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:
[880eb778] Harden auth: fail-closed votes, mock OAuth gate, Secure cookies.

Also show the current alias in the top nav and pin durable by rev.

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

Side A — unified diff (full patch):
diff --git a/AGENTS.md b/AGENTS.md
index babb889d6fbfb1fa7176c9e6b7544ae17b61dd2e..6e0fd8ebb65d665c9c1438e3275971d62b98fd95 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -10,11 +10,11 @@ Single Rust web app **`sorter2-server`**: pairwise voting, rank-centrality ranki
 
 - **Bootstrap script**: `./scripts/cursor-env-install.sh` (also run via `.cursor/environment.json` on Cloud Agent boot) installs Playwright Chromium, Babashka, bbin, `clj-paren-repair`, and warms the RocksDB build.
 - **Rust 1.88+** is required (`rust-toolchain.toml`). The Cloud Dockerfile and `cursor-env-install.sh` install **rustup** 1.88.0 first so `cargo` works while Playwright/Clojure bootstrap continues. Do not rely on `/usr/local/cargo` (often missing or stale).
-- **RocksDB / `durable`**: Ubuntu’s default `c++` is often **clang** without libc++ headers. Set **`CXX=g++`** and **`RUSTFLAGS="-C linker=g++"`** (or `CC=gcc`) before `cargo build` / `cargo test` — both are set in the bootstrap script and `.cursor/environment.json`.
+- **RocksDB / `durable`**: `durable` is an external git dependency (`tommy-mor/durable`, pinned by rev in `server/Cargo.toml`). Ubuntu’s default `c++` is often **clang** without libc++ headers. Set **`CXX=g++`** and **`RUSTFLAGS="-C linker=g++"`** (or `CC=gcc`) before `cargo build` / `cargo test` — both are set in the bootstrap script and `.cursor/environment.json`.
 - **System packages** for builds: `build-essential`, `g++`, `clang`, `libclang-dev`, `pkg-config`, `libssl-dev`, `openjdk-21-jre-headless` (for `reqwest` / OpenSSL, `librocksdb-sys`, `zstd-sys` / bindgen, and **bbin** / Clojure JVM). The bootstrap sets **`JAVA_HOME`** when Java is present.
 - **Clojure CLI 1.12.0.1530** (used in CI): install from https://clojure.org/guides/install_clojure — needed for `./scripts/clj-test.sh` / Kaocha tests.
 - **Babashka / bbin / clj-paren-repair**: installed by `cursor-env-install.sh` into `~/.local/bin` (bb tasks in `bb.edn`, delimiter repair for Clojure edits).
-- **Playwright** (Spel browser tests in `test/vote_compare.clj`): Chromium via `clojure -M -e "(com.microsoft.playwright.CLI/main ...)"` — run once after clone or use the bootstrap script.
+- **Playwright** (Spel browser tests in `test/vote_compare.clj` / `test/auth_login.clj`): Chromium via `clojure -M -e "(com.microsoft.playwright.CLI/main ...)"` — run once after clone or use the bootstrap script.
 
 ### Commands (see also `TEST.sh`)
 
@@ -34,13 +34,17 @@ Environment variables (defaults in `server/src/state.rs`):
 - `PORT` — default `8080`
 - `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)
 
 Health check: `GET /healthz` → `ok`.
 
-Core UI flow: `POST /ui` with form field `__rpc__` (JSON). Example vote:
+Core UI flow: `POST /ui` with form field `__rpc__` (JSON). Votes require a session cookie (sign in via `/login`). Example vote:
 
 ```bash
 curl -sf -X POST http://127.0.0.1:8080/ui \
+  --cookie "sorter2_session=..." \
   --data-urlencode '__rpc__={"action":"record_vote","a":"alpha","b":"beta","ratio_left":2,"ratio_right":1}'
 ```
 
diff --git a/Cargo.lock b/Cargo.lock
index aa02997ad85777195f135bfd9456bcee0fc9a590..1f8690f3e486d099577a32c2ece48caf57ea7160 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -414,7 +414,7 @@ dependencies = [
 [[package]]
 name = "durable"
 version = "0.2.0"
-source = "git+https://github.com/tommy-mor/durable.git?branch=main#a6c14eaa809693140eea0c22b07ef24d8e74adaf"
+source = "git+https://github.com/tommy-mor/durable.git?rev=a6c14eaa809693140eea0c22b07ef24d8e74adaf#a6c14eaa809693140eea0c22b07ef24d8e74adaf"
 dependencies = [
  "ciborium",
  "durable-derive",
@@ -426,7 +426,7 @@ dependencies = [
 [[package]]
 name = "durable-derive"
 version = "0.2.0"
-source = "git+https://github.com/tommy-mor/durable.git?branch=main#a6c14eaa809693140eea0c22b07ef24d8e74adaf"
+source = "git+https://github.com/tommy-mor/durable.git?rev=a6c14eaa809693140eea0c22b07ef24d8e74adaf#a6c14eaa809693140eea0c22b07ef24d8e74adaf"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/server/Cargo.toml b/server/Cargo.toml
index dfa39beddecfa37dcdeaa602cb30f4b547528fbb..bd88687fb0ba47d68f2c08eb5e11d0e08b7c4398 100644
--- a/server/Cargo.toml
+++ b/server/Cargo.toml
@@ -25,7 +25,7 @@ futures-util = { version = "0.3", default-features = false, features = ["std"] }
 rand = "0.8"
 urlencoding = "2"
 url = "2"
-durable = { git = "https://github.com/tommy-mor/durable.git", branch = "main" }
+durable = { git = "https://github.com/tommy-mor/durable.git", rev = "a6c14eaa809693140eea0c22b07ef24d8e74adaf" }
 
