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:
[07715165] nice

Side A — unified diff (full patch):
diff --git a/server/src/api/ui_html.rs b/server/src/api/ui_html.rs
index c3c62a76f424010d77a6090c84dd0b82098f573e..da2536112faea313352624cf2ce0ddd0ab3377c1 100644
--- a/server/src/api/ui_html.rs
+++ b/server/src/api/ui_html.rs
@@ -6,7 +6,7 @@ use axum::{
 use std::collections::HashMap;
 
 use crate::{
-    html::{demo_counter_panel, js_string_literal, ranking_panel, JsBuilder},
+    html::{js_string_literal, ranking_panel, JsBuilder},
     parser::parse_reddit_url,
     parser_render::parser_panel_morph,
     state::AppState,
@@ -35,13 +35,6 @@ pub async fn post_ui_html(
     };
 
     match action {
-        HtmlUiAction::BumpDemoCounter => {
-            let count = state.bump_demo_counter().await;
-            let panel = demo_counter_panel(count, state.event_log.path().to_string_lossy().as_ref());
-            JsBuilder::new()
-                .morph_selector("#demo-counter-panel", panel)
-                .into_response()
-        }
         HtmlUiAction::RecordVote {
             a,
             b,
@@ -54,8 +47,8 @@ pub async fn post_ui_html(
             {
                 return ui_js_warn(&e).into_response();
             }
-            let mut group = state.group.write().await;
-            let panel = ranking_panel(&mut group);
+            let group = state.group.read().await;
+            let panel = ranking_panel(&group);
             JsBuilder::new()
                 .morph_selector("#ranking-panel", panel)
                 .into_response()
@@ -87,20 +80,6 @@ mod tests {
         assert!(matches!(err, HtmlUiParseError::MissingRpc));
     }
 
-    #[test]
-    fn bump_action_deserializes() {
-        let template = serde_json::json!({ "action": "bump_demo_counter" });
-        let mut form = HashMap::new();
-        form.insert(
-            UI_RPC_FIELD.to_string(),
-            serde_json::to_string(&template).unwrap(),
-        );
-        assert_eq!(
-            parse_html_ui_from_form(&form).unwrap(),
-            HtmlUiAction::BumpDemoCounter
-        );
-    }
-
     #[test]
     fn record_vote_action_deserializes() {
         let template = serde_json::json!({
diff --git a/server/src/events.rs b/server/src/events.rs
index b969242534e184d4f0a689543a479670b08a18df..eff80aef0257f706d2341f666e63d6a3d921bf6e 100644
--- a/server/src/events.rs
+++ b/server/src/events.rs
@@ -5,8 +5,6 @@ use serde::{Deserialize, Serialize};
 pub enum Event {
     /// Page view recorded (path → counter in views.json).
     ViewRecorded { path: String, ts: i64 },
-    /// Demo counter bump from `POST /ui` (persisted in the single JSONL log).
-    DemoCounterBumped { ts: i64, value: u64 },
     /// Pairwise comparison vote (replayed into [`crate::reducer::GroupState`] on boot).
     VoteRecorded {
         ts: i64,
diff --git a/server/src/html/mod.rs b/server/src/html/mod.rs
index 5b1d0b5a887d89e7e80796aa7a6c8ed5baaf2782..d69ed962b5c8625bc83c933b1825f2cc1d0868e2 100644
--- a/server/src/html/mod.rs
+++ b/server/src/html/mod.rs
@@ -13,7 +13,7 @@ use crate::{
     form_template::template_json_compact,
     parser_action::ParserAction,
     parser_render::parser_panel,
-    ranking::ranked_items,
+    ranking::ranked_items_cached,
     reducer::GroupState,
     state::AppState,
     ui_action::UI_RPC_FIELD,
@@ -199,10 +199,8 @@ fn layout(title: &str, body: Markup, views: u64, theme: &str, theme_next: &str)
     }
 }
 
