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:
[5ca518f6] url refactor

Side A — unified diff (full patch):
diff --git a/Cargo.lock b/Cargo.lock
index 67a09a3b54f778fa7e857fdd589c3ed9c92e1322..ad7e4fe6d4ba2f2b033916194c1ef1ed873f1d46 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1757,6 +1757,7 @@ name = "slug-types"
 version = "0.1.0"
 dependencies = [
  "serde",
+ "url",
 ]
 
 [[package]]
@@ -2272,6 +2273,7 @@ dependencies = [
  "idna",
  "percent-encoding",
  "serde",
+ "serde_derive",
 ]
 
 [[package]]
diff --git a/server/src/api/ui_html.rs b/server/src/api/ui_html.rs
index 606f7d6f97a4428efb90d1e0d544934c861fc4c5..cd3e0f0afd972d9ad9e7e4b92c5fa4c22bb8f620 100644
--- a/server/src/api/ui_html.rs
+++ b/server/src/api/ui_html.rs
@@ -270,10 +270,10 @@ fn post_redirect_location(room: &str, thread_tag: &str) -> String {
         format!("/t/{tag}")
     } else {
         let room = room.trim();
-        let Some((a, b)) = room.split_once('/') else {
+        let Some(seg) = slug_types::room_route_segment(room) else {
             return "/".to_string();
         };
-        format!("/r/{a}/{b}/t/{tag}")
+        format!("/r/{seg}/t/{tag}")
     }
 }
 
diff --git a/server/src/api/write_actor.rs b/server/src/api/write_actor.rs
index cb78d2f3f95b1bc163c1fb064d1d5f657e18000f..f9c3b8bd3fbf8fcb9c035e1a1572fef0b08fa8a9 100644
--- a/server/src/api/write_actor.rs
+++ b/server/src/api/write_actor.rs
@@ -19,13 +19,15 @@ use crate::{
 use super::auth::{issue_token_for_user, verify_token};
 use super::helpers::{now_ms, resolve_item};
 use super::validate::{normalize_room_and_thread, validate_ingest_document};
-use slug_types::RpcResult;
+use slug_types::{room_route_segment, RpcResult, ROOM_SHORT_ID_LEN};
 
 fn gen_short_id() -> String {
     use rand::Rng;
     const ALPHABET: &[u8] = b"0123456789abcdefghijklmnopqrstuvwxyz";
     let mut rng = rand::thread_rng();
-    (0..7).map(|_| ALPHABET[rng.gen_range(0..ALPHABET.len())] as char).collect()
+    (0..ROOM_SHORT_ID_LEN)
+        .map(|_| ALPHABET[rng.gen_range(0..ALPHABET.len())] as char)
+        .collect()
 }
 
 fn parse_capability(s: &str) -> Result<crate::events::ThreadCapability, String> {
@@ -55,8 +57,8 @@ async fn broadcast_web_refresh(state: &AppState, room_key: &str, thread_id: &str
     let feed_id = if room_key == "public" { "thread-feed" } else { "room-thread-feed" };
     let thread_url = if room_key == "public" {
         format!("/t/{thread_id}")
-    } else if let Some((short, slug)) = room_key.split_once('/') {
-        format!("/r/{short}/{slug}/t/{thread_id}")
+    } else if let Some(seg) = room_route_segment(room_key) {
+        format!("/r/{seg}/t/{thread_id}")
     } else {
         format!("/t/{thread_id}")
     };
@@ -78,8 +80,8 @@ async fn broadcast_web_refresh(state: &AppState, room_key: &str, thread_id: &str
     let js = builder.build();
     let mut path_prefixes = vec![if room_key == "public" {
         "/".to_string()
-    } else if let Some((short, slug)) = room_key.split_once('/') {
-        format!("/r/{short}/{slug}")
+    } else if let Some(seg) = room_route_segment(room_key) {
+        format!("/r/{seg}")
     } else {
         "/".to_string()
     }];
diff --git a/server/src/html/forum/nav.rs b/server/src/html/forum/nav.rs
index 0ee33d91160fc5542817b5e3e9ab4fee1d0e600f..48fe11e46731670874ff8b6b05baa6f09ae0b7e4 100644
--- a/server/src/html/forum/nav.rs
+++ b/server/src/html/forum/nav.rs
@@ -1,7 +1,8 @@
 use crate::canonical_path::canonicalize_item;
 use crate::reducer::ScopeId;
+use slug_types::room_route_segment;
 
-/// URL helpers for public `/t/…` and private room threads `/r/{short}/{slug}/t/…`.
+/// URL helpers for public `/t/…` and private room threads `/r/{short}{slug}/t/…`.
 #[derive(Clone)]
 pub struct ThreadNav {
     pub room_wire: String,
@@ -22,18 +23,15 @@ impl ThreadNav {
         }
     }
 
-    /// `room_id` wire form `shortid/slug`.
+    /// `room_id` wire form `shortid/slug` (HTTP uses [`slug_types::room_route_segment`]).
     pub(crate) fn from_room_id(room_id: &str) -> Option<Self> {
-        let (short, slug) = room_id.split_once('/')?;
-        if short.is_empty() || slug.is_empty() {
-            return None;
-        }
+        let room_seg = room_route_segment(room_id)?;
         Some(Self {
             room_wire: room_id.to_string(),
             scope: ScopeId::Room(room_id.to_string()),
-            room_path: format!("/r/{short}/{slug}"),
-            thread_path_prefix: format!("/r/{short}/{slug}/t"),
-            garden_path_prefix: format!("/r/{short}/{slug}/~"),
+            room_path: format!("/r/{room_seg}"),
+            thread_path_prefix: format!("/r/{room_seg}/t"),
+            garden_path_prefix: format!("/r/{room_seg}/~"),
         })
     }
 
diff --git a/server/src/html/forum/post_single.rs b/server/src/html/forum/post_single.rs
index c316f8f836df9d4ef9c05ebd9e54f699540e6d72..473747b3da3d4d7a54b5e0c63165d2533df643e1 100644
--- a/server/src/html/forum/post_single.rs
+++ b/server/src/html/forum/post_single.rs
@@ -93,12 +93,14 @@ pub async fn thread_post_view(
 
