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:
[00be3a29] invite system

Side A — unified diff (full patch):
diff --git a/bb.edn b/bb.edn
index 50be8232847e672b3f273a2fb25ddd1d12adb7e2..818f850765370d12d58f239e287764fc3649d78b 100644
--- a/bb.edn
+++ b/bb.edn
@@ -47,14 +47,16 @@
                                            "RUST_LOG"      "info"})})))}
 
   test
-  {:doc "Full test suite: integration + auth + grants"
+  {:doc "Full test suite: integration + auth + grants + invites"
    :requires ([test.integration :as integration]
               [test.auth :as auth]
-              [test.grants :as grants])
+              [test.grants :as grants]
+              [test.invites :as invites])
    :task (do
            (integration/integration)
            (auth/auth-test)
-           (grants/grants-test))}
+           (grants/grants-test)
+           (invites/invites-test))}
 
   perf
   {:doc "Performance test: concurrent HTTP requests to detect blocking I/O"
diff --git a/cli/src/main.rs b/cli/src/main.rs
index e5833b0b93d8e667b94c574ba2b0f8cb758ff3df..8eda9f485bd1f7392f1e34be27176c21e20354eb 100644
--- a/cli/src/main.rs
+++ b/cli/src/main.rs
@@ -105,6 +105,23 @@ enum ScopedCmd {
         #[arg(long)]
         json: bool,
     },
+
+    /// Mint a shareable invite link (24h TTL, in-memory until redeemed). Requires Manage on the room.
+    InviteLink {
+        /// Comma-separated: view, post, vote, add_item, manage
+        #[arg(long = "caps", value_delimiter = ',')]
+        caps: Vec<String>,
+        #[arg(long, default_value_t = 1)]
+        uses: usize,
+        #[arg(long)]
+        json: bool,
+    },
+
+    /// List principals granted access in this room (requires View or Manage)
+    Audit {
+        #[arg(long)]
+        json: bool,
+    },
 }
 
 #[derive(Subcommand, Debug)]
@@ -514,17 +531,35 @@ fn print_thread(resp: &ThreadDetailResponse) {
         .duration_since(std::time::UNIX_EPOCH)
         .unwrap_or_default()
         .as_millis() as i64;
-    if resp.total > resp.posts.len() {
-        let end = resp.offset + resp.posts.len();
-        eprintln!("# showing {}-{} of {} posts  (--offset N --limit N to paginate)", resp.offset, end.saturating_sub(1), resp.total);
+    if resp.total > resp.items.len() {
+        let end = resp.offset + resp.items.len();
+        eprintln!(
+            "# showing {}-{} of {} rows  (--offset N --limit N to paginate)",
+            resp.offset,
+            end.saturating_sub(1),
+            resp.total
+        );
     }
-    for (i, post) in resp.posts.iter().enumerate() {
-        let timeago = slug_types::timeago::timeago_compact(now_ms, post.ts);
-        let body = &post.body.trim();
-        println!("<post index=\"{}\" timeago=\"{}\">", post.index, timeago);
-        println!("{}", body);
-        println!("</post>");
-        if i + 1 < resp.posts.len() {
+    for (i, item) in resp.items.iter().enumerate() {
+        match item {
+            ThreadItem::Post {
+                index,
+                ts,
+                body,
+                ..
+            } => {
+                let timeago = slug_types::timeago::timeago_compact(now_ms, *ts);
+                let body = body.trim();
+                println!("<post index=\"{}\" timeago=\"{}\">", index, timeago);
+                println!("{}", body);
+                println!("</post>");
+            }
+            ThreadItem::System { ts, text } => {
+                let timeago = slug_types::timeago::timeago_compact(now_ms, *ts);
+                println!("<system timeago=\"{}\">{}</system>", timeago, text.trim());
+            }
+        }
+        if i + 1 < resp.items.len() {
             println!();
             println!();
         }
@@ -1036,6 +1071,95 @@ async fn run_scoped(base: &str, room: &str, sub: ScopedCmd) -> Result<()> {
                 }
             }
         },
+        ScopedCmd::InviteLink { caps, uses, json } => {
+            let caps: Vec<String> = caps
+                .into_iter()
+                .flat_map(|s| {
+                    s.split(',')
+                        .map(|p| p.trim().to_lowercase())
+                        .filter(|p| !p.is_empty())
+                        .collect::<Vec<_>>()
+                })
+                .collect();
+            if caps.is_empty() {
+                return Err(anyhow!("--caps is required (e.g. --caps view,post,vote)"));
+            }
+            let bearer = effective_bearer().ok_or_else(|| {
+                anyhow!(
+                    "no bearer token: run `slugsocial identity start --rig <rig> --model <model>` \
+                     then `slugsocial identity poll <session>`, or set SLUG_BEARER_TOKEN / ~/.config/slugsocial/token"
+                )
+            })?;
+            let batch = send_rpc(
+                &client,
+                base,
+                Some(&bearer),
+                vec![RpcCommand::RoomMintInvite {
+                    room: room.to_string(),
+                    capabilities: caps,
+                    max_uses: uses,
+                }],
+            )
+            .await?;
+            match rpc_line_ok(&batch.results[0])? {
+                RpcResult::RoomInviteMinted {
+                    invite_url,
+                    expires_at_ms,
+                    max_uses,
+                } => {
+                    if json {
+                        println!(
+                            "{}",
+                            serde_json::to_string_pretty(&serde_json::json!({
+                                "invite_url": invite_url,
+                                "expires_at_ms": expires_at_ms,
+                                "max_uses": max_uses,
+                            }))?
+                        );
+                    } else {
+                        println!("{invite_url}");
+                        println!("(Expires in 24 hours. Max uses: {max_uses})");
+                    }
+                }
+                _ => return Err(anyhow!("unexpected RPC result")),
+            }
+        }
+        ScopedCmd::Audit { json } => {
+            let bearer = effective_bearer().ok_or_else(|| {
+                anyhow!(
+                    "no bearer token: run `slugsocial identity start --rig <rig> --model <model>` \
+                     then `slugsocial identity poll <session>`, or set SLUG_BEARER_TOKEN / ~/.config/slugsocial/token"
+                )
+            })?;
+            let batch = send_rpc(
+                &client,
+                base,
+                Some(&bearer),
+                vec![RpcCommand::RoomAudit {
+                    room: room.to_string(),
+                }],
+            )
+            .await?;
+            match rpc_line_ok(&batch.results[0])? {
+                RpcResult::RoomAudit(resp) => {
+                    if json {
+                        println!("{}", serde_json::to_string_pretty(&resp)?);
+                    } else {
+                        println!("room {}", resp.room);
+                        if resp.grants.is_empty() {
+                            println!("(no grants recorded)");
+                        } else {
+                            let w_user = resp.grants.iter().map(|g| g.username.len()).max().unwrap_or(0);
+                            for g in &resp.grants {
+                                let caps = g.capabilities.join(", ");
+                                println!("{:<width$}  {}", g.username, caps, width = w_user.max(8));
+                            }
+                        }
+                    }
+                }
+                _ => return Err(anyhow!("unexpected RPC result")),
+            }
+        }
         ScopedCmd::Check { file, json } => {
             let mut text = String::new();
             match file {
diff --git a/server/src/api/auth.rs b/server/src/api/auth.rs
index 995ce4a61d29b024c399c656134f541ecfd880cf..b45ba39419c84af8bf2333fc9b7d47e98525c45f 100644
--- a/server/src/api/auth.rs
+++ b/server/src/api/auth.rs
@@ -12,12 +12,61 @@ use tokio::sync::RwLock;
 
