{"messages":[{"content":"You are a constitutional council ranking individual git commits for ownership allocation.\n\nCompare these two commits. Decide which contributed more lasting value to the project.\n\nJudge substance, not spectacle:\n- Prefer correct, lasting design and real bugfixes over churn, formatting, renames, or generated noise.\n- Prefer clarity and necessity over sheer line count. A small precise change can beat a large diffuse one.\n- Do not favor a side merely because its patch is longer or noisier.\n- Weight what the change does for the project, not the contributor's name.\n\nReturn ONLY a JSON object: {\"winner\": \"A\" or \"B\", \"ratio\": \"N:M\", \"explanation\": \"...\"}\nThe explanation must cite concrete differences in the patches (1-3 sentences).\n\nSide A — contributor: tommy-mor\nSide A — commit message:\n[52f5c51c] Add Reddit OAuth linking and make UUID the only account identity.\n\nOAuth providers only attach to a session UUID (first link creates the\nprincipal); linked providers stay private on the account page.\n\nCo-authored-by: Cursor \n\nSide A — unified diff (full patch):\ndiff --git a/AGENTS.md b/AGENTS.md\nindex 6e0fd8ebb65d665c9c1438e3275971d62b98fd95..e9cc3173dbeb21ad0fc090ca7b407b027c7820a9 100644\n--- a/AGENTS.md\n+++ b/AGENTS.md\n@@ -35,8 +35,11 @@ Environment variables (defaults in `server/src/state.rs`):\n - `SORTER2_DATA_DIR` — default `./data` (created on startup)\n - `SORTER2_EVENT_LOG` — default `{data_dir}/events.jsonl`\n - `SORTER2_BASE_URL` — public origin (also drives Secure cookies when `https://`)\n-- `GITHUB_CLIENT_ID` / `GITHUB_CLIENT_SECRET` — GitHub OAuth (optional; login disabled if unset)\n-- `SORTER2_ALLOW_MOCK_OAUTH=1` — allow `mock_user` on `/auth/github` (tests only)\n+- `GITHUB_CLIENT_ID` / `GITHUB_CLIENT_SECRET` — GitHub OAuth linking (optional)\n+- `REDDIT_CLIENT_ID` / `REDDIT_CLIENT_SECRET` (or `REDDIT_APP_*`) — Reddit API import + OAuth linking (optional)\n+- `SORTER2_ALLOW_MOCK_OAUTH=1` — allow `mock_user` on `/auth/github` and `/auth/reddit` (tests only)\n+\n+Identity: UUID is canonical. OAuth providers only *link* to a UUID (first link creates the principal). Linked providers are private to the account owner.\n \n Health check: `GET /healthz` → `ok`.\n \ndiff --git a/server/src/auth/mod.rs b/server/src/auth/mod.rs\nindex 5906f93b13853421e96a3c37bc9d8202a47842bf..c706ae8045a811e5941f5f6c72da88f42a403a82 100644\n--- a/server/src/auth/mod.rs\n+++ b/server/src/auth/mod.rs\n@@ -1,4 +1,8 @@\n-//! GitHub OAuth login, session cookies, and vote actor resolution.\n+//! OAuth linking, session cookies, and vote actor resolution.\n+//!\n+//! Canonical identity is a UUID. OAuth providers only *link* to that UUID\n+//! (first link creates the principal; later links attach while logged in).\n+//! Which providers are linked is private to the account owner.\n \n pub mod config;\n pub mod identity;\n@@ -22,7 +26,9 @@ use crate::{\n form_template::template_json_compact,\n html::layout,\n state::AppState,\n- storage_schema::{oauth_link_owner, pseudonym_owner, Store, StoreFields},\n+ storage_schema::{\n+ linked_providers_for_uuid, oauth_link_owner, pseudonym_owner, Store, StoreFields,\n+ },\n ui_action::UI_RPC_FIELD,\n };\n \n@@ -53,10 +59,12 @@ fn new_actor_uuid() -> String {\n pub struct LoginQuery {\n #[serde(default)]\n pub return_to: Option,\n+ #[serde(default)]\n+ pub error: Option,\n }\n \n #[derive(Debug, Deserialize)]\n-pub struct GitHubStartQuery {\n+pub struct OAuthStartQuery {\n #[serde(default)]\n pub return_to: Option,\n #[serde(default)]\n@@ -72,15 +80,22 @@ fn return_from_query_or_jar(jar: &CookieJar, query: Option<&str>) -> String {\n .unwrap_or_else(|| \"/\".to_string())\n }\n \n-fn oauth_providers(base_url: &str, return_to: &str) -> Vec<(&'static str, String)> {\n+/// Available OAuth link targets: `(provider_key, label, start_href)`.\n+fn oauth_providers(base_url: &str, return_to: &str) -> Vec<(&'static str, &'static str, String)> {\n let mut out = Vec::new();\n+ let enc = urlencoding::encode(return_to);\n if oauth::GitHubConfig::from_env(base_url).is_some() {\n out.push((\n- \"GitHub\",\n- format!(\n- \"/auth/github?return_to={}\",\n- urlencoding::encode(return_to)\n- ),\n+ \"github\",\n+ oauth::provider_label(\"github\"),\n+ format!(\"/auth/github?return_to={enc}\"),\n+ ));\n+ }\n+ if oauth::RedditConfig::from_env(base_url).is_some() {\n+ out.push((\n+ \"reddit\",\n+ oauth::provider_label(\"reddit\"),\n+ format!(\"/auth/reddit?return_to={enc}\"),\n ));\n }\n out\n@@ -125,23 +140,41 @@ fn alias_claim_forms(return_to: &str, submit_label: &str) -> Result Markup {\n+fn login_error_message(code: Option<&str>) -> Option<&'static str> {\n+ match code {\n+ Some(\"oauth_taken\") => {\n+ Some(\"that OAuth account is already linked to a different sorter2 account\")\n+ }\n+ Some(\"oauth_failed\") => Some(\"OAuth failed — try again\"),\n+ _ => None,\n+ }\n+}\n+\n+fn signed_out_body(\n+ providers: &[(&str, &str, String)],\n+ error: Option<&str>,\n+) -> Markup {\n html! {\n main class=\"panel login-page\" {\n section class=\"login-section\" {\n h1 { \"sign in\" }\n- p class=\"muted\" { \"link an account to vote under a lasting alias\" }\n+ p class=\"muted\" {\n+ \"link an OAuth account to create your identity, then claim an alias to vote\"\n+ }\n+ @if let Some(msg) = login_error_message(error) {\n+ p class=\"alias-bad\" data-testid=\"login-error\" { (msg) }\n+ }\n @if providers.is_empty() {\n p class=\"muted\" {\n- \"OAuth is not configured. Set GITHUB_CLIENT_ID and GITHUB_CLIENT_SECRET.\"\n+ \"OAuth is not configured. Set GitHub and/or Reddit client credentials.\"\n }\n } @else {\n ul class=\"oauth-provider-list\" {\n- @for (name, href) in providers {\n+ @for (key, label, href) in providers {\n li {\n a href=(href) class=\"btn-primary oauth-provider\"\n- data-testid=(format!(\"oauth-{}\", name.to_lowercase())) {\n- (format!(\"Continue with {name}\"))\n+ data-testid=(format!(\"oauth-{key}\")) {\n+ (format!(\"Link {label}\"))\n }\n }\n }\n@@ -156,7 +189,10 @@ fn signed_out_body(providers: &[(&str, String)]) -> Markup {\n fn account_body(\n actor: &session::SessionActor,\n aliases: &[String],\n- providers: &[(&str, String)],\n+ // Provider keys already linked to this UUID (private).\n+ linked: &[String],\n+ // Providers available to link: not yet attached.\n+ unlinkable: &[(&str, &str, String)],\n claim_forms: Markup,\n ) -> Markup {\n let current = actor.pseudonym.trim();\n@@ -212,16 +248,29 @@ fn account_body(\n (claim_forms)\n }\n \n- @if !providers.is_empty() {\n- section class=\"login-section\" {\n- h2 { \"linked sign-in\" }\n- p class=\"muted small\" { \"sign in again with the same provider to return to this account\" }\n+ section class=\"login-section\" {\n+ h2 { \"linked sign-in\" }\n+ p class=\"muted small\" {\n+ \"private to you — linking more providers raises trust weight without publishing which accounts you use\"\n+ }\n+ @if linked.is_empty() {\n+ p class=\"muted\" data-testid=\"linked-providers-empty\" { \"none yet\" }\n+ } @else {\n+ ul class=\"linked-provider-list\" data-testid=\"linked-providers\" {\n+ @for key in linked {\n+ li data-testid=(format!(\"linked-{key}\")) {\n+ (oauth::provider_label(key))\n+ }\n+ }\n+ }\n+ }\n+ @if !unlinkable.is_empty() {\n ul class=\"oauth-provider-list\" {\n- @for (name, href) in providers {\n+ @for (key, label, href) in unlinkable {\n li {\n a href=(href) class=\"btn-secondary oauth-provider\"\n- data-testid=(format!(\"oauth-relink-{}\", name.to_lowercase())) {\n- (format!(\"Re-link {name}\"))\n+ data-testid=(format!(\"oauth-link-{key}\")) {\n+ (format!(\"Link {label}\"))\n }\n }\n }\n@@ -243,12 +292,21 @@ fn account_body(\n fn login_body(\n session: Option<&session::SessionActor>,\n aliases: &[String],\n- providers: &[(&str, String)],\n+ linked: &[String],\n+ providers: &[(&str, &str, String)],\n claim_forms: Option,\n+ error: Option<&str>,\n ) -> Markup {\n match (session, claim_forms) {\n- (Some(actor), Some(forms)) => account_body(actor, aliases, providers, forms),\n- _ => signed_out_body(providers),\n+ (Some(actor), Some(forms)) => {\n+ let unlinkable: Vec<_> = providers\n+ .iter()\n+ .filter(|(key, _, _)| !linked.iter().any(|p| p == key))\n+ .cloned()\n+ .collect();\n+ account_body(actor, aliases, linked, &unlinkable, forms)\n+ }\n+ _ => signed_out_body(providers, error),\n }\n }\n \n@@ -268,6 +326,10 @@ pub async fn login_page(\n .as_ref()\n .map(|s| alias_list(db, &s.uuid))\n .unwrap_or_default();\n+ let linked = session\n+ .as_ref()\n+ .map(|s| linked_providers_for_uuid(db, &s.uuid).unwrap_or_default())\n+ .unwrap_or_default();\n let providers = oauth_providers(&base_url_from_env(state.cfg.port), &return_to);\n \n let claim_forms = if session.is_some() {\n@@ -282,7 +344,14 @@ pub async fn login_page(\n } else {\n \"login · sorter2\"\n },\n- login_body(session.as_ref(), &aliases, &providers, claim_forms),\n+ login_body(\n+ session.as_ref(),\n+ &aliases,\n+ &linked,\n+ &providers,\n+ claim_forms,\n+ query.error.as_deref(),\n+ ),\n state.views.get_views(\"/login\"),\n session\n .as_ref()\n@@ -302,7 +371,6 @@ pub async fn alias_page(\n let db = state.projection_store.db();\n let session = session::load_valid_session(db, &session_id).ok_or(StatusCode::UNAUTHORIZED)?;\n if session::session_has_pseudonym(&session) {\n- // Already onboarded — manage aliases on the account page.