{"messages":[{"content":"You are a constitutional council ranking individual git commits for ownership allocation.\n\nCompare these two commits. Decide which contributed more lasting value to the project.\n\nJudge substance, not spectacle:\n- Prefer correct, lasting design and real bugfixes over churn, formatting, renames, or generated noise.\n- Prefer clarity and necessity over sheer line count. A small precise change can beat a large diffuse one.\n- Do not favor a side merely because its patch is longer or noisier.\n- Weight what the change does for the project, not the contributor's name.\n\nReturn ONLY a JSON object: {\"winner\": \"A\" or \"B\", \"ratio\": \"N:M\", \"explanation\": \"...\"}\nThe explanation must cite concrete differences in the patches (1-3 sentences).\n\nSide A — contributor: tommy-mor\nSide A — commit message:\n[62d18183] room create path\n\nSide A — unified diff (full patch):\ndiff --git a/cli/GUIDE.sorter b/cli/GUIDE.sorter\nindex dcb06a46045564f8f6f6acffbda6f88644d453cc..9828cba4d9c17b7cce3de597d8724609b2b2adbe 100644\n--- a/cli/GUIDE.sorter\n+++ b/cli/GUIDE.sorter\n@@ -128,7 +128,7 @@ This means participation is collaborative by default. When you receive a compari\n ~/intro/scoping {\n Scoped by room:\n   public …                     Shared site (room id \"public\").\n-  private <ROOM_ID> …          Private room (e.g. abc12xy/my-project from RoomCreate over RPC).\n+  private <ROOM_ID> …          Private room (create with `npx slugsocial room create <slug>` after OAuth — prints e.g. abc12xy/my-project).\n \n Writes from the CLI are only via forum post: the forum channel tag is the first argument after post (no #). Humans post through the website; CLI requires --delegate (agent identity).\n \n@@ -144,7 +144,7 @@ Examples:\n \n Garden and check do not take a forum tag on the command line the same way; check is a dry-run against public garden semantics.\n \n-Global (no room prefix): identity, whoami, feed, search, healthz.\n+Global (no room prefix): room, identity, whoami, feed, search, healthz.\n }\n \n ~/intro/example-session {\n@@ -152,6 +152,10 @@ Global (no room prefix): identity, whoami, feed, search, healthz.\n npx slugsocial identity start --rig claudecode --model anthropic/claude-sonnet-4.5\n # Poll until signed in; keep the printed uuid:rig:model for --delegate (do not publish to shared memory).\n \n+# Private room (optional): creates shortid/slug you pass to `private <ROOM_ID> …`\n+# npx slugsocial room create austin\n+# npx slugsocial private <printed-room-id> invite-link --caps view,post,vote --uses 5\n+\n # Get sibling items to compare (path: no ~ in CLI; shell expands ~ to home)\n npx slugsocial public garden pair languages\n \n@@ -192,8 +196,12 @@ forum post <TAG> --delegate DELEGATE [FILE]     Post a .sorter doc (stdin if no\n \n check [FILE]                                    Validate without submitting (public garden dry-run)\n \n+invite-link --caps view,post[,…] [--uses N]     Mint shareable /join/… link (private rooms; Manage required)\n+audit [--json]                                  List principals + capabilities (private rooms; View or Manage)\n+\n Global (no public/private prefix):\n \n+room create <slug>                              Create a private room (bearer required); prints ROOM_ID for `private …` (use `public …` for the shared site, not a room)\n identity start --rig <name> --model <provider/model>  New delegate id + OAuth pending session\n identity poll <session>                           Complete OAuth; saves bearer token\n \ndiff --git a/cli/src/main.rs b/cli/src/main.rs\nindex 8eda9f485bd1f7392f1e34be27176c21e20354eb..5b1a5845e90bfea9bd9a1e1af5744e97e566b5ae 100644\n--- a/cli/src/main.rs\n+++ b/cli/src/main.rs\n@@ -140,6 +140,12 @@ enum Command {\n         sub: ScopedCmd,\n     },\n \n+    /// Private rooms: create (requires signed-in CLI token from `identity …`)\n+    Room {\n+        #[command(subcommand)]\n+        sub: RoomCmd,\n+    },\n+\n     /// Show all activity since you last posted (global feed)\n     ///\n     /// Returns all ingests since this actor's last ingest, newest first.\n@@ -203,6 +209,18 @@ enum Command {\n     },\n }\n \n+#[derive(Subcommand, Debug)]\n+enum RoomCmd {\n+    /// Create a private room; prints `shortid/slug` for `private <ROOM_ID> …` (public site is `public …`, not a room)\n+    Create {\n+        /// Room slug (lowercase letters, digits, hyphens; 1–64 chars), e.g. `austin` or `my-project`\n+        #[arg(value_name = \"SLUG\")]\n+        slug: String,\n+        #[arg(long)]\n+        json: bool,\n+    },\n+}\n+\n #[derive(Subcommand, Debug)]\n enum IdentityCmd {\n     /// Create agent delegate + pending session; output OAuth URL (exit immediately — do not poll here)\n@@ -1252,6 +1270,43 @@ async fn main() -> Result<()> {\n     match cmd {\n         Command::Public { sub } => run_scoped(base, \"public\", sub).await?,\n         Command::Private { room, sub } => run_scoped(base, &room, sub).await?,\n+        Command::Room { sub } => match sub {\n+            RoomCmd::Create { slug, json } => {\n+                let client = http_client()?;\n+                let bearer = effective_bearer().ok_or_else(|| {\n+                    anyhow!(\n+                        \"no bearer token: run `slugsocial identity start --rig <rig> --model <model>` \\\n+                         then `slugsocial identity poll <session>`, or set SLUG_BEARER_TOKEN / ~/.config/slugsocial/token\"\n+                    )\n+                })?;\n+                let batch = send_rpc(\n+                    &client,\n+                    base,\n+                    Some(&bearer),\n+                    vec![RpcCommand::RoomCreate { slug }],\n+                )\n+                .await?;\n+                match rpc_line_ok(&batch.results[0])? {\n+                    RpcResult::RoomCreated { room_id } => {\n+                        if json {\n+                            println!(\n+                                \"{}\",\n+                                serde_json::to_string_pretty(&serde_json::json!({\n+                                    \"ok\": true,\n+                                    \"room_id\": room_id,\n+                                }))?\n+                            );\n+                        } else {\n+                            println!(\"{room_id}\");\n+                            println!();\n+                            println!(\"Next: npx slugsocial private {room_id} forum post <TAG> --delegate '…' …\");\n+                            println!(\"      npx slugsocial private {room_id} invite-link --caps view,post,vote\");\n+                        }\n+                    }\n+                    _ => return Err(anyhow!(\"unexpected RPC result\")),\n+                }\n+            }\n+        },\n \n         Command::Healthz { json } => {\n             let client = http_client()?;\ndiff --git a/server/src/api/rpc.rs b/server/src/api/rpc.rs\nindex f6bbc3df71909a2da7403cd46fe4ea6ca130c692..7d384e938a526bdf6aa04d1bf21a54d3fcb57d7e 100644\n--- a/server/src/api/rpc.rs\n+++ b/server/src/api/rpc.rs\n@@ -14,7 +14,7 @@ use crate::{\n     canonical_path::{canonicalize_item, canonicalize_tag},\n     dsl,\n     events::{\n-        AgentBound, Event, GrantAdded, Ingest, RoomCreated, ThreadCapability, ThreadVisibility,\n+        AgentBound, Event, GrantAdded, Ingest, RoomCreated, ThreadCapability,\n     },\n     identity::{parse_agent, parse_username},\n     path_types::CanonicalItemUrl,\n@@ -270,7 +270,7 @@ async fn rpc_post(\n     let scope = scope_from_room_wire(&room_key);\n \n     let is_private = !matches!(scope, ScopeId::Public);\n-    if is_private && !reduced.rooms.contains_key(&room_key) {\n+    if is_private && !reduced.rooms.contains(&room_key) {\n         drop(reduced);\n         return Err((\"unknown room\".into(), Some(format!(\"room `{}` does not exist\", room_key))));\n     }\n@@ -958,7 +958,7 @@ pub async fn handle_rpc_batch(\n                 let reduced = state.reduced.read().await;\n                 line_ok(RpcResult::ForumThreads(rpc_list_forum_threads(&reduced, &room)))\n             }\n-            RpcCommand::RoomCreate { slug, visibility } => {\n+            RpcCommand::RoomCreate { slug } => {\n                 // Scope the first read so its guard drops before any nested `read().await` / `write().await`.