-pub fn ranking_panel(group: &mut GroupState) -> Markup {
-    const MAX_ITERS: usize = 10_000;
-    const TOL: f64 = 1e-8;
-    let items = ranked_items(group, MAX_ITERS, TOL);
+pub fn ranking_panel(group: &GroupState) -> Markup {
+    let items = ranked_items_cached(group);
     html! {
         section id="ranking-panel" class="demo-panel" {
             h2 { "Ranking" }
@@ -260,35 +258,6 @@ pub fn vote_panel() -> Markup {
 }
 
 
-pub fn demo_counter_panel(count: u64, event_log_path: &str) -> Markup {
-    let rpc = template_json_compact(&serde_json::json!({ "action": "bump_demo_counter" }))
-        .expect("rpc json");
-    html! {
-        section id="demo-counter-panel" class="demo-panel" {
-            h1 { "sorter2" }
-            p class="muted" {
-                "Pairwise ranking scaffold — votes persist to JSONL and replay on boot."
-            }
-            p class="demo-count" {
-                strong { "Counter: " }
-                span id="demo-count-value" { (count) }
-            }
-            p class="muted small" {
-                "Event log: " code { (event_log_path) }
-            }
-            form method="post" action="/ui" id="demo-bump-form" {
-                input type="hidden" name=(UI_RPC_FIELD) value=(rpc);
-                button type="submit" class="btn-primary" { "Bump (POST /ui → eval JS)" }
-            }
-            p class="muted small" {
-                "Uses hidden "
-                code { "__rpc__" }
-                " JSON + Idiomorph morph — no full page reload."
-            }
-        }
-    }
-}
-
 pub async fn home(
     State(state): State<AppState>,
     jar: CookieJar,
@@ -297,16 +266,15 @@ pub async fn home(
     let path = uri.path().to_string();
     state.views.increment(path.clone());
     let views = state.views.get_views(&path);
-    let count = *state.demo_counter.read().await;
     let theme = theme_from_jar(&jar);
     let theme_next = theme_next_from_uri(&uri);
-    let mut group = state.group.write().await;
+    let group = state.group.read().await;
     let empty_action = ParserAction::suggest(String::new(), None);
     let body = html! {
+        h1 { "sorter2" }
         (parser_panel("", &empty_action))
         (vote_panel())
-        (ranking_panel(&mut group))
-        (demo_counter_panel(count, state.event_log.path().to_string_lossy().as_ref()))
+        (ranking_panel(&group))
     };
     layout("sorter2", body, views, theme, &theme_next)
 }
diff --git a/server/src/lib.rs b/server/src/lib.rs
index 6716c5b282e7980a7a0f03d63ad8b25eda61cc55..fa423640d598f4ba97a5885d228e78d7b97f7a22 100644
--- a/server/src/lib.rs
+++ b/server/src/lib.rs
@@ -9,6 +9,7 @@ pub mod parser_render;
 pub mod path_types;
 pub mod ranking;
 pub mod reducer;
+pub mod settlement;
 pub mod state;
 pub mod ui_action;
 pub mod views;
diff --git a/server/src/ranking.rs b/server/src/ranking.rs
index 89d3280126a8d8f841721ce8cb63ff735d68752a..2d706762792ba9239bb3f1c2e4974a2fde908013 100644
--- a/server/src/ranking.rs
+++ b/server/src/ranking.rs
@@ -91,6 +91,11 @@ pub fn compute_group_ranking(group: &mut GroupState, max_iters: usize, tol: f64)
 
 pub fn ranked_items(group: &mut GroupState, max_iters: usize, tol: f64) -> Vec<RankedItem> {
     compute_group_ranking(group, max_iters, tol);
+    ranked_items_cached(group)
+}
+
+/// Read cached scores without recomputing (HTTP fast path).
+pub fn ranked_items_cached(group: &GroupState) -> Vec<RankedItem> {
     let mut items: Vec<RankedItem> = group
         .idx_to_item
         .iter()
@@ -105,7 +110,12 @@ pub fn ranked_items(group: &mut GroupState, max_iters: usize, tol: f64) -> Vec<R
     items
 }
 