\n return Ok(Redirect::to(\"/login\").into_response());\n }\n \n@@ -331,7 +399,7 @@ pub async fn alias_page(\n pub async fn github_start(\n State(state): State,\n jar: CookieJar,\n- Query(query): Query,\n+ Query(query): Query,\n ) -> Result {\n let cfg = oauth::GitHubConfig::from_env(&base_url_from_env(state.cfg.port))\n .ok_or(StatusCode::SERVICE_UNAVAILABLE)?;\n@@ -342,7 +410,28 @@ pub async fn github_start(\n } else {\n None\n };\n- let url = oauth::authorize_url(&cfg, &state_token, mock_user);\n+ let url = oauth::github_authorize_url(&cfg, &state_token, mock_user);\n+ let jar = jar\n+ .add(session::oauth_state_cookie_value(&state_token))\n+ .add(session::auth_return_cookie_value(&return_to));\n+ Ok((jar, Redirect::temporary(&url)).into_response())\n+}\n+\n+pub async fn reddit_start(\n+ State(state): State,\n+ jar: CookieJar,\n+ Query(query): Query,\n+) -> Result {\n+ let cfg = oauth::RedditConfig::from_env(&base_url_from_env(state.cfg.port))\n+ .ok_or(StatusCode::SERVICE_UNAVAILABLE)?;\n+ let return_to = return_from_query_or_jar(&jar, query.return_to.as_deref());\n+ let state_token = session::new_oauth_state();\n+ let mock_user = if config::mock_oauth_allowed() {\n+ query.mock_user.as_deref()\n+ } else {\n+ None\n+ };\n+ let url = oauth::reddit_authorize_url(&cfg, &state_token, mock_user);\n let jar = jar\n .add(session::oauth_state_cookie_value(&state_token))\n .add(session::auth_return_cookie_value(&return_to));\n@@ -355,6 +444,13 @@ pub struct OAuthCallbackQuery {\n pub state: String,\n }\n \n+/// Link `provider:provider_id` to a UUID.\n+///\n+/// - Logged in + new provider → attach to session UUID\n+/// - Logged in + already ours → no-op\n+/// - Logged in + owned by someone else → conflict\n+/// - Logged out + known link → resume that UUID\n+/// - Logged out + unknown → create principal + first link\n async fn finish_oauth_login(\n state: &AppState,\n jar: CookieJar,\n@@ -364,11 +460,41 @@ async fn finish_oauth_login(\n let db = state.projection_store.db();\n let return_to = return_from_query_or_jar(&jar, None);\n \n- let uuid = match oauth_link_owner(db, provider, &provider_id)\n- .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?\n- {\n- Some(existing) => existing,\n- None => {\n+ let existing_owner = oauth_link_owner(db, provider, &provider_id)\n+ .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;\n+\n+ let session_uuid = session::session_id_from_jar(&jar)\n+ .as_deref()\n+ .and_then(|id| session::load_valid_session(db, id))\n+ .map(|s| s.uuid);\n+ let linking_while_logged_in = session_uuid.is_some();\n+\n+ let uuid = match (session_uuid, existing_owner) {\n+ (Some(session_uuid), Some(owner)) if owner == session_uuid => session_uuid,\n+ (Some(_), Some(_)) => {\n+ return Ok((\n+ jar.add(session::clear_oauth_state_cookie()),\n+ \"/login?error=oauth_taken\".into(),\n+ ));\n+ }\n+ (Some(session_uuid), None) => {\n+ let ts = now_ms();\n+ state\n+ .append_identity_events(vec![Event::OauthLinked {\n+ uuid: session_uuid.clone(),\n+ provider: provider.to_string(),\n+ provider_id,\n+ ts,\n+ }])\n+ .await\n+ .map_err(|e| {\n+ tracing::warn!(err = %e, \"oauth link append failed\");\n+ StatusCode::INTERNAL_SERVER_ERROR\n+ })?;\n+ session_uuid\n+ }\n+ (None, Some(owner)) => owner,\n+ (None, None) => {\n let uuid = new_actor_uuid();\n let ts = now_ms();\n state\n@@ -409,6 +535,9 @@ async fn finish_oauth_login(\n \"/login/alias?return_to={}\",\n urlencoding::encode(&return_to)\n )\n+ } else if linking_while_logged_in {\n+ // Additional link while already in an account → stay on account page.\n+ \"/login\".to_string()\n } else {\n return_to\n };\n@@ -434,22 +563,57 @@ pub async fn github_callback(\n .build()\n .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;\n \n- let token = oauth::exchange_code(&client, &cfg, &query.code)\n+ let token = oauth::github_exchange_code(&client, &cfg, &query.code)\n .await\n .map_err(|e| {\n tracing::warn!(err = %e, \"github oauth token exchange failed\");\n StatusCode::BAD_GATEWAY\n })?;\n- let user = oauth::fetch_user(&client, &cfg.api_base, &token)\n+ let user = oauth::github_fetch_user(&client, &cfg.api_base, &token)\n .await\n .map_err(|e| {\n tracing::warn!(err = %e, \"github user fetch failed\");\n StatusCode::BAD_GATEWAY\n })?;\n \n- let provider = \"github\";\n- let provider_id = oauth::provider_id(&user);\n- let (jar, dest) = finish_oauth_login(&state, jar, provider, provider_id).await?;\n+ let (jar, dest) =\n+ finish_oauth_login(&state, jar, \"github\", oauth::github_provider_id(&user)).await?;\n+ Ok((jar, Redirect::to(&dest)).into_response())\n+}\n+\n+pub async fn reddit_callback(\n+ State(state): State,\n+ jar: CookieJar,\n+ Query(query): Query,\n+) -> Result {\n+ let cfg = oauth::RedditConfig::from_env(&base_url_from_env(state.cfg.port))\n+ .ok_or(StatusCode::SERVICE_UNAVAILABLE)?;\n+\n+ let expected_state = session::oauth_state_from_jar(&jar).ok_or(StatusCode::BAD_REQUEST)?;\n+ if expected_state != query.state {\n+ return Err(StatusCode::BAD_REQUEST);\n+ }\n+\n+ let client = Client::builder()\n+ .timeout(std::time::Duration::from_secs(15))\n+ .build()\n+ .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;\n+\n+ let token = oauth::reddit_exchange_code(&client, &cfg, &query.code)\n+ .await\n+ .map_err(|e| {\n+ tracing::warn!(err = %e, \"reddit oauth token exchange failed\");\n+ StatusCode::BAD_GATEWAY\n+ })?;\n+ let user = oauth::reddit_fetch_user(&client, &cfg, &token)\n+ .await\n+ .map_err(|e| {\n+ tracing::warn!(err = %e, \"reddit user fetch failed\");\n+ StatusCode::BAD_GATEWAY\n+ })?;\n+\n+ let (jar, dest) =\n+ finish_oauth_login(&state, jar, \"reddit\", oauth::reddit_provider_id(&user)).await?;\n Ok((jar, Redirect::to(&dest)).into_response())\n }\n \ndiff --git a/server/src/auth/oauth.rs b/server/src/auth/oauth.rs\nindex b80078fee0c5acd905b9125d29454e46c4e0d066..369b1527d9032cf312a07819279e0f988ef4a36e 100644\n--- a/server/src/auth/oauth.rs\n+++ b/server/src/auth/oauth.rs\n@@ -1,8 +1,15 @@\n-//! GitHub OAuth (raw reqwest, same style as reddit.rs).\n+//! OAuth providers (GitHub + Reddit). Provider accounts only *link* to a UUID;\n+//! the UUID is the canonical identity. Which providers are linked is private.\n \n use reqwest::Client;\n use serde::Deserialize;\n \n+use crate::reddit::{\n+ default_user_agent, reddit_oauth_api_base, reddit_oauth_token_base,\n+};\n+\n+// ── GitHub ──────────────────────────────────────────────────────────────────\n+\n #[derive(Debug, Clone)]\n pub struct GitHubConfig {\n pub client_id: String,\n@@ -40,7 +47,7 @@ impl GitHubConfig {\n }\n \n #[derive(Debug, Deserialize)]\n-struct TokenResponse {\n+struct GitHubTokenResponse {\n access_token: String,\n }\n \n@@ -50,7 +57,7 @@ pub struct GitHubUser {\n pub login: String,\n }\n \n-pub fn authorize_url(cfg: &GitHubConfig, state: &str, mock_user: Option<&str>) -> String {\n+pub fn github_authorize_url(cfg: &GitHubConfig, state: &str, mock_user: Option<&str>) -> String {\n let mut url = format!(\n \"{}/login/oauth/authorize?client_id={}&redirect_uri={}&scope=read:user&state={}\",\n cfg.oauth_base.trim_end_matches('/'),\n@@ -65,7 +72,7 @@ pub fn authorize_url(cfg: &GitHubConfig, state: &str, mock_user: Option<&str>) -\n url\n }\n \n-pub async fn exchange_code(\n+pub async fn github_exchange_code(\n client: &Client,\n cfg: &GitHubConfig,\n code: &str,\n@@ -90,14 +97,14 @@ pub async fn exchange_code(\n return Err(format!(\"github token HTTP {}\", resp.status()));\n }\n \n- let body: TokenResponse = resp\n+ let body: GitHubTokenResponse = resp\n .json()\n .await\n .map_err(|e| format!(\"github token parse failed: {e}\"))?;\n Ok(body.access_token)\n }\n \n-pub async fn fetch_user(\n+pub async fn github_fetch_user(\n client: &Client,\n api_base: &str,\n access_token: &str,\n@@ -120,10 +127,149 @@ pub async fn fetch_user(\n .map_err(|e| format!(\"github user parse failed: {e}\"))\n }\n \n-pub fn provider_id(user: &GitHubUser) -> String {\n+pub fn github_provider_id(user: &GitHubUser) -> String {\n user.id.to_string()\n }\n \n+// ── Reddit ──────────────────────────────────────────────────────────────────\n+\n+#[derive(Debug, Clone)]\n+pub struct RedditConfig {\n+ pub client_id: String,\n+ pub client_secret: String,\n+ pub redirect_uri: String,\n+ /// Host for `/api/v1/authorize` (www.reddit.com in production).\n+ pub authorize_base: String,\n+ /// Host for `POST /api/v1/access_token`.\n+ pub token_base: String,\n+ /// Host for bearer `GET /api/v1/me` (oauth.reddit.com).\n+ pub api_base: String,\n+ pub user_agent: String,\n+}\n+\n+/// Authorize page base; defaults to the same host as token POSTs.\n+pub fn reddit_authorize_base() -> String {\n+ std::env::var(\"REDDIT_OAUTH_AUTHORIZE_BASE\")\n+ .or_else(|_| std::env::var(\"REDDIT_OAUTH_BASE\"))\n+ .unwrap_or_else(|_| \"https://www.reddit.com\".into())\n+}\n+\n+impl RedditConfig {\n+ pub fn from_env(base_url: &str) -> Option {\n+ let client_id = std::env::var(\"REDDIT_CLIENT_ID\")\n+ .or_else(|_| std::env::var(\"REDDIT_APP_ID\"))\n+ .ok()?;\n+ let client_secret = std::env::var(\"REDDIT_CLIENT_SECRET\")\n+ .or_else(|_| std::env::var(\"REDDIT_APP_SECRET\"))\n+ .ok()?;\n+ if client_id.is_empty() || client_secret.is_empty() {\n+ return None;\n+ }\n+ let base = base_url.trim_end_matches('/');\n+ Some(Self {\n+ client_id,\n+ client_secret,\n+ redirect_uri: format!