You are a constitutional council ranking individual git commits for ownership allocation.

Compare these two commits. Decide which contributed more lasting value to the project.

Judge substance, not spectacle:
- Prefer correct, lasting design and real bugfixes over churn, formatting, renames, or generated noise.
- Prefer clarity and necessity over sheer line count. A small precise change can beat a large diffuse one.
- Do not favor a side merely because its patch is longer or noisier.
- Weight what the change does for the project, not the contributor's name.

Return ONLY a JSON object: {"winner": "A" or "B", "ratio": "N:M", "explanation": "..."}
The explanation must cite concrete differences in the patches (1-3 sentences).

Side A — contributor: tommy-mor
Side A — commit message:
[a888d56c] refactor: centralize path identity in slug-types

Move canonicalization and CanonicalItemUrl into types::paths with
GardenItemUrl, ForumThreadUrl, and TildeOntologyPath for JSON hrefs.
Server canonical_path and path_types re-export slug-types; RPC and
validation build hrefs via those types instead of string helpers.

Made-with: Cursor

Side A — unified diff (full patch):
diff --git a/server/src/api/helpers.rs b/server/src/api/helpers.rs
index 9b71491e9f9efc44a2a4beba09be8f64bd2ff2ee..03b3e77911ccd662bec8635345dafe2593cf242e 100644
--- a/server/src/api/helpers.rs
+++ b/server/src/api/helpers.rs
@@ -4,12 +4,12 @@ use axum::{
     Json,
 };
 use sha2::{Digest, Sha256};
+use slug_types::paths::{CanonicalItemUrl, GardenItemUrl};
 use slug_types::*;
 use std::collections::HashMap;
 
 use crate::{
     canonical_path::canonicalize_item,
-    path_types::CanonicalItemUrl,
     ranking::connected_components_from_voted_pairs,
 };
 
@@ -30,64 +30,6 @@ pub fn now_ms() -> i64 {
     t.as_millis() as i64
 }
 
-/// Serialize a canonical item for JSON: absolute URLs stay as-is; bare paths get a `/` prefix.
-pub fn item_path_for_api(item: &str) -> String {
-    if item.starts_with("http://") || item.starts_with("https://") {
-        item.to_string()
-    } else {
-        format!("/{}", item)
-    }
-}
-
-/// Same as [`item_path_for_api`], but for private rooms ontology items are prefixed with
-/// `/r/{short}/{slug}` so the URL matches the web app (`/r/…/~/…` routes).
-pub fn item_path_for_api_in_room(item: &str, room_wire: &str) -> String {
-    let room = room_wire.trim();
-    if room.is_empty() || room == "public" {
-        return item_path_for_api(item);
-    }
-    let Some((short, slug)) = room.split_once('/') else {
-        return item_path_for_api(item);
-    };
-    if short.is_empty() || slug.is_empty() {
-        return item_path_for_api(item);
-    }
-    let Some(c) = CanonicalItemUrl::parse(item) else {
-        return item_path_for_api(item);
-    };
-    let root = CanonicalItemUrl::ontology_root();
-    let item_norm = c.as_str().trim_end_matches('/');
-    let root_norm = root.as_str().trim_end_matches('/');
-    if let Some(tail) = c.tilde_tail() {
-        return if tail.is_empty() {
-            format!("https://slug.social/r/{short}/{slug}/~")
-        } else {
-            format!("https://slug.social/r/{short}/{slug}/~/{}", tail)
-        };
-    }
-    if item_norm == root_norm {
-        return format!("https://slug.social/r/{short}/{slug}/~");
-    }
-    item_path_for_api(item)
-}
-
-/// Absolute thread URL for forum JSON (`/t/…` vs `/r/…/t/…`).
-pub fn forum_thread_web_url(room_wire: &str, thread_tag: &str) -> String {
-    let room = room_wire.trim();
-    let tag = thread_tag.trim().trim_start_matches('#');
-    if room.is_empty() || room == "public" {
-        format!("https://slug.social/t/{tag}")
-    } else if let Some((short, slug)) = room.split_once('/') {
-        if short.is_empty() || slug.is_empty() {
-            format!("https://slug.social/t/{tag}")
-        } else {
-            format!("https://slug.social/r/{short}/{slug}/t/{tag}")
-        }
-    } else {
-        format!("https://slug.social/t/{tag}")
-    }
-}
-
 /// Resolve an item path as a first-class canonical path.
 pub fn resolve_item(item: &str) -> Result<String, String> {
     let canonical = canonicalize_item(item);
@@ -109,14 +51,12 @@ pub fn parse_parent_specs(parent: Option<&String>) -> Vec<String> {
 }
 
 /// Apply offset+limit pagination to the flattened component rankings.
-/// Items are flattened in component order (largest component first), then unranked last.
-/// Returns (components, unranked_items) after the window.
 pub fn paginate_rankings(
     components: Vec<RankComponent>,
-    unranked_items: Vec<String>,
+    unranked_items: Vec<GardenItemUrl>,
     offset: usize,
     limit: Option<usize>,
-) -> (Vec<RankComponent>, Vec<String>) {
+) -> (Vec<RankComponent>, Vec<GardenItemUrl>) {
     let mut remaining_skip = offset;
     let mut remaining_take = limit.unwrap_or(usize::MAX);
     let mut out_components: Vec<RankComponent> = Vec::new();
@@ -141,7 +81,7 @@ pub fn paginate_rankings(
         });
     }
 
-    let out_unranked: Vec<String> = if remaining_take > 0 {
+    let out_unranked: Vec<GardenItemUrl> = if remaining_take > 0 {
         unranked_items
             .into_iter()
             .skip(remaining_skip)
@@ -183,11 +123,9 @@ pub fn is_pair_voted(group: &crate::reducer::GroupState, a: &str, b: &str) -> bo
     group.voted_pairs.contains(&(i, j))
 }
 
-/// Compute graph connectivity stats for a set of items within the ranking group.
 pub fn compute_connectivity_stats(group: &crate::reducer::GroupState, pool: &[String]) -> ConnectivityStats {
     let n = pool.len();
 
-    // Map pool items to global indices (items not yet in the group get no index)
     let global_idxs: Vec<Option<usize>> = pool
         .iter()
         .map(|it| {
@@ -197,7 +135,6 @@ pub fn compute_connectivity_stats(group: &crate::reducer::GroupState, pool: &[St
         .collect();
     let present: Vec<usize> = global_idxs.iter().filter_map(|x| *x).collect();
 
-    // Build local index mapping for items that exist in the ranking group
     let global_to_local: HashMap<usize, usize> = present
         .iter()
         .enumerate()
@@ -213,7 +150,6 @@ pub fn compute_connectivity_stats(group: &crate::reducer::GroupState, pool: &[St
         }),
     );
 
-    // Items not in the ranking group at all are also isolates
     let items_not_in_group = global_idxs.iter().filter(|x| x.is_none()).count();
 
     let num_components = comps.len() + isolates.len() + items_not_in_group;
@@ -237,52 +173,3 @@ pub fn vote_touches_path(a: &str, b: &str, parent_canon: &str) -> bool {
     let under = |item: &str| item == parent_canon || item.starts_with(&format!("{}/", parent_canon));
     under(a) || under(b)
 }
-
-#[cfg(test)]
-mod wire_url_tests {
-    use super::{forum_thread_web_url, item_path_for_api_in_room};
-
-    #[test]
-    fn public_room_unchanged() {
-        let u = "https://slug.social/~/a/b";
-        assert_eq!(item_path_for_api_in_room(u, "public"), u);
-    }
-
-    #[test]
-    fn private_room_prefixes_ontology() {
-        assert_eq!(
-            item_path_for_api_in_room("https://slug.social/~/topic/x", "9ab12cd/my-room"),
-            "https://slug.social/r/9ab12cd/my-room/~/topic/x"
-        );
-    }
-
-    #[test]
-    fn private_room_ontology_root() {
-        assert_eq!(
-            item_path_for_api_in_room("https://slug.social/~", "9ab12cd/my-room"),
-            "https://slug.social/r/9ab12cd/my-room/~"
-        );
-        assert_eq!(
-            item_path_for_api_in_room("https://slug.social/~/", "9ab12cd/my-room"),
-            "https://slug.social/r/9ab12cd/my-room/~"
-        );
-    }
-
-    #[test]
-    fn external_url_untouched_in_private_room() {
-        let u = "https://example.com/z";
-        assert_eq!(item_path_for_api_in_room(u, "9ab12cd/my-room"), u);
-    }
-
-    #[test]
-    fn forum_web_public_vs_room() {
-        assert_eq!(
-            forum_thread_web_url("public", "debate"),
-            "https://slug.social/t/debate"
-        );
-        assert_eq!(
-            forum_thread_web_url("9ab12cd/my-room", "#debate"),
-            "https://slug.social/r/9ab12cd/my-room/t/debate"
-        );
-    }
-}
diff --git a/server/src/api/mod.rs b/server/src/api/mod.rs
index 042aa248305f9362a3be78f9eea2a5abf6ba707a..cf22cb0129366c3aed031bc86f3197a4321cb806 100644
--- a/server/src/api/mod.rs
+++ b/server/src/api/mod.rs
@@ -24,8 +24,7 @@ pub use auth::{
 
 pub use helpers::{
     api_error, compute_connectivity_stats, is_pair_voted, now_ms, paginate_rankings,
-    parse_parent_specs, pick_random_distinct, sha256_hex, resolve_item, vote_touches_path,
-    item_path_for_api,
+    parse_parent_specs, pick_random_distinct, resolve_item, sha256_hex, vote_touches_path,
 };
 
 pub use rpc::handle_rpc_batch;
diff --git a/server/src/api/rpc.rs b/server/src/api/rpc.rs
index 5b91f5836625eedbb1cd9423168046e3fb576c17..5f7d50188f1381267402f2e57e671234ef5db2fd 100644
--- a/server/src/api/rpc.rs
+++ b/server/src/api/rpc.rs
@@ -8,6 +8,7 @@ use axum::{
     Json,
 };
 use rand::seq::SliceRandom;
+use slug_types::paths::{ForumThreadUrl, GardenItemUrl, TildeOntologyPath};
 use slug_types::*;
 
 use crate::{
@@ -27,9 +28,8 @@ use crate::{
 
 use super::auth::verify_bearer_principal;
 use super::helpers::{
-    compute_connectivity_stats, forum_thread_web_url, is_pair_voted, item_path_for_api,
-    item_path_for_api_in_room, now_ms, paginate_rankings, parse_parent_specs, pick_random_distinct,
-    resolve_item, vote_touches_path,
+    compute_connectivity_stats, is_pair_voted, now_ms, paginate_rankings, parse_parent_specs,
+    pick_random_distinct, resolve_item, vote_touches_path,
 };
 use super::validate::{normalize_room_and_thread, validate_ingest_document};
 
@@ -184,7 +184,7 @@ fn compute_scope_rank_changes(
         };
         if changed {
             changes.push(RankChange {
-                item: item_path_for_api_in_room(&item, room_wire),
+                item: GardenItemUrl::from_storage_str(&item, room_wire),
                 before: b,
                 after: a,
             });
@@ -206,7 +206,7 @@ fn compute_scope_rank_changes(
         parent: if parent.is_empty() {
             "/".to_string()
         } else {
-            item_path_for_api_in_room(parent, room_wire)
+            GardenItemUrl::from_storage_str(parent, room_wire).into_inner()
         },
         changes,
     })
@@ -302,7 +302,7 @@ fn build_rank_response_for_content(
                     .ranked
                     .into_iter()
                     .map(|r| RankRow {
-                        item: item_path_for_api_in_room(r.item.as_str(), room_wire),
+                        item: GardenItemUrl::from_stored(&r.item, room_wire),
                         percent: if want_percent {
                             Some((r.score / max_score) * 100.0)
                         } else {
@@ -315,10 +315,10 @@ fn build_rank_response_for_content(
         })
         .collect();
 
-    let prefixed_unranked: Vec<String> = rankings
+    let prefixed_unranked: Vec<GardenItemUrl> = rankings
         .unranked_items
         .into_iter()
-        .map(|s| item_path_for_api_in_room(s.as_str(), room_wire))
+        .map(|s| GardenItemUrl::from_stored(&s, room_wire))
         .collect();
 
     let (components, unranked_items) = if offset > 0 || limit.is_some() {
@@ -537,13 +537,13 @@ async fn rpc_post(
         (
             "npx slugsocial public garden pair".to_string(),
             "npx slugsocial public garden rank".to_string(),
-            forum_thread_web_url("public", &thread_id),
+            ForumThreadUrl::from_room_tag("public", &thread_id),
         )
     } else {
         (
             format!("npx slugsocial private {room_key} garden pair"),
             format!("npx slugsocial private {room_key} garden rank"),
-            forum_thread_web_url(&room_key, &thread_id),
+            ForumThreadUrl::from_room_tag(&room_key, &thread_id),
         )
     };
 
