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:
[2fe70b0e] themes

Side A — unified diff (full patch):
diff --git a/server/src/api/auth.rs b/server/src/api/auth.rs
index 559db65de14c6157690ffbf18eca0cf65b0a5202..b3631b06153d52f88348fef927e7a024b7b85ad6 100644
--- a/server/src/api/auth.rs
+++ b/server/src/api/auth.rs
@@ -1,7 +1,7 @@
 use axum::{
     body::Body,
     extract::{Path, Query, State},
-    http::{header, HeaderMap, HeaderValue, StatusCode},
+    http::{header, HeaderMap, HeaderValue, StatusCode, Uri},
     response::{IntoResponse, Redirect, Response},
     Form, Json,
 };
@@ -17,7 +17,7 @@ use crate::{
     events::{Event, GrantAdded, TokenIssued, UserRegistered},
     html::{
         auth_complete_page, auth_signed_in_fragment, choose_username_error_fragment,
-        choose_username_page, JsBuilder,
+        choose_username_page, theme_cookie_header_from_jar, theme_from_jar, theme_next_from_uri, JsBuilder,
     },
     identity::{parse_agent, parse_username},
     reducer::ReducerState,
@@ -48,15 +48,17 @@ fn js_form_error_fragment(session: &str, error: &str) -> Response {
         .into_response()
 }
 
-fn js_signed_in_fragment(bearer: &str) -> Response {
+fn js_signed_in_fragment(bearer: &str, jar: &CookieJar) -> Response {
     let mut response = JsBuilder::new()
         .id("choose-username-form")
         .morph_inner(auth_signed_in_fragment())
         .redirect("/auth/complete")
         .into_response();
-    response
-        .headers_mut()
-        .insert(header::SET_COOKIE, session_cookie_header_value(bearer));
+    let headers = response.headers_mut();
+    headers.append(header::SET_COOKIE, session_cookie_header_value(bearer));
+    if let Some(theme) = theme_cookie_header_from_jar(jar) {
+        headers.append(header::SET_COOKIE, theme);
+    }
     response
 }
 
@@ -69,13 +71,18 @@ pub fn optional_principal(headers: &HeaderMap, jar: &CookieJar, reduced: &Reduce
     verify_token(reduced, c.value()).ok()
 }
 
-fn redirect_with_session_cookie(public_url: &str, path_and_query: &str, bearer: &str) -> Response {
-    Response::builder()
+fn redirect_with_session_cookie(public_url: &str, path_and_query: &str, bearer: &str, jar: &CookieJar) -> Response {
+    let mut res = Response::builder()
         .status(StatusCode::TEMPORARY_REDIRECT)
         .header(header::LOCATION, format!("{public_url}{path_and_query}"))
-        .header(header::SET_COOKIE, session_cookie_header_value(bearer))
         .body(Body::empty())
-        .unwrap()
+        .unwrap();
+    let headers = res.headers_mut();
+    headers.append(header::SET_COOKIE, session_cookie_header_value(bearer));
+    if let Some(theme) = theme_cookie_header_from_jar(jar) {
+        headers.append(header::SET_COOKIE, theme);
+    }
+    res
 }
 
 async fn apply_invite_redemption(state: &AppState, invite_token: &str, grantee_username: &str) -> Result<(), String> {
@@ -286,7 +293,11 @@ pub struct AuthCallbackQuery {
     pub state: String,
 }
 
-pub async fn get_auth_callback(Query(q): Query<AuthCallbackQuery>, State(state): State<AppState>) -> impl IntoResponse {
+pub async fn get_auth_callback(
+    Query(q): Query<AuthCallbackQuery>,
+    State(state): State<AppState>,
+    jar: CookieJar,
+) -> impl IntoResponse {
     let sessions = pending_sessions(&state);
     {
         let sessions_read = sessions.read().await;
@@ -365,7 +376,7 @@ pub async fn get_auth_callback(Query(q): Query<AuthCallbackQuery>, State(state):
             }
             let cookie_bearer = bearer.clone();
             s.complete = Some((username, bearer));
-            return redirect_with_session_cookie(&public_url, "/", &cookie_bearer).into_response();
+            return redirect_with_session_cookie(&public_url, "/", &cookie_bearer, &jar).into_response();
         }
     }
 
@@ -378,14 +389,20 @@ pub struct ChooseUsernameQuery {
     pub error: Option<String>,
 }
 
-pub async fn get_choose_username(Query(q): Query<ChooseUsernameQuery>, State(state): State<AppState>) -> impl IntoResponse {
+pub async fn get_choose_username(
+    Query(q): Query<ChooseUsernameQuery>,
+    State(state): State<AppState>,
+    jar: CookieJar,
+    uri: Uri,
+) -> impl IntoResponse {
     let sessions = pending_sessions(&state);
     let sessions_read = sessions.read().await;
     if !sessions_read.contains_key(&q.session) {
         return api_error(StatusCode::NOT_FOUND, "unknown session", None).into_response();
     }
     drop(sessions_read);
-    choose_username_page(&q.session, q.error.as_deref()).into_response()
+    let next = theme_next_from_uri(&uri);
+    choose_username_page(&q.session, q.error.as_deref(), theme_from_jar(&jar), &next).into_response()
 }
 
 #[derive(Debug, Deserialize)]
@@ -396,6 +413,7 @@ pub struct ChooseUsernameForm {
 
 pub async fn post_choose_username(
     State(state): State<AppState>,
+    jar: CookieJar,
     Form(form): Form<ChooseUsernameForm>,
 ) -> impl IntoResponse {
     let canon_user = match parse_username(&form.username) {
@@ -477,7 +495,7 @@ pub async fn post_choose_username(
         s.complete = Some((canon_user.clone(), bearer.clone()));
     }
 
-    js_signed_in_fragment(&bearer).into_response()
+    js_signed_in_fragment(&bearer, &jar).into_response()
 }
 
 /// Start a browser-only OAuth flow (no CLI polling). Sets session cookie on success.
@@ -569,8 +587,9 @@ pub async fn get_pending_session(
     .into_response()
 }
 
-pub async fn get_auth_complete() -> impl IntoResponse {
-    auth_complete_page()
+pub async fn get_auth_complete(jar: CookieJar, uri: Uri) -> impl IntoResponse {
+    let next = theme_next_from_uri(&uri);
+    auth_complete_page(theme_from_jar(&jar), &next).into_response()
 }
 
 pub async fn get_whoami(State(state): State<AppState>, headers: HeaderMap) -> impl IntoResponse {
diff --git a/server/src/api/helpers.rs b/server/src/api/helpers.rs
index 81e2a55fa3abb8609b4099f91a989480336e11eb..9b71491e9f9efc44a2a4beba09be8f64bd2ff2ee 100644
--- a/server/src/api/helpers.rs
+++ b/server/src/api/helpers.rs
@@ -39,6 +39,55 @@ pub fn item_path_for_api(item: &str) -> String {
     }
 }
 
+/// 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);
@@ -188,3 +237,52 @@ 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/rpc.rs b/server/src/api/rpc.rs
index 31f5fcfb4eaf4df0a9cbac532dd3dedfe3611810..5b91f5836625eedbb1cd9423168046e3fb576c17 100644
--- a/server/src/api/rpc.rs
+++ b/server/src/api/rpc.rs
@@ -27,8 +27,9 @@ use crate::{
 
 use super::auth::verify_bearer_principal;
 use super::helpers::{
-    compute_connectivity_stats, is_pair_voted, item_path_for_api, now_ms, paginate_rankings,
-    parse_parent_specs, pick_random_distinct, resolve_item, vote_touches_path,
+    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,
 };
 use super::validate::{normalize_room_and_thread, validate_ingest_document};
 
@@ -148,6 +149,7 @@ fn compute_scope_rank_changes(
     parent: &str,
     before: &crate::scope_rank::ChildrenRankings,
     after: &crate::scope_rank::ChildrenRankings,
+    room_wire: &str,
 ) -> Option<ScopeRankChanges> {
     fn build_positions(rankings: &crate::scope_rank::ChildrenRankings) -> HashMap<String, Option<RankPosition>> {
         let mut map = HashMap::new();
@@ -182,7 +184,7 @@ fn compute_scope_rank_changes(
         };
         if changed {
             changes.push(RankChange {
-                item: item_path_for_api(&item),
+                item: item_path_for_api_in_room(&item, room_wire),
                 before: b,
                 after: a,
             });
@@ -204,7 +206,7 @@ fn compute_scope_rank_changes(
         parent: if parent.is_empty() {
             "/".to_string()
         } else {
-            item_path_for_api(parent)
+            item_path_for_api_in_room(parent, room_wire)
         },
         changes,
     })
@@ -256,6 +258,7 @@ fn build_rank_response_for_content(
     offset: usize,
     limit: Option<usize>,
     want_percent: bool,
+    room_wire: &str,
 ) -> Result<RankResponse, RpcErr> {
     let parent_owned = parent.map(|s| s.to_string());
     let specs = parse_parent_specs(parent_owned.as_ref());
@@ -299,7 +302,7 @@ fn build_rank_response_for_content(
                     .ranked
                     .into_iter()
                     .map(|r| RankRow {
-                        item: item_path_for_api(r.item.as_str()),
+                        item: item_path_for_api_in_room(r.item.as_str(), room_wire),
                         percent: if want_percent {
                             Some((r.score / max_score) * 100.0)
                         } else {
@@ -315,7 +318,7 @@ fn build_rank_response_for_content(
     let prefixed_unranked: Vec<String> = rankings
         .unranked_items
         .into_iter()
-        .map(|s| item_path_for_api(s.as_str()))
+        .map(|s| item_path_for_api_in_room(s.as_str(), room_wire))
         .collect();
 
     let (components, unranked_items) = if offset > 0 || limit.is_some() {
@@ -522,7 +525,7 @@ async fn rpc_post(
             .filter_map(|p| {
                 let before = pre_rankings.get(p)?;
                 let after = crate::scope_rank::build_children_rankings(content, p);
-                compute_scope_rank_changes(p.as_str(), before, &after)
+                compute_scope_rank_changes(p.as_str(), before, &after, &room_key)
             })
             .collect();
         if v.is_empty() { None } else { Some(v) }
@@ -530,14 +533,28 @@ async fn rpc_post(
         None
     };
 
+    let (pair_hint, rank_hint, web_url) = if room_key == "public" {
+        (
+            "npx slugsocial public garden pair".to_string(),
+            "npx slugsocial public garden rank".to_string(),
+            forum_thread_web_url("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),
+        )
+    };
+
     Ok(RpcResult::PostOk {
         events_appended,
         ranking_changes,
         threads: vec![format!("#{}", thread_id)],
         next: NextMoves {
-            pair: "npx slugsocial public garden pair".to_string(),
-            rank: "npx slugsocial public garden rank".to_string(),
-            web: format!("https://slug.social/t/{}", thread_id),
+            pair: pair_hint,
+            rank: rank_hint,
+            web: web_url,
         },
     })
 }
@@ -609,7 +626,7 @@ async fn rpc_check(
         raw: v.raw_text.clone(),
         principal,
         delegate,
-        room_id: room_key,
+        room_id: room_key.clone(),
         thread_tag: thread_id.clone(),
     });
 