(\"{base}/auth/reddit/callback\"),\n+ authorize_base: reddit_authorize_base(),\n+ token_base: reddit_oauth_token_base(),\n+ api_base: reddit_oauth_api_base(),\n+ user_agent: default_user_agent(),\n+ })\n+ }\n+}\n+\n+#[derive(Debug, Deserialize)]\n+struct RedditTokenResponse {\n+ access_token: String,\n+}\n+\n+#[derive(Debug, Deserialize)]\n+pub struct RedditUser {\n+ /// Stable id (`t2_…`); never use `name` as identity.\n+ pub id: String,\n+ pub name: String,\n+}\n+\n+pub fn reddit_authorize_url(cfg: &RedditConfig, state: &str, mock_user: Option<&str>) -> String {\n+ let mut url = format!(\n+ \"{}/api/v1/authorize?client_id={}&response_type=code&state={}&redirect_uri={}&duration=temporary&scope=identity\",\n+ cfg.authorize_base.trim_end_matches('/'),\n+ urlencoding::encode(&cfg.client_id),\n+ urlencoding::encode(state),\n+ urlencoding::encode(&cfg.redirect_uri),\n+ );\n+ if let Some(user) = mock_user {\n+ url.push_str(\"&mock_user=\");\n+ url.push_str(&urlencoding::encode(user));\n+ }\n+ url\n+}\n+\n+pub async fn reddit_exchange_code(\n+ client: &Client,\n+ cfg: &RedditConfig,\n+ code: &str,\n+) -> Result {\n+ let resp = client\n+ .post(format!(\n+ \"{}/api/v1/access_token\",\n+ cfg.token_base.trim_end_matches('/')\n+ ))\n+ .header(\"User-Agent\", &cfg.user_agent)\n+ .basic_auth(&cfg.client_id, Some(&cfg.client_secret))\n+ .form(&[\n+ (\"grant_type\", \"authorization_code\"),\n+ (\"code\", code),\n+ (\"redirect_uri\", cfg.redirect_uri.as_str()),\n+ ])\n+ .send()\n+ .await\n+ .map_err(|e| format!(\"reddit token request failed: {e}\"))?;\n+\n+ if !resp.status().is_success() {\n+ let status = resp.status();\n+ let body = resp.text().await.unwrap_or_default();\n+ return Err(format!(\"reddit token HTTP {status}: {body}\"));\n+ }\n+\n+ let body: RedditTokenResponse = resp\n+ .json()\n+ .await\n+ .map_err(|e| format!(\"reddit token parse failed: {e}\"))?;\n+ Ok(body.access_token)\n+}\n+\n+pub async fn reddit_fetch_user(\n+ client: &Client,\n+ cfg: &RedditConfig,\n+ access_token: &str,\n+) -> Result {\n+ let resp = client\n+ .get(format!(\n+ \"{}/api/v1/me\",\n+ cfg.api_base.trim_end_matches('/')\n+ ))\n+ .header(\"User-Agent\", &cfg.user_agent)\n+ .bearer_auth(access_token)\n+ .send()\n+ .await\n+ .map_err(|e| format!(\"reddit user request failed: {e}\"))?;\n+\n+ if !resp.status().is_success() {\n+ return Err(format!(\"reddit user HTTP {}\", resp.status()));\n+ }\n+\n+ resp.json()\n+ .await\n+ .map_err(|e| format!(\"reddit user parse failed: {e}\"))\n+}\n+\n+pub fn reddit_provider_id(user: &RedditUser) -> String {\n+ user.id.clone()\n+}\n+\n+// ── Shared helpers ──────────────────────────────────────────────────────────\n+\n pub fn validate_pseudonym(raw: &str) -> Result {\n let trimmed = raw.trim();\n if trimmed.is_empty() {\n@@ -144,3 +290,12 @@ pub fn validate_pseudonym(raw: &str) -> Result {\n pub fn sanitize_pseudonym(login: &str) -> String {\n validate_pseudonym(login).unwrap_or_else(|_| \"user\".to_string())\n }\n+\n+/// Display name for a provider key (`github` → `GitHub`). Never show provider ids.\n+pub fn provider_label(provider: &str) -> &'static str {\n+ match provider {\n+ \"github\" => \"GitHub\",\n+ \"reddit\" => \"Reddit\",\n+ _ => \"OAuth\",\n+ }\n+}\ndiff --git a/server/src/lib.rs b/server/src/lib.rs\nindex 84f2565b105fb302241b949af64bd5e49916eab2..0d948af1457504fdbd34d0b14261f65ac58da0ec 100644\n--- a/server/src/lib.rs\n+++ b/server/src/lib.rs\n@@ -47,6 +47,8 @@ pub fn create_app(state: AppState) -> Router {\n .route(\"/login/alias\", get(crate::auth::alias_page))\n .route(\"/auth/github\", get(crate::auth::github_start))\n .route(\"/auth/github/callback\", get(crate::auth::github_callback))\n+ .route(\"/auth/reddit\", get(crate::auth::reddit_start))\n+ .route(\"/auth/reddit/callback\", get(crate::auth::reddit_callback))\n .route(\"/auth/logout\", post(crate::auth::logout))\n .route(\"/auth/switch\", post(crate::auth::switch_pseudonym))\n .route(\"/ui\", post(crate::api::ui_html::post_ui_html))\ndiff --git a/server/src/projection_apply.rs b/server/src/projection_apply.rs\nindex 4fb4b48ee0a53b7f673fae0c9731eed5acc33332..f50458c2ff3c447a3cfd28adb298e6883a2da4e9 100644\n--- a/server/src/projection_apply.rs\n+++ b/server/src/projection_apply.rs\n@@ -4,6 +4,8 @@\n //! child links, recent-vote appends) plus a cursor advance, all committed in\n //! one atomic `DisableWal` batch.\n \n+use std::collections::HashMap;\n+\n use crate::{\n event_log::EventLogError,\n events::{Event, EventRecord},\n@@ -44,6 +46,8 @@ pub fn apply_records(\n let db = projection_store.db();\n let mut batch = db.batch();\n let mut last_seq = 0u64;\n+ // Weight reads must see earlier writes in this same batch.\n+ let mut pending_weights: HashMap = HashMap::new();\n \n for record in records {\n match &record.event {\n@@ -85,6 +89,7 @@ pub fn apply_records(\n ensure_path_writes(&mut batch, &parsed);\n }\n Event::PrincipalCreated { uuid, .. } => {\n+ pending_weights.insert(uuid.clone(), BASE_TRUST_WEIGHT);\n batch.write(\n Store::root()\n .user_weights()\n@@ -112,17 +117,25 @@ pub fn apply_records(\n }\n } else {\n batch.write(Store::root().oauth_links().key(&link_key).set(uuid));\n- let current = Store::root()\n- .user_weights()\n- .key(&uuid.clone())\n- .get(db)\n- .map_err(|e| EventLogError::Apply(e.to_string()))?\n+ let current = pending_weights\n+ .get(uuid)\n+ .copied()\n+ .or_else(|| {\n+ Store::root()\n+ .user_weights()\n+ .key(&uuid.clone())\n+ .get(db)\n+ .ok()\n+ .flatten()\n+ })\n .unwrap_or(BASE_TRUST_WEIGHT);\n+ let next = trust_weight_after_link(current);\n+ pending_weights.insert(uuid.clone(), next);\n batch.write(\n Store::root()\n .user_weights()\n .key(&uuid.clone())\n- .set(&trust_weight_after_link(current)),\n+ .set(&next),\n );\n }\n }\n@@ -205,6 +218,15 @@ mod tests {\n ),\n record(\n 3,\n+ Event::OauthLinked {\n+ uuid: uuid.into(),\n+ provider: \"reddit\".into(),\n+ provider_id: \"t2_abc\".into(),\n+ ts,\n+ },\n+ ),\n+ record(\n+ 4,\n Event::PseudonymClaimed {\n uuid: uuid.into(),\n pseudonym: \"octocat\".into(),\n@@ -219,8 +241,12 @@ mod tests {\n oauth_link_owner(store.db(), \"github\", \"42\").unwrap(),\n Some(uuid.to_string())\n );\n+ assert_eq!(\n+ crate::storage_schema::linked_providers_for_uuid(store.db(), uuid).unwrap(),\n+ vec![\"github\".to_string(), \"reddit\".to_string()]\n+ );\n assert_eq!(resolve_actor_uuid(store.db(), \"octocat\").unwrap(), uuid);\n- assert_eq!(user_trust_weight(store.db(), uuid).unwrap(), 1.5);\n+ assert_eq!(user_trust_weight(store.db(), uuid).unwrap(), 2.0);\n let aliases = Store::root()\n .user_pseudonyms()\n .key(&uuid.to_string())\ndiff --git a/server/src/storage_schema.rs b/server/src/storage_schema.rs\nindex b942810afd96d3bf01b7765718303a39be4ef8d2..dac6f8e6080e3f5683c24dbb8861f5a981d456c4 100644\n--- a/server/src/storage_schema.rs\n+++ b/server/src/storage_schema.rs\n@@ -103,6 +103,25 @@ pub fn oauth_link_owner(db: &Db, provider: &str, provider_id: &str) -> durable::\n .get(db)\n }\n \n+/// Provider names linked to a UUID (`github`, `reddit`, …). Private — for the\n+/// account owner's page only; never expose which providers are linked publicly.\n+pub fn linked_providers_for_uuid(db: &Db, uuid: &str) -> durable::Result> {\n+ let mut providers = Vec::new();\n+ for (key, owner) in Store::root().oauth_links().iter(db)? {\n+ if owner != uuid {\n+ continue;\n+ }\n+ let Some((provider, _)) = key.split_once(':') else {\n+ continue;\n+ };\n+ if !providers.iter().any(|p| p == provider) {\n+ providers.push(provider.to_string());\n+ }\n+ }\n+ providers.sort();\n+ Ok(providers)\n+}\n+\n pub const RECENT_VOTES_CAP: u64 = 200;\n \n fn id_key(id: &ItemId) -> String {\ndiff --git a/test/support/harness.clj b/test/support/harness.clj\nindex 4505ece5aa193e826ca61c52f1467d252080d66b..741024aab1d14269e225791189633287980ae2e4 100644\n--- a/test/support/harness.clj\n+++ b/test/support/harness.clj\n@@ -48,12 +48,15 @@\n \"GITHUB_CLIENT_SECRET\" \"test-secret\"\n \"GITHUB_OAUTH_BASE\" (str \"http://127.0.0.1:\" oauth-port)\n \"GITHUB_API_BASE\" (str \"http://127.0.0.1:\" oauth-port)\n+ ;; Reddit import fixtures + Reddit OAuth on reddit-port.\n \"REDDIT_API_BASE\" (str \"http://127.0.0.1:\" reddit-port)\n+ \"REDDIT_CLIENT_ID\" \"test-reddit\"\n+ \"REDDIT_CLIENT_SECRET\" \"test-reddit-secret\"\n \"REDDIT_OAUTH_BASE\" (str \"http://127.0.0.1:\" reddit-port)\n- \"REDDIT_CLIENT_ID\" \"\"\n- \"REDDIT_CLIENT_SECRET\" \"\"\n- \"REDDIT_APP_ID\" \"\"\n- \"REDDIT_APP_SECRET\" \"\"}))\n+ \"REDDIT_OAUTH_AUTHORIZE_BASE\" (str \"http://127.0.0.1:\" reddit-port)\n+ \"REDDIT_OAUTH_TOKEN_BASE\" (str \"http://127.0.0.1:\" reddit-port)\n+ \"REDDIT_OAUTH_API_BASE\" (str \"http://127.0.0.1:\" reddit-port)\n+ \"REDDIT_USER_AGENT\" \"web:sorter2-test:v0 (by /u/test)\"}))\n \n (defn with-auth-servers\n \"Start mock Reddit + mock OAuth + release sorter2-server.\ndiff --git a/test/support/mock_oauth.clj b/test/support/mock_oauth.clj\nindex 909d7a7be8b159ea54a122d69c46af3db3318118..5ba7e9be3cf6d2226648e9609a09ed45f306930f 100644\n--- a/test/support/mock_oauth.clj\n+++ b/test/support/mock_oauth.clj\n@@ -1,5 +1,5 @@\n (ns test.support.mock-oauth\n- \"In-process HTTP stub for GitHub OAuth (authorize, token, /user).\"\n+ \"In-process HTTP stub for GitHub + Reddit OAuth (authorize, token, user).\"\n (:require [clojure.string :as str])\n (:import [com.sun.net.httpserver HttpServer HttpHandler HttpExchange]\n [java.net InetSocketAddress URLDecoder]))\n@@ -12,11 +12,14 @@\n (URLDecoder/decode (or v \"\") \"UTF-8\"))))\n (str/split query #\"&\"))))\n \n-(defn- parse-mock-user [raw]\n+(defn- parse-mock-user\n+ \"GitHub-style `id:login` (numeric id). Reddit-style `t2_xxx:name`.