 [dev-dependencies]
 reqwest = { version = "0.12", features = ["json"] }
diff --git a/server/src/api/ui_html.rs b/server/src/api/ui_html.rs
index b86581b1f337650564274254d840e8a75b49524d..9da62ffbed07eb28729aa3160bf33b07ce0d7945 100644
--- a/server/src/api/ui_html.rs
+++ b/server/src/api/ui_html.rs
@@ -71,10 +71,16 @@ pub async fn post_ui_html(
                 return resp;
             }
             let parent = parent_from_scope(&scope);
-            let actor = resolve_vote_actor(
+            let actor = match resolve_vote_actor(
                 state.projection_store.db(),
                 session_id_from_jar(&jar).as_deref(),
-            );
+            ) {
+                Ok(actor) => actor,
+                Err(_) => {
+                    return vote_auth_redirect(&state, &jar)
+                        .unwrap_or_else(|| login_redirect_js().into_response());
+                }
+            };
             if let Err(e) = state
                 .record_vote(&parent, &a, &b, ratio_left, ratio_right, &actor)
                 .await
diff --git a/server/src/auth/config.rs b/server/src/auth/config.rs
index a1f042c655bf3e5234eeb87a7d889f64592807fb..a5976af9a52ea207b35ae87bd1fe927c47a477ca 100644
--- a/server/src/auth/config.rs
+++ b/server/src/auth/config.rs
@@ -1,9 +1,42 @@
 pub const AUTH_RETURN_COOKIE: &str = "sorter2_auth_return";
 
+/// Allow `mock_user` on `/auth/github` (test harness only).
+pub fn mock_oauth_allowed() -> bool {
+    matches!(
+        std::env::var("SORTER2_ALLOW_MOCK_OAUTH").as_deref(),
+        Ok("1") | Ok("true") | Ok("TRUE")
+    )
+}
+
+/// Set the Secure flag on auth cookies when serving over HTTPS.
+pub fn cookies_secure() -> bool {
+    std::env::var("SORTER2_BASE_URL")
+        .map(|u| u.starts_with("https://"))
+        .unwrap_or(false)
+}
+
 pub fn sanitize_return_to(raw: &str) -> String {
     let s = raw.trim();
-    if s.is_empty() || !s.starts_with('/') || s.starts_with("//") {
+    if s.is_empty() || !s.starts_with('/') || s.starts_with("//") || s.starts_with("/\\") {
+        return "/".to_string();
+    }
+    // Reject scheme-relative and protocol-smuggling forms.
+    if s.contains("://") || s.contains('\\') {
         return "/".to_string();
     }
     s.to_string()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn sanitize_return_to_blocks_open_redirects() {
+        assert_eq!(sanitize_return_to(""), "/");
+        assert_eq!(sanitize_return_to("//evil.com"), "/");
+        assert_eq!(sanitize_return_to("/\\evil.com"), "/");
+        assert_eq!(sanitize_return_to("https://evil.com"), "/");
+        assert_eq!(sanitize_return_to("/vote?parent=x"), "/vote?parent=x");
+    }
+}
diff --git a/server/src/auth/mod.rs b/server/src/auth/mod.rs
index 5ed535ba199fa736f0048c32623b14c3b1e5de2d..d4a85ef52c15dc35148e4c743f0d646cbbdb056d 100644
--- a/server/src/auth/mod.rs
+++ b/server/src/auth/mod.rs
@@ -26,7 +26,7 @@ use crate::{
     ui_action::UI_RPC_FIELD,
 };
 
-pub use session::{resolve_vote_actor, session_id_from_jar, VoteActor};
+pub use session::{nav_pseudonym, resolve_vote_actor, session_id_from_jar, VoteActor};
 