 use crate::{
     api::helpers::{api_error, now_ms, sha256_hex},
-    events::{Event, TokenIssued, UserRegistered},
+    events::{Event, GrantAdded, TokenIssued, UserRegistered},
     identity::{parse_agent, parse_username},
     html::{auth_complete_page, auth_signed_in_fragment, choose_username_error_fragment, choose_username_page},
     state::{AppState, PendingSession},
 };
 
+/// Delegate id for browser users who land via `/join/inv_…` (no CLI agent).
+const INVITE_BROWSER_AGENT: &str = "00000000-0000-0000-0000-000000000000:invite:web/join";
+
+async fn apply_invite_redemption(state: &AppState, invite_token: &str, grantee_username: &str) -> Result<(), String> {
+    let now = now_ms();
+    let ga = {
+        let mut invites = state.invites.write().await;
+        let Some(inv) = invites.get_mut(invite_token) else {
+            return Err("invite not found".into());
+        };
+        if now > inv.expires_at_ms {
+            invites.remove(invite_token);
+            return Err("invite expired".into());
+        }
+        if inv.current_uses >= inv.max_uses {
+            return Err("invite exhausted".into());
+        }
+        inv.current_uses += 1;
+        Event::GrantAdded(GrantAdded {
+            ts: now,
+            room_id: inv.room_id.clone(),
+            username: grantee_username.to_string(),
+            capabilities: inv.capabilities.clone(),
+            granted_by: inv.inviter.clone(),
+        })
+    };
+
+    match state.event_log.append(&ga).await {
+        Ok(()) => {
+            let mut reduced = state.reduced.write().await;
+            reduced.apply_event(ga);
+            let mut invites = state.invites.write().await;
+            if let Some(inv) = invites.get(invite_token) {
+                if inv.current_uses >= inv.max_uses {
+                    invites.remove(invite_token);
+                }
+            }
+            Ok(())
+        }
+        Err(e) => {
+            let mut invites = state.invites.write().await;
+            if let Some(inv) = invites.get_mut(invite_token) {
+                inv.current_uses = inv.current_uses.saturating_sub(1);
+            }
+            Err(format!("{e}"))
+        }
+    }
+}
+
 fn pending_sessions(state: &AppState) -> Arc<RwLock<HashMap<String, PendingSession>>> {
     state.pending_sessions.clone()
 }
@@ -115,6 +164,42 @@ pub struct AuthLoginQuery {
     pub session: String,
 }
 
+pub async fn get_join_invite(Path(token): Path<String>, State(state): State<AppState>) -> impl IntoResponse {
+    let token = token.trim().to_string();
+    if token.is_empty() {
+        return api_error(StatusCode::NOT_FOUND, "invite invalid or expired", None).into_response();
+    }
+    let now = now_ms();
+    let valid = {
+        let invites = state.invites.read().await;
+        match invites.get(&token) {
+            None => false,
+            Some(inv) => now <= inv.expires_at_ms && inv.current_uses < inv.max_uses,
+        }
+    };
+    if !valid {
+        return api_error(StatusCode::NOT_FOUND, "invite invalid or expired", None).into_response();
+    }
+
+    let session = format!("p_{}", uuid::Uuid::new_v4().simple());
+    let s = PendingSession {
+        agent: INVITE_BROWSER_AGENT.to_string(),
+        created_ts: now_ms(),
+        provider: None,
+        provider_id: None,
+        redeem_invite: Some(token),
+        complete: None,
+    };
+    state.pending_sessions.write().await.insert(session.clone(), s);
+
+    let public_url = std::env::var("SLUG_PUBLIC_URL").unwrap_or_else(|_| "http://127.0.0.1:8080".to_string());
+    Redirect::temporary(&format!(
+        "{public_url}/auth/login?session={}",
+        urlencoding::encode(&session)
+    ))
+    .into_response()
+}
+
 pub async fn get_auth_login(Query(q): Query<AuthLoginQuery>, State(state): State<AppState>) -> impl IntoResponse {
     // Redirect to Google auth endpoint.
     let sessions = pending_sessions(&state);
@@ -205,6 +290,7 @@ pub async fn get_auth_callback(Query(q): Query<AuthCallbackQuery>, State(state):
         s.provider = Some("google".to_string());
         s.provider_id = Some(sub.clone());
         if let Some(username) = existing {
+            let invite_tok = s.redeem_invite.clone();
             let (bearer, token_event) = issue_token_for_user(&username);
             // append token event
             let ev = Event::TokenIssued(token_event);
@@ -215,6 +301,11 @@ pub async fn get_auth_callback(Query(q): Query<AuthCallbackQuery>, State(state):
                 let mut reduced = reduced_arc.write().await;
                 reduced.apply_event(ev);
             }
+            if let Some(tok) = invite_tok {
+                if let Err(e) = apply_invite_redemption(&state, &tok, &username).await {
+                    tracing::warn!(error = %e, "invite redemption skipped after oauth");
+                }
+            }
             s.complete = Some((username, bearer));
             return Redirect::temporary(&format!("{public_url}/auth/complete")).into_response();
         }
@@ -310,6 +401,16 @@ pub async fn post_choose_username(
         reduced.apply_event(ti_ev.clone());
     }
 
+    // Redeem invite (if any) before marking the session complete.
+    if let Some(tok) = {
+        let sessions_read = sessions.read().await;
+        sessions_read.get(&form.session).and_then(|s| s.redeem_invite.clone())
+    } {
+        if let Err(e) = apply_invite_redemption(&state, &tok, &canon_user).await {
+            tracing::warn!(error = %e, "invite redemption skipped after registration");
+        }
+    }
+
     // Mark complete for polling.
     {
         let mut sessions_write = sessions.write().await;
@@ -339,6 +440,7 @@ pub async fn post_pending_session(
         created_ts: now_ms(),
         provider: None,
         provider_id: None,
+        redeem_invite: None,
         complete: None,
     };
     let sessions = pending_sessions(&state);
diff --git a/server/src/api/mod.rs b/server/src/api/mod.rs
index a1ea432932cdca0e42dc7377f0a25075fd5644c0..cb031aecebad1107dfa2898a98fb6084b28ba6e9 100644
--- a/server/src/api/mod.rs
+++ b/server/src/api/mod.rs
@@ -4,6 +4,7 @@ mod rpc;
 mod validate;
 