\"\n+ [raw]\n (let [s (or raw \"1002:newbie\")\n [id login] (str/split s #\":\" 2)]\n- {:id (Long/parseLong id)\n- :login (or login \"newbie\")}))\n+ {:id id\n+ :login (or login \"newbie\")\n+ :numeric? (re-matches #\"\\d+\" id)}))\n \n (defn- send-json [^HttpExchange ex status body]\n (let [bytes (.getBytes body \"UTF-8\")]\n@@ -31,9 +34,10 @@\n (.sendResponseHeaders ex 302 -1)\n (.close (.getResponseBody ex)))\n \n-(defn- read-form-code [^HttpExchange ex]\n+(defn- read-form [^HttpExchange ex]\n (let [body (slurp (.getInputStream ex))]\n- (query-param body \"code\")))\n+ {:code (query-param body \"code\")\n+ :grant (query-param body \"grant_type\")}))\n \n (defn- bearer-token [^HttpExchange ex]\n (some-> (.getRequestHeaders ex)\n@@ -44,8 +48,18 @@\n (when (str/starts-with? token \"mock:\")\n (parse-mock-user (subs token 5))))\n \n+(defn- authorize-redirect [exchange query]\n+ (let [redirect-uri (query-param query \"redirect_uri\")\n+ state (query-param query \"state\")\n+ mock-user (query-param query \"mock_user\")\n+ user (parse-mock-user mock-user)\n+ code (str \"mock:\" (:id user) \":\" (:login user))\n+ loc (str redirect-uri \"?code=\" (java.net.URLEncoder/encode code \"UTF-8\")\n+ \"&state=\" (java.net.URLEncoder/encode state \"UTF-8\"))]\n+ (send-redirect exchange loc)))\n+\n (defn start-mock-oauth\n- \"Start mock GitHub OAuth on `port`. Returns a zero-arg `stop` function.\"\n+ \"Start mock GitHub + Reddit OAuth on `port`. Returns a zero-arg `stop` function.\"\n [port]\n (let [server (HttpServer/create (InetSocketAddress. \"127.0.0.1\" port) 0)\n handler\n@@ -53,28 +67,45 @@\n (handle [^HttpExchange exchange]\n (let [uri (.getRequestURI exchange)\n path (.getPath uri)\n- query (.getQuery uri)]\n+ query (.getQuery uri)\n+ method (.getRequestMethod exchange)]\n (cond\n+ ;; GitHub authorize\n (str/ends-with? path \"/login/oauth/authorize\")\n- (let [redirect-uri (query-param query \"redirect_uri\")\n- state (query-param query \"state\")\n- mock-user (query-param query \"mock_user\")\n- user (parse-mock-user mock-user)\n- code (str \"mock:\" (:id user) \":\" (:login user))\n- loc (str redirect-uri \"?code=\" (java.net.URLEncoder/encode code \"UTF-8\")\n- \"&state=\" (java.net.URLEncoder/encode state \"UTF-8\"))]\n- (send-redirect exchange loc))\n+ (authorize-redirect exchange query)\n+\n+ ;; Reddit authorize\n+ (str/ends-with? path \"/api/v1/authorize\")\n+ (authorize-redirect exchange query)\n \n- (str/ends-with? path \"/login/oauth/access_token\")\n- (let [code (or (read-form-code exchange) \"mock:1002:newbie\")]\n+ ;; GitHub token\n+ (and (= method \"POST\") (str/ends-with? path \"/login/oauth/access_token\"))\n+ (let [code (or (:code (read-form exchange)) \"mock:1002:newbie\")]\n (send-json exchange 200 (str \"{\\\"access_token\\\":\\\"\" code \"\\\",\\\"token_type\\\":\\\"bearer\\\"}\")))\n \n+ ;; Reddit token (client_credentials for import + authorization_code for login)\n+ (and (= method \"POST\") (str/ends-with? path \"/api/v1/access_token\"))\n+ (let [form (read-form exchange)\n+ grant (or (:grant form) \"\")\n+ code (or (:code form) \"mock:t2_test:redditor\")]\n+ (if (= grant \"client_credentials\")\n+ (send-json exchange 200 \"{\\\"access_token\\\":\\\"app-token\\\",\\\"token_type\\\":\\\"bearer\\\",\\\"expires_in\\\":3600}\")\n+ (send-json exchange 200 (str \"{\\\"access_token\\\":\\\"\" code \"\\\",\\\"token_type\\\":\\\"bearer\\\",\\\"expires_in\\\":3600}\"))))\n+\n+ ;; GitHub user\n (= path \"/user\")\n (let [token (bearer-token exchange)\n- user (or (parse-token-user token) {:id 1002 :login \"newbie\"})]\n+ user (or (parse-token-user token) {:id \"1002\" :login \"newbie\" :numeric? true})]\n (send-json exchange 200\n (str \"{\\\"id\\\":\" (:id user) \",\\\"login\\\":\\\"\" (:login user) \"\\\"}\")))\n \n+ ;; Reddit /api/v1/me\n+ (str/ends-with? path \"/api/v1/me\")\n+ (let [token (bearer-token exchange)\n+ user (or (parse-token-user token) {:id \"t2_test\" :login \"redditor\"})]\n+ (send-json exchange 200\n+ (str \"{\\\"id\\\":\\\"\" (:id user) \"\\\",\\\"name\\\":\\\"\" (:login user) \"\\\"}\")))\n+\n :else\n (send-json exchange 404 \"{\\\"error\\\":\\\"not found\\\"}\")))))]\n (.createContext server \"/\" handler)\ndiff --git a/test/support/mock_reddit.clj b/test/support/mock_reddit.clj\nindex 5efa92db3e1f79b8f423a2f1adcbda959123c1ad..a630cf0938722193e9af88382d60e777ff371be4 100644\n--- a/test/support/mock_reddit.clj\n+++ b/test/support/mock_reddit.clj\n@@ -1,14 +1,56 @@\n (ns test.support.mock-reddit\n- \"In-process HTTP stub for Reddit API fixtures (`test/fixtures/reddit/`).\"\n+ \"In-process HTTP stub for Reddit API fixtures + OAuth login endpoints.\"\n (:require [clojure.java.io :as io]\n [clojure.string :as str])\n (:import [com.sun.net.httpserver HttpServer HttpHandler HttpExchange]\n- [java.net InetSocketAddress]))\n+ [java.net InetSocketAddress URLDecoder]))\n \n (defn fixtures-dir\n ([] (fixtures-dir (System/getProperty \"user.dir\")))\n ([root] (str root \"/test/fixtures/reddit\")))\n \n+(defn- query-param [query key]\n+ (when query\n+ (some (fn [pair]\n+ (let [[k v] (str/split pair \"=\" 2)]\n+ (when (= k key)\n+ (URLDecoder/decode (or v \"\") \"UTF-8\"))))\n+ (str/split query #\"&\"))))\n+\n+(defn- parse-mock-user [raw]\n+ (let [s (or raw \"t2_test:redditor\")\n+ [id login] (str/split s #\":\" 2)]\n+ {:id id :login (or login \"redditor\")}))\n+\n+(defn- send-bytes [^HttpExchange ex status ^bytes body content-type]\n+ (.set (.getResponseHeaders ex) \"Content-Type\" content-type)\n+ (.sendResponseHeaders ex status (alength body))\n+ (doto (.getResponseBody ex)\n+ (.write body)\n+ (.close)))\n+\n+(defn- send-json [^HttpExchange ex status body]\n+ (send-bytes ex status (.getBytes body \"UTF-8\") \"application/json\"))\n+\n+(defn- send-redirect [^HttpExchange ex location]\n+ (.set (.getResponseHeaders ex) \"Location\" location)\n+ (.sendResponseHeaders ex 302 -1)\n+ (.close (.getResponseBody ex)))\n+\n+(defn- read-form [^HttpExchange ex]\n+ (let [body (slurp (.getInputStream ex))]\n+ {:code (query-param body \"code\")\n+ :grant (query-param body \"grant_type\")}))\n+\n+(defn- bearer-token [^HttpExchange ex]\n+ (some-> (.getRequestHeaders ex)\n+ (.getFirst \"Authorization\")\n+ (str/replace #\"^[Bb]earer \" \"\")))\n+\n+(defn- parse-token-user [token]\n+ (when (str/starts-with? token \"mock:\")\n+ (parse-mock-user (subs token 5))))\n+\n (defn start-mock-reddit\n \"Start a mock Reddit API on `port`. Returns a zero-arg `stop` function.\"\n ([port] (start-mock-reddit port (fixtures-dir)))\n@@ -19,15 +61,38 @@\n handler\n (proxy [HttpHandler] []\n (handle [^HttpExchange exchange]\n- ;; `/r//about.json` → subreddit entity; `/r/.json` → listing.\n- (let [path (.getPath (.getRequestURI exchange))\n- body (if (str/includes? path \"/about\")\n- about\n- listing)]\n- (.sendResponseHeaders exchange 200 (alength body))\n- (let [out (.getResponseBody exchange)]\n- (.write out body)\n- (.close out)))))]\n+ (let [uri (.getRequestURI exchange)\n+ path (.getPath uri)\n+ query (.getQuery uri)\n+ method (.getRequestMethod exchange)]\n+ (cond\n+ (str/ends-with? path \"/api/v1/authorize\")\n+ (let [redirect-uri (query-param query \"redirect_uri\")\n+ state (query-param query \"state\")\n+ user (parse-mock-user (query-param query \"mock_user\"))\n+ code (str \"mock:\" (:id user) \":\" (:login user))\n+ loc (str redirect-uri \"?code=\" (java.net.URLEncoder/encode code \"UTF-8\")\n+ \"&state=\" (java.net.URLEncoder/encode state \"UTF-8\"))]\n+ (send-redirect exchange loc))\n+\n+ (and (= method \"POST\") (str/ends-with? path \"/api/v1/access_token\"))\n+ (let [form (read-form exchange)\n+ grant (or (:grant form) \"\")\n+ code (or (:code form) \"mock:t2_test:redditor\")]\n+ (if (= grant \"client_credentials\")\n+ (send-json exchange 200 \"{\\\"access_token\\\":\\\"app-token\\\",\\\"token_type\\\":\\\"bearer\\\",\\\"expires_in\\\":3600}\")\n+ (send-json exchange 200 (str \"{\\\"access_token\\\":\\\"\" code \"\\\",\\\"token_type\\\":\\\"bearer\\\",\\\"expires_in\\\":3600}\"))))\n+\n+ (str/ends-with? path \"/api/v1/me\")\n+ (let [user (or (parse-token-user (bearer-token exchange))\n+ {:id \"t2_test\" :login \"redditor\"})]\n+ (send-json exchange 200\n+ (str \"{\\\"id\\\":\\\"\" (:id user) \"\\\",\\\"name\\\":\\\"\" (:login user) \"\\\"}\")))\n+\n+ ;; `/r//about.json` → subreddit entity; `/r/.json` → listing.\n+ :else\n+ (let [body (if (str/includes? path \"/about\") about listing)]\n+ (send-bytes exchange 200 body \"application/json\"))))))]\n (.createContext server \"/\" handler)\n (.setExecutor server nil)\n (.start server)\n\n\nSide B — contributor: tommy-mor\nSide B — commit message:\n[2bc302c3] refactor\n\nSide B — unified diff (full patch):\ndiff --git a/server/src/api/ui_html.rs b/server/src/api/ui_html.rs\nindex 06001212820101e0cc953d3687dea64f85e60787..d2f9769108def7ca2c5857aec8b4319426188a66 100644\n--- a/server/src/api/ui_html.rs\n+++ b/server/src/api/ui_html.rs\n@@ -47,7 +47,7 @@ pub async fn post_ui_html(\n ratio_left,\n ratio_right,\n scope,\n- next,\n+ vote_compare,\n } => {\n let parent = parent_from_scope(&scope);\n if let Err(e) = state\n@@ -57,14 +57,12 @@ pub async fn post_ui_html(\n return ui_js_warn(&e).into_response();\n }\n let tree = state.tree.read().await;\n- if !next.trim().is_empty() {\n+ if vote_compare {\n+ let left = parse_item_param(&a);\n+ let right = parse_item_param(&b);\n+ let morph = crate::html::vote::vote_recorded_morph(&tree, &parent, &left, &right);\n drop(tree);\n- return JsBuilder::new()\n- .raw(&format!