diff --git a/crates/adapters/jellyfin/src/lib.rs b/crates/adapters/jellyfin/src/lib.rs
index 1ee790bf..3ff9cc91 100644
--- a/crates/adapters/jellyfin/src/lib.rs
+++ b/crates/adapters/jellyfin/src/lib.rs
@@ -60,73 +60,5 @@ struct JellyfinPayload {
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn parses_valid_playback_stop() {
-        let body = serde_json::json!({
-            "NotificationType": "PlaybackStop",
-            "ItemType": "Movie",
-            "Name": "Blade Runner",
-            "Year": 1982,
-            "PlayedToCompletion": true,
-            "Provider_tmdb": "78",
-            "Provider_imdb": "tt0083658"
-        });
-        let parser = JellyfinParser;
-        let result = parser
-            .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
-            .unwrap();
-        let event = result.expect("should parse");
-        assert_eq!(event.title, "Blade Runner");
-        assert_eq!(event.year, Some(1982));
-        assert_eq!(event.tmdb_id, Some("tmdb:78".into()));
-        assert_eq!(event.imdb_id, Some("tt0083658".into()));
-    }
-
-    #[test]
-    fn ignores_non_movie() {
-        let body = serde_json::json!({
-            "NotificationType": "PlaybackStop",
-            "ItemType": "Episode",
-            "Name": "Some Episode",
-            "PlayedToCompletion": true
-        });
-        let parser = JellyfinParser;
-        let result = parser
-            .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
-            .unwrap();
-        assert!(result.is_none());
-    }
-
-    #[test]
-    fn ignores_incomplete_playback() {
-        let body = serde_json::json!({
-            "NotificationType": "PlaybackStop",
-            "ItemType": "Movie",
-            "Name": "Blade Runner",
-            "PlayedToCompletion": false
-        });
-        let parser = JellyfinParser;
-        let result = parser
-            .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
-            .unwrap();
-        assert!(result.is_none());
-    }
-
-    #[test]
-    fn ignores_playback_start() {
-        let body = serde_json::json!({
-            "NotificationType": "PlaybackStart",
-            "ItemType": "Movie",
-            "Name": "Blade Runner",
-            "PlayedToCompletion": false
-        });
-        let parser = JellyfinParser;
-        let result = parser
-            .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
-            .unwrap();
-        assert!(result.is_none());
-    }
-}
+#[path = "tests/lib.rs"]
+mod tests;
diff --git a/crates/adapters/jellyfin/src/tests/lib.rs b/crates/adapters/jellyfin/src/tests/lib.rs
new file mode 100644
index 00000000..9511eb78
--- /dev/null
+++ b/crates/adapters/jellyfin/src/tests/lib.rs
@@ -0,0 +1,68 @@
+use super::*;
+
+#[test]
+fn parses_valid_playback_stop() {
+    let body = serde_json::json!({
+        "NotificationType": "PlaybackStop",
+        "ItemType": "Movie",
+        "Name": "Blade Runner",
+        "Year": 1982,
+        "PlayedToCompletion": true,
+        "Provider_tmdb": "78",
+        "Provider_imdb": "tt0083658"
+    });
+    let parser = JellyfinParser;
+    let result = parser
+        .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
+        .unwrap();
+    let event = result.expect("should parse");
+    assert_eq!(event.title, "Blade Runner");
+    assert_eq!(event.year, Some(1982));
+    assert_eq!(event.tmdb_id, Some("tmdb:78".into()));
+    assert_eq!(event.imdb_id, Some("tt0083658".into()));
+}
+
+#[test]
+fn ignores_non_movie() {
+    let body = serde_json::json!({
+        "NotificationType": "PlaybackStop",
+        "ItemType": "Episode",
+        "Name": "Some Episode",
+        "PlayedToCompletion": true
+    });
+    let parser = JellyfinParser;
+    let result = parser
+        .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
+        .unwrap();
+    assert!(result.is_none());
+}
+
+#[test]
+fn ignores_incomplete_playback() {
+    let body = serde_json::json!({
+        "NotificationType": "PlaybackStop",
+        "ItemType": "Movie",