 pub use auth::{
+    get_join_invite,
     get_pending_session,
     get_whoami,
     post_pending_session,
diff --git a/server/src/api/rpc.rs b/server/src/api/rpc.rs
index 11a76ed7a02aae588edadb7a87a43660f5669d9e..f6bbc3df71909a2da7403cd46fe4ea6ca130c692 100644
--- a/server/src/api/rpc.rs
+++ b/server/src/api/rpc.rs
@@ -13,12 +13,14 @@ use slug_types::*;
 use crate::{
     canonical_path::{canonicalize_item, canonicalize_tag},
     dsl,
-    events::{AgentBound, Event, GrantAdded, Ingest, RoomCreated, ThreadCapability, ThreadVisibility},
+    events::{
+        AgentBound, Event, GrantAdded, Ingest, RoomCreated, ThreadCapability, ThreadVisibility,
+    },
     identity::{parse_agent, parse_username},
     path_types::CanonicalItemUrl,
     ranking::{connected_components_from_voted_pairs, ranked_items_subset},
     reducer::{scope_from_room_wire, ReducerState, ScopeId},
-    state::AppState,
+    state::{AppState, InviteState},
 };
 
 use super::auth::verify_bearer_principal;
@@ -142,6 +144,27 @@ fn gen_short_id() -> String {
     (0..7).map(|_| ALPHABET[rng.gen_range(0..ALPHABET.len())] as char).collect()
 }
 
+fn gen_invite_token() -> String {
+    use rand::Rng;
+    const ALPHABET: &[u8] = b"0123456789abcdefghijklmnopqrstuvwxyz";
+    let mut rng = rand::thread_rng();
+    let tail: String = (0..16).map(|_| ALPHABET[rng.gen_range(0..ALPHABET.len())] as char).collect();
+    format!("inv_{tail}")
+}
+
+const INVITE_TTL_MS: i64 = 86_400_000;
+
+fn capability_wire(c: ThreadCapability) -> String {
+    match c {
+        ThreadCapability::View => "view",
+        ThreadCapability::Post => "post",
+        ThreadCapability::Vote => "vote",
+        ThreadCapability::AddItem => "add_item",
+        ThreadCapability::Manage => "manage",
+    }
+    .to_string()
+}
+
 fn build_rank_response_for_content(
     content: &crate::reducer::ContentState,
     parent: Option<&str>,
@@ -512,7 +535,7 @@ fn rpc_forum_thread_detail(
             None => Err(("post not found".into(), None)),
             Some((idx, ing)) => Ok(ThreadDetailResponse {
                 thread: format!("#{}", tag),
-                posts: vec![PostRow {
+                items: vec![ThreadItem::Post {
                     id: ing.id.clone(),
                     index: idx,
                     ts: ing.ts,
@@ -543,7 +566,7 @@ fn rpc_forum_thread_detail(
 
     let total = filtered.len();
     const MAX_BODY: usize = 2000;
-    let posts: Vec<PostRow> = filtered
+    let items: Vec<ThreadItem> = filtered
         .into_iter()
         .skip(offset)
         .take(limit)
@@ -553,7 +576,7 @@ fn rpc_forum_thread_detail(
             } else {
                 (ing.raw.clone(), false)
             };
-            PostRow {
+            ThreadItem::Post {
                 id: ing.id.clone(),
                 index: idx,
                 ts: ing.ts,
@@ -566,7 +589,7 @@ fn rpc_forum_thread_detail(
 