(\n- \"window.location.href={};\",\n- js_string_literal(next.trim())\n- ))\n- .into_response();\n+ return morph.into_response();\n }\n let empty = crate::reducer::NodeState::default();\n let node = tree.get(&parent).unwrap_or(&empty);\n@@ -137,7 +135,7 @@ mod tests {\n ratio_left: 3,\n ratio_right: 1,\n scope: String::new(),\n- next: String::new(),\n+ vote_compare: false,\n }\n );\n }\ndiff --git a/server/src/html/mod.rs b/server/src/html/mod.rs\nindex 61cdbc094819ddedb755572c59456ec0d6617619..cd578a5fea46a9a1d49e238d08a80c2caf18708d 100644\n--- a/server/src/html/mod.rs\n+++ b/server/src/html/mod.rs\n@@ -65,6 +65,15 @@ impl JsBuilder {\n self\n }\n \n+ pub(crate) fn morph_inner_selector(mut self, selector: &str, markup: Markup) -> Self {\n+ let html = js_string_literal(&markup.into_string());\n+ self.snippets.push(format!(\n+ \"var __el = document.querySelector({sel}); if (__el) {{ Idiomorph.morph(__el, {html}, {{ morphStyle: 'innerHTML' }}); }}\",\n+ sel = js_string_literal(selector),\n+ ));\n+ self\n+ }\n+\n pub(crate) fn raw(mut self, js: &str) -> Self {\n if !js.is_empty() {\n self.snippets.push(js.to_string());\ndiff --git a/server/src/html/vote.rs b/server/src/html/vote.rs\nnew file mode 100644\nindex 0000000000000000000000000000000000000000..89ed621ad861214e147add2062224fc4137ff8ad\n--- /dev/null\n+++ b/server/src/html/vote.rs\n@@ -0,0 +1,306 @@\n+//! Pairwise vote UI — `/vote?parent=` with optional `left` / `right`.\n+\n+use axum::{\n+ extract::{Query, State},\n+ response::{Html, IntoResponse},\n+};\n+use maud::{html, Markup};\n+use serde::Deserialize;\n+\n+use crate::{\n+ form_template::template_json_compact,\n+ html::JsBuilder,\n+ pair::{children_of, resolve_pair, suggest_next_pair_in_pool},\n+ path_types::ItemId,\n+ reducer::{GlobalTree, GroupState, NodeState, VoteData},\n+ state::{parse_item_param, AppState},\n+ ui_action::UI_RPC_FIELD,\n+};\n+\n+use super::{breadcrumb_path, item_href, layout};\n+\n+#[derive(Debug, Deserialize)]\n+pub struct VoteQuery {\n+ pub parent: String,\n+ #[serde(default)]\n+ pub left: Option,\n+ #[serde(default)]\n+ pub right: Option,\n+}\n+\n+pub fn vote_href(parent: &ItemId) -> String {\n+ format!(\n+ \"/vote?parent={}\",\n+ urlencoding::encode(parent.as_str())\n+ )\n+}\n+\n+fn vote_compare_href(parent: &ItemId, left: &ItemId, right: &ItemId) -> String {\n+ format!(\n+ \"/vote?parent={}&left={}&right={}\",\n+ urlencoding::encode(parent.as_str()),\n+ urlencoding::encode(left.as_str()),\n+ urlencoding::encode(right.as_str()),\n+ )\n+}\n+\n+fn display_label(id: &ItemId) -> String {\n+ id.segments()\n+ .last()\n+ .map_or(\"item\".into(), |v| v.to_string())\n+}\n+\n+fn child_title(tree: &GlobalTree, id: &ItemId) -> String {\n+ tree.get(id)\n+ .and_then(|n| n.data.as_ref())\n+ .map(|d| d.title.clone())\n+ .unwrap_or_else(|| display_label(id))\n+}\n+\n+fn ratio_pct(ratio_left: i32, ratio_right: i32) -> f64 {\n+ let l = ratio_left.max(0) as f64;\n+ let r = ratio_right.max(0) as f64;\n+ let sum = l + r;\n+ if sum <= 0.0 {\n+ 50.0\n+ } else {\n+ (l / sum) * 100.0\n+ }\n+}\n+\n+fn ratios_for_page(v: &VoteData, page_left: &ItemId, page_right: &ItemId) -> (i32, i32) {\n+ match (v.a.as_str(), v.b.as_str()) {\n+ (a, b) if a == page_left.as_str() && b == page_right.as_str() => {\n+ (v.ratio_left, v.ratio_right)\n+ }\n+ (a, b) if a == page_right.as_str() && b == page_left.as_str() => {\n+ (v.ratio_right, v.ratio_left)\n+ }\n+ _ => (v.ratio_left, v.ratio_right),\n+ }\n+}\n+\n+fn edge_votes(group: &GroupState, left: &ItemId, right: &ItemId) -> Vec {\n+ group\n+ .recent_votes\n+ .iter()\n+ .filter(|v| {\n+ (v.a.as_str() == left.as_str() && v.b.as_str() == right.as_str())\n+ || (v.a.as_str() == right.as_str() && v.b.as_str() == left.as_str())\n+ })\n+ .cloned()\n+ .collect()\n+}\n+\n+fn vote_edge_history(tree: &GlobalTree, group: &GroupState, left: &ItemId, right: &ItemId) -> Markup {\n+ let mut votes = edge_votes(group, left, right);\n+ votes.sort_by(|a, b| b.ts.cmp(&a.ts));\n+ let legend_left = child_title(tree, left);\n+ let legend_right = child_title(tree, right);\n+ html! {\n+ @if votes.is_empty() {\n+ p class=\"muted vote-edge-empty\" { \"no votes on this pair yet\" }\n+ } @else {\n+ h3 class=\"vote-edge-history-title\" {\n+ \"votes on this pair\"\n+ span class=\"vote-edge-history-axis muted\" { \" · \" (legend_left) \" : \" (legend_right) }\n+ }\n+ ul class=\"vote-edge-history\" {\n+ @for v in &votes {\n+ @let (r_left, r_right) = ratios_for_page(v, left, right);\n+ @let pct = ratio_pct(r_left, r_right);\n+ li class=\"vote-edge-history-row\" {\n+ div class=\"vote-edge-meta\" {\n+ span class=\"vote-edge-ratio\" { (format!(\"{}:{}\", r_left, r_right)) }\n+ }\n+ div class=\"ratio-bar vote-edge-bar\" aria-hidden=\"true\" {\n+ div class=\"ratio-left\" style={(format!(\"width: {:.3}%;\", pct))} {}\n+ div class=\"ratio-right\" style={(format!(\"width: {:.3}%;\", 100.0 - pct))} {}\n+ }\n+ }\n+ }\n+ }\n+ }\n+ }\n+}\n+\n+fn vote_back_nav(parent: &ItemId) -> Markup {\n+ html! {\n+ div class=\"vote-compare-nav\" {\n+ a class=\"vote-compare-back muted\" href=(item_href(parent)) { \"← back to \" (display_label(parent)) }\n+ }\n+ }\n+}\n+\n+fn vote_compare_actions(parent: &ItemId, next: Option<&(ItemId, ItemId)>) -> Markup {\n+ let next_href = next.map(|(l, r)| vote_compare_href(parent, l, r));\n+ html! {\n+ div id=\"vote-compare-actions\" class=\"vote-compare-actions\" {\n+ button type=\"submit\" class=\"btn-primary\" data-testid=\"vote-post\" { \"post vote\" }\n+ @if let Some(href) = &next_href {\n+ a class=\"btn-secondary vote-compare-next\" data-testid=\"vote-next-pair\" href=(href) { \"next pair\" }\n+ } @else {\n+ span class=\"btn-secondary vote-compare-next is-disabled\" { \"no next pair\" }\n+ }\n+ }\n+ }\n+}\n+\n+/// After recording a vote on the compare page: refresh edge history and next-pair link.\n+pub(crate) fn vote_recorded_morph(\n+ tree: &GlobalTree,\n+ parent: &ItemId,\n+ left: &ItemId,\n+ right: &ItemId,\n+) -> JsBuilder {\n+ let pool = children_of(tree, parent);\n+ let empty = NodeState::default();\n+ let group = tree\n+ .get(parent)\n+ .unwrap_or(&empty)\n+ .local_ranking\n+ .clone();\n+ let edge_history = vote_edge_history(tree, &group, left, right);\n+ let next_pair = suggest_next(&group, left, right, &pool);\n+ let actions = vote_compare_actions(parent, next_pair.as_ref());\n+ JsBuilder::new()\n+ .morph_inner_selector(\"#vote-edge-history-region\", edge_history)\n+ .morph_selector(\"#vote-compare-actions\", actions)\n+}\n+\n+fn vote_compare_item_card(tree: &GlobalTree, item: &ItemId, side_class: &str) -> Markup {\n+ let href = item_href(item);\n+ let title = child_title(tree, item);\n+ html! {\n+ div class=(format!(\"vote-compare-side {side_class}\")) {\n+ a class=(format!(\"vote-compare-item {side_class}\")) href=(href) {\n+ @if let Some(row) = crate::render::reddit::child_row_markup(tree, item, &href) {\n+ (row)\n+ } @else {\n+ strong { (title) }\n+ }\n+ }\n+ @if let Some(node) = tree.get(item) {\n+ @if crate::render::reddit::is_reddit_post(item) {\n+ @if let Some(data) = &node.data {\n+ @if let Some(src) = data.image_url.as_ref().or(data.thumb_url.as_ref()) {\n+ figure class=\"vote-compare-figure\" {\n+ img class=\"vote-compare-image\" src=(src) alt=\"\" loading=\"lazy\";\n+ }\n+ }\n+ @if let Some(author) = &data.author {\n+ p class=\"muted small\" { \"by \" (author) }\n+ }\n+ }\n+ } @else if let Some(data) = &node.data {\n+ @if let Some(body) = &data.body_html {\n+ div class=\"vote-compare-item-body\" {\n+ (maud::PreEscaped(body))\n+ }\n+ }\n+ }\n+ }\n+ }\n+ }\n+}\n+\n+\n+fn suggest_next(group: &GroupState, left: &ItemId, right: &ItemId, pool: &[ItemId]) -> Option<(ItemId, ItemId)> {\n+ suggest_next_pair_in_pool(group, pool, Some((left, right)))\n+}\n+\n+pub async fn vote_page(\n+ State(state): State,\n+ Query(q): Query,\n+) -> impl IntoResponse {\n+ let parent = parse_item_param(&q.parent);\n+ let left_param = q.left.as_deref().map(parse_item_param);\n+ let right_param = q.right.as_deref().map(parse_item_param);\n+\n+ let tree = state.tree.read().await;\n+ let empty = NodeState::default();\n+ let parent_node = tree.get(&parent).unwrap_or(&empty);\n+\n+ let (left, right) = match resolve_pair(\n+ &tree,\n+ &parent,\n+ left_param.as_ref(),\n+ right_param.as_ref(),\n+ ) {\n+ Ok(p) => p,\n+ Err(e) => {\n+ let (msg, status) = e.status_message();\n+ return (status, msg).into_response();\n+ }\n+ };\n+\n+ let pool = children_of(&tree, &parent);\n+ let group = &parent_node.local_ranking;\n+ let next_pair = suggest_next(group, &left, &right, &pool);\n+ let edge_history = vote_edge_history(&tree, group, &left, &right);\n+\n+ let rpc_json = template_json_compact(&serde_json::json!({\n+ \"action\": \"record_vote\",\n+ \"a\": left.as_str(),\n+ \"b\": right.as_str(),\n+ \"ratio_left\": {\"$form:i32\": \"ratio_left\"},\n+ \"ratio_right\": {\"$form:i32\": \"ratio_right\"},\n+ \"scope\": parent.as_str(),\n+ \"vote_compare\": true,\n+ }))\n+ .expect(\"vote rpc json\");\n+\n+ let title = format!