@@ -647,7 +664,7 @@ async fn rpc_check(
                         .ranked
                         .into_iter()
                         .map(|r| RankRow {
-                            item: item_path_for_api(r.item.as_str()),
+                            item: item_path_for_api_in_room(r.item.as_str(), &room_key),
                             score: r.score,
                             percent: None,
                         })
@@ -655,25 +672,35 @@ async fn rpc_check(
                 })
                 .collect();
             CheckScopeRanking {
-                parent: item_path_for_api(parent.as_str()),
+                parent: item_path_for_api_in_room(parent.as_str(), &room_key),
                 components,
                 unranked_items: scoped
                     .unranked_items
                     .into_iter()
-                    .map(|it| item_path_for_api(it.as_str()))
+                    .map(|it| item_path_for_api_in_room(it.as_str(), &room_key))
                     .collect(),
             }
         })
         .collect();
 
+    let check_next = if room_key == "public" {
+        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),
+        ]
+    } 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),
+        ]
+    };
+
     Ok(RpcResult::CheckOk {
         rankings,
         threads: vec![format!("#{}", thread_id)],
-        next: vec![
-            "npx slugsocial public forum post <TAG> --delegate <uuid:rig:model>".to_string(),
-            "npx slugsocial public forum list".to_string(),
-            format!("https://slug.social/t/{}", thread_id),
-        ],
+        next: check_next,
     })
 }
 
@@ -690,7 +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: format!("https://slug.social/t/{}", tag),
+            web: forum_thread_web_url(room, tag),
         })
         .collect();
     out.sort_by(|a, b| b.last_activity_ts.cmp(&a.last_activity_ts));
@@ -1031,8 +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(&left),
-        right: item_path_for_api(&right),
+        left: item_path_for_api_in_room(&left, &room),
+        right: item_path_for_api_in_room(&right, &room),
         left_body: lb,
         right_body: rb,
         threads: th,
@@ -1088,6 +1115,7 @@ pub async fn handle_rpc_batch(
                     offset.unwrap_or(0),
                     limit,
                     percent.unwrap_or(false),
+                    &room,
                 ) {
                     Ok(r) => line_ok(RpcResult::GardenRank(r)),
                     Err((e, h)) => line_err(e, h),
@@ -1109,7 +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(&item_str))),
+                        Some(format!("{} does not exist", item_path_for_api_in_room(&item_str, &room))),
                     )
                 } else {
                     const MAX_ITEM_BODY: usize = 10_000;
@@ -1132,7 +1160,7 @@ pub async fn handle_rpc_batch(
                         .map(|s| s.iter().cloned().collect())
                         .unwrap_or_default();
                     line_ok(RpcResult::GardenItem(ItemResponse {
-                        item: item_str,
+                        item: item_path_for_api_in_room(&item_str, &room),
                         body,
                         truncated,
                         body_len,
@@ -1525,7 +1553,11 @@ pub async fn handle_rpc_batch(
                     let range = (top - bot).max(1e-12);
                     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(r.item.as_str()), score: r.score, percent: pct });
+                        ranked.push(RankRow {
+                            item: item_path_for_api_in_room(r.item.as_str(), &room),
+                            score: r.score,
+                            percent: pct,
+                        });
                     }
                 }
 
@@ -1542,7 +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(&it),
+                        item: item_path_for_api_in_room(&it, &room),
                         score: 0.0,
                         percent: want_percent.then_some(0.0),
                     }))
@@ -1586,7 +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(&item_str))),
+                        Some(format!("{} does not exist", item_path_for_api_in_room(&item_str, &room))),
                     )
                 } else {
                     let votes: Vec<VoteRow> = content
@@ -1597,8 +1629,8 @@ pub async fn handle_rpc_batch(
                                 .take(limit)
                                 .map(|v| VoteRow {
                                     ts: v.ts,
-                                    a: v.a.as_str().to_string(),
-                                    b: v.b.as_str().to_string(),
+                                    a: item_path_for_api_in_room(v.a.as_str(), &room),
+                                    b: item_path_for_api_in_room(v.b.as_str(), &room),
                                     ratio: format!("{}:{}", v.ratio_left, v.ratio_right),
                                     actor: Some(v.principal.clone()),
                                     body: v.body.clone(),
@@ -1608,7 +1640,7 @@ pub async fn handle_rpc_batch(
                         })
                         .unwrap_or_default();
                     line_ok(RpcResult::Matchup(MatchupResponse {
-                        item: item_path_for_api(&item_str),
+                        item: item_path_for_api_in_room(&item_str, &room),
                         votes,
                     }))
                 }
@@ -1635,8 +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(&a),
-                                            b: item_path_for_api(&b),
+                                            a: item_path_for_api_in_room(&a, &room),
+                                            b: item_path_for_api_in_room(&b, &room),
                                             ratio: format!("{}:{}", ratio_left, ratio_right),
                                             actor: reduced.ingests_by_id.get(&e.post_id).map(|ing| ing.principal.clone()),
                                             body: explanation,
@@ -1672,7 +1704,7 @@ pub async fn handle_rpc_batch(
                     }
                 }).collect();
                 line_ok(RpcResult::RankHistory(RankHistoryResponse {
-                    item: item_path_for_api(&item_str),
+                    item: item_path_for_api_in_room(&item_str, &room),
                     history,
                 }))
                 }
@@ -1691,6 +1723,10 @@ pub async fn handle_rpc_batch(
                     .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))
+                    .collect();
                 line_ok(RpcResult::Leaves(LeavesResponse { paths }))
                 }
             },
@@ -1707,10 +1743,21 @@ 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: format!("~/{}", path),
+                                    path: path_label,
                                     children,
-                                    web: format!("https://slug.social/~/{}", path),
+                                    web: item_path_for_api_in_room(path.as_str(), &room),
                                 }
                             }).collect();
                         v.sort_by(|a, b| a.path.cmp(&b.path));
@@ -1743,8 +1790,8 @@ pub async fn handle_rpc_batch(
                     .take(limit)
                     .map(|v| VoteRow {
                         ts: v.ts,
-                        a: v.a.as_str().to_string(),
-                        b: v.b.as_str().to_string(),
+                        a: item_path_for_api_in_room(v.a.as_str(), &room),
+                        b: item_path_for_api_in_room(v.b.as_str(), &room),
                         ratio: format!("{}:{}", v.ratio_left, v.ratio_right),
                         actor: Some(v.principal.clone()),
                         body: v.body.clone(),
diff --git a/server/src/html/auth.rs b/server/src/html/auth.rs
index d57b1c725ce3e06b1d904882b9388c3da48d85cb..5df77c76b89ed2bb11d936e1dbb804d50a0e79a1 100644
--- a/server/src/html/auth.rs
+++ b/server/src/html/auth.rs
@@ -23,7 +23,7 @@ fn form_inner(session: &str, error: Option<&str>) -> Markup {
     }
 }
 
-pub fn choose_username_page(session: &str, error: Option<&str>) -> Markup {
+pub fn choose_username_page(session: &str, error: Option<&str>, theme: &str, theme_next: &str) -> Markup {
     let body = html! {
         nav.breadcrumb {
             a href="/" { "slug.social" }
@@ -36,7 +36,7 @@ pub fn choose_username_page(session: &str, error: Option<&str>) -> Markup {
             (form_inner(session, error))
         }
     };
-    super::layout("join — slug.social", "view-auth", body, None)
+    super::layout("join — slug.social", "view-auth", body, None, theme, theme_next)
 }
 
 /// Fragment returned to the poem JS on error — replaces the form's innerHTML.
@@ -52,7 +52,7 @@ pub fn auth_signed_in_fragment() -> Markup {
     }
 }
 
-pub fn auth_complete_page() -> Markup {
+pub fn auth_complete_page(theme: &str, theme_next: &str) -> Markup {
     let body = html! {
         nav.breadcrumb {
             a href="/" { "slug.social" }
@@ -63,5 +63,5 @@ pub fn auth_complete_page() -> Markup {
         p { "Return to your terminal — your agent is polling and will collect your token automatically." }
         p.auth-hint { "You can close this tab." }
     };
-    super::layout("signed in — slug.social", "view-auth", body, None)
+    super::layout("signed in — slug.social", "view-auth", body, None, theme, theme_next)
 }
diff --git a/server/src/html/editor.rs b/server/src/html/editor.rs
index 07f6ab3b778f07f60765fa3f39060ebc5f72bc1a..ecdd226b1b17d5f11d1b79f99add5759ef918281 100644
--- a/server/src/html/editor.rs
+++ b/server/src/html/editor.rs
@@ -1,8 +1,10 @@
 use axum::{
     extract::State,
+    http::Uri,
     response::{Html, IntoResponse},
     Form,
 };
+use axum_extra::extract::cookie::CookieJar;
 use maud::{html, Markup};
 use serde::Deserialize;
 
@@ -13,7 +15,7 @@ use crate::{
     state::AppState,
 };
 
-use super::{bc_segment, layout};
+use super::{bc_segment, layout, theme_from_jar, theme_next_from_uri};
 
 fn bc_try() -> Markup {
     html! {
@@ -23,7 +25,7 @@ fn bc_try() -> Markup {
 }
 
 /// The interactive editor page — `/try`.
-pub async fn editor_page() -> impl IntoResponse {
+pub async fn editor_page(jar: CookieJar, uri: Uri) -> impl IntoResponse {
     let page = layout(
         "try — slug.social",
         "view-thread",
@@ -68,6 +70,8 @@ pub async fn editor_page() -> impl IntoResponse {
 "#)) }
         },
         None,
+        theme_from_jar(&jar),
+        &theme_next_from_uri(&uri),
     );
     Html(page.into_string())
 }
diff --git a/server/src/html/forum.rs b/server/src/html/forum.rs
index 5c5f9e2ba0e5cb1d661c113117988ec80c01deca..368b1016eb43d83e9ff39464ff6164fa9a8b558a 100644
--- a/server/src/html/forum.rs
+++ b/server/src/html/forum.rs
@@ -1,6 +1,6 @@
 use axum::{
     extract::{Path, Query, State},
-    http::{HeaderMap, StatusCode},
+    http::{HeaderMap, StatusCode, Uri},
     response::{Html, IntoResponse},
 };
 use axum_extra::extract::cookie::CookieJar;
@@ -19,7 +19,7 @@ use crate::{
 
 use super::{
     bc_segment, bc_threads, cli_panel, layout, now_ms, profile_href, recency_class,
-    render_linkified_with_embeds_in_scope, JsBuilder,
+    render_linkified_with_embeds_in_scope, theme_from_jar, theme_next_from_uri, JsBuilder,
 };
 
 #[derive(Clone)]
@@ -577,6 +577,7 @@ pub async fn home(
     State(state): State<AppState>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let now = now_ms();
     let reduced = state.reduced.read().await;
@@ -624,6 +625,8 @@ pub async fn home(
             (cli_panel("npx slugsocial public forum list"))
         },
         None,
+        theme_from_jar(&jar),
+        &theme_next_from_uri(&uri),
     );
     Html(page.into_string())
 }
@@ -679,6 +682,7 @@ async fn thread_view_inner(
     nav: ThreadNav,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let tag = canonicalize_tag(&tag);
     let scope = nav.scope();
@@ -778,6 +782,8 @@ async fn thread_view_inner(
             (cli_panel(&cli))
         },
         None,
+        theme_from_jar(&jar),
+        &theme_next_from_uri(&uri),
     );
     Html(page.into_string()).into_response()
 }
@@ -789,8 +795,9 @@ pub async fn thread_view(
     Query(q): Query<ThreadViewQuery>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
-    thread_view_inner(state, tag, q, ThreadNav::public(), headers, jar).await
+    thread_view_inner(state, tag, q, ThreadNav::public(), headers, jar, uri).await
 }
 