+        "Name": "Blade Runner",
+        "PlayedToCompletion": false
+    });
+    let parser = JellyfinParser;
+    let result = parser
+        .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
+        .unwrap();
+    assert!(result.is_none());
+}
+
+#[test]
+fn ignores_playback_start() {
+    let body = serde_json::json!({
+        "NotificationType": "PlaybackStart",
+        "ItemType": "Movie",
+        "Name": "Blade Runner",
+        "PlayedToCompletion": false
+    });
+    let parser = JellyfinParser;
+    let result = parser
+        .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
+        .unwrap();
+    assert!(result.is_none());
+}
diff --git a/crates/adapters/plex/src/lib.rs b/crates/adapters/plex/src/lib.rs
index 685b4108..2c6dfc05 100644
--- a/crates/adapters/plex/src/lib.rs
+++ b/crates/adapters/plex/src/lib.rs
@@ -70,100 +70,5 @@ struct PlexGuid {
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn parses_movie_scrobble() {
-        let body = serde_json::json!({
-            "event": "media.scrobble",
-            "Metadata": {
-                "type": "movie",
-                "title": "Blade Runner",
-                "year": 1982,
-                "Guid": [
-                    {"id": "tmdb://78"},
-                    {"id": "imdb://tt0083658"}
-                ]
-            }
-        });
-        let parser = PlexParser;
-        let result = parser
-            .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
-            .unwrap();
-        let event = result.expect("should parse");
-        assert_eq!(event.title, "Blade Runner");
-        assert_eq!(event.year, Some(1982));
-        assert_eq!(event.tmdb_id, Some("tmdb:78".into()));
-        assert_eq!(event.imdb_id, Some("tt0083658".into()));
-    }
-
-    #[test]
-    fn ignores_tv_episode() {
-        let body = serde_json::json!({
-            "event": "media.scrobble",
-            "Metadata": {
-                "type": "episode",
-                "title": "Pilot",
-                "grandparentTitle": "Breaking Bad",
-                "year": 2008,
-                "Guid": []
-            }
-        });
-        let parser = PlexParser;
-        let result = parser
-            .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
-            .unwrap();
-        assert!(result.is_none());
-    }
-
-    #[test]
-    fn ignores_play_event() {
-        let body = serde_json::json!({
-            "event": "media.play",
-            "Metadata": {
-                "type": "movie",
-                "title": "Blade Runner",
-                "year": 1982,
-                "Guid": []
-            }
-        });
-        let parser = PlexParser;
-        let result = parser
-            .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
-            .unwrap();
-        assert!(result.is_none());
-    }
-
-    #[test]
-    fn handles_no_guids() {
-        let body = serde_json::json!({
-            "event": "media.scrobble",
-            "Metadata": {
-                "type": "movie",
-                "title": "Some Indie Film",
-                "year": 2023
-            }
-        });
-        let parser = PlexParser;
-        let result = parser
-            .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
-            .unwrap();
-        let event = result.expect("should parse");
-        assert_eq!(event.title, "Some Indie Film");
-        assert!(event.tmdb_id.is_none());
-        assert!(event.imdb_id.is_none());
-    }
-
-    #[test]
-    fn handles_missing_metadata() {
-        let body = serde_json::json!({
-            "event": "media.scrobble"
-        });
-        let parser = PlexParser;
-        let result = parser
-            .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
-            .unwrap();
-        assert!(result.is_none());
-    }
-}
+#[path = "tests/lib.rs"]
+mod tests;
diff --git a/crates/adapters/plex/src/tests/lib.rs b/crates/adapters/plex/src/tests/lib.rs
new file mode 100644
index 00000000..2459f256
--- /dev/null
+++ b/crates/adapters/plex/src/tests/lib.rs