\n                 // A guard from `match verify(..., &*state.reduced.read().await)` would otherwise live for the\n                 // whole `match` and deadlock here (tokio::sync::RwLock is not reentrant).\n@@ -975,53 +975,42 @@ pub async fn handle_rpc_batch(\n                         } else if !slug.chars().all(|c| c.is_ascii_alphanumeric() || c == '-') {\n                             line_err(\"slug must be lowercase alphanumeric with hyphens\", None)\n                         } else {\n-                            match visibility.as_deref().unwrap_or(\"private\") {\n-                                \"private\" | \"public\" => {\n-                                    let vis = if visibility.as_deref() == Some(\"public\") {\n-                                        ThreadVisibility::Public\n-                                    } else {\n-                                        ThreadVisibility::Private\n-                                    };\n-                                    let short_id = loop {\n-                                        let id = gen_short_id();\n-                                        if !state.reduced.read().await.rooms.contains_key(&format!(\"{id}/{slug}\")) {\n-                                            break id;\n-                                        }\n-                                    };\n-                                    let room_id = format!(\"{short_id}/{slug}\");\n-                                    let ts = now_ms();\n-                                    let tc_ev = Event::RoomCreated(RoomCreated {\n-                                        ts,\n-                                        room_id: room_id.clone(),\n-                                        slug: slug.clone(),\n-                                        owner: principal.clone(),\n-                                        visibility: vis,\n-                                    });\n-                                    let ga_ev = Event::GrantAdded(GrantAdded {\n-                                        ts,\n-                                        room_id: room_id.clone(),\n-                                        username: principal.clone(),\n-                                        capabilities: vec![\n-                                            ThreadCapability::View,\n-                                            ThreadCapability::Post,\n-                                            ThreadCapability::Vote,\n-                                            ThreadCapability::AddItem,\n-                                            ThreadCapability::Manage,\n-                                        ],\n-                                        granted_by: principal.clone(),\n-                                    });\n-                                    if let Err(e) = state.event_log.append(&tc_ev).await {\n-                                        line_err(format!(\"{e}\"), None)\n-                                    } else if let Err(e) = state.event_log.append(&ga_ev).await {\n-                                        line_err(format!(\"{e}\"), None)\n-                                    } else {\n-                                        let mut r = state.reduced.write().await;\n-                                        r.apply_event(tc_ev);\n-                                        r.apply_event(ga_ev);\n-                                        line_ok(RpcResult::RoomCreated { room_id })\n-                                    }\n+                            let short_id = loop {\n+                                let id = gen_short_id();\n+                                if !state.reduced.read().await.rooms.contains(&format!(\"{id}/{slug}\")) {\n+                                    break id;\n                                 }\n-                                other => line_err(format!(\"unknown visibility: {other}\"), None),\n+                            };\n+                            let room_id = format!(\"{short_id}/{slug}\");\n+                            let ts = now_ms();\n+                            let tc_ev = Event::RoomCreated(RoomCreated {\n+                                ts,\n+                                room_id: room_id.clone(),\n+                                slug: slug.clone(),\n+                                owner: principal.clone(),\n+                            });\n+                            let ga_ev = Event::GrantAdded(GrantAdded {\n+                                ts,\n+                                room_id: room_id.clone(),\n+                                username: principal.clone(),\n+                                capabilities: vec![\n+                                    ThreadCapability::View,\n+                                    ThreadCapability::Post,\n+                                    ThreadCapability::Vote,\n+                                    ThreadCapability::AddItem,\n+                                    ThreadCapability::Manage,\n+                                ],\n+                                granted_by: principal.clone(),\n+                            });\n+                            if let Err(e) = state.event_log.append(&tc_ev).await {\n+                                line_err(format!(\"{e}\"), None)\n+                            } else if let Err(e) = state.event_log.append(&ga_ev).await {\n+                                line_err(format!(\"{e}\"), None)\n+                            } else {\n+                                let mut r = state.reduced.write().await;\n+                                r.apply_event(tc_ev);\n+                                r.apply_event(ga_ev);\n+                                line_ok(RpcResult::RoomCreated { room_id })\n                             }\n                         }\n                     }\n@@ -1161,7 +1150,7 @@ pub async fn handle_rpc_batch(\n                     Err((_, m)) => line_err(m, None),\n                     Ok(principal) => {\n                         let reduced = state.reduced.read().await;\n-                        if !reduced.rooms.contains_key(&room) {\n+                        if !reduced.rooms.contains(&room) {\n                             line_err(\"unknown room\", None)\n                         } else {\n                             let can_audit = reduced.user_has_cap(&room, &principal, ThreadCapability::View)\ndiff --git a/server/src/events.rs b/server/src/events.rs\nindex 9e60f2c218f5c871a93e855e415dd984e3a017c5..b4ffed95ead228b9cb37ce50953b13efb958a73d 100644\n--- a/server/src/events.rs\n+++ b/server/src/events.rs\n@@ -1,12 +1,5 @@\n use serde::{Deserialize, Serialize};\n \n-#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]\n-#[serde(rename_all = \"snake_case\")]\n-pub enum ThreadVisibility {\n-    Public,\n-    Private,\n-}\n-\n #[derive(Debug, Clone, Copy, Hash, Serialize, Deserialize, PartialEq, Eq)]\n #[serde(rename_all = \"snake_case\")]\n pub enum ThreadCapability {\n@@ -57,13 +50,13 @@ pub struct AgentBound {\n     pub username: String,\n }\n \n+/// Private space keyed as `shortid/slug`.\n #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]\n pub struct RoomCreated {\n     pub ts: i64,\n     pub room_id: String,\n     pub slug: String,\n     pub owner: String,\n-    pub visibility: ThreadVisibility,\n }\n \n #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]\ndiff --git a/server/src/html/search.rs b/server/src/html/search.rs\nindex 9353cf229fbbd2cfbab5b89ba63ebe192042c91f..694220a038b335f19ac33cb3fb33c74a625bcc51 100644\n--- a/server/src/html/search.rs\n+++ b/server/src/html/search.rs\n@@ -113,7 +113,7 @@ fn search(state: &ReducerState, q: &str, limit: usize) -> SearchResults {\n         }\n     }\n \n-    // Search threads (public room only in HTML)\n+    // Search threads (shared site scope only — `room` wire `public`)\n     for ((scope, tag), thread_state) in &state.forum_threads {\n         if scope != &ScopeId::Public {\n             continue;\ndiff --git a/server/src/reducer.rs b/server/src/reducer.rs\nindex 5190d0a7ee3d545a786a68fef483322aafdce7f9..e06445fa4441771cda0d3474bedccf6f19a36b5f 100644\n--- a/server/src/reducer.rs\n+++ b/server/src/reducer.rs\n@@ -3,7 +3,7 @@ use std::collections::{HashMap, HashSet, VecDeque};\n use serde::{Deserialize, Serialize};\n \n use crate::canonical_path::canonicalize_tag;\n-use crate::events::{Event, Ingest, ThreadCapability, ThreadVisibility};\n+use crate::events::{Event, Ingest, ThreadCapability};\n use crate::path_types::CanonicalItemUrl;\n \n #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]\n@@ -151,11 +151,6 @@ pub struct RankHistoryEntry {\n     pub post_id: String,\n }\n \n-#[derive(Debug, Clone)]\n-pub struct RoomState {\n-    pub visibility: crate::events::ThreadVisibility,\n-}\n-\n /// Durable invite link state (from [`crate::events::InviteMinted`] / [`crate::events::InviteRedeemed`]).