 /// Room thread — `/r/:short/:slug/t/:tag`
@@ -800,31 +807,39 @@ pub async fn room_thread_view(
     Query(q): Query<ThreadViewQuery>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let room_id = format!("{room_short}/{room_slug}");
     let reduced = state.reduced.read().await;
     let user = optional_principal(&headers, &jar, &reduced);
     if !user_can_view_room(&reduced, &room_id, user.as_deref()) {
         drop(reduced);
-        return room_not_found_page().into_response();
+        return room_not_found_page(&jar, &uri).into_response();
     }
     drop(reduced);
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         return (StatusCode::NOT_FOUND, "bad room path").into_response();
     };
-    thread_view_inner(state, tag, q, nav, headers, jar)
+    thread_view_inner(state, tag, q, nav, headers, jar, uri)
         .await
         .into_response()
 }
 
-fn room_not_found_page() -> impl IntoResponse {
+fn room_not_found_page(jar: &CookieJar, uri: &Uri) -> impl IntoResponse {
     let body = html! {
         nav class="breadcrumb" { a href="/" { "slug.social" } }
         h1 { "not found" }
         p { "The requested page could not be found." }
         p { a href="/" { "home" } }
     };
-    let page = layout("not found — slug.social", "view-thread", body, None);
+    let page = layout(
+        "not found — slug.social",
+        "view-thread",
+        body,
+        None,
+        theme_from_jar(jar),
+        &theme_next_from_uri(uri),
+    );
     (StatusCode::NOT_FOUND, Html(page.into_string()))
 }
 
@@ -834,6 +849,7 @@ pub async fn room_page(
     Path((room_short, room_slug)): Path<(String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let room_id = format!("{room_short}/{room_slug}");
     let now = now_ms();
@@ -845,7 +861,7 @@ pub async fn room_page(
     let user = optional_principal(&headers, &jar, &reduced);
     if !user_can_view_room(&reduced, &room_id, user.as_deref()) {
         drop(reduced);
-        return room_not_found_page().into_response();
+        return room_not_found_page(&jar, &uri).into_response();
     }
     let scope = ScopeId::Room(room_id.clone());
     let mut rows = collect_thread_rows_for_scope(&reduced, &scope, now);
@@ -902,6 +918,8 @@ pub async fn room_page(
             (cli_panel(&audit_cli))
         },
         None,
+        theme_from_jar(&jar),
+        &theme_next_from_uri(&uri),
     );
     Html(page.into_string()).into_response()
 }
@@ -943,6 +961,8 @@ async fn thread_post_view_inner(
     index_str: String,
     nav: ThreadNav,
     viewer: Option<String>,
+    jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let tag = canonicalize_tag(&tag);
     let index: usize = index_str.parse().unwrap_or(0);
@@ -987,6 +1007,8 @@ async fn thread_post_view_inner(
             }
         },
         None,
+        theme_from_jar(&jar),
+        &theme_next_from_uri(&uri),
     );
     Html(page.into_string()).into_response()
 }
@@ -996,11 +1018,12 @@ pub async fn thread_post_view(
     Path((tag, index_str)): Path<(String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let reduced = state.reduced.read().await;
     let viewer = optional_principal(&headers, &jar, &reduced);
     drop(reduced);
-    thread_post_view_inner(state, tag, index_str, ThreadNav::public(), viewer)
+    thread_post_view_inner(state, tag, index_str, ThreadNav::public(), viewer, jar, uri)
         .await
 }
 
@@ -1009,19 +1032,20 @@ pub async fn room_thread_post_view(
     Path((room_short, room_slug, tag, index_str)): Path<(String, String, String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let room_id = format!("{room_short}/{room_slug}");
     let reduced = state.reduced.read().await;
     let user = optional_principal(&headers, &jar, &reduced);
     if !user_can_view_room(&reduced, &room_id, user.as_deref()) {
         drop(reduced);
-        return room_not_found_page().into_response();
+        return room_not_found_page(&jar, &uri).into_response();
     }
     drop(reduced);
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         return (StatusCode::NOT_FOUND, "bad room path").into_response();
     };
-    thread_post_view_inner(state, tag, index_str, nav, user)
+    thread_post_view_inner(state, tag, index_str, nav, user, jar, uri)
         .await
         .into_response()
 }
@@ -1193,6 +1217,7 @@ pub async fn user_profile_page(
     Path(username): Path<String>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let canon = match parse_username(&username) {
         Ok(u) => u,
@@ -1270,6 +1295,8 @@ pub async fn user_profile_page(
             (cli_panel(&format!("npx slugsocial public forum list")))
         },
         None,
+        theme_from_jar(&jar),
+        &theme_next_from_uri(&uri),
     );
     Html(page.into_string()).into_response()
 }
@@ -1292,13 +1319,14 @@ pub async fn room_thread_post_expand(
     Path((room_short, room_slug, tag, index_str)): Path<(String, String, String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let room_id = format!("{room_short}/{room_slug}");
     let reduced = state.reduced.read().await;
     let user = optional_principal(&headers, &jar, &reduced);
     if !user_can_view_room(&reduced, &room_id, user.as_deref()) {
         drop(reduced);
-        return room_not_found_page().into_response();
+        return room_not_found_page(&jar, &uri).into_response();
     }
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         drop(reduced);
@@ -1328,13 +1356,14 @@ pub async fn room_thread_post_expand_deleted(
     Path((room_short, room_slug, tag, index_str)): Path<(String, String, String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let room_id = format!("{room_short}/{room_slug}");
     let reduced = state.reduced.read().await;
     let user = optional_principal(&headers, &jar, &reduced);
     if !user_can_view_room(&reduced, &room_id, user.as_deref()) {
         drop(reduced);
-        return room_not_found_page().into_response();
+        return room_not_found_page(&jar, &uri).into_response();
     }
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         drop(reduced);
@@ -1364,13 +1393,14 @@ pub async fn room_thread_post_collapse_deleted(
     Path((room_short, room_slug, tag, index_str)): Path<(String, String, String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let room_id = format!("{room_short}/{room_slug}");
     let reduced = state.reduced.read().await;
     let user = optional_principal(&headers, &jar, &reduced);
     if !user_can_view_room(&reduced, &room_id, user.as_deref()) {
         drop(reduced);
-        return room_not_found_page().into_response();
+        return room_not_found_page(&jar, &uri).into_response();
     }
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         drop(reduced);
diff --git a/server/src/html/garden.rs b/server/src/html/garden.rs
index e08f068ae04f5a2542ec2c43c240f931f87146bf..9b4789a79c3e293cbfc5f033a0eac8650320d94d 100644
--- a/server/src/html/garden.rs
+++ b/server/src/html/garden.rs
@@ -1,6 +1,6 @@
 use axum::{
     extract::{Path, State},
-    http::{HeaderMap, StatusCode},
+    http::{HeaderMap, StatusCode, Uri},
     response::{Html, IntoResponse},
 };
 use axum_extra::extract::cookie::CookieJar;
@@ -20,7 +20,8 @@ use crate::{
 
 use super::{
     bc_path, bc_segment, cli_panel, layout, now_ms, ratio_pct,
-    render_linkified_with_embeds_in_scope, breadcrumb_path::OntologyPath,
+    render_linkified_with_embeds_in_scope, theme_from_jar, theme_next_from_uri,
+    breadcrumb_path::OntologyPath,
     forum::ThreadNav,
 };
 
@@ -59,14 +60,21 @@ fn scoped_bc_path(path: &OntologyPath, nav: &ThreadNav) -> maud::Markup {
     }
 }
 
-fn room_not_found_page() -> impl IntoResponse {
+fn room_not_found_page(jar: &CookieJar, uri: &Uri) -> impl IntoResponse {
     let body = html! {
         nav class="breadcrumb" { a href="/" { "slug.social" } }
         h1 { "not found" }
         p { "The requested page could not be found." }
         p { a href="/" { "home" } }
     };
-    let page = layout("not found — slug.social", "view-thread", body, None);
+    let page = layout(
+        "not found — slug.social",
+        "view-thread",
+        body,
+        None,
+        theme_from_jar(jar),
+        &theme_next_from_uri(uri),
+    );
     (StatusCode::NOT_FOUND, Html(page.into_string()))
 }
 
@@ -81,7 +89,11 @@ fn user_can_view_room(reduced: &ReducerState, room_id: &str, username: Option<&s
 }
 
 /// Ontology index — root-level paths. Private (UUID) roots are excluded.
-pub async fn garden_index(State(state): State<AppState>) -> impl IntoResponse {
+pub async fn garden_index(
+    State(state): State<AppState>,
+    jar: CookieJar,
+    uri: Uri,
+) -> impl IntoResponse {
     let nav = ThreadNav::public();
     let child_rankings = {
         let reduced = state.reduced.read().await;
@@ -130,6 +142,8 @@ pub async fn garden_index(State(state): State<AppState>) -> impl IntoResponse {
             (cli_panel("npx slugsocial garden tree"))
         },
         None,
+        theme_from_jar(&jar),
+        &theme_next_from_uri(&uri),
     );
     Html(page.into_string())
 }
@@ -138,9 +152,11 @@ pub async fn garden_index(State(state): State<AppState>) -> impl IntoResponse {
 pub async fn ontology_path(
     State(state): State<AppState>,
     Path(path): Path<String>,
+    jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let path = OntologyPath::from_input(&path);
-    render_scope_view(state, path, ThreadNav::public()).await
+    render_scope_view(state, path, ThreadNav::public(), jar, uri).await
 }
 
 pub async fn room_garden_index(
@@ -148,19 +164,20 @@ pub async fn room_garden_index(
     Path((room_short, room_slug)): Path<(String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let room_id = format!("{room_short}/{room_slug}");
     let reduced = state.reduced.read().await;
     let user = optional_principal(&headers, &jar, &reduced);
     if !user_can_view_room(&reduced, &room_id, user.as_deref()) {
         drop(reduced);
-        return room_not_found_page().into_response();
+        return room_not_found_page(&jar, &uri).into_response();
     }
     drop(reduced);
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         return (StatusCode::NOT_FOUND, "bad room path").into_response();
     };
-    render_scope_view(state, OntologyPath::root(), nav).await
+    render_scope_view(state, OntologyPath::root(), nav, jar, uri).await
 }
 
 pub async fn room_ontology_path(
@@ -168,20 +185,21 @@ pub async fn room_ontology_path(
     Path((room_short, room_slug, path)): Path<(String, String, String)>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let room_id = format!("{room_short}/{room_slug}");
     let reduced = state.reduced.read().await;
     let user = optional_principal(&headers, &jar, &reduced);
     if !user_can_view_room(&reduced, &room_id, user.as_deref()) {
         drop(reduced);
-        return room_not_found_page().into_response();
+        return room_not_found_page(&jar, &uri).into_response();
     }
     drop(reduced);
     let Some(nav) = ThreadNav::from_room_id(&room_id) else {
         return (StatusCode::NOT_FOUND, "bad room path").into_response();
     };
     let path = OntologyPath::from_input(&path);
-    render_scope_view(state, path, nav).await
+    render_scope_view(state, path, nav, jar, uri).await
 }
 
