{"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[075d4d37] Fix OAuth test mocks so Clojure E2E auth flows work again.\n\nHttpServer handlers were crashing on query parsing and token POSTs, which broke Playwright login; also read alias/history via real CSS selectors.\n\nCo-authored-by: Cursor <cursoragent@cursor.com>\n\nSide A — unified diff (full patch):\ndiff --git a/test/auth_login.clj b/test/auth_login.clj\nindex 6f2f00d7aa7340e63d1ac465b0a2234cec7a983f..aa63b66ccb2471b710ba3d168d0461252b39fc10 100644\n--- a/test/auth_login.clj\n+++ b/test/auth_login.clj\n@@ -14,27 +14,27 @@\n (defn- type-alias! [pg text]\n   (page/evaluate pg\n                  (.replace\n-                  \"(() => { const i = document.getElementById('alias-input'); const f = document.getElementById('alias-check-form'); if (!i || !f) return;\n+                  \"(() => { const i = document.getElementById('alias-input'); const f = document.getElementById('alias-check-form'); if (!i || !f) return Promise.resolve('missing-form');\n                     i.value = __TEXT__;\n                     const cf = document.getElementById('alias-claim-field'); if (cf) cf.value = i.value;\n                     return fetch(f.action, { method: 'POST', credentials: 'same-origin',\n                       headers: { 'Content-Type': 'application/x-www-form-urlencoded' },\n                       body: new URLSearchParams(new FormData(f)).toString() })\n                       .then(function (r) { return r.text(); })\n-                      .then(function (t) { eval(t); }); })()\"\n+                      .then(function (t) { eval(t); return document.getElementById('alias-status')?.textContent || ''; }); })()\"\n                   \"__TEXT__\"\n-                  (pr-str text)))\n-  (Thread/sleep 400))\n+                  (pr-str text))))\n \n-(defn- element-text [pg test-id]\n+(defn- element-text [pg selector]\n   (let [raw (page/evaluate pg\n-                           (str \"document.querySelector('[data-testid=\\\"\" test-id \"\\\"]')?.textContent || ''\"))]\n+                           (str \"document.querySelector(\" (pr-str selector) \")?.textContent || ''\"))]\n     (when (string? raw) (str/trim raw))))\n \n (defn- wait-for-text [pg test-id text timeout-ms]\n-  (let [deadline (+ (System/currentTimeMillis) timeout-ms)]\n+  (let [deadline (+ (System/currentTimeMillis) timeout-ms)\n+        selector (str \"[data-testid=\\\"\" test-id \"\\\"]\")]\n     (loop []\n-      (let [got (or (element-text pg test-id) \"\")]\n+      (let [got (or (element-text pg selector) \"\")]\n         (cond\n           (= got text) got\n           (< (System/currentTimeMillis) deadline) (do (Thread/sleep 200) (recur))\ndiff --git a/test/support/mock_oauth.clj b/test/support/mock_oauth.clj\nindex 5ba7e9be3cf6d2226648e9609a09ed45f306930f..333fe08d56cb06bac2a338cad1c73894d54c4495 100644\n--- a/test/support/mock_oauth.clj\n+++ b/test/support/mock_oauth.clj\n@@ -7,7 +7,7 @@\n (defn- query-param [query key]\n   (when query\n     (some (fn [pair]\n-            (let [[k v] (str/split pair \"=\" 2)]\n+            (let [[k v] (str/split pair #\"=\" 2)]\n               (when (= k key)\n                 (URLDecoder/decode (or v \"\") \"UTF-8\"))))\n           (str/split query #\"&\"))))\n@@ -31,11 +31,11 @@\n \n (defn- send-redirect [^HttpExchange ex location]\n   (.set (.getResponseHeaders ex) \"Location\" location)\n-  (.sendResponseHeaders ex 302 -1)\n+  (.sendResponseHeaders ex 302 0)\n   (.close (.getResponseBody ex)))\n \n (defn- read-form [^HttpExchange ex]\n-  (let [body (slurp (.getInputStream ex))]\n+  (let [body (slurp (.getRequestBody ex))]\n     {:code (query-param body \"code\")\n      :grant (query-param body \"grant_type\")}))\n \n@@ -45,7 +45,7 @@\n           (str/replace #\"^[Bb]earer \" \"\")))\n \n (defn- parse-token-user [token]\n-  (when (str/starts-with? token \"mock:\")\n+  (when (and token (str/starts-with? token \"mock:\"))\n     (parse-mock-user (subs token 5))))\n \n (defn- authorize-redirect [exchange query]\n@@ -55,7 +55,7 @@\n         user (parse-mock-user mock-user)\n         code (str \"mock:\" (:id user) \":\" (:login user))\n         loc (str redirect-uri \"?code=\" (java.net.URLEncoder/encode code \"UTF-8\")\n-                 \"&state=\" (java.net.URLEncoder/encode state \"UTF-8\"))]\n+                 \"&state=\" (java.net.URLEncoder/encode (or state \"\") \"UTF-8\"))]\n     (send-redirect exchange loc)))\n \n (defn start-mock-oauth\n@@ -65,49 +65,56 @@\n         handler\n         (proxy [HttpHandler] []\n           (handle [^HttpExchange exchange]\n-            (let [uri (.getRequestURI exchange)\n-                  path (.getPath uri)\n-                  query (.getQuery uri)\n-                  method (.getRequestMethod exchange)]\n-              (cond\n-                ;; GitHub authorize\n-                (str/ends-with? path \"/login/oauth/authorize\")\n-                (authorize-redirect exchange query)\n+            (try\n+              (let [uri (.getRequestURI exchange)\n+                    path (.getPath uri)\n+                    query (.getQuery uri)\n+                    method (.getRequestMethod exchange)]\n+                (cond\n+                  ;; GitHub authorize\n+                  (str/ends-with? path \"/login/oauth/authorize\")\n+                  (authorize-redirect exchange query)\n \n-                ;; Reddit authorize\n-                (str/ends-with? path \"/api/v1/authorize\")\n-                (authorize-redirect exchange query)\n+                  ;; Reddit authorize\n+                  (str/ends-with? path \"/api/v1/authorize\")\n+                  (authorize-redirect exchange query)\n \n-                ;; GitHub token\n-                (and (= method \"POST\") (str/ends-with? path \"/login/oauth/access_token\"))\n-                (let [code (or (:code (read-form exchange)) \"mock:1002:newbie\")]\n-                  (send-json exchange 200 (str \"{\\\"access_token\\\":\\\"\" code \"\\\",\\\"token_type\\\":\\\"bearer\\\"}\")))\n+                  ;; GitHub token\n+                  (and (= method \"POST\") (str/ends-with? path \"/login/oauth/access_token\"))\n+                  (let [code (or (:code (read-form exchange)) \"mock:1002:newbie\")]\n+                    (send-json exchange 200 (str \"{\\\"access_token\\\":\\\"\" code \"\\\",\\\"token_type\\\":\\\"bearer\\\"}\")))\n \n-                ;; Reddit token (client_credentials for import + authorization_code for login)\n-                (and (= method \"POST\") (str/ends-with? path \"/api/v1/access_token\"))\n-                (let [form (read-form exchange)\n-                      grant (or (:grant form) \"\")\n-                      code (or (:code form) \"mock:t2_test:redditor\")]\n-                  (if (= grant \"client_credentials\")\n-                    (send-json exchange 200 \"{\\\"access_token\\\":\\\"app-token\\\",\\\"token_type\\\":\\\"bearer\\\",\\\"expires_in\\\":3600}\")\n-                    (send-json exchange 200 (str \"{\\\"access_token\\\":\\\"\" code \"\\\",\\\"token_type\\\":\\\"bearer\\\",\\\"expires_in\\\":3600}\"))))\n+                  ;; Reddit token (client_credentials for import + authorization_code for login)\n+                  (and (= method \"POST\") (str/ends-with? path \"/api/v1/access_token\"))\n+                  (let [form (read-form exchange)\n+                        grant (or (:grant form) \"\")\n+                        code (or (:code form) \"mock:t2_test:redditor\")]\n+                    (if (= grant \"client_credentials\")\n+                      (send-json exchange 200 \"{\\\"access_token\\\":\\\"app-token\\\",\\\"token_type\\\":\\\"bearer\\\",\\\"expires_in\\\":3600}\")\n+                      (send-json exchange 200 (str \"{\\\"access_token\\\":\\\"\" code \"\\\",\\\"token_type\\\":\\\"bearer\\\",\\\"expires_in\\\":3600}\"))))\n \n-                ;; GitHub user\n-                (= path \"/user\")\n-                (let [token (bearer-token exchange)\n-                      user (or (parse-token-user token) {:id \"1002\" :login \"newbie\" :numeric? true})]\n-                  (send-json exchange 200\n-                             (str \"{\\\"id\\\":\" (:id user) \",\\\"login\\\":\\\"\" (:login user) \"\\\"}\")))\n+                  ;; GitHub user\n+                  (= path \"/user\")\n+                  (let [token (bearer-token exchange)\n+                        user (or (parse-token-user token) {:id \"1002\" :login \"newbie\" :numeric? true})]\n+                    (send-json exchange 200\n+                               (str \"{\\\"id\\\":\" (:id user) \",\\\"login\\\":\\\"\" (:login user) \"\\\"}\")))\n \n-                ;; Reddit /api/v1/me\n-                (str/ends-with? path \"/api/v1/me\")\n-                (let [token (bearer-token exchange)\n-                      user (or (parse-token-user token) {:id \"t2_test\" :login \"redditor\"})]\n-                  (send-json exchange 200\n-                             (str \"{\\\"id\\\":\\\"\" (:id user) \"\\\",\\\"name\\\":\\\"\" (:login user) \"\\\"}\")))\n+                  ;; Reddit /api/v1/me\n+                  (str/ends-with? path \"/api/v1/me\")\n+                  (let [token (bearer-token exchange)\n+                        user (or (parse-token-user token) {:id \"t2_test\" :login \"redditor\"})]\n+                    (send-json exchange 200\n+                               (str \"{\\\"id\\\":\\\"\" (:id user) \"\\\",\\\"name\\\":\\\"\" (:login user) \"\\\"}\")))\n \n-                :else\n-                (send-json exchange 404 \"{\\\"error\\\":\\\"not found\\\"}\")))))]\n+                  :else\n+                  (send-json exchange 404 \"{\\\"error\\\":\\\"not found\\\"}\")))\n+              (catch Throwable t\n+                (binding [*out* *err*]\n+                  (println \"mock-oauth handler error:\" t))\n+                (try\n+                  (send-json exchange 500 \"{\\\"error\\\":\\\"mock-oauth internal\\\"}\")\n+                  (catch Throwable _))))))]\n     (.createContext server \"/\" handler)\n     (.setExecutor server nil)\n     (.start server)\ndiff --git a/test/support/mock_reddit.clj b/test/support/mock_reddit.clj\nindex a630cf0938722193e9af88382d60e777ff371be4..faa27945b6394363914c853627a0bad1e819a5f9 100644\n--- a/test/support/mock_reddit.clj\n+++ b/test/support/mock_reddit.clj\n@@ -12,7 +12,7 @@\n (defn- query-param [query key]\n   (when query\n     (some (fn [pair]\n-            (let [[k v] (str/split pair \"=\" 2)]\n+            (let [[k v] (str/split pair #\"=\" 2)]\n               (when (= k key)\n                 (URLDecoder/decode (or v \"\") \"UTF-8\"))))\n           (str/split query #\"&\"))))\n@@ -34,11 +34,11 @@\n \n (defn- send-redirect [^HttpExchange ex location]\n   (.set (.getResponseHeaders ex) \"Location\" location)\n-  (.sendResponseHeaders ex 302 -1)\n+  (.sendResponseHeaders ex 302 0)\n   (.close (.getResponseBody ex)))\n \n (defn- read-form [^HttpExchange ex]\n-  (let [body (slurp (.getInputStream ex))]\n+  (let [body (slurp (.getRequestBody ex))]\n     {:code (query-param body \"code\")\n      :grant (query-param body \"grant_type\")}))\n \n@@ -48,7 +48,7 @@\n           (str/replace #\"^[Bb]earer \" \"\")))\n \n (defn- parse-token-user [token]\n-  (when (str/starts-with? token \"mock:\")\n+  (when (and token (str/starts-with? token \"mock:\"))\n     (parse-mock-user (subs token 5))))\n \n (defn start-mock-reddit\n@@ -72,7 +72,7 @@\n                        user (parse-mock-user (query-param query \"mock_user\"))\n                        code (str \"mock:\" (:id user) \":\" (:login user))\n                        loc (str redirect-uri \"?code=\" (java.net.URLEncoder/encode code \"UTF-8\")\n-                                \"&state=\" (java.net.URLEncoder/encode state \"UTF-8\"))]\n+                                \"&state=\" (java.net.URLEncoder/encode (or state \"\") \"UTF-8\"))]\n                    (send-redirect exchange loc))\n \n                  (and (= method \"POST\") (str/ends-with? path \"/api/v1/access_token\"))\n\n\nSide B — contributor: tommy-mor\nSide B — commit message:\n[239c074b] url schema stuff\n\nSide B — unified diff (full patch):\ndiff --git a/AGENTS.md b/AGENTS.md\nindex 426a88e7c1da54fe0a28c5c76fa4e1f1bc117fcf..e60b9ba6012593361ef10e8fdd9439cd9932e09b 100644\n--- a/AGENTS.md\n+++ b/AGENTS.md\n@@ -58,3 +58,4 @@ Use **tmux** for `cargo run --package sorter2-server` (dev server). Rebuild afte\n \n - First `cargo test` / `cargo build --release` is slow; Clojure smoke test always does a release build.\n - `legacy/` and `ideas/` are not part of the workspace build.\n+- **ItemId** for web URLs is a canonical full URL (`https://reddit.com/r/rust`). Rules live in [`server/src/url_rules/`](server/src/url_rules/) (composable Rust, not a config DSL). After changing canonicalization rules, rebuild the projection: `cargo run --package sorter2-server -- replay-index`.\ndiff --git a/Cargo.lock b/Cargo.lock\nindex 0dd4fce5fb6400ae153cca4e3dbf5a5158e6d8b4..49a908ef935c430dbe63c6a28d8a24e38b489486 100644\n--- a/Cargo.lock\n+++ b/Cargo.lock\n@@ -1951,6 +1951,7 @@ dependencies = [\n  \"tower-http 0.5.2\",\n  \"tracing\",\n  \"tracing-subscriber\",\n+ \"url\",\n  \"urlencoding\",\n ]\n \ndiff --git a/REPLAY.sh b/REPLAY.sh\nnew file mode 100755\nindex 0000000000000000000000000000000000000000..f2dbd8aea60c02d2feef74805f7ef5c2b7022537\n--- /dev/null\n+++ b/REPLAY.sh\n@@ -0,0 +1,2 @@\n+cargo run --package sorter2-server -- replay-index\n+\ndiff --git a/server/Cargo.toml b/server/Cargo.toml\nindex 27f552c20b97ef28cdde4cb6b1a4980375135111..ad4912791aff59fb1d3293f66ad381ae618cd60b 100644\n--- a/server/Cargo.toml\n+++ b/server/Cargo.toml\n@@ -24,6 +24,7 @@ async-stream = \"0.3\"\n futures-util = { version = \"0.3\", default-features = false, features = [\"std\"] }\n rand = \"0.8\"\n urlencoding = \"2\"\n+url = \"2\"\n durable = { path = \"../durable\" }\n \n [dev-dependencies]\ndiff --git a/server/src/entity_store.rs b/server/src/entity_store.rs\nindex d5d17c3676e4a8ddec998e9f5a9dbafe9c2d9d0e..d29f39aecca6f12cdcf263cf77c3654eb4ee6cfa 100644\n--- a/server/src/entity_store.rs\n+++ b/server/src/entity_store.rs\n@@ -124,7 +124,7 @@ mod tests {\n     fn round_trip_payload() {\n         let tmp = tempfile::tempdir().unwrap();\n         let store = EntityStore::open(tmp.path()).unwrap();\n-        let id = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+        let id = ItemId::from_url(\"https://reddit.com/r/rust\").unwrap();\n         let payload = json!({\"kind\": \"t5\", \"data\": {\"display_name\": \"rust\"}});\n \n         store.put(&id, &payload).unwrap();\ndiff --git a/server/src/event_log.rs b/server/src/event_log.rs\nindex 36f5b406084065b608735987cdb483c236e03081..2c9290b6fdbf2c2ad1c0f1ffd7374b2d9cc97f36 100644\n--- a/server/src/event_log.rs\n+++ b/server/src/event_log.rs\n@@ -199,7 +199,7 @@ mod tests {\n         log.append(&sample_record(\n             1,\n             Event::NodeEnsured {\n-                id: \"reddit.com/r/rust\".into(),\n+                id: \"https://reddit.com/r/rust\".into(),\n             },\n         ))\n         .await\n@@ -237,7 +237,7 @@ mod tests {\n         let path = tmp.path().join(\"events.jsonl\");\n         let log = EventLog::new(&path);\n         let event = Event::NodeEnsured {\n-            id: \"reddit.com/r/rust\".into(),\n+            id: \"https://reddit.com/r/rust\".into(),\n         };\n         log.append(&sample_record(1, event)).await.unwrap();\n \n@@ -255,7 +255,7 @@ mod tests {\n         let path = tmp.path().join(\"events.jsonl\");\n         std::fs::write(\n             &path,\n-            r#\"{\"type\":\"node_ensured\",\"id\":\"reddit.com/r/rust\"}\n+            r#\"{\"type\":\"node_ensured\",\"id\":\"https://reddit.com/r/rust\"}\n {\"schema\":1,\"seq\":1,\"ts\":1,\"event\":{\"type\":\"vote_recorded\",\"ts\":1,\"a\":\"a\",\"b\":\"b\",\"ratio_left\":2,\"ratio_right\":1,\"scope\":\"\"}}\n \"#,\n         )\n@@ -295,7 +295,7 @@ mod tests {\n         log.append(&sample_record(\n             1,\n             Event::NodeEnsured {\n-                id: \"reddit.com/r/rust\".into(),\n+                id: \"https://reddit.com/r/rust\".into(),\n             },\n         ))\n         .await\n@@ -303,7 +303,7 @@ mod tests {\n         log.append(&sample_record(\n             3,\n             Event::NodeEnsured {\n-                id: \"reddit.com/r/python\".into(),\n+                id: \"https://reddit.com/r/python\".into(),\n             },\n         ))\n         .await\ndiff --git a/server/src/journal.rs b/server/src/journal.rs\nindex 521a108019de1ea870d14c4fafbfe572c20ce0de..50bc89f976edb82b7b0e49e954a8eccbbe82bf87 100644\n--- a/server/src/journal.rs\n+++ b/server/src/journal.rs\n@@ -141,10 +141,10 @@ mod tests {\n         let j2 = journal.clone();\n         let (r1, r2) = tokio::join!(\n             j1.append(Event::NodeEnsured {\n-                id: \"reddit.com/r/rust\".into(),\n+                id: \"https://reddit.com/r/rust\".into(),\n             }),\n             j2.append(Event::NodeEnsured {\n-                id: \"reddit.com/r/python\".into(),\n+                id: \"https://reddit.com/r/python\".into(),\n             }),\n         );\n         r1.unwrap();\n@@ -153,10 +153,10 @@ mod tests {\n         assert_eq!(projection_store.last_applied_event_count().unwrap(), 2);\n         let tree = projection_store.load_tree().unwrap();\n         assert!(tree\n-            .get(&ItemId::parse(\"reddit.com/r/rust\").unwrap())\n+            .get(&ItemId::parse(\"https://reddit.com/r/rust\").unwrap())\n             .is_some());\n         assert!