-fn compute_scores_from_edges(n: usize, edges: impl Iterator<Item = ((usize, usize), f64)>, max_iters: usize, tol: f64) -> Vec<f64> {
+pub fn compute_scores_from_edges(
+    n: usize,
+    edges: impl Iterator<Item = ((usize, usize), f64)>,
+    max_iters: usize,
+    tol: f64,
+) -> Vec<f64> {
     if n == 0 {
         return vec![];
     }
diff --git a/server/src/settlement.rs b/server/src/settlement.rs
new file mode 100644
index 0000000000000000000000000000000000000000..1f722ceaea62cda22c28ab71551f259fbf049b81
--- /dev/null
+++ b/server/src/settlement.rs
@@ -0,0 +1,114 @@
+use std::sync::Arc;
+
+use tokio::sync::{mpsc, oneshot, RwLock};
+
+use crate::{
+    event_log::EventLog,
+    events::Event,
+    ranking::compute_scores_from_edges,
+    reducer::{GroupState, VoteData},
+};
+
+const MAX_ITERS: usize = 10_000;
+const TOL: f64 = 1e-8;
+
+pub struct SettlementCommand {
+    pub vote: VoteData,
+    pub event: Event,
+    pub reply: oneshot::Sender<Result<(), String>>,
+}
+
+#[derive(Clone)]
+pub struct SettlementClient {
+    tx: mpsc::Sender<SettlementCommand>,
+}
+
+impl SettlementClient {
+    pub fn spawn(group: Arc<RwLock<GroupState>>, event_log: Arc<EventLog>) -> Self {
+        let (tx, rx) = mpsc::channel(64);
+        tokio::spawn(settlement_worker(rx, group, event_log));
+        Self { tx }
+    }
+
+    pub async fn record_vote(&self, vote: VoteData, event: Event) -> Result<(), String> {
+        let (reply, rx) = oneshot::channel();
+        self.tx
+            .send(SettlementCommand {
+                vote,
+                event,
+                reply,
+            })
+            .await
+            .map_err(|_| "settlement worker stopped".to_string())?;
+        rx.await
+            .map_err(|_| "settlement worker stopped".to_string())?
+    }
+}
+
+async fn settlement_worker(
+    mut rx: mpsc::Receiver<SettlementCommand>,
+    group: Arc<RwLock<GroupState>>,
+    event_log: Arc<EventLog>,
+) {
+    while let Some(first) = rx.recv().await {
+        let mut batch = vec![first];
+        while let Ok(more) = rx.try_recv() {
+            batch.push(more);
+        }
+
+        let mut disk_err: Option<String> = None;
+        for cmd in &batch {
+            if let Err(e) = event_log.append(&cmd.event).await {
+                disk_err = Some(e.to_string());
+                break;
+            }
+        }
+
+        if let Some(err) = disk_err {
+            for cmd in batch {
+                let _ = cmd.reply.send(Err(err.clone()));
+            }
+            continue;
+        }
+
+        let (edges, n) = {
+            let mut w = group.write().await;
+            for cmd in &batch {
+                w.apply_vote(cmd.vote.clone());
+            }
+            (w.edges.clone(), w.idx_to_item.len())
+        };
+
+        let new_scores = compute_scores_from_edges(
+            n,
+            edges.iter().map(|(&k, &v)| (k, v)),
+            MAX_ITERS,
+            TOL,
+        );
+
+        {
+            let mut w = group.write().await;
+            w.cached_scores = new_scores;
+            w.dirty = false;
+        }
+
+        for cmd in batch {
+            let _ = cmd.reply.send(Ok(()));
+        }
+    }
+}
+
+/// Compute ranking cache from current in-memory edges (startup replay only).
+pub fn warm_ranking_cache(group: &mut GroupState) {
+    if !group.dirty {
+        return;
+    }
+    let n = group.idx_to_item.len();
+    group.cached_scores = compute_scores_from_edges(
+        n,
+        group.edges.iter().map(|(&k, &v)| (k, v)),
+        MAX_ITERS,
+        TOL,
+    );
+    group.dirty = false;
+}
diff --git a/server/src/state.rs b/server/src/state.rs
index 8ec9902e2ecc31cf8208f7ad6365891dc5537eed..1922541a4064c2de1df2d993a461cae783320e05 100644
--- a/server/src/state.rs
+++ b/server/src/state.rs
@@ -6,6 +6,7 @@ use crate::{
     event_log::EventLog,
     events::Event,
     reducer::{GroupState, VoteData},
+    settlement::{warm_ranking_cache, SettlementClient},
     views::ViewStore,
 };
 