@@ -0,0 +1,95 @@
+use super::*;
+
+#[test]
+fn parses_movie_scrobble() {
+    let body = serde_json::json!({
+        "event": "media.scrobble",
+        "Metadata": {
+            "type": "movie",
+            "title": "Blade Runner",
+            "year": 1982,
+            "Guid": [
+                {"id": "tmdb://78"},
+                {"id": "imdb://tt0083658"}
+            ]
+        }
+    });
+    let parser = PlexParser;
+    let result = parser
+        .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
+        .unwrap();
+    let event = result.expect("should parse");
+    assert_eq!(event.title, "Blade Runner");
+    assert_eq!(event.year, Some(1982));
+    assert_eq!(event.tmdb_id, Some("tmdb:78".into()));
+    assert_eq!(event.imdb_id, Some("tt0083658".into()));
+}
+
+#[test]
+fn ignores_tv_episode() {
+    let body = serde_json::json!({
+        "event": "media.scrobble",
+        "Metadata": {
+            "type": "episode",
+            "title": "Pilot",
+            "grandparentTitle": "Breaking Bad",
+            "year": 2008,
+            "Guid": []
+        }
+    });
+    let parser = PlexParser;
+    let result = parser
+        .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
+        .unwrap();
+    assert!(result.is_none());
+}
+
+#[test]
+fn ignores_play_event() {
+    let body = serde_json::json!({
+        "event": "media.play",
+        "Metadata": {
+            "type": "movie",
+            "title": "Blade Runner",
+            "year": 1982,
+            "Guid": []
+        }
+    });
+    let parser = PlexParser;
+    let result = parser
+        .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
+        .unwrap();
+    assert!(result.is_none());
+}
+
+#[test]
+fn handles_no_guids() {
+    let body = serde_json::json!({
+        "event": "media.scrobble",
+        "Metadata": {
+            "type": "movie",
+            "title": "Some Indie Film",
+            "year": 2023
+        }
+    });
+    let parser = PlexParser;
+    let result = parser
+        .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
+        .unwrap();
+    let event = result.expect("should parse");
+    assert_eq!(event.title, "Some Indie Film");
+    assert!(event.tmdb_id.is_none());
+    assert!(event.imdb_id.is_none());
+}
+
+#[test]
+fn handles_missing_metadata() {
+    let body = serde_json::json!({
+        "event": "media.scrobble"
+    });
+    let parser = PlexParser;
+    let result = parser
+        .parse_playback_event(serde_json::to_vec(&body).unwrap().as_slice())
+        .unwrap();
+    assert!(result.is_none());
+}
diff --git a/crates/adapters/rss/src/lib.rs b/crates/adapters/rss/src/lib.rs
index d11d5ff8..87057c4e 100644
--- a/crates/adapters/rss/src/lib.rs
+++ b/crates/adapters/rss/src/lib.rs
@@ -1,3 +1,4 @@
+use domain::errors::DomainError;
 use domain::models::DiaryEntry;
 use domain::ports::{FeedChannel, RssFeedRenderer};
 use rss_feed::extension::atom::{self, AtomExtensionBuilder, Link};
@@ -24,7 +25,7 @@ impl RssFeedRenderer for RssAdapter {
         &self,
         entries: &[DiaryEntry],
         channel: &FeedChannel<'_>,
-    ) -> Result<String, String> {
+    ) -> Result<String, DomainError> {
         let items = entries
             .iter()
             .map(|e| {
diff --git a/crates/api-types/src/social.rs b/crates/api-types/src/social.rs
index 94af24e0..f7172b78 100644
--- a/crates/api-types/src/social.rs
+++ b/crates/api-types/src/social.rs
@@ -78,28 +78,6 @@ pub struct PendingCountResponse {
     pub count: usize,
 }
 
-//todo: move out to separate file
 #[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn follow_state_dto_serializes_to_lowercase_strings() {
-        assert_eq!(
-            serde_json::to_string(&FollowStateDto::None).unwrap(),
-            "\"none\""
-        );
-        assert_eq!(
-            serde_json::to_string(&FollowStateDto::Pending).unwrap(),
-            "\"pending\""
-        );
-        assert_eq!(
-            serde_json::to_string(&FollowStateDto::Accepted).unwrap(),