(tree\n-            .get(&ItemId::parse(\"reddit.com/r/python\").unwrap())\n+            .get(&ItemId::parse(\"https://reddit.com/r/python\").unwrap())\n             .is_some());\n     }\n \n@@ -170,7 +170,7 @@ mod tests {\n                 1,\n                 1,\n                 Event::NodeEnsured {\n-                    id: \"reddit.com/r/rust\".into(),\n+                    id: \"https://reddit.com/r/rust\".into(),\n                 },\n             ))\n             .await\n@@ -186,7 +186,7 @@ mod tests {\n                 1,\n                 1,\n                 Event::NodeEnsured {\n-                    id: \"reddit.com/r/rust\".into(),\n+                    id: \"https://reddit.com/r/rust\".into(),\n                 },\n             )],\n         )\n@@ -202,7 +202,7 @@ mod tests {\n         );\n         journal\n             .append(Event::NodeEnsured {\n-                id: \"reddit.com/r/python\".into(),\n+                id: \"https://reddit.com/r/python\".into(),\n             })\n             .await\n             .unwrap();\n@@ -227,13 +227,13 @@ mod tests {\n         journal\n             .append_many(vec![\n                 Event::NodeEnsured {\n-                    id: \"reddit.com/r/rust\".into(),\n+                    id: \"https://reddit.com/r/rust\".into(),\n                 },\n                 Event::NodeEnsured {\n-                    id: \"reddit.com/r/python\".into(),\n+                    id: \"https://reddit.com/r/python\".into(),\n                 },\n                 Event::NodeEnsured {\n-                    id: \"reddit.com/r/clojure\".into(),\n+                    id: \"https://reddit.com/r/clojure\".into(),\n                 },\n             ])\n             .await\n@@ -245,7 +245,7 @@ mod tests {\n         assert_eq!(projection_store.last_applied_event_count().unwrap(), 3);\n         let tree = projection_store.load_tree().unwrap();\n         assert!(tree\n-            .get(&ItemId::parse(\"reddit.com/r/clojure\").unwrap())\n+            .get(&ItemId::parse(\"https://reddit.com/r/clojure\").unwrap())\n             .is_some());\n     }\n }\ndiff --git a/server/src/lib.rs b/server/src/lib.rs\nindex 9bd5f76fd1406b9b1be4c272f4ba8647edde2678..5c02c8e704e4664453bad75d819df8a067668176 100644\n--- a/server/src/lib.rs\n+++ b/server/src/lib.rs\n@@ -9,6 +9,7 @@ pub mod journal;\n pub mod pair;\n pub mod parser;\n pub mod path_types;\n+pub mod url_rules;\n pub mod projection_apply;\n pub mod projection_store;\n pub mod ranking;\ndiff --git a/server/src/pair.rs b/server/src/pair.rs\nindex 43f780ba6ea6ce1cdc2e1f4cbb252ba8a10684b9..815a97b80e3e9f348e0937a4f147f2862018edb0 100644\n--- a/server/src/pair.rs\n+++ b/server/src/pair.rs\n@@ -381,42 +381,42 @@ mod tests {\n \n     #[test]\n     fn suggest_prefers_unvoted_pair() {\n-        let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+        let parent = ItemId::parse(\"https://reddit.com/r/rust\").unwrap();\n         let mut tree = seed_children(\n             &parent,\n             &[\n-                \"reddit.com/r/rust/a\",\n-                \"reddit.com/r/rust/b\",\n-                \"reddit.com/r/rust/c\",\n+                \"https://reddit.com/r/rust/a\",\n+                \"https://reddit.com/r/rust/b\",\n+                \"https://reddit.com/r/rust/c\",\n             ],\n         );\n         let vote =\n-            VoteData::from_recorded(1, \"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\", 2, 1).unwrap();\n+            VoteData::from_recorded(1, \"https://reddit.com/r/rust/a\", \"https://reddit.com/r/rust/b\", 2, 1).unwrap();\n         tree.apply_vote(&parent, vote);\n         let group = tree.get(&parent).unwrap().local_ranking.clone();\n         let pool = children_of(&tree, &parent);\n         let (l, r) = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n-        let voted_ab = (l.as_str() == \"reddit.com/r/rust/a\" && r.as_str() == \"reddit.com/r/rust/b\")\n-            || (l.as_str() == \"reddit.com/r/rust/b\" && r.as_str() == \"reddit.com/r/rust/a\");\n+        let voted_ab = (l.as_str() == \"https://reddit.com/r/rust/a\" && r.as_str() == \"https://reddit.com/r/rust/b\")\n+            || (l.as_str() == \"https://reddit.com/r/rust/b\" && r.as_str() == \"https://reddit.com/r/rust/a\");\n         assert!(!voted_ab);\n     }\n \n     #[test]\n     fn suggest_bridges_separate_components() {\n-        let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+        let parent = ItemId::parse(\"https://reddit.com/r/rust\").unwrap();\n         let mut tree = seed_children(\n             &parent,\n             &[\n-                \"reddit.com/r/rust/a\",\n-                \"reddit.com/r/rust/b\",\n-                \"reddit.com/r/rust/c\",\n-                \"reddit.com/r/rust/d\",\n+                \"https://reddit.com/r/rust/a\",\n+                \"https://reddit.com/r/rust/b\",\n+                \"https://reddit.com/r/rust/c\",\n+                \"https://reddit.com/r/rust/d\",\n             ],\n         );\n         let ab =\n-            VoteData::from_recorded(1, \"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\", 2, 1).unwrap();\n+            VoteData::from_recorded(1, \"https://reddit.com/r/rust/a\", \"https://reddit.com/r/rust/b\", 2, 1).unwrap();\n         let cd =\n-            VoteData::from_recorded(2, \"reddit.com/r/rust/c\", \"reddit.com/r/rust/d\", 2, 1).unwrap();\n+            VoteData::from_recorded(2, \"https://reddit.com/r/rust/c\", \"https://reddit.com/r/rust/d\", 2, 1).unwrap();\n         tree.apply_vote(&parent, ab);\n         tree.apply_vote(&parent, cd);\n         let group = tree.get(&parent).unwrap().local_ranking.clone();\n@@ -424,37 +424,37 @@ mod tests {\n         let pair = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n         let chosen = pair_set(&pair);\n         let from_ab =\n-            chosen.contains(\"reddit.com/r/rust/a\") || chosen.contains(\"reddit.com/r/rust/b\");\n+            chosen.contains(\"https://reddit.com/r/rust/a\") || chosen.contains(\"https://reddit.com/r/rust/b\");\n         let from_cd =\n-            chosen.contains(\"reddit.com/r/rust/c\") || chosen.contains(\"reddit.com/r/rust/d\");\n+            chosen.contains(\"https://reddit.com/r/rust/c\") || chosen.contains(\"https://reddit.com/r/rust/d\");\n         assert!(from_ab && from_cd, \"expected bridge pair, got {:?}\", chosen);\n     }\n \n     #[test]\n     fn suggest_prefers_attach_over_isolate_pair_among_many_unranked() {\n-        let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+        let parent = ItemId::parse(\"https://reddit.com/r/rust\").unwrap();\n         let mut tree = seed_children(\n             &parent,\n             &[\n-                \"reddit.com/r/rust/a\",\n-                \"reddit.com/r/rust/b\",\n-                \"reddit.com/r/rust/c\",\n-                \"reddit.com/r/rust/d\",\n-                \"reddit.com/r/rust/e\",\n+                \"https://reddit.com/r/rust/a\",\n+                \"https://reddit.com/r/rust/b\",\n+                \"https://reddit.com/r/rust/c\",\n+                \"https://reddit.com/r/rust/d\",\n+                \"https://reddit.com/r/rust/e\",\n             ],\n         );\n         let ab =\n-            VoteData::from_recorded(1, \"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\", 2, 1).unwrap();\n+            VoteData::from_recorded(1, \"https://reddit.com/r/rust/a\", \"https://reddit.com/r/rust/b\", 2, 1).unwrap();\n         tree.apply_vote(&parent, ab);\n         let group = tree.get(&parent).unwrap().local_ranking.clone();\n         let pool = children_of(&tree, &parent);\n         let pair = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n         let chosen = pair_set(&pair);\n         let from_ab =\n-            chosen.contains(\"reddit.com/r/rust/a\") || chosen.contains(\"reddit.com/r/rust/b\");\n-        let from_cde = chosen.contains(\"reddit.com/r/rust/c\")\n-            || chosen.contains(\"reddit.com/r/rust/d\")\n-            || chosen.contains(\"reddit.com/r/rust/e\");\n+            chosen.contains(\"https://reddit.com/r/rust/a\") || chosen.contains(\"https://reddit.com/r/rust/b\");\n+        let from_cde = chosen.contains(\"https://reddit.com/r/rust/c\")\n+            || chosen.contains(\"https://reddit.com/r/rust/d\")\n+            || chosen.contains(\"https://reddit.com/r/rust/e\");\n         assert!(\n             from_ab && from_cde,\n             \"expected ranked+unranked attach, got {:?}\",\n@@ -464,40 +464,40 @@ mod tests {\n \n     #[test]\n     fn suggest_connects_isolate_to_existing_component() {\n-        let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+        let parent = ItemId::parse(\"https://reddit.com/r/rust\").unwrap();\n         let mut tree = seed_children(\n             &parent,\n             &[\n-                \"reddit.com/r/rust/a\",\n-                \"reddit.com/r/rust/b\",\n-                \"reddit.com/r/rust/c\",\n+                \"https://reddit.com/r/rust/a\",\n+                \"https://reddit.com/r/rust/b\",\n+                \"https://reddit.com/r/rust/c\",\n             ],\n         );\n         let ab =\n-            VoteData::from_recorded(1, \"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\", 2, 1).unwrap();\n+            VoteData::from_recorded(1, \"https://reddit.com/r/rust/a\", \"https://reddit.com/r/rust/b\", 2, 1).unwrap();\n         tree.apply_vote(&parent, ab);\n         let group = tree.get(&parent).unwrap().local_ranking.clone();\n         let pool = children_of(&tree, &parent);\n         let pair = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n         let chosen = pair_set(&pair);\n-        assert!(chosen.contains(\"reddit.com/r/rust/c\"));\n-        assert!(chosen.contains(\"reddit.com/r/rust/a\") || chosen.contains(\"reddit.com/r/rust/b\"));\n+        assert!