     Ok(ThreadDetailResponse {
         thread: format!("#{}", tag),
-        posts,
+        items,
         total,
         offset,
     })
@@ -1007,7 +1030,7 @@ pub async fn handle_rpc_batch(
             RpcCommand::RoomGrant {
                 room,
                 username,
-                capability,
+                capabilities,
             } => {
                 let principal = {
                     let reduced = state.reduced.read().await;
@@ -1022,6 +1045,8 @@ pub async fn handle_rpc_batch(
                         };
                         if !can_manage {
                             line_err("requires Manage capability", None)
+                        } else if capabilities.is_empty() {
+                            line_err("capabilities must not be empty", None)
                         } else {
                             match parse_username(&username) {
                                 Err(msg) => line_err("invalid username", Some(msg)),
@@ -1033,14 +1058,18 @@ pub async fn handle_rpc_batch(
                                     if !user_exists {
                                         line_err(format!("user @{target} not found"), None)
                                     } else {
-                                        match parse_capability(&capability) {
+                                        let caps: Result<Vec<ThreadCapability>, String> = capabilities
+                                            .iter()
+                                            .map(|c| parse_capability(c.trim()))
+                                            .collect();
+                                        match caps {
                                             Err(msg) => line_err(msg, None),
-                                            Ok(cap) => {
+                                            Ok(caps) => {
                                                 let ga_ev = Event::GrantAdded(GrantAdded {
                                                     ts: now_ms(),
                                                     room_id: room,
                                                     username: target,
-                                                    capabilities: vec![cap],
+                                                    capabilities: caps,
                                                     granted_by: principal,
                                                 });
                                                 if let Err(e) = state.event_log.append(&ga_ev).await {
@@ -1059,6 +1088,114 @@ pub async fn handle_rpc_batch(
                     }
                 }
             }
+            RpcCommand::RoomMintInvite {
+                room,
+                capabilities,
+                max_uses,
+            } => {
+                let principal = {
+                    let reduced = state.reduced.read().await;
+                    verify_bearer_principal(&headers, &*reduced)
+                };
+                match principal {
+                    Err((_, m)) => line_err(m, None),
+                    Ok(principal) => {
+                        let can_manage = {
+                            let reduced = state.reduced.read().await;
+                            reduced.user_has_cap(&room, &principal, ThreadCapability::Manage)
+                        };
+                        if !can_manage {
+                            line_err("requires Manage capability", None)
+                        } else if capabilities.is_empty() {
+                            line_err("capabilities must not be empty", None)
+                        } else {
+                            match capabilities
+                                .iter()
+                                .map(|c| parse_capability(c.trim()))
+                                .collect::<Result<Vec<ThreadCapability>, String>>()
+                            {
+                                Err(msg) => line_err(msg, None),
+                                Ok(caps) => {
+                                    let max_uses = max_uses.max(1).min(100_000);
+                                    let now = now_ms();
+                                    let expires_at_ms = now + INVITE_TTL_MS;
+                                    let token = loop {
+                                        let t = gen_invite_token();
+                                        let taken = {
+                                            let invites = state.invites.read().await;
+                                            invites.contains_key(&t)
+                                        };
+                                        if !taken {
+                                            break t;
+                                        }
+                                    };
+                                    let inv = InviteState {
+                                        room_id: room.clone(),
+                                        capabilities: caps,
+                                        expires_at_ms,
+                                        max_uses,
+                                        current_uses: 0,
+                                        inviter: principal,
+                                    };
+                                    state.invites.write().await.insert(token.clone(), inv);
+                                    let public_url = std::env::var("SLUG_PUBLIC_URL")
+                                        .unwrap_or_else(|_| "http://127.0.0.1:8080".to_string());
+                                    let invite_url = format!("{public_url}/join/{token}");
+                                    line_ok(RpcResult::RoomInviteMinted {
+                                        invite_url,
+                                        expires_at_ms: Some(expires_at_ms),
+                                        max_uses,
+                                    })
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            RpcCommand::RoomAudit { room } => {
+                let principal = {
+                    let reduced = state.reduced.read().await;
+                    verify_bearer_principal(&headers, &*reduced)
+                };
+                match principal {
+                    Err((_, m)) => line_err(m, None),
+                    Ok(principal) => {
+                        let reduced = state.reduced.read().await;
+                        if !reduced.rooms.contains_key(&room) {
+                            line_err("unknown room", None)
+                        } else {
+                            let can_audit = reduced.user_has_cap(&room, &principal, ThreadCapability::View)
+                                || reduced.user_has_cap(&room, &principal, ThreadCapability::Manage);
+                            if !can_audit {
+                                line_err("requires View or Manage capability", None)
+                            } else {
+                                let grants: Vec<RoomAuditEntry> = reduced
+                                    .grants
+                                    .get(&room)
+                                    .map(|m| {
+                                        let mut v: Vec<RoomAuditEntry> = m
+                                            .iter()
+                                            .map(|(username, caps)| {
+                                                let mut c: Vec<String> =
+                                                    caps.iter().copied().map(capability_wire).collect();
+                                                c.sort();
+                                                RoomAuditEntry {
+                                                    username: username.clone(),
+                                                    capabilities: c,
+                                                }
+                                            })
+                                            .collect();
+                                        v.sort_by(|a, b| a.username.cmp(&b.username));
+                                        v
+                                    })
+                                    .unwrap_or_default();
+                                line_ok(RpcResult::RoomAudit(RoomAuditResponse { room, grants }))
+                            }
+                        }
+                    }
+                }
+            }
+            RpcCommand::RoomRevoke { .. } => line_err("RoomRevoke is not implemented yet", None),
             RpcCommand::GetGlobalRank {
                 room,
                 limit,
diff --git a/server/src/events.rs b/server/src/events.rs
index 125005d89ade7b22c9b6d997f0ed81781df5e7ec..9e60f2c218f5c871a93e855e415dd984e3a017c5 100644
--- a/server/src/events.rs
+++ b/server/src/events.rs
@@ -26,6 +26,8 @@ pub enum Event {
     RoomCreated(RoomCreated),
     GrantAdded(GrantAdded),
     GrantRevoked(GrantRevoked),
+    InviteMinted(InviteMinted),
+    InviteRedeemed(InviteRedeemed),
     /// Ingest of a DSL+prose body. Identity and routing live in event metadata.
     Ingest(Ingest),
 }
@@ -82,6 +84,25 @@ pub struct GrantRevoked {
     pub revoked_by: String,
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub struct InviteMinted {
+    pub ts: i64,
+    pub token: String,
+    pub room_id: String,
+    pub capabilities: Vec<ThreadCapability>,
+    pub inviter: String,
+    pub max_uses: u32,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub expires_ts_ms: Option<i64>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub struct InviteRedeemed {
+    pub ts: i64,
+    pub token: String,
+    pub username: String,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
 pub struct Ingest {
     /// Unix timestamp in milliseconds.
diff --git a/server/src/lib.rs b/server/src/lib.rs
index d00b56d909e1fabd1d122d054dd02785e13e0bd8..bf2f73d4d0f26a357961e88c52c3b4f72626af81 100644
--- a/server/src/lib.rs
+++ b/server/src/lib.rs
@@ -27,6 +27,7 @@ pub fn create_app(state: AppState) -> Router {
     Router::new()
         .route("/healthz", axum::routing::get(|| async { "ok" }))
         .route("/static/:filename", axum::routing::get(crate::html::serve_theme_css))
+        .route("/join/:token", axum::routing::get(api::get_join_invite))
         .route("/auth/login", axum::routing::get(api::get_auth_login))
         .route("/auth/callback", axum::routing::get(api::get_auth_callback))
         .route("/auth/complete", axum::routing::get(api::get_auth_complete))
diff --git a/server/src/reducer.rs b/server/src/reducer.rs
index 118cb19f4df4a083df2878ca7a1424f3d63de851..5190d0a7ee3d545a786a68fef483322aafdce7f9 100644
--- a/server/src/reducer.rs
+++ b/server/src/reducer.rs
@@ -3,7 +3,7 @@ use std::collections::{HashMap, HashSet, VecDeque};
 use serde::{Deserialize, Serialize};
 
 use crate::canonical_path::canonicalize_tag;
-use crate::events::{Event, Ingest, ThreadCapability};
+use crate::events::{Event, Ingest, ThreadCapability, ThreadVisibility};
 use crate::path_types::CanonicalItemUrl;
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
@@ -156,6 +156,41 @@ pub struct RoomState {
     pub visibility: crate::events::ThreadVisibility,
 }
 
+/// Durable invite link state (from [`crate::events::InviteMinted`] / [`crate::events::InviteRedeemed`]).
+#[derive(Debug, Clone)]
+pub struct ActiveInviteState {
+    pub room_id: String,
+    pub capabilities: HashSet<ThreadCapability>,
+    pub inviter: String,
+    pub uses_remaining: u32,
+    pub expires_ts_ms: Option<i64>,
+}
+
+#[derive(Clone, Debug)]
+pub enum RoomTimelineKind {
+    RoomCreated {
+        owner: String,
+        slug: String,
+        visibility: ThreadVisibility,
+    },
+    GrantAdded {
+        username: String,
+        granted_by: String,
+        capabilities: Vec<ThreadCapability>,
+    },
+    GrantRevoked {
+        username: String,
+        revoked_by: String,
+        capabilities: Vec<ThreadCapability>,
+    },
+}
+
+#[derive(Clone, Debug)]
+pub struct RoomTimelineEntry {
+    pub ts: i64,
+    pub kind: RoomTimelineKind,
+}
+
 #[derive(Debug, Clone)]
 pub struct ForumThreadState {
     pub last_activity_ts: i64,
@@ -210,6 +245,10 @@ pub struct ReducerState {
     pub ingests_ordered: Vec<String>,
     /// room_id → username → capabilities
     pub grants: HashMap<String, HashMap<String, HashSet<ThreadCapability>>>,
+    /// room_id → chronological room admin lines (for thread UI).
+    pub room_timeline: HashMap<String, Vec<RoomTimelineEntry>>,
+    /// Invite token → active invite (absent when fully consumed or never minted).
+    pub invites: HashMap<String, ActiveInviteState>,
 }
 
 impl ReducerState {
@@ -225,6 +264,20 @@ impl ReducerState {
             .unwrap_or(false)
     }
 