 #[derive(Debug, Clone)]
@@ -375,6 +393,8 @@ async fn render_scope_view(
     state: AppState,
     path: OntologyPath,
     nav: ThreadNav,
+    jar: CookieJar,
+    uri: Uri,
 ) -> axum::response::Response {
     let scope = nav.scope();
     let model = {
@@ -525,6 +545,8 @@ async fn render_scope_view(
             (cli_panel(&cli))
         },
         None,
+        theme_from_jar(&jar),
+        &theme_next_from_uri(&uri),
     );
 
     Html(page.into_string()).into_response()
diff --git a/server/src/html/mod.rs b/server/src/html/mod.rs
index a8fd73433d120b07351dd027faf0b25f8f101321..53041a0cf0b30e6f20749c92ecc15a4e9ac56e09 100644
--- a/server/src/html/mod.rs
+++ b/server/src/html/mod.rs
@@ -1,10 +1,13 @@
 use axum::{
     body::Body,
     extract::Path,
-    http::{header, StatusCode},
+    http::{header, HeaderValue, StatusCode, Uri},
     response::{IntoResponse, Response},
+    Form,
 };
+use axum_extra::extract::cookie::CookieJar;
 use maud::{html, Markup, DOCTYPE};
+use serde::Deserialize;
 use std::collections::HashSet;
 
 mod auth;
@@ -33,6 +36,75 @@ pub(crate) fn profile_href(username: &str) -> String {
     format!("/u/{username}")
 }
 
+/// Cookie name for UI theme (must match document.cookie migration in [`layout`]).
+pub const SLUG_THEME_COOKIE: &str = "slug-theme";
+
+/// Normalize a requested theme id to a known stylesheet key.
+pub fn normalize_theme(raw: &str) -> &'static str {
+    match raw {
+        "retro" => "retro",
+        "retro_craft" => "retro_craft",
+        _ => "default",
+    }
+}
+
+/// Resolved theme for rendering and cookie re-issue.
+pub fn theme_from_jar(jar: &CookieJar) -> &'static str {
+    jar.get(SLUG_THEME_COOKIE)
+        .map(|c| normalize_theme(c.value()))
+        .unwrap_or("default")
+}
+
+/// `Path` + optional `?query` for round-tripping after `POST /theme`.
+pub fn theme_next_from_uri(uri: &Uri) -> String {
+    uri.path_and_query()
+        .map(|pq| pq.as_str().to_string())
+        .filter(|s| !s.is_empty())
+        .unwrap_or_else(|| "/".to_string())
+}
+
+/// `Set-Cookie` for a validated theme (ASCII cookie value).
+pub fn theme_cookie_header_value(theme: &str) -> HeaderValue {
+    let t = normalize_theme(theme);
+    let s = format!("{SLUG_THEME_COOKIE}={t}; Path=/; SameSite=Lax; Max-Age=31536000");
+    HeaderValue::from_str(&s).expect("theme cookie must be ASCII")
+}
+
+/// Re-issue theme cookie on responses that also set `slug_session`, so login does not drop theme.
+pub fn theme_cookie_header_from_jar(jar: &CookieJar) -> Option<HeaderValue> {
+    let c = jar.get(SLUG_THEME_COOKIE)?;
+    Some(theme_cookie_header_value(c.value()))
+}
+
+fn sanitize_theme_next(next: Option<&str>) -> String {
+    let s = next.unwrap_or("/").trim();
+    if s.starts_with('/') && !s.starts_with("//") && s.len() < 8192 {
+        s.to_string()
+    } else {
+        "/".to_string()
+    }
+}
+
+#[derive(Debug, Deserialize)]
+pub struct ThemeForm {
+    theme: String,
+    next: Option<String>,
+}
+
+/// `POST /theme` — set theme cookie and redirect back (full navigation, no fetch).
+pub async fn post_theme(Form(form): Form<ThemeForm>) -> impl IntoResponse {
+    let theme = normalize_theme(&form.theme);
+    let next = sanitize_theme_next(form.next.as_deref());
+    let loc = HeaderValue::try_from(next.as_str())
+        .unwrap_or_else(|_| HeaderValue::from_static("/"));
+    Response::builder()
+        .status(StatusCode::SEE_OTHER)
+        .header(header::LOCATION, loc)
+        .header(header::SET_COOKIE, theme_cookie_header_value(theme))
+        .body(Body::empty())
+        .expect("theme redirect response")
+}
+
 // Embed CSS files at compile time
 const THEME_DEFAULT_CSS: &str = include_str!("../../static/theme_default.css");
 const THEME_RETRO_CSS: &str = include_str!("../../static/theme_retro.css");
@@ -173,7 +245,9 @@ impl JsQueryBuilder {
     }
 }
 
-pub(super) fn layout(title: &str, view: &str, body: Markup, views: Option<u64>) -> Markup {
+pub(super) fn layout(title: &str, view: &str, body: Markup, views: Option<u64>, theme: &str, theme_next: &str) -> Markup {
+    let theme = normalize_theme(theme);
+    let css_href = format!("/static/theme_{theme}.css");
     html! {
         (DOCTYPE)
         html {
@@ -181,7 +255,20 @@ pub(super) fn layout(title: &str, view: &str, body: Markup, views: Option<u64>)
                 meta charset="utf-8";
                 meta name="viewport" content="width=device-width, initial-scale=1";
                 title { (title) }
-                link rel="stylesheet" href="/static/theme_default.css" id="theme-stylesheet";
+                script { (maud::PreEscaped(r#"
+(function() {
+  try {
+    var ls = localStorage.getItem('slug-theme');
+    if (!ls) return;
+    var m = document.cookie.match(/(?:^|;\s*)slug-theme=([^;]+)/);
+    var c = m ? decodeURIComponent(m[1].replace(/\+/g, ' ')) : '';
+    if (ls === c) { localStorage.removeItem('slug-theme'); return; }
+    document.cookie = 'slug-theme=' + encodeURIComponent(ls) + '; Path=/; SameSite=Lax; Max-Age=31536000';
+    location.reload();
+  } catch (e) {}
+})();
+"#)) }
+                link rel="stylesheet" href=(css_href) id="theme-stylesheet";
                 script src="https://unpkg.com/idiomorph@0.3.0/dist/idiomorph.min.js" {}
             }
             body class=(view) {
@@ -196,32 +283,21 @@ pub(super) fn layout(title: &str, view: &str, body: Markup, views: Option<u64>)
                         input type="range" id="spread-slider" min="0" max="1" step="0.05" value="1";
                     }
                     a id="search-btn" href="/search" { "search" }
-                    div id="theme-switcher" { "theme" }
+                    form id="slug-theme-form" method="post" action="/theme" {
+                        input type="hidden" name="next" value=(theme_next);
+                        select id="theme-select" name="theme" onchange="this.form.submit()" aria-label="Theme" {
+                            @for (val, label) in [("default", "default"), ("retro", "retro"), ("retro_craft", "craft")] {
+                                @if theme == val {
+                                    option value=(val) selected { (label) }
+                                } @else {
+                                    option value=(val) { (label) }
+                                }
+                            }
+                        }
+                    }
                 }
 script { (maud::PreEscaped(r#"
                     (function() {
-                        // Theme switching
-                        const themes = ['default', 'retro', 'retro_craft'];
-                        const themeLabel = { default: 'default', retro: 'retro', retro_craft: 'craft' };
-                        const storedTheme = localStorage.getItem('slug-theme') || 'default';
-                        const switcher = document.getElementById('theme-switcher');
-                        const stylesheet = document.getElementById('theme-stylesheet');
-
-                        function setTheme(name) {
-                            stylesheet.href = `/static/theme_${name}.css`;
-                            localStorage.setItem('slug-theme', name);
-                            switcher.textContent = themeLabel[name] || name;
-                            setTimeout(() => setSpread(parseFloat(slider.value)), 50);
-                        }
-
-                        setTheme(storedTheme);
-
-                        switcher.addEventListener('click', function() {
-                            const current = themes.indexOf(localStorage.getItem('slug-theme') || 'default');
-                            const next = (current + 1) % themes.length;
-                            setTheme(themes[next]);
-                        });
-
                         // Spread control
                         const slider = document.getElementById('spread-slider');
                         const storedSpread = localStorage.getItem('slug-spread');
@@ -245,6 +321,7 @@ script { (maud::PreEscaped(r#"
                             const f = e.target;
                             if (!f || f.tagName !== 'FORM') return;
                             if ((f.method || 'get').toLowerCase() !== 'post') return;
+                            if (f.id === 'slug-theme-form') return;
                             e.preventDefault();
                             const resp = await fetch(f.action, {
                                 method: 'POST',
diff --git a/server/src/html/search.rs b/server/src/html/search.rs
index 0871ddb7a87e3153e2cb6c1f827b46de2c9f0f3b..28ceaa53c3fcac6777311535e95fb771b19438f5 100644
--- a/server/src/html/search.rs
+++ b/server/src/html/search.rs
@@ -1,6 +1,6 @@
 use axum::{
     extract::{Query, State},
-    http::HeaderMap,
+    http::{HeaderMap, Uri},
     response::{Html, IntoResponse},
 };
 use axum_extra::extract::cookie::CookieJar;
@@ -15,7 +15,7 @@ use crate::{
     timeago,
 };
 
-use super::{authorship_address, bc_segment, cli_panel, layout, now_ms};
+use super::{authorship_address, bc_segment, cli_panel, layout, now_ms, theme_from_jar, theme_next_from_uri};
 
 /// Escape HTML special chars for safe injection.
 fn escape_html(s: &str) -> String {
@@ -396,6 +396,7 @@ pub async fn search_page(
     Query(params): Query<SearchQuery>,
     headers: HeaderMap,
     jar: CookieJar,
+    uri: Uri,
 ) -> impl IntoResponse {
     let query = params.q.clone().unwrap_or_default();
     let results = if query.len() >= 2 {
@@ -420,6 +421,8 @@ pub async fn search_page(
             (cli_panel("npx slugsocial search <query>"))
         },
         None,
+        theme_from_jar(&jar),
+        &theme_next_from_uri(&uri),
     );
     Html(page.into_string())
 }
diff --git a/server/src/lib.rs b/server/src/lib.rs
index 43b63293c2a62b9700948767c618cb0614ddf6d9..b9d4b79791ba8dd3a3c26ff777943a2548092de5 100644
--- a/server/src/lib.rs
+++ b/server/src/lib.rs
@@ -33,6 +33,7 @@ pub fn create_app(state: AppState) -> Router {
         .route("/post", post(api::post_web_ingest))
         .route("/post/redact", post(api::post_web_redact))
         .route("/post/check", post(api::check_web_ingest))
+        .route("/theme", post(crate::html::post_theme))
         .route("/sse", get(api::get_html_stream))
         .route("/stream", get(api::get_stream))
         .route("/search", get(crate::html::search_page))
diff --git a/server/src/path_types.rs b/server/src/path_types.rs
index 997597f6659c1ba2092bc5348e393bf7a8fa7ae0..cad58cac7da948f92d6ea2a5587d917ab21d57ea 100644
--- a/server/src/path_types.rs
+++ b/server/src/path_types.rs
@@ -8,6 +8,12 @@
 //!
 //! 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}/~/…`.
 