@@ -664,7 +664,7 @@ async fn rpc_check(
                         .ranked
                         .into_iter()
                         .map(|r| RankRow {
-                            item: item_path_for_api_in_room(r.item.as_str(), &room_key),
+                            item: GardenItemUrl::from_stored(&r.item, &room_key),
                             score: r.score,
                             percent: None,
                         })
@@ -672,12 +672,12 @@ async fn rpc_check(
                 })
                 .collect();
             CheckScopeRanking {
-                parent: item_path_for_api_in_room(parent.as_str(), &room_key),
+                parent: GardenItemUrl::from_stored(parent, &room_key).into_inner(),
                 components,
                 unranked_items: scoped
                     .unranked_items
                     .into_iter()
-                    .map(|it| item_path_for_api_in_room(it.as_str(), &room_key))
+                    .map(|it| GardenItemUrl::from_stored(&it, &room_key))
                     .collect(),
             }
         })
@@ -687,13 +687,13 @@ async fn rpc_check(
         vec![
             "npx slugsocial public forum post <TAG> --delegate <uuid:rig:model>".to_string(),
             "npx slugsocial public forum list".to_string(),
-            forum_thread_web_url("public", &thread_id),
+            ForumThreadUrl::from_room_tag("public", &thread_id).into_inner(),
         ]
     } else {
         vec![
             format!("npx slugsocial private {room_key} forum post <TAG> --delegate <uuid:rig:model>"),
             format!("npx slugsocial private {room_key} forum list"),
-            forum_thread_web_url(&room_key, &thread_id),
+            ForumThreadUrl::from_room_tag(&room_key, &thread_id).into_inner(),
         ]
     };
 
@@ -717,7 +717,7 @@ fn rpc_list_forum_threads(reduced: &ReducerState, room: &str) -> ThreadsResponse
         .map(|((_, tag), ts)| ThreadSummary {
             thread: format!("#{tag}"),
             last_activity_ts: ts.last_activity_ts,
-            web: forum_thread_web_url(room, tag),
+            web: ForumThreadUrl::from_room_tag(room, tag),
         })
         .collect();
     out.sort_by(|a, b| b.last_activity_ts.cmp(&a.last_activity_ts));
@@ -885,7 +885,7 @@ fn rpc_search(reduced: &ReducerState, q: &str, limit: usize, principal: Option<&
         }
         if score > 0 {
             scored_items.push((score, SearchItemHit {
-                path: item_path_for_api(item.as_str()),
+                path: GardenItemUrl::from_storage_str(item.as_str(), "public"),
                 body: content.item_bodies.get(item).map(|b| snippet_around(b, &words, 120)),
             }));
         }
@@ -1058,8 +1058,8 @@ async fn rpc_get_pair(state: &AppState, room: String, parent_path: String) -> Re
         .collect();
     let cs = compute_connectivity_stats(&content.ranking_group, &pool);
     Ok(RpcResult::Pair(PairResponse {
-        left: item_path_for_api_in_room(&left, &room),
-        right: item_path_for_api_in_room(&right, &room),
+        left: GardenItemUrl::from_storage_str(&left, &room),
+        right: GardenItemUrl::from_storage_str(&right, &room),
         left_body: lb,
         right_body: rb,
         threads: th,
@@ -1137,7 +1137,7 @@ pub async fn handle_rpc_batch(
                 if !content.items.contains(&item) {
                     line_err(
                         "item not found",
-                        Some(format!("{} does not exist", item_path_for_api_in_room(&item_str, &room))),
+                        Some(format!("{} does not exist", GardenItemUrl::from_storage_str(&item_str, &room))),
                     )
                 } else {
                     const MAX_ITEM_BODY: usize = 10_000;
@@ -1160,7 +1160,7 @@ pub async fn handle_rpc_batch(
                         .map(|s| s.iter().cloned().collect())
                         .unwrap_or_default();
                     line_ok(RpcResult::GardenItem(ItemResponse {
-                        item: item_path_for_api_in_room(&item_str, &room),
+                        item: GardenItemUrl::from_storage_str(&item_str, &room),
                         body,
                         truncated,
                         body_len,
@@ -1554,7 +1554,7 @@ pub async fn handle_rpc_batch(
                     for r in items {
                         let pct = want_percent.then(|| ((r.score - bot) / range * 100.0).clamp(0.0, 100.0));
                         ranked.push(RankRow {
-                            item: item_path_for_api_in_room(r.item.as_str(), &room),
+                            item: GardenItemUrl::from_storage_str(r.item.as_str(), &room),
                             score: r.score,
                             percent: pct,
                         });
@@ -1574,7 +1574,7 @@ pub async fn handle_rpc_batch(
                 let page: Vec<RankRow> = ranked
                     .into_iter()
                     .chain(unranked.into_iter().map(|it| RankRow {
-                        item: item_path_for_api_in_room(&it, &room),
+                        item: GardenItemUrl::from_storage_str(&it, &room),
                         score: 0.0,
                         percent: want_percent.then_some(0.0),
                     }))
@@ -1618,7 +1618,7 @@ pub async fn handle_rpc_batch(
                 if !content.items.contains(&item) {
                     line_err(
                         "item not found",
-                        Some(format!("{} does not exist", item_path_for_api_in_room(&item_str, &room))),
+                        Some(format!("{} does not exist", GardenItemUrl::from_storage_str(&item_str, &room))),
                     )
                 } else {
                     let votes: Vec<VoteRow> = content
@@ -1629,8 +1629,8 @@ pub async fn handle_rpc_batch(
                                 .take(limit)
                                 .map(|v| VoteRow {
                                     ts: v.ts,
-                                    a: item_path_for_api_in_room(v.a.as_str(), &room),
-                                    b: item_path_for_api_in_room(v.b.as_str(), &room),
+                                    a: GardenItemUrl::from_stored(&v.a, &room),
+                                    b: GardenItemUrl::from_stored(&v.b, &room),
                                     ratio: format!("{}:{}", v.ratio_left, v.ratio_right),
                                     actor: Some(v.principal.clone()),
                                     body: v.body.clone(),
@@ -1640,7 +1640,7 @@ pub async fn handle_rpc_batch(
                         })
                         .unwrap_or_default();
                     line_ok(RpcResult::Matchup(MatchupResponse {
-                        item: item_path_for_api_in_room(&item_str, &room),
+                        item: GardenItemUrl::from_storage_str(&item_str, &room),
                         votes,
                     }))
                 }
@@ -1667,8 +1667,8 @@ pub async fn handle_rpc_batch(
                                     if a == item_str || b == item_str {
                                         Some(VoteRow {
                                             ts: e.ts,
-                                            a: item_path_for_api_in_room(&a, &room),
-                                            b: item_path_for_api_in_room(&b, &room),
+                                            a: GardenItemUrl::from_storage_str(&a, &room),
+                                            b: GardenItemUrl::from_storage_str(&b, &room),
                                             ratio: format!("{}:{}", ratio_left, ratio_right),
                                             actor: reduced.ingests_by_id.get(&e.post_id).map(|ing| ing.principal.clone()),
                                             body: explanation,
@@ -1704,7 +1704,7 @@ pub async fn handle_rpc_batch(
                     }
                 }).collect();
                 line_ok(RpcResult::RankHistory(RankHistoryResponse {
-                    item: item_path_for_api_in_room(&item_str, &room),
+                    item: GardenItemUrl::from_storage_str(&item_str, &room),
                     history,
                 }))
                 }
@@ -1716,17 +1716,13 @@ pub async fn handle_rpc_batch(
                 } else {
                 let content = content_for_room(&reduced, &room);
                 let parents: HashSet<&str> = content.item_children.keys().map(|s| s.as_str()).collect();
-                let mut paths: Vec<String> = content
+                let mut paths: Vec<GardenItemUrl> = content
                     .items
                     .iter()
                     .filter(|p| !parents.contains(p.as_str()))
-                    .map(|p| p.as_str().to_string())
-                    .collect();
-                paths.sort();
-                let paths: Vec<String> = paths
-                    .into_iter()
-                    .map(|p| item_path_for_api_in_room(&p, &room))
+                    .map(|p| GardenItemUrl::from_stored(p, &room))
                     .collect();
+                paths.sort_by(|a, b| a.as_str().cmp(b.as_str()));
                 line_ok(RpcResult::Leaves(LeavesResponse { paths }))
                 }
             },
@@ -1743,24 +1739,13 @@ pub async fn handle_rpc_batch(
                         let mut v: Vec<PathSummary> = roots.iter()
                             .map(|path| {
                                 let children = content.item_children.get(path.as_str()).map(|s| s.len()).unwrap_or(0);
-                                let path_label = CanonicalItemUrl::parse(path.as_str())
-                                    .and_then(|c| {
-                                        c.tilde_tail().map(|t| {
-                                            if t.is_empty() {
-                                                "~/".to_string()
-                                            } else {
-                                                format!("~/{}", t)
-                                            }
-                                        })
-                                    })
-                                    .unwrap_or_else(|| path.to_string());
                                 PathSummary {
-                                    path: path_label,
+                                    path: TildeOntologyPath::from_stored(path),
                                     children,
-                                    web: item_path_for_api_in_room(path.as_str(), &room),
+                                    web: GardenItemUrl::from_stored(path, &room),
                                 }
                             }).collect();
-                        v.sort_by(|a, b| a.path.cmp(&b.path));
+                        v.sort_by(|a, b| a.path.as_str().cmp(b.path.as_str()));
                         v
                     })
                     .unwrap_or_default();
@@ -1790,8 +1775,8 @@ pub async fn handle_rpc_batch(
                     .take(limit)
                     .map(|v| VoteRow {
                         ts: v.ts,
-                        a: item_path_for_api_in_room(v.a.as_str(), &room),
-                        b: item_path_for_api_in_room(v.b.as_str(), &room),
+                        a: GardenItemUrl::from_stored(&v.a, &room),
+                        b: GardenItemUrl::from_stored(&v.b, &room),
                         ratio: format!("{}:{}", v.ratio_left, v.ratio_right),
                         actor: Some(v.principal.clone()),
                         body: v.body.clone(),
diff --git a/server/src/api/validate.rs b/server/src/api/validate.rs
index 27150577982f52cbd6d11bb93654dc3d4cf75cc5..a51c783ee9785569b5a44c0b1572471fe00d174b 100644
--- a/server/src/api/validate.rs
+++ b/server/src/api/validate.rs
@@ -7,8 +7,9 @@ use crate::{
     path_types::CanonicalItemUrl,
     reducer::{ReducerState, ScopeId},
 };
+use slug_types::paths::GardenItemUrl;
 
-use super::helpers::{item_path_for_api, resolve_item};
+use super::helpers::resolve_item;
 
 #[derive(Debug)]
 pub struct ValidatedIngest {
@@ -22,6 +23,10 @@ pub fn validate_ingest_document(
     text: &str,
     scope: &ScopeId,
 ) -> Result<ValidatedIngest, (StatusCode, String, Option<String>)> {
+    let room_wire = match scope {
+        ScopeId::Public => "public",
+        ScopeId::Room(r) => r.as_str(),
+    };
     let public_content = reduced.public();
     let scoped_content = match scope {
         ScopeId::Public => None,
@@ -61,14 +66,14 @@ pub fn validate_ingest_document(
                 let Some(body_text) = body else {
                     return Err((
                         StatusCode::BAD_REQUEST,
-                        format!("item missing body: {}", item_path_for_api(&item)),
+                        format!("item missing body: {}", GardenItemUrl::from_storage_str(&item, room_wire)),
                         Some("items must be declared with bodies, e.g. `~/path/item { ... }`".to_string()),
                     ));
                 };
                 if body_text.trim().is_empty() {
                     return Err((
                         StatusCode::BAD_REQUEST,
-                        format!("item body is empty: {}", item_path_for_api(&item)),
+                        format!("item body is empty: {}", GardenItemUrl::from_storage_str(&item, room_wire)),
                         Some("write at least one sentence inside `{ ... }`".to_string()),
                     ));
                 }
@@ -101,7 +106,7 @@ pub fn validate_ingest_document(
                         let key = CanonicalItemUrl((*it).clone());
                         !defined_in_doc.contains(*it) && !item_exists(&key)
                     })
-                    .map(|it| item_path_for_api(it))
+                    .map(|it| GardenItemUrl::from_storage_str(it, room_wire).into_inner())
                     .collect();
                 if !missing.is_empty() {
                     return Err((
@@ -119,7 +124,7 @@ pub fn validate_ingest_document(
                         let key = CanonicalItemUrl((*it).clone());
                         !defined_in_doc.contains(*it) && !body_exists(&key)
                     })
-                    .map(|it| item_path_for_api(it))
+                    .map(|it| GardenItemUrl::from_storage_str(it, room_wire).into_inner())
                     .collect();
                 if !missing_body.is_empty() {
                     return Err((
diff --git a/server/src/canonical_path.rs b/server/src/canonical_path.rs
index 5c0febe883d8b3978a25896ed0d71df8509a8717..8a1998025121838b0867f8c5ddbd28aea41a23d2 100644
--- a/server/src/canonical_path.rs
+++ b/server/src/canonical_path.rs
@@ -1,92 +1,3 @@
-//! Normalization for thread tags and ontology item URLs (DSL ↔ stored canonical form).
-//! Not event types — see `events` and `path_types`.
+//! Re-exports — implementations live in `slug-types` (`paths` module).
 