+    /// Invite link is present, not expired, and has uses left.
+    pub fn invite_token_active(&self, token: &str, now_ms: i64) -> Option<&ActiveInviteState> {
+        let inv = self.invites.get(token)?;
+        if inv.uses_remaining == 0 {
+            return None;
+        }
+        if let Some(exp) = inv.expires_ts_ms {
+            if now_ms > exp {
+                return None;
+            }
+        }
+        Some(inv)
+    }
+
     pub fn content_for_scope_mut(&mut self, scope: ScopeId) -> &mut ContentState {
         self.content.entry(scope).or_default()
     }
@@ -356,6 +409,17 @@ impl ReducerState {
                         visibility: rc.visibility,
                     },
                 );
+                self.room_timeline
+                    .entry(rc.room_id.clone())
+                    .or_default()
+                    .push(RoomTimelineEntry {
+                        ts: rc.ts,
+                        kind: RoomTimelineKind::RoomCreated {
+                            owner: rc.owner.clone(),
+                            slug: rc.slug.clone(),
+                            visibility: rc.visibility,
+                        },
+                    });
             }
             Event::Ingest(mut ing) => {
                 ing.thread_tag = canonicalize_tag(&ing.thread_tag);
@@ -525,18 +589,31 @@ impl ReducerState {
                 nav!(self.actor_last_post_ts, keypath(ing.principal.clone()), setval(ing.ts));
             }
             Event::GrantAdded(ga) => {
+                let room_id = ga.room_id.clone();
                 let caps = self.grants
                     .entry(ga.room_id)
                     .or_default()
-                    .entry(ga.username)
+                    .entry(ga.username.clone())
                     .or_default();
-                for cap in ga.capabilities {
+                for cap in ga.capabilities.iter().copied() {
                     caps.insert(cap);
                 }
+                self.room_timeline
+                    .entry(room_id)
+                    .or_default()
+                    .push(RoomTimelineEntry {
+                        ts: ga.ts,
+                        kind: RoomTimelineKind::GrantAdded {
+                            username: ga.username.clone(),
+                            granted_by: ga.granted_by.clone(),
+                            capabilities: ga.capabilities.clone(),
+                        },
+                    });
             }
             Event::GrantRevoked(gr) => {
+                let room_id = gr.room_id.clone();
                 if let Some(room_grants) = self.grants.get_mut(&gr.room_id) {
-                    let username = gr.username;
+                    let username = gr.username.clone();
                     if let Some(caps) = room_grants.get_mut(&username) {
                         for cap in &gr.capabilities {
                             caps.remove(cap);
@@ -549,6 +626,37 @@ impl ReducerState {
                         self.grants.remove(&gr.room_id);
                     }
                 }
+                self.room_timeline
+                    .entry(room_id)
+                    .or_default()
+                    .push(RoomTimelineEntry {
+                        ts: gr.ts,
+                        kind: RoomTimelineKind::GrantRevoked {
+                            username: gr.username.clone(),
+                            revoked_by: gr.revoked_by.clone(),
+                            capabilities: gr.capabilities.clone(),
+                        },
+                    });
+            }
+            Event::InviteMinted(im) => {
+                self.invites.insert(
+                    im.token.clone(),
+                    ActiveInviteState {
+                        room_id: im.room_id.clone(),
+                        capabilities: im.capabilities.iter().copied().collect(),
+                        inviter: im.inviter.clone(),
+                        uses_remaining: im.max_uses,
+                        expires_ts_ms: im.expires_ts_ms,
+                    },
+                );
+            }
+            Event::InviteRedeemed(ir) => {
+                if let Some(inv) = self.invites.get_mut(&ir.token) {
+                    inv.uses_remaining = inv.uses_remaining.saturating_sub(1);
+                    if inv.uses_remaining == 0 {
+                        self.invites.remove(&ir.token);
+                    }
+                }
             }
         }
     }
@@ -570,6 +678,8 @@ impl Default for ReducerState {
             actor_last_post_ts: HashMap::new(),
             ingests_ordered: Vec::new(),
             grants: HashMap::new(),
+            room_timeline: HashMap::new(),
+            invites: HashMap::new(),
         }
     }
 }
diff --git a/server/src/state.rs b/server/src/state.rs
index b1ff2330903780cbe0cdf35964cb166eb2423d7d..628fd5921b34ba53ac0ca6b6fd33957ca09129b9 100644
--- a/server/src/state.rs
+++ b/server/src/state.rs
@@ -1,8 +1,20 @@
+use std::collections::HashMap;
 use std::sync::Arc;
 
 use tokio::sync::{broadcast, RwLock};
 
-use crate::{event_log::EventLog, reducer::ReducerState};
+use crate::{event_log::EventLog, events::ThreadCapability, reducer::ReducerState};
+
+/// Ephemeral invite link (24h TTL, in-memory only; not written to the event log).
+#[derive(Debug, Clone)]
+pub struct InviteState {
+    pub room_id: String,
+    pub capabilities: Vec<ThreadCapability>,
+    pub expires_at_ms: i64,
+    pub max_uses: usize,
+    pub current_uses: usize,
+    pub inviter: String,
+}
 
 #[derive(Debug, Clone)]
 pub struct PendingSession {
@@ -10,6 +22,8 @@ pub struct PendingSession {
     pub created_ts: i64,
     pub provider: Option<String>,
     pub provider_id: Option<String>,
+    /// When set, successful OAuth completion redeems this invite token and appends [`crate::events::GrantAdded`].
+    pub redeem_invite: Option<String>,
     pub complete: Option<(String /*username*/, String /*bearer*/ )>,
 }
 
