned())
     }
 }
 
diff --git a/crates/presentation/src/handlers/feed.rs b/crates/presentation/src/handlers/feed.rs
index db6907c..b9f279c 100644
--- a/crates/presentation/src/handlers/feed.rs
+++ b/crates/presentation/src/handlers/feed.rs
@@ -26,7 +26,7 @@ pub fn to_thought_response(e: &domain::models::feed::FeedEntry) -> ThoughtRespon
         content: e.thought.content.as_str().to_string(),
         author: to_user_response(&e.author),
         in_reply_to_id: e.thought.in_reply_to_id.as_ref().map(|id| id.as_uuid()),
-        in_reply_to_url: e.thought.in_reply_to_url.clone(),
+        in_reply_to_url: None,
         visibility: e.thought.visibility.as_str().to_string(),
         content_warning: e.thought.content_warning.clone(),
         sensitive: e.thought.sensitive,