 pub async fn room_thread_post_view(
     State(state): State<AppState>,
-    Path((room_short, room_slug, tag, index_str)): Path<(String, String, String, String)>,
+    Path((room_key, tag, index_str)): Path<(String, String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
     uri: Uri,
 ) -> impl IntoResponse {
-    let room_id = format!("{room_short}/{room_slug}");
+    let Some(room_id) = slug_types::room_id_from_route_segment(&room_key) else {
+        return (StatusCode::NOT_FOUND, "bad room path").into_response();
+    };
     let reduced = state.reduced.read().await;
     let user = optional_principal(&headers, &jar, &reduced);
     if !user_can_view_room(&reduced, &room_id, user.as_deref()) {
diff --git a/server/src/html/forum/views.rs b/server/src/html/forum/views.rs
index be5df1745ef580891a167c23c3dd6c06f804f295..1ec421f84335cbfe7f9db775b73a8ed24b197174 100644
--- a/server/src/html/forum/views.rs
+++ b/server/src/html/forum/views.rs
@@ -183,16 +183,18 @@ pub async fn thread_view(
     thread_view_inner(state, tag, q, ThreadNav::public(), headers, jar, uri).await
 }
 
-/// Room thread — `/r/:short/:slug/t/:tag`
+/// Room thread — `/r/:room_key/t/:tag` (`room_key` = `{short}{slug}`).
 pub async fn room_thread_view(
     State(state): State<AppState>,
-    Path((room_short, room_slug, tag)): Path<(String, String, String)>,
+    Path((room_key, tag)): Path<(String, String)>,
     Query(q): Query<ThreadViewQuery>,
     headers: HeaderMap,
     jar: CookieJar,
     uri: Uri,
 ) -> impl IntoResponse {
-    let room_id = format!("{room_short}/{room_slug}");
+    let Some(room_id) = slug_types::room_id_from_route_segment(&room_key) else {
+        return (StatusCode::NOT_FOUND, "bad room path").into_response();
+    };
     let reduced = state.reduced.read().await;
     let user = optional_principal(&headers, &jar, &reduced);
     if !user_can_view_room(&reduced, &room_id, user.as_deref()) {
@@ -226,15 +228,17 @@ pub(super) fn room_not_found_page(jar: &CookieJar, uri: &Uri) -> impl IntoRespon
     (StatusCode::NOT_FOUND, Html(page.into_string()))
 }
 
-/// Private room index — `/r/:short/:slug`
+/// Private room index — `/r/:room_key`
 pub async fn room_page(
     State(state): State<AppState>,
-    Path((room_short, room_slug)): Path<(String, String)>,
+    Path(room_key): Path<String>,
     headers: HeaderMap,
     jar: CookieJar,
     uri: Uri,
 ) -> impl IntoResponse {
-    let room_id = format!("{room_short}/{room_slug}");
+    let Some(room_id) = slug_types::room_id_from_route_segment(&room_key) else {
+        return (StatusCode::NOT_FOUND, "room not found").into_response();
+    };
     let now = now_ms();
     let reduced = state.reduced.read().await;
     if !reduced.rooms.contains(&room_id) {
@@ -266,7 +270,10 @@ pub async fn room_page(
     let audit_cli = format!("npx slugsocial private {room_id} audit");
     drop(reduced);
 
-    let slug_display = room_slug.as_str();
+    let slug_display = room_id
+        .split_once('/')
+        .map(|(_, slug)| slug)
+        .unwrap_or(room_id.as_str());
     let page = layout(
         &format!("room {slug_display} — slug.social"),
         "view-thread",
diff --git a/server/src/html/garden.rs b/server/src/html/garden.rs
index 423f23fd8c9ad7b7f454d6ea7a9a7607a4c9c5b9..e615dd356bcf634232d85610c0a26235ead125fd 100644
--- a/server/src/html/garden.rs
+++ b/server/src/html/garden.rs
@@ -309,12 +309,14 @@ pub async fn external_ontology_path(
 
 pub async fn room_garden_index(
     State(state): State<AppState>,
-    Path((room_short, room_slug)): Path<(String, String)>,
+    Path(room_key): Path<String>,
     headers: HeaderMap,
     jar: CookieJar,
     uri: Uri,
 ) -> impl IntoResponse {
-    let room_id = format!("{room_short}/{room_slug}");
+    let Some(room_id) = slug_types::room_id_from_route_segment(&room_key) else {
+        return (StatusCode::NOT_FOUND, "bad room path").into_response();
+    };
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         return (StatusCode::NOT_FOUND, "bad room path").into_response();
     };
@@ -341,12 +343,14 @@ pub async fn room_garden_index(
 
 pub async fn room_external_garden_index(
     State(state): State<AppState>,
-    Path((room_short, room_slug)): Path<(String, String)>,
+    Path(room_key): Path<String>,
     headers: HeaderMap,
     jar: CookieJar,
     uri: Uri,
 ) -> impl IntoResponse {
-    let room_id = format!("{room_short}/{room_slug}");
+    let Some(room_id) = slug_types::room_id_from_route_segment(&room_key) else {
+        return (StatusCode::NOT_FOUND, "bad room path").into_response();
+    };
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         return (StatusCode::NOT_FOUND, "bad room path").into_response();
     };
@@ -416,12 +420,14 @@ pub async fn room_external_garden_index(
 
 pub async fn room_external_ontology_path(
     State(state): State<AppState>,
-    Path((room_short, room_slug, path)): Path<(String, String, String)>,
+    Path((room_key, path)): Path<(String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
     uri: Uri,
 ) -> impl IntoResponse {
-    let room_id = format!("{room_short}/{room_slug}");
+    let Some(room_id) = slug_types::room_id_from_route_segment(&room_key) else {
+        return (StatusCode::NOT_FOUND, "bad room path").into_response();
+    };
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         return (StatusCode::NOT_FOUND, "bad room path").into_response();
     };
@@ -442,12 +448,14 @@ pub async fn room_external_ontology_path(
 