\n #[derive(Debug, Clone)]\n pub struct ActiveInviteState {\n@@ -171,7 +166,6 @@ pub enum RoomTimelineKind {\n     RoomCreated {\n         owner: String,\n         slug: String,\n-        visibility: ThreadVisibility,\n     },\n     GrantAdded {\n         username: String,\n@@ -235,8 +229,8 @@ pub struct ReducerState {\n     pub ingests_by_id: HashMap<String, Ingest>,\n     /// (scope, thread_tag) → ingest ids, newest first.\n     pub ingests_by_scope_thread: HashMap<(ScopeId, String), VecDeque<String>>,\n-    /// Private (or public) room registry: room_id → visibility from [`RoomCreated`].\n-    pub rooms: HashMap<String, RoomState>,\n+    /// Private room ids (`shortid/slug`) known from [`RoomCreated`].\n+    pub rooms: HashSet<String>,\n     /// (scope, thread_tag) → last activity.\n     pub forum_threads: HashMap<(ScopeId, String), ForumThreadState>,\n     pub actor_last_post_ts: HashMap<String, i64>,\n@@ -403,12 +397,7 @@ impl ReducerState {\n                 self.agent_bindings.insert(ab.agent, ab.username);\n             }\n             Event::RoomCreated(rc) => {\n-                self.rooms.insert(\n-                    rc.room_id.clone(),\n-                    RoomState {\n-                        visibility: rc.visibility,\n-                    },\n-                );\n+                self.rooms.insert(rc.room_id.clone());\n                 self.room_timeline\n                     .entry(rc.room_id.clone())\n                     .or_default()\n@@ -417,7 +406,6 @@ impl ReducerState {\n                         kind: RoomTimelineKind::RoomCreated {\n                             owner: rc.owner.clone(),\n                             slug: rc.slug.clone(),\n-                            visibility: rc.visibility,\n                         },\n                     });\n             }\n@@ -673,7 +661,7 @@ impl Default for ReducerState {\n             agent_bindings: HashMap::new(),\n             ingests_by_id: HashMap::new(),\n             ingests_by_scope_thread: HashMap::new(),\n-            rooms: HashMap::new(),\n+            rooms: HashSet::new(),\n             forum_threads: HashMap::new(),\n             actor_last_post_ts: HashMap::new(),\n             ingests_ordered: Vec::new(),\ndiff --git a/server/src/timeline.rs b/server/src/timeline.rs\nindex 251158943ab36d3015268e35f6bdd01c3f42ab3b..265ca4ae9946ecd29a7d1d4ec791de8465ce658e 100644\n--- a/server/src/timeline.rs\n+++ b/server/src/timeline.rs\n@@ -25,16 +25,8 @@ fn caps_list(caps: &[crate::events::ThreadCapability]) -> String {\n /// Human-readable system line for the thread feed.\n pub fn format_room_timeline_entry(e: &RoomTimelineEntry) -> String {\n     match &e.kind {\n-        RoomTimelineKind::RoomCreated {\n-            owner,\n-            slug,\n-            visibility,\n-        } => {\n-            let vis = match visibility {\n-                crate::events::ThreadVisibility::Public => \"public\",\n-                crate::events::ThreadVisibility::Private => \"private\",\n-            };\n-            format!(\"@{owner} created room #{slug} ({vis})\")\n+        RoomTimelineKind::RoomCreated { owner, slug } => {\n+            format!(\"@{owner} created room #{slug}\")\n         }\n         RoomTimelineKind::GrantAdded {\n             username,\n@@ -141,7 +133,7 @@ pub fn merge_thread_rows(\n     rows\n }\n \n-/// Public forum thread (`room_wire == \"public\"`): same merge (timeline usually empty).\n+/// Shared-site thread view (`room_wire == \"public\"` on the wire). Same merge as private rooms; private-room timeline is unused here.\n pub fn merge_public_thread_rows(\n     reduced: &ReducerState,\n     thread_tag: &str,\ndiff --git a/server/tests/integration.rs b/server/tests/integration.rs\nindex b930120da09fe7d307f0411b84fb639fb8bd0b15..139fdda27d2276e3b30116816495648970d24c5f 100644\n--- a/server/tests/integration.rs\n+++ b/server/tests/integration.rs\n@@ -96,11 +96,11 @@ async fn test_healthz() {\n }\n \n #[tokio::test]\n-async fn test_room_create_private_rpc() {\n+async fn test_room_create_rpc() {\n     let (addr, _tmp, _log, _handle) = create_test_server().await;\n     let client = reqwest::Client::new();\n     let batch = serde_json::json!([{\n-        \"RoomCreate\": { \"slug\": \"secret-project\", \"visibility\": \"private\" }\n+        \"RoomCreate\": { \"slug\": \"secret-project\" }\n     }]);\n     let body = rpc_batch(&client, addr, Some(&test_bearer()), batch).await;\n     let line = &body[\"results\"][0];\ndiff --git a/test/grants.bb b/test/grants.bb\nindex 4ded5ce92576cdea653cce0ba8a751be4374731a..697e7d91545dd3ee96efde07fc8c3cf90f1a8056 100644\n--- a/test/grants.bb\n+++ b/test/grants.bb\n@@ -82,7 +82,7 @@\n            ;; Alice creates a private room.\n            _ (println \"\\nalice creates private room…\")\n            create (rpc-batch! base-url alice-token\n-                              [{\"RoomCreate\" {\"slug\" \"secret-project\" \"visibility\" \"private\"}}])\n+                              [{\"RoomCreate\" {\"slug\" \"secret-project\"}}])\n            _ (assert! (= 200 (:status create)) \"room create HTTP 200\")\n            _ (assert! (rpc-line-ok? (:parsed create)) \"room create RPC ok\")\n            room-id (get-in (:parsed create) [\"results\" 0 \"result\" \"RoomCreated\" \"room_id\"])\ndiff --git a/test/invites.bb b/test/invites.bb\nindex f72b1e630a6856174cdef11eb977e2f81b16e551..ca0fd6c858400671452c4ec59c490d05101dd0e4 100644\n--- a/test/invites.bb\n+++ b/test/invites.bb\n@@ -86,7 +86,7 @@\n \n            _ (println \"\\nalice creates private room…\")\n            create (rpc-batch! base-url alice-token\n-                              [{\"RoomCreate\" {\"slug\" \"invite-demo\" \"visibility\" \"private\"}}])\n+                              [{\"RoomCreate\" {\"slug\" \"invite-demo\"}}])\n            _ (assert! (= 200 (:status create)) \"room create HTTP 200\")\n            _ (assert! (rpc-line-ok? (:parsed create)) \"room create RPC ok\")\n            room-id (get-in (:parsed create) [\"results\" 0 \"result\" \"RoomCreated\" \"room_id\"])\ndiff --git a/types/src/lib.rs b/types/src/lib.rs\nindex 98c66a00fd27803ef6f75b5ac478ff2eb762d771..bb8586f1734f77d95598a9294bdb0de2d55bf715 100644\n--- a/types/src/lib.rs\n+++ b/types/src/lib.rs\n@@ -319,8 +319,6 @@ pub enum RpcCommand {\n     },\n     RoomCreate {\n         slug: String,\n-        #[serde(default, skip_serializing_if = \"Option::is_none\")]\n-        visibility: Option<String>,\n     },\n     RoomGrant {\n         room: String,\n\n\nSide B — contributor: tommy-mor\nSide B — commit message:\n[88577c56] reconfigure\n\nSide B — unified diff (full patch):\ndiff --git a/server/src/api/ui_html.rs b/server/src/api/ui_html.rs\nindex c4ab9d65c7b3cd42a5b4d093ba429993c101e9a8..82b2aa51d21ada1d0d849d3ddfc3a81e4241d861 100644\n--- a/server/src/api/ui_html.rs\n+++ b/server/src/api/ui_html.rs\n@@ -9,7 +9,9 @@ use crate::{\n     html::{js_string_literal, ranking_panel, JsBuilder},\n     parser::parse_reddit_url,\n     parser_render::navigate_panel,\n-    state::AppState,\n+    path_types::ItemId,\n+    reddit::ensure_partial_tree,\n+    state::{parse_item_param, AppState},\n     ui_action::{parse_html_ui_from_form, HtmlUiAction},\n };\n \n@@ -25,6 +27,10 @@ fn ui_js_warn(msg: &str) -> Response {\n         .unwrap()\n }\n \n+fn parent_from_scope(scope: &str) -> ItemId {\n+    parse_item_param(scope)\n+}\n+\n pub async fn post_ui_html(\n     State(state): State<AppState>,\n     Form(form): Form<HashMap<String, String>>,\n@@ -42,24 +48,36 @@ pub async fn post_ui_html(\n             ratio_right,\n             scope,\n         } => {\n+            let parent = parent_from_scope(&scope);\n             if let Err(e) = state\n-                .record_vote(&scope, &a, &b, ratio_left, ratio_right)\n+                .record_vote(&parent, &a, &b, ratio_left, ratio_right)\n                 .await\n             {\n                 return ui_js_warn(&e).into_response();\n             }\n-            let scope = crate::state::normalize_scope(&scope);\n-            let groups = state.groups.read().await;\n+            let tree = state.tree.read().await;\n             let empty = crate::reducer::GroupState::new();\n-            let group = groups.get(&scope).unwrap_or(&empty);\n-            let panel = ranking_panel(&scope, group);\n+            let group = tree\n+                .get(&parent)\n+                .map(|n| &n.local_ranking)\n+                .unwrap_or(&empty);\n+            let panel = ranking_panel(&parent, group);\n             JsBuilder::new()\n                 .morph_selector(\"#ranking-panel\", panel)\n                 .into_response()\n         }\n         HtmlUiAction::ParseQuery { query } => match parse_reddit_url(&query) {\n-            Ok(subreddit) => {\n-                let dest = format!