-            "\"accepted\""
-        );
-        assert_eq!(
-            serde_json::to_string(&FollowStateDto::Rejected).unwrap(),
-            "\"rejected\""
-        );
-    }
-}
+#[path = "tests/social.rs"]
+mod tests;
diff --git a/crates/api-types/src/tests/social.rs b/crates/api-types/src/tests/social.rs
new file mode 100644
index 00000000..2e09621b
--- /dev/null
+++ b/crates/api-types/src/tests/social.rs
@@ -0,0 +1,21 @@
+use super::*;
+
+#[test]
+fn follow_state_dto_serializes_to_lowercase_strings() {
+    assert_eq!(
+        serde_json::to_string(&FollowStateDto::None).unwrap(),
+        "\"none\""
+    );
+    assert_eq!(
+        serde_json::to_string(&FollowStateDto::Pending).unwrap(),
+        "\"pending\""
+    );
+    assert_eq!(
+        serde_json::to_string(&FollowStateDto::Accepted).unwrap(),
+        "\"accepted\""
+    );
+    assert_eq!(
+        serde_json::to_string(&FollowStateDto::Rejected).unwrap(),
+        "\"rejected\""
+    );
+}
diff --git a/crates/application/src/import/execute.rs b/crates/application/src/import/execute.rs
index 6480cde3..73df7b7a 100644
--- a/crates/application/src/import/execute.rs
+++ b/crates/application/src/import/execute.rs
@@ -44,7 +44,8 @@ pub async fn execute(
     let mut failed = Vec::new();
 
     let semaphore = Arc::new(tokio::sync::Semaphore::new(CONCURRENCY_LIMIT));
-    let mut tasks: tokio::task::JoinSet<(usize, Result<(), String>)> = tokio::task::JoinSet::new();
+    let mut tasks: tokio::task::JoinSet<(usize, Result<(), DomainError>)> =
+        tokio::task::JoinSet::new();
 
     for (idx, annotated) in row_results.into_iter().enumerate() {
         if !confirmed_set.contains(&idx) {
@@ -56,12 +57,12 @@ pub async fn execute(
                 failed.push((idx, errors.join("; ")));
             }
             RowResult::Valid(row) => match row_to_command(&row, user_id.value()) {
-                Err(e) => failed.push((idx, e)),
+                Err(e) => failed.push((idx, import_error_message(e))),
                 Ok(log_cmd) => {
                     let permit = Arc::clone(&semaphore).acquire_owned().await.unwrap();
                     let logger = deps.review_logger.clone();
                     tasks.spawn(async move {
-                        let result = logger.log_review(log_cmd).await.map_err(|e| e.to_string());
+                        let result = logger.log_review(log_cmd).await;
                         drop(permit);
                         (idx, result)
                     });
@@ -74,7 +75,7 @@ pub async fn execute(
         let (idx, outcome) = res.expect("import task panicked");
         match outcome {
             Ok(()) => imported += 1,
-            Err(e) => failed.push((idx, e)),
+            Err(e) => failed.push((idx, e.to_string())),
         }
     }
 
@@ -91,20 +92,36 @@ pub async fn execute(
 #[path = "tests/execute.rs"]
 mod tests;
 
-fn row_to_command(row: &ImportRow, user_id: Uuid) -> Result<LogReviewCommand, String> {
+/// Row-level validation failures keep their bare message in the summary.
+fn import_error_message(e: DomainError) -> String {
+    match e {
+        DomainError::ValidationError(msg) => msg,
+        other => other.to_string(),
+    }
+}
+
+fn row_to_command(row: &ImportRow, user_id: Uuid) -> Result<LogReviewCommand, DomainError> {
     let rating = row
         .rating
         .as_deref()
-        .ok_or("missing rating")?
+        .ok_or_else(|| DomainError::ValidationError("missing rating".into()))?
         .parse::<u8>()
-        .map_err(|_| "rating is not a valid u8".to_string())?;
+        .map_err(|_| DomainError::ValidationError("rating is not a valid u8".into()))?;
 
-    let watched_at_str = row.watched_at.as_deref().ok_or("missing watched_at")?;
+    let watched_at_str = row
+        .watched_at
+        .as_deref()
+        .ok_or_else(|| DomainError::ValidationError("missing watched_at".into()))?;
     let watched_at =
         NaiveDateTime::parse_from_str(&format!("{} 00:00:00", watched_at_str), "%Y-%m-%d %H:%M:%S")