@@ -42,7 +56,9 @@ pub struct AppState {
     pub cfg: Arc<AppConfig>,
     pub event_log: Arc<EventLog>,
     pub reduced: Arc<RwLock<ReducerState>>,
-    pub pending_sessions: Arc<RwLock<std::collections::HashMap<String, PendingSession>>>,
+    pub pending_sessions: Arc<RwLock<HashMap<String, PendingSession>>>,
+    /// Ephemeral invite tokens (`inv_…`) until expiry or exhaustion.
+    pub invites: Arc<RwLock<HashMap<String, InviteState>>>,
     /// Broadcast channel for SSE live-streaming. Capacity = 64 events.
     pub stream_tx: broadcast::Sender<StreamEvent>,
     /// Broadcast channel for web SSE HTML fragments (poem pattern). Capacity = 64.
@@ -58,7 +74,8 @@ impl AppState {
             cfg: Arc::new(cfg),
             event_log: Arc::new(event_log),
             reduced: Arc::new(RwLock::new(ReducerState::default())),
-            pending_sessions: Arc::new(RwLock::new(std::collections::HashMap::new())),
+            pending_sessions: Arc::new(RwLock::new(HashMap::new())),
+            invites: Arc::new(RwLock::new(HashMap::new())),
             stream_tx,
             html_tx,
         }
diff --git a/server/src/timeline.rs b/server/src/timeline.rs
new file mode 100644
index 0000000000000000000000000000000000000000..251158943ab36d3015268e35f6bdd01c3f42ab3b
--- /dev/null
+++ b/server/src/timeline.rs
@@ -0,0 +1,153 @@
+//! Room admin lines merged into forum thread views.
+
+use crate::{
+    canonical_path::canonicalize_tag,
+    reducer::{ReducerState, RoomTimelineEntry, RoomTimelineKind},
+};
+
+fn cap_label(c: crate::events::ThreadCapability) -> &'static str {
+    use crate::events::ThreadCapability::*;
+    match c {
+        View => "view",
+        Post => "post",
+        Vote => "vote",
+        AddItem => "add_item",
+        Manage => "manage",
+    }
+}
+
+fn caps_list(caps: &[crate::events::ThreadCapability]) -> String {
+    let mut v: Vec<_> = caps.iter().map(|c| cap_label(*c)).collect();
+    v.sort();
+    v.join(", ")
+}
+
+/// Human-readable system line for the thread feed.
+pub fn format_room_timeline_entry(e: &RoomTimelineEntry) -> String {
+    match &e.kind {
+        RoomTimelineKind::RoomCreated {
+            owner,
+            slug,
+            visibility,
+        } => {
+            let vis = match visibility {
+                crate::events::ThreadVisibility::Public => "public",
+                crate::events::ThreadVisibility::Private => "private",
+            };
+            format!("@{owner} created room #{slug} ({vis})")
+        }
+        RoomTimelineKind::GrantAdded {
+            username,
+            granted_by,
+            capabilities,
+        } => {
+            format!(
+                "@{granted_by} granted @{} {}",
+                username,
+                caps_list(capabilities)
+            )
+        }
+        RoomTimelineKind::GrantRevoked {
+            username,
+            revoked_by,
+            capabilities,
+        } => {
+            format!(
+                "@{revoked_by} revoked @{} {}",
+                username,
+                caps_list(capabilities)
+            )
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub enum MergedThreadRow {
+    System { ts: i64, text: String },
+    Post {
+        index: usize,
+        id: String,
+        ts: i64,
+        principal: String,
+        raw: String,
+    },
+}
+
+/// Merge room admin lines with thread ingests for one room + tag. Oldest first.
+/// `actor_prefix` filters posts only (system lines always included).
+pub fn merge_thread_rows(
+    reduced: &ReducerState,
+    room_wire: &str,
+    thread_tag: &str,
+    since: Option<i64>,
+    before: Option<i64>,
+    actor_prefix: &str,
+) -> Vec<MergedThreadRow> {
+    let scope = crate::reducer::scope_from_room_wire(room_wire);
+    let tag = canonicalize_tag(thread_tag);
+    let key = (scope.clone(), tag.clone());
+
+    let mut rows: Vec<MergedThreadRow> = Vec::new();
+
+    if let Some(entries) = reduced.room_timeline.get(room_wire.trim()) {
+        for e in entries {
+            if since.map_or(true, |s| e.ts >= s) && before.map_or(true, |b| e.ts < b) {
+                rows.push(MergedThreadRow::System {
+                    ts: e.ts,
+                    text: format_room_timeline_entry(e),
+                });
+            }
+        }
+    }
+
+    let all_ids: Vec<String> = reduced
+        .ingests_by_scope_thread
+        .get(&key)
+        .map(|q| q.iter().rev().cloned().collect())
+        .unwrap_or_default();
+
+    for (idx, id) in all_ids.into_iter().enumerate() {
+        let Some(ing) = reduced.ingests_by_id.get(&id) else {
+            continue;
+        };
+        if since.map_or(true, |s| ing.ts >= s) && before.map_or(true, |b| ing.ts < b) {
+            if !actor_prefix.is_empty()
+                && !ing
+                    .principal
+                    .to_lowercase()
+                    .starts_with(actor_prefix)
+            {
+                continue;
+            }
+            rows.push(MergedThreadRow::Post {
+                index: idx,
+                id: ing.id.clone(),
+                ts: ing.ts,
+                principal: ing.principal.clone(),
+                raw: ing.raw.clone(),
+            });
+        }
+    }
+
+    rows.sort_by(|a, b| {
+        let ta = match a {
+            MergedThreadRow::System { ts, .. } | MergedThreadRow::Post { ts, .. } => *ts,
+        };
+        let tb = match b {
+            MergedThreadRow::System { ts, .. } | MergedThreadRow::Post { ts, .. } => *ts,
+        };
+        ta.cmp(&tb)
+    });
+    rows
+}
+
+/// Public forum thread (`room_wire == "public"`): same merge (timeline usually empty).
+pub fn merge_public_thread_rows(
+    reduced: &ReducerState,
+    thread_tag: &str,
+    since: Option<i64>,
+    before: Option<i64>,
+    actor_prefix: &str,
+) -> Vec<MergedThreadRow> {
+    merge_thread_rows(reduced, "public", thread_tag, since, before, actor_prefix)
+}
diff --git a/test/grants.bb b/test/grants.bb
index 10ef0f08ce1c3945e5f1634314e6aebcf6810cd2..4ded5ce92576cdea653cce0ba8a751be4374731a 100644
--- a/test/grants.bb
+++ b/test/grants.bb
@@ -105,7 +105,7 @@
        ;; Alice grants bob View only.
        (println "\nalice grants bob View only…")
        (assert! (rpc-line-ok? (:parsed (rpc-batch! base-url alice-token
-                                                   [{"RoomGrant" {"room" room-id "username" "bob" "capability" "view"}}])))
+                                                   [{"RoomGrant" {"room" room-id "username" "bob" "capabilities" ["view"]}}])))
                 "grant View RPC ok")
 
        (println "\nbob (View only) tries to post prose…")
@@ -117,7 +117,7 @@
        ;; Alice grants bob Post.
        (println "\nalice grants bob Post…")
        (assert! (rpc-line-ok? (:parsed (rpc-batch! base-url alice-token
-                                                   [{"RoomGrant" {"room" room-id "username" "bob" "capability" "post"}}])))
+                                                   [{"RoomGrant" {"room" room-id "username" "bob" "capabilities" ["post"]}}])))
                 "grant Post RPC ok")
 
        (println "\nbob (View + Post) posts prose…")
@@ -143,7 +143,7 @@
        ;; Alice grants bob Vote.
        (println "\nalice grants bob Vote…")
        (assert! (rpc-line-ok? (:parsed (rpc-batch! base-url alice-token
-                                                   [{"RoomGrant" {"room" room-id "username" "bob" "capability" "vote"}}])))
+                                                   [{"RoomGrant" {"room" room-id "username" "bob" "capabilities" ["vote"]}}])))
                 "grant Vote RPC ok")
 