 pub async fn room_ontology_path(
     State(state): State<AppState>,
-    Path((room_short, room_slug, path)): Path<(String, String, String)>,
+    Path((room_key, path)): Path<(String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
     uri: Uri,
 ) -> impl IntoResponse {
-    let room_id = format!("{room_short}/{room_slug}");
+    let Some(room_id) = slug_types::room_id_from_route_segment(&room_key) else {
+        return (StatusCode::NOT_FOUND, "bad room path").into_response();
+    };
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         return (StatusCode::NOT_FOUND, "bad room path").into_response();
     };
diff --git a/server/src/html/search.rs b/server/src/html/search.rs
index 43e6ebf36cf0fe72c96f0f9d850bea51ac094c43..f01732f7edb32c68fcc10c39545c8f56476adb27 100644
--- a/server/src/html/search.rs
+++ b/server/src/html/search.rs
@@ -351,8 +351,8 @@ fn render_search_results(results: &SearchResults, query: &str) -> Markup {
                     ul class="search-posts" {
                         @for r in &results.posts {
                             @let (post_href, post_label) = if let Some((room, tag)) = r.thread.split_once("/#") {
-                                if let Some((short, slug)) = room.split_once('/') {
-                                    (format!("/r/{short}/{slug}/t/{tag}"), format!("{room}/#{tag}"))
+                                if let Some(seg) = slug_types::room_route_segment(room) {
+                                    (format!("/r/{seg}/t/{tag}"), format!("{room}/#{tag}"))
                                 } else {
                                     ("/".to_string(), r.thread.clone())
                                 }
diff --git a/server/src/lib.rs b/server/src/lib.rs
index 9e69c3f4a153527caa77b00ad101aca94b425995..71032f9a0b556097d90f3b403c677e0c86429ee4 100644
--- a/server/src/lib.rs
+++ b/server/src/lib.rs
@@ -79,30 +79,30 @@ pub fn create_app(state: AppState) -> Router {
         .route("/~/*path", get(crate::html::ontology_path))
         .route("/-", get(crate::html::external_garden_index))
         .route("/-/*path", get(crate::html::external_ontology_path))
-        .route("/r/:room_short/:room_slug/~", get(crate::html::room_garden_index))
+        .route("/r/:room_key/~", get(crate::html::room_garden_index))
         .route(
-            "/r/:room_short/:room_slug/~/*path",
+            "/r/:room_key/~/*path",
             get(crate::html::room_ontology_path),
         )
         .route(
-            "/r/:room_short/:room_slug/-",
+            "/r/:room_key/-",
             get(crate::html::room_external_garden_index),
         )
         .route(
-            "/r/:room_short/:room_slug/-/*path",
+            "/r/:room_key/-/*path",
             get(crate::html::room_external_ontology_path),
         )
         .route("/t/:tag/:index", get(crate::html::thread_post_view))
         .route("/t/:tag", get(crate::html::thread_view))
         .route(
-            "/r/:room_short/:room_slug/t/:thread_tag/:index",
+            "/r/:room_key/t/:thread_tag/:index",
             get(crate::html::room_thread_post_view),
         )
         .route(
-            "/r/:room_short/:room_slug/t/:thread_tag",
+            "/r/:room_key/t/:thread_tag",
             get(crate::html::room_thread_view),
         )
-        .route("/r/:room_short/:room_slug", get(crate::html::room_page))
+        .route("/r/:room_key", get(crate::html::room_page))
         .route("/join/:token", get(api::get_join_invite))
         .route("/auth/login", get(api::get_auth_login))
         .route("/auth/callback", get(api::get_auth_callback))
diff --git a/server/tests/integration.rs b/server/tests/integration.rs
index 515c691d04ef3f1f4bdfa8ee911360a43fd2b26e..feb73d475b3fc635d7f16c329d4600718c7472ba 100644
--- a/server/tests/integration.rs
+++ b/server/tests/integration.rs
@@ -1,4 +1,5 @@
 use sha2::{Digest, Sha256};
+use slug_types::room_route_segment;
 use slugsocial_server::{
     event_log::EventLog,
     events::{Event, TokenIssued, UserRegistered},
@@ -607,7 +608,7 @@ async fn test_private_room_thread_urls_use_t_segment() {
         .as_str()
         .unwrap()
         .to_string();
-    let (room_short, room_slug) = room_id.split_once('/').unwrap();
+    let room_seg = room_route_segment(&room_id).unwrap();
 
     let rpc = ui_post_ingest_rpc(&room_id, "main-thread", "private post via web");
     let post = client
@@ -626,7 +627,7 @@ async fn test_private_room_thread_urls_use_t_segment() {
         Some("text/javascript; charset=utf-8")
     );
     let post_js = post.text().await.unwrap();
-    let location = format!("/r/{room_short}/{room_slug}/t/main-thread");
+    let location = format!("/r/{room_seg}/t/main-thread");
     assert!(post_js.contains(&format!("window.location = {:?};", location)));
     assert!(post_js.contains("#room-thread-feed"));
     assert!(post_js.contains("#thread-feed-region"));
@@ -665,7 +666,7 @@ async fn test_private_room_post_links_use_private_garden_routes() {
         .as_str()
         .unwrap()
         .to_string();
-    let (room_short, room_slug) = room_id.split_once('/').unwrap();
+    let room_seg = room_route_segment(&room_id).unwrap();
 
     let rpc = ui_post_ingest_rpc(
         &room_id,
@@ -682,18 +683,18 @@ async fn test_private_room_post_links_use_private_garden_routes() {
     assert_eq!(post.status(), reqwest::StatusCode::OK);
 
     let thread_page = client
-        .get(format!("http://{addr}/r/{room_short}/{room_slug}/t/garden-thread"))
+        .get(format!("http://{addr}/r/{room_seg}/t/garden-thread"))
         .header("Authorization", format!("Bearer {bearer}"))
         .send()
         .await
         .unwrap();
     assert!(thread_page.status().is_success());
     let body = thread_page.text().await.unwrap();
-    assert!(body.contains(&format!("/r/{room_short}/{room_slug}/~/secret/item")));
+    assert!(body.contains(&format!("/r/{room_seg}/~/secret/item")));
     assert!(!body.contains("href=\"/~/secret/item\""));
 
     let garden_page = client
-        .get(format!("http://{addr}/r/{room_short}/{room_slug}/~/secret/item"))
+        .get(format!("http://{addr}/r/{room_seg}/~/secret/item"))
         .header("Authorization", format!("Bearer {bearer}"))
         .send()
         .await
@@ -701,7 +702,7 @@ async fn test_private_room_post_links_use_private_garden_routes() {
     assert!(garden_page.status().is_success());
     let garden_body = garden_page.text().await.unwrap();
     assert!(garden_body.contains("classified"));
-    assert!(garden_body.contains(&format!("/r/{room_short}/{room_slug}/t/garden-thread")));
+    assert!(garden_body.contains(&format!("/r/{room_seg}/t/garden-thread")));
 }
 