-/// Thread / public tag: stored without leading `#`, lowercase.
-pub fn canonicalize_tag(input: &str) -> String {
-    input.trim().trim_start_matches('#').to_lowercase()
-}
-
-/// Ontology item reference → canonical absolute URL on the slug host.
-pub fn canonicalize_item(input: &str) -> String {
-    let s = input.trim();
-    if s.is_empty() {
-        return String::new();
-    }
-
-    if let Some(rest) = s.strip_prefix("https://") {
-        let (host, tail) = rest.split_once('/').map_or((rest, ""), |(h, t)| (h, t));
-        let host = host.trim().to_lowercase();
-        if tail.is_empty() {
-            return format!("https://{}", host);
-        } else {
-            return format!("https://{}/{}", host, tail);
-        }
-    }
-    if let Some(rest) = s.strip_prefix("http://") {
-        let (host, tail) = rest.split_once('/').map_or((rest, ""), |(h, t)| (h, t));
-        let host = host.trim().to_lowercase();
-        if tail.is_empty() {
-            return format!("http://{}", host);
-        } else {
-            return format!("http://{}/{}", host, tail);
-        }
-    }
-
-    let is_tilde = s.starts_with("~/");
-    let rest = s.strip_prefix("~/").or_else(|| s.strip_prefix("/")).unwrap_or(s);
-
-    let tail = rest
-        .split('/')
-        .filter_map(|seg| {
-            let t = seg.trim();
-            if t.is_empty() {
-                None
-            } else {
-                Some(t.to_lowercase())
-            }
-        })
-        .collect::<Vec<_>>()
-        .join("/");
-
-    if is_tilde {
-        format!("https://slug.social/~/{}", tail)
-    } else if tail.is_empty() {
-        "https://slug.social".to_string()
-    } else {
-        format!("https://slug.social/{}", tail)
-    }
-}
-
-pub fn item_path_segments(input: &str) -> Vec<String> {
-    let canonical = canonicalize_item(input);
-    if canonical.is_empty() {
-        return vec![];
-    }
-
-    if let Some(rest) = canonical.strip_prefix("https://") {
-        let (host, tail) = rest.split_once('/').map_or((rest, ""), |(h, t)| (h, t));
-        let mut out = vec![format!("https://{}", host)];
-        out.extend(tail.split('/').filter(|s| !s.is_empty()).map(|s| s.to_string()));
-        return out;
-    }
-    if let Some(rest) = canonical.strip_prefix("http://") {
-        let (host, tail) = rest.split_once('/').map_or((rest, ""), |(h, t)| (h, t));
-        let mut out = vec![format!("http://{}", host)];
-        out.extend(tail.split('/').filter(|s| !s.is_empty()).map(|s| s.to_string()));
-        return out;
-    }
-
-    canonical
-        .split('/')
-        .filter(|s| !s.is_empty())
-        .map(|s| s.to_string())
-        .collect()
-}
-
-pub fn item_parent_path(input: &str) -> Option<String> {
-    let segs = item_path_segments(input);
-    if segs.len() <= 1 {
-        return None;
-    }
-    Some(segs[..segs.len() - 1].join("/"))
-}
+pub use slug_types::paths::{canonicalize_item, canonicalize_tag, item_parent_path, item_path_segments};
diff --git a/server/src/html/forum.rs b/server/src/html/forum.rs
index ab7970feca47a4431ddc19dab2c8186180b78413..f789e347dc136f8ffd356f4492f0bd76cea04bf0 100644
--- a/server/src/html/forum.rs
+++ b/server/src/html/forum.rs
@@ -697,7 +697,7 @@ async fn thread_view_inner(
     let offset = q.offset.unwrap_or(0);
     let page_ids: Vec<String> = all_ids.into_iter().skip(offset).take(PAGE_SIZE).collect();
 
-    let (display_ingests, subtitle) = {
+    let (display_ingests, _subtitle) = {
         let reduced = state.reduced.read().await;
         let ingests = page_ids
             .iter()
diff --git a/server/src/path_types.rs b/server/src/path_types.rs
index cad58cac7da948f92d6ea2a5587d917ab21d57ea..4c8075bbd488f1b9a5eda9e03ced83f6238c6d5e 100644
--- a/server/src/path_types.rs
+++ b/server/src/path_types.rs
@@ -1,260 +1,3 @@
-//! Path representation types.
-//!
-//! The codebase currently treats item identifiers as strings in a few different
-//! encodings:
-//! - user/DSL input like `~/a/b`
-//! - canonical item URLs like `https://slug.social/~/a/b`
-//! - relative paths within a rooted tree view (e.g. `llms/openai` under a root)
-//!
-//! This module adds lightweight newtypes so code can be explicit about what it
-//! expects without changing core storage formats.
-//!
-//! **Storage vs wire:** [`CanonicalItemUrl`] values are shared across scopes
-//! (`https://slug.social/~/…`); which [`crate::reducer::ContentState`] they live in
-//! is determined by scope, not by embedding the room id in the string. For JSON/RPC
-//! and browser links in a private room, use [`crate::api::helpers::item_path_for_api_in_room`]
-//! so ontology items become `https://slug.social/r/{short}/{slug}/~/…`.
+//! Re-exports — implementations live in `slug-types` (`paths` module).
 
-use std::borrow::Borrow;
-use std::fmt;
-
-use serde::{Deserialize, Serialize};
-
-use crate::canonical_path::canonicalize_item;
-
-/// Canonical item identifier as produced by `canonical_path::canonicalize_item`.
-///
-/// In practice this is usually:
-/// - `https://slug.social/~/...` for ontology items, or
-/// - `https://...` / `http://...` for URL items.
-#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
-pub struct CanonicalItemUrl(pub String);
-
-impl CanonicalItemUrl {
-    pub fn parse(input: &str) -> Option<Self> {
-        let c = canonicalize_item(input);
-        if c.is_empty() {
-            None
-        } else {
-            Some(Self(c))
-        }
-    }
-
-    pub fn as_str(&self) -> &str {
-        &self.0
-    }
-
-    /// Returns the `~/...` tail for ontology items (`https://slug.social/~/...`).
-    pub fn tilde_tail(&self) -> Option<&str> {
-        self.0.strip_prefix("https://slug.social/~/")
-    }
-
-    /// Returns the final non-empty `/`-separated segment of the path.
-    ///
-    /// `https://slug.social/~/a/b/c` → `"c"`
-    /// `https://slug.social/~/a`     → `"a"`
-    pub fn last_segment(&self) -> &str {
-        self.0
-            .rsplit('/')
-            .find(|s| !s.is_empty())
-            .unwrap_or(self.0.as_str())
-    }
-
-    /// The ontology root key as stored in `item_children`: `"https://slug.social/~"`.
-    /// Use this (not `parse("~/")`) when looking up top-level children.
-    pub fn ontology_root() -> Self {
-        Self("https://slug.social/~".to_string())
-    }
-
-    /// Returns the parent of this canonical item URL by stripping the last
-    /// path segment, or `None` if there is no parent (already at root).
-    ///
-    /// `https://slug.social/~/a/b/c` → `Some("https://slug.social/~/a/b")`
-    /// `https://slug.social/~/a`     → `Some("https://slug.social/~")`
-    /// `https://slug.social/~/`      → `None`  (tilde root)
-    pub fn parent(&self) -> Option<Self> {
-        // tilde_tail() is None for non-ontology URLs and "" for the root ~/
-        if self.tilde_tail().map(|t| t.is_empty()).unwrap_or(true) {
-            return None;
-        }
-        // Strip everything from the last '/' onwards.
-        let last_slash = self.0.rfind('/')?;
-        let parent_str = &self.0[..last_slash];
-        if parent_str.is_empty() {
-            None
-        } else {
-            Some(Self(parent_str.to_string()))
-        }
-    }
-
-    /// Segments of an ontology path suitable for breadcrumb rendering.
-    /// Strips the `https://slug.social` prefix and returns the `~/…` parts.
-    ///
-    /// `https://slug.social/~/a/b` → `["~", "a", "b"]`
-    /// `https://slug.social/~/`    → `["~"]`
-    pub fn tilde_segments(&self) -> Vec<&str> {
-        match self.tilde_tail() {
-            Some(tail) if !tail.is_empty() => {
-                std::iter::once("~")
-                    .chain(tail.split('/').filter(|s| !s.is_empty()))
-                    .collect()
-            }
-            Some(_) => vec!["~"],
-            None => vec![],
-        }
-    }
-}
-
-impl fmt::Display for CanonicalItemUrl {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.0.fmt(f)
-    }
-}
-
-/// Allow `HashMap<CanonicalItemUrl, _>` to be searched by `&str`.
-impl Borrow<str> for CanonicalItemUrl {
-    fn borrow(&self) -> &str {
-        &self.0
-    }
-}
-
-impl PartialEq<str> for CanonicalItemUrl {
-    fn eq(&self, other: &str) -> bool {
-        self.0 == other
-    }
-}
-
-impl PartialEq<&str> for CanonicalItemUrl {
-    fn eq(&self, other: &&str) -> bool {
-        self.0 == *other
-    }
-}
-
-impl PartialEq<String> for CanonicalItemUrl {
-    fn eq(&self, other: &String) -> bool {
-        &self.0 == other
-    }
-}
-
-/// A `~/...` input path (as used in the DSL and UX).
-///
-/// This is not canonicalized; it is a presentation/input form.
-#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
-pub struct TildePath(pub String);
-
-impl TildePath {
-    pub fn new(input: &str) -> Option<Self> {
-        let s = input.trim();
-        if s.starts_with("~/") && s.len() > 2 {
-            Some(Self(s.to_string()))
-        } else if s == "~/" {
-            Some(Self("~/".to_string()))
-        } else {
-            None
-        }
-    }
-
-    pub fn as_str(&self) -> &str {
-        &self.0
-    }
-
-    pub fn canonicalize(&self) -> Option<CanonicalItemUrl> {
-        CanonicalItemUrl::parse(&self.0)
-    }
-}
-
-impl fmt::Display for TildePath {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.0.fmt(f)
-    }
-}
-
-/// A path relative to a chosen root in a tree UI.
-///
-/// This is intended for compact state encodings (blobs). It must be joined to a
-/// root `CanonicalItemUrl` (typically an ontology root) to become a full item.
-#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
-pub struct RelativePath(pub String);
-
-impl RelativePath {
-    pub fn new(input: &str) -> Option<Self> {
-        let s = input.trim().trim_matches('/');
-        if s.is_empty() {
-            Some(Self(String::new()))
-        } else {
-            // Keep this permissive: the DSL parser is the main gatekeeper.
-            Some(Self(s.to_string()))
-        }
-    }
-
-    pub fn as_str(&self) -> &str {
-        &self.0
-    }
-
-    /// Join this relative path under a canonical ontology root
-    /// (`https://slug.social/~/...`) to form a canonical item URL.
-    pub fn join_under_ontology_root(&self, root: &CanonicalItemUrl) -> Option<CanonicalItemUrl> {
-        let base = root.tilde_tail()?;
-        // base is the tail after https://slug.social/~/, e.g. "models" or "models/llms"
-        let joined = if base.is_empty() {
-            if self.0.is_empty() {
-                "~/".to_string()
-            } else {
-                format!("~/{}", self.0)
-            }
-        } else if self.0.is_empty() {
-            format!("~/{}", base)
-        } else {
-            format!("~/{}/{}", base.trim_end_matches('/'), self.0)
-        };
-        CanonicalItemUrl::parse(&joined)
-    }
-}
-
-impl fmt::Display for RelativePath {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.0.fmt(f)
-    }
-}
-
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn canonical_parent_deep() {
-        let c = CanonicalItemUrl::parse("~/a/b/c").unwrap();
-        assert_eq!(c.parent().unwrap().as_str(), "https://slug.social/~/a/b");
-    }
-
-    #[test]
-    fn canonical_parent_one_level() {
-        let c = CanonicalItemUrl::parse("~/a").unwrap();
-        assert_eq!(c.parent().unwrap().as_str(), "https://slug.social/~");
-    }
-
-    #[test]
-    fn canonical_parent_root_is_none() {
-        let root = CanonicalItemUrl::parse("~/").unwrap();
-        assert!(root.parent().is_none());
-    }
-
-    #[test]
-    fn tilde_segments_deep() {
-        let c = CanonicalItemUrl::parse("~/a/b").unwrap();
-        assert_eq!(c.tilde_segments(), vec!["~", "a", "b"]);
-    }
-
-    #[test]
-    fn tilde_segments_root() {
-        let c = CanonicalItemUrl::parse("~/").unwrap();
-        assert_eq!(c.tilde_segments(), vec!["~"]);
-    }
-
-    #[test]
-    fn tilde_segments_non_ontology_is_empty() {
-        let c = CanonicalItemUrl::parse("https://example.com/foo").unwrap();
-        assert_eq!(c.tilde_segments(), Vec::<&str>::new());
-    }
-}
+pub use slug_types::paths::{CanonicalItemUrl, RelativePath, TildePath};
diff --git a/types/src/lib.rs b/types/src/lib.rs
index c1cde3b783d03b02783385b5f07659fb112aae3e..5fc867bf2af84c2ca63fa1cdd03413110ad784a3 100644
--- a/types/src/lib.rs
+++ b/types/src/lib.rs
@@ -1,7 +1,13 @@
 use serde::{Deserialize, Serialize};
 