 pub fn base_url_from_env(port: u16) -> String {
     std::env::var("SORTER2_BASE_URL")
@@ -168,6 +168,10 @@ pub async fn login_page(
         "login · sorter2",
         login_body(session.as_ref(), &aliases, &providers),
         state.views.get_views("/login"),
+        session
+            .as_ref()
+            .filter(|s| !s.pseudonym.trim().is_empty())
+            .map(|s| s.pseudonym.as_str()),
     );
     (jar, Html(markup.into_string())).into_response()
 }
@@ -222,6 +226,7 @@ pub async fn alias_page(
             "choose alias · sorter2",
             body,
             state.views.get_views("/login/alias"),
+            None,
         )
         .into_string(),
     )
@@ -237,7 +242,12 @@ pub async fn github_start(
         .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 url = oauth::authorize_url(&cfg, &state_token, query.mock_user.as_deref());
+    let mock_user = if config::mock_oauth_allowed() {
+        query.mock_user.as_deref()
+    } else {
+        None
+    };
+    let url = oauth::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));
diff --git a/server/src/auth/session.rs b/server/src/auth/session.rs
index 09659240b9455c6fca12db5652e1d31cf8c2acfc..41df030ded3abcafc0ab3887ab769adf103f9aa0 100644
--- a/server/src/auth/session.rs
+++ b/server/src/auth/session.rs
@@ -5,7 +5,7 @@ use durable::{Db, Durability};
 use rand::Rng;
 
 use crate::{
-    auth::config::AUTH_RETURN_COOKIE,
+    auth::config::{self, AUTH_RETURN_COOKIE},
     fetch::now_ms,
     identity::{DEFAULT_ACTOR_UUID, DEFAULT_PSEUDONYM},
     storage_dto::{SessionDataV1, SESSION_DATA_VERSION},
@@ -37,6 +37,7 @@ pub struct VoteActor {
 }
 
 impl VoteActor {
+    /// Test / bench helper: seed votes as the default pseudonym without a session.
     pub fn anon() -> Self {
         Self {
             pseudonym: DEFAULT_PSEUDONYM.to_string(),
@@ -70,20 +71,51 @@ fn hex_encode(bytes: &[u8]) -> String {
     bytes.iter().map(|b| format!("{b:02x}")).collect()
 }
 
-pub fn resolve_vote_actor(db: &Db, session_id: Option<&str>) -> VoteActor {
-    let Some(session_id) = session_id else {
-        return VoteActor::anon();
-    };
-    let Ok(Some(session)) = load_session(db, session_id) else {
-        return VoteActor::anon();
-    };
-    if session.expires_at <= now_ms() {
-        return VoteActor::anon();
+fn build_cookie(name: &'static str, value: String) -> Cookie<'static> {
+    let mut builder = Cookie::build((name, value))
+        .http_only(true)
+        .same_site(SameSite::Lax)
+        .path("/");
+    if config::cookies_secure() {
+        builder = builder.secure(true);
+    }
+    builder.build()
+}
+
+fn clear_cookie(name: &'static str) -> Cookie<'static> {
+    let mut builder = Cookie::build((name, ""))
+        .http_only(true)
+        .same_site(SameSite::Lax)
+        .path("/")
+        .removal();
+    if config::cookies_secure() {
+        builder = builder.secure(true);
+    }
+    builder.build()
+}
+
+/// Resolve the vote actor from a live session. Fail-closed: never falls back to anon.
+pub fn resolve_vote_actor(db: &Db, session_id: Option<&str>) -> Result<VoteActor, &'static str> {
+    let session_id = session_id.ok_or("sign in to vote")?;
+    let session = load_valid_session(db, session_id).ok_or("session expired")?;
+    if !session_has_pseudonym(&session) {
+        return Err("choose an alias first");
     }
     let trust_weight = user_trust_weight(db, &session.uuid).unwrap_or(1.0);
-    VoteActor {
+    Ok(VoteActor {
         pseudonym: session.current_pseudonym,
         trust_weight,
+    })
+}
+
+/// Display name for the top nav, if any session is active.
+pub fn nav_pseudonym(db: &Db, jar: &CookieJar) -> Option<String> {
+    let session_id = session_id_from_jar(jar)?;
+    let session = load_valid_session(db, &session_id)?;
+    if session_has_pseudonym(&session) {
+        Some(session.current_pseudonym)
+    } else {
+        None
     }
 }
 
@@ -151,54 +183,27 @@ pub fn destroy_session(db: &Db, session_id: &str) -> Result<(), String> {
 }
 
 pub fn session_cookie_value(session_id: &str) -> Cookie<'static> {
-    Cookie::build((SESSION_COOKIE, session_id.to_string()))
-        .http_only(true)
-        .same_site(SameSite::Lax)
-        .path("/")
-        .build()
+    build_cookie(SESSION_COOKIE, session_id.to_string())
 }
 
 pub fn clear_session_cookie() -> Cookie<'static> {
-    Cookie::build((SESSION_COOKIE, ""))
-        .http_only(true)
-        .same_site(SameSite::Lax)
-        .path("/")
-        .removal()
-        .build()
+    clear_cookie(SESSION_COOKIE)
 }
 
 pub fn oauth_state_cookie_value(state: &str) -> Cookie<'static> {
-    Cookie::build((OAUTH_STATE_COOKIE, state.to_string()))
-        .http_only(true)
-        .same_site(SameSite::Lax)
-        .path("/")
-        .build()
+    build_cookie(OAUTH_STATE_COOKIE, state.to_string())
 }
 