 #[tokio::test]
@@ -726,7 +727,7 @@ async fn test_private_room_garden_root_lists_top_level_tilde_children() {
         .as_str()
         .unwrap()
         .to_string();
-    let (room_short, room_slug) = room_id.split_once('/').unwrap();
+    let room_seg = room_route_segment(&room_id).unwrap();
 
     let rpc = ui_post_ingest_rpc(
         &room_id,
@@ -743,7 +744,7 @@ async fn test_private_room_garden_root_lists_top_level_tilde_children() {
     assert_eq!(post.status(), reqwest::StatusCode::OK);
 
     let root_page = client
-        .get(format!("http://{addr}/r/{room_short}/{room_slug}/~"))
+        .get(format!("http://{addr}/r/{room_seg}/~"))
         .header("Authorization", format!("Bearer {bearer}"))
         .send()
         .await
@@ -782,10 +783,10 @@ async fn test_empty_private_room_garden_returns_404() {
         .as_str()
         .unwrap()
         .to_string();
-    let (room_short, room_slug) = room_id.split_once('/').unwrap();
+    let room_seg = room_route_segment(&room_id).unwrap();
 
     let root = client
-        .get(format!("http://{addr}/r/{room_short}/{room_slug}/~"))
+        .get(format!("http://{addr}/r/{room_seg}/~"))
         .header("Authorization", format!("Bearer {bearer}"))
         .send()
         .await
@@ -896,8 +897,8 @@ async fn test_sse_stream_emits_evalable_js_after_post() {
         .as_str()
         .unwrap()
         .to_string();
-    let (room_short, room_slug) = room_id.split_once('/').unwrap();
-    let room_path = format!("/r/{room_short}/{room_slug}");
+    let room_seg = room_route_segment(&room_id).unwrap();
+    let room_path = format!("/r/{room_seg}");
 
     let sse_resp = client
         .get(format!("http://{addr}/sse?path={}", urlencoding::encode(&room_path)))
diff --git a/test/browser_room_delete.clj b/test/browser_room_delete.clj
index 833e3f8aa7f850b60ee59742736143cbf101a07d..764ecaa674798a61c1ffca3859f2a56a91a0e97e 100644
--- a/test/browser_room_delete.clj
+++ b/test/browser_room_delete.clj
@@ -54,7 +54,7 @@
            room-id (get-in create-json ["results" 0 "result" "RoomCreated" "room_id"])
            _ (is (string? room-id) "room id present")
            [room-short room-slug] (str/split room-id #"/" 2)
-           room-path (str "/r/" room-short "/" room-slug)]
+           room-path (str "/r/" room-short room-slug)]
        (core/with-playwright [pw]
          (core/with-browser [browser (core/launch-chromium pw {:headless true :channel "chrome"})]
            (core/with-context [ctx (core/new-context browser)]
diff --git a/test/browser_sse.clj b/test/browser_sse.clj
index 8bb064dbc2dc0feb6caaa67f520a461645958277..678399b79f78ff48b5e77342fa21e69992393834 100644
--- a/test/browser_sse.clj
+++ b/test/browser_sse.clj
@@ -77,7 +77,7 @@
                   (login-user! bob-pg base-url "bob")
 
                    (let [[room-short room-slug] (str/split room-id #"/" 2)
-                         room-url (str base-url "/r/" room-short "/" room-slug)
+                         room-url (str base-url "/r/" room-short room-slug)
                          thread-url (str room-url "/t/sse-thread")]
                     ;; Object under test: slug_ui.js intercepts POST /ui, evals JS, morphs
                     ;; #new-thread-ui-slot (expand compose), then post_ingest redirects to thread.
diff --git a/test/walkthrough_fixture.clj b/test/walkthrough_fixture.clj
index a487ff1ef8548580577914fb33f321586859c9af..f7eb1cacca0317129e9baf68fa4f4e33356ad70f 100644
--- a/test/walkthrough_fixture.clj
+++ b/test/walkthrough_fixture.clj
@@ -88,9 +88,9 @@
      :room {:id room-id
             :short room-short
             :slug room-slug
-            :url (str base-url "/r/" room-short "/" room-slug)
-            :thread_url (str base-url "/r/" room-short "/" room-slug "/t/walkthrough-thread")
-            :garden_url (str base-url "/r/" room-short "/" room-slug "/~/secret/item")}}))
+            :url (str base-url "/r/" room-short room-slug)
+            :thread_url (str base-url "/r/" room-short room-slug "/t/walkthrough-thread")
+            :garden_url (str base-url "/r/" room-short room-slug "/~/secret/item")}}))
 
 (defn- rebase-fixture-summary [saved current-base-url current-google-url current-data-dir]
   (let [inner (:summary saved)
@@ -103,9 +103,9 @@
            :data_dir (str current-data-dir)
            :summary (assoc inner
                            :room (assoc room
-                                         :url (str current-base-url "/r/" rs "/" lg)
-                                         :thread_url (str current-base-url "/r/" rs "/" lg "/t/walkthrough-thread")
-                                         :garden_url (str current-base-url "/r/" rs "/" lg "/~/secret/item"))))))
+                                         :url (str current-base-url "/r/" rs lg)
+                                         :thread_url (str current-base-url "/r/" rs lg "/t/walkthrough-thread")
+                                         :garden_url (str current-base-url "/r/" rs lg "/~/secret/item"))))))
 
 (defn- fixture-log-present? [data-dir]
   (let [p (fs/path data-dir "events.jsonl")]
diff --git a/types/Cargo.toml b/types/Cargo.toml
index 1ed06d483ac7c126516bce27f90e7639c2dfe370..5dc3becf238f23243313dff0484c682a7b225737 100644
--- a/types/Cargo.toml
+++ b/types/Cargo.toml
@@ -5,3 +5,4 @@ edition = "2021"
 
 [dependencies]
 serde = { version = "1.0", features = ["derive"] }
+url = { version = "2.5", features = ["serde"] }
diff --git a/types/src/lib.rs b/types/src/lib.rs
index fce1b5fa5e259a4b86a11cb4d4f7cc9bec3a0aa1..516cf935f15fca97081b39b988da5be894c67725 100644
--- a/types/src/lib.rs
+++ b/types/src/lib.rs
@@ -1,5 +1,7 @@
 use serde::{Deserialize, Serialize};
 