 use std::borrow::Borrow;
 use std::fmt;
diff --git a/server/static/theme_default.css b/server/static/theme_default.css
index 2b06b12f3e77c9ed305272fe3ab47a8ad08504df..5e6304bcc36caed8aeda913fd241fc8fb9cf6d25 100644
--- a/server/static/theme_default.css
+++ b/server/static/theme_default.css
@@ -678,7 +678,10 @@ details > summary::-webkit-details-marker { display: none; }
   gap: 6px;
 }
 #spread-slider { accent-color: var(--ui); width: 80px; }
-#theme-switcher {
+#slug-theme-form {
+  display: contents;
+}
+#theme-select {
   background: var(--g4);
   border: var(--bv) solid;
   border-color: var(--hi) var(--lo) var(--lo) var(--hi);
@@ -688,8 +691,8 @@ details > summary::-webkit-details-marker { display: none; }
   padding: 2px 10px;
   user-select: none;
 }
-#theme-switcher:hover  { color: var(--signal); }
-#theme-switcher:active {
+#theme-select:hover  { color: var(--signal); }
+#theme-select:active {
   border-color: var(--lo) var(--hi) var(--hi) var(--lo);
   transform: translate(1px, 1px);
 }
diff --git a/server/static/theme_retro_craft.css b/server/static/theme_retro_craft.css
index 508222443a3bb2f16d3034a07af53a7df37a0314..3fde7e2b77fa4e4f46418927eb0fb0e5cd195c75 100644
--- a/server/static/theme_retro_craft.css
+++ b/server/static/theme_retro_craft.css
@@ -35,7 +35,6 @@ h1, h2, h3 {
   font-weight: 600;
   letter-spacing: 0.14em;
   margin: 1.5rem 0 0.5rem;
-  text-transform: uppercase;
 }
 
 a {
@@ -354,7 +353,10 @@ div.cli-panel {
   accent-color: var(--accent);
   width: 72px;
 }
-#theme-switcher,
+#slug-theme-form {
+  display: contents;
+}
+#theme-select,
 #search-btn,
 a#src-link {
   border: 1px solid var(--line);
@@ -365,7 +367,7 @@ a#src-link {
   padding: 0.25rem 0.6rem;
   text-decoration: none;
 }
-#theme-switcher:hover,
+#theme-select:hover,
 #search-btn:hover,
 a#src-link:hover {
   border-color: var(--accent);


Side B — contributor: tommy-mor
Side B — commit message:
[52f5c51c] Add Reddit OAuth linking and make UUID the only account identity.

OAuth providers only attach to a session UUID (first link creates the
principal); linked providers stay private on the account page.

Co-authored-by: Cursor <cursoragent@cursor.com>

Side B — unified diff (full patch):
diff --git a/AGENTS.md b/AGENTS.md
index 6e0fd8ebb65d665c9c1438e3275971d62b98fd95..e9cc3173dbeb21ad0fc090ca7b407b027c7820a9 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -35,8 +35,11 @@ Environment variables (defaults in `server/src/state.rs`):
 - `SORTER2_DATA_DIR` — default `./data` (created on startup)
 - `SORTER2_EVENT_LOG` — default `{data_dir}/events.jsonl`
 - `SORTER2_BASE_URL` — public origin (also drives Secure cookies when `https://`)
-- `GITHUB_CLIENT_ID` / `GITHUB_CLIENT_SECRET` — GitHub OAuth (optional; login disabled if unset)
-- `SORTER2_ALLOW_MOCK_OAUTH=1` — allow `mock_user` on `/auth/github` (tests only)
+- `GITHUB_CLIENT_ID` / `GITHUB_CLIENT_SECRET` — GitHub OAuth linking (optional)
+- `REDDIT_CLIENT_ID` / `REDDIT_CLIENT_SECRET` (or `REDDIT_APP_*`) — Reddit API import + OAuth linking (optional)
+- `SORTER2_ALLOW_MOCK_OAUTH=1` — allow `mock_user` on `/auth/github` and `/auth/reddit` (tests only)
+
+Identity: UUID is canonical. OAuth providers only *link* to a UUID (first link creates the principal). Linked providers are private to the account owner.
 
 Health check: `GET /healthz` → `ok`.
 
diff --git a/server/src/auth/mod.rs b/server/src/auth/mod.rs
index 5906f93b13853421e96a3c37bc9d8202a47842bf..c706ae8045a811e5941f5f6c72da88f42a403a82 100644
--- a/server/src/auth/mod.rs
+++ b/server/src/auth/mod.rs
@@ -1,4 +1,8 @@
-//! GitHub OAuth login, session cookies, and vote actor resolution.
+//! OAuth linking, session cookies, and vote actor resolution.
+//!
+//! Canonical identity is a UUID. OAuth providers only *link* to that UUID
+//! (first link creates the principal; later links attach while logged in).
+//! Which providers are linked is private to the account owner.
 
 pub mod config;
 pub mod identity;
@@ -22,7 +26,9 @@ use crate::{
     form_template::template_json_compact,
     html::layout,
     state::AppState,
-    storage_schema::{oauth_link_owner, pseudonym_owner, Store, StoreFields},
+    storage_schema::{
+        linked_providers_for_uuid, oauth_link_owner, pseudonym_owner, Store, StoreFields,
+    },
     ui_action::UI_RPC_FIELD,
 };
 
@@ -53,10 +59,12 @@ fn new_actor_uuid() -> String {
 pub struct LoginQuery {
     #[serde(default)]
     pub return_to: Option<String>,
+    #[serde(default)]
+    pub error: Option<String>,
 }
 
 #[derive(Debug, Deserialize)]
-pub struct GitHubStartQuery {
+pub struct OAuthStartQuery {
     #[serde(default)]
     pub return_to: Option<String>,
     #[serde(default)]
@@ -72,15 +80,22 @@ fn return_from_query_or_jar(jar: &CookieJar, query: Option<&str>) -> String {
         .unwrap_or_else(|| "/".to_string())
 }
 
-fn oauth_providers(base_url: &str, return_to: &str) -> Vec<(&'static str, String)> {
+/// Available OAuth link targets: `(provider_key, label, start_href)`.
+fn oauth_providers(base_url: &str, return_to: &str) -> Vec<(&'static str, &'static str, String)> {
     let mut out = Vec::new();
+    let enc = urlencoding::encode(return_to);
     if oauth::GitHubConfig::from_env(base_url).is_some() {
         out.push((
-            "GitHub",
-            format!(
-                "/auth/github?return_to={}",
-                urlencoding::encode(return_to)
-            ),
+            "github",
+            oauth::provider_label("github"),
+            format!("/auth/github?return_to={enc}"),
+        ));
+    }
+    if oauth::RedditConfig::from_env(base_url).is_some() {
+        out.push((
+            "reddit",
+            oauth::provider_label("reddit"),
+            format!("/auth/reddit?return_to={enc}"),
         ));
     }
     out
@@ -125,23 +140,41 @@ fn alias_claim_forms(return_to: &str, submit_label: &str) -> Result<Markup, Stat
     })
 }
 
-fn signed_out_body(providers: &[(&str, String)]) -> Markup {
+fn login_error_message(code: Option<&str>) -> Option<&'static str> {
+    match code {
+        Some("oauth_taken") => {
+            Some("that OAuth account is already linked to a different sorter2 account")
+        }
+        Some("oauth_failed") => Some("OAuth failed — try again"),
+        _ => None,
+    }
+}
+
+fn signed_out_body(
+    providers: &[(&str, &str, String)],
+    error: Option<&str>,
+) -> Markup {
     html! {
         main class="panel login-page" {
             section class="login-section" {
                 h1 { "sign in" }
-                p class="muted" { "link an account to vote under a lasting alias" }
+                p class="muted" {
+                    "link an OAuth account to create your identity, then claim an alias to vote"
+                }
+                @if let Some(msg) = login_error_message(error) {
+                    p class="alias-bad" data-testid="login-error" { (msg) }
+                }
                 @if providers.is_empty() {
                     p class="muted" {
-                        "OAuth is not configured. Set GITHUB_CLIENT_ID and GITHUB_CLIENT_SECRET."
+                        "OAuth is not configured. Set GitHub and/or Reddit client credentials."
                     }
                 } @else {
                     ul class="oauth-provider-list" {
-                        @for (name, href) in providers {
+                        @for (key, label, href) in providers {
                             li {
                                 a href=(href) class="btn-primary oauth-provider"
-                                    data-testid=(format!("oauth-{}", name.to_lowercase())) {
-                                    (format!("Continue with {name}"))
+                                    data-testid=(format!("oauth-{key}")) {
+                                    (format!("Link {label}"))
                                 }
                             }
                         }
@@ -156,7 +189,10 @@ fn signed_out_body(providers: &[(&str, String)]) -> Markup {
 fn account_body(
     actor: &session::SessionActor,
     aliases: &[String],
-    providers: &[(&str, String)],
+    // Provider keys already linked to this UUID (private).
+    linked: &[String],
+    // Providers available to link: not yet attached.
+    unlinkable: &[(&str, &str, String)],
     claim_forms: Markup,
 ) -> Markup {
     let current = actor.pseudonym.trim();
@@ -212,16 +248,29 @@ fn account_body(
                 (claim_forms)
             }
 
-            @if !providers.is_empty() {
-                section class="login-section" {
-                    h2 { "linked sign-in" }
-                    p class="muted small" { "sign in again with the same provider to return to this account" }
+            section class="login-section" {
+                h2 { "linked sign-in" }
+                p class="muted small" {
+                    "private to you — linking more providers raises trust weight without publishing which accounts you use"
+                }
+                @if linked.is_empty() {
+                    p class="muted" data-testid="linked-providers-empty" { "none yet" }
+                } @else {
+                    ul class="linked-provider-list" data-testid="linked-providers" {
+                        @for key in linked {
+                            li data-testid=(format!("linked-{key}")) {
+                                (oauth::provider_label(key))
+                            }
+                        }
+                    }
+                }
+                @if !unlinkable.is_empty() {
                     ul class="oauth-provider-list" {
-                        @for (name, href) in providers {
+                        @for (key, label, href) in unlinkable {
                             li {
                                 a href=(href) class="btn-secondary oauth-provider"
-                                    data-testid=(format!("oauth-relink-{}", name.to_lowercase())) {
-                                    (format!("Re-link {name}"))
+                                    data-testid=(format!("oauth-link-{key}")) {
+                                    (format!("Link {label}"))
                                 }
                             }
                         }
@@ -243,12 +292,21 @@ fn account_body(
 fn login_body(
     session: Option<&session::SessionActor>,
     aliases: &[String],
-    providers: &[(&str, String)],
+    linked: &[String],
+    providers: &[(&str, &str, String)],
     claim_forms: Option<Markup>,
+    error: Option<&str>,
 ) -> Markup {
     match (session, claim_forms) {
-        (Some(actor), Some(forms)) => account_body(actor, aliases, providers, forms),
-        _ => signed_out_body(providers),
+        (Some(actor), Some(forms)) => {
+            let unlinkable: Vec<_> = providers
+                .iter()
+                .filter(|(key, _, _)| !linked.iter().any(|p| p == key))
+                .cloned()
+                .collect();
+            account_body(actor, aliases, linked, &unlinkable, forms)
+        }
+        _ => signed_out_body(providers, error),
     }
 }
 