+pub mod paths;
 pub mod timeago;
 
+pub use paths::{
+    canonicalize_item, canonicalize_tag, item_parent_path, item_path_segments, CanonicalItemUrl,
+    ForumThreadUrl, GardenItemUrl, RelativePath, TildeOntologyPath, TildePath,
+};
+
 #[derive(Debug, Serialize, Deserialize)]
 pub struct ApiError {
     pub ok: bool,
@@ -12,7 +18,7 @@ pub struct ApiError {
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct RankRow {
-    pub item: String,
+    pub item: GardenItemUrl,
     pub score: f64,
     /// Normalized score as a percentage of the top item (0–100). Present when ?percent=true.
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -43,7 +49,7 @@ pub struct RankComponent {
 #[derive(Debug, Serialize, Deserialize)]
 pub struct RankResponse {
     pub components: Vec<RankComponent>,
-    pub unranked_items: Vec<String>,
+    pub unranked_items: Vec<GardenItemUrl>,
 }
 
 /// Graph connectivity stats for a scope, returned with pair suggestions.
@@ -63,8 +69,8 @@ pub struct ConnectivityStats {
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct PairResponse {
-    pub left: String,
-    pub right: String,
+    pub left: GardenItemUrl,
+    pub right: GardenItemUrl,
     pub left_body: Option<String>,
     pub right_body: Option<String>,
     /// Thread tags that discuss either item (connective tissue to forum).
@@ -79,7 +85,7 @@ pub struct PairResponse {
 pub struct NextMoves {
     pub pair: String,
     pub rank: String,
-    pub web: String,
+    pub web: ForumThreadUrl,
 }
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -90,14 +96,14 @@ pub struct PathsResponse {
 /// Leaf items only (no children). For search / "full path list" — does not scale, works for now.
 #[derive(Debug, Serialize, Deserialize)]
 pub struct LeavesResponse {
-    pub paths: Vec<String>,
+    pub paths: Vec<GardenItemUrl>,
 }
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct PathSummary {
-    pub path: String,
+    pub path: TildeOntologyPath,
     pub children: usize,
-    pub web: String,
+    pub web: GardenItemUrl,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -109,7 +115,7 @@ pub struct ThreadsResponse {
 pub struct ThreadSummary {
     pub thread: String,
     pub last_activity_ts: i64,
-    pub web: String,
+    pub web: ForumThreadUrl,
 }
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -178,7 +184,7 @@ pub struct IngestRow {
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct ItemResponse {
-    pub item: String,
+    pub item: GardenItemUrl,
     pub body: Option<String>,
     /// True when the body was truncated due to size. Fetch with `?full=true` for the complete body.
     #[serde(default, skip_serializing_if = "std::ops::Not::not")]
@@ -201,15 +207,15 @@ pub struct RecentVotesResponse {
 /// Vote history for one item (matchup: wins/losses + thread per vote).
 #[derive(Debug, Serialize, Deserialize)]
 pub struct MatchupResponse {
-    pub item: String,
+    pub item: GardenItemUrl,
     pub votes: Vec<VoteRow>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct VoteRow {
     pub ts: i64,
-    pub a: String,
-    pub b: String,
+    pub a: GardenItemUrl,
+    pub b: GardenItemUrl,
     pub ratio: String,
     /// Principal username when present (stored form, no `@`).
     pub actor: Option<String>,
@@ -510,7 +516,7 @@ pub struct RankPosition {
 /// How one item's rank changed after a vote.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct RankChange {
-    pub item: String,
+    pub item: GardenItemUrl,
     /// Position before the vote. None = was unranked (no voted connections in this scope).
     pub before: Option<RankPosition>,
     /// Position after the vote. None = became unranked (e.g. component split, unlikely).
@@ -544,7 +550,7 @@ pub struct CheckScopeRanking {
     /// Parent scope path (e.g. "/models" or "/" for root).
     pub parent: String,
     pub components: Vec<RankComponent>,
-    pub unranked_items: Vec<String>,
+    pub unranked_items: Vec<GardenItemUrl>,
 }
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -567,7 +573,7 @@ pub struct SearchResponse {
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct SearchItemHit {
-    pub path: String,
+    pub path: GardenItemUrl,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub body: Option<String>,
 }
@@ -614,7 +620,7 @@ pub struct RankHistoryRow {
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct RankHistoryResponse {
-    pub item: String,
+    pub item: GardenItemUrl,
     pub history: Vec<RankHistoryRow>,
 }
 
diff --git a/types/src/paths.rs b/types/src/paths.rs
new file mode 100644
index 0000000000000000000000000000000000000000..2950a7502255927583fbacdfd2adb700f0b0c221
--- /dev/null
+++ b/types/src/paths.rs
@@ -0,0 +1,498 @@
+//! Canonical paths, storage ids, and JSON href newtypes. All normalization and
+//! room-aware URL rules for items live here.
+
+use std::borrow::Borrow;
+use std::fmt;
+
+use serde::{Deserialize, Serialize};
+
+// ---------------------------------------------------------------------------
+// Normalization (moved from server `canonical_path`)
+// ---------------------------------------------------------------------------
+
+/// Thread / public tag: stored without leading `#`, lowercase.
+pub fn canonicalize_tag(input: &str) -> String {
+    input.trim().trim_start_matches('#').to_lowercase()
+}
+
+/// Ontology item reference → canonical absolute URL on the slug host.
+pub fn canonicalize_item(input: &str) -> String {
+    let s = input.trim();
+    if s.is_empty() {
+        return String::new();
+    }
+
+    if let Some(rest) = s.strip_prefix("https://") {
+        let (host, tail) = rest.split_once('/').map_or((rest, ""), |(h, t)| (h, t));
+        let host = host.trim().to_lowercase();
+        if tail.is_empty() {
+            return format!("https://{}", host);
+        } else {
+            return format!("https://{}/{}", host, tail);
+        }
+    }
+    if let Some(rest) = s.strip_prefix("http://") {
+        let (host, tail) = rest.split_once('/').map_or((rest, ""), |(h, t)| (h, t));
+        let host = host.trim().to_lowercase();
+        if tail.is_empty() {
+            return format!("http://{}", host);
+        } else {
+            return format!("http://{}/{}", host, tail);
+        }
+    }
+
+    let is_tilde = s.starts_with("~/");
+    let rest = s.strip_prefix("~/").or_else(|| s.strip_prefix("/")).unwrap_or(s);
+
+    let tail = rest
+        .split('/')
+        .filter_map(|seg| {
+            let t = seg.trim();
+            if t.is_empty() {
+                None
+            } else {
+                Some(t.to_lowercase())
+            }
+        })
+        .collect::<Vec<_>>()
+        .join("/");
+
+    if is_tilde {
+        format!("https://slug.social/~/{}", tail)
+    } else if tail.is_empty() {
+        "https://slug.social".to_string()
+    } else {
+        format!("https://slug.social/{}", tail)
+    }
+}
+
+pub fn item_path_segments(input: &str) -> Vec<String> {
+    let canonical = canonicalize_item(input);
+    if canonical.is_empty() {
+        return vec![];
+    }
+
+    if let Some(rest) = canonical.strip_prefix("https://") {
+        let (host, tail) = rest.split_once('/').map_or((rest, ""), |(h, t)| (h, t));
+        let mut out = vec![format!("https://{}", host)];
+        out.extend(tail.split('/').filter(|s| !s.is_empty()).map(|s| s.to_string()));
+        return out;
+    }
+    if let Some(rest) = canonical.strip_prefix("http://") {
+        let (host, tail) = rest.split_once('/').map_or((rest, ""), |(h, t)| (h, t));
+        let mut out = vec![format!("http://{}", host)];
+        out.extend(tail.split('/').filter(|s| !s.is_empty()).map(|s| s.to_string()));
+        return out;
+    }
+
+    canonical
+        .split('/')
+        .filter(|s| !s.is_empty())
+        .map(|s| s.to_string())
+        .collect()
+}
+
+pub fn item_parent_path(input: &str) -> Option<String> {
+    let segs = item_path_segments(input);
+    if segs.len() <= 1 {
+        return None;
+    }
+    Some(segs[..segs.len() - 1].join("/"))
+}
+
+// ---------------------------------------------------------------------------
+// Storage + input path newtypes
+// ---------------------------------------------------------------------------
+
+/// Canonical item identifier as produced by [`canonicalize_item`].
+///
+/// Shared across all scopes; room is not embedded. Usually
+/// `https://slug.social/~/…` or an external `http(s)://…` URL item.
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+pub struct CanonicalItemUrl(pub String);
+
+impl CanonicalItemUrl {
+    pub fn parse(input: &str) -> Option<Self> {
+        let c = canonicalize_item(input);
+        if c.is_empty() {
+            None
+        } else {
+            Some(Self(c))
+        }
+    }
+
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+
+    pub fn tilde_tail(&self) -> Option<&str> {
+        self.0.strip_prefix("https://slug.social/~/")
+    }
+
+    pub fn last_segment(&self) -> &str {
+        self.0
+            .rsplit('/')
+            .find(|s| !s.is_empty())
+            .unwrap_or(self.0.as_str())
+    }
+
+    pub fn ontology_root() -> Self {
+        Self("https://slug.social/~".to_string())
+    }
+
+    pub fn parent(&self) -> Option<Self> {
+        if self.tilde_tail().map(|t| t.is_empty()).unwrap_or(true) {
+            return None;
+        }
+        let last_slash = self.0.rfind('/')?;
+        let parent_str = &self.0[..last_slash];
+        if parent_str.is_empty() {
+            None
+        } else {
+            Some(Self(parent_str.to_string()))
+        }
+    }
+
+    pub fn tilde_segments(&self) -> Vec<&str> {
+        match self.tilde_tail() {
+            Some(tail) if !tail.is_empty() => {
+                std::iter::once("~")
+                    .chain(tail.split('/').filter(|s| !s.is_empty()))
+                    .collect()
+            }
+            Some(_) => vec!["~"],
+            None => vec![],
+        }
+    }
+
+    /// `~/…` list label for ontology items (paths index, CLI).
+    pub fn tilde_list_label(&self) -> TildeOntologyPath {
+        TildeOntologyPath::from_stored(self)
+    }
+
+    /// Absolute href for JSON/RPC and browsers for this stored id in `room`.
+    pub fn json_href(&self, room_wire: &str) -> GardenItemUrl {
+        GardenItemUrl::from_stored(self, room_wire)
+    }
+}
+
+impl fmt::Display for CanonicalItemUrl {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+impl Borrow<str> for CanonicalItemUrl {
+    fn borrow(&self) -> &str {
+        &self.0
+    }
+}
+
+impl PartialEq<str> for CanonicalItemUrl {
+    fn eq(&self, other: &str) -> bool {
+        self.0 == other
+    }
+}
+
+impl PartialEq<&str> for CanonicalItemUrl {
+    fn eq(&self, other: &&str) -> bool {
+        self.0 == *other
+    }
+}
+
+impl PartialEq<String> for CanonicalItemUrl {
+    fn eq(&self, other: &String) -> bool {
+        &self.0 == other
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+pub struct TildePath(pub String);
+
+impl TildePath {
+    pub fn new(input: &str) -> Option<Self> {
+        let s = input.trim();
+        if s.starts_with("~/") && s.len() > 2 {
+            Some(Self(s.to_string()))
+        } else if s == "~/" {
+            Some(Self("~/".to_string()))
+        } else {
+            None
+        }
+    }
+
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+
+    pub fn canonicalize(&self) -> Option<CanonicalItemUrl> {
+        CanonicalItemUrl::parse(&self.0)
+    }
+}
+
+impl fmt::Display for TildePath {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+pub struct RelativePath(pub String);
+
+impl RelativePath {
+    pub fn new(input: &str) -> Option<Self> {
+        let s = input.trim().trim_matches('/');
+        if s.is_empty() {
+            Some(Self(String::new()))
+        } else {
+            Some(Self(s.to_string()))
+        }
+    }
+
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+
+    pub fn join_under_ontology_root(&self, root: &CanonicalItemUrl) -> Option<CanonicalItemUrl> {
+        let base = root.tilde_tail()?;
+        let joined = if base.is_empty() {
+            if self.0.is_empty() {
+                "~/".to_string()
+            } else {
+                format!("~/{}", self.0)
+            }
+        } else if self.0.is_empty() {
+            format!("~/{}", base)
+        } else {
+            format!("~/{}/{}", base.trim_end_matches('/'), self.0)
+        };
+        CanonicalItemUrl::parse(&joined)
+    }
+}
+
+impl fmt::Display for RelativePath {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Wire / JSON: correct-by-construction hrefs
+// ---------------------------------------------------------------------------
+
+fn api_path_or_url(item: &str) -> String {
+    if item.starts_with("http://") || item.starts_with("https://") {
+        item.to_string()
+    } else {
+        format!("/{}", item)
+    }
+}
+
+/// Ontology item as serialized in JSON (absolute URL or `/`-prefixed path).
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+#[serde(transparent)]
+pub struct GardenItemUrl(pub String);
+
+impl GardenItemUrl {
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+
+    pub fn into_inner(self) -> String {
+        self.0
+    }
+
+    /// Stored canonical id + RPC `room` field (`"public"` or `"short/slug"`).
+    pub fn from_stored(stored: &CanonicalItemUrl, room_wire: &str) -> Self {
+        Self(garden_href_string(stored.as_str(), room_wire))
+    }
+
+    /// Like [`Self::from_stored`] but accepts a string that may already be canonical.
+    pub fn from_storage_str(stored: &str, room_wire: &str) -> Self {
+        Self(garden_href_string(stored, room_wire))
+    }
+}
+
+impl fmt::Display for GardenItemUrl {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+fn garden_href_string(item: &str, room_wire: &str) -> String {
+    let room = room_wire.trim();
+    if room.is_empty() || room == "public" {
+        return api_path_or_url(item);
+    }
+    let Some((short, slug)) = room.split_once('/') else {
+        return api_path_or_url(item);
+    };
+    if short.is_empty() || slug.is_empty() {
+        return api_path_or_url(item);
+    }
+    let Some(c) = CanonicalItemUrl::parse(item) else {
+        return api_path_or_url(item);
+    };
+    let root = CanonicalItemUrl::ontology_root();
+    let item_norm = c.as_str().trim_end_matches('/');
+    let root_norm = root.as_str().trim_end_matches('/');
+    if let Some(tail) = c.tilde_tail() {
+        return if tail.is_empty() {
+            format!("https://slug.social/r/{short}/{slug}/~")
+        } else {
+            format!("https://slug.social/r/{short}/{slug}/~/{}", tail)
+        };
+    }
+    if item_norm == root_norm {
+        return format!("https://slug.social/r/{short}/{slug}/~");
+    }
+    api_path_or_url(item)
+}
+
+/// Forum thread URL for JSON (`/t/…` or `/r/…/t/…` on slug.social).
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+#[serde(transparent)]
+pub struct ForumThreadUrl(pub String);
+
+impl ForumThreadUrl {
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+
+    pub fn into_inner(self) -> String {
+        self.0
+    }
+
+    pub fn from_room_tag(room_wire: &str, thread_tag: &str) -> Self {
+        let room = room_wire.trim();
+        let tag = thread_tag.trim().trim_start_matches('#');
+        Self(if room.is_empty() || room == "public" {
+            format!("https://slug.social/t/{tag}")
+        } else if let Some((short, slug)) = room.split_once('/') {
+            if short.is_empty() || slug.is_empty() {
+                format!("https://slug.social/t/{tag}")
+            } else {
+                format!("https://slug.social/r/{short}/{slug}/t/{tag}")
+            }
+        } else {
+            format!("https://slug.social/t/{tag}")
+        })
+    }
+}
+
+impl fmt::Display for ForumThreadUrl {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+/// `~/a/b` style path for list UIs (paths index `path` field).
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(transparent)]
+pub struct TildeOntologyPath(pub String);
+
+impl TildeOntologyPath {
+    pub fn from_stored(c: &CanonicalItemUrl) -> Self {
+        let s = match c.tilde_tail() {
+            Some(tail) if !tail.is_empty() => format!("~/{}", tail),
+            Some(_) => "~/".to_string(),
+            None => c.to_string(),
+        };
+        Self(s)
+    }
+
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+}
+
+impl fmt::Display for TildeOntologyPath {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn canonical_parent_deep() {
+        let c = CanonicalItemUrl::parse("~/a/b/c").unwrap();
+        assert_eq!(c.parent().unwrap().as_str(), "https://slug.social/~/a/b");
+    }
+
+    #[test]
+    fn canonical_parent_one_level() {
+        let c = CanonicalItemUrl::parse("~/a").unwrap();
+        assert_eq!(c.parent().unwrap().as_str(), "https://slug.social/~");
+    }
+
+    #[test]
+    fn canonical_parent_root_is_none() {
+        let root = CanonicalItemUrl::parse("~/").unwrap();
+        assert!(root.parent().is_none());
+    }
+
+    #[test]
+    fn tilde_segments_deep() {
+        let c = CanonicalItemUrl::parse("~/a/b").unwrap();
+        assert_eq!(c.tilde_segments(), vec!["~", "a", "b"]);
+    }
+
+    #[test]
+    fn tilde_segments_root() {
+        let c = CanonicalItemUrl::parse("~/").unwrap();
+        assert_eq!(c.tilde_segments(), vec!["~"]);
+    }
+
+    #[test]
+    fn tilde_segments_non_ontology_is_empty() {
+        let c = CanonicalItemUrl::parse("https://example.com/foo").unwrap();
+        assert_eq!(c.tilde_segments(), Vec::<&str>::new());
+    }
+
+    #[test]
+    fn garden_public_passthrough_https() {
+        let u = "https://slug.social/~/a/b";
+        assert_eq!(GardenItemUrl::from_storage_str(u, "public").as_str(), u);
+    }
+
+    #[test]
+    fn garden_private_room_prefixes_ontology() {
+        assert_eq!(
+            GardenItemUrl::from_storage_str("https://slug.social/~/topic/x", "9ab12cd/my-room").as_str(),
+            "https://slug.social/r/9ab12cd/my-room/~/topic/x"
+        );
+    }
+
+    #[test]
+    fn garden_private_room_ontology_root() {
+        assert_eq!(
+            GardenItemUrl::from_storage_str("https://slug.social/~", "9ab12cd/my-room").as_str(),
+            "https://slug.social/r/9ab12cd/my-room/~"
+        );
+        assert_eq!(
+            GardenItemUrl::from_storage_str("https://slug.social/~/", "9ab12cd/my-room").as_str(),
+            "https://slug.social/r/9ab12cd/my-room/~"
+        );
+    }
+
+    #[test]
+    fn garden_external_url_untouched_in_private_room() {
+        let u = "https://example.com/z";
+        assert_eq!(GardenItemUrl::from_storage_str(u, "9ab12cd/my-room").as_str(), u);
+    }
+
+    #[test]
+    fn forum_web_public_vs_room() {
+        assert_eq!(
+            ForumThreadUrl::from_room_tag("public", "debate").as_str(),
+            "https://slug.social/t/debate"
+        );
+        assert_eq!(
+            ForumThreadUrl::from_room_tag("9ab12cd/my-room", "#debate").as_str(),
+            "https://slug.social/r/9ab12cd/my-room/t/debate"
+        );
+    }
+}