(chosen.contains(\"https://reddit.com/r/rust/c\"));\n+        assert!(chosen.contains(\"https://reddit.com/r/rust/a\") || chosen.contains(\"https://reddit.com/r/rust/b\"));\n     }\n \n     #[test]\n     fn suggest_zips_adjacent_ranks_when_tree_complete() {\n-        let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+        let parent = ItemId::parse(\"https://reddit.com/r/rust\").unwrap();\n         let mut tree = seed_children(\n             &parent,\n             &[\n-                \"reddit.com/r/rust/a\",\n-                \"reddit.com/r/rust/b\",\n-                \"reddit.com/r/rust/c\",\n+                \"https://reddit.com/r/rust/a\",\n+                \"https://reddit.com/r/rust/b\",\n+                \"https://reddit.com/r/rust/c\",\n             ],\n         );\n         for (a, b, l, r) in [\n-            (\"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\", 3, 1),\n-            (\"reddit.com/r/rust/a\", \"reddit.com/r/rust/c\", 2, 1),\n+            (\"https://reddit.com/r/rust/a\", \"https://reddit.com/r/rust/b\", 3, 1),\n+            (\"https://reddit.com/r/rust/a\", \"https://reddit.com/r/rust/c\", 2, 1),\n         ] {\n             let v = VoteData::from_recorded(1, a, b, l, r).unwrap();\n             tree.apply_vote(&parent, v);\n@@ -506,26 +506,26 @@ mod tests {\n         let pool = children_of(&tree, &parent);\n         let pair = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n         let chosen = pair_set(&pair);\n-        assert!(chosen.contains(\"reddit.com/r/rust/b\"));\n-        assert!(chosen.contains(\"reddit.com/r/rust/c\"));\n+        assert!(chosen.contains(\"https://reddit.com/r/rust/b\"));\n+        assert!(chosen.contains(\"https://reddit.com/r/rust/c\"));\n     }\n \n     #[test]\n     fn suggest_zip_prefers_1v2_before_2v3_when_both_unvoted() {\n-        let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+        let parent = ItemId::parse(\"https://reddit.com/r/rust\").unwrap();\n         let mut tree = seed_children(\n             &parent,\n             &[\n-                \"reddit.com/r/rust/a\",\n-                \"reddit.com/r/rust/b\",\n-                \"reddit.com/r/rust/c\",\n-                \"reddit.com/r/rust/d\",\n+                \"https://reddit.com/r/rust/a\",\n+                \"https://reddit.com/r/rust/b\",\n+                \"https://reddit.com/r/rust/c\",\n+                \"https://reddit.com/r/rust/d\",\n             ],\n         );\n         for (a, b, l, r) in [\n-            (\"reddit.com/r/rust/c\", \"reddit.com/r/rust/d\", 3, 1),\n-            (\"reddit.com/r/rust/b\", \"reddit.com/r/rust/c\", 2, 1),\n-            (\"reddit.com/r/rust/a\", \"reddit.com/r/rust/c\", 2, 1),\n+            (\"https://reddit.com/r/rust/c\", \"https://reddit.com/r/rust/d\", 3, 1),\n+            (\"https://reddit.com/r/rust/b\", \"https://reddit.com/r/rust/c\", 2, 1),\n+            (\"https://reddit.com/r/rust/a\", \"https://reddit.com/r/rust/c\", 2, 1),\n         ] {\n             let v = VoteData::from_recorded(1, a, b, l, r).unwrap();\n             tree.apply_vote(&parent, v);\n@@ -534,16 +534,16 @@ mod tests {\n         let pool = children_of(&tree, &parent);\n         let pair = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n         let chosen = pair_set(&pair);\n-        assert!(chosen.contains(\"reddit.com/r/rust/a\"));\n-        assert!(chosen.contains(\"reddit.com/r/rust/b\"));\n+        assert!(chosen.contains(\"https://reddit.com/r/rust/a\"));\n+        assert!(chosen.contains(\"https://reddit.com/r/rust/b\"));\n     }\n \n     #[test]\n     fn resolve_pair_picks_from_pool() {\n-        let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n-        let tree = seed_children(&parent, &[\"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\"]);\n+        let parent = ItemId::parse(\"https://reddit.com/r/rust\").unwrap();\n+        let tree = seed_children(&parent, &[\"https://reddit.com/r/rust/a\", \"https://reddit.com/r/rust/b\"]);\n         let pair = resolve_pair(&tree, &parent, None, None).unwrap();\n-        let pool: HashSet<_> = [\"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\"]\n+        let pool: HashSet<_> = [\"https://reddit.com/r/rust/a\", \"https://reddit.com/r/rust/b\"]\n             .into_iter()\n             .collect();\n         assert!(pool.contains(pair.0.as_str()));\ndiff --git a/server/src/parser.rs b/server/src/parser.rs\nindex 9df2dcc9313f7fe250ce3b6aa167f6ec5d57951f..b2a963dd6cab415576c8d3a9a241966758565bb8 100644\n--- a/server/src/parser.rs\n+++ b/server/src/parser.rs\n@@ -23,7 +23,7 @@ mod tests {\n     fn parses_short_path() {\n         assert_eq!(\n             parse_reddit_url(\"r/rust\").unwrap().as_str(),\n-            \"reddit.com/r/rust\"\n+            \"https://reddit.com/r/rust\"\n         );\n     }\n \n@@ -33,7 +33,7 @@ mod tests {\n             parse_reddit_url(\"https://www.reddit.com/r/programming/hot\")\n                 .unwrap()\n                 .as_str(),\n-            \"reddit.com/r/programming\"\n+            \"https://reddit.com/r/programming\"\n         );\n     }\n \n@@ -43,7 +43,10 @@ mod tests {\n             \"https://old.reddit.com/r/AmItheAsshole/comments/1trnvdl/aita_for_cancelling/\",\n         )\n         .unwrap();\n-        assert_eq!(id.as_str(), \"reddit.com/r/amitheasshole/comments/1trnvdl\");\n+        assert_eq!(\n+            id.as_str(),\n+            \"https://reddit.com/r/amitheasshole/comments/1trnvdl\"\n+        );\n     }\n \n     #[test]\ndiff --git a/server/src/path_types.rs b/server/src/path_types.rs\nindex fafd924452f6fd85e7a5b27ed2653a19581e6e56..71ffc01f35c5589686ff05dae3b5610fa01f30ce 100644\n--- a/server/src/path_types.rs\n+++ b/server/src/path_types.rs\n@@ -1,13 +1,14 @@\n use serde::{Deserialize, Serialize};\n use std::fmt;\n \n-/// Canonical hierarchical identity for any URL/path in the fractal tree.\n+use crate::url_rules::{looks_like_url, navigable_breadcrumbs, parent_url, resolve_canonical};\n+\n+/// Canonical identity: a real URL (with scheme) or an opaque non-URL key.\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+    /// Parse an already-canonical id (no normalization). Empty string is invalid; use [`Self::root`].\n     pub fn parse(s: &str) -> Option<Self> {\n         let t = s.trim();\n         if t.is_empty() {\n@@ -16,12 +17,12 @@ impl ItemId {\n         Some(Self(t.to_string()))\n     }\n \n-    /// Build an opaque item key (legacy demo votes, non-URL items).\n+    /// Build an opaque item key (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+    /// Root of the internet tree.\n     pub fn root() -> Self {\n         Self(String::new())\n     }\n@@ -34,23 +35,18 @@ impl ItemId {\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+    /// Canonical URL from a raw pasted or fetched URL.\n     pub fn from_url(raw_url: &str) -> Option<Self> {\n-        Self::canonicalize(raw_url).map(Self)\n+        resolve_canonical(raw_url).map(Self)\n     }\n \n-    /// Normalize strings from forms, events, and Reddit imports into the same\n-    /// stored id shape (e.g. drop post title slug after comment id).\n+    /// Normalize strings from forms, events, and imports into canonical identity.\n     pub fn from_storage(s: &str) -> Option<Self> {\n         let t = s.trim();\n         if t.is_empty() {\n             return None;\n         }\n-        if t.contains(\"://\") || t.starts_with(\"r/\") {\n-            return Self::from_url(t).or_else(|| Self::parse(t));\n-        }\n-        if t.starts_with(\"reddit.com/\") && t.contains(\"/comments/\") {\n+        if looks_like_url(t) {\n             return Self::from_url(t).or_else(|| Self::parse(t));\n         }\n         Self::parse(t).or_else(|| Self::from_url(t))\n@@ -62,35 +58,52 @@ impl ItemId {\n         if s.is_empty() {\n             return Self::root();\n         }\n-        Self(format!(\"reddit.com/r/{s}\"))\n+        if looks_like_url(s) || s.contains('/') {\n+            Self::from_storage(s).unwrap_or_else(|| Self::opaque(s))\n+        } else {\n+            Self(format!(\"https://reddit.com/r/{s}\"))\n+        }\n     }\n \n-    /// Extract the parent, e.g. `reddit.com/r/aww/comments/1trnvdl` →\n-    /// `reddit.com/r/aww`.\n+    /// Immediate parent scope in the tree.\n     pub fn parent(&self) -> Option<Self> {\n-        if self.0.is_empty() {\n+        if self.is_root() {\n             return None;\n         }\n-\n+        if looks_like_url(self.0.as_str()) {\n+            return parent_url(self.0.as_str()).map(Self);\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+        if self.is_root() {\n+            return vec![];\n+        }\n+        if let Some(rest) = self.0.strip_prefix(\"https://\") {\n+            return rest.split('/').filter(|s| !s.is_empty()).collect();\n+        }\n+        if let Some(rest) = self.0.strip_prefix(\"http://\") {\n+            return rest.split('/').filter(|s| !s.is_empty()).collect();\n+        }\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+    /// Cumulative navigable paths for breadcrumbs and tree wiring (includes self).