             .or_else(|_| NaiveDateTime::parse_from_str(watched_at_str, "%Y-%m-%d %H:%M:%S"))
             .or_else(|_| NaiveDateTime::parse_from_str(watched_at_str, "%Y-%m-%dT%H:%M:%S"))
-            .map_err(|_| format!("cannot parse watched_at: '{}'", watched_at_str))?;
+            .map_err(|_| {
+                DomainError::ValidationError(format!(
+                    "cannot parse watched_at: '{}'",
+                    watched_at_str
+                ))
+            })?;
 
     Ok(LogReviewCommand {
         user_id,
diff --git a/crates/application/src/users/diary_filter.rs b/crates/application/src/users/diary_filter.rs
index 326b9cf2..e52744e8 100644
--- a/crates/application/src/users/diary_filter.rs
+++ b/crates/application/src/users/diary_filter.rs
@@ -38,43 +38,5 @@ pub(super) fn paged_user_filter(
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn feed_sort_to_direction_all_variants() {
-        assert!(matches!(
-            feed_sort_to_direction(FeedSortBy::Date),
-            ReviewSortBy::Descending
-        ));
-        assert!(matches!(
-            feed_sort_to_direction(FeedSortBy::DateAsc),
-            ReviewSortBy::Ascending
-        ));
-        assert!(matches!(
-            feed_sort_to_direction(FeedSortBy::Rating),
-            ReviewSortBy::ByRatingDesc
-        ));
-        assert!(matches!(
-            feed_sort_to_direction(FeedSortBy::RatingAsc),
-            ReviewSortBy::ByRatingAsc
-        ));
-    }
-
-    #[test]
-    fn paged_user_filter_builds_correctly() {
-        let uid = UserId::from_uuid(uuid::Uuid::new_v4());
-        let filter = paged_user_filter(
-            uid.clone(),
-            ReviewSortBy::Descending,
-            Some(20),
-            Some(5),
-            Some("blade".into()),
-            false,
-        )
-        .unwrap();
-
-        assert_eq!(filter.user_id.unwrap().value(), uid.value());
-        assert_eq!(filter.search.as_deref(), Some("blade"));
-    }
-}
+#[path = "tests/diary_filter.rs"]
+mod tests;
diff --git a/crates/application/src/users/tests/diary_filter.rs b/crates/application/src/users/tests/diary_filter.rs
new file mode 100644
index 00000000..1bdbe433
--- /dev/null
+++ b/crates/application/src/users/tests/diary_filter.rs
@@ -0,0 +1,38 @@
+use super::*;
+
+#[test]
+fn feed_sort_to_direction_all_variants() {
+    assert!(matches!(
+        feed_sort_to_direction(FeedSortBy::Date),
+        ReviewSortBy::Descending
+    ));
+    assert!(matches!(
+        feed_sort_to_direction(FeedSortBy::DateAsc),
+        ReviewSortBy::Ascending
+    ));
+    assert!(matches!(
+        feed_sort_to_direction(FeedSortBy::Rating),
+        ReviewSortBy::ByRatingDesc
+    ));
+    assert!(matches!(
+        feed_sort_to_direction(FeedSortBy::RatingAsc),
+        ReviewSortBy::ByRatingAsc
+    ));
+}
+
+#[test]
+fn paged_user_filter_builds_correctly() {
+    let uid = UserId::from_uuid(uuid::Uuid::new_v4());
+    let filter = paged_user_filter(
+        uid.clone(),
+        ReviewSortBy::Descending,
+        Some(20),
+        Some(5),
+        Some("blade".into()),
+        false,
+    )
+    .unwrap();
+
+    assert_eq!(filter.user_id.unwrap().value(), uid.value());
+    assert_eq!(filter.search.as_deref(), Some("blade"));
+}
diff --git a/crates/domain/src/ports/federation.rs b/crates/domain/src/ports/federation.rs
index 6ec92eb4..9c944d8a 100644
--- a/crates/domain/src/ports/federation.rs
+++ b/crates/domain/src/ports/federation.rs
@@ -51,47 +51,5 @@ pub trait ApBackfillPort: Send + Sync {
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::ports::noop::{NoopApBackfill, NoopApDocument, NoopInstanceBlocklist};
-
-    #[tokio::test]
-    async fn noop_document_returns_empty_strings() {
-        let p = NoopApDocument;
-        assert_eq!(p.actor_json("anything").await.unwrap(), "");
-        assert_eq!(
-            p.followers_collection_json(uuid::Uuid::nil(), None)
-                .await
-                .unwrap(),
-            ""
-        );
-        assert_eq!(
-            p.following_collection_json(uuid::Uuid::nil(), Some(2))
-                .await