@@ -38,8 +39,8 @@ pub struct AppState {
     pub cfg: Arc<AppConfig>,
     pub event_log: Arc<EventLog>,
     pub views: ViewStore,
-    pub demo_counter: Arc<RwLock<u64>>,
     pub group: Arc<RwLock<GroupState>>,
+    settlement: SettlementClient,
 }
 
 impl AppState {
@@ -48,14 +49,10 @@ impl AppState {
         let views_path = format!("{}/views.json", cfg.data_dir);
         let views = ViewStore::new(&views_path);
 
-        let mut demo_counter: u64 = 0;
         let mut group = GroupState::new();
         if let Ok((events, _)) = event_log.load_all().await {
             for ev in events {
                 match ev {
-                    Event::DemoCounterBumped { value, .. } => {
-                        demo_counter = demo_counter.max(value);
-                    }
                     Event::VoteRecorded {
                         ts,
                         a,
@@ -74,30 +71,20 @@ impl AppState {
             }
         }
 
+        warm_ranking_cache(&mut group);
+
+        let group = Arc::new(RwLock::new(group));
+        let settlement = SettlementClient::spawn(group.clone(), event_log.clone());
+
         Self {
             cfg: Arc::new(cfg),
             event_log,
             views,
-            demo_counter: Arc::new(RwLock::new(demo_counter)),
-            group: Arc::new(RwLock::new(group)),
+            group,
+            settlement,
         }
     }
 
-    pub async fn bump_demo_counter(&self) -> u64 {
-        let mut guard = self.demo_counter.write().await;
-        *guard += 1;
-        let value = *guard;
-        drop(guard);
-
-        let ts = crate::html::now_ms();
-        let _ = self
-            .event_log
-            .append(&Event::DemoCounterBumped { ts, value })
-            .await;
-
-        value
-    }
-
     pub async fn record_vote(
         &self,
         a: &str,
@@ -109,23 +96,14 @@ impl AppState {
         let vote = VoteData::from_recorded(ts, a, b, ratio_left, ratio_right)
             .ok_or_else(|| "invalid vote: need two distinct non-empty items".to_string())?;
 
-        {
-            let mut group = self.group.write().await;
-            group.apply_vote(vote.clone());
-        }
-
-        let _ = self
-            .event_log
-            .append(&Event::VoteRecorded {
-                ts,
-                a: vote.a.as_str().to_string(),
-                b: vote.b.as_str().to_string(),
-                ratio_left: vote.ratio_left,
-                ratio_right: vote.ratio_right,
-            })
-            .await
-            .map_err(|e| e.to_string())?;
+        let event = Event::VoteRecorded {
+            ts,
+            a: vote.a.as_str().to_string(),
+            b: vote.b.as_str().to_string(),
+            ratio_left: vote.ratio_left,
+            ratio_right: vote.ratio_right,
+        };
 
-        Ok(())
+        self.settlement.record_vote(vote, event).await
     }
 }
diff --git a/server/src/ui_action.rs b/server/src/ui_action.rs
index 1d488e1ad1d8fd81bd9d016d69255adfe9b22fc8..5d94c84113607b3bcd8d31d03ef5b8e1b87b67a7 100644
--- a/server/src/ui_action.rs
+++ b/server/src/ui_action.rs
@@ -12,8 +12,6 @@ pub const UI_RPC_FIELD: &str = "__rpc__";
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
 #[serde(tag = "action", rename_all = "snake_case")]
 pub enum HtmlUiAction {
-    /// Demo: morph `#demo-counter-panel` after bumping the persisted counter.
-    BumpDemoCounter,
     /// Record a pairwise vote and morph `#ranking-panel`.
     RecordVote {
         a: String,
@@ -52,18 +50,6 @@ pub fn parse_html_ui_from_form(
 mod tests {
     use super::*;
 