\n     pub fn breadcrumb_paths(&self) -> Vec<ItemId> {\n+        if self.is_root() {\n+            return vec![];\n+        }\n+        if looks_like_url(self.0.as_str()) {\n+            return navigable_breadcrumbs(self.0.as_str())\n+                .into_iter()\n+                .map(ItemId)\n+                .collect();\n+        }\n         let segs = self.segments();\n         let mut paths = Vec::with_capacity(segs.len());\n         let mut current = String::new();\n@@ -111,13 +124,13 @@ impl ItemId {\n         if self.is_root() {\n             return String::new();\n         }\n-        if self.as_str().contains(\"://\") {\n-            return self.as_str().to_string();\n+        if self.0.contains(\"://\") {\n+            return self.0.clone();\n         }\n         if self.segments().first().is_some_and(|s| s.contains('.')) {\n-            format!(\"https://{}\", self.as_str())\n+            format!(\"https://{}\", self.0)\n         } else {\n-            self.as_str().to_string()\n+            self.0.clone()\n         }\n     }\n \n@@ -144,70 +157,6 @@ impl ItemId {\n     pub fn from_browse_uri(path: &str) -> Option<ItemId> {\n         path.strip_prefix(\"/~/\").map(ItemId::from_browse_tail)\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_browse_tail(tail: &str) -> String {\n@@ -215,7 +164,6 @@ fn normalize_browse_tail(tail: &str) -> String {\n     if t.is_empty() {\n         return String::new();\n     }\n-    // Some HTTP stacks collapse `https://` → `https:/` inside a path segment.\n     if t.starts_with(\"https:/\") && !t.starts_with(\"https://\") {\n         return format!(\"https://{}\", &t[7..]);\n     }\n@@ -225,33 +173,6 @@ fn normalize_browse_tail(tail: &str) -> String {\n     t.to_string()\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     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {\n         f.write_str(&self.0)\n@@ -268,43 +189,59 @@ mod tests {\n             \"https://old.reddit.com/r/AmItheAsshole/comments/1trnvdl/aita_for_cancelling/\",\n         )\n         .unwrap();\n-        assert_eq!(id.as_str(), \"reddit.com/r/amitheasshole/comments/1trnvdl\");\n+        assert_eq!(\n+            id.as_str(),\n+            \"https://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+        assert_eq!(id.as_str(), \"https://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+            \"https://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!(id.parent().unwrap().as_str(), \"reddit.com/r/aww\");\n+        let id = ItemId::from_url(\"https://reddit.com/r/aww/comments/1trnvdl\").unwrap();\n+        assert_eq!(id.parent().unwrap().as_str(), \"https://reddit.com/r/aww\");\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+        let id = ItemId::from_url(\"https://reddit.com/r/movies\").unwrap();\n+        assert_eq!(id.parent().unwrap().as_str(), \"https://reddit.com/r\");\n+    }\n+\n+    #[test]\n+    fn breadcrumb_paths_skip_phantom_comments() {\n+        let id = ItemId::from_url(\"https://reddit.com/r/aww/comments/1trnvdl\").unwrap();\n+        let crumbs = id.breadcrumb_paths();\n+        let paths: Vec<_> = crumbs.iter().map(|p| p.as_str()).collect();\n+        assert!(!paths.iter().any(|p| p.ends_with(\"/comments\")));\n+        assert!(paths.contains(&\"https://reddit.com/r/aww\"));\n     }\n \n     #[test]\n-    fn breadcrumb_paths() {\n-        let id = ItemId::parse(\"reddit.com/r/movies\").unwrap();\n+    fn breadcrumb_paths_subreddit() {\n+        let id = ItemId::from_url(\"https://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+            vec![\n+                \"https://reddit.com\",\n+                \"https://reddit.com/r\",\n+                \"https://reddit.com/r/movies\"\n+            ]\n         );\n     }\n \n@@ -312,33 +249,33 @@ mod tests {\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+            \"https://reddit.com/r/rust\"\n         );\n         assert!(ItemId::from_legacy_scope(\"\").is_root());\n     }\n \n     #[test]\n-    fn browse_href_wraps_canonical_path() {\n-        let id = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+    fn browse_href_wraps_canonical_url() {\n+        let id = ItemId::from_url(\"https://reddit.com/r/rust\").unwrap();\n         assert_eq!(id.browse_href(), \"/~/https://reddit.com/r/rust\");\n     }\n \n     #[test]\n     fn from_browse_tail_parses_full_url() {\n         let id = ItemId::from_browse_tail(\"https://reddit.com/r/AmITheAsshole\");\n-        assert_eq!(id.as_str(), \"reddit.com/r/amitheasshole\");\n+        assert_eq!(id.as_str(), \"https://reddit.com/r/amitheasshole\");\n     }\n \n     #[test]\n     fn from_storage_strips_post_title_slug() {\n         let id =\n             ItemId::from_storage(\"reddit.com/r/rust/comments/aaa/announcing_rust_199\").unwrap();\n-        assert_eq!(id.as_str(), \"reddit.com/r/rust/comments/aaa\");\n+        assert_eq!(id.as_str(), \"https://reddit.com/r/rust/comments/aaa\");\n     }\n \n     #[test]\n     fn from_browse_uri_strips_prefix() {\n         let id = ItemId::from_browse_uri(\"/~/https://reddit.com/r/rust\").unwrap();\n-        assert_eq!(id.as_str(), \"reddit.com/r/rust\");\n+        assert_eq!(id.as_str(), \"https://reddit.com/r/rust\");\n     }\n }\ndiff --git a/server/src/projection_apply.rs b/server/src/projection_apply.rs\nindex ebe122e417bda1d9369a53443de93d28213c5a0d..5644557a41b3e9497c7421b444155ae629fa79f1 100644\n--- a/server/src/projection_apply.rs\n+++ b/server/src/projection_apply.rs\n@@ -19,13 +19,21 @@ use crate::{\n     storage_schema::{ensure_path_writes, entity_view_writes, vote_writes},\n };\n \n-/// Legacy-compatible scope parsing for persisted vote events.\n+fn parse_event_id(id: &str) -> Result<ItemId, EventLogError> {\n+    ItemId::from_storage(id)\n+        .or_else(|| ItemId::parse(id))\n+        .ok_or_else(|| EventLogError::Apply(format!(\"invalid id: {id}\")))\n+}\n+\n+/// Scope key from a vote event (canonicalized at apply time).\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+    let s = scope.trim();\n+    if s.is_empty() {\n+        return ItemId::root();\n     }\n+    ItemId::from_storage(s)\n+        .or_else(|| ItemId::parse(s))\n+        .unwrap_or_else(|| ItemId::from_legacy_scope(s))\n }\n \n pub fn apply_records(\n@@ -68,15 +76,11 @@ pub fn apply_records(\n                 vote_parents.insert(parent);\n             }\n             Event::NodeEnsured { id } => {\n-                let parsed = ItemId::parse(id)\n-                    .or_else(|| ItemId::from_url(id))\n-                    .ok_or_else(|| EventLogError::Apply(format!(\"invalid node id: {id}\")))?;\n+                let parsed = parse_event_id(id)?;\n                 ensure_path_writes(&mut batch, &parsed);\n             }\n             Event::EntityImported { id, payload, .. } => {\n-                let parsed = ItemId::parse(id)\n-                    .or_else(|| ItemId::from_url(id))\n-                    .ok_or_else(|| EventLogError::Apply(format!(\"invalid entity id: {id}\")))?;\n+                let parsed = parse_event_id(id)?;\n                 let view = entity_view_from_payload(&parsed, payload);\n                 entity_view_writes(&mut batch, &parsed, view.as_ref());\n                 entity_store\n@@ -92,7 +96,6 @@ pub fn apply_records(\n         .commit_with(durable::Durability::DisableWal)\n         .map_err(|e| EventLogError::Apply(e.to_string()))?;\n \n-    // Cap recent-vote windows (idempotent, blind; not part of the cursor batch).\n     for parent in vote_parents {\n         projection_store\n             .trim_recent_votes(&parent)\ndiff --git a/server/src/reddit.rs b/server/src/reddit.rs\nindex 72caf7c33b9dd44ea15b62b59e91227cf96a3431..20b7f9e3f8be39268a1767d09f5cf81eaa6ae0df 100644\n--- a/server/src/reddit.rs\n+++ b/server/src/reddit.rs\n@@ -183,7 +183,7 @@ pub fn entity_view_from_payload(\n     id: &ItemId,\n     payload: &Value,\n ) -> Option<crate::reducer::EntityData> {\n-    if id.as_str().starts_with(\"reddit.com\") {\n+    if id.as_str().contains(\"reddit.com\") {\n         return parse_reddit_view(id, payload);\n     }\n     None\n@@ -495,41 +495,59 @@ fn rate_limit_reset_secs(resp: &reqwest::Response) -> u64 {\n         .unwrap_or(5)\n }\n \n+fn reddit_path_segments(id: &ItemId) -> Option<Vec<String>> {\n+    let s = id.as_str();\n+    let rest = s\n+        .strip_prefix(\"https://reddit.com/\")\n+        .or_else(|| s.strip_prefix(\"http://reddit.com/\"))\n+        .or_else(|| s.strip_prefix(\"reddit.com/\"))?;\n+    let segments: Vec<String> = rest\n+        .split('/')\n+        .filter(|p| !p.is_empty())\n+        .map(str::to_string)\n+        .collect();\n+    Some(segments)\n+}\n+\n pub fn map_item_to_reddit_api(id: &ItemId, api_base: &str) -> String {\n-    let path = id.as_str();\n-    if !path.starts_with(\"reddit.com/\") && path != \"reddit.com\" {\n-        return String::new();\n-    }\n+    let segments = match reddit_path_segments(id) {\n+        Some(s) => s,\n+        None if matches!