+pub mod room_route;
+pub mod url_normalize;
 pub mod paths;
 pub mod timeago;
 
@@ -8,6 +10,8 @@ pub use paths::{
     CanonicalItemUrl, ForumThreadUrl, GardenItemUrl, RelativePath, SLUG_TILDE_ONTOLOGY_ROOT,
     TildeHttpPathTail, TildeOntologyPath, TildePath, tilde_http_path_to_canonical,
 };
+pub use room_route::{room_id_from_route_segment, room_route_segment, ROOM_SHORT_ID_LEN};
+pub use url_normalize::normalize_http_identity_url;
 
 /// Max characters returned for a garden item body unless `full=true` / `--full` (API + CLI).
 pub const MAX_ITEM_BODY_PREVIEW_CHARS: usize = 100_000;
@@ -657,3 +661,6 @@ pub struct VoteResponse {
     pub ranking: Vec<RankRow>,
     pub next: NextMoves,
 }
+
+#[cfg(test)]
+mod url_identity_tests;
diff --git a/types/src/paths.rs b/types/src/paths.rs
index 8971f599a7ebcf399f60c306d35ee28d0f581194..98787a5fb481a1599556564bbbbd1d54dc693fc3 100644
--- a/types/src/paths.rs
+++ b/types/src/paths.rs
@@ -5,7 +5,7 @@
 //!
 //! - **[`canonicalize_item`] / [`CanonicalItemUrl`]** — graph storage key and DSL form; tilde
 //!   ontology root is always [`SLUG_TILDE_ONTOLOGY_ROOT`] (no `…/~/` trailing slash only).
-//! - **[`TildeHttpPathTail`]** — capture from `GET /~/*path` or `…/r/…/~/…` (the `*path` segment).
+//! - **[`TildeHttpPathTail`]** — capture from `GET /~/*path` or `…/r/{short}{slug}/~/…` (the `*path` segment).
 //! - **`-/…` wire form** — external items; see [`canonicalize_item`] dash branch.
 //! - **[`GardenItemUrl`], [`ForumThreadUrl`]** — JSON / browser href surfaces.
 
@@ -15,6 +15,9 @@ use std::ops::Deref;
 
 use serde::{Deserialize, Serialize};
 
+use crate::room_route::room_route_segment;
+use crate::url_normalize::{host_preserves_dash_path_case, normalize_http_identity_url};
+
 // ---------------------------------------------------------------------------
 // Slug tilde ontology (single storage form for `~/`)
 // ---------------------------------------------------------------------------
@@ -41,6 +44,29 @@ pub fn canonicalize_tag(input: &str) -> String {
     input.trim().trim_start_matches('#').to_lowercase()
 }
 
+fn finalize_external_identity_url(s: String) -> String {
+    if s.starts_with("https://slug.social/") {
+        return s;
+    }
+    let normalized = normalize_http_identity_url(&s).unwrap_or_else(|| s.clone());
+    strip_redundant_root_slash(&normalized).unwrap_or(normalized)
+}
+
+/// `url::Url` serializes bare hosts with a `/` path; we keep host-only items slash-free for stable
+/// keys matching the pre-normalizer spellings.
+fn strip_redundant_root_slash(s: &str) -> Option<String> {
+    let u = url::Url::parse(s).ok()?;
+    if u.path() == "/" && u.query().is_none() && u.fragment().is_none() {
+        let scheme = u.scheme();
+        let host = u.host_str()?;
+        return Some(match u.port() {
+            Some(p) => format!("{scheme}://{host}:{p}"),
+            None => format!("{scheme}://{host}"),
+        });
+    }
+    None
+}
+
 /// Ontology item reference → canonical absolute URL on the slug host.
 pub fn canonicalize_item(input: &str) -> String {
     let s = input.trim();
@@ -57,8 +83,9 @@ pub fn canonicalize_item(input: &str) -> String {
         if host.is_empty() {
             return String::new();
         }
+        let preserve_case = host_preserves_dash_path_case(&host);
         return if tail.is_empty() {
-            format!("https://{}", host)
+            finalize_external_identity_url(format!("https://{}", host))
         } else {
             let path = tail
                 .trim_start_matches('/')
@@ -68,33 +95,35 @@ pub fn canonicalize_item(input: &str) -> String {
                     let t = seg.trim();
                     if t.is_empty() {
                         None
+                    } else if preserve_case {
+                        Some(t.to_string())
                     } else {
                         Some(t.to_lowercase())
                     }
                 })
                 .collect::<Vec<_>>()
                 .join("/");
-            format!("https://{}/{}", host, path)
+            finalize_external_identity_url(format!("https://{}/{}", host, path))
         };
     }
 
     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);
+        return finalize_external_identity_url(if tail.is_empty() {
+            format!("https://{}", host)
         } else {
-            return format!("https://{}/{}", host, tail);
-        }
+            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);
+        return finalize_external_identity_url(if tail.is_empty() {
+            format!("http://{}", host)
         } else {
-            return format!("http://{}/{}", host, tail);
-        }
+            format!("http://{}/{}", host, tail)
+        });
     }
 
     let is_tilde = s.starts_with("~/");
@@ -319,7 +348,7 @@ impl CanonicalItemUrl {
     }
 }
 
-/// HTTP route capture: path segment after `~/` in `GET /~/*path` or `…/r/…/~/…` (empty = ontology root).
+/// HTTP route capture: path segment after `~/` in `GET /~/*path` or `…/r/{short}{slug}/~/…` (empty = ontology root).
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct TildeHttpPathTail(pub String);
 