(\"/?sub={subreddit}\");\n+            Ok(item) => {\n+                {\n+                    let mut tree = state.tree.write().await;\n+                    ensure_partial_tree(&mut tree, &item);\n+                }\n+                let _ = state.ensure_node(&item).await;\n+                let dest = if item.is_root() {\n+                    \"/\".to_string()\n+                } else {\n+                    format!(\"/?item={}\", item.as_str())\n+                };\n                 JsBuilder::new()\n                     .raw(&format!(\n                         \"window.location.href={};\",\ndiff --git a/server/src/events.rs b/server/src/events.rs\nindex a862370fc840ffe02184a11c578e18239cc9474d..ed5be6b13b9d46e838831d6ce0f96f569b401730 100644\n--- a/server/src/events.rs\n+++ b/server/src/events.rs\n@@ -5,8 +5,8 @@ use serde::{Deserialize, Serialize};\n pub enum Event {\n     /// Page view recorded (path → counter in views.json).\n     ViewRecorded { path: String, ts: i64 },\n-    /// Pairwise comparison vote (replayed into the scope's [`crate::reducer::GroupState`] on boot).\n-    /// `scope` is the ranking subject (e.g. a subreddit); empty string is the default/global scope.\n+    /// Pairwise comparison vote (replayed into the parent node's [`crate::reducer::GroupState`] on boot).\n+    /// `scope` is the parent [`crate::path_types::ItemId`] string; empty string is the tree root.\n     VoteRecorded {\n         ts: i64,\n         a: String,\n@@ -16,4 +16,6 @@ pub enum Event {\n         #[serde(default)]\n         scope: String,\n     },\n+    /// Register a node path in the fractal tree (no external fetch).\n+    NodeEnsured { id: String },\n }\ndiff --git a/server/src/html/mod.rs b/server/src/html/mod.rs\nindex 9650d333d29c4ac94ceb407aee3ee00399c7f40b..c973cb718ac74b95570dabea76e24459417790b9 100644\n--- a/server/src/html/mod.rs\n+++ b/server/src/html/mod.rs\n@@ -12,9 +12,10 @@ use serde::Deserialize;\n use crate::{\n     form_template::template_json_compact,\n     parser_render::navigate_panel,\n+    path_types::ItemId,\n     ranking::{top_bottom, RankedItem},\n-    reducer::GroupState,\n-    state::{normalize_scope, AppState},\n+    reducer::{GroupState, NodeState},\n+    state::{parse_item_param, AppState},\n     ui_action::UI_RPC_FIELD,\n };\n \n@@ -216,6 +217,48 @@ fn layout(title: &str, body: Markup, views: u64, theme: &str, theme_next: &str)\n     }\n }\n \n+fn item_href(id: &ItemId) -> String {\n+    if id.is_root() {\n+        \"/\".to_string()\n+    } else {\n+        format!(\"/?item={}\", id.as_str())\n+    }\n+}\n+\n+fn segment_label(seg: &str) -> &str {\n+    seg\n+}\n+\n+/// Generic breadcrumb trail from an [`ItemId`] path.\n+pub fn breadcrumb_path(item: &ItemId) -> Markup {\n+    html! {\n+        nav class=\"breadcrumbs\" aria-label=\"Breadcrumb\" {\n+            a href=\"/\" { \"Internet\" }\n+            @for path in item.breadcrumb_paths() {\n+                @let seg = path.segments().last().map_or(\"\", |v| *v);\n+                span class=\"separator\" { \" / \" }\n+                a href=(item_href(&path)) { (segment_label(seg)) }\n+            }\n+        }\n+    }\n+}\n+\n+fn entity_panel(node: &NodeState) -> Markup {\n+    html! {\n+        @if let Some(data) = &node.data {\n+            section id=\"entity-panel\" class=\"demo-panel entity-card\" {\n+                h2 { (data.title) }\n+                @if let Some(author) = &data.author {\n+                    p class=\"muted small\" { \"by \" (author) }\n+                }\n+                @if let Some(body) = &data.body_html {\n+                    div class=\"entity-body\" { (maud::PreEscaped(body)) }\n+                }\n+            }\n+        }\n+    }\n+}\n+\n fn rank_list(label: &str, items: &[RankedItem], start_rank: usize) -> Markup {\n     html! {\n         @if !items.is_empty() {\n@@ -224,7 +267,9 @@ fn rank_list(label: &str, items: &[RankedItem], start_rank: usize) -> Markup {\n                 @for (i, r) in items.iter().enumerate() {\n                     li {\n                         span class=\"rank-num\" { (start_rank + i) \". \" }\n-                        strong { (r.item.as_str()) }\n+                        a href=(item_href(&r.item)) {\n+                            strong { (display_label(&r.item)) }\n+                        }\n                         span class=\"muted\" {\n                             \" — \"\n                             ({ format!(\"{:.1}%\", r.score * 100.0) })\n@@ -236,23 +281,30 @@ fn rank_list(label: &str, items: &[RankedItem], start_rank: usize) -> Markup {\n     }\n }\n \n-pub fn ranking_panel(scope: &str, group: &GroupState) -> Markup {\n+fn display_label(id: &ItemId) -> String {\n+    id.segments()\n+        .last()\n+        .map_or(\"Internet\", |v| *v)\n+        .to_string()\n+}\n+\n+pub fn ranking_panel(item: &ItemId, group: &GroupState) -> Markup {\n     let total = group.idx_to_item.len();\n     let (top, bottom) = top_bottom(group, 8);\n     html! {\n         section id=\"ranking-panel\" class=\"demo-panel\" {\n             h2 {\n                 \"Ranking\"\n-                @if !scope.is_empty() {\n-                    \" — \" span class=\"scope-name\" { \"r/\" (scope) }\n+                @if !item.is_root() {\n+                    \" — \" span class=\"scope-name\" { (item.as_str()) }\n                 }\n             }\n             @if total == 0 {\n                 p class=\"muted\" {\n-                    @if scope.is_empty() {\n+                    @if item.is_root() {\n                         \"No votes yet — compare two items below.\"\n                     } @else {\n-                        \"No votes yet for r/\" (scope) \" — compare two items below to start the ranking.\"\n+                        \"No votes yet for \" (item.as_str()) \" — compare two items below to start the ranking.\"\n                     }\n                 }\n             } @else {\n@@ -266,7 +318,8 @@ pub fn ranking_panel(scope: &str, group: &GroupState) -> Markup {\n     }\n }\n \n-pub fn vote_panel(scope: &str) -> Markup {\n+pub fn vote_panel(parent: &ItemId) -> Markup {\n+    let parent_str = parent.as_str();\n     let rpc = template_json_compact(&serde_json::json!({\n         \"action\": \"record_vote\",\n         \"a\": {\"$form\": \"item_a\"},\n@@ -280,16 +333,17 @@ pub fn vote_panel(scope: &str) -> Markup {\n         section id=\"vote-panel\" class=\"demo-panel\" {\n             h2 { \"Compare\" }\n             p class=\"muted small\" {\n-                @if scope.is_empty() {\n+                @if parent.is_root() {\n                     \"Left item wins at 2:1. Votes append to the JSONL log and update rank centrality.\"\n                 } @else {\n-                    \"Ranking \" span class=\"scope-name\" { \"r/\" (scope) }\n+                    \"Ranking children of \"\n+                    span class=\"scope-name\" { (parent_str) }\n                     \". Left item wins at 2:1; each vote updates this ranking.