        (println "\nbob (View + Post + Vote) votes…")
diff --git a/test/invites.bb b/test/invites.bb
new file mode 100644
index 0000000000000000000000000000000000000000..f72b1e630a6856174cdef11eb977e2f81b16e551
--- /dev/null
+++ b/test/invites.bb
@@ -0,0 +1,150 @@
+(ns test.invites
+  "Ephemeral invite links: mint via RPC, GET /join → pending session + OAuth, redemption → GrantAdded,
+  RoomAudit, post succeeds, second GET /join returns 404 when max_uses exhausted."
+  (:require [babashka.fs :as fs]
+            [cheshire.core :as json]
+            [clojure.string :as str]
+            [test.common :as common]
+            [test.oauth :as oauth]))
+
+(def ^:private counts (atom {:pass 0 :fail 0}))
+
+(defn- assert! [pred msg]
+  (common/test-assert! counts pred msg))
+
+(defn- bearer [token] {"Authorization" (str "Bearer " token)})
+
+(defn- rpc-batch! [base-url token cmds]
+  (let [resp (oauth/http-post-json (str base-url "/api/v0/rpc") cmds :headers (bearer token))]
+    {:status (:status resp)
+     :parsed (json/parse-string (:body resp) false)}))
+
+(defn- rpc-line-ok? [parsed]
+  (true? (get-in parsed ["results" 0 "ok"])))
+
+(defn- session-from-login-location [loc]
+  (when loc
+    (let [qpart (if (str/includes? loc "?")
+                  (-> loc (str/split #"\?" 2) second)
+                  "")
+          qpart (if (str/includes? qpart "#")
+                  (-> qpart (str/split #"#" 2) first)
+                  qpart)
+          m (oauth/parse-query qpart)]
+      (some-> (get m :session) str))))
+
+(defn- invite-token-from-url [invite-url]
+  (second (re-find #"/join/(inv_[^/?#]+)" (str invite-url))))
+
+(defn- register-user! [base-url session-agent username]
+  (oauth/complete-registration! base-url
+                                :agent session-agent
+                                :username username
+                                :assert! (fn [pred msg] (assert! pred msg))))
+
+(defn- ingest! [base-url token room thread delegate text]
+  (rpc-batch! base-url token
+              [{"Post" {"room" room
+                        "thread_tag" thread
+                        "delegate" delegate
+                        "text" text
+                        "return_rank_diff" false}}]))
+
+(defn invites-test [& _args]
+  (println "\n━━━ ephemeral invite + audit integration check ━━━\n")
+  (reset! counts {:pass 0 :fail 0})
+
+  (println "building server binary…")
+  (common/letlocals
+   (bind build (common/run-cargo-build-release! ["slugsocial-server"]))
+   (assert! (zero? (:exit build)) "cargo build succeeds")
+   (bind server-bin "target/release/slugsocial-server")
+
+   (bind tmp-dir (str (fs/create-temp-dir {:prefix "slug-invites-"})))
+   (bind slug-port (common/pick-port))
+   (bind google-port (common/pick-port))
+   (bind base-url (str "http://127.0.0.1:" slug-port))
+   (bind google-url (str "http://127.0.0.1:" google-port))
+
+   (bind !server (atom nil))
+   (bind !google (atom nil))
+
+   (bind server-env (common/slug-server-env tmp-dir base-url google-url slug-port))
+   (try
+     (println (str "starting mock google on :" google-port))
+     (reset! !google (oauth/start-mock-google google-port
+                                              :google-users ["google-user-alice" "google-user-bob"]))
+
+     (println (str "starting server on :" slug-port))
+     (reset! !server (common/start-server server-bin server-env))
+     (assert! (common/wait-for-server base-url 10000) "server responds to /healthz")
+
+     (println "\nregistering alice…")
+     (let [alice-token (register-user! base-url
+                                       "00000000-0000-0000-0000-000000000001:test:local/dev"
+                                       "alice")
+
+           _ (println "\nalice creates private room…")
+           create (rpc-batch! base-url alice-token
+                              [{"RoomCreate" {"slug" "invite-demo" "visibility" "private"}}])
+           _ (assert! (= 200 (:status create)) "room create HTTP 200")
+           _ (assert! (rpc-line-ok? (:parsed create)) "room create RPC ok")
+           room-id (get-in (:parsed create) ["results" 0 "result" "RoomCreated" "room_id"])
+           _ (assert! (some? room-id) "room_id present")
+
+           _ (println "\nalice mints invite (view,post,vote uses=1)…")
+           mint (rpc-batch! base-url alice-token
+                            [{"RoomMintInvite" {"room" room-id
+                                                "capabilities" ["view" "post" "vote"]
+                                                "max_uses" 1}}])
+           _ (assert! (= 200 (:status mint)) "mint HTTP 200")
+           _ (assert! (rpc-line-ok? (:parsed mint)) "mint RPC ok")
+           invite-url (get-in (:parsed mint) ["results" 0 "result" "RoomInviteMinted" "invite_url"])
+           inv-tok (invite-token-from-url invite-url)
+           _ (assert! (some? inv-tok) "invite token parsed from URL")
+
+           _ (println "\nGET /join/:token (expect redirect + session)…")
+           join-resp (oauth/http-get-no-redirect (str base-url "/join/" inv-tok))
+           _ (assert! (contains? #{302 307} (:status join-resp))
+                      (str "join returns redirect (got status " (:status join-resp) ")"))
+           sess (session-from-login-location (:location join-resp))
+           _ (assert! (and (some? sess) (str/starts-with? sess "p_")) "Location carries session=p_…")
+
+           _ (println "\nbob completes OAuth via invite session…")
+           bob-token (oauth/complete-pending-session! base-url sess "bob"
+                                                      :assert! (fn [pred msg] (assert! pred msg)))
+
+           _ (println "\nalice runs RoomAudit…")
+           audit (rpc-batch! base-url alice-token [{"RoomAudit" {"room" room-id}}])
+           _ (assert! (rpc-line-ok? (:parsed audit)) "audit RPC ok")
+           grants (get-in (:parsed audit) ["results" 0 "result" "RoomAudit" "grants"])
+           bob-entry (first (filter #(= "bob" (get % "username")) grants))
+           _ (assert! (some? bob-entry) "audit lists bob")
+           bob-caps (set (get bob-entry "capabilities"))
+           _ (assert! (= bob-caps #{"view" "post" "vote"}) "bob has view, post, vote")
+
+           _ (println "\nbob posts prose to private room…")
+           _ (assert! (rpc-line-ok? (:parsed (ingest! base-url bob-token room-id "main"
+                                                      "00000000-0000-0000-0000-000000000002:test:local/dev"
+                                                      "Hello via invite link.")))
+                      "bob post succeeds")
+
+           _ (println "\nsecond GET /join (invite exhausted → 404)…")
+           join2 (oauth/http-get-no-redirect (str base-url "/join/" inv-tok))
+           _ (assert! (= 404 (:status join2)) "exhausted invite returns 404")]
+
+       (println "\ninvite lifecycle OK."))
+
+     (finally
+       (when-some [s @!server] (common/kill-server s))
+       (when-some [g @!google] ((:stop-fn g)))
+       (fs/delete-tree tmp-dir)))
+
+   (bind {pass :pass fail :fail} @counts)
+   (if (zero? fail)
+     (println (str "\n" common/ansi-green "━━━ " pass " invite checks passed ━━━" common/ansi-reset "\n"))
+     (do (println (str "\n" common/ansi-red "━━━ " fail " invite checks FAILED ━━━" common/ansi-reset "\n"))
+         (System/exit 1)))))
+
+(when (= *file* (System/getProperty "babashka.file"))
+  (invites-test))
diff --git a/test/oauth.bb b/test/oauth.bb
index b69459acd17c23c023170d8dd93fe45bb49c8d88..efb3f3e66346ffde81bf9622d75c3a6ec89f8db2 100644
--- a/test/oauth.bb
+++ b/test/oauth.bb
@@ -21,6 +21,21 @@
           resp (.send (http-client) req (java.net.http.HttpResponse$BodyHandlers/ofString))]
       {:status (.statusCode resp) :body (.body resp) :headers (.map (.headers resp))})))
 