(\n+            id.as_str(),\n+            \"https://reddit.com\" | \"http://reddit.com\" | \"reddit.com\"\n+        ) =>\n+        {\n+            return String::new();\n+        }\n+        None => return String::new(),\n+    };\n \n     let base = api_base.trim_end_matches('/');\n \n-    let segments: Vec<&str> = path.split('/').collect();\n-\n-    if let Some(i) = segments.iter().position(|&p| p == \"comments\") {\n+    if let Some(i) = segments.iter().position(|p| p == \"comments\") {\n         if segments.len() > i + 1 {\n-            let api_path = segments[1..=i + 1].join(\"/\");\n+            let api_path = segments[..=i + 1].join(\"/\");\n             return format!(\"{base}/{api_path}.json?raw_json=1\");\n         }\n     }\n \n-    if segments.len() == 3 && segments[1] == \"r\" {\n-        return format!(\"{base}/r/{}/about.json?raw_json=1\", segments[2]);\n+    if segments.len() == 2 && segments[0] == \"r\" {\n+        return format!(\"{base}/r/{}/about.json?raw_json=1\", segments[1]);\n     }\n \n     String::new()\n }\n \n /// Listing URL for a node's children. Currently only subreddits\n-/// (`reddit.com/r/<sub>` → `/r/<sub>.json`) expose a child listing.\n+/// (`https://reddit.com/r/<sub>` → `/r/<sub>.json`) expose a child listing.\n pub fn map_children_url(id: &ItemId, api_base: &str) -> String {\n-    let path = id.as_str();\n-    if !path.starts_with(\"reddit.com/\") {\n-        return String::new();\n-    }\n+    let segments = match reddit_path_segments(id) {\n+        Some(s) => s,\n+        None => return String::new(),\n+    };\n     let base = api_base.trim_end_matches('/');\n-    let segments: Vec<&str> = path.split('/').collect();\n-    if segments.len() == 3 && segments[1] == \"r\" {\n-        return format!(\"{base}/r/{}.json?raw_json=1&limit=25\", segments[2]);\n+    if segments.len() == 2 && segments[0] == \"r\" {\n+        return format!(\"{base}/r/{}.json?raw_json=1&limit=25\", segments[1]);\n     }\n     String::new()\n }\n@@ -548,8 +566,8 @@ fn parse_children(_parent: &ItemId, payload: &Value) -> Vec<(ItemId, Value)> {\n             Some(p) if !p.is_empty() => p,\n             _ => continue,\n         };\n-        let path = format!(\"reddit.com{}\", permalink.trim_end_matches('/'));\n-        if let Some(id) = ItemId::from_storage(&path) {\n+        let raw = format!(\"https://reddit.com{}\", permalink.trim_end_matches('/'));\n+        if let Some(id) = ItemId::from_url(&raw) {\n             out.push((id, child.clone()));\n         }\n     }\n@@ -683,7 +701,7 @@ mod tests {\n \n     #[test]\n     fn map_subreddit_about_url() {\n-        let id = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+        let id = ItemId::from_url(\"https://reddit.com/r/rust\").unwrap();\n         assert_eq!(\n             map_item_to_reddit_api(&id, \"https://www.reddit.com\"),\n             \"https://www.reddit.com/r/rust/about.json?raw_json=1\"\n@@ -699,7 +717,8 @@ mod tests {\n         let json = include_str!(\"../../test/fixtures/reddit/r_rust_about.json\");\n         let v: Value = serde_json::from_str(json).unwrap();\n         let entity =\n-            entity_view_from_payload(&ItemId::parse(\"reddit.com/r/rust\").unwrap(), &v).unwrap();\n+            entity_view_from_payload(&ItemId::from_url(\"https://reddit.com/r/rust\").unwrap(), &v)\n+                .unwrap();\n         assert_eq!(entity.title, \"The Rust Programming Language\");\n     }\n \n@@ -707,7 +726,8 @@ mod tests {\n     fn parse_post_listing_extracts_thumb_and_full_preview() {\n         let json = include_str!(\"../../test/fixtures/reddit/post_preview.json\");\n         let v: Value = serde_json::from_str(json).unwrap();\n-        let id = ItemId::parse(\"reddit.com/r/nsfw/comments/1tpy6a1/angel_eyes\").unwrap();\n+        let id =\n+            ItemId::from_url(\"https://reddit.com/r/nsfw/comments/1tpy6a1/angel_eyes\").unwrap();\n         let entity = entity_view_from_payload(&id, &v).unwrap();\n         assert_eq!(entity.title, \"Angel Eyes\");\n         assert!(entity.thumb_url.as_ref().unwrap().contains(\"width=140\"));\ndiff --git a/server/src/reducer.rs b/server/src/reducer.rs\nindex 6578f64a41726845517cdbf59a359c69e0aa56db..5179ddeca7a7cb0fb92dfc4aa9d5a80bd9125611 100644\n--- a/server/src/reducer.rs\n+++ b/server/src/reducer.rs\n@@ -248,16 +248,18 @@ mod from_recorded_tests {\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+        let id = ItemId::from_url(\"https://reddit.com/r/rust\").unwrap();\n         tree.ensure_path(&id);\n         let root = tree.get(&ItemId::root()).unwrap();\n         assert!(root\n             .children\n-            .contains(&ItemId::parse(\"reddit.com\").unwrap()));\n-        let reddit = tree.get(&ItemId::parse(\"reddit.com\").unwrap()).unwrap();\n+            .contains(&ItemId::from_url(\"https://reddit.com\").unwrap()));\n+        let reddit = tree\n+            .get(&ItemId::from_url(\"https://reddit.com\").unwrap())\n+            .unwrap();\n         assert!(reddit\n             .children\n-            .contains(&ItemId::parse(\"reddit.com/r\").unwrap()));\n+            .contains(&ItemId::from_url(\"https://reddit.com/r\").unwrap()));\n         let sub = tree.get(&id).unwrap();\n         assert_eq!(sub.id, id);\n     }\ndiff --git a/server/src/render/reddit.rs b/server/src/render/reddit.rs\nindex 7f840aa33b734a31d8cf3341a0581c8bcb9bbcf3..595e202436040b0bfc419e68f083f94757ba5d0c 100644\n--- a/server/src/render/reddit.rs\n+++ b/server/src/render/reddit.rs\n@@ -9,7 +9,7 @@ use crate::{\n };\n \n pub fn is_reddit_post(id: &ItemId) -> bool {\n-    id.as_str().starts_with(\"reddit.com/\") && id.as_str().contains(\"/comments/\")\n+    id.as_str().contains(\"reddit.com/\") && id.as_str().contains(\"/comments/\")\n }\n \n /// Post detail card (inside [`crate::fetch::html::entity_panel`]).\ndiff --git a/server/src/state.rs b/server/src/state.rs\nindex 78126f08d90f8069a586279d79258c27a9f9f7a4..513b329ef45fc332e63b3f8ed8498a1f59feb07c 100644\n--- a/server/src/state.rs\n+++ b/server/src/state.rs\n@@ -217,15 +217,21 @@ impl AppState {\n         ratio_right: i32,\n     ) -> Result<(), String> {\n         let ts = crate::html::now_ms();\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+        let a_raw = a.trim();\n+        let b_raw = b.trim();\n+        if a_raw.is_empty() || b_raw.is_empty() || a_raw == b_raw {\n+            return Err(\"invalid vote: need two distinct non-empty items\".to_string());\n+        }\n+        // Validate items canonicalize (or are opaque keys) before append.\n+        let _ = VoteData::from_recorded(ts, a_raw, b_raw, ratio_left, ratio_right)\n+            .ok_or_else(|| \"invalid vote: need two distinct parseable items\".to_string())?;\n \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+            a: a_raw.to_string(),\n+            b: b_raw.to_string(),\n+            ratio_left,\n+            ratio_right,\n             scope: parent.as_str().to_string(),\n         };\n \n@@ -253,7 +259,7 @@ mod tests {\n         let log = EventLog::new(log_path.to_string_lossy().into_owned());\n         let payload = json!({\"kind\":\"t5\",\"data\":{\"title\":\"Rust\",\"display_name\":\"rust\"}});\n         let event = Event::EntityImported {\n-            id: \"reddit.com/r/rust\".into(),\n+            id: \"https://reddit.com/r/rust\".into(),\n             ts: 1,\n             payload: payload.clone(),\n         };\n@@ -266,14 +272,14 @@ mod tests {\n             .await\n             .unwrap();\n         let tree = projection_store\n-            .scope_tree(&ItemId::parse(\"reddit.com/r/rust\").unwrap())\n+            .scope_tree(&ItemId::parse(\"https://reddit.com/r/rust\").unwrap())\n             .unwrap();\n         let node = tree\n-            .get(&ItemId::parse(\"reddit.com/r/rust\").unwrap())\n+            .get(&ItemId::parse(\"https://reddit.com/r/rust\").unwrap())\n             .unwrap();\n         assert_eq!(node.data.as_ref().unwrap().title, \"Rust\");\n         let stored = entity_store\n-            .get(&ItemId::parse(\"reddit.com/r/rust\").unwrap())\n+            .get(&ItemId::parse(\"https://reddit.com/r/rust\").unwrap())\n             .unwrap()\n             .unwrap();\n         assert_eq!(stored[\"data\"][\"display_name\"], \"rust\");\n@@ -289,13 +295,13 @@ mod tests {\n             event_record(\n                 1,\n                 Event::NodeEnsured {\n-                    id: \"reddit.com/r/rust\".into(),\n+                    id: \"https://reddit.com/r/rust\".into(),\n                 },\n             ),\n             event_record(\n                 2,\n                 Event::EntityImported {\n-                    id: \"reddit.com/r/rust\".into(),\n+                    id: \"https://reddit.com/r/rust\".into(),\n                     ts: 2,\n                     payload: payload.clone(),\n                 },\n@@ -325,7 +331,7 @@ mod tests {\n                 &[event_record(\n                     1,\n                     Event::NodeEnsured {\n-                        id: \"reddit.com/r/stale\".into(),\n+                        id: \"https://reddit.com/r/stale\".into(),\n                     },\n                 )],\n             )\n@@ -352,11 +358,11 @@ mod tests {\n         let root = tree.get(&ItemId::root()).unwrap();\n         assert!