\"\n                 }\n             }\n             form method=\"post\" action=\"/ui\" id=\"vote-form\" {\n                 input type=\"hidden\" name=(UI_RPC_FIELD) value=(rpc);\n-                input type=\"hidden\" name=\"scope\" value=(scope);\n+                input type=\"hidden\" name=\"scope\" value=(parent_str);\n                 div class=\"vote-fields\" {\n                     label {\n                         \"Left (wins) \"\n@@ -329,17 +383,30 @@ pub async fn home(\n     let views = state.views.get_views(&path);\n     let theme = theme_from_jar(&jar);\n     let theme_next = theme_next_from_uri(&uri);\n-    let scope = normalize_scope(&query_param(&uri, \"sub\").unwrap_or_default());\n \n-    let groups = state.groups.read().await;\n-    let empty = GroupState::new();\n-    let group = groups.get(&scope).unwrap_or(&empty);\n+    let item_raw = query_param(&uri, \"item\")\n+        .or_else(|| query_param(&uri, \"sub\").map(|sub| {\n+            if sub.is_empty() {\n+                String::new()\n+            } else {\n+                format!(\"reddit.com/r/{sub}\")\n+            }\n+        }))\n+        .unwrap_or_default();\n+    let item = parse_item_param(&item_raw);\n+\n+    let tree = state.tree.read().await;\n+    let empty_node = NodeState::default();\n+    let node = tree.get(&item).unwrap_or(&empty_node);\n+    let group = &node.local_ranking;\n \n     let body = html! {\n         h1 { \"sorter2\" }\n+        (breadcrumb_path(&item))\n         (navigate_panel(\"\", None))\n-        (vote_panel(&scope))\n-        (ranking_panel(&scope, group))\n+        (entity_panel(node))\n+        (vote_panel(&item))\n+        (ranking_panel(&item, group))\n     };\n     layout(\"sorter2\", body, views, theme, &theme_next)\n }\ndiff --git a/server/src/journal.rs b/server/src/journal.rs\nnew file mode 100644\nindex 0000000000000000000000000000000000000000..b02ca025683621470ffdf8cd85cf9b85c56d024d\n--- /dev/null\n+++ b/server/src/journal.rs\n@@ -0,0 +1,89 @@\n+use std::sync::Arc;\n+\n+use tokio::sync::{mpsc, oneshot, RwLock};\n+\n+use crate::{\n+    event_log::EventLog,\n+    events::Event,\n+    path_types::ItemId,\n+    reducer::{GlobalTree, VoteData},\n+};\n+\n+pub struct JournalCommand {\n+    pub parent: ItemId,\n+    pub vote: VoteData,\n+    pub event: Event,\n+    pub reply: oneshot::Sender<Result<(), String>>,\n+}\n+\n+#[derive(Clone)]\n+pub struct JournalClient {\n+    tx: mpsc::Sender<JournalCommand>,\n+}\n+\n+impl JournalClient {\n+    pub fn spawn(tree: Arc<RwLock<GlobalTree>>, event_log: Arc<EventLog>) -> Self {\n+        let (tx, rx) = mpsc::channel(64);\n+        tokio::spawn(journal_worker(rx, tree, event_log));\n+        Self { tx }\n+    }\n+\n+    pub async fn record_vote(\n+        &self,\n+        parent: ItemId,\n+        vote: VoteData,\n+        event: Event,\n+    ) -> Result<(), String> {\n+        let (reply, rx) = oneshot::channel();\n+        self.tx\n+            .send(JournalCommand {\n+                parent,\n+                vote,\n+                event,\n+                reply,\n+            })\n+            .await\n+            .map_err(|_| \"journal worker stopped\".to_string())?;\n+        rx.await\n+            .map_err(|_| \"journal worker stopped\".to_string())?\n+    }\n+}\n+\n+async fn journal_worker(\n+    mut rx: mpsc::Receiver<JournalCommand>,\n+    tree: Arc<RwLock<GlobalTree>>,\n+    event_log: Arc<EventLog>,\n+) {\n+    while let Some(first) = rx.recv().await {\n+        let mut batch = vec![first];\n+        while let Ok(more) = rx.try_recv() {\n+            batch.push(more);\n+        }\n+\n+        let mut disk_err: Option<String> = None;\n+        for cmd in &batch {\n+            if let Err(e) = event_log.append(&cmd.event).await {\n+                disk_err = Some(e.to_string());\n+                break;\n+            }\n+        }\n+\n+        if let Some(err) = disk_err {\n+            for cmd in batch {\n+                let _ = cmd.reply.send(Err(err.clone()));\n+            }\n+            continue;\n+        }\n+\n+        {\n+            let mut w = tree.write().await;\n+            for cmd in &batch {\n+                w.apply_vote(&cmd.parent, cmd.vote.clone());\n+            }\n+        }\n+\n+        for cmd in batch {\n+            let _ = cmd.reply.send(Ok(()));\n+        }\n+    }\n+}\ndiff --git a/server/src/lib.rs b/server/src/lib.rs\nindex de8bca48cbf689cad22337883e7791966e7c4919..14e7cfbc38feb5d07aff859b64bce6e2ec45cf91 100644\n--- a/server/src/lib.rs\n+++ b/server/src/lib.rs\n@@ -7,8 +7,9 @@ pub mod parser;\n pub mod parser_render;\n pub mod path_types;\n pub mod ranking;\n+pub mod reddit;\n pub mod reducer;\n-pub mod settlement;\n+pub mod journal;\n pub mod state;\n pub mod ui_action;\n pub mod views;\ndiff --git a/server/src/parser.rs b/server/src/parser.rs\nindex 50571a59f0d3ece1e2538f88e00ef46ec40ea545..51aa0e0f982546aab68bd5e1ca0cb726e88b3f50 100644\n--- a/server/src/parser.rs\n+++ b/server/src/parser.rs\n@@ -1,47 +1,18 @@\n-//! Extract a subreddit name from a pasted Reddit URL or path.\n+//! Extract a canonical [`crate::path_types::ItemId`] from a pasted Reddit URL or path.\n \n-pub fn parse_reddit_url(query: &str) -> Result<String, String> {\n+use crate::path_types::ItemId;\n+\n+pub fn parse_reddit_url(query: &str) -> Result<ItemId, String> {\n     let q = query.trim();\n     if q.is_empty() {\n         return Err(\"Paste a Reddit URL or r/subreddit path\".into());\n     }\n \n-    if let Some(sub) = subreddit_after_prefix(q, \"r/\") {\n-        return Ok(sub);\n-    }\n-\n-    if let Some(sub) = subreddit_from_path_segment(q, \"/r/\") {\n-        return Ok(sub);\n+    if let Some(id) = ItemId::from_url(q) {\n+        return Ok(id);\n     }\n \n-    Err(\"Could not find a subreddit in that URL\".into())\n-}\n-\n-fn subreddit_after_prefix(text: &str, prefix: &str) -> Option<String> {\n-    let rest = text.strip_prefix(prefix)?;\n-    let sub = rest.split(['/', '?', '#']).next()?.trim();\n-    valid_subreddit(sub)\n-}\n-\n-fn subreddit_from_path_segment(text: &str, needle: &str) -> Option<String> {\n-    let idx = text.find(needle)?;\n-    let rest = &text[idx + needle.len()..];\n-    let sub = rest.split(['/', '?', '#']).next()?.trim();\n-    valid_subreddit(sub)\n-}\n-\n-fn valid_subreddit(name: &str) -> Option<String> {\n-    if name.is_empty() {\n-        return None;\n-    }\n-    if name\n-        .chars()\n-        .all(|c| c.is_ascii_alphanumeric() || c == '_')\n-    {\n-        Some(name.to_ascii_lowercase())\n-    } else {\n-        None\n-    }\n+    Err(\"Could not parse that Reddit URL\".into())\n }\n \n #[cfg(test)]\n@@ -50,34 +21,37 @@ mod tests {\n \n     #[test]\n     fn parses_short_path() {\n-        assert_eq!(parse_reddit_url(\"r/rust\").unwrap(), \"rust\");\n-    }\n-\n-    #[test]\n-    fn parses_path_with_trailing_slash() {\n-        assert_eq!(parse_reddit_url(\"r/rust/\").unwrap(), \"rust\");\n+        assert_eq!(\n+            parse_reddit_url(\"r/rust\").unwrap().as_str(),\n+            \"reddit.com/r/rust\"\n+        );\n     }\n \n     #[test]\n     fn parses_full_url() {\n         assert_eq!(\n-            parse_reddit_url(\"https://www.reddit.com/r/programming/hot\").unwrap(),\n-            \"programming\"\n+            parse_reddit_url(\"https://www.reddit.com/r/programming/hot\")\n+                .unwrap()\n+                .as_str(),\n+            \"reddit.com/r/programming\"\n         );\n     }\n \n     #[test]\n-    fn parses_url_without_scheme() {\n+    fn parses_post_url() {\n+        let id = parse_reddit_url(\n+            \"https://old.reddit.com/r/AmItheAsshole/comments/1trnvdl/aita_for_cancelling/\",\n+        )\n+        .unwrap();\n         assert_eq!(\n-            parse_reddit_url(\"reddit.com/r/AskReddit\").unwrap(),\n-            \"askreddit\"\n+            id.as_str(),\n+            \"reddit.com/r/amitheasshole/comments/1trnvdl\"\n         );\n     }\n \n     #[test]\n     fn rejects_empty() {\n         assert!(parse_reddit_url(\"\").is_err());\n-        assert!(parse_reddit_url(\"   \").is_err());\n     }\n \n     #[test]\ndiff --git a/server/src/parser_render.rs b/server/src/parser_render.rs\nindex f2341afe21476b689a536137798d97277211a962..acf2e7403f4238291677ef0c79d5766302ea78cf 100644\n--- a/server/src/parser_render.rs\n+++ b/server/src/parser_render.rs\n@@ -21,7 +21,7 @@ pub fn navigate_panel(query: &str, error: Option<&str>) -> Markup {\n             p class=\"muted small\" {\n                 \"Paste a Reddit URL or \"\n                 code { \"r/subreddit\" }\n-                \" path, then click Go to rank that subreddit.