-                .unwrap(),
-            ""
-        );
-    }
-
-    #[tokio::test]
-    async fn noop_blocklist_returns_empty_and_ok() {
-        let p = NoopInstanceBlocklist;
-        assert!(p.get_blocked_domains().await.unwrap().is_empty());
-        p.add_blocked_domain("evil.example", Some("spam"))
-            .await
-            .unwrap();
-        p.remove_blocked_domain("evil.example").await.unwrap();
-    }
-
-    #[tokio::test]
-    async fn noop_backfill_returns_empty_and_ok() {
-        let p = NoopApBackfill;
-        assert!(p.get_following(uuid::Uuid::nil()).await.unwrap().is_empty());
-        p.import_remote_outbox("https://a/outbox", "https://a")
-            .await
-            .unwrap();
-        p.run_backfill_for_follower(uuid::Uuid::nil(), "https://a/inbox".into())
-            .await
-            .unwrap();
-    }
-}
+#[path = "tests/federation.rs"]
+mod tests;
diff --git a/crates/domain/src/ports/rss.rs b/crates/domain/src/ports/rss.rs
index 3062a934..1e4a37f0 100644
--- a/crates/domain/src/ports/rss.rs
+++ b/crates/domain/src/ports/rss.rs
@@ -1,3 +1,4 @@
+use crate::errors::DomainError;
 use crate::models::DiaryEntry;
 
 /// Channel-level metadata for a rendered feed. Paths are site-relative
@@ -15,5 +16,5 @@ pub trait RssFeedRenderer: Send + Sync {
         &self,
         entries: &[DiaryEntry],
         channel: &FeedChannel<'_>,
-    ) -> Result<String, String>;
+    ) -> Result<String, DomainError>;
 }
diff --git a/crates/domain/src/ports/tests/federation.rs b/crates/domain/src/ports/tests/federation.rs
new file mode 100644
index 00000000..052cf14b
--- /dev/null
+++ b/crates/domain/src/ports/tests/federation.rs
@@ -0,0 +1,42 @@
+use super::*;
+use crate::ports::noop::{NoopApBackfill, NoopApDocument, NoopInstanceBlocklist};
+
+#[tokio::test]
+async fn noop_document_returns_empty_strings() {
+    let p = NoopApDocument;
+    assert_eq!(p.actor_json("anything").await.unwrap(), "");
+    assert_eq!(
+        p.followers_collection_json(uuid::Uuid::nil(), None)
+            .await
+            .unwrap(),
+        ""
+    );
+    assert_eq!(
+        p.following_collection_json(uuid::Uuid::nil(), Some(2))
+            .await
+            .unwrap(),
+        ""
+    );
+}
+
+#[tokio::test]
+async fn noop_blocklist_returns_empty_and_ok() {
+    let p = NoopInstanceBlocklist;
+    assert!(p.get_blocked_domains().await.unwrap().is_empty());
+    p.add_blocked_domain("evil.example", Some("spam"))
+        .await
+        .unwrap();
+    p.remove_blocked_domain("evil.example").await.unwrap();
+}
+
+#[tokio::test]
+async fn noop_backfill_returns_empty_and_ok() {
+    let p = NoopApBackfill;
+    assert!(p.get_following(uuid::Uuid::nil()).await.unwrap().is_empty());
+    p.import_remote_outbox("https://a/outbox", "https://a")
+        .await
+        .unwrap();
+    p.run_backfill_for_follower(uuid::Uuid::nil(), "https://a/inbox".into())
+        .await
+        .unwrap();
+}
diff --git a/crates/presentation/src/handlers/rss.rs b/crates/presentation/src/handlers/rss.rs
index ed4d13e4..847b73ff 100644
--- a/crates/presentation/src/handlers/rss.rs
+++ b/crates/presentation/src/handlers/rss.rs
@@ -6,7 +6,7 @@ use axum::{
 use uuid::Uuid;
 
 use application::{diary::get_diary, diary::get_user_feed, diary::queries::GetDiaryQuery};
-use domain::{errors::DomainError, models::ReviewSortBy, ports::FeedChannel};
+use domain::{models::ReviewSortBy, ports::FeedChannel};
 
 use crate::{errors::ApiError, state::AppState};
 
@@ -29,7 +29,7 @@ pub async fn get_feed(State(state): State<AppState>) -> Result<impl IntoResponse
                 self_path: "/feed.rss",
             },
         )
-        .map_err(|e| ApiError(DomainError::InfrastructureError(e)))?;
+        .map_err(ApiError)?;
     Ok((
         [(header::CONTENT_TYPE, "application/xml; charset=utf-8")],
         xml,
@@ -61,7 +61,7 @@ pub async fn get_user_feed(
                 self_path: &self_path,
             },
         )
-        .map_err(|e| ApiError(DomainError::InfrastructureError(e)))?;