Side B — contributor: tommy-mor
Side B — commit message:
[88577c56] reconfigure

Side B — unified diff (full patch):
diff --git a/server/src/api/ui_html.rs b/server/src/api/ui_html.rs
index c4ab9d65c7b3cd42a5b4d093ba429993c101e9a8..82b2aa51d21ada1d0d849d3ddfc3a81e4241d861 100644
--- a/server/src/api/ui_html.rs
+++ b/server/src/api/ui_html.rs
@@ -9,7 +9,9 @@ use crate::{
     html::{js_string_literal, ranking_panel, JsBuilder},
     parser::parse_reddit_url,
     parser_render::navigate_panel,
-    state::AppState,
+    path_types::ItemId,
+    reddit::ensure_partial_tree,
+    state::{parse_item_param, AppState},
     ui_action::{parse_html_ui_from_form, HtmlUiAction},
 };
 
@@ -25,6 +27,10 @@ fn ui_js_warn(msg: &str) -> Response {
         .unwrap()
 }
 
+fn parent_from_scope(scope: &str) -> ItemId {
+    parse_item_param(scope)
+}
+
 pub async fn post_ui_html(
     State(state): State<AppState>,
     Form(form): Form<HashMap<String, String>>,
@@ -42,24 +48,36 @@ pub async fn post_ui_html(
             ratio_right,
             scope,
         } => {
+            let parent = parent_from_scope(&scope);
             if let Err(e) = state
-                .record_vote(&scope, &a, &b, ratio_left, ratio_right)
+                .record_vote(&parent, &a, &b, ratio_left, ratio_right)
                 .await
             {
                 return ui_js_warn(&e).into_response();
             }
-            let scope = crate::state::normalize_scope(&scope);
-            let groups = state.groups.read().await;
+            let tree = state.tree.read().await;
             let empty = crate::reducer::GroupState::new();
-            let group = groups.get(&scope).unwrap_or(&empty);
-            let panel = ranking_panel(&scope, group);
+            let group = tree
+                .get(&parent)
+                .map(|n| &n.local_ranking)
+                .unwrap_or(&empty);
+            let panel = ranking_panel(&parent, group);
             JsBuilder::new()
                 .morph_selector("#ranking-panel", panel)
                 .into_response()
         }
         HtmlUiAction::ParseQuery { query } => match parse_reddit_url(&query) {
-            Ok(subreddit) => {
-                let dest = format!("/?sub={subreddit}");
+            Ok(item) => {
+                {
+                    let mut tree = state.tree.write().await;
+                    ensure_partial_tree(&mut tree, &item);
+                }
+                let _ = state.ensure_node(&item).await;
+                let dest = if item.is_root() {
+                    "/".to_string()
+                } else {
+                    format!("/?item={}", item.as_str())
+                };
                 JsBuilder::new()
                     .raw(&format!(
                         "window.location.href={};",
diff --git a/server/src/events.rs b/server/src/events.rs
index a862370fc840ffe02184a11c578e18239cc9474d..ed5be6b13b9d46e838831d6ce0f96f569b401730 100644
--- a/server/src/events.rs
+++ b/server/src/events.rs
@@ -5,8 +5,8 @@ use serde::{Deserialize, Serialize};
 pub enum Event {
     /// Page view recorded (path → counter in views.json).
     ViewRecorded { path: String, ts: i64 },
-    /// Pairwise comparison vote (replayed into the scope's [`crate::reducer::GroupState`] on boot).
-    /// `scope` is the ranking subject (e.g. a subreddit); empty string is the default/global scope.
+    /// Pairwise comparison vote (replayed into the parent node's [`crate::reducer::GroupState`] on boot).
+    /// `scope` is the parent [`crate::path_types::ItemId`] string; empty string is the tree root.
     VoteRecorded {
         ts: i64,
         a: String,
@@ -16,4 +16,6 @@ pub enum Event {
         #[serde(default)]
         scope: String,
     },
+    /// Register a node path in the fractal tree (no external fetch).
+    NodeEnsured { id: String },
 }
diff --git a/server/src/html/mod.rs b/server/src/html/mod.rs
index 9650d333d29c4ac94ceb407aee3ee00399c7f40b..c973cb718ac74b95570dabea76e24459417790b9 100644
--- a/server/src/html/mod.rs
+++ b/server/src/html/mod.rs
@@ -12,9 +12,10 @@ use serde::Deserialize;
 use crate::{
     form_template::template_json_compact,
     parser_render::navigate_panel,
+    path_types::ItemId,
     ranking::{top_bottom, RankedItem},
-    reducer::GroupState,
-    state::{normalize_scope, AppState},
+    reducer::{GroupState, NodeState},
+    state::{parse_item_param, AppState},
     ui_action::UI_RPC_FIELD,
 };
 
@@ -216,6 +217,48 @@ fn layout(title: &str, body: Markup, views: u64, theme: &str, theme_next: &str)
     }
 }
 