(root.children.contains(&ItemId::parse(\"alpha\").unwrap()));\n         assert!(projection_store\n-            .load_node(&ItemId::parse(\"reddit.com/r/stale\").unwrap())\n+            .load_node(&ItemId::parse(\"https://reddit.com/r/stale\").unwrap())\n             .unwrap()\n             .is_none());\n         let stored = entity_store\n-            .get(&ItemId::parse(\"reddit.com/r/rust\").unwrap())\n+            .get(&ItemId::parse(\"https://reddit.com/r/rust\").unwrap())\n             .unwrap()\n             .unwrap();\n         assert_eq!(stored[\"data\"][\"display_name\"], \"rust\");\n@@ -370,7 +376,7 @@ mod tests {\n         log.append(&event_record(\n             1,\n             Event::NodeEnsured {\n-                id: \"reddit.com/r/rust\".into(),\n+                id: \"https://reddit.com/r/rust\".into(),\n             },\n         ))\n         .await\n@@ -387,7 +393,7 @@ mod tests {\n                 &[event_record(\n                     2,\n                     Event::NodeEnsured {\n-                        id: \"reddit.com/r/rust\".into(),\n+                        id: \"https://reddit.com/r/rust\".into(),\n                     },\n                 )],\n             )\n@@ -454,7 +460,7 @@ mod tests {\n             port: 0,\n         })\n         .await;\n-        let id = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n+        let id = ItemId::parse(\"https://reddit.com/r/rust\").unwrap();\n \n         state.ensure_node(&id).await.unwrap();\n \n@@ -465,11 +471,11 @@ mod tests {\n         let projected = state.projection_store.load_tree().unwrap();\n         assert!(projected.get(&id).is_some());\n         let reddit = projected\n-            .get(&ItemId::parse(\"reddit.com\").unwrap())\n+            .get(&ItemId::from_url(\"https://reddit.com\").unwrap())\n             .unwrap();\n         assert!(reddit\n             .children\n-            .contains(&ItemId::parse(\"reddit.com/r\").unwrap()));\n+            .contains(&ItemId::from_url(\"https://reddit.com/r\").unwrap()));\n     }\n \n     #[tokio::test]\n@@ -510,7 +516,7 @@ mod tests {\n         log.append(&event_record(\n             1,\n             Event::NodeEnsured {\n-                id: \"reddit.com/r/rust\".into(),\n+                id: \"https://reddit.com/r/rust\".into(),\n             },\n         ))\n         .await\n@@ -518,7 +524,7 @@ mod tests {\n         log.append(&event_record(\n             2,\n             Event::NodeEnsured {\n-                id: \"reddit.com/r/python\".into(),\n+                id: \"https://reddit.com/r/python\".into(),\n             },\n         ))\n         .await\n@@ -544,13 +550,13 @@ mod tests {\n             2\n         );\n         let tree = second\n-            .scope_tree(&ItemId::parse(\"reddit.com/r/rust\").unwrap())\n+            .scope_tree(&ItemId::parse(\"https://reddit.com/r/rust\").unwrap())\n             .unwrap();\n         assert!(tree\n-            .get(&ItemId::parse(\"reddit.com/r/rust\").unwrap())\n+            .get(&ItemId::parse(\"https://reddit.com/r/rust\").unwrap())\n             .is_some());\n         assert!(tree\n-            .get(&ItemId::parse(\"reddit.com/r/python\").unwrap())\n+            .get(&ItemId::parse(\"https://reddit.com/r/python\").unwrap())\n             .is_none());\n     }\n \n@@ -611,7 +617,7 @@ mod tests {\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+        assert_eq!(id.as_str(), \"https://reddit.com/r/rust\");\n     }\n \n     #[test]\ndiff --git a/server/src/url_rules/engine.rs b/server/src/url_rules/engine.rs\nnew file mode 100644\nindex 0000000000000000000000000000000000000000..e29b6b48c08deb7bffe031b1e542b1e25a7bef15\n--- /dev/null\n+++ b/server/src/url_rules/engine.rs\n@@ -0,0 +1,187 @@\n+//! Composable URL normalization primitives.\n+\n+use std::collections::HashMap;\n+\n+use url::Url;\n+\n+/// Mutable URL view used by rule combinators before serializing to a canonical string.\n+#[derive(Debug, Clone)]\n+pub struct ParsedUrl {\n+    pub scheme: String,\n+    pub host: String,\n+    pub path_segments: Vec<String>,\n+    pub query: HashMap<String, String>,\n+    pub fragment: Option<String>,\n+}\n+\n+impl ParsedUrl {\n+    pub fn parse(raw: &str) -> Option<Self> {\n+        let trimmed = raw.trim();\n+        if trimmed.is_empty() {\n+            return None;\n+        }\n+\n+        let with_scheme = if trimmed.contains(\"://\") {\n+            trimmed.to_string()\n+        } else if trimmed.starts_with(\"r/\") || trimmed.starts_with(\"/r/\") {\n+            let rest = trimmed.trim_start_matches('/').trim_start_matches(\"r/\");\n+            format!(\"https://reddit.com/r/{rest}\")\n+        } else if trimmed.contains('.') && !trimmed.starts_with('/') {\n+            format!(\"https://{trimmed}\")\n+        } else {\n+            trimmed.to_string()\n+        };\n+\n+        let url = Url::parse(&with_scheme).ok()?;\n+        let host = url.host_str()?.to_string();\n+        let path_segments: Vec<String> = url\n+            .path_segments()\n+            .map(|segs| segs.filter(|s| !s.is_empty()).map(str::to_string).collect())\n+            .unwrap_or_default();\n+\n+        let mut query = HashMap::new();\n+        for (k, v) in url.query_pairs() {\n+            query.insert(k.into_owned(), v.into_owned());\n+        }\n+\n+        Some(Self {\n+            scheme: url.scheme().to_string(),\n+            path_segments,\n+            query,\n+            fragment: url.fragment().map(str::to_string),\n+            host,\n+        })\n+    }\n+\n+    pub fn with_path_segments(&self, segments: &[String]) -> Self {\n+        let mut u = self.clone();\n+        u.path_segments = segments.to_vec();\n+        u\n+    }\n+\n+    pub fn to_url(&self) -> Option<Url> {\n+        let mut url = if self.path_segments.is_empty() {\n+            Url::parse(&format!(\"{}://{}\", self.scheme, self.host)).ok()?\n+        } else {\n+            let path = format!(\"/{}\", self.path_segments.join(\"/\"));\n+            Url::parse(&format!(\"{}://{}{}\", self.scheme, self.host, path)).ok()?\n+        };\n+        if !self.query.is_empty() {\n+            let mut pairs: Vec<_> = self.query.iter().collect();\n+            pairs.sort_by(|a, b| a.0.cmp(b.0));\n+            url.query_pairs_mut().clear();\n+            for (k, v) in pairs {\n+                url.query_pairs_mut().append_pair(k, v);\n+            }\n+        }\n+        if let Some(ref frag) = self.fragment {\n+            url.set_fragment(Some(frag));\n+        }\n+        Some(url)\n+    }\n+\n+    pub fn canonical_string(&self) -> Option<String> {\n+        let url = self.to_url()?;\n+        let mut s = url.to_string();\n+        if self.path_segments.is_empty() {\n+            s = s.trim_end_matches('/').to_string();\n+        }\n+        Some(s)\n+    }\n+}\n+\n+pub fn force_https(u: &mut ParsedUrl) {\n+    if u.scheme == \"http\" {\n+        u.scheme = \"https\".to_string();\n+    }\n+}\n+\n+pub fn drop_fragment(u: &mut ParsedUrl) {\n+    u.fragment = None;\n+}\n+\n+pub fn strip_www(u: &mut ParsedUrl) {\n+    if u.host.starts_with(\"www.\") {\n+        u.host = u.host[4..].to_string();\n+    }\n+}\n+\n+pub fn lowercase_host(u: &mut ParsedUrl) {\n+    u.host = u.host.to_ascii_lowercase();\n+}\n+\n+pub fn lowercase_path(u: &mut ParsedUrl) {\n+    for seg in &mut u.path_segments {\n+        *seg = seg.to_ascii_lowercase();\n+    }\n+}\n+\n+pub fn clear_query(u: &mut ParsedUrl) {\n+    u.query.clear();\n+}\n+\n+pub fn keep_only_query(u: &mut ParsedUrl, keys: &[&str]) {\n+    u.query\n+        .retain(|k, _| keys.iter().any(|want| want == &k.as_str()));\n+}\n+\n+pub fn strip_tracking_params(u: &mut ParsedUrl) {\n+    u.query.retain(|k, _| {\n+        let lower = k.to_ascii_lowercase();\n+        !(lower.starts_with(\"utm_\")\n+            || matches!(\n+                lower.as_str(),\n+                \"fbclid\" | \"gclid\" | \"ref\" | \"ref_src\" | \"ref_source\" | \"mc_cid\" | \"mc_eid\"\n+            ))\n+    });\n+}\n+\n+pub fn truncate_after_segment(u: &mut ParsedUrl, name: &str, keep: usize) {\n+    if let Some(i) = u.path_segments.iter().position(|s| s == name) {\n+        let end = (i + 1 + keep).min(u.path_segments.len());\n+        u.path_segments.truncate(end);\n+    }\n+}\n+\n+pub fn drop_listing_suffix(u: &mut ParsedUrl, suffixes: &[&str]) {\n+    if u.path_segments.len() >= 3 && u.path_segments.first().map(String::as_str) == Some(\"r\") {\n+        if let Some(last) = u.path_segments.last() {\n+            if suffixes.iter().any(|s| *s == last.as_str()) {\n+                u.path_segments.pop();\n+            }\n+        }\n+    }\n+}\n+\n+pub fn normalize_reddit_host(u: &mut ParsedUrl) {\n+    if matches!