+        .map_err(ApiError)?;
 
     Ok((
         [(header::CONTENT_TYPE, "application/xml; charset=utf-8")],
diff --git a/crates/presentation/src/handlers/social.rs b/crates/presentation/src/handlers/social.rs
index cf978a89..4256d292 100644
--- a/crates/presentation/src/handlers/social.rs
+++ b/crates/presentation/src/handlers/social.rs
@@ -1091,105 +1091,5 @@ pub async fn post_unblock_actor(
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-    use domain::value_objects::{InstanceIdentity, SocialActor, SocialIdentity, UserId};
-
-    fn local_actor(uid: &UserId) -> SocialActor {
-        SocialActor {
-            identity: SocialIdentity::Local(uid.clone()),
-            handle: "@gabriel@md.example".into(),
-            display_name: None,
-            avatar_url: None,
-        }
-    }
-
-    #[test]
-    fn local_actor_dto_url_round_trips_back_to_the_same_identity() {
-        let instance = InstanceIdentity::new("https://md.example");
-        let uid = UserId::from_uuid(uuid::Uuid::new_v4());
-
-        let dto = social_actor_to_dto(local_actor(&uid), &instance);
-
-        assert!(!dto.url.starts_with("local:"), "url was {}", dto.url);
-        assert_eq!(
-            instance.identify(&dto.url),
-            SocialIdentity::Local(uid),
-            "a local actor's dto url must parse back as Local"
-        );
-    }
-
-    #[cfg(feature = "federation")]
-    #[test]
-    fn local_blocked_dto_url_round_trips_back_to_the_same_identity() {
-        let instance = InstanceIdentity::new("https://md.example");
-        let uid = UserId::from_uuid(uuid::Uuid::new_v4());
-
-        let dto = social_actor_to_blocked_dto(local_actor(&uid), &instance);
-
-        assert!(!dto.url.starts_with("local:"), "url was {}", dto.url);
-        assert_eq!(instance.identify(&dto.url), SocialIdentity::Local(uid));
-    }
-
-    #[test]
-    fn local_template_url_round_trips_back_to_the_same_identity() {
-        let instance = InstanceIdentity::new("https://md.example");
-        let uid = UserId::from_uuid(uuid::Uuid::new_v4());
-
-        let data = social_actor_to_template(local_actor(&uid), &instance);
-
-        assert!(!data.url.starts_with("local:"), "url was {}", data.url);
-        assert_eq!(instance.identify(&data.url), SocialIdentity::Local(uid));
-    }
-
-    #[test]
-    fn remote_actor_dto_url_is_passed_through_unchanged() {
-        let instance = InstanceIdentity::new("https://md.example");
-        let actor = SocialActor {
-            identity: SocialIdentity::Remote {
-                actor_url: "https://other.example/users/bob".into(),
-            },
-            handle: "@bob@other.example".into(),
-            display_name: None,
-            avatar_url: None,
-        };
-
-        let dto = social_actor_to_dto(actor, &instance);
-
-        assert_eq!(dto.url, "https://other.example/users/bob");
-    }
-
-    #[test]
-    fn local_actor_dto_carries_user_id_and_avatar() {
-        let instance = InstanceIdentity::new("https://md.example");
-        let uid = UserId::from_uuid(uuid::Uuid::new_v4());
-        let mut actor = local_actor(&uid);
-        actor.avatar_url = Some("https://md.example/images/a.webp".into());
-
-        let dto = social_actor_to_dto(actor, &instance);
-
-        assert_eq!(
-            dto.user_id,
-            Some(uid.value()),
-            "local actors must carry user_id for internal links"
-        );
-        assert_eq!(
-            dto.avatar_url.as_deref(),
-            Some("https://md.example/images/a.webp")
-        );
-    }
-
-    #[test]
-    fn remote_actor_dto_has_no_user_id() {
-        let instance = InstanceIdentity::new("https://md.example");
-        let actor = SocialActor {
-            identity: SocialIdentity::Remote {
-                actor_url: "https://other.example/users/bob".into(),
-            },
-            handle: "@bob@other.example".into(),
-            display_name: None,
-            avatar_url: None,
-        };
-        assert_eq!(social_actor_to_dto(actor, &instance).user_id, None);
-    }
-}