@@ -506,12 +535,9 @@ fn garden_href_string(item: &str, room_wire: &str) -> String {
     if room.is_empty() || room == "public" {
         return api_path_or_url(item);
     }
-    let Some((short, slug)) = room.split_once('/') else {
+    let Some(room_seg) = room_route_segment(room) 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);
     };
@@ -520,19 +546,19 @@ fn garden_href_string(item: &str, room_wire: &str) -> String {
     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}/~")
+            format!("https://slug.social/r/{room_seg}/~")
         } else {
-            format!("https://slug.social/r/{short}/{slug}/~/{}", tail)
+            format!("https://slug.social/r/{room_seg}/~/{}", tail)
         };
     }
     if item_norm == root_norm {
-        return format!("https://slug.social/r/{short}/{slug}/~");
+        return format!("https://slug.social/r/{room_seg}/~");
     }
     // External http(s) items use the same `/-/…` namespace under the room garden.
     if c.as_str().starts_with("https://") || c.as_str().starts_with("http://") {
         let tail = c.display_path();
         let tail = tail.strip_prefix("-/").unwrap_or(tail.as_str());
-        return format!("https://slug.social/r/{short}/{slug}/-/{tail}");
+        return format!("https://slug.social/r/{room_seg}/-/{tail}");
     }
     api_path_or_url(item)
 }
@@ -556,12 +582,8 @@ impl ForumThreadUrl {
         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 if let Some(room_seg) = room_route_segment(room) {
+            format!("https://slug.social/r/{room_seg}/t/{tag}")
         } else {
             format!("https://slug.social/t/{tag}")
         })
@@ -706,7 +728,7 @@ mod tests {
     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"
+            "https://slug.social/r/9ab12cdmy-room/~/topic/x"
         );
     }
 
@@ -714,11 +736,11 @@ mod tests {
     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/~"
+            "https://slug.social/r/9ab12cdmy-room/~"
         );
         assert_eq!(
             GardenItemUrl::from_storage_str("https://slug.social/~/", "9ab12cd/my-room").as_str(),
-            "https://slug.social/r/9ab12cd/my-room/~"
+            "https://slug.social/r/9ab12cdmy-room/~"
         );
     }
 
@@ -727,7 +749,7 @@ mod tests {
         let u = "https://example.com/z";
         assert_eq!(
             GardenItemUrl::from_storage_str(u, "9ab12cd/my-room").as_str(),
-            "https://slug.social/r/9ab12cd/my-room/-/example.com/z"
+            "https://slug.social/r/9ab12cdmy-room/-/example.com/z"
         );
     }
 
@@ -739,7 +761,19 @@ mod tests {
         );
         assert_eq!(
             ForumThreadUrl::from_room_tag("9ab12cd/my-room", "#debate").as_str(),
-            "https://slug.social/r/9ab12cd/my-room/t/debate"
+            "https://slug.social/r/9ab12cdmy-room/t/debate"
+        );
+    }
+
+    #[test]
+    fn canonicalize_youtube_short_links() {
+        assert_eq!(
+            canonicalize_item("https://youtu.be/dQw4w9WgXcQ"),
+            "https://www.youtube.com/watch?v=dQw4w9WgXcQ"
+        );
+        assert_eq!(
+            canonicalize_item("-/youtu.be/dQw4w9WgXcQ"),
+            "https://www.youtube.com/watch?v=dQw4w9WgXcQ"
         );
     }
 