@@ -268,6 +326,10 @@ pub async fn login_page(
         .as_ref()
         .map(|s| alias_list(db, &s.uuid))
         .unwrap_or_default();
+    let linked = session
+        .as_ref()
+        .map(|s| linked_providers_for_uuid(db, &s.uuid).unwrap_or_default())
+        .unwrap_or_default();
     let providers = oauth_providers(&base_url_from_env(state.cfg.port), &return_to);
 
     let claim_forms = if session.is_some() {
@@ -282,7 +344,14 @@ pub async fn login_page(
         } else {
             "login · sorter2"
         },
-        login_body(session.as_ref(), &aliases, &providers, claim_forms),
+        login_body(
+            session.as_ref(),
+            &aliases,
+            &linked,
+            &providers,
+            claim_forms,
+            query.error.as_deref(),
+        ),
         state.views.get_views("/login"),
         session
             .as_ref()
@@ -302,7 +371,6 @@ pub async fn alias_page(
     let db = state.projection_store.db();
     let session = session::load_valid_session(db, &session_id).ok_or(StatusCode::UNAUTHORIZED)?;
     if session::session_has_pseudonym(&session) {
-        // Already onboarded — manage aliases on the account page.
         return Ok(Redirect::to("/login").into_response());
     }
 
@@ -331,7 +399,7 @@ pub async fn alias_page(
 pub async fn github_start(
     State(state): State<AppState>,
     jar: CookieJar,
-    Query(query): Query<GitHubStartQuery>,
+    Query(query): Query<OAuthStartQuery>,
 ) -> Result<Response, StatusCode> {
     let cfg = oauth::GitHubConfig::from_env(&base_url_from_env(state.cfg.port))
         .ok_or(StatusCode::SERVICE_UNAVAILABLE)?;
@@ -342,7 +410,28 @@ pub async fn github_start(
     } else {
         None
     };
-    let url = oauth::authorize_url(&cfg, &state_token, mock_user);
+    let url = oauth::github_authorize_url(&cfg, &state_token, mock_user);
+    let jar = jar
+        .add(session::oauth_state_cookie_value(&state_token))
+        .add(session::auth_return_cookie_value(&return_to));
+    Ok((jar, Redirect::temporary(&url)).into_response())
+}
+
+pub async fn reddit_start(
+    State(state): State<AppState>,
+    jar: CookieJar,
+    Query(query): Query<OAuthStartQuery>,
+) -> Result<Response, StatusCode> {
+    let cfg = oauth::RedditConfig::from_env(&base_url_from_env(state.cfg.port))
+        .ok_or(StatusCode::SERVICE_UNAVAILABLE)?;
+    let return_to = return_from_query_or_jar(&jar, query.return_to.as_deref());
+    let state_token = session::new_oauth_state();
+    let mock_user = if config::mock_oauth_allowed() {
+        query.mock_user.as_deref()
+    } else {
+        None
+    };
+    let url = oauth::reddit_authorize_url(&cfg, &state_token, mock_user);
     let jar = jar
         .add(session::oauth_state_cookie_value(&state_token))
         .add(session::auth_return_cookie_value(&return_to));
@@ -355,6 +444,13 @@ pub struct OAuthCallbackQuery {
     pub state: String,
 }
 
+/// Link `provider:provider_id` to a UUID.
+///
+/// - Logged in + new provider → attach to session UUID
+/// - Logged in + already ours → no-op
+/// - Logged in + owned by someone else → conflict
+/// - Logged out + known link → resume that UUID
+/// - Logged out + unknown → create principal + first link
 async fn finish_oauth_login(
     state: &AppState,
     jar: CookieJar,
@@ -364,11 +460,41 @@ async fn finish_oauth_login(
     let db = state.projection_store.db();
     let return_to = return_from_query_or_jar(&jar, None);
 
-    let uuid = match oauth_link_owner(db, provider, &provider_id)
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?
-    {
-        Some(existing) => existing,
-        None => {
+    let existing_owner = oauth_link_owner(db, provider, &provider_id)
+        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+
+    let session_uuid = session::session_id_from_jar(&jar)
+        .as_deref()
+        .and_then(|id| session::load_valid_session(db, id))
+        .map(|s| s.uuid);
+    let linking_while_logged_in = session_uuid.is_some();
+
+    let uuid = match (session_uuid, existing_owner) {
+        (Some(session_uuid), Some(owner)) if owner == session_uuid => session_uuid,
+        (Some(_), Some(_)) => {
+            return Ok((
+                jar.add(session::clear_oauth_state_cookie()),
+                "/login?error=oauth_taken".into(),
+            ));
+        }
+        (Some(session_uuid), None) => {
+            let ts = now_ms();
+            state
+                .append_identity_events(vec![Event::OauthLinked {
+                    uuid: session_uuid.clone(),
+                    provider: provider.to_string(),
+                    provider_id,
+                    ts,
+                }])
+                .await
+                .map_err(|e| {
+                    tracing::warn!(err = %e, "oauth link append failed");
+                    StatusCode::INTERNAL_SERVER_ERROR
+                })?;
+            session_uuid
+        }
+        (None, Some(owner)) => owner,
+        (None, None) => {
             let uuid = new_actor_uuid();
             let ts = now_ms();
             state
@@ -409,6 +535,9 @@ async fn finish_oauth_login(
             "/login/alias?return_to={}",
             urlencoding::encode(&return_to)
         )
+    } else if linking_while_logged_in {
+        // Additional link while already in an account → stay on account page.
+        "/login".to_string()
     } else {
         return_to
     };
@@ -434,22 +563,57 @@ pub async fn github_callback(
         .build()
         .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
 
-    let token = oauth::exchange_code(&client, &cfg, &query.code)
+    let token = oauth::github_exchange_code(&client, &cfg, &query.code)
         .await
         .map_err(|e| {
             tracing::warn!(err = %e, "github oauth token exchange failed");
             StatusCode::BAD_GATEWAY
         })?;
-    let user = oauth::fetch_user(&client, &cfg.api_base, &token)
+    let user = oauth::github_fetch_user(&client, &cfg.api_base, &token)
         .await
         .map_err(|e| {
             tracing::warn!(err = %e, "github user fetch failed");
             StatusCode::BAD_GATEWAY
         })?;
 
-    let provider = "github";
-    let provider_id = oauth::provider_id(&user);
-    let (jar, dest) = finish_oauth_login(&state, jar, provider, provider_id).await?;
+    let (jar, dest) =
+        finish_oauth_login(&state, jar, "github", oauth::github_provider_id(&user)).await?;
+    Ok((jar, Redirect::to(&dest)).into_response())
+}
+
+pub async fn reddit_callback(
+    State(state): State<AppState>,
+    jar: CookieJar,
+    Query(query): Query<OAuthCallbackQuery>,
+) -> Result<Response, StatusCode> {
+    let cfg = oauth::RedditConfig::from_env(&base_url_from_env(state.cfg.port))
+        .ok_or(StatusCode::SERVICE_UNAVAILABLE)?;
+
+    let expected_state = session::oauth_state_from_jar(&jar).ok_or(StatusCode::BAD_REQUEST)?;
+    if expected_state != query.state {
+        return Err(StatusCode::BAD_REQUEST);
+    }
+
+    let client = Client::builder()
+        .timeout(std::time::Duration::from_secs(15))
+        .build()
+        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+
+    let token = oauth::reddit_exchange_code(&client, &cfg, &query.code)
+        .await
+        .map_err(|e| {
+            tracing::warn!(err = %e, "reddit oauth token exchange failed");
+            StatusCode::BAD_GATEWAY
+        })?;
+    let user = oauth::reddit_fetch_user(&client, &cfg, &token)
+        .await
+        .map_err(|e| {
+            tracing::warn!(err = %e, "reddit user fetch failed");
+            StatusCode::BAD_GATEWAY
+        })?;
+
+    let (jar, dest) =
+        finish_oauth_login(&state, jar, "reddit", oauth::reddit_provider_id(&user)).await?;
     Ok((jar, Redirect::to(&dest)).into_response())
 }
 
diff --git a/server/src/auth/oauth.rs b/server/src/auth/oauth.rs
index b80078fee0c5acd905b9125d29454e46c4e0d066..369b1527d9032cf312a07819279e0f988ef4a36e 100644
--- a/server/src/auth/oauth.rs
+++ b/server/src/auth/oauth.rs
@@ -1,8 +1,15 @@
-//! GitHub OAuth (raw reqwest, same style as reddit.rs).
+//! OAuth providers (GitHub + Reddit). Provider accounts only *link* to a UUID;
+//! the UUID is the canonical identity. Which providers are linked is private.
 
 use reqwest::Client;
 use serde::Deserialize;
 
+use crate::reddit::{
+    default_user_agent, reddit_oauth_api_base, reddit_oauth_token_base,
+};
+
+// ── GitHub ──────────────────────────────────────────────────────────────────
+
 #[derive(Debug, Clone)]
 pub struct GitHubConfig {
     pub client_id: String,
@@ -40,7 +47,7 @@ impl GitHubConfig {
 }
 
 #[derive(Debug, Deserialize)]
-struct TokenResponse {
+struct GitHubTokenResponse {
     access_token: String,
 }
 
@@ -50,7 +57,7 @@ pub struct GitHubUser {
     pub login: String,
 }
 
-pub fn authorize_url(cfg: &GitHubConfig, state: &str, mock_user: Option<&str>) -> String {
+pub fn github_authorize_url(cfg: &GitHubConfig, state: &str, mock_user: Option<&str>) -> String {
     let mut url = format!(
         "{}/login/oauth/authorize?client_id={}&redirect_uri={}&scope=read:user&state={}",
         cfg.oauth_base.trim_end_matches('/'),
@@ -65,7 +72,7 @@ pub fn authorize_url(cfg: &GitHubConfig, state: &str, mock_user: Option<&str>) -
     url
 }
 
-pub async fn exchange_code(
+pub async fn github_exchange_code(
     client: &Client,
     cfg: &GitHubConfig,
     code: &str,
@@ -90,14 +97,14 @@ pub async fn exchange_code(
         return Err(format!("github token HTTP {}", resp.status()));
     }
 
-    let body: TokenResponse = resp
+    let body: GitHubTokenResponse = resp
         .json()
         .await
         .map_err(|e| format!("github token parse failed: {e}"))?;
     Ok(body.access_token)
 }
 
-pub async fn fetch_user(
+pub async fn github_fetch_user(
     client: &Client,
     api_base: &str,
     access_token: &str,
@@ -120,10 +127,149 @@ pub async fn fetch_user(
         .map_err(|e| format!("github user parse failed: {e}"))
 }
 
-pub fn provider_id(user: &GitHubUser) -> String {
+pub fn github_provider_id(user: &GitHubUser) -> String {
     user.id.to_string()
 }
 