 pub fn clear_oauth_state_cookie() -> Cookie<'static> {
-    Cookie::build((OAUTH_STATE_COOKIE, ""))
-        .http_only(true)
-        .same_site(SameSite::Lax)
-        .path("/")
-        .removal()
-        .build()
+    clear_cookie(OAUTH_STATE_COOKIE)
 }
 
 pub fn auth_return_cookie_value(return_to: &str) -> Cookie<'static> {
-    Cookie::build((AUTH_RETURN_COOKIE, return_to.to_string()))
-        .http_only(true)
-        .same_site(SameSite::Lax)
-        .path("/")
-        .build()
+    build_cookie(AUTH_RETURN_COOKIE, return_to.to_string())
 }
 
 pub fn clear_auth_return_cookie() -> Cookie<'static> {
-    Cookie::build((AUTH_RETURN_COOKIE, ""))
-        .http_only(true)
-        .same_site(SameSite::Lax)
-        .path("/")
-        .removal()
-        .build()
+    clear_cookie(AUTH_RETURN_COOKIE)
 }
 
 pub fn auth_return_from_jar(jar: &CookieJar) -> Option<String> {
@@ -213,28 +218,35 @@ pub fn oauth_state_from_jar(jar: &CookieJar) -> Option<String> {
     jar.get(OAUTH_STATE_COOKIE).map(|c| c.value().to_string())
 }
 
-pub fn actor_uuid_for_vote(db: &Db, session_id: Option<&str>) -> String {
-    let Some(session_id) = session_id else {
-        return DEFAULT_ACTOR_UUID.to_string();
-    };
-    load_session(db, session_id)
-        .ok()
-        .flatten()
-        .filter(|s| s.expires_at > now_ms())
-        .map(|s| s.uuid)
-        .unwrap_or_else(|| DEFAULT_ACTOR_UUID.to_string())
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
 
     #[test]
-    fn missing_session_falls_back_to_anon() {
+    fn missing_session_is_error() {
+        let dir = tempfile::tempdir().unwrap();
+        let db = Db::open(dir.path()).unwrap();
+        assert_eq!(resolve_vote_actor(&db, None).unwrap_err(), "sign in to vote");
+    }
+
+    #[test]
+    fn session_without_pseudonym_is_error() {
+        let dir = tempfile::tempdir().unwrap();
+        let db = Db::open(dir.path()).unwrap();
+        let (id, _) = create_session(&db, DEFAULT_ACTOR_UUID, "").unwrap();
+        assert_eq!(
+            resolve_vote_actor(&db, Some(&id)).unwrap_err(),
+            "choose an alias first"
+        );
+    }
+
+    #[test]
+    fn session_with_pseudonym_resolves() {
         let dir = tempfile::tempdir().unwrap();
         let db = Db::open(dir.path()).unwrap();
-        let actor = resolve_vote_actor(&db, None);
-        assert_eq!(actor.pseudonym, DEFAULT_PSEUDONYM);
+        let (id, _) = create_session(&db, DEFAULT_ACTOR_UUID, "alice").unwrap();
+        let actor = resolve_vote_actor(&db, Some(&id)).unwrap();
+        assert_eq!(actor.pseudonym, "alice");
         assert_eq!(actor.trust_weight, 1.0);
     }
 }
diff --git a/server/src/html/mod.rs b/server/src/html/mod.rs
index 46d18b87f1313bf0aeb29955d18f291961057509..3cc3d7bdf55b5cb5d009600f4ade1fcd201a410b 100644
--- a/server/src/html/mod.rs
+++ b/server/src/html/mod.rs
@@ -4,11 +4,13 @@ use axum::{
     http::{header, StatusCode, Uri},
     response::{IntoResponse, Response},
 };
+use axum_extra::extract::cookie::CookieJar;
 use maud::{html, Markup, DOCTYPE};
 
 use std::collections::HashSet;
 
 use crate::{
+    auth::nav_pseudonym,
     fetch::html::entity_section,
     form_template::template_json_compact,
     path_types::ItemId,
@@ -126,7 +128,7 @@ pub fn now_ms() -> i64 {
     t.as_millis() as i64
 }
 
-pub(crate) fn layout(title: &str, body: Markup, views: u64) -> Markup {
+pub(crate) fn layout(title: &str, body: Markup, views: u64, nav_user: Option<&str>) -> Markup {
     let ver = asset_version();
     let css_href = format!("/static/sorter.css?v={ver}");
     let js_src = format!("/static/sorter_ui.js?v={ver}");
@@ -145,7 +147,15 @@ pub(crate) fn layout(title: &str, body: Markup, views: u64) -> Markup {
                     span class="view-meta muted" { (views) " views" }
                 }
                 nav class="top-nav" {
-                    a href="/login" { "login" }
+                    @if let Some(name) = nav_user {
+                        span class="top-nav-user" data-testid="nav-user" { (name) }
+                        a href="/login" { "account" }
+                        form class="top-nav-logout" method="post" action="/auth/logout" data-navigate="full" {
+                            button type="submit" data-testid="nav-logout" { "log out" }
+                        }
+                    } @else {
+                        a href="/login" data-testid="nav-login" { "login" }
+                    }
                 }
                 div id="errors" {}
                 (body)
@@ -481,10 +491,11 @@ pub fn input_panel(query: &str, error: Option<&str>) -> Markup {
     }
 }
 