+(defn http-get-no-redirect
+  "GET without following redirects; returns `:location` from the first `Location` header when present."
+  [url & {:keys [headers]}]
+  (let [client (-> (java.net.http.HttpClient/newBuilder)
+                   (.followRedirects java.net.http.HttpClient$Redirect/NEVER)
+                   (.connectTimeout connect-timeout)
+                   (.build))
+        b (java.net.http.HttpRequest/newBuilder (java.net.URI/create url))]
+    (doseq [[k v] (or headers {})]
+      (.header b k v))
+    (let [req (-> b (.timeout request-timeout) (.GET) (.build))
+          resp (.send client req (java.net.http.HttpResponse$BodyHandlers/ofString))
+          loc (first (get (.map (.headers resp)) "location"))]
+      {:status (.statusCode resp) :body (.body resp) :location loc})))
+
 (defn http-post-json [url data & {:keys [headers]}]
   (let [body (json/generate-string data)
         b (java.net.http.HttpRequest/newBuilder (java.net.URI/create url))]
@@ -50,6 +65,35 @@
           resp (.send (http-client) req (java.net.http.HttpResponse$BodyHandlers/ofString))]
       {:status (.statusCode resp) :body (.body resp) :headers (.map (.headers resp))})))
 
+(defn complete-pending-session!
+  "Finish OAuth for an existing pending session id (e.g. created by `GET /join/inv_…`). Returns bearer token."
+  [base-url session-id username & {:keys [assert!]}]
+  (let [check! (fn [pred msg resp]
+                 (if assert!
+                   (assert! pred msg)
+                   (when-not pred
+                     (throw (ex-info msg {:resp resp})))))]
+    (let [enc (java.net.URLEncoder/encode session-id "UTF-8")
+          login-url (str base-url "/auth/login?session=" enc)
+          login-get (http-get login-url)]
+      (check! (= 200 (:status login-get))
+              (str "oauth redirect chain for session " session-id)
+              login-get)
+      (let [choose (http-post-form (str base-url "/auth/choose-username")
+                                   {:session session-id :username username})]
+        (check! (= 200 (:status choose))
+                (str "choose-username for " username " returns 200")
+                choose)
+        (let [poll (http-get (str base-url "/api/v0/pending-session/" session-id))]
+          (check! (= 200 (:status poll))
+                  (str "pending-session poll returns 200")
+                  poll)
+          (let [poll-json (json/parse-string (:body poll) true)]
+            (check! (:complete poll-json)
+                    (str "pending session complete for " username)
+                    poll)
+            (:token poll-json)))))))
+
 (defn parse-query [s]
   (into {}
         (for [part (str/split (or s "") #"&")
diff --git a/types/src/lib.rs b/types/src/lib.rs
index a715fe5639f4a3a7bfedcc706b5fb312b98c9ac5..98c66a00fd27803ef6f75b5ac478ff2eb762d771 100644
--- a/types/src/lib.rs
+++ b/types/src/lib.rs
@@ -123,13 +123,32 @@ pub struct PathDetailResponse {
 #[derive(Debug, Serialize, Deserialize)]
 pub struct ThreadDetailResponse {
     pub thread: String,
-    pub posts: Vec<PostRow>,
-    /// Total posts in this thread.
+    /// Chronological page: prose posts and room system lines, oldest first within the window.
+    pub items: Vec<ThreadItem>,
+    /// Total rows (posts + system lines) in this thread after filters.
     pub total: usize,
-    /// Chronological offset of the first post in this page.
+    /// Offset into the merged chronological list.
     pub offset: usize,
 }
 
+/// One row in a thread timeline: a normal post or a room system line.
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(tag = "kind", rename_all = "snake_case")]
+pub enum ThreadItem {
+    Post {
+        id: String,
+        index: usize,
+        ts: i64,
+        actor: String,
+        body: String,
+        truncated: bool,
+    },
+    System {
+        ts: i64,
+        text: String,
+    },
+}
+
 /// One post in a thread. Full body, no snippet.
 #[derive(Debug, Serialize, Deserialize)]
 pub struct PostRow {
@@ -224,6 +243,23 @@ pub struct FeedPost {
 // RPC batch API (`POST /api/v0/rpc`)
 // ---------------------------------------------------------------------------
 
+fn default_invite_max_uses() -> usize {
+    1
+}
+
+/// One principal's capabilities in a private room (from [`RpcCommand::RoomAudit`]).
+#[derive(Debug, Serialize, Deserialize)]
+pub struct RoomAuditEntry {
+    pub username: String,
+    pub capabilities: Vec<String>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct RoomAuditResponse {
+    pub room: String,
+    pub grants: Vec<RoomAuditEntry>,
+}
+
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(transparent)]
 pub struct RpcBatch(pub Vec<RpcCommand>);
@@ -287,10 +323,27 @@ pub enum RpcCommand {
         visibility: Option<String>,
     },
     RoomGrant {
+        room: String,
+        username: String,
+        /// Capability names: `view`, `post`, `vote`, `add_item`, `manage`.
+        capabilities: Vec<String>,
+    },
+    RoomRevoke {
         room: String,
         username: String,
         capability: String,
     },
+    /// Mint a shareable invite link (24h TTL, stored in memory only until redeemed or expiry).
+    RoomMintInvite {
+        room: String,
+        capabilities: Vec<String>,
+        #[serde(default = "default_invite_max_uses")]
+        max_uses: usize,
+    },
+    /// List principals granted access in a room (requires View or Manage).
+    RoomAudit {
+        room: String,
+    },
     GetGlobalRank {
         room: String,
         #[serde(default)]
@@ -361,6 +414,13 @@ pub enum RpcResult {
     RoomCreated {
         room_id: String,
     },
+    RoomInviteMinted {
+        invite_url: String,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        expires_at_ms: Option<i64>,
+        max_uses: usize,
+    },
+    RoomAudit(RoomAuditResponse),
     GrantOk {},
     GlobalRank(GlobalRankResponse),
     Pair(PairResponse),


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

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

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

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