+// ── Reddit ──────────────────────────────────────────────────────────────────
+
+#[derive(Debug, Clone)]
+pub struct RedditConfig {
+    pub client_id: String,
+    pub client_secret: String,
+    pub redirect_uri: String,
+    /// Host for `/api/v1/authorize` (www.reddit.com in production).
+    pub authorize_base: String,
+    /// Host for `POST /api/v1/access_token`.
+    pub token_base: String,
+    /// Host for bearer `GET /api/v1/me` (oauth.reddit.com).
+    pub api_base: String,
+    pub user_agent: String,
+}
+
+/// Authorize page base; defaults to the same host as token POSTs.
+pub fn reddit_authorize_base() -> String {
+    std::env::var("REDDIT_OAUTH_AUTHORIZE_BASE")
+        .or_else(|_| std::env::var("REDDIT_OAUTH_BASE"))
+        .unwrap_or_else(|_| "https://www.reddit.com".into())
+}
+
+impl RedditConfig {
+    pub fn from_env(base_url: &str) -> Option<Self> {
+        let client_id = std::env::var("REDDIT_CLIENT_ID")
+            .or_else(|_| std::env::var("REDDIT_APP_ID"))
+            .ok()?;
+        let client_secret = std::env::var("REDDIT_CLIENT_SECRET")
+            .or_else(|_| std::env::var("REDDIT_APP_SECRET"))
+            .ok()?;
+        if client_id.is_empty() || client_secret.is_empty() {
+            return None;
+        }
+        let base = base_url.trim_end_matches('/');
+        Some(Self {
+            client_id,
+            client_secret,
+            redirect_uri: format!("{base}/auth/reddit/callback"),
+            authorize_base: reddit_authorize_base(),
+            token_base: reddit_oauth_token_base(),
+            api_base: reddit_oauth_api_base(),
+            user_agent: default_user_agent(),
+        })
+    }
+}
+
+#[derive(Debug, Deserialize)]
+struct RedditTokenResponse {
+    access_token: String,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct RedditUser {
+    /// Stable id (`t2_…`); never use `name` as identity.
+    pub id: String,
+    pub name: String,
+}
+
+pub fn reddit_authorize_url(cfg: &RedditConfig, state: &str, mock_user: Option<&str>) -> String {
+    let mut url = format!(
+        "{}/api/v1/authorize?client_id={}&response_type=code&state={}&redirect_uri={}&duration=temporary&scope=identity",
+        cfg.authorize_base.trim_end_matches('/'),
+        urlencoding::encode(&cfg.client_id),
+        urlencoding::encode(state),
+        urlencoding::encode(&cfg.redirect_uri),
+    );
+    if let Some(user) = mock_user {
+        url.push_str("&mock_user=");
+        url.push_str(&urlencoding::encode(user));
+    }
+    url
+}
+
+pub async fn reddit_exchange_code(
+    client: &Client,
+    cfg: &RedditConfig,
+    code: &str,
+) -> Result<String, String> {
+    let resp = client
+        .post(format!(
+            "{}/api/v1/access_token",
+            cfg.token_base.trim_end_matches('/')
+        ))
+        .header("User-Agent", &cfg.user_agent)
+        .basic_auth(&cfg.client_id, Some(&cfg.client_secret))
+        .form(&[
+            ("grant_type", "authorization_code"),
+            ("code", code),
+            ("redirect_uri", cfg.redirect_uri.as_str()),
+        ])
+        .send()
+        .await
+        .map_err(|e| format!("reddit token request failed: {e}"))?;
+
+    if !resp.status().is_success() {
+        let status = resp.status();
+        let body = resp.text().await.unwrap_or_default();
+        return Err(format!("reddit token HTTP {status}: {body}"));
+    }
+
+    let body: RedditTokenResponse = resp
+        .json()
+        .await
+        .map_err(|e| format!("reddit token parse failed: {e}"))?;
+    Ok(body.access_token)
+}
+
+pub async fn reddit_fetch_user(
+    client: &Client,
+    cfg: &RedditConfig,
+    access_token: &str,
+) -> Result<RedditUser, String> {
+    let resp = client
+        .get(format!(
+            "{}/api/v1/me",
+            cfg.api_base.trim_end_matches('/')
+        ))
+        .header("User-Agent", &cfg.user_agent)
+        .bearer_auth(access_token)
+        .send()
+        .await
+        .map_err(|e| format!("reddit user request failed: {e}"))?;
+
+    if !resp.status().is_success() {
+        return Err(format!("reddit user HTTP {}", resp.status()));
+    }
+
+    resp.json()
+        .await
+        .map_err(|e| format!("reddit user parse failed: {e}"))
+}
+
+pub fn reddit_provider_id(user: &RedditUser) -> String {
+    user.id.clone()
+}
+
+// ── Shared helpers ──────────────────────────────────────────────────────────
+
 pub fn validate_pseudonym(raw: &str) -> Result<String, &'static str> {
     let trimmed = raw.trim();
     if trimmed.is_empty() {
@@ -144,3 +290,12 @@ pub fn validate_pseudonym(raw: &str) -> Result<String, &'static str> {
 pub fn sanitize_pseudonym(login: &str) -> String {
     validate_pseudonym(login).unwrap_or_else(|_| "user".to_string())
 }
+
+/// Display name for a provider key (`github` → `GitHub`). Never show provider ids.
+pub fn provider_label(provider: &str) -> &'static str {
+    match provider {
+        "github" => "GitHub",
+        "reddit" => "Reddit",
+        _ => "OAuth",
+    }
+}
diff --git a/server/src/lib.rs b/server/src/lib.rs
index 84f2565b105fb302241b949af64bd5e49916eab2..0d948af1457504fdbd34d0b14261f65ac58da0ec 100644
--- a/server/src/lib.rs
+++ b/server/src/lib.rs
@@ -47,6 +47,8 @@ pub fn create_app(state: AppState) -> Router {
         .route("/login/alias", get(crate::auth::alias_page))
         .route("/auth/github", get(crate::auth::github_start))
         .route("/auth/github/callback", get(crate::auth::github_callback))
+        .route("/auth/reddit", get(crate::auth::reddit_start))
+        .route("/auth/reddit/callback", get(crate::auth::reddit_callback))
         .route("/auth/logout", post(crate::auth::logout))
         .route("/auth/switch", post(crate::auth::switch_pseudonym))
         .route("/ui", post(crate::api::ui_html::post_ui_html))
diff --git a/server/src/projection_apply.rs b/server/src/projection_apply.rs
index 4fb4b48ee0a53b7f673fae0c9731eed5acc33332..f50458c2ff3c447a3cfd28adb298e6883a2da4e9 100644
--- a/server/src/projection_apply.rs
+++ b/server/src/projection_apply.rs
@@ -4,6 +4,8 @@
 //! child links, recent-vote appends) plus a cursor advance, all committed in
 //! one atomic `DisableWal` batch.
 
+use std::collections::HashMap;
+
 use crate::{
     event_log::EventLogError,
     events::{Event, EventRecord},
@@ -44,6 +46,8 @@ pub fn apply_records(
     let db = projection_store.db();
     let mut batch = db.batch();
     let mut last_seq = 0u64;
+    // Weight reads must see earlier writes in this same batch.
+    let mut pending_weights: HashMap<String, f64> = HashMap::new();
 
     for record in records {
         match &record.event {
@@ -85,6 +89,7 @@ pub fn apply_records(
                 ensure_path_writes(&mut batch, &parsed);
             }
             Event::PrincipalCreated { uuid, .. } => {
+                pending_weights.insert(uuid.clone(), BASE_TRUST_WEIGHT);
                 batch.write(
                     Store::root()
                         .user_weights()
@@ -112,17 +117,25 @@ pub fn apply_records(
                     }
                 } else {
                     batch.write(Store::root().oauth_links().key(&link_key).set(uuid));
-                    let current = Store::root()
-                        .user_weights()
-                        .key(&uuid.clone())
-                        .get(db)
-                        .map_err(|e| EventLogError::Apply(e.to_string()))?
+                    let current = pending_weights
+                        .get(uuid)
+                        .copied()
+                        .or_else(|| {
+                            Store::root()
+                                .user_weights()
+                                .key(&uuid.clone())
+                                .get(db)
+                                .ok()
+                                .flatten()
+                        })
                         .unwrap_or(BASE_TRUST_WEIGHT);
+                    let next = trust_weight_after_link(current);
+                    pending_weights.insert(uuid.clone(), next);
                     batch.write(
                         Store::root()
                             .user_weights()
                             .key(&uuid.clone())
-                            .set(&trust_weight_after_link(current)),
+                            .set(&next),
                     );
                 }
             }
@@ -205,6 +218,15 @@ mod tests {
                 ),
                 record(
                     3,
+                    Event::OauthLinked {
+                        uuid: uuid.into(),
+                        provider: "reddit".into(),
+                        provider_id: "t2_abc".into(),
+                        ts,
+                    },
+                ),
+                record(
+                    4,
                     Event::PseudonymClaimed {
                         uuid: uuid.into(),
                         pseudonym: "octocat".into(),
@@ -219,8 +241,12 @@ mod tests {
             oauth_link_owner(store.db(), "github", "42").unwrap(),
             Some(uuid.to_string())
         );
+        assert_eq!(
+            crate::storage_schema::linked_providers_for_uuid(store.db(), uuid).unwrap(),
+            vec!["github".to_string(), "reddit".to_string()]
+        );
         assert_eq!(resolve_actor_uuid(store.db(), "octocat").unwrap(), uuid);
-        assert_eq!(user_trust_weight(store.db(), uuid).unwrap(), 1.5);
+        assert_eq!(user_trust_weight(store.db(), uuid).unwrap(), 2.0);
         let aliases = Store::root()
             .user_pseudonyms()
             .key(&uuid.to_string())
diff --git a/server/src/storage_schema.rs b/server/src/storage_schema.rs
index b942810afd96d3bf01b7765718303a39be4ef8d2..dac6f8e6080e3f5683c24dbb8861f5a981d456c4 100644
--- a/server/src/storage_schema.rs
+++ b/server/src/storage_schema.rs
@@ -103,6 +103,25 @@ pub fn oauth_link_owner(db: &Db, provider: &str, provider_id: &str) -> durable::
         .get(db)
 }
 
+/// Provider names linked to a UUID (`github`, `reddit`, …). Private — for the
+/// account owner's page only; never expose which providers are linked publicly.
+pub fn linked_providers_for_uuid(db: &Db, uuid: &str) -> durable::Result<Vec<String>> {
+    let mut providers = Vec::new();
+    for (key, owner) in Store::root().oauth_links().iter(db)? {
+        if owner != uuid {
+            continue;
+        }
+        let Some((provider, _)) = key.split_once(':') else {
+            continue;
+        };
+        if !providers.iter().any(|p| p == provider) {
+            providers.push(provider.to_string());
+        }
+    }
+    providers.sort();
+    Ok(providers)
+}
+
 pub const RECENT_VOTES_CAP: u64 = 200;
 
 fn id_key(id: &ItemId) -> String {
diff --git a/test/support/harness.clj b/test/support/harness.clj
index 4505ece5aa193e826ca61c52f1467d252080d66b..741024aab1d14269e225791189633287980ae2e4 100644
--- a/test/support/harness.clj
+++ b/test/support/harness.clj
@@ -48,12 +48,15 @@
          "GITHUB_CLIENT_SECRET" "test-secret"
          "GITHUB_OAUTH_BASE" (str "http://127.0.0.1:" oauth-port)
          "GITHUB_API_BASE" (str "http://127.0.0.1:" oauth-port)
+         ;; Reddit import fixtures + Reddit OAuth on reddit-port.
          "REDDIT_API_BASE" (str "http://127.0.0.1:" reddit-port)
+         "REDDIT_CLIENT_ID" "test-reddit"
+         "REDDIT_CLIENT_SECRET" "test-reddit-secret"
          "REDDIT_OAUTH_BASE" (str "http://127.0.0.1:" reddit-port)
-         "REDDIT_CLIENT_ID" ""
-         "REDDIT_CLIENT_SECRET" ""
-         "REDDIT_APP_ID" ""
-         "REDDIT_APP_SECRET" ""}))
+         "REDDIT_OAUTH_AUTHORIZE_BASE" (str "http://127.0.0.1:" reddit-port)
+         "REDDIT_OAUTH_TOKEN_BASE" (str "http://127.0.0.1:" reddit-port)
+         "REDDIT_OAUTH_API_BASE" (str "http://127.0.0.1:" reddit-port)
+         "REDDIT_USER_AGENT" "web:sorter2-test:v0 (by /u/test)"}))
 