-async fn item_page(state: AppState, uri: Uri, item: ItemId) -> Markup {
+async fn item_page(state: AppState, uri: Uri, item: ItemId, jar: CookieJar) -> Markup {
     let path = uri.path().to_string();
     state.views.increment(path.clone());
     let views = state.views.get_views(&path);
+    let nav_user = nav_pseudonym(state.projection_store.db(), &jar);
 
     let tree = state
         .scope_tree(&item)
@@ -513,16 +524,24 @@ async fn item_page(state: AppState, uri: Uri, item: ItemId) -> Markup {
             (ranking_panel(&item, node, &tree))
         }
     };
-    layout("sorter2", body, views)
+    layout("sorter2", body, views, nav_user.as_deref())
 }
 
-pub async fn home(State(state): State<AppState>, uri: Uri) -> impl IntoResponse {
-    item_page(state, uri, ItemId::root()).await
+pub async fn home(
+    State(state): State<AppState>,
+    jar: CookieJar,
+    uri: Uri,
+) -> impl IntoResponse {
+    item_page(state, uri, ItemId::root(), jar).await
 }
 
-pub async fn browse(State(state): State<AppState>, uri: Uri) -> impl IntoResponse {
+pub async fn browse(
+    State(state): State<AppState>,
+    jar: CookieJar,
+    uri: Uri,
+) -> impl IntoResponse {
     let item = ItemId::from_browse_uri(uri.path()).unwrap_or(ItemId::root());
-    item_page(state, uri, item).await
+    item_page(state, uri, item, jar).await
 }
 
 #[cfg(test)]
diff --git a/server/src/html/vote.rs b/server/src/html/vote.rs
index 3aa00c417c89a9cab3417c650b50ed7c73f08e20..cadbec188b17a48a63b269c0e2fa2ea8ffedd7ed 100644
--- a/server/src/html/vote.rs
+++ b/server/src/html/vote.rs
@@ -4,11 +4,13 @@ use axum::{
     extract::{Query, State},
     response::{Html, IntoResponse},
 };
+use axum_extra::extract::cookie::CookieJar;
 use maud::{html, Markup};
 use serde::Deserialize;
 use std::collections::HashSet;
 
 use crate::{
+    auth::nav_pseudonym,
     fetch::html::entity_section,
     form_template::template_json_compact,
     html::{ranking_panel_with_highlights, scope_theme_style, JsBuilder},
@@ -262,6 +264,7 @@ fn suggest_next(
 
 pub async fn vote_page(
     State(state): State<AppState>,
+    jar: CookieJar,
     Query(q): Query<VoteQuery>,
 ) -> impl IntoResponse {
     let parent = parse_item_param(&q.parent);
@@ -329,8 +332,9 @@ pub async fn vote_page(
     let path = format!("/vote?parent={}", urlencoding::encode(parent.as_str()));
     state.views.increment(path.clone());
     let views = state.views.get_views(&path);
+    let nav_user = nav_pseudonym(state.projection_store.db(), &jar);
 
-    Html(layout(&title, body, views).into_string()).into_response()
+    Html(layout(&title, body, views, nav_user.as_deref()).into_string()).into_response()
 }
 
 #[cfg(test)]
diff --git a/server/static/sorter.css b/server/static/sorter.css
index e66a1e6c1acc473c8ff1ddb1e16e75a82d33741c..257280b6b490c65222e580a325b77351cac6cc6b 100644
--- a/server/static/sorter.css
+++ b/server/static/sorter.css
@@ -34,6 +34,47 @@ body {
   font-size: 0.75rem;
 }
 
+.top-nav {
+  display: flex;
+  align-items: center;
+  justify-content: flex-end;
+  gap: 0.75rem;
+  padding: 0.5rem 1rem;
+  font-size: 0.875rem;
+}
+
+.top-nav a {
+  color: var(--muted);
+  text-decoration: none;
+}
+
+.top-nav a:hover {
+  color: var(--fg);
+}
+
+.top-nav-user {
+  color: var(--fg);
+  font-weight: 600;
+}
+
+.top-nav-logout {
+  display: inline;
+  margin: 0;
+}
+
+.top-nav-logout button {
+  background: none;
+  border: none;
+  padding: 0;
+  color: var(--muted);
+  font: inherit;
+  cursor: pointer;
+}
+
+.top-nav-logout button:hover {
+  color: var(--fg);
+}
+
 .btn-primary {
   background: var(--accent);
   color: var(--accent-fg, #0f1115);
diff --git a/test/support/harness.clj b/test/support/harness.clj
index 3f05951f418258642dcacb4a10ccccc8bfbe8748..4505ece5aa193e826ca61c52f1467d252080d66b 100644
--- a/test/support/harness.clj
+++ b/test/support/harness.clj
@@ -43,6 +43,7 @@
          "SORTER2_VIEWS_LOG" (str data-dir "/views.jsonl")
          "PORT" (str app-port)
          "SORTER2_BASE_URL" (str "http://127.0.0.1:" app-port)
+         "SORTER2_ALLOW_MOCK_OAUTH" "1"
          "GITHUB_CLIENT_ID" "test-client"
          "GITHUB_CLIENT_SECRET" "test-secret"
          "GITHUB_OAUTH_BASE" (str "http://127.0.0.1:" oauth-port)