(\n+ \"vote — {} vs {}\",\n+ child_title(&tree, &left),\n+ child_title(&tree, &right)\n+ );\n+\n+ let body = html! {\n+ section class=\"vote-compare-shell\" {\n+ h1 { \"compare\" }\n+ (breadcrumb_path(&parent))\n+ p class=\"muted vote-compare-scope\" {\n+ \"ranking children of \"\n+ a href=(item_href(&parent)) { (child_title(&tree, &parent)) }\n+ }\n+ div class=\"vote-compare-pair\" {\n+ (vote_compare_item_card(&tree, &left, \"vote-compare-left\"))\n+ span class=\"vote-compare-vs\" { \"vs\" }\n+ (vote_compare_item_card(&tree, &right, \"vote-compare-right\"))\n+ }\n+ (vote_back_nav(&parent))\n+ div id=\"vote-edge-history-region\" {\n+ (edge_history)\n+ }\n+ form id=\"vote-compare-form\" method=\"POST\" action=\"/ui\" {\n+ input type=\"hidden\" name=(UI_RPC_FIELD) value=(rpc_json);\n+ input type=\"hidden\" name=\"ratio_left\" id=\"vote-ratio-left\" value=\"50\";\n+ input type=\"hidden\" name=\"ratio_right\" id=\"vote-ratio-right\" value=\"50\";\n+ label class=\"vote-compare-slider-label\" {\n+ span id=\"vote-slider-left-label\" { (child_title(&tree, &left)) }\n+ input type=\"range\" id=\"vote-preference-slider\" min=\"0\" max=\"100\" value=\"50\"\n+ aria-valuemin=\"0\" aria-valuemax=\"100\";\n+ span id=\"vote-slider-right-label\" { (child_title(&tree, &right)) }\n+ }\n+ (vote_compare_actions(&parent, next_pair.as_ref()))\n+ }\n+ }\n+ };\n+\n+ drop(tree);\n+\n+ let path = format!(\"/vote?parent={}\", urlencoding::encode(parent.as_str()));\n+ state.views.increment(path.clone());\n+ let views = state.views.get_views(&path);\n+\n+ Html(\n+ layout(\n+ &title,\n+ body,\n+ views,\n+ )\n+ .into_string(),\n+ )\n+ .into_response()\n+}\ndiff --git a/server/src/pair.rs b/server/src/pair.rs\nnew file mode 100644\nindex 0000000000000000000000000000000000000000..606ffa51038a57ffacf335aa48bdb1185f8483fb\n--- /dev/null\n+++ b/server/src/pair.rs\n@@ -0,0 +1,340 @@\n+//! Pick two children of a parent scope for pairwise voting.\n+//!\n+//! Pair selection prefers **bridge** votes — comparisons between items in\n+//! different connected components of the voted-pairs graph — so the pool\n+//! merges into one ranking group before refining within it.\n+\n+use rand::seq::SliceRandom;\n+use std::collections::{HashMap, HashSet};\n+\n+use crate::{\n+ path_types::ItemId,\n+ ranking::connected_components_from_voted_pairs,\n+ reducer::{GlobalTree, GroupState},\n+};\n+\n+fn pairs_match(a: &ItemId, b: &ItemId, x: &ItemId, y: &ItemId) -> bool {\n+ (a == x && b == y) || (a == y && b == x)\n+}\n+\n+fn pair_is_voted(group: &GroupState, a: &ItemId, b: &ItemId) -> bool {\n+ let Some(&ai) = group.item_to_idx.get(a) else {\n+ return false;\n+ };\n+ let Some(&bi) = group.item_to_idx.get(b) else {\n+ return false;\n+ };\n+ let (i, j) = if ai < bi { (ai, bi) } else { (bi, ai) };\n+ group.voted_pairs.contains(&(i, j))\n+}\n+\n+/// Component id per pool item: voted-pairs graph components plus one id per\n+/// never-voted child.\n+fn component_ids(group: &GroupState, pool: &[ItemId]) -> HashMap {\n+ let n = group.idx_to_item.len();\n+ let (comps, isolates) =\n+ connected_components_from_voted_pairs(n, group.voted_pairs.iter().copied());\n+\n+ let mut out: HashMap = HashMap::new();\n+ for (comp_idx, comp) in comps.iter().enumerate() {\n+ for &idx in comp {\n+ if idx < n {\n+ out.insert(group.idx_to_item[idx].clone(), comp_idx);\n+ }\n+ }\n+ }\n+ let mut next = comps.len();\n+ for &idx in &isolates {\n+ if idx < n {\n+ out.insert(group.idx_to_item[idx].clone(), next);\n+ next += 1;\n+ }\n+ }\n+ for item in pool {\n+ out.entry(item.clone()).or_insert_with(|| {\n+ let id = next;\n+ next += 1;\n+ id\n+ });\n+ }\n+ out\n+}\n+\n+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]\n+enum PairPriority {\n+ /// Unvoted edge between two components — grows the ranking group.\n+ BridgeUnvoted = 0,\n+ /// Unvoted edge inside one component — refines order.\n+ WithinUnvoted = 1,\n+ /// Re-vote across components (rare once merged).\n+ BridgeVoted = 2,\n+ /// Re-vote within a component.\n+ WithinVoted = 3,\n+}\n+\n+fn pair_priority(\n+ group: &GroupState,\n+ components: &HashMap,\n+ a: &ItemId,\n+ b: &ItemId,\n+) -> PairPriority {\n+ let voted = pair_is_voted(group, a, b);\n+ let bridge = components.get(a) != components.get(b);\n+ match (bridge, voted) {\n+ (true, false) => PairPriority::BridgeUnvoted,\n+ (false, false) => PairPriority::WithinUnvoted,\n+ (true, true) => PairPriority::BridgeVoted,\n+ (false, true) => PairPriority::WithinVoted,\n+ }\n+}\n+\n+/// All unordered pairs from `pool`, optionally skipping `exclude`.\n+fn candidate_pairs(\n+ pool: &[ItemId],\n+ exclude: Option<(&ItemId, &ItemId)>,\n+) -> Vec<(ItemId, ItemId)> {\n+ let mut out = Vec::new();\n+ for i in 0..pool.len() {\n+ for j in (i + 1)..pool.len() {\n+ let a = &pool[i];\n+ let b = &pool[j];\n+ if a == b {\n+ continue;\n+ }\n+ if exclude.is_some_and(|(x, y)| pairs_match(a, b, x, y)) {\n+ continue;\n+ }\n+ out.push((a.clone(), b.clone()));\n+ }\n+ }\n+ out\n+}\n+\n+/// Pick the next pair to vote on within `pool`.\n+///\n+/// 1. Prefer unvoted **bridge** pairs (connect separate ranking components).\n+/// 2. Then unvoted within-component pairs (refinement).\n+/// 3. Then already-voted pairs (re-compare).\n+pub fn suggest_next_pair_in_pool(\n+ group: &GroupState,\n+ pool: &[ItemId],\n+ exclude: Option<(&ItemId, &ItemId)>,\n+) -> Option<(ItemId, ItemId)> {\n+ let candidates = candidate_pairs(pool, exclude);\n+ if candidates.is_empty() {\n+ return None;\n+ }\n+ let components = component_ids(group, pool);\n+ let best = candidates\n+ .iter()\n+ .map(|(a, b)| (pair_priority(group, &components, a, b), (a, b)))\n+ .min_by_key(|(p, _)| *p)?\n+ .0;\n+ let best_pairs: Vec<(ItemId, ItemId)> = candidates\n+ .into_iter()\n+ .filter(|(a, b)| pair_priority(group, &components, a, b) == best)\n+ .collect();\n+ best_pairs.choose(&mut rand::thread_rng()).cloned()\n+}\n+\n+/// Random distinct pair from `children` (legacy pair.rs behavior).\n+pub fn random_pair(children: &[ItemId]) -> Option<(ItemId, ItemId)> {\n+ if children.len() < 2 {\n+ return None;\n+ }\n+ let left = children.choose(&mut rand::thread_rng())?;\n+ let mut right = children.choose(&mut rand::thread_rng())?;\n+ let mut guard = 0;\n+ while left == right && guard < 32 {\n+ right = children.choose(&mut rand::thread_rng())?;\n+ guard += 1;\n+ }\n+ if left == right {\n+ return None;\n+ }\n+ Some((left.clone(), right.clone()))\n+}\n+\n+/// Sorted children of `parent` from the global tree.\n+pub fn children_of(tree: &GlobalTree, parent: &ItemId) -> Vec {\n+ let Some(node) = tree.get(parent) else {\n+ return Vec::new();\n+ };\n+ let mut children: Vec = node.children.iter().cloned().collect();\n+ children.sort_by(|a, b| a.as_str().cmp(b.as_str()));\n+ children\n+}\n+\n+/// Resolve a pair to compare under `parent`.\n+pub fn resolve_pair(\n+ tree: &GlobalTree,\n+ parent: &ItemId,\n+ left: Option<&ItemId>,\n+ right: Option<&ItemId>,\n+) -> Result<(ItemId, ItemId), PairError> {\n+ let children = children_of(tree, parent);\n+ if children.len() < 2 {\n+ return Err(PairError::TooFewChildren);\n+ }\n+ let child_set: HashSet<_> = children.iter().collect();\n+\n+ match (left, right) {\n+ (Some(l), Some(r)) => {\n+ if l == r {\n+ return Err(PairError::SameItem);\n+ }\n+ if !child_set.contains(l) || !child_set.contains(r) {\n+ return Err(PairError::NotChild);\n+ }\n+ Ok((l.clone(), r.clone()))\n+ }\n+ (None, None) => {\n+ let group = tree\n+ .get(parent)\n+ .map(|n| &n.local_ranking)\n+ .cloned()\n+ .unwrap_or_default();\n+ suggest_next_pair_in_pool(&group, &children, None).ok_or(PairError::NoPair)\n+ }\n+ _ => Err(PairError::IncompletePair),\n+ }\n+}\n+\n+#[derive(Debug, Clone, PartialEq, Eq)]\n+pub enum PairError {\n+ TooFewChildren,\n+ SameItem,\n+ NotChild,\n+ IncompletePair,\n+ NoPair,\n+}\n+\n+impl PairError {\n+ pub fn status_message(&self) -> (&'static str, axum::http::StatusCode) {\n+ match self {\n+ Self::TooFewChildren => (\n+ \"parent needs at least 2 children to vote\",\n+ axum::http::StatusCode::BAD_REQUEST,\n+ ),\n+ Self::SameItem => (\n+ \"left and right must differ\",\n+ axum::http::StatusCode::BAD_REQUEST,\n+ ),\n+ Self::NotChild => (\n+ \"left and right must be children of parent\",\n+ axum::http::StatusCode::BAD_REQUEST,\n+ ),\n+ Self::IncompletePair => (\n+ \"provide both left and right, or neither\",\n+ axum::http::StatusCode::BAD_REQUEST,\n+ ),\n+ Self::NoPair => (\n+ \"no pair available\",\n+ axum::http::StatusCode::BAD_REQUEST,\n+ ),\n+ }\n+ }\n+}\n+\n+#[cfg(test)]\n+mod tests {\n+ use super::*;\n+ use crate::reducer::{GlobalTree, VoteData};\n+\n+ fn seed_children(parent: &ItemId, ids: &[&str]) -> GlobalTree {\n+ let mut tree = GlobalTree::new();\n+ tree.ensure_path(parent);\n+ for id in ids {\n+ let child = ItemId::parse(id).unwrap();\n+ tree.ensure_path(&child);\n+ if let Some(p) = tree.nodes.get_mut(parent) {\n+ p.children.insert(child);\n+ }\n+ }\n+ tree\n+ }\n+\n+ fn pair_set(pair: &(ItemId, ItemId)) -> HashSet<&str> {\n+ [pair.0.as_str(), pair.1.as_str()].into_iter().collect()\n+ }\n+\n+ #[test]\n+ fn suggest_prefers_unvoted_pair() {\n+ let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+ let mut tree = seed_children(\n+ &parent,\n+ &[\n+ \"reddit.com/r/rust/a\",\n+ \"reddit.com/r/rust/b\",\n+ \"reddit.com/r/rust/c\",\n+ ],\n+ );\n+ let vote =\n+ VoteData::from_recorded(1, \"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\", 2, 1).unwrap();\n+ tree.apply_vote(&parent, vote);\n+ let group = tree.get(&parent).unwrap().local_ranking.clone();\n+ let pool = children_of(&tree, &parent);\n+ let (l, r) = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n+ let voted_ab = (l.as_str() == \"reddit.com/r/rust/a\" && r.as_str() == \"reddit.com/r/rust/b\")\n+ || (l.as_str() == \"reddit.com/r/rust/b\" && r.as_str() == \"reddit.com/r/rust/a\");\n+ assert!