-    #[test]
-    fn bump_demo_counter_round_trip() {
-        let template = serde_json::json!({ "action": "bump_demo_counter" });
-        let mut form = HashMap::new();
-        form.insert(
-            UI_RPC_FIELD.to_string(),
-            serde_json::to_string(&template).unwrap(),
-        );
-        let a = parse_html_ui_from_form(&form).unwrap();
-        assert_eq!(a, HtmlUiAction::BumpDemoCounter);
-    }
-
     #[test]
     fn record_vote_round_trip_with_form_holes() {
         let template = serde_json::json!({
diff --git a/server/tests/integration_health.rs b/server/tests/integration_health.rs
index 8a58bc14aac68c779e7ce4ffa57d27b3220e9953..1d816e008b9bf629967e3b3c786c41afefc284e3 100644
--- a/server/tests/integration_health.rs
+++ b/server/tests/integration_health.rs
@@ -38,7 +38,7 @@ async fn healthz_ok() {
 }
 
 #[tokio::test]
-async fn home_has_demo_panel() {
+async fn home_has_main_panels() {
     let (addr, _tmp) = start_test_server().await;
     let client = reqwest::Client::new();
     let html = client
diff --git a/server/tests/integration_ui.rs b/server/tests/integration_ui.rs
index bee79407dec120699a083f1a75adf9291e207fc7..7ede46d681fefbe25b1d98fc33520a185515eb1c 100644
--- a/server/tests/integration_ui.rs
+++ b/server/tests/integration_ui.rs
@@ -25,33 +25,6 @@ async fn start_test_server() -> (SocketAddr, TempDir) {
     (addr, tmp)
 }
 
-#[tokio::test]
-async fn post_ui_bump_returns_javascript_morph() {
-    let (addr, tmp) = start_test_server().await;
-    let rpc = serde_json::json!({ "action": "bump_demo_counter" }).to_string();
-    let mut form = HashMap::new();
-    form.insert(UI_RPC_FIELD.to_string(), rpc);
-
-    let client = reqwest::Client::new();
-    let body = client
-        .post(format!("http://{addr}/ui"))
-        .form(&form)
-        .send()
-        .await
-        .unwrap()
-        .text()
-        .await
-        .unwrap();
-
-    assert!(body.contains("Idiomorph.morph"));
-    assert!(body.contains("demo-counter-panel"));
-    assert!(body.contains("Counter:"));
-
-    let log_path = tmp.path().join("events.jsonl");
-    let log = std::fs::read_to_string(log_path).unwrap();
-    assert!(log.contains("demo_counter_bumped"));
-}
-
 #[tokio::test]
 async fn post_ui_record_vote_morphs_ranking_and_persists() {
     let (addr, tmp) = start_test_server().await;
@@ -90,8 +63,8 @@ async fn post_ui_record_vote_morphs_ranking_and_persists() {
         port: 0,
     };
     let state = create_app_state(cfg).await;
-    let mut group = state.group.write().await;
-    let ranked = sorter2_server::ranking::ranked_items(&mut group, 10_000, 1e-8);
+    let group = state.group.read().await;
+    let ranked = sorter2_server::ranking::ranked_items_cached(&group);
     assert_eq!(ranked.len(), 2);
     assert_eq!(ranked[0].item.as_str(), "alpha");
 }
diff --git a/test/smoke.clj b/test/smoke.clj
index b332324743b58baf3fe96d7477353749f137feae..11887c48282088e140d823a88ba616f6325835b3 100644
--- a/test/smoke.clj
+++ b/test/smoke.clj
@@ -26,7 +26,7 @@
             false))))))
 
 (deftest http-smoke-against-running-server
-  (testing "build, start, healthz, home contains RPC demo"
+  (testing "build, start, healthz, home contains main panels"
     (let [root (repo-root)
           data-dir (.getAbsolutePath (doto (io/file (System/getProperty "java.io.tmpdir")
                                                    (str "sorter2-smoke-" (System/currentTimeMillis)))


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)