Side B — contributor: tommy-mor
Side B — commit message:
[bf118bdf] Sanitize Reddit entity body HTML before rendering.

Use ammonia at render time so untrusted selftext_html cannot execute scripts in our origin.

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

Side B — unified diff (full patch):
diff --git a/Cargo.lock b/Cargo.lock
index 3dec7cb72a182dc654a37dca8ba0b49d77504daa..0dd4fce5fb6400ae153cca4e3dbf5a5158e6d8b4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -11,6 +11,19 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "ammonia"
+version = "4.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "17e913097e1a2124b46746c980134e8c954bc17a6a59bb3fde96f088d126dde6"
+dependencies = [
+ "cssparser",
+ "html5ever",
+ "maplit",
+ "tendril",
+ "url",
+]
+
 [[package]]
 name = "anyhow"
 version = "1.0.102"
@@ -355,6 +368,29 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "460fbee9c2c2f33933d720630a6a0bac33ba7053db5344fac858d4b8952d77d5"
 
+[[package]]
+name = "cssparser"
+version = "0.35.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e901edd733a1472f944a45116df3f846f54d37e67e68640ac8bb69689aca2aa"
+dependencies = [
+ "cssparser-macros",
+ "dtoa-short",
+ "itoa",
+ "phf",
+ "smallvec",
+]
+
+[[package]]
+name = "cssparser-macros"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13b588ba4ac1a99f7f2964d24b3d896ddc6bf847ee3855dbd4366f058cfcd331"
+dependencies = [
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "deranged"
 version = "0.5.8"
@@ -381,6 +417,21 @@ version = "0.15.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1aaf95b3e5c8f23aa320147307562d361db0ae0d51242340f558153b4eb2439b"
 
+[[package]]
+name = "dtoa"
+version = "1.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4c3cf4824e2d5f025c7b531afcb2325364084a16806f6d47fbc1f5fbd9960590"
+
+[[package]]
+name = "dtoa-short"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cd1511a7b6a56299bd043a9c167a6d2bfb37bf84a6dfceaba651168adfb43c87"
+dependencies = [
+ "dtoa",
+]
+
 [[package]]
 name = "durable"
 version = "0.2.0"
@@ -482,6 +533,16 @@ dependencies = [
  "percent-encoding",
 ]
 
+[[package]]
+name = "futf"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df420e2e84819663797d1ec6544b13c5be84629e7bb00dc960d6917db2987843"
+dependencies = [
+ "mac",
+ "new_debug_unreachable",
+]
+
 [[package]]
 name = "futures-channel"
 version = "0.3.32"
@@ -614,6 +675,17 @@ version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"
 
+[[package]]
+name = "html5ever"
+version = "0.35.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "55d958c2f74b664487a2035fe1dadb032c48718a03b63f3ab0b8537db8549ed4"
+dependencies = [
+ "log",
+ "markup5ever",
+ "match_token",
+]
+
 [[package]]
 name = "http"
 version = "1.4.1"
@@ -974,6 +1046,15 @@ version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "92daf443525c4cce67b150400bc2316076100ce0b3686209eb8cf3c31612e6f0"
 
+[[package]]
+name = "lock_api"
+version = "0.4.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "224399e74b87b5f3557511d98dff8b14089b3dadafcab6bb93eab67d3aace965"
+dependencies = [
+ "scopeguard",
+]
+
 [[package]]
 name = "log"
 version = "0.4.30"
@@ -990,6 +1071,40 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "mac"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c41e0c4fef86961ac6d6f8a82609f55f31b05e4fce149ac5710e439df7619ba4"
+
+[[package]]
+name = "maplit"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3e2e65a1a2e43cfcb47a895c4c8b10d1f4a61097f9f254f183aee60cad9c651d"
+
+[[package]]
+name = "markup5ever"
+version = "0.35.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "311fe69c934650f8f19652b3946075f0fc41ad8757dbb68f1ca14e7900ecc1c3"
+dependencies = [
+ "log",
+ "tendril",
+ "web_atoms",
+]
+
+[[package]]
+name = "match_token"
+version = "0.35.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac84fd3f360fcc43dc5f5d186f02a94192761a080e8bc58621ad4d12296a58cf"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "matchers"
 version = "0.2.0"
@@ -1092,6 +1207,12 @@ dependencies = [
  "tempfile",
 ]
 