diff --git a/types/src/room_route.rs b/types/src/room_route.rs
new file mode 100644
index 0000000000000000000000000000000000000000..4f4780c88e30f2b28e2cfcd7aee713d39dbd1c66
--- /dev/null
+++ b/types/src/room_route.rs
@@ -0,0 +1,56 @@
+//! HTTP path encoding for private rooms: `/r/{short}{slug}` (short is fixed width).
+
+/// Byte length of the random `short` segment in `short/slug` room ids.
+/// Must match room creation (`gen_short_id`) and [`super::paths`][] URL builders.
+pub const ROOM_SHORT_ID_LEN: usize = 7;
+
+/// `ab12cde/my-room` → `ab12cdemy-room` for a single `/r/…` path segment.
+pub fn room_route_segment(room_id: &str) -> Option<String> {
+    let (short, slug) = room_id.split_once('/')?;
+    if short.len() != ROOM_SHORT_ID_LEN || short.is_empty() || slug.is_empty() {
+        return None;
+    }
+    if !short
+        .bytes()
+        .all(|b| matches!(b, b'0'..=b'9' | b'a'..=b'z'))
+    {
+        return None;
+    }
+    Some(format!("{short}{slug}"))
+}
+
+/// `/r/{short}{slug}` path segment → `short/slug` wire id (inverse of [`room_route_segment`]).
+pub fn room_id_from_route_segment(seg: &str) -> Option<String> {
+    if seg.len() <= ROOM_SHORT_ID_LEN {
+        return None;
+    }
+    let (short, slug) = seg.split_at(ROOM_SHORT_ID_LEN);
+    if short.is_empty() || slug.is_empty() {
+        return None;
+    }
+    if !short
+        .bytes()
+        .all(|b| matches!(b, b'0'..=b'9' | b'a'..=b'z'))
+    {
+        return None;
+    }
+    Some(format!("{short}/{slug}"))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn round_trip_room_segment() {
+        let id = "9ab12cd/my-room";
+        let seg = room_route_segment(id).unwrap();
+        assert_eq!(seg, "9ab12cdmy-room");
+        assert_eq!(room_id_from_route_segment(&seg).as_deref(), Some(id));
+    }
+
+    #[test]
+    fn too_short_segment_rejected() {
+        assert!(room_id_from_route_segment("9ab12cd").is_none());
+    }
+}
diff --git a/types/src/url_identity_tests.rs b/types/src/url_identity_tests.rs
new file mode 100644
index 0000000000000000000000000000000000000000..e2ff0a9a64a88049e31f20979c703777df6a9b65
--- /dev/null
+++ b/types/src/url_identity_tests.rs
@@ -0,0 +1,126 @@
+//! How `url::Url` behaves as `HashMap` keys (`Eq` + `Hash`).
+//!
+//! If `ItemId::External` stores `Url`, these tests are the contract you are buying into
+//! (or the baseline before you add a custom normalization layer).
+
+use std::collections::HashMap;
+use std::hash::{Hash, Hasher};
+use url::Url;
+
+fn hash_one(url: &Url) -> u64 {
+    let mut h = std::collections::hash_map::DefaultHasher::new();
+    url.hash(&mut h);
+    h.finish()
+}
+
+#[test]
+fn identical_parse_strings_are_eq_and_share_hash_bucket() {
+    let a = Url::parse("https://example.com/path").unwrap();
+    let b = Url::parse("https://example.com/path").unwrap();
+    assert_eq!(a, b);
+    assert_eq!(hash_one(&a), hash_one(&b));
+
+    let mut m: HashMap<Url, u32> = HashMap::new();
+    m.insert(a, 1);
+    *m.entry(b).or_default() += 10;
+    assert_eq!(m.len(), 1);
+    assert_eq!(m[&Url::parse("https://example.com/path").unwrap()], 11);
+}
+
+#[test]
+fn host_is_ascii_lowercase_in_eq() {
+    let lower = Url::parse("https://examplE.com/").unwrap();
+    let upper = Url::parse("https://EXAMPLE.com/").unwrap();
+    assert_eq!(lower, upper);
+    assert_eq!(hash_one(&lower), hash_one(&upper));
+}
+
+#[test]
+fn path_space_normalizes_to_percent_encoding_so_forms_merge() {
+    let encoded = Url::parse("https://example.com/a%20b").unwrap();
+    let decoded = Url::parse("https://example.com/a b").unwrap();
+    // Parser normalizes both to the same internal path (`/a%20b`).
+    assert_eq!(encoded, decoded);
+    assert_eq!(hash_one(&encoded), hash_one(&decoded));
+
+    let mut m: HashMap<Url, &str> = HashMap::new();
+    m.insert(encoded, "first");
+    assert_eq!(m.insert(decoded, "second"), Some("first"));
+    assert_eq!(m.len(), 1);
+    assert_eq!(m.values().next().copied(), Some("second"));
+}
+
+#[test]
+fn encoded_slash_in_segment_stays_distinct_from_real_path_separator() {
+    let encoded = Url::parse("https://example.com/a%2Fb").unwrap();
+    let real_slash = Url::parse("https://example.com/a/b").unwrap();
+    assert_ne!(encoded, real_slash);
+    assert_ne!(hash_one(&encoded), hash_one(&real_slash));
+}
+
+#[test]
+fn trailing_slash_on_path_is_significant_for_eq() {
+    let with_slash = Url::parse("https://example.com/foo/").unwrap();
+    let no_slash = Url::parse("https://example.com/foo").unwrap();
+    assert_ne!(with_slash, no_slash);
+    assert_ne!(hash_one(&with_slash), hash_one(&no_slash));
+}
+
+#[test]
+fn default_http_port_80_is_normalized_in_representation() {
+    let explicit = Url::parse("http://example.com:80/").unwrap();
+    let implicit = Url::parse("http://example.com/").unwrap();
+    assert_eq!(explicit, implicit);
+    assert_eq!(hash_one(&explicit), hash_one(&implicit));
+}
+
+#[test]
+fn default_https_port_443_is_normalized() {
+    let explicit = Url::parse("https://example.com:443/foo").unwrap();
+    let implicit = Url::parse("https://example.com/foo").unwrap();
+    assert_eq!(explicit, implicit);
+}
+
+#[test]
+fn non_default_port_is_part_of_identity() {
+    let a = Url::parse("https://example.com:444/").unwrap();
+    let b = Url::parse("https://example.com:445/").unwrap();
+    assert_ne!(a, b);
+}
+
+#[test]
+fn empty_path_vs_slash_only_path_may_differ() {
+    let root = Url::parse("https://example.com").unwrap();
+    let slash = Url::parse("https://example.com/").unwrap();
+    // Both serialize to `https://example.com/` in practice for this crate — verify.
+    assert_eq!(root, slash, "document: root and trailing-slash-only merge for this parser");
+}
+
+#[test]
+fn scheme_case_is_normalized_to_lowercase() {
+    let lower = Url::parse("https://example.com/").unwrap();
+    let upper = Url::parse("HTTPS://example.com/").unwrap();
+    assert_eq!(lower, upper);
+}
+
+#[test]
+fn fragment_is_part_of_eq_and_hash() {
+    let no_frag = Url::parse("https://example.com/a").unwrap();
+    let frag = Url::parse("https://example.com/a#section").unwrap();
+    assert_ne!(
+        no_frag, frag,
+        "#fragment is included in PartialEq — anchors are different HashMap keys"
+    );
+    assert_ne!(hash_one(&no_frag), hash_one(&frag));
+}
+
+#[test]
+fn query_order_and_encoding_can_split_identity() {
+    let a = Url::parse("https://example.com/?b=2&a=1").unwrap();
+    let b = Url::parse("https://example.com/?a=1&b=2").unwrap();
+    assert_ne!(a, b, "query pairs order is preserved in serialization");
+
+    let plus = Url::parse("https://example.com/?q=a+b").unwrap();
+    let encoded = Url::parse("https://example.com/?q=a%20b").unwrap();
+    assert_ne!(plus, encoded, "space as + vs %20 — different keys unless normalized");
+}
diff --git a/types/src/url_normalize.rs b/types/src/url_normalize.rs
new file mode 100644
index 0000000000000000000000000000000000000000..d5bc913f33ad29cd0cd1c7158e28e4fefdbf5f5d
--- /dev/null
+++ b/types/src/url_normalize.rs
@@ -0,0 +1,234 @@
+//! Normalization for external `http(s)://` item identity (not slug tilde ontology).
+//!
+//! Policy (intentional, extend here as new domains need treatment):
+//! - Query pairs sorted lexicographically by **lowercased** key, then value.
+//! - YouTube family → stable `www.youtube.com` shapes where possible.
+
+use url::Url;
+
+/// Whether `-/` → `https://…` path segments should keep original casing (YouTube video IDs are