+fn item_href(id: &ItemId) -> String {
+    if id.is_root() {
+        "/".to_string()
+    } else {
+        format!("/?item={}", id.as_str())
+    }
+}
+
+fn segment_label(seg: &str) -> &str {
+    seg
+}
+
+/// Generic breadcrumb trail from an [`ItemId`] path.
+pub fn breadcrumb_path(item: &ItemId) -> Markup {
+    html! {
+        nav class="breadcrumbs" aria-label="Breadcrumb" {
+            a href="/" { "Internet" }
+            @for path in item.breadcrumb_paths() {
+                @let seg = path.segments().last().map_or("", |v| *v);
+                span class="separator" { " / " }
+                a href=(item_href(&path)) { (segment_label(seg)) }
+            }
+        }
+    }
+}
+
+fn entity_panel(node: &NodeState) -> Markup {
+    html! {
+        @if let Some(data) = &node.data {
+            section id="entity-panel" class="demo-panel entity-card" {
+                h2 { (data.title) }
+                @if let Some(author) = &data.author {
+                    p class="muted small" { "by " (author) }
+                }
+                @if let Some(body) = &data.body_html {
+                    div class="entity-body" { (maud::PreEscaped(body)) }
+                }
+            }
+        }
+    }
+}
+
 fn rank_list(label: &str, items: &[RankedItem], start_rank: usize) -> Markup {
     html! {
         @if !items.is_empty() {
@@ -224,7 +267,9 @@ fn rank_list(label: &str, items: &[RankedItem], start_rank: usize) -> Markup {
                 @for (i, r) in items.iter().enumerate() {
                     li {
                         span class="rank-num" { (start_rank + i) ". " }
-                        strong { (r.item.as_str()) }
+                        a href=(item_href(&r.item)) {
+                            strong { (display_label(&r.item)) }
+                        }
                         span class="muted" {
                             " — "
                             ({ format!("{:.1}%", r.score * 100.0) })
@@ -236,23 +281,30 @@ fn rank_list(label: &str, items: &[RankedItem], start_rank: usize) -> Markup {
     }
 }
 
-pub fn ranking_panel(scope: &str, group: &GroupState) -> Markup {
+fn display_label(id: &ItemId) -> String {
+    id.segments()
+        .last()
+        .map_or("Internet", |v| *v)
+        .to_string()
+}
+
+pub fn ranking_panel(item: &ItemId, group: &GroupState) -> Markup {
     let total = group.idx_to_item.len();
     let (top, bottom) = top_bottom(group, 8);
     html! {
         section id="ranking-panel" class="demo-panel" {
             h2 {
                 "Ranking"
-                @if !scope.is_empty() {
-                    " — " span class="scope-name" { "r/" (scope) }
+                @if !item.is_root() {
+                    " — " span class="scope-name" { (item.as_str()) }
                 }
             }
             @if total == 0 {
                 p class="muted" {
-                    @if scope.is_empty() {
+                    @if item.is_root() {
                         "No votes yet — compare two items below."
                     } @else {
-                        "No votes yet for r/" (scope) " — compare two items below to start the ranking."
+                        "No votes yet for " (item.as_str()) " — compare two items below to start the ranking."
                     }
                 }
             } @else {
@@ -266,7 +318,8 @@ pub fn ranking_panel(scope: &str, group: &GroupState) -> Markup {
     }
 }
 
-pub fn vote_panel(scope: &str) -> Markup {
+pub fn vote_panel(parent: &ItemId) -> Markup {
+    let parent_str = parent.as_str();
     let rpc = template_json_compact(&serde_json::json!({
         "action": "record_vote",
         "a": {"$form": "item_a"},
@@ -280,16 +333,17 @@ pub fn vote_panel(scope: &str) -> Markup {
         section id="vote-panel" class="demo-panel" {
             h2 { "Compare" }
             p class="muted small" {
-                @if scope.is_empty() {
+                @if parent.is_root() {
                     "Left item wins at 2:1. Votes append to the JSONL log and update rank centrality."
                 } @else {
-                    "Ranking " span class="scope-name" { "r/" (scope) }
+                    "Ranking children of "
+                    span class="scope-name" { (parent_str) }
                     ". Left item wins at 2:1; each vote updates this ranking."
                 }
             }
             form method="post" action="/ui" id="vote-form" {
                 input type="hidden" name=(UI_RPC_FIELD) value=(rpc);
-                input type="hidden" name="scope" value=(scope);
+                input type="hidden" name="scope" value=(parent_str);
                 div class="vote-fields" {
                     label {
                         "Left (wins) "
@@ -329,17 +383,30 @@ pub async fn home(
     let views = state.views.get_views(&path);
     let theme = theme_from_jar(&jar);
     let theme_next = theme_next_from_uri(&uri);
-    let scope = normalize_scope(&query_param(&uri, "sub").unwrap_or_default());
 
-    let groups = state.groups.read().await;
-    let empty = GroupState::new();
-    let group = groups.get(&scope).unwrap_or(&empty);
+    let item_raw = query_param(&uri, "item")
+        .or_else(|| query_param(&uri, "sub").map(|sub| {
+            if sub.is_empty() {
+                String::new()
+            } else {
+                format!("reddit.com/r/{sub}")
+            }
+        }))
+        .unwrap_or_default();
+    let item = parse_item_param(&item_raw);
+
+    let tree = state.tree.read().await;
+    let empty_node = NodeState::default();
+    let node = tree.get(&item).unwrap_or(&empty_node);
+    let group = &node.local_ranking;
 
     let body = html! {
         h1 { "sorter2" }
+        (breadcrumb_path(&item))
         (navigate_panel("", None))
-        (vote_panel(&scope))
-        (ranking_panel(&scope, group))
+        (entity_panel(node))
+        (vote_panel(&item))
+        (ranking_panel(&item, group))
     };
     layout("sorter2", body, views, theme, &theme_next)
 }
diff --git a/server/src/journal.rs b/server/src/journal.rs
new file mode 100644
index 0000000000000000000000000000000000000000..b02ca025683621470ffdf8cd85cf9b85c56d024d
--- /dev/null
+++ b/server/src/journal.rs
@@ -0,0 +1,89 @@
+use std::sync::Arc;
+
+use tokio::sync::{mpsc, oneshot, RwLock};
+
+use crate::{
+    event_log::EventLog,
+    events::Event,
+    path_types::ItemId,
+    reducer::{GlobalTree, VoteData},
+};
+
+pub struct JournalCommand {
+    pub parent: ItemId,
+    pub vote: VoteData,
+    pub event: Event,
+    pub reply: oneshot::Sender<Result<(), String>>,
+}
+
+#[derive(Clone)]
+pub struct JournalClient {
+    tx: mpsc::Sender<JournalCommand>,
+}
+
+impl JournalClient {
+    pub fn spawn(tree: Arc<RwLock<GlobalTree>>, event_log: Arc<EventLog>) -> Self {
+        let (tx, rx) = mpsc::channel(64);
+        tokio::spawn(journal_worker(rx, tree, event_log));
+        Self { tx }
+    }
+
+    pub async fn record_vote(
+        &self,
+        parent: ItemId,
+        vote: VoteData,
+        event: Event,
+    ) -> Result<(), String> {
+        let (reply, rx) = oneshot::channel();
+        self.tx
+            .send(JournalCommand {
+                parent,
+                vote,
+                event,
+                reply,
+            })
+            .await
+            .map_err(|_| "journal worker stopped".to_string())?;
+        rx.await
+            .map_err(|_| "journal worker stopped".to_string())?
+    }
+}
+
+async fn journal_worker(
+    mut rx: mpsc::Receiver<JournalCommand>,
+    tree: Arc<RwLock<GlobalTree>>,
+    event_log: Arc<EventLog>,
+) {
+    while let Some(first) = rx.recv().await {
+        let mut batch = vec![first];
+        while let Ok(more) = rx.try_recv() {
+            batch.push(more);
+        }
+
+        let mut disk_err: Option<String> = None;
+        for cmd in &batch {
+            if let Err(e) = event_log.append(&cmd.event).await {
+                disk_err = Some(e.to_string());
+                break;
+            }
+        }
+
+        if let Some(err) = disk_err {
+            for cmd in batch {
+                let _ = cmd.reply.send(Err(err.clone()));
+            }
+            continue;
+        }
+
+        {
+            let mut w = tree.write().await;
+            for cmd in &batch {
+                w.apply_vote(&cmd.parent, cmd.vote.clone());
+            }
+        }
+
+        for cmd in batch {
+            let _ = cmd.reply.send(Ok(()));
+        }
+    }
+}
diff --git a/server/src/lib.rs b/server/src/lib.rs
index de8bca48cbf689cad22337883e7791966e7c4919..14e7cfbc38feb5d07aff859b64bce6e2ec45cf91 100644
--- a/server/src/lib.rs
+++ b/server/src/lib.rs
@@ -7,8 +7,9 @@ pub mod parser;
 pub mod parser_render;
 pub mod path_types;
 pub mod ranking;
+pub mod reddit;
 pub mod reducer;
-pub mod settlement;
+pub mod journal;
 pub mod state;
 pub mod ui_action;
 pub mod views;
diff --git a/server/src/parser.rs b/server/src/parser.rs
index 50571a59f0d3ece1e2538f88e00ef46ec40ea545..51aa0e0f982546aab68bd5e1ca0cb726e88b3f50 100644
--- a/server/src/parser.rs
+++ b/server/src/parser.rs
@@ -1,47 +1,18 @@
-//! Extract a subreddit name from a pasted Reddit URL or path.
+//! Extract a canonical [`crate::path_types::ItemId`] from a pasted Reddit URL or path.
 
-pub fn parse_reddit_url(query: &str) -> Result<String, String> {
+use crate::path_types::ItemId;
+
+pub fn parse_reddit_url(query: &str) -> Result<ItemId, String> {
     let q = query.trim();
     if q.is_empty() {
         return Err("Paste a Reddit URL or r/subreddit path".into());
     }
 
-    if let Some(sub) = subreddit_after_prefix(q, "r/") {
-        return Ok(sub);
-    }
-
-    if let Some(sub) = subreddit_from_path_segment(q, "/r/") {
-        return Ok(sub);
+    if let Some(id) = ItemId::from_url(q) {
+        return Ok(id);
     }
 
-    Err("Could not find a subreddit in that URL".into())
-}
-
-fn subreddit_after_prefix(text: &str, prefix: &str) -> Option<String> {
-    let rest = text.strip_prefix(prefix)?;
-    let sub = rest.split(['/', '?', '#']).next()?.trim();
-    valid_subreddit(sub)
-}
-
-fn subreddit_from_path_segment(text: &str, needle: &str) -> Option<String> {
-    let idx = text.find(needle)?;
-    let rest = &text[idx + needle.len()..];
-    let sub = rest.split(['/', '?', '#']).next()?.trim();
-    valid_subreddit(sub)
-}
-
-fn valid_subreddit(name: &str) -> Option<String> {
-    if name.is_empty() {
-        return None;
-    }
-    if name
-        .chars()
-        .all(|c| c.is_ascii_alphanumeric() || c == '_')
-    {
-        Some(name.to_ascii_lowercase())
-    } else {
-        None
-    }
+    Err("Could not parse that Reddit URL".into())
 }
 
 #[cfg(test)]
@@ -50,34 +21,37 @@ mod tests {
 
     #[test]
     fn parses_short_path() {
-        assert_eq!(parse_reddit_url("r/rust").unwrap(), "rust");
-    }
-
-    #[test]
-    fn parses_path_with_trailing_slash() {
-        assert_eq!(parse_reddit_url("r/rust/").unwrap(), "rust");
+        assert_eq!(
+            parse_reddit_url("r/rust").unwrap().as_str(),
+            "reddit.com/r/rust"
+        );
     }
 
     #[test]
     fn parses_full_url() {
         assert_eq!(
-            parse_reddit_url("https://www.reddit.com/r/programming/hot").unwrap(),
-            "programming"
+            parse_reddit_url("https://www.reddit.com/r/programming/hot")
+                .unwrap()
+                .as_str(),
+            "reddit.com/r/programming"
         );
     }
 
     #[test]
-    fn parses_url_without_scheme() {
+    fn parses_post_url() {
+        let id = parse_reddit_url(
+            "https://old.reddit.com/r/AmItheAsshole/comments/1trnvdl/aita_for_cancelling/",
+        )
+        .unwrap();
         assert_eq!(
-            parse_reddit_url("reddit.com/r/AskReddit").unwrap(),
-            "askreddit"
+            id.as_str(),
+            "reddit.com/r/amitheasshole/comments/1trnvdl"
         );
     }
 
     #[test]
     fn rejects_empty() {
         assert!(parse_reddit_url("").is_err());
-        assert!(parse_reddit_url("   ").is_err());
     }
 
     #[test]
diff --git a/server/src/parser_render.rs b/server/src/parser_render.rs
index f2341afe21476b689a536137798d97277211a962..acf2e7403f4238291677ef0c79d5766302ea78cf 100644
--- a/server/src/parser_render.rs
+++ b/server/src/parser_render.rs
@@ -21,7 +21,7 @@ pub fn navigate_panel(query: &str, error: Option<&str>) -> Markup {
             p class="muted small" {
                 "Paste a Reddit URL or "
                 code { "r/subreddit" }
-                " path, then click Go to rank that subreddit."
+                " path. Breadcrumb links drill down the tree; rankings apply to each node's children."
             }
             form method="post" action="/ui" id="parser-form" {
                 textarea
diff --git a/server/src/path_types.rs b/server/src/path_types.rs
index 1cdc96a25b1954f11aaf955203e2b9907b578366..b5c41444f7bcd4d8d289ed3af464bc3f14d0df99 100644
--- a/server/src/path_types.rs
+++ b/server/src/path_types.rs
@@ -1,11 +1,13 @@
 use serde::{Deserialize, Serialize};
 use std::fmt;
 