+[[package]]
+name = "new_debug_unreachable"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "650eef8c711430f1a879fdd01d4745a7deea475becfb90269c06775983bbf086"
+
 [[package]]
 name = "nom"
 version = "7.1.3"
@@ -1175,6 +1296,29 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "parking_lot"
+version = "0.12.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93857453250e3077bd71ff98b6a65ea6621a19bb0f559a85248955ac12c45a1a"
+dependencies = [
+ "lock_api",
+ "parking_lot_core",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.9.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2621685985a2ebf1c516881c026032ac7deafcda1a2c9b7850dc81e3dfcb64c1"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "redox_syscall",
+ "smallvec",
+ "windows-link",
+]
+
 [[package]]
 name = "peeking_take_while"
 version = "0.1.2"
@@ -1187,6 +1331,58 @@ version = "2.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b4f627cb1b25917193a259e49bdad08f671f8d9708acfd5fe0a8c1455d87220"
 
+[[package]]
+name = "phf"
+version = "0.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fd6780a80ae0c52cc120a26a1a42c1ae51b247a253e4e06113d23d2c2edd078"
+dependencies = [
+ "phf_macros",
+ "phf_shared",
+]
+
+[[package]]
+name = "phf_codegen"
+version = "0.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aef8048c789fa5e851558d709946d6d79a8ff88c0440c587967f8e94bfb1216a"
+dependencies = [
+ "phf_generator",
+ "phf_shared",
+]
+
+[[package]]
+name = "phf_generator"
+version = "0.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c80231409c20246a13fddb31776fb942c38553c51e871f8cbd687a4cfb5843d"
+dependencies = [
+ "phf_shared",
+ "rand 0.8.6",
+]
+
+[[package]]
+name = "phf_macros"
+version = "0.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f84ac04429c13a7ff43785d75ad27569f2951ce0ffd30a3321230db2fc727216"
+dependencies = [
+ "phf_generator",
+ "phf_shared",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "phf_shared"
+version = "0.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "67eabc2ef2a60eb7faa00097bd1ffdb5bd28e62bf39990626a582201b7a754e5"
+dependencies = [
+ "siphasher",
+]
+
 [[package]]
 name = "pin-project-lite"
 version = "0.2.17"
@@ -1223,6 +1419,12 @@ dependencies = [
  "zerocopy",
 ]
 
+[[package]]
+name = "precomputed-hash"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "925383efa346730478fb4838dbe9137d2a47675ad789c546d150a6e1dd4ab31c"
+
 [[package]]
 name = "prettyplease"
 version = "0.2.37"
@@ -1379,6 +1581,15 @@ dependencies = [
  "rand_core 0.9.5",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.5.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed2bf2547551a7053d6fdfafda3f938979645c44812fbfcda098faae3f1a362d"
+dependencies = [
+ "bitflags 2.11.1",
+]
+
 [[package]]
 name = "regex"
 version = "1.12.3"
@@ -1563,6 +1774,12 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "scopeguard"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
+
 [[package]]
 name = "security-framework"
 version = "3.7.0"
@@ -1683,6 +1900,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "siphasher"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ee5873ec9cce0195efcb7a4e9507a04cd49aec9c83d0389df45b1ef7ba2e649"
+
 [[package]]
 name = "slab"
 version = "0.4.12"
@@ -1709,6 +1932,7 @@ dependencies = [
 name = "sorter2-server"
 version = "0.0.1"
 dependencies = [
+ "ammonia",
  "async-stream",
  "axum",
  "axum-extra",
@@ -1742,6 +1966,31 @@ version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6ce2be8dc25455e1f91df71bfa12ad37d7af1092ae736f3a6cd0e37bc7810596"
 
+[[package]]
+name = "string_cache"
+version = "0.8.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bf776ba3fa74f83bf4b63c3dcbbf82173db2632ed8452cb2d891d33f459de70f"
+dependencies = [
+ "new_debug_unreachable",
+ "parking_lot",
+ "phf_shared",
+ "precomputed-hash",
+ "serde",
+]
+
+[[package]]
+name = "string_cache_codegen"
+version = "0.5.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c711928715f1fe0fe509c53b43e993a9a557babc2d0a3567d0a3006f1ac931a0"
+dependencies = [
+ "phf_generator",
+ "phf_shared",
+ "proc-macro2",
+ "quote",
+]
+
 [[package]]
 name = "subtle"
 version = "2.6.1"
@@ -1813,6 +2062,17 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "tendril"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d24a120c5fc464a3458240ee02c299ebcb9d67b5249c8848b09d639dca8d7bb0"
+dependencies = [
+ "futf",
+ "mac",
+ "utf-8",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.69"
@@ -2116,6 +2376,12 @@ version = "2.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "daf8dba3b7eb870caf1ddeed7bc9d2a049f3cfdfae7cb521b087cc33ae4c49da"
 