+/// case-sensitive).
+pub(crate) fn host_preserves_dash_path_case(host: &str) -> bool {
+    let h = host.trim().to_ascii_lowercase();
+    let h = h.strip_prefix("www.").unwrap_or(h.as_str());
+    matches!(
+        h,
+        "youtu.be" | "youtube.com" | "m.youtube.com" | "music.youtube.com"
+    )
+}
+
+/// Normalize external http(s) URLs for stable [`super::paths::canonicalize_item`] output.
+pub fn normalize_http_identity_url(s: &str) -> Option<String> {
+    let mut u = Url::parse(s).ok()?;
+    if !matches!(u.scheme(), "http" | "https") {
+        return None;
+    }
+    rewrite_youtube(&mut u);
+    sort_query_pairs(&mut u);
+    Some(u.to_string())
+}
+
+fn base_host(host: &str) -> String {
+    let lower = host.to_ascii_lowercase();
+    lower
+        .strip_prefix("www.")
+        .unwrap_or(lower.as_str())
+        .to_string()
+}
+
+fn rewrite_youtube(u: &mut Url) {
+    let Some(host_raw) = u.host_str() else {
+        return;
+    };
+    let base = base_host(host_raw);
+    let path = u.path().to_string();
+
+    match base.as_str() {
+        "youtu.be" => {
+            let id = path.trim_start_matches('/').split('/').next().unwrap_or("").to_string();
+            if id.is_empty() {
+                return;
+            }
+            let saved: Vec<(String, String)> = u.query_pairs().into_owned().collect();
+            let Ok(mut out) = Url::parse(&format!("https://www.youtube.com/watch?v={id}")) else {
+                return;
+            };
+            {
+                let mut q = out.query_pairs_mut();
+                for (k, v) in saved {
+                    if k.eq_ignore_ascii_case("v") {
+                        continue;
+                    }
+                    q.append_pair(&k, &v);
+                }
+            }
+            *u = out;
+        }
+        "youtube.com" | "m.youtube.com" => {
+            if base == "m.youtube.com" {
+                let _ = u.set_host(Some("www.youtube.com"));
+            }
+            if path.starts_with("/embed/") {
+                let id = path
+                    .strip_prefix("/embed/")
+                    .unwrap_or("")
+                    .trim_matches('/')
+                    .split('/')
+                    .next()
+                    .unwrap_or("")
+                    .to_string();
+                if id.is_empty() {
+                    return;
+                }
+                let saved: Vec<(String, String)> = u.query_pairs().into_owned().collect();
+                let Ok(mut out) = Url::parse(&format!("https://www.youtube.com/watch?v={id}"))
+                else {
+                    return;
+                };
+                {
+                    let mut q = out.query_pairs_mut();
+                    for (k, v) in saved {
+                        if k.eq_ignore_ascii_case("v") {
+                            continue;
+                        }
+                        q.append_pair(&k, &v);
+                    }
+                }
+                *u = out;
+                return;
+            }
+            if path.starts_with("/v/") {
+                let id = path
+                    .strip_prefix("/v/")
+                    .unwrap_or("")
+                    .trim_matches('/')
+                    .split('/')
+                    .next()
+                    .unwrap_or("")
+                    .to_string();
+                if id.is_empty() {
+                    return;
+                }
+                let saved: Vec<(String, String)> = u.query_pairs().into_owned().collect();
+                let Ok(mut out) = Url::parse(&format!("https://www.youtube.com/watch?v={id}"))
+                else {
+                    return;
+                };
+                {
+                    let mut q = out.query_pairs_mut();
+                    for (k, v) in saved {
+                        if k.eq_ignore_ascii_case("v") {
+                            continue;
+                        }
+                        q.append_pair(&k, &v);
+                    }
+                }
+                *u = out;
+                return;
+            }
+            if path.starts_with("/watch") {
+                let _ = u.set_host(Some("www.youtube.com"));
+                return;
+            }
+            if path.starts_with("/shorts/") {
+                let id = path
+                    .strip_prefix("/shorts/")
+                    .unwrap_or("")
+                    .trim_matches('/')
+                    .split('/')
+                    .next()
+                    .unwrap_or("")
+                    .to_string();
+                if id.is_empty() {
+                    return;
+                }
+                let saved: Vec<(String, String)> = u.query_pairs().into_owned().collect();
+                let Ok(mut out) = Url::parse(&format!("https://www.youtube.com/shorts/{id}"))
+                else {
+                    return;
+                };
+                {
+                    let mut q = out.query_pairs_mut();
+                    for (k, v) in saved {
+                        q.append_pair(&k, &v);
+                    }
+                }
+                *u = out;
+                return;
+            }
+            let _ = u.set_host(Some("www.youtube.com"));
+        }
+        "music.youtube.com" => {}
+        _ => {}
+    }
+}
+
+fn sort_query_pairs(u: &mut Url) {
+    let pairs: Vec<(String, String)> = u.query_pairs().into_owned().collect();
+    if pairs.is_empty() {
+        u.set_query(None);
+        return;
+    }
+    let mut pairs = pairs;
+    pairs.sort_by(|a, b| {
+        a.0.to_ascii_lowercase()
+            .cmp(&b.0.to_ascii_lowercase())
+            .then_with(|| a.1.cmp(&b.1))
+    });
+    u.set_query(None);
+    {
+        let mut q = u.query_pairs_mut();
+        for (k, v) in pairs {
+            q.append_pair(&k, &v);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn youtube_youtu_be_to_watch() {
+        assert_eq!(
+            normalize_http_identity_url("https://youtu.be/dQw4w9WgXcQ").as_deref(),
+            Some("https://www.youtube.com/watch?v=dQw4w9WgXcQ")
+        );
+    }
+
+    #[test]
+    fn youtube_watch_query_sorted() {
+        assert_eq!(
+            normalize_http_identity_url("https://youtube.com/watch?v=Z&a=1&b=2").as_deref(),
+            Some("https://www.youtube.com/watch?a=1&b=2&v=Z")
+        );
+        assert_eq!(
+            normalize_http_identity_url("https://youtube.com/watch?b=2&a=1&v=Z").as_deref(),
+            Some("https://www.youtube.com/watch?a=1&b=2&v=Z")
+        );
+    }
+
+    #[test]
+    fn youtube_embed_to_watch() {
+        assert_eq!(
+            normalize_http_identity_url("https://www.youtube.com/embed/dQw4w9WgXcQ").as_deref(),
+            Some("https://www.youtube.com/watch?v=dQw4w9WgXcQ")
+        );
+    }
+
+    #[test]
+    fn youtube_shorts_host() {
+        assert_eq!(
+            normalize_http_identity_url("https://youtube.com/shorts/AbCdEfGhIjK").as_deref(),
+            Some("https://www.youtube.com/shorts/AbCdEfGhIjK")
+        );
+    }
+
+    #[test]
+    fn arbitrary_query_sorted() {
+        assert_eq!(
+            normalize_http_identity_url("https://example.com/x?z=1&a=2").as_deref(),
+            Some("https://example.com/x?a=2&z=1")
+        );
+    }
+}


Side B — contributor: tommy-mor
Side B — 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 B — 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"
+        );
+    }
+}