\"\n+                \" path. Breadcrumb links drill down the tree; rankings apply to each node's children.\"\n             }\n             form method=\"post\" action=\"/ui\" id=\"parser-form\" {\n                 textarea\ndiff --git a/server/src/path_types.rs b/server/src/path_types.rs\nindex 1cdc96a25b1954f11aaf955203e2b9907b578366..b5c41444f7bcd4d8d289ed3af464bc3f14d0df99 100644\n--- a/server/src/path_types.rs\n+++ b/server/src/path_types.rs\n@@ -1,11 +1,13 @@\n use serde::{Deserialize, Serialize};\n use std::fmt;\n \n-/// Stable item key for votes and rankings (opaque string for now).\n-#[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]\n+/// Canonical hierarchical identity for any URL/path in the fractal tree.\n+#[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize, Default)]\n pub struct ItemId(String);\n \n impl ItemId {\n+    /// Parse an already-canonical path (no URL normalization). Empty string is invalid here;\n+    /// use [`Self::root`] for the tree root.\n     pub fn parse(s: &str) -> Option<Self> {\n         let t = s.trim();\n         if t.is_empty() {\n@@ -14,13 +16,170 @@ impl ItemId {\n         Some(Self(t.to_string()))\n     }\n \n+    /// Build an opaque item key (legacy demo votes, non-URL items).\n     pub fn opaque(s: impl Into<String>) -> Self {\n         Self(s.into())\n     }\n \n+    /// Root of the internet tree (empty path).\n+    pub fn root() -> Self {\n+        Self(String::new())\n+    }\n+\n+    pub fn is_root(&self) -> bool {\n+        self.0.is_empty()\n+    }\n+\n     pub fn as_str(&self) -> &str {\n         &self.0\n     }\n+\n+    /// Creates a canonical ID from a raw URL or path. Normalizes domains and\n+    /// trims tracking query params.\n+    pub fn from_url(raw_url: &str) -> Option<Self> {\n+        Self::canonicalize(raw_url).map(Self)\n+    }\n+\n+    /// Map legacy scope keys (`\"\"`, `\"rust\"`) to fractal parent nodes.\n+    pub fn from_legacy_scope(raw: &str) -> Self {\n+        let s = raw.trim();\n+        if s.is_empty() {\n+            return Self::root();\n+        }\n+        Self(format!(\"reddit.com/r/{s}\"))\n+    }\n+\n+    /// Extract the parent, e.g. `reddit.com/r/aww/comments/1trnvdl` →\n+    /// `reddit.com/r/aww`.\n+    pub fn parent(&self) -> Option<Self> {\n+        if self.0.is_empty() {\n+            return None;\n+        }\n+\n+        let parts: Vec<&str> = self.0.trim_end_matches('/').split('/').collect();\n+        if parts.len() <= 1 {\n+            return None;\n+        }\n+\n+        if self.0.contains(\"/comments/\") {\n+            return Some(Self(parts[..parts.len().saturating_sub(2)].join(\"/\")));\n+        }\n+\n+        Some(Self(parts[..parts.len() - 1].join(\"/\")))\n+    }\n+\n+    pub fn segments(&self) -> Vec<&str> {\n+        self.0.split('/').filter(|s| !s.is_empty()).collect()\n+    }\n+\n+    /// Cumulative paths for breadcrumb rendering, e.g.\n+    /// `reddit.com/r/movies` → `[\"reddit.com\", \"reddit.com/r\", \"reddit.com/r/movies\"]`.\n+    pub fn breadcrumb_paths(&self) -> Vec<ItemId> {\n+        let segs = self.segments();\n+        let mut paths = Vec::with_capacity(segs.len());\n+        let mut current = String::new();\n+        for seg in segs {\n+            if current.is_empty() {\n+                current = seg.to_string();\n+            } else {\n+                current.push('/');\n+                current.push_str(seg);\n+            }\n+            paths.push(ItemId(current.clone()));\n+        }\n+        paths\n+    }\n+\n+    fn canonicalize(raw: &str) -> Option<String> {\n+        let s = raw.trim();\n+        if s.is_empty() {\n+            return None;\n+        }\n+\n+        let owned = if let Some(rest) = s.strip_prefix(\"r/\") {\n+            format!(\"reddit.com/r/{rest}\")\n+        } else if let Some(rest) = s.strip_prefix(\"/r/\") {\n+            format!(\"reddit.com/r/{rest}\")\n+        } else {\n+            s.to_string()\n+        };\n+\n+        let (host_path, _query) = split_query(&owned);\n+        let host_path = host_path.trim_end_matches('/');\n+\n+        let path = if host_path.contains(\"://\") {\n+            parse_url_host_path(host_path)?\n+        } else if host_path.starts_with(\"reddit.com\") || host_path.starts_with(\"www.reddit.com\") {\n+            normalize_reddit_host_path(host_path)\n+        } else if host_path.contains('/') {\n+            host_path.to_string()\n+        } else {\n+            return None;\n+        };\n+\n+        Some(normalize_reddit_path(&path))\n+    }\n+}\n+\n+fn split_query(s: &str) -> (&str, Option<&str>) {\n+    if let Some((path, q)) = s.split_once('?') {\n+        (path, Some(q))\n+    } else {\n+        (s, None)\n+    }\n+}\n+\n+fn parse_url_host_path(url: &str) -> Option<String> {\n+    let rest = url\n+        .strip_prefix(\"https://\")\n+        .or_else(|| url.strip_prefix(\"http://\"))\n+        .unwrap_or(url);\n+    let (host, path) = rest.split_once('/').unwrap_or((rest, \"\"));\n+    let host = normalize_host(host);\n+    if path.is_empty() {\n+        Some(host)\n+    } else {\n+        Some(format!(\"{host}/{path}\"))\n+    }\n+}\n+\n+fn normalize_host(host: &str) -> String {\n+    let h = host\n+        .strip_prefix(\"www.\")\n+        .unwrap_or(host)\n+        .to_ascii_lowercase();\n+    if h == \"old.reddit.com\" || h == \"new.reddit.com\" || h == \"reddit.com\" {\n+        \"reddit.com\".to_string()\n+    } else {\n+        h\n+    }\n+}\n+\n+fn normalize_reddit_host_path(s: &str) -> String {\n+    let (host, path) = s.split_once('/').unwrap_or((s, \"\"));\n+    let host = normalize_host(host);\n+    if path.is_empty() {\n+        host\n+    } else {\n+        format!(\"{host}/{path}\")\n+    }\n+}\n+\n+/// Lowercase subreddit segment, drop listing suffixes, drop title slug after post id.\n+fn normalize_reddit_path(path: &str) -> String {\n+    let mut parts: Vec<String> = path.split('/').map(str::to_string).collect();\n+    if parts.len() >= 3 && parts[1] == \"r\" {\n+        parts[2] = parts[2].to_ascii_lowercase();\n+    }\n+    if let Some(i) = parts.iter().position(|p| p == \"comments\") {\n+        if parts.len() > i + 2 {\n+            parts.truncate(i + 2);\n+        }\n+    } else if parts.len() > 3 && parts.get(1).map(|s| s.as_str()) == Some(\"r\") {\n+        // reddit.com/r/{sub}/hot → reddit.com/r/{sub}\n+        parts.truncate(3);\n+    }\n+    parts.join(\"/\")\n }\n \n impl fmt::Display for ItemId {\n@@ -28,3 +187,69 @@ impl fmt::Display for ItemId {\n         f.write_str(&self.0)\n     }\n }\n+\n+#[cfg(test)]\n+mod tests {\n+    use super::*;\n+\n+    #[test]\n+    fn from_url_normalizes_reddit_domains() {\n+        let id = ItemId::from_url(\n+            \"https://old.reddit.com/r/AmItheAsshole/comments/1trnvdl/aita_for_cancelling/\",\n+        )\n+        .unwrap();\n+        assert_eq!(\n+            id.as_str(),\n+            \"reddit.com/r/amitheasshole/comments/1trnvdl\"\n+        );\n+    }\n+\n+    #[test]\n+    fn from_url_strips_query() {\n+        let id = ItemId::from_url(\"https://www.reddit.com/r/rust/?sort=top\").unwrap();\n+        assert_eq!(id.as_str(), \"reddit.com/r/rust\");\n+    }\n+\n+    #[test]\n+    fn from_url_short_path() {\n+        assert_eq!(\n+            ItemId::from_url(\"r/rust\").unwrap().as_str(),\n+            \"reddit.com/r/rust\"\n+        );\n+    }\n+\n+    #[test]\n+    fn parent_of_post_is_subreddit() {\n+        let id = ItemId::parse(\"reddit.com/r/aww/comments/1trnvdl\").unwrap();\n+        assert_eq!(\n+            id.parent().unwrap().as_str(),\n+            \"reddit.com/r/aww\"\n+        );\n+    }\n+\n+    #[test]\n+    fn parent_of_subreddit_is_r_segment() {\n+        let id = ItemId::parse(\"reddit.com/r/movies\").unwrap();\n+        assert_eq!(id.parent().unwrap().as_str(), \"reddit.com/r\");\n+    }\n+\n+    #[test]\n+    fn breadcrumb_paths() {\n+        let id = ItemId::parse(\"reddit.com/r/movies\").unwrap();\n+        let crumbs = id.breadcrumb_paths();\n+        let paths: Vec<_> = crumbs.iter().map(|p| p.as_str()).collect();\n+        assert_eq!(\n+            paths,\n+            vec![\"reddit.com\", \"reddit.com/r\", \"reddit.com/r/movies\"]\n+        );\n+    }\n+\n+    #[test]\n+    fn legacy_scope_maps_to_reddit_sub() {\n+        assert_eq!