+[[package]]
+name = "utf-8"
+version = "0.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09cc8ee72d2a9becf2f2febe0205bbed8fc6615b7cb429ad062dc7b7ddd036a9"
+
 [[package]]
 name = "utf8_iter"
 version = "1.0.4"
@@ -2281,6 +2547,18 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "web_atoms"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57ffde1dc01240bdf9992e3205668b235e59421fd085e8a317ed98da0178d414"
+dependencies = [
+ "phf",
+ "phf_codegen",
+ "string_cache",
+ "string_cache_codegen",
+]
+
 [[package]]
 name = "windows-link"
 version = "0.2.1"
diff --git a/server/Cargo.toml b/server/Cargo.toml
index 47659ff82fbfb50972eb2b87575e80f66e572ba4..27f552c20b97ef28cdde4cb6b1a4980375135111 100644
--- a/server/Cargo.toml
+++ b/server/Cargo.toml
@@ -13,6 +13,7 @@ serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 thiserror = "1"
 maud = { version = "0.26", features = ["axum"] }
+ammonia = "4.1"
 tower = "0.5"
 tower-http = { version = "0.5", features = ["trace"] }
 tracing = "0.1"
diff --git a/server/src/fetch/html.rs b/server/src/fetch/html.rs
index dadf050515f0473943dad97df5d318032c8cb385..5b160c6b8bd216dfaf80149854aec0566cd00460 100644
--- a/server/src/fetch/html.rs
+++ b/server/src/fetch/html.rs
@@ -4,6 +4,7 @@ use maud::{html, Markup};
 
 use crate::{
     form_template::template_json_compact,
+    html::sanitize::entity_body_html,
     path_types::ItemId,
     reddit::{is_children_fetchable, is_fetchable},
     reducer::NodeState,
@@ -27,7 +28,7 @@ pub fn entity_panel(node: &NodeState) -> Markup {
                     p class="muted small" { "by " (author) }
                 }
                 @if let Some(body) = &data.body_html {
-                    div class="entity-body" { (maud::PreEscaped(body)) }
+                    div class="entity-body" { (maud::PreEscaped(entity_body_html(body))) }
                 }
             }
         }
diff --git a/server/src/html/mod.rs b/server/src/html/mod.rs
index e180a0ca542a33e2300c0a4809e6b9cfee07ecfe..a58cbbee3490a08a625cb06df06848c59a615d65 100644
--- a/server/src/html/mod.rs
+++ b/server/src/html/mod.rs
@@ -20,6 +20,7 @@ use crate::{
     ui_action::UI_RPC_FIELD,
 };
 
+pub mod sanitize;
 pub mod vote;
 
 const SORTER_CSS: &str = include_str!("../../static/sorter.css");
diff --git a/server/src/html/sanitize.rs b/server/src/html/sanitize.rs
new file mode 100644
index 0000000000000000000000000000000000000000..6685ed2535281b9fd5d65b042cbc5a11c5d4df37
--- /dev/null
+++ b/server/src/html/sanitize.rs
@@ -0,0 +1,39 @@
+//! Whitelist sanitization for untrusted HTML fragments (e.g. Reddit `selftext_html`).
+
+use std::sync::LazyLock;
+
+use ammonia::Builder;
+
+static ENTITY_BODY: LazyLock<Builder<'static>> = LazyLock::new(|| {
+    let mut b = Builder::default();
+    b.strip_comments(true);
+    b.link_rel(Some("noopener noreferrer"));
+    b
+});
+
+/// Sanitize HTML safe for embedding in our pages via [`maud::PreEscaped`].
+pub fn entity_body_html(raw: &str) -> String {
+    ENTITY_BODY.clean(raw).to_string()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::entity_body_html;
+
+    #[test]
+    fn keeps_benign_markup() {
+        assert_eq!(
+            entity_body_html("<p>release notes</p>"),
+            "<p>release notes</p>"
+        );
+    }
+
+    #[test]
+    fn strips_scripts_and_event_handlers() {
+        let raw = "<p>ok</p><script>alert(1)</script><img src=x onerror=alert(1)>";
+        let clean = entity_body_html(raw);
+        assert!(!clean.contains("<script"));
+        assert!(!clean.contains("onerror"));
+        assert!(clean.contains("<p>ok</p>"));
+    }
+}
diff --git a/server/src/render/reddit.rs b/server/src/render/reddit.rs
index c4f98fc760c32ce1b41a91bd41e97908bd198937..7f840aa33b734a31d8cf3341a0581c8bcb9bbcf3 100644
--- a/server/src/render/reddit.rs
+++ b/server/src/render/reddit.rs
@@ -3,6 +3,7 @@
 use maud::{html, Markup};
 
 use crate::{
+    html::sanitize::entity_body_html,
     path_types::ItemId,
     reducer::{EntityData, GlobalTree, NodeState},
 };
@@ -57,7 +58,7 @@ fn post_entity_card(data: &EntityData) -> Markup {
                 }
             }
             @if let Some(body) = &data.body_html {
-                div class="entity-body" { (maud::PreEscaped(body)) }
+                div class="entity-body" { (maud::PreEscaped(entity_body_html(body))) }
             }
         }
     }