-/// Stable item key for votes and rankings (opaque string for now).
-#[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
+/// Canonical hierarchical identity for any URL/path in the fractal tree.
+#[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize, Default)]
 pub struct ItemId(String);
 
 impl ItemId {
+    /// Parse an already-canonical path (no URL normalization). Empty string is invalid here;
+    /// use [`Self::root`] for the tree root.
     pub fn parse(s: &str) -> Option<Self> {
         let t = s.trim();
         if t.is_empty() {
@@ -14,13 +16,170 @@ impl ItemId {
         Some(Self(t.to_string()))
     }
 
+    /// Build an opaque item key (legacy demo votes, non-URL items).
     pub fn opaque(s: impl Into<String>) -> Self {
         Self(s.into())
     }
 
+    /// Root of the internet tree (empty path).
+    pub fn root() -> Self {
+        Self(String::new())
+    }
+
+    pub fn is_root(&self) -> bool {
+        self.0.is_empty()
+    }
+
     pub fn as_str(&self) -> &str {
         &self.0
     }
+
+    /// Creates a canonical ID from a raw URL or path. Normalizes domains and
+    /// trims tracking query params.
+    pub fn from_url(raw_url: &str) -> Option<Self> {
+        Self::canonicalize(raw_url).map(Self)
+    }
+
+    /// Map legacy scope keys (`""`, `"rust"`) to fractal parent nodes.
+    pub fn from_legacy_scope(raw: &str) -> Self {
+        let s = raw.trim();
+        if s.is_empty() {
+            return Self::root();
+        }
+        Self(format!("reddit.com/r/{s}"))
+    }
+
+    /// Extract the parent, e.g. `reddit.com/r/aww/comments/1trnvdl` →
+    /// `reddit.com/r/aww`.
+    pub fn parent(&self) -> Option<Self> {
+        if self.0.is_empty() {
+            return None;
+        }
+
+        let parts: Vec<&str> = self.0.trim_end_matches('/').split('/').collect();
+        if parts.len() <= 1 {
+            return None;
+        }
+
+        if self.0.contains("/comments/") {
+            return Some(Self(parts[..parts.len().saturating_sub(2)].join("/")));
+        }
+
+        Some(Self(parts[..parts.len() - 1].join("/")))
+    }
+
+    pub fn segments(&self) -> Vec<&str> {
+        self.0.split('/').filter(|s| !s.is_empty()).collect()
+    }
+
+    /// Cumulative paths for breadcrumb rendering, e.g.
+    /// `reddit.com/r/movies` → `["reddit.com", "reddit.com/r", "reddit.com/r/movies"]`.
+    pub fn breadcrumb_paths(&self) -> Vec<ItemId> {
+        let segs = self.segments();
+        let mut paths = Vec::with_capacity(segs.len());
+        let mut current = String::new();
+        for seg in segs {
+            if current.is_empty() {
+                current = seg.to_string();
+            } else {
+                current.push('/');
+                current.push_str(seg);
+            }
+            paths.push(ItemId(current.clone()));
+        }
+        paths
+    }
+
+    fn canonicalize(raw: &str) -> Option<String> {
+        let s = raw.trim();
+        if s.is_empty() {
+            return None;
+        }
+
+        let owned = if let Some(rest) = s.strip_prefix("r/") {
+            format!("reddit.com/r/{rest}")
+        } else if let Some(rest) = s.strip_prefix("/r/") {
+            format!("reddit.com/r/{rest}")
+        } else {
+            s.to_string()
+        };
+
+        let (host_path, _query) = split_query(&owned);
+        let host_path = host_path.trim_end_matches('/');
+
+        let path = if host_path.contains("://") {
+            parse_url_host_path(host_path)?
+        } else if host_path.starts_with("reddit.com") || host_path.starts_with("www.reddit.com") {
+            normalize_reddit_host_path(host_path)
+        } else if host_path.contains('/') {
+            host_path.to_string()
+        } else {
+            return None;
+        };
+
+        Some(normalize_reddit_path(&path))
+    }
+}
+
+fn split_query(s: &str) -> (&str, Option<&str>) {
+    if let Some((path, q)) = s.split_once('?') {
+        (path, Some(q))
+    } else {
+        (s, None)
+    }
+}
+
+fn parse_url_host_path(url: &str) -> Option<String> {
+    let rest = url
+        .strip_prefix("https://")
+        .or_else(|| url.strip_prefix("http://"))
+        .unwrap_or(url);
+    let (host, path) = rest.split_once('/').unwrap_or((rest, ""));
+    let host = normalize_host(host);
+    if path.is_empty() {
+        Some(host)
+    } else {
+        Some(format!("{host}/{path}"))
+    }
+}
+
+fn normalize_host(host: &str) -> String {
+    let h = host
+        .strip_prefix("www.")
+        .unwrap_or(host)
+        .to_ascii_lowercase();
+    if h == "old.reddit.com" || h == "new.reddit.com" || h == "reddit.com" {
+        "reddit.com".to_string()
+    } else {
+        h
+    }
+}
+
+fn normalize_reddit_host_path(s: &str) -> String {
+    let (host, path) = s.split_once('/').unwrap_or((s, ""));
+    let host = normalize_host(host);
+    if path.is_empty() {
+        host
+    } else {
+        format!("{host}/{path}")
+    }
+}
+
+/// Lowercase subreddit segment, drop listing suffixes, drop title slug after post id.
+fn normalize_reddit_path(path: &str) -> String {
+    let mut parts: Vec<String> = path.split('/').map(str::to_string).collect();
+    if parts.len() >= 3 && parts[1] == "r" {
+        parts[2] = parts[2].to_ascii_lowercase();
+    }
+    if let Some(i) = parts.iter().position(|p| p == "comments") {
+        if parts.len() > i + 2 {
+            parts.truncate(i + 2);
+        }
+    } else if parts.len() > 3 && parts.get(1).map(|s| s.as_str()) == Some("r") {
+        // reddit.com/r/{sub}/hot → reddit.com/r/{sub}
+        parts.truncate(3);
+    }
+    parts.join("/")
 }
 
 impl fmt::Display for ItemId {
@@ -28,3 +187,69 @@ impl fmt::Display for ItemId {
         f.write_str(&self.0)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn from_url_normalizes_reddit_domains() {
+        let id = ItemId::from_url(
+            "https://old.reddit.com/r/AmItheAsshole/comments/1trnvdl/aita_for_cancelling/",
+        )
+        .unwrap();
+        assert_eq!(
+            id.as_str(),
+            "reddit.com/r/amitheasshole/comments/1trnvdl"
+        );
+    }
+
+    #[test]
+    fn from_url_strips_query() {
+        let id = ItemId::from_url("https://www.reddit.com/r/rust/?sort=top").unwrap();
+        assert_eq!(id.as_str(), "reddit.com/r/rust");
+    }
+
+    #[test]
+    fn from_url_short_path() {
+        assert_eq!(
+            ItemId::from_url("r/rust").unwrap().as_str(),
+            "reddit.com/r/rust"
+        );
+    }
+
+    #[test]
+    fn parent_of_post_is_subreddit() {
+        let id = ItemId::parse("reddit.com/r/aww/comments/1trnvdl").unwrap();
+        assert_eq!(
+            id.parent().unwrap().as_str(),
+            "reddit.com/r/aww"
+        );
+    }
+
+    #[test]
+    fn parent_of_subreddit_is_r_segment() {
+        let id = ItemId::parse("reddit.com/r/movies").unwrap();
+        assert_eq!(id.parent().unwrap().as_str(), "reddit.com/r");
+    }
+
+    #[test]
+    fn breadcrumb_paths() {
+        let id = ItemId::parse("reddit.com/r/movies").unwrap();
+        let crumbs = id.breadcrumb_paths();
+        let paths: Vec<_> = crumbs.iter().map(|p| p.as_str()).collect();
+        assert_eq!(
+            paths,
+            vec!["reddit.com", "reddit.com/r", "reddit.com/r/movies"]
+        );
+    }
+
+    #[test]
+    fn legacy_scope_maps_to_reddit_sub() {
+        assert_eq!(
+            ItemId::from_legacy_scope("rust").as_str(),
+            "reddit.com/r/rust"
+        );
+        assert!(ItemId::from_legacy_scope("").is_root());
+    }
+}
diff --git a/server/src/reddit.rs b/server/src/reddit.rs
new file mode 100644
index 0000000000000000000000000000000000000000..d203dca09245daf869b3aa942898447700ae69fb
--- /dev/null
+++ b/server/src/reddit.rs
@@ -0,0 +1,21 @@
+//! Reddit API import (async, decoupled from UI request path).
+
+use crate::{
+    path_types::ItemId,
+    reducer::{EntityData, GlobalTree},
+};
+
+/// Bootstrap blank nodes along a URL path so breadcrumbs and voting work before fetch.
+pub fn ensure_partial_tree(tree: &mut GlobalTree, id: &ItemId) {
+    tree.ensure_path(id);
+}
+
+/// Placeholder for Reddit JSON import. Returns entity data when implemented.
+pub async fn fetch_reddit_entity(_id: &ItemId) -> Option<EntityData> {
+    None
+}
+
+/// Apply fetched entity data to a node (called from async worker).
+pub fn apply_entity(tree: &mut GlobalTree, id: &ItemId, data: EntityData) {
+    tree.set_entity_data(id, data);
+}
diff --git a/server/src/reducer.rs b/server/src/reducer.rs
index 8d28353e1f2a67e71b7d17a2041a0988150f3245..077f700bf00ddefe18ffd004bb5288bdc7c4adaf 100644
--- a/server/src/reducer.rs
+++ b/server/src/reducer.rs
@@ -115,6 +115,96 @@ impl GroupState {
     }
 }
 
+/// Structured data imported from Reddit or elsewhere.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct EntityData {
+    pub title: String,
+    pub author: Option<String>,
+    pub body_html: Option<String>,
+    pub thumb_url: Option<String>,
+}
+
+/// One node in the fractal tree: entity + ranked children.
+#[derive(Debug, Clone, Default)]
+pub struct NodeState {
+    pub id: ItemId,
+    pub data: Option<EntityData>,
+    pub children: HashSet<ItemId>,
+    pub local_ranking: GroupState,
+}
+
+impl NodeState {
+    fn new(id: ItemId) -> Self {
+        Self {
+            id,
+            ..Default::default()
+        }
+    }
+}
+
+/// Global fractal graph: every URL is both an item and a ranking scope for its children.
+#[derive(Default)]
+pub struct GlobalTree {
+    pub nodes: HashMap<ItemId, NodeState>,
+}
+
+impl GlobalTree {
+    pub fn new() -> Self {
+        let mut tree = Self::default();
+        tree.ensure_node(&ItemId::root());
+        tree
+    }
+
+    pub fn ensure_node(&mut self, id: &ItemId) -> &mut NodeState {
+        if !self.nodes.contains_key(id) {
+            self.nodes.insert(id.clone(), NodeState::new(id.clone()));
+        }
+        self.nodes.get_mut(id).expect("node just inserted")
+    }
+
+    /// Register a node and wire parent→child links along the canonical path.
+    pub fn ensure_path(&mut self, id: &ItemId) {
+        if id.is_root() {
+            self.ensure_node(id);
+            return;
+        }
+        self.ensure_node(&ItemId::root());
+        for path in id.breadcrumb_paths() {
+            self.ensure_node(&path);
+            if let Some(parent) = path.parent() {
+                self.ensure_node(&parent);
+                if let Some(p) = self.nodes.get_mut(&parent) {
+                    p.children.insert(path.clone());
+                }
+            } else if let Some(r) = self.nodes.get_mut(&ItemId::root()) {
+                r.children.insert(path.clone());
+            }
+        }
+    }
+
+    pub fn get(&self, id: &ItemId) -> Option<&NodeState> {
+        self.nodes.get(id)
+    }
+
+    pub fn apply_vote(&mut self, parent: &ItemId, vote: VoteData) {
+        self.ensure_path(parent);
+        self.ensure_path(&vote.a);
+        self.ensure_path(&vote.b);
+        if let Some(node) = self.nodes.get_mut(parent) {
+            node.children.insert(vote.a.clone());
+            node.children.insert(vote.b.clone());
+            node.local_ranking.apply_vote(vote);
+        }
+    }
+
+    pub fn set_entity_data(&mut self, id: &ItemId, data: EntityData) {
+        self.ensure_path(id);
+        if let Some(node) = self.nodes.get_mut(id) {
+            node.data = Some(data);
+        }
+    }
+}
+
 #[cfg(test)]
 mod from_recorded_tests {
     use super::*;
@@ -125,7 +215,20 @@ mod from_recorded_tests {
     }
 