(!voted_ab);\n+ }\n+\n+ #[test]\n+ fn suggest_bridges_separate_components() {\n+ let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+ let mut tree = seed_children(\n+ &parent,\n+ &[\n+ \"reddit.com/r/rust/a\",\n+ \"reddit.com/r/rust/b\",\n+ \"reddit.com/r/rust/c\",\n+ \"reddit.com/r/rust/d\",\n+ ],\n+ );\n+ let ab = VoteData::from_recorded(1, \"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\", 2, 1).unwrap();\n+ let cd = VoteData::from_recorded(2, \"reddit.com/r/rust/c\", \"reddit.com/r/rust/d\", 2, 1).unwrap();\n+ tree.apply_vote(&parent, ab);\n+ tree.apply_vote(&parent, cd);\n+ let group = tree.get(&parent).unwrap().local_ranking.clone();\n+ let pool = children_of(&tree, &parent);\n+ let pair = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n+ let chosen = pair_set(&pair);\n+ let from_ab = chosen.contains(\"reddit.com/r/rust/a\") || chosen.contains(\"reddit.com/r/rust/b\");\n+ let from_cd = chosen.contains(\"reddit.com/r/rust/c\") || chosen.contains(\"reddit.com/r/rust/d\");\n+ assert!(from_ab && from_cd, \"expected bridge pair, got {:?}\", chosen);\n+ }\n+\n+ #[test]\n+ fn suggest_connects_isolate_to_existing_component() {\n+ let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+ let mut tree = seed_children(\n+ &parent,\n+ &[\n+ \"reddit.com/r/rust/a\",\n+ \"reddit.com/r/rust/b\",\n+ \"reddit.com/r/rust/c\",\n+ ],\n+ );\n+ let ab = VoteData::from_recorded(1, \"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\", 2, 1).unwrap();\n+ tree.apply_vote(&parent, ab);\n+ let group = tree.get(&parent).unwrap().local_ranking.clone();\n+ let pool = children_of(&tree, &parent);\n+ let pair = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n+ let chosen = pair_set(&pair);\n+ assert!(chosen.contains(\"reddit.com/r/rust/c\"));\n+ assert!(chosen.contains(\"reddit.com/r/rust/a\") || chosen.contains(\"reddit.com/r/rust/b\"));\n+ }\n+\n+ #[test]\n+ fn resolve_pair_picks_from_pool() {\n+ let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+ let tree = seed_children(&parent, &[\"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\"]);\n+ let pair = resolve_pair(&tree, &parent, None, None).unwrap();\n+ let pool: HashSet<_> = [\"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\"]\n+ .into_iter()\n+ .collect();\n+ assert!(pool.contains(pair.0.as_str()));\n+ assert!(pool.contains(pair.1.as_str()));\n+ }\n+}\ndiff --git a/server/src/path_types.rs b/server/src/path_types.rs\nindex 12dce9888f5cd4e1a0974d12d6468368d0f775b9..a0d1a028b8bd3c5d1c714dea3ec597d1ac39e1bc 100644\n--- a/server/src/path_types.rs\n+++ b/server/src/path_types.rs\n@@ -40,6 +40,22 @@ impl ItemId {\n Self::canonicalize(raw_url).map(Self)\n }\n \n+ /// Normalize strings from forms, events, and Reddit imports into the same\n+ /// stored id shape (e.g. drop post title slug after comment id).\n+ pub fn from_storage(s: &str) -> Option {\n+ let t = s.trim();\n+ if t.is_empty() {\n+ return None;\n+ }\n+ if t.contains(\"://\") || t.starts_with(\"r/\") {\n+ return Self::from_url(t).or_else(|| Self::parse(t));\n+ }\n+ if t.starts_with(\"reddit.com/\") && t.contains(\"/comments/\") {\n+ return Self::from_url(t).or_else(|| Self::parse(t));\n+ }\n+ Self::parse(t).or_else(|| Self::from_url(t))\n+ }\n+\n /// Map legacy scope keys (`\"\"`, `\"rust\"`) to fractal parent nodes.\n pub fn from_legacy_scope(raw: &str) -> Self {\n let s = raw.trim();\n@@ -324,6 +340,12 @@ mod tests {\n assert_eq!(id.as_str(), \"reddit.com/r/amitheasshole\");\n }\n \n+ #[test]\n+ fn from_storage_strips_post_title_slug() {\n+ let id = ItemId::from_storage(\"reddit.com/r/rust/comments/aaa/announcing_rust_199\").unwrap();\n+ assert_eq!(id.as_str(), \"reddit.com/r/rust/comments/aaa\");\n+ }\n+\n #[test]\n fn from_browse_uri_strips_prefix() {\n let id = ItemId::from_browse_uri(\"/~/https://reddit.com/r/rust\").unwrap();\ndiff --git a/server/src/reddit.rs b/server/src/reddit.rs\nindex 1168ec2afc77c092514eec91b513bac301cbe225..626454e5a2f638734193b5190a2beea286af85b6 100644\n--- a/server/src/reddit.rs\n+++ b/server/src/reddit.rs\n@@ -567,7 +567,7 @@ fn parse_children(_parent: &ItemId, payload: &Value) -> Vec<(ItemId, Value)> {\n _ => continue,\n };\n let path = format!(\"reddit.com{}\", permalink.trim_end_matches('/'));\n- if let Some(id) = ItemId::parse(&path) {\n+ if let Some(id) = ItemId::from_storage(&path) {\n out.push((id, child.clone()));\n }\n }\ndiff --git a/server/src/reducer.rs b/server/src/reducer.rs\nindex 336e78b77d3ab59361b89af5c9868e13da4ac962..fc23f41137d7df33997afe19c533505c250cc305 100644\n--- a/server/src/reducer.rs\n+++ b/server/src/reducer.rs\n@@ -28,8 +28,8 @@ impl VoteData {\n ratio_left: i32,\n ratio_right: i32,\n ) -> Option {\n- let a = ItemId::parse(a)?;\n- let b = ItemId::parse(b)?;\n+ let a = ItemId::from_storage(a)?;\n+ let b = ItemId::from_storage(b)?;\n if a == b {\n return None;\n }\n@@ -85,8 +85,8 @@ impl GroupState {\n }\n \n pub fn apply_vote(&mut self, mut vote: VoteData) {\n- vote.a = ItemId::parse(vote.a.as_str()).unwrap_or_else(|| vote.a.clone());\n- vote.b = ItemId::parse(vote.b.as_str()).unwrap_or_else(|| vote.b.clone());\n+ vote.a = ItemId::from_storage(vote.a.as_str()).unwrap_or(vote.a.clone());\n+ vote.b = ItemId::from_storage(vote.b.as_str()).unwrap_or(vote.b.clone());\n if vote.ratio_left < 0 {\n vote.ratio_left = 0;\n }\ndiff --git a/server/src/state.rs b/server/src/state.rs\nindex d238701208a1c708b94a778a6a2e1891a678ecbc..4c3008e73cc74d8483a2064a0a280e73d82a01ec 100644\n--- a/server/src/state.rs\n+++ b/server/src/state.rs\n@@ -18,7 +18,7 @@ pub fn parse_item_param(raw: &str) -> ItemId {\n if s.is_empty() {\n return ItemId::root();\n }\n- ItemId::from_url(s).or_else(|| ItemId::parse(s)).unwrap_or_else(|| ItemId::opaque(s))\n+ ItemId::from_storage(s).unwrap_or_else(|| ItemId::opaque(s))\n }\n \n /// Legacy: normalize raw ranking subject into a scope key for old event replay.\ndiff --git a/server/src/ui_action.rs b/server/src/ui_action.rs\nindex 53581e1362bfcc5dfb4ae3069c41ea6f7be41437..237411a689fb10ad1b7022ea66aee1969c7507ec 100644\n--- a/server/src/ui_action.rs\n+++ b/server/src/ui_action.rs\n@@ -31,9 +31,9 @@ pub enum HtmlUiAction {\n /// Parent node [`ItemId`] string; empty = tree root.\n #[serde(default)]\n scope: String,\n- /// After vote, navigate here (vote compare page).\n+ /// Posted from `/vote` compare UI — morph edge history in place.\n #[serde(default)]\n- next: String,\n+ vote_compare: bool,\n },\n /// Parse pasted Reddit URL/path; redirect to subreddit ranking on success.\n ParseQuery {\n@@ -98,7 +98,7 @@ mod tests {\n ratio_left: 60,\n ratio_right: 40,\n scope: \"parent\".into(),\n- next: String::new(),\n+ vote_compare: false,\n }\n );\n }\n@@ -129,7 +129,7 @@ mod tests {\n ratio_left: 2,\n ratio_right: 1,\n scope: \"amitheasshole\".into(),\n- next: String::new(),\n+ vote_compare: false,\n }\n );\n }\n@@ -156,7 +156,7 @@ mod tests {\n ratio_left: 2,\n ratio_right: 1,\n scope: String::new(),\n- next: String::new(),\n+ vote_compare: false,\n }\n );\n }\ndiff --git a/server/static/sorter.css b/server/static/sorter.css\nindex 3c2cec5cb5094013387147c621d75bd341bc06cc..b95718ce463b200a5667d3014dac2119836a0bef 100644\n--- a/server/static/sorter.css\n+++ b/server/static/sorter.css\n@@ -289,11 +289,27 @@ h1 {\n }\n \n .vote-compare-nav {\n+ margin: 1rem 0 0.5rem;\n+}\n+\n+.vote-compare-actions {\n display: flex;\n- justify-content: space-between;\n+ flex-wrap: wrap;\n align-items: center;\n- gap: 1rem;\n- margin: 1rem 0;\n+ gap: 0.75rem;\n+ margin-top: 0.5rem;\n+}\n+\n+.vote-compare-actions .btn-secondary {\n+ margin-top: 0;\n+ display: inline-block;\n+ text-decoration: none;\n+ line-height: 1.4;\n+}\n+\n+.vote-compare-actions .vote-compare-next.is-disabled {\n+ opacity: 0.6;\n+ cursor: default;\n }\n \n .vote-compare-next {\ndiff --git a/server/static/sorter_ui.js b/server/static/sorter_ui.js\nindex c8d7c3ef2413399ced7898a7edb3e7a2c8e16163..ab15d27f508cc6f5fbca9d8926fd0ca26d64857b 100644\n--- a/server/static/sorter_ui.js\n+++ b/server/static/sorter_ui.js\n@@ -104,11 +104,10 @@\n if (f.getAttribute('data-navigate') === 'full') return;\n e.preventDefault();\n await postUiForm(f);\n- if (f.id === 'vote-form' || f.id === 'vote-compare-form') {\n+ if (f.id === 'vote-form') {\n f.reset();\n- var slider = f.querySelector('#vote-preference-slider');\n- if (slider) slider.value = '50';\n- initVoteSlider();\n+ var firstField = f.querySelector('input[type=\"text\"]');\n+ if (firstField) firstField.focus();\n }\n });\n }\ndiff --git a/server/tests/integration_ui.rs b/server/tests/integration_ui.rs\nindex df7d9ab357531c5146d0b326c149fdaa6b531a4a..56d2db313b313ffce07eff38a8ccdaa2fbb9498f 100644\n--- a/server/tests/integration_ui.rs\n+++ b/server/tests/integration_ui.rs\n@@ -25,6 +25,53 @@ async fn start_test_server() -> (SocketAddr, TempDir) {\n (addr, tmp)\n }\n \n+#[tokio::test]\n+async fn post_ui_vote_compare_morphs_edge_history() {\n+ let (addr, _tmp) = start_test_server().await;\n+ let parent = \"reddit.com/r/rust\";\n+ let a = \"reddit.com/r/rust/comments/aaa/announcing_rust_199\";\n+ let b = \"reddit.com/r/rust/comments/bbb/what_are_you_working_on\";\n+\n+ let rpc = serde_json::json!