(\n+        u.host.as_str(),\n+        \"old.reddit.com\" | \"new.reddit.com\" | \"www.reddit.com\"\n+    ) {\n+        u.host = \"reddit.com\".to_string();\n+    }\n+}\n+\n+pub fn rewrite_youtu_be(u: &mut ParsedUrl) {\n+    if u.host == \"youtu.be\" && u.path_segments.len() == 1 {\n+        let id = u.path_segments[0].clone();\n+        u.host = \"youtube.com\".to_string();\n+        u.path_segments = vec![\"watch\".to_string()];\n+        u.query.insert(\"v\".to_string(), id);\n+    }\n+}\n+\n+pub fn rewrite_youtube_shorts(u: &mut ParsedUrl) {\n+    if u.host == \"youtube.com\" && u.path_segments.first().map(String::as_str) == Some(\"shorts\") {\n+        if let Some(id) = u.path_segments.get(1).cloned() {\n+            u.path_segments = vec![\"watch\".to_string()];\n+            u.query.insert(\"v\".to_string(), id);\n+        }\n+    }\n+}\n+\n+pub fn normalize_youtube_host(u: &mut ParsedUrl) {\n+    if matches!(u.host.as_str(), \"m.youtube.com\" | \"www.youtube.com\") {\n+        u.host = \"youtube.com\".to_string();\n+    }\n+}\ndiff --git a/server/src/url_rules/mod.rs b/server/src/url_rules/mod.rs\nnew file mode 100644\nindex 0000000000000000000000000000000000000000..03d53bd3e82d704a01ba3fd8dd02b7d31422c0de\n--- /dev/null\n+++ b/server/src/url_rules/mod.rs\n@@ -0,0 +1,13 @@\n+//! URL canonicalization and hierarchy rules for [`crate::path_types::ItemId`].\n+\n+mod engine;\n+mod registry;\n+\n+pub use registry::{\n+    canonicalize_raw, looks_like_url, navigable_breadcrumbs, parent_url, resolve_id, CanonicalResult,\n+};\n+\n+/// Resolve raw input to canonical URL.\n+pub fn resolve_canonical(raw: &str) -> Option<String> {\n+    canonicalize_raw(raw.trim()).map(|r| r.canonical)\n+}\ndiff --git a/server/src/url_rules/registry.rs b/server/src/url_rules/registry.rs\nnew file mode 100644\nindex 0000000000000000000000000000000000000000..14514e9af8385fb2b9b2f35eb9ee14d453d4b97c\n--- /dev/null\n+++ b/server/src/url_rules/registry.rs\n@@ -0,0 +1,235 @@\n+//! Per-domain canonicalization and hierarchy rules.\n+\n+use std::collections::HashSet;\n+\n+use super::engine::{\n+    clear_query, drop_fragment, drop_listing_suffix, force_https, keep_only_query, lowercase_host,\n+    lowercase_path, normalize_reddit_host, normalize_youtube_host, rewrite_youtu_be,\n+    rewrite_youtube_shorts, strip_tracking_params, strip_www, truncate_after_segment, ParsedUrl,\n+};\n+\n+/// Result of canonicalizing a raw URL string.\n+#[derive(Debug, Clone, PartialEq, Eq)]\n+pub struct CanonicalResult {\n+    pub canonical: String,\n+    /// When the input normalizes to a different string, the original is an alias.\n+    pub alias_of: Option<String>,\n+}\n+\n+fn apply_global(u: &mut ParsedUrl) {\n+    force_https(u);\n+    drop_fragment(u);\n+    strip_www(u);\n+    lowercase_host(u);\n+    strip_tracking_params(u);\n+}\n+\n+fn normalize_reddit(u: &mut ParsedUrl) {\n+    normalize_reddit_host(u);\n+    lowercase_path(u);\n+    truncate_after_segment(u, \"comments\", 1);\n+    drop_listing_suffix(u, &[\"hot\", \"top\", \"new\", \"rising\", \"controversial\"]);\n+    clear_query(u);\n+}\n+\n+fn normalize_youtube(u: &mut ParsedUrl) {\n+    rewrite_youtu_be(u);\n+    normalize_youtube_host(u);\n+    rewrite_youtube_shorts(u);\n+    keep_only_query(u, &[\"v\", \"list\"]);\n+}\n+\n+fn normalize_default(_u: &mut ParsedUrl) {\n+    // Global rules only.\n+}\n+\n+fn domain_key(host: &str) -> &'static str {\n+    if host == \"reddit.com\" || host.ends_with(\".reddit.com\") {\n+        \"reddit.com\"\n+    } else if host == \"youtube.com\" || host == \"youtu.be\" {\n+        \"youtube.com\"\n+    } else {\n+        \"default\"\n+    }\n+}\n+\n+fn normalize_for_host(u: &mut ParsedUrl) {\n+    apply_global(u);\n+    match domain_key(&u.host) {\n+        \"reddit.com\" => normalize_reddit(u),\n+        \"youtube.com\" => normalize_youtube(u),\n+        _ => normalize_default(u),\n+    }\n+}\n+\n+/// Structural path segments that must not become standalone tree nodes when more path follows.\n+fn structural_trailing(host: &str) -> &'static [&'static str] {\n+    match domain_key(host) {\n+        \"reddit.com\" => &[\"comments\"],\n+        _ => &[],\n+    }\n+}\n+\n+/// Canonicalize a raw URL. Returns `None` if the input is not URL-like.\n+pub fn canonicalize_raw(raw: &str) -> Option<CanonicalResult> {\n+    let trimmed = raw.trim();\n+    if trimmed.is_empty() {\n+        return None;\n+    }\n+    let mut u = ParsedUrl::parse(trimmed)?;\n+    let input_snapshot = u.canonical_string()?;\n+    normalize_for_host(&mut u);\n+    let canonical = u.canonical_string()?;\n+    let alias_of = if input_snapshot != canonical {\n+        Some(trimmed.to_string())\n+    } else {\n+        None\n+    };\n+    Some(CanonicalResult {\n+        canonical,\n+        alias_of,\n+    })\n+}\n+\n+/// Resolve a stored or event id string to its canonical URL identity.\n+pub fn resolve_id(raw: &str) -> Option<String> {\n+    canonicalize_raw(raw).map(|r| r.canonical)\n+}\n+\n+/// Navigable ancestor URLs from domain root up to and including `canonical` (full URLs).\n+pub fn navigable_breadcrumbs(canonical: &str) -> Vec<String> {\n+    let Some(u) = ParsedUrl::parse(canonical) else {\n+        return vec![canonical.to_string()];\n+    };\n+    let structural: HashSet<&str> = structural_trailing(&u.host).iter().copied().collect();\n+    let n = u.path_segments.len();\n+    let mut out = Vec::new();\n+\n+    // Domain root (no path segments).\n+    if let Some(base) = u.with_path_segments(&[]).canonical_string() {\n+        out.push(base);\n+    }\n+\n+    for i in 0..n {\n+        let segs: Vec<String> = u.path_segments[..=i].to_vec();\n+        let is_last = i == n - 1;\n+        let seg = u.path_segments[i].as_str();\n+        if structural.contains(seg) && !is_last {\n+            continue;\n+        }\n+        if let Some(url) = u.with_path_segments(&segs).canonical_string() {\n+            if out.last() != Some(&url) {\n+                out.push(url);\n+            }\n+        }\n+    }\n+    out\n+}\n+\n+/// Immediate parent scope URL, or `None` for tree root / opaque single-segment ids.\n+pub fn parent_url(canonical: &str) -> Option<String> {\n+    let crumbs = navigable_breadcrumbs(canonical);\n+    if crumbs.len() <= 1 {\n+        None\n+    } else {\n+        crumbs.get(crumbs.len() - 2).cloned()\n+    }\n+}\n+\n+/// True when `raw` looks like a URL (has scheme or host-like shape).\n+pub fn looks_like_url(raw: &str) -> bool {\n+    let t = raw.trim();\n+    t.contains(\"://\")\n+        || t.starts_with(\"r/\")\n+        || t.starts_with(\"/r/\")\n+        || (t.contains('.') && t.contains('/'))\n+        || t.starts_with(\"reddit.com\")\n+        || t.starts_with(\"www.\")\n+        || t.starts_with(\"youtu.be/\")\n+}\n+\n+#[cfg(test)]\n+mod tests {\n+    use super::*;\n+\n+    #[test]\n+    fn reddit_post_drops_slug_and_normalizes_host() {\n+        let r = canonicalize_raw(\n+            \"https://old.reddit.com/r/AmItheAsshole/comments/1trnvdl/aita_for_cancelling/\",\n+        )\n+        .unwrap();\n+        assert_eq!(\n+            r.canonical,\n+            \"https://reddit.com/r/amitheasshole/comments/1trnvdl\"\n+        );\n+    }\n+\n+    #[test]\n+    fn reddit_strips_query_and_listing() {\n+        assert_eq!(\n+            canonicalize_raw(\"https://www.reddit.com/r/rust/?sort=top\")\n+                .unwrap()\n+                .canonical,\n+            \"https://reddit.com/r/rust\"\n+        );\n+        assert_eq!(\n+            canonicalize_raw(\"https://www.reddit.com/r/programming/hot\")\n+                .unwrap()\n+                .canonical,\n+            \"https://reddit.com/r/programming\"\n+        );\n+    }\n+\n+    #[test]\n+    fn reddit_short_path() {\n+        assert_eq!(\n+            canonicalize_raw(\"r/rust\").unwrap().canonical,\n+            \"https://reddit.com/r/rust\"\n+        );\n+    }\n+\n+    #[test]\n+    fn reddit_breadcrumbs_skip_phantom_comments() {\n+        let post = \"https://reddit.com/r/aww/comments/1trnvdl\";\n+        let crumbs = navigable_breadcrumbs(post);\n+        assert!(!crumbs.iter().any(|c| c.ends_with(\"/comments\")));\n+        assert_eq!(\n+            crumbs.last().map(String::as_str),\n+            Some(post)\n+        );\n+        assert!(crumbs.contains(&\"https://reddit.com/r/aww\".to_string()));\n+    }\n+\n+    #[test]\n+    fn reddit_parent_of_post_is_subreddit() {\n+        assert_eq!(\n+            parent_url(\"https://reddit.com/r/aww/comments/1trnvdl\").as_deref(),\n+            Some(\"https://reddit.com/r/aww\")\n+        );\n+    }\n+\n+    #[test]\n+    fn youtube_youtu_be_and_watch_same_canonical() {\n+        let a = canonicalize_raw(\"https://youtu.be/dQw4w9WgXcQ\").unwrap().canonical;\n+        let b = canonicalize_raw(\"https://www.youtube.com/watch?v=dQw4w9WgXcQ&t=10\").unwrap();\n+        assert_eq!(a, b.canonical);\n+        assert_eq!(a, \"https://youtube.com/watch?v=dQw4w9WgXcQ\");\n+    }\n+\n+    #[test]\n+    fn legacy_schemeless_upgrades() {\n+        assert_eq!(\n+            canonicalize_raw(\"reddit.com/r/rust/comments/aaa/announcing_rust_199\")\n+                .unwrap()\n+                .canonical,\n+            \"https://reddit.com/r/rust/comments/aaa\"\n+        );\n+    }\n+\n+    #[test]\n+    fn alias_recorded_when_input_differs() {\n+        let r = canonicalize_raw(\"https://youtu.be/abc123\").unwrap();\n+        assert_eq!(r.canonical, \"https://youtube.com/watch?v=abc123\");\n+        assert!(r.alias_of.is_some());\n+    }\n+}\n","role":"user"}],"model":"~x-ai/grok-latest"}