     #[test]
-    fn rejects_empty() {
+    fn rejects_empty_pair() {
         assert!(VoteData::from_recorded(1, "", "b", 2, 1).is_none());
     }
+
+    #[test]
+    fn ensure_path_wires_children() {
+        let mut tree = GlobalTree::new();
+        let id = ItemId::parse("reddit.com/r/rust").unwrap();
+        tree.ensure_path(&id);
+        let root = tree.get(&ItemId::root()).unwrap();
+        assert!(root.children.contains(&ItemId::parse("reddit.com").unwrap()));
+        let reddit = tree.get(&ItemId::parse("reddit.com").unwrap()).unwrap();
+        assert!(reddit.children.contains(&ItemId::parse("reddit.com/r").unwrap()));
+        let sub = tree.get(&id).unwrap();
+        assert_eq!(sub.id, id);
+    }
 }
diff --git a/server/src/settlement.rs b/server/src/settlement.rs
deleted file mode 100644
index 7a44495512b7f788239b8aeefbbd0a83656eeac6..0000000000000000000000000000000000000000
--- a/server/src/settlement.rs
+++ /dev/null
@@ -1,94 +0,0 @@
-use std::collections::HashMap;
-use std::sync::Arc;
-
-use tokio::sync::{mpsc, oneshot, RwLock};
-
-use crate::{
-    event_log::EventLog,
-    events::Event,
-    reducer::{GroupState, VoteData},
-};
-
-/// Per-scope ranking state, keyed by scope (e.g. subreddit; "" is the default scope).
-pub type GroupMap = HashMap<String, GroupState>;
-
-pub struct SettlementCommand {
-    pub scope: String,
-    pub vote: VoteData,
-    pub event: Event,
-    pub reply: oneshot::Sender<Result<(), String>>,
-}
-
-#[derive(Clone)]
-pub struct SettlementClient {
-    tx: mpsc::Sender<SettlementCommand>,
-}
-
-impl SettlementClient {
-    pub fn spawn(groups: Arc<RwLock<GroupMap>>, event_log: Arc<EventLog>) -> Self {
-        let (tx, rx) = mpsc::channel(64);
-        tokio::spawn(settlement_worker(rx, groups, event_log));
-        Self { tx }
-    }
-
-    pub async fn record_vote(
-        &self,
-        scope: String,
-        vote: VoteData,
-        event: Event,
-    ) -> Result<(), String> {
-        let (reply, rx) = oneshot::channel();
-        self.tx
-            .send(SettlementCommand {
-                scope,
-                vote,
-                event,
-                reply,
-            })
-            .await
-            .map_err(|_| "settlement worker stopped".to_string())?;
-        rx.await
-            .map_err(|_| "settlement worker stopped".to_string())?
-    }
-}
-
-async fn settlement_worker(
-    mut rx: mpsc::Receiver<SettlementCommand>,
-    groups: Arc<RwLock<GroupMap>>,
-    event_log: Arc<EventLog>,
-) {
-    while let Some(first) = rx.recv().await {
-        let mut batch = vec![first];
-        while let Ok(more) = rx.try_recv() {
-            batch.push(more);
-        }
-
-        let mut disk_err: Option<String> = None;
-        for cmd in &batch {
-            if let Err(e) = event_log.append(&cmd.event).await {
-                disk_err = Some(e.to_string());
-                break;
-            }
-        }
-
-        if let Some(err) = disk_err {
-            for cmd in batch {
-                let _ = cmd.reply.send(Err(err.clone()));
-            }
-            continue;
-        }
-
-        {
-            let mut w = groups.write().await;
-            for cmd in &batch {
-                w.entry(cmd.scope.clone())
-                    .or_default()
-                    .apply_vote(cmd.vote.clone());
-            }
-        }
-
-        for cmd in batch {
-            let _ = cmd.reply.send(Ok(()));
-        }
-    }
-}
diff --git a/server/src/state.rs b/server/src/state.rs
index 2d9e5226057f8615897aac48bce947643a230fb4..cc1722f5a5bf4d415f2327ea585c488a15a75592 100644
--- a/server/src/state.rs
+++ b/server/src/state.rs
@@ -1,4 +1,3 @@
-use std::collections::HashMap;
 use std::sync::Arc;
 
 use tokio::sync::RwLock;
@@ -6,14 +5,22 @@ use tokio::sync::RwLock;
 use crate::{
     event_log::EventLog,
     events::Event,
-    reducer::VoteData,
-    settlement::{GroupMap, SettlementClient},
+    path_types::ItemId,
+    reducer::{GlobalTree, VoteData},
+    journal::JournalClient,
     views::ViewStore,
 };
 
-/// Normalize a raw ranking subject into a scope key: strip an optional `r/`
-/// prefix, keep only `[a-z0-9_]`, lowercase, and cap the length. Empty string
-/// is the default/global scope.
+/// Parse `?item=` query value into a canonical node id.
+pub fn parse_item_param(raw: &str) -> ItemId {
+    let s = raw.trim();
+    if s.is_empty() {
+        return ItemId::root();
+    }
+    ItemId::from_url(s).or_else(|| ItemId::parse(s)).unwrap_or_else(|| ItemId::opaque(s))
+}
+
+/// Legacy: normalize raw ranking subject into a scope key for old event replay.
 pub fn normalize_scope(raw: &str) -> String {
     let s = raw.trim();
     let s = s
@@ -27,6 +34,14 @@ pub fn normalize_scope(raw: &str) -> String {
         .collect()
 }
 
+fn parent_from_event_scope(scope: &str) -> ItemId {
+    if scope.contains('/') {
+        ItemId::parse(scope).unwrap_or_else(|| ItemId::from_legacy_scope(scope))
+    } else {
+        ItemId::from_legacy_scope(scope)
+    }
+}
+
 #[derive(Clone)]
 pub struct AppConfig {
     pub data_dir: String,
@@ -56,8 +71,8 @@ pub struct AppState {
     pub cfg: Arc<AppConfig>,
     pub event_log: Arc<EventLog>,
     pub views: ViewStore,
-    pub groups: Arc<RwLock<GroupMap>>,
-    settlement: SettlementClient,
+    pub tree: Arc<RwLock<GlobalTree>>,
+    journal: JournalClient,
 }
 
 impl AppState {
@@ -66,7 +81,7 @@ impl AppState {
         let views_path = format!("{}/views.json", cfg.data_dir);
         let views = ViewStore::new(&views_path);
 
-        let mut groups: GroupMap = HashMap::new();
+        let mut tree = GlobalTree::new();
         if let Ok((events, _)) = event_log.load_all().await {
             for ev in events {
                 match ev {
@@ -81,29 +96,45 @@ impl AppState {
                         if let Some(vote) =
                             VoteData::from_recorded(ts, &a, &b, ratio_left, ratio_right)
                         {
-                            groups.entry(scope).or_default().apply_vote(vote);
+                            let parent = parent_from_event_scope(&scope);
+                            tree.apply_vote(&parent, vote);
                         }
                     }
                     Event::ViewRecorded { .. } => {}
+                    Event::NodeEnsured { id } => {
+                        if let Some(parsed) = ItemId::parse(&id).or_else(|| ItemId::from_url(&id)) {
+                            tree.ensure_path(&parsed);
+                        }
+                    }
                 }
             }
         }
 
-        let groups = Arc::new(RwLock::new(groups));
-        let settlement = SettlementClient::spawn(groups.clone(), event_log.clone());
+        let tree = Arc::new(RwLock::new(tree));
+        let journal = JournalClient::spawn(tree.clone(), event_log.clone());
 
         Self {
             cfg: Arc::new(cfg),
             event_log,
             views,
-            groups,
-            settlement,
+            tree,
+            journal,
         }
     }
 
+    pub async fn ensure_node(&self, id: &ItemId) -> Result<(), String> {
+        let event = Event::NodeEnsured {
+            id: id.as_str().to_string(),
+        };
+        self.event_log.append(&event).await.map_err(|e| e.to_string())?;
+        let mut w = self.tree.write().await;
+        w.ensure_path(id);
+        Ok(())
+    }
+
     pub async fn record_vote(
         &self,
-        scope: &str,
+        parent: &ItemId,
         a: &str,
         b: &str,
         ratio_left: i32,
@@ -113,23 +144,24 @@ impl AppState {
         let vote = VoteData::from_recorded(ts, a, b, ratio_left, ratio_right)
             .ok_or_else(|| "invalid vote: need two distinct non-empty items".to_string())?;
 
-        let scope = normalize_scope(scope);
         let event = Event::VoteRecorded {
             ts,
             a: vote.a.as_str().to_string(),
             b: vote.b.as_str().to_string(),
             ratio_left: vote.ratio_left,
             ratio_right: vote.ratio_right,
-            scope: scope.clone(),
+            scope: parent.as_str().to_string(),
         };
 
-        self.settlement.record_vote(scope, vote, event).await
+        self.journal
+            .record_vote(parent.clone(), vote, event)
+            .await
     }
 }
 
 #[cfg(test)]
 mod tests {
-    use super::normalize_scope;
+    use super::{normalize_scope, parse_item_param};
 
     #[test]
     fn normalize_scope_strips_prefix_and_lowercases() {
@@ -138,4 +170,15 @@ mod tests {
         assert_eq!(normalize_scope("r/web_dev!!"), "web_dev");
         assert_eq!(normalize_scope(""), "");
     }
+
+    #[test]
+    fn parse_item_param_from_url() {
+        let id = parse_item_param("https://reddit.com/r/rust");
+        assert_eq!(id.as_str(), "reddit.com/r/rust");
+    }
+
+    #[test]
+    fn parse_item_param_empty_is_root() {
+        assert!(parse_item_param("").is_root());
+    }
 }
diff --git a/server/src/ui_action.rs b/server/src/ui_action.rs
index 0e030b3448b8e45acbe49d2de47ea26372445c54..d798874d1d94c0dfee59ec1ff703f9ee6ef432c0 100644
--- a/server/src/ui_action.rs
+++ b/server/src/ui_action.rs
@@ -18,7 +18,7 @@ pub enum HtmlUiAction {
         b: String,
         ratio_left: i32,
         ratio_right: i32,
-        /// Ranking subject (e.g. a subreddit). Empty string = default/global scope.
+        /// Parent node [`ItemId`] string; empty = tree root.
         #[serde(default)]
         scope: String,
     },
diff --git a/server/static/theme_default.css b/server/static/theme_default.css
index 6ad0ac712bbc840bedee60f613794de9385fbbd1..1bf8ac7a25207336c019f93cd4119bd0e06229f0 100644
--- a/server/static/theme_default.css
+++ b/server/static/theme_default.css
@@ -137,6 +137,38 @@ code {
   margin-top: 0.5rem;
 }
 
+.breadcrumbs {
+  font-size: 0.875rem;
+  margin-bottom: 1rem;
+  color: var(--muted);
+}
+
+.breadcrumbs a {
+  color: var(--accent);
+  text-decoration: none;
+}
+
+.breadcrumbs a:hover {
+  text-decoration: underline;
+}
+
+.breadcrumbs .separator {
+  color: var(--muted);
+}
+
+.rank-list a {
+  color: var(--accent);
+  text-decoration: none;
+}
+
+.rank-list a:hover {
+  text-decoration: underline;
+}
+
+.entity-card h2 {
+  margin-top: 0;
+}
+
 .scope-name {
   color: var(--accent);
   font-weight: 600;
diff --git a/server/tests/integration_ui.rs b/server/tests/integration_ui.rs
index afeeee24e32f2d7f1d852ca96ac799fac8bce665..f7ac9c26bf9f9277ad5f5708603224c095165fb8 100644
--- a/server/tests/integration_ui.rs
+++ b/server/tests/integration_ui.rs
@@ -2,7 +2,7 @@ use std::collections::HashMap;
 use std::net::SocketAddr;
 
 use axum::Router;
-use sorter2_server::{create_app, create_app_state, state::AppConfig, ui_action::UI_RPC_FIELD};
+use sorter2_server::{create_app, create_app_state, path_types::ItemId, state::AppConfig, ui_action::UI_RPC_FIELD};
 use tempfile::TempDir;
 use tokio::net::TcpListener;
 
@@ -63,9 +63,9 @@ async fn post_ui_record_vote_morphs_ranking_and_persists() {
         port: 0,
     };
     let state = create_app_state(cfg).await;
-    let groups = state.groups.read().await;
-    let group = groups.get("").expect("default scope group after replay");
-    let ranked = sorter2_server::ranking::ranked_items(group);
+    let tree = state.tree.read().await;
+    let root = tree.get(&ItemId::root()).expect("root node after replay");
+    let ranked = sorter2_server::ranking::ranked_items(&root.local_ranking);
     assert_eq!(ranked.len(), 2);
     assert_eq!(ranked[0].item.as_str(), "alpha");
 }
@@ -93,5 +93,5 @@ async fn post_ui_parse_query_redirects_to_subreddit() {
         .unwrap();
 
     assert!(body.contains("window.location.href"));
-    assert!(body.contains("/?sub=rust"));
+    assert!(body.contains("/?item=reddit.com/r/rust"));
 }