 (defn with-auth-servers
   "Start mock Reddit + mock OAuth + release sorter2-server.
diff --git a/test/support/mock_oauth.clj b/test/support/mock_oauth.clj
index 909d7a7be8b159ea54a122d69c46af3db3318118..5ba7e9be3cf6d2226648e9609a09ed45f306930f 100644
--- a/test/support/mock_oauth.clj
+++ b/test/support/mock_oauth.clj
@@ -1,5 +1,5 @@
 (ns test.support.mock-oauth
-  "In-process HTTP stub for GitHub OAuth (authorize, token, /user)."
+  "In-process HTTP stub for GitHub + Reddit OAuth (authorize, token, user)."
   (:require [clojure.string :as str])
   (:import [com.sun.net.httpserver HttpServer HttpHandler HttpExchange]
            [java.net InetSocketAddress URLDecoder]))
@@ -12,11 +12,14 @@
                 (URLDecoder/decode (or v "") "UTF-8"))))
           (str/split query #"&"))))
 
-(defn- parse-mock-user [raw]
+(defn- parse-mock-user
+  "GitHub-style `id:login` (numeric id). Reddit-style `t2_xxx:name`."
+  [raw]
   (let [s (or raw "1002:newbie")
         [id login] (str/split s #":" 2)]
-    {:id (Long/parseLong id)
-     :login (or login "newbie")}))
+    {:id id
+     :login (or login "newbie")
+     :numeric? (re-matches #"\d+" id)}))
 
 (defn- send-json [^HttpExchange ex status body]
   (let [bytes (.getBytes body "UTF-8")]
@@ -31,9 +34,10 @@
   (.sendResponseHeaders ex 302 -1)
   (.close (.getResponseBody ex)))
 
-(defn- read-form-code [^HttpExchange ex]
+(defn- read-form [^HttpExchange ex]
   (let [body (slurp (.getInputStream ex))]
-    (query-param body "code")))
+    {:code (query-param body "code")
+     :grant (query-param body "grant_type")}))
 
 (defn- bearer-token [^HttpExchange ex]
   (some-> (.getRequestHeaders ex)
@@ -44,8 +48,18 @@
   (when (str/starts-with? token "mock:")
     (parse-mock-user (subs token 5))))
 
+(defn- authorize-redirect [exchange query]
+  (let [redirect-uri (query-param query "redirect_uri")
+        state (query-param query "state")
+        mock-user (query-param query "mock_user")
+        user (parse-mock-user mock-user)
+        code (str "mock:" (:id user) ":" (:login user))
+        loc (str redirect-uri "?code=" (java.net.URLEncoder/encode code "UTF-8")
+                 "&state=" (java.net.URLEncoder/encode state "UTF-8"))]
+    (send-redirect exchange loc)))
+
 (defn start-mock-oauth
-  "Start mock GitHub OAuth on `port`. Returns a zero-arg `stop` function."
+  "Start mock GitHub + Reddit OAuth on `port`. Returns a zero-arg `stop` function."
   [port]
   (let [server (HttpServer/create (InetSocketAddress. "127.0.0.1" port) 0)
         handler
@@ -53,28 +67,45 @@
           (handle [^HttpExchange exchange]
             (let [uri (.getRequestURI exchange)
                   path (.getPath uri)
-                  query (.getQuery uri)]
+                  query (.getQuery uri)
+                  method (.getRequestMethod exchange)]
               (cond
+                ;; GitHub authorize
                 (str/ends-with? path "/login/oauth/authorize")
-                (let [redirect-uri (query-param query "redirect_uri")
-                      state (query-param query "state")
-                      mock-user (query-param query "mock_user")
-                      user (parse-mock-user mock-user)
-                      code (str "mock:" (:id user) ":" (:login user))
-                      loc (str redirect-uri "?code=" (java.net.URLEncoder/encode code "UTF-8")
-                               "&state=" (java.net.URLEncoder/encode state "UTF-8"))]
-                  (send-redirect exchange loc))
+                (authorize-redirect exchange query)
+
+                ;; Reddit authorize
+                (str/ends-with? path "/api/v1/authorize")
+                (authorize-redirect exchange query)
 
-                (str/ends-with? path "/login/oauth/access_token")
-                (let [code (or (read-form-code exchange) "mock:1002:newbie")]
+                ;; GitHub token
+                (and (= method "POST") (str/ends-with? path "/login/oauth/access_token"))
+                (let [code (or (:code (read-form exchange)) "mock:1002:newbie")]
                   (send-json exchange 200 (str "{\"access_token\":\"" code "\",\"token_type\":\"bearer\"}")))
 
+                ;; Reddit token (client_credentials for import + authorization_code for login)
+                (and (= method "POST") (str/ends-with? path "/api/v1/access_token"))
+                (let [form (read-form exchange)
+                      grant (or (:grant form) "")
+                      code (or (:code form) "mock:t2_test:redditor")]
+                  (if (= grant "client_credentials")
+                    (send-json exchange 200 "{\"access_token\":\"app-token\",\"token_type\":\"bearer\",\"expires_in\":3600}")
+                    (send-json exchange 200 (str "{\"access_token\":\"" code "\",\"token_type\":\"bearer\",\"expires_in\":3600}"))))
+
+                ;; GitHub user
                 (= path "/user")
                 (let [token (bearer-token exchange)
-                      user (or (parse-token-user token) {:id 1002 :login "newbie"})]
+                      user (or (parse-token-user token) {:id "1002" :login "newbie" :numeric? true})]
                   (send-json exchange 200
                              (str "{\"id\":" (:id user) ",\"login\":\"" (:login user) "\"}")))
 
+                ;; Reddit /api/v1/me
+                (str/ends-with? path "/api/v1/me")
+                (let [token (bearer-token exchange)
+                      user (or (parse-token-user token) {:id "t2_test" :login "redditor"})]
+                  (send-json exchange 200
+                             (str "{\"id\":\"" (:id user) "\",\"name\":\"" (:login user) "\"}")))
+
                 :else
                 (send-json exchange 404 "{\"error\":\"not found\"}")))))]
     (.createContext server "/" handler)
diff --git a/test/support/mock_reddit.clj b/test/support/mock_reddit.clj
index 5efa92db3e1f79b8f423a2f1adcbda959123c1ad..a630cf0938722193e9af88382d60e777ff371be4 100644
--- a/test/support/mock_reddit.clj
+++ b/test/support/mock_reddit.clj
@@ -1,14 +1,56 @@
 (ns test.support.mock-reddit
-  "In-process HTTP stub for Reddit API fixtures (`test/fixtures/reddit/`)."
+  "In-process HTTP stub for Reddit API fixtures + OAuth login endpoints."
   (:require [clojure.java.io :as io]
             [clojure.string :as str])
   (:import [com.sun.net.httpserver HttpServer HttpHandler HttpExchange]
-           [java.net InetSocketAddress]))
+           [java.net InetSocketAddress URLDecoder]))
 
 (defn fixtures-dir
   ([] (fixtures-dir (System/getProperty "user.dir")))
   ([root] (str root "/test/fixtures/reddit")))
 
+(defn- query-param [query key]
+  (when query
+    (some (fn [pair]
+            (let [[k v] (str/split pair "=" 2)]
+              (when (= k key)
+                (URLDecoder/decode (or v "") "UTF-8"))))
+          (str/split query #"&"))))
+
+(defn- parse-mock-user [raw]
+  (let [s (or raw "t2_test:redditor")
+        [id login] (str/split s #":" 2)]
+    {:id id :login (or login "redditor")}))
+
+(defn- send-bytes [^HttpExchange ex status ^bytes body content-type]
+  (.set (.getResponseHeaders ex) "Content-Type" content-type)
+  (.sendResponseHeaders ex status (alength body))
+  (doto (.getResponseBody ex)
+    (.write body)
+    (.close)))
+
+(defn- send-json [^HttpExchange ex status body]
+  (send-bytes ex status (.getBytes body "UTF-8") "application/json"))
+
+(defn- send-redirect [^HttpExchange ex location]
+  (.set (.getResponseHeaders ex) "Location" location)
+  (.sendResponseHeaders ex 302 -1)
+  (.close (.getResponseBody ex)))
+
+(defn- read-form [^HttpExchange ex]
+  (let [body (slurp (.getInputStream ex))]
+    {:code (query-param body "code")
+     :grant (query-param body "grant_type")}))
+
+(defn- bearer-token [^HttpExchange ex]
+  (some-> (.getRequestHeaders ex)
+          (.getFirst "Authorization")
+          (str/replace #"^[Bb]earer " "")))
+
+(defn- parse-token-user [token]
+  (when (str/starts-with? token "mock:")
+    (parse-mock-user (subs token 5))))
+
 (defn start-mock-reddit
   "Start a mock Reddit API on `port`. Returns a zero-arg `stop` function."
   ([port] (start-mock-reddit port (fixtures-dir)))
@@ -19,15 +61,38 @@
          handler
          (proxy [HttpHandler] []
            (handle [^HttpExchange exchange]
-             ;; `/r/<sub>/about.json` → subreddit entity; `/r/<sub>.json` → listing.
-             (let [path (.getPath (.getRequestURI exchange))
-                   body (if (str/includes? path "/about")
-                          about
-                          listing)]
-               (.sendResponseHeaders exchange 200 (alength body))
-               (let [out (.getResponseBody exchange)]
-                 (.write out body)
-                 (.close out)))))]
+             (let [uri (.getRequestURI exchange)
+                   path (.getPath uri)
+                   query (.getQuery uri)
+                   method (.getRequestMethod exchange)]
+               (cond
+                 (str/ends-with? path "/api/v1/authorize")
+                 (let [redirect-uri (query-param query "redirect_uri")
+                       state (query-param query "state")
+                       user (parse-mock-user (query-param query "mock_user"))
+                       code (str "mock:" (:id user) ":" (:login user))
+                       loc (str redirect-uri "?code=" (java.net.URLEncoder/encode code "UTF-8")
+                                "&state=" (java.net.URLEncoder/encode state "UTF-8"))]
+                   (send-redirect exchange loc))
+
+                 (and (= method "POST") (str/ends-with? path "/api/v1/access_token"))
+                 (let [form (read-form exchange)
+                       grant (or (:grant form) "")
+                       code (or (:code form) "mock:t2_test:redditor")]
+                   (if (= grant "client_credentials")
+                     (send-json exchange 200 "{\"access_token\":\"app-token\",\"token_type\":\"bearer\",\"expires_in\":3600}")
+                     (send-json exchange 200 (str "{\"access_token\":\"" code "\",\"token_type\":\"bearer\",\"expires_in\":3600}"))))
+
+                 (str/ends-with? path "/api/v1/me")
+                 (let [user (or (parse-token-user (bearer-token exchange))
+                                {:id "t2_test" :login "redditor"})]
+                   (send-json exchange 200
+                              (str "{\"id\":\"" (:id user) "\",\"name\":\"" (:login user) "\"}")))
+
+                 ;; `/r/<sub>/about.json` → subreddit entity; `/r/<sub>.json` → listing.
+                 :else
+                 (let [body (if (str/includes? path "/about") about listing)]
+                   (send-bytes exchange 200 body "application/json"))))))]
      (.createContext server "/" handler)
      (.setExecutor server nil)
      (.start server)