({\n+ \"action\": \"record_vote\",\n+ \"a\": a,\n+ \"b\": b,\n+ \"ratio_left\": {\"$form:i32\": \"ratio_left\"},\n+ \"ratio_right\": {\"$form:i32\": \"ratio_right\"},\n+ \"scope\": parent,\n+ \"vote_compare\": true,\n+ })\n+ .to_string();\n+ let mut form = HashMap::new();\n+ form.insert(UI_RPC_FIELD.to_string(), rpc);\n+ form.insert(\"ratio_left\".into(), \"70\".into());\n+ form.insert(\"ratio_right\".into(), \"30\".into());\n+\n+ let client = reqwest::Client::new();\n+ let body = client\n+ .post(format!(\"http://{addr}/ui\"))\n+ .form(&form)\n+ .send()\n+ .await\n+ .unwrap()\n+ .text()\n+ .await\n+ .unwrap();\n+\n+ assert!(\n+ body.contains(\"vote-edge-history\"),\n+ \"expected edge history morph, got: {body}\"\n+ );\n+ assert!(\n+ body.contains(\"70:30\"),\n+ \"expected recorded ratio in morph, got: {body}\"\n+ );\n+ assert!(\n+ !body.contains(\"no votes on this pair yet\"),\n+ \"should not show empty edge history after vote, got: {body}\"\n+ );\n+}\n+\n #[tokio::test]\n async fn post_ui_record_vote_morphs_ranking_and_persists() {\n let (addr, tmp) = start_test_server().await;\ndiff --git a/test/reddit_import.clj b/test/reddit_import.clj\nindex 45a2a19f20799d77e84d8aa64735ab5e7e45f97c..b476488526252c13fd73bdda76e5201678e4a714 100644\n--- a/test/reddit_import.clj\n+++ b/test/reddit_import.clj\n@@ -2,9 +2,8 @@\n (:require [babashka.process :as process]\n [clojure.java.io :as io]\n [clojure.string :as str]\n- [clojure.test :refer [deftest is testing]])\n- (:import [com.sun.net.httpserver HttpServer HttpHandler HttpExchange]\n- [java.net InetSocketAddress]))\n+ [clojure.test :refer [deftest is testing]]\n+ [test.support.mock-reddit :as mock-reddit]))\n \n (defn- repo-root []\n (.getCanonicalPath (io/file (System/getProperty \"user.dir\"))))\n@@ -13,29 +12,6 @@\n (with-open [s (java.net.ServerSocket. 0)]\n (.getLocalPort s)))\n \n-(defn- start-mock-reddit [port fixtures-dir]\n- (let [about (.getBytes (slurp (io/file fixtures-dir \"r_rust_about.json\")) \"UTF-8\")\n- listing (.getBytes (slurp (io/file fixtures-dir \"r_rust_listing.json\")) \"UTF-8\")\n- server (HttpServer/create (InetSocketAddress. \"127.0.0.1\" port) 0)\n- handler\n- (proxy [HttpHandler] []\n- (handle [^HttpExchange exchange]\n- ;; Route by path: `/r//about.json` is the subreddit entity,\n- ;; `/r/.json` is the children listing.\n- (let [path (.getPath (.getRequestURI exchange))\n- body (if (str/includes? path \"/about\")\n- about\n- listing)]\n- (.sendResponseHeaders exchange 200 (alength body))\n- (let [out (.getResponseBody exchange)]\n- (.write out body)\n- (.close out)))))]\n- (.createContext server \"/\" handler)\n- (.setExecutor server nil)\n- (.start server)\n- (fn stop []\n- (.stop server 0))))\n-\n (defn- wait-health [base-url ms]\n (let [deadline (+ (System/currentTimeMillis) ms)\n url (str base-url \"/healthz\")]\n@@ -100,7 +76,7 @@\n (deftest reddit-fetch-via-mock-api\n (testing \"Fetch more queues import; event log stores full payload; page shows title\"\n (let [root (repo-root)\n- fixtures (str root \"/test/fixtures/reddit\")\n+ fixtures (mock-reddit/fixtures-dir root)\n data-dir (.getAbsolutePath\n (doto (io/file (System/getProperty \"java.io.tmpdir\")\n (str \"sorter2-reddit-\" (System/currentTimeMillis)))\n@@ -110,7 +86,7 @@\n reddit-base (str \"http://127.0.0.1:\" reddit-port)\n app-base (str \"http://127.0.0.1:\" app-port)\n bin (str root \"/target/release/sorter2-server\")\n- stop-mock (start-mock-reddit reddit-port fixtures)]\n+ stop-mock (mock-reddit/start-mock-reddit reddit-port fixtures)]\n (try\n (is (zero? (:exit (process/shell {:dir root}\n \"cargo\" \"build\" \"--release\" \"--package\" \"sorter2-server\")))\ndiff --git a/test/support/mock_reddit.clj b/test/support/mock_reddit.clj\nnew file mode 100644\nindex 0000000000000000000000000000000000000000..5efa92db3e1f79b8f423a2f1adcbda959123c1ad\n--- /dev/null\n+++ b/test/support/mock_reddit.clj\n@@ -0,0 +1,35 @@\n+(ns test.support.mock-reddit\n+ \"In-process HTTP stub for Reddit API fixtures (`test/fixtures/reddit/`).\"\n+ (:require [clojure.java.io :as io]\n+ [clojure.string :as str])\n+ (:import [com.sun.net.httpserver HttpServer HttpHandler HttpExchange]\n+ [java.net InetSocketAddress]))\n+\n+(defn fixtures-dir\n+ ([] (fixtures-dir (System/getProperty \"user.dir\")))\n+ ([root] (str root \"/test/fixtures/reddit\")))\n+\n+(defn start-mock-reddit\n+ \"Start a mock Reddit API on `port`. Returns a zero-arg `stop` function.\"\n+ ([port] (start-mock-reddit port (fixtures-dir)))\n+ ([port dir]\n+ (let [about (.getBytes (slurp (io/file dir \"r_rust_about.json\")) \"UTF-8\")\n+ listing (.getBytes (slurp (io/file dir \"r_rust_listing.json\")) \"UTF-8\")\n+ server (HttpServer/create (InetSocketAddress. \"127.0.0.1\" port) 0)\n+ handler\n+ (proxy [HttpHandler] []\n+ (handle [^HttpExchange exchange]\n+ ;; `/r//about.json` → subreddit entity; `/r/.json` → listing.\n+ (let [path (.getPath (.getRequestURI exchange))\n+ body (if (str/includes? path \"/about\")\n+ about\n+ listing)]\n+ (.sendResponseHeaders exchange 200 (alength body))\n+ (let [out (.getResponseBody exchange)]\n+ (.write out body)\n+ (.close out)))))]\n+ (.createContext server \"/\" handler)\n+ (.setExecutor server nil)\n+ (.start server)\n+ (fn stop []\n+ (.stop server 0)))))\ndiff --git a/test/vote_compare.clj b/test/vote_compare.clj\nnew file mode 100644\nindex 0000000000000000000000000000000000000000..fbc00281e466a1ba0833193c7b96fa30aeb45a5c\n--- /dev/null\n+++ b/test/vote_compare.clj\n@@ -0,0 +1,101 @@\n+(ns test.vote-compare\n+ (:require [babashka.process :as process]\n+ [clojure.java.io :as io]\n+ [clojure.string :as str]\n+ [clojure.test :refer [deftest is testing]]\n+ [com.blockether.spel.core :as core]\n+ [com.blockether.spel.locator :as loc]\n+ [com.blockether.spel.page :as page]\n+ [test.support.mock-reddit :as mock-reddit])\n+ (:import [java.net URLEncoder]))\n+\n+(defn- repo-root []\n+ (.getCanonicalPath (io/file (System/getProperty \"user.dir\"))))\n+\n+(defn- pick-port []\n+ (with-open [s (java.net.ServerSocket. 0)]\n+ (.getLocalPort s)))\n+\n+(defn- wait-health [base-url ms]\n+ (let [deadline (+ (System/currentTimeMillis) ms)\n+ url (str base-url \"/healthz\")]\n+ (loop []\n+ (let [resp (try\n+ (process/shell {:out :string :err :string}\n+ \"curl\" \"-sf\" url)\n+ (catch Exception _ nil))]\n+ (if (and resp (zero? (:exit resp)) (= \"ok\" (str/trim (:out resp \"\"))))\n+ true\n+ (if (< (System/currentTimeMillis) deadline)\n+ (do (Thread/sleep 200) (recur))\n+ false))))))\n+\n+(defn- curl-fetch-children [base item]\n+ (process/shell {:out :string :err :string}\n+ \"curl\" \"-sfN\" \"--max-time\" \"20\"\n+ \"-X\" \"POST\" (str base \"/ui\")\n+ \"--data-urlencode\"\n+ (str \"__rpc__={\\\"action\\\":\\\"fetch_entity\\\",\\\"item\\\":\\\"\" item\n+ \"\\\",\\\"kind\\\":\\\"children\\\"}\")))\n+\n+(defn- vote-page-url [base parent]\n+ (str base \"/vote?parent=\"\n+ (URLEncoder/encode parent \"UTF-8\")))\n+\n+(deftest vote-compare-shows-recorded-vote-after-post\n+ (testing \"post vote on /vote morphs edge history (mock Reddit children seeded)\"\n+ (let [root (repo-root)\n+ fixtures (mock-reddit/fixtures-dir root)\n+ data-dir (.getAbsolutePath\n+ (doto (io/file (System/getProperty \"java.io.tmpdir\")\n+ (str \"sorter2-vote-\" (System/currentTimeMillis)))\n+ (.mkdirs)))\n+ reddit-port (pick-port)\n+ app-port (pick-port)\n+ reddit-base (str \"http://127.0.0.1:\" reddit-port)\n+ app-base (str \"http://127.0.0.1:\" app-port)\n+ bin (str root \"/target/release/sorter2-server\")\n+ stop-mock (mock-reddit/start-mock-reddit reddit-port fixtures)]\n+ (try\n+ (is (zero? (:exit (process/shell {:dir root}\n+ \"cargo\" \"build\" \"--release\" \"--package\" \"sorter2-server\")))\n+ \"release build succeeds\")\n+ (let [proc (process/process {:dir root\n+ :env (into (into {} (System/getenv))\n+ {\"SORTER2_SKIP_DOTENV\" \"1\"\n+ \"SORTER2_DATA_DIR\" data-dir\n+ \"SORTER2_EVENT_LOG\" (str data-dir \"/events.jsonl\")\n+ \"PORT\" (str app-port)\n+ \"REDDIT_API_BASE\" reddit-base\n+ \"REDDIT_OAUTH_BASE\" reddit-base\n+ \"REDDIT_CLIENT_ID\" \"\"\n+ \"REDDIT_CLIENT_SECRET\" \"\"\n+ \"REDDIT_APP_ID\" \"\"\n+ \"REDDIT_APP_SECRET\" \"\"})\n+ :out :string\n+ :err :string}\n+ bin)]\n+ (try\n+ (is (wait-health app-base 20000) \"app healthz\")\n+ (let [fetch (curl-fetch-children app-base \"reddit.com/r/rust\")]\n+ (is (zero? (:exit fetch)) \"fetch posts via mock Reddit\")\n+ (is (str/includes? (:out fetch) \"Idiomorph.morph\")))\n+ (core/with-testing-page [pg]\n+ (page/navigate pg (vote-page-url app-base \"reddit.com/r/rust\"))\n+ (page/wait-for-selector pg \"#vote-compare-form\")\n+ (let [before (loc/text-content (page/locator pg \"#vote-edge-history-region\"))]\n+ (is (str/includes? before \"no votes on this pair yet\")\n+ \"empty edge history before first vote\"))\n+ (loc/click (page/get-by-test-id pg \"vote-post\"))\n+ (page/wait-for-selector pg \".vote-edge-history-title\")\n+ (let [after (loc/text-content (page/locator pg \"#vote-edge-history-region\"))]\n+ (is (str/includes? after \"votes on this pair\")\n+ \"shows edge history title after vote\")\n+ (is (str/includes? after \"50:50\")\n+ \"shows submitted ratio after vote\")\n+ (is (not (str/includes? after \"no votes on this pair yet\"))\n+ \"does not revert to empty edge history\")))\n+ (finally\n+ (process/destroy proc))))\n+ (finally\n+ (stop-mock))))))\n","role":"user"}],"model":"~x-ai/grok-latest"}