(\n+            ItemId::from_legacy_scope(\"rust\").as_str(),\n+            \"reddit.com/r/rust\"\n+        );\n+        assert!(ItemId::from_legacy_scope(\"\").is_root());\n+    }\n+}\ndiff --git a/server/src/reddit.rs b/server/src/reddit.rs\nnew file mode 100644\nindex 0000000000000000000000000000000000000000..d203dca09245daf869b3aa942898447700ae69fb\n--- /dev/null\n+++ b/server/src/reddit.rs\n@@ -0,0 +1,21 @@\n+//! Reddit API import (async, decoupled from UI request path).\n+\n+use crate::{\n+    path_types::ItemId,\n+    reducer::{EntityData, GlobalTree},\n+};\n+\n+/// Bootstrap blank nodes along a URL path so breadcrumbs and voting work before fetch.\n+pub fn ensure_partial_tree(tree: &mut GlobalTree, id: &ItemId) {\n+    tree.ensure_path(id);\n+}\n+\n+/// Placeholder for Reddit JSON import. Returns entity data when implemented.\n+pub async fn fetch_reddit_entity(_id: &ItemId) -> Option<EntityData> {\n+    None\n+}\n+\n+/// Apply fetched entity data to a node (called from async worker).\n+pub fn apply_entity(tree: &mut GlobalTree, id: &ItemId, data: EntityData) {\n+    tree.set_entity_data(id, data);\n+}\ndiff --git a/server/src/reducer.rs b/server/src/reducer.rs\nindex 8d28353e1f2a67e71b7d17a2041a0988150f3245..077f700bf00ddefe18ffd004bb5288bdc7c4adaf 100644\n--- a/server/src/reducer.rs\n+++ b/server/src/reducer.rs\n@@ -115,6 +115,96 @@ impl GroupState {\n     }\n }\n \n+/// Structured data imported from Reddit or elsewhere.\n+#[derive(Debug, Clone, Serialize, Deserialize)]\n+pub struct EntityData {\n+    pub title: String,\n+    pub author: Option<String>,\n+    pub body_html: Option<String>,\n+    pub thumb_url: Option<String>,\n+}\n+\n+/// One node in the fractal tree: entity + ranked children.\n+#[derive(Debug, Clone, Default)]\n+pub struct NodeState {\n+    pub id: ItemId,\n+    pub data: Option<EntityData>,\n+    pub children: HashSet<ItemId>,\n+    pub local_ranking: GroupState,\n+}\n+\n+impl NodeState {\n+    fn new(id: ItemId) -> Self {\n+        Self {\n+            id,\n+            ..Default::default()\n+        }\n+    }\n+}\n+\n+/// Global fractal graph: every URL is both an item and a ranking scope for its children.\n+#[derive(Default)]\n+pub struct GlobalTree {\n+    pub nodes: HashMap<ItemId, NodeState>,\n+}\n+\n+impl GlobalTree {\n+    pub fn new() -> Self {\n+        let mut tree = Self::default();\n+        tree.ensure_node(&ItemId::root());\n+        tree\n+    }\n+\n+    pub fn ensure_node(&mut self, id: &ItemId) -> &mut NodeState {\n+        if !self.nodes.contains_key(id) {\n+            self.nodes.insert(id.clone(), NodeState::new(id.clone()));\n+        }\n+        self.nodes.get_mut(id).expect(\"node just inserted\")\n+    }\n+\n+    /// Register a node and wire parent→child links along the canonical path.\n+    pub fn ensure_path(&mut self, id: &ItemId) {\n+        if id.is_root() {\n+            self.ensure_node(id);\n+            return;\n+        }\n+        self.ensure_node(&ItemId::root());\n+        for path in id.breadcrumb_paths() {\n+            self.ensure_node(&path);\n+            if let Some(parent) = path.parent() {\n+                self.ensure_node(&parent);\n+                if let Some(p) = self.nodes.get_mut(&parent) {\n+                    p.children.insert(path.clone());\n+                }\n+            } else if let Some(r) = self.nodes.get_mut(&ItemId::root()) {\n+                r.children.insert(path.clone());\n+            }\n+        }\n+    }\n+\n+    pub fn get(&self, id: &ItemId) -> Option<&NodeState> {\n+        self.nodes.get(id)\n+    }\n+\n+    pub fn apply_vote(&mut self, parent: &ItemId, vote: VoteData) {\n+        self.ensure_path(parent);\n+        self.ensure_path(&vote.a);\n+        self.ensure_path(&vote.b);\n+        if let Some(node) = self.nodes.get_mut(parent) {\n+            node.children.insert(vote.a.clone());\n+            node.children.insert(vote.b.clone());\n+            node.local_ranking.apply_vote(vote);\n+        }\n+    }\n+\n+    pub fn set_entity_data(&mut self, id: &ItemId, data: EntityData) {\n+        self.ensure_path(id);\n+        if let Some(node) = self.nodes.get_mut(id) {\n+            node.data = Some(data);\n+        }\n+    }\n+}\n+\n #[cfg(test)]\n mod from_recorded_tests {\n     use super::*;\n@@ -125,7 +215,20 @@ mod from_recorded_tests {\n     }\n \n     #[test]\n-    fn rejects_empty() {\n+    fn rejects_empty_pair() {\n         assert!(VoteData::from_recorded(1, \"\", \"b\", 2, 1).is_none());\n     }\n+\n+    #[test]\n+    fn ensure_path_wires_children() {\n+        let mut tree = GlobalTree::new();\n+        let id = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+        tree.ensure_path(&id);\n+        let root = tree.get(&ItemId::root()).unwrap();\n+        assert!(root.children.contains(&ItemId::parse(\"reddit.com\").unwrap()));\n+        let reddit = tree.get(&ItemId::parse(\"reddit.com\").unwrap()).unwrap();\n+        assert!(reddit.children.contains(&ItemId::parse(\"reddit.com/r\").unwrap()));\n+        let sub = tree.get(&id).unwrap();\n+        assert_eq!(sub.id, id);\n+    }\n }\ndiff --git a/server/src/settlement.rs b/server/src/settlement.rs\ndeleted file mode 100644\nindex 7a44495512b7f788239b8aeefbbd0a83656eeac6..0000000000000000000000000000000000000000\n--- a/server/src/settlement.rs\n+++ /dev/null\n@@ -1,94 +0,0 @@\n-use std::collections::HashMap;\n-use std::sync::Arc;\n-\n-use tokio::sync::{mpsc, oneshot, RwLock};\n-\n-use crate::{\n-    event_log::EventLog,\n-    events::Event,\n-    reducer::{GroupState, VoteData},\n-};\n-\n-/// Per-scope ranking state, keyed by scope (e.g. subreddit; \"\" is the default scope).\n-pub type GroupMap = HashMap<String, GroupState>;\n-\n-pub struct SettlementCommand {\n-    pub scope: String,\n-    pub vote: VoteData,\n-    pub event: Event,\n-    pub reply: oneshot::Sender<Result<(), String>>,\n-}\n-\n-#[derive(Clone)]\n-pub struct SettlementClient {\n-    tx: mpsc::Sender<SettlementCommand>,\n-}\n-\n-impl SettlementClient {\n-    pub fn spawn(groups: Arc<RwLock<GroupMap>>, event_log: Arc<EventLog>) -> Self {\n-        let (tx, rx) = mpsc::channel(64);\n-        tokio::spawn(settlement_worker(rx, groups, event_log));\n-        Self { tx }\n-    }\n-\n-    pub async fn record_vote(\n-        &self,\n-        scope: String,\n-        vote: VoteData,\n-        event: Event,\n-    ) -> Result<(), String> {\n-        let (reply, rx) = oneshot::channel();\n-        self.tx\n-            .send(SettlementCommand {\n-                scope,\n-                vote,\n-                event,\n-                reply,\n-            })\n-            .await\n-            .map_err(|_| \"settlement worker stopped\".to_string())?;\n-        rx.await\n-            .map_err(|_| \"settlement worker stopped\".to_string())?\n-    }\n-}\n-\n-async fn settlement_worker(\n-    mut rx: mpsc::Receiver<SettlementCommand>,\n-    groups: Arc<RwLock<GroupMap>>,\n-    event_log: Arc<EventLog>,\n-) {\n-    while let Some(first) = rx.recv().await {\n-        let mut batch = vec![first];\n-        while let Ok(more) = rx.try_recv() {\n-            batch.push(more);\n-        }\n-\n-        let mut disk_err: Option<String> = None;\n-        for cmd in &batch {\n-            if let Err(e) = event_log.append(&cmd.event).await {\n-                disk_err = Some(e.to_string());\n-                break;\n-            }\n-        }\n-\n-        if let Some(err) = disk_err {\n-            for cmd in batch {\n-                let _ = cmd.reply.send(Err(err.clone()));\n-            }\n-            continue;\n-        }\n-\n-        {\n-            let mut w = groups.write().await;\n-            for cmd in &batch {\n-                w.entry(cmd.scope.clone())\n-                    .or_default()\n-                    .apply_vote(cmd.vote.clone());\n-            }\n-        }\n-\n-        for cmd in batch {\n-            let _ = cmd.reply.send(Ok(()));\n-        }\n-    }\n-}\ndiff --git a/server/src/state.rs b/server/src/state.rs\nindex 2d9e5226057f8615897aac48bce947643a230fb4..cc1722f5a5bf4d415f2327ea585c488a15a75592 100644\n--- a/server/src/state.rs\n+++ b/server/src/state.rs\n@@ -1,4 +1,3 @@\n-use std::collections::HashMap;\n use std::sync::Arc;\n \n use tokio::sync::RwLock;\n@@ -6,14 +5,22 @@ use tokio::sync::RwLock;\n use crate::{\n     event_log::EventLog,\n     events::Event,\n-    reducer::VoteData,\n-    settlement::{GroupMap, SettlementClient},\n+    path_types::ItemId,\n+    reducer::{GlobalTree, VoteData},\n+    journal::JournalClient,\n     views::ViewStore,\n };\n \n-/// Normalize a raw ranking subject into a scope key: strip an optional `r/`\n-/// prefix, keep only `[a-z0-9_]`, lowercase, and cap the length. Empty string\n-/// is the default/global scope.