+#[path = "tests/social.rs"]
+mod tests;
diff --git a/crates/presentation/src/handlers/tests/social.rs b/crates/presentation/src/handlers/tests/social.rs
new file mode 100644
index 00000000..5c4999bf
--- /dev/null
+++ b/crates/presentation/src/handlers/tests/social.rs
@@ -0,0 +1,100 @@
+use super::*;
+use domain::value_objects::{InstanceIdentity, SocialActor, SocialIdentity, UserId};
+
+fn local_actor(uid: &UserId) -> SocialActor {
+    SocialActor {
+        identity: SocialIdentity::Local(uid.clone()),
+        handle: "@gabriel@md.example".into(),
+        display_name: None,
+        avatar_url: None,
+    }
+}
+
+#[test]
+fn local_actor_dto_url_round_trips_back_to_the_same_identity() {
+    let instance = InstanceIdentity::new("https://md.example");
+    let uid = UserId::from_uuid(uuid::Uuid::new_v4());
+
+    let dto = social_actor_to_dto(local_actor(&uid), &instance);
+
+    assert!(!dto.url.starts_with("local:"), "url was {}", dto.url);
+    assert_eq!(
+        instance.identify(&dto.url),
+        SocialIdentity::Local(uid),
+        "a local actor's dto url must parse back as Local"
+    );
+}
+
+#[cfg(feature = "federation")]
+#[test]
+fn local_blocked_dto_url_round_trips_back_to_the_same_identity() {
+    let instance = InstanceIdentity::new("https://md.example");
+    let uid = UserId::from_uuid(uuid::Uuid::new_v4());
+
+    let dto = social_actor_to_blocked_dto(local_actor(&uid), &instance);
+
+    assert!(!dto.url.starts_with("local:"), "url was {}", dto.url);
+    assert_eq!(instance.identify(&dto.url), SocialIdentity::Local(uid));
+}
+
+#[test]
+fn local_template_url_round_trips_back_to_the_same_identity() {
+    let instance = InstanceIdentity::new("https://md.example");
+    let uid = UserId::from_uuid(uuid::Uuid::new_v4());
+
+    let data = social_actor_to_template(local_actor(&uid), &instance);
+
+    assert!(!data.url.starts_with("local:"), "url was {}", data.url);
+    assert_eq!(instance.identify(&data.url), SocialIdentity::Local(uid));
+}
+
+#[test]
+fn remote_actor_dto_url_is_passed_through_unchanged() {
+    let instance = InstanceIdentity::new("https://md.example");
+    let actor = SocialActor {
+        identity: SocialIdentity::Remote {
+            actor_url: "https://other.example/users/bob".into(),
+        },
+        handle: "@bob@other.example".into(),
+        display_name: None,
+        avatar_url: None,
+    };
+
+    let dto = social_actor_to_dto(actor, &instance);
+
+    assert_eq!(dto.url, "https://other.example/users/bob");
+}
+
+#[test]
+fn local_actor_dto_carries_user_id_and_avatar() {
+    let instance = InstanceIdentity::new("https://md.example");
+    let uid = UserId::from_uuid(uuid::Uuid::new_v4());
+    let mut actor = local_actor(&uid);
+    actor.avatar_url = Some("https://md.example/images/a.webp".into());
+
+    let dto = social_actor_to_dto(actor, &instance);
+
+    assert_eq!(
+        dto.user_id,
+        Some(uid.value()),
+        "local actors must carry user_id for internal links"
+    );
+    assert_eq!(
+        dto.avatar_url.as_deref(),
+        Some("https://md.example/images/a.webp")
+    );
+}
+
+#[test]
+fn remote_actor_dto_has_no_user_id() {
+    let instance = InstanceIdentity::new("https://md.example");
+    let actor = SocialActor {
+        identity: SocialIdentity::Remote {
+            actor_url: "https://other.example/users/bob".into(),
+        },
+        handle: "@bob@other.example".into(),
+        display_name: None,
+        avatar_url: None,
+    };
+    assert_eq!(social_actor_to_dto(actor, &instance).user_id, None);
+}
diff --git a/crates/presentation/src/tests/extractors.rs b/crates/presentation/src/tests/extractors.rs
index 8a2cd575..58ae5c3a 100644
--- a/crates/presentation/src/tests/extractors.rs
+++ b/crates/presentation/src/tests/extractors.rs
@@ -420,7 +420,7 @@ impl domain::ports::RssFeedRenderer for Panic {
         &self,
         _: &[DiaryEntry],
         _: &domain::ports::FeedChannel<'_>,
-    ) -> Result<String, String> {
+    ) -> Result<String, DomainError> {
         panic!()
     }
 }