\n+/// Parse `?item=` query value into a canonical node id.\n+pub fn parse_item_param(raw: &str) -> ItemId {\n+    let s = raw.trim();\n+    if s.is_empty() {\n+        return ItemId::root();\n+    }\n+    ItemId::from_url(s).or_else(|| ItemId::parse(s)).unwrap_or_else(|| ItemId::opaque(s))\n+}\n+\n+/// Legacy: normalize raw ranking subject into a scope key for old event replay.\n pub fn normalize_scope(raw: &str) -> String {\n     let s = raw.trim();\n     let s = s\n@@ -27,6 +34,14 @@ pub fn normalize_scope(raw: &str) -> String {\n         .collect()\n }\n \n+fn parent_from_event_scope(scope: &str) -> ItemId {\n+    if scope.contains('/') {\n+        ItemId::parse(scope).unwrap_or_else(|| ItemId::from_legacy_scope(scope))\n+    } else {\n+        ItemId::from_legacy_scope(scope)\n+    }\n+}\n+\n #[derive(Clone)]\n pub struct AppConfig {\n     pub data_dir: String,\n@@ -56,8 +71,8 @@ pub struct AppState {\n     pub cfg: Arc<AppConfig>,\n     pub event_log: Arc<EventLog>,\n     pub views: ViewStore,\n-    pub groups: Arc<RwLock<GroupMap>>,\n-    settlement: SettlementClient,\n+    pub tree: Arc<RwLock<GlobalTree>>,\n+    journal: JournalClient,\n }\n \n impl AppState {\n@@ -66,7 +81,7 @@ impl AppState {\n         let views_path = format!(\"{}/views.json\", cfg.data_dir);\n         let views = ViewStore::new(&views_path);\n \n-        let mut groups: GroupMap = HashMap::new();\n+        let mut tree = GlobalTree::new();\n         if let Ok((events, _)) = event_log.load_all().await {\n             for ev in events {\n                 match ev {\n@@ -81,29 +96,45 @@ impl AppState {\n                         if let Some(vote) =\n                             VoteData::from_recorded(ts, &a, &b, ratio_left, ratio_right)\n                         {\n-                            groups.entry(scope).or_default().apply_vote(vote);\n+                            let parent = parent_from_event_scope(&scope);\n+                            tree.apply_vote(&parent, vote);\n                         }\n                     }\n                     Event::ViewRecorded { .. } => {}\n+                    Event::NodeEnsured { id } => {\n+                        if let Some(parsed) = ItemId::parse(&id).or_else(|| ItemId::from_url(&id)) {\n+                            tree.ensure_path(&parsed);\n+                        }\n+                    }\n                 }\n             }\n         }\n \n-        let groups = Arc::new(RwLock::new(groups));\n-        let settlement = SettlementClient::spawn(groups.clone(), event_log.clone());\n+        let tree = Arc::new(RwLock::new(tree));\n+        let journal = JournalClient::spawn(tree.clone(), event_log.clone());\n \n         Self {\n             cfg: Arc::new(cfg),\n             event_log,\n             views,\n-            groups,\n-            settlement,\n+            tree,\n+            journal,\n         }\n     }\n \n+    pub async fn ensure_node(&self, id: &ItemId) -> Result<(), String> {\n+        let event = Event::NodeEnsured {\n+            id: id.as_str().to_string(),\n+        };\n+        self.event_log.append(&event).await.map_err(|e| e.to_string())?;\n+        let mut w = self.tree.write().await;\n+        w.ensure_path(id);\n+        Ok(())\n+    }\n+\n     pub async fn record_vote(\n         &self,\n-        scope: &str,\n+        parent: &ItemId,\n         a: &str,\n         b: &str,\n         ratio_left: i32,\n@@ -113,23 +144,24 @@ impl AppState {\n         let vote = VoteData::from_recorded(ts, a, b, ratio_left, ratio_right)\n             .ok_or_else(|| \"invalid vote: need two distinct non-empty items\".to_string())?;\n \n-        let scope = normalize_scope(scope);\n         let event = Event::VoteRecorded {\n             ts,\n             a: vote.a.as_str().to_string(),\n             b: vote.b.as_str().to_string(),\n             ratio_left: vote.ratio_left,\n             ratio_right: vote.ratio_right,\n-            scope: scope.clone(),\n+            scope: parent.as_str().to_string(),\n         };\n \n-        self.settlement.record_vote(scope, vote, event).await\n+        self.journal\n+            .record_vote(parent.clone(), vote, event)\n+            .await\n     }\n }\n \n #[cfg(test)]\n mod tests {\n-    use super::normalize_scope;\n+    use super::{normalize_scope, parse_item_param};\n \n     #[test]\n     fn normalize_scope_strips_prefix_and_lowercases() {\n@@ -138,4 +170,15 @@ mod tests {\n         assert_eq!(normalize_scope(\"r/web_dev!!\"), \"web_dev\");\n         assert_eq!(normalize_scope(\"\"), \"\");\n     }\n+\n+    #[test]\n+    fn parse_item_param_from_url() {\n+        let id = parse_item_param(\"https://reddit.com/r/rust\");\n+        assert_eq!(id.as_str(), \"reddit.com/r/rust\");\n+    }\n+\n+    #[test]\n+    fn parse_item_param_empty_is_root() {\n+        assert!(parse_item_param(\"\").is_root());\n+    }\n }\ndiff --git a/server/src/ui_action.rs b/server/src/ui_action.rs\nindex 0e030b3448b8e45acbe49d2de47ea26372445c54..d798874d1d94c0dfee59ec1ff703f9ee6ef432c0 100644\n--- a/server/src/ui_action.rs\n+++ b/server/src/ui_action.rs\n@@ -18,7 +18,7 @@ pub enum HtmlUiAction {\n         b: String,\n         ratio_left: i32,\n         ratio_right: i32,\n-        /// Ranking subject (e.g. a subreddit). Empty string = default/global scope.\n+        /// Parent node [`ItemId`] string; empty = tree root.\n         #[serde(default)]\n         scope: String,\n     },\ndiff --git a/server/static/theme_default.css b/server/static/theme_default.css\nindex 6ad0ac712bbc840bedee60f613794de9385fbbd1..1bf8ac7a25207336c019f93cd4119bd0e06229f0 100644\n--- a/server/static/theme_default.css\n+++ b/server/static/theme_default.css\n@@ -137,6 +137,38 @@ code {\n   margin-top: 0.5rem;\n }\n \n+.breadcrumbs {\n+  font-size: 0.875rem;\n+  margin-bottom: 1rem;\n+  color: var(--muted);\n+}\n+\n+.breadcrumbs a {\n+  color: var(--accent);\n+  text-decoration: none;\n+}\n+\n+.breadcrumbs a:hover {\n+  text-decoration: underline;\n+}\n+\n+.breadcrumbs .separator {\n+  color: var(--muted);\n+}\n+\n+.rank-list a {\n+  color: var(--accent);\n+  text-decoration: none;\n+}\n+\n+.rank-list a:hover {\n+  text-decoration: underline;\n+}\n+\n+.entity-card h2 {\n+  margin-top: 0;\n+}\n+\n .scope-name {\n   color: var(--accent);\n   font-weight: 600;\ndiff --git a/server/tests/integration_ui.rs b/server/tests/integration_ui.rs\nindex afeeee24e32f2d7f1d852ca96ac799fac8bce665..f7ac9c26bf9f9277ad5f5708603224c095165fb8 100644\n--- a/server/tests/integration_ui.rs\n+++ b/server/tests/integration_ui.rs\n@@ -2,7 +2,7 @@ use std::collections::HashMap;\n use std::net::SocketAddr;\n \n use axum::Router;\n-use sorter2_server::{create_app, create_app_state, state::AppConfig, ui_action::UI_RPC_FIELD};\n+use sorter2_server::{create_app, create_app_state, path_types::ItemId, state::AppConfig, ui_action::UI_RPC_FIELD};\n use tempfile::TempDir;\n use tokio::net::TcpListener;\n \n@@ -63,9 +63,9 @@ async fn post_ui_record_vote_morphs_ranking_and_persists() {\n         port: 0,\n     };\n     let state = create_app_state(cfg).await;\n-    let groups = state.groups.read().await;\n-    let group = groups.get(\"\").expect(\"default scope group after replay\");\n-    let ranked = sorter2_server::ranking::ranked_items(group);\n+    let tree = state.tree.read().await;\n+    let root = tree.get(&ItemId::root()).expect(\"root node after replay\");\n+    let ranked = sorter2_server::ranking::ranked_items(&root.local_ranking);\n     assert_eq!(ranked.len(), 2);\n     assert_eq!(ranked[0].item.as_str(), \"alpha\");\n }\n@@ -93,5 +93,5 @@ async fn post_ui_parse_query_redirects_to_subreddit() {\n         .unwrap();\n \n     assert!(body.contains(\"window.location.href\"));\n-    assert!(body.contains(\"/?sub=rust\"));\n+    assert!(body.contains(\"/?item=reddit.com/r/rust\"));\n }\n","role":"user"}],"model":"openai/gpt-chat-latest"}