{"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[5db58b98] Improve vote pair selection for spanning trees and rank refinement.\n\nPrefer attaching unranked items to established components before comparing\nisolates, then zip down adjacent rank-centrality pairs once the pool is fully\nconnected, skipping pairs that already have votes.\n\nCo-authored-by: Cursor <cursoragent@cursor.com>\n\nSide A — unified diff (full patch):\ndiff --git a/server/src/pair.rs b/server/src/pair.rs\nindex 54b5d2417e9dba04ed8df422156e274c2b2f76b2..c14de4b0502c8b5a17cddf3746077739d56e03e0 100644\n--- a/server/src/pair.rs\n+++ b/server/src/pair.rs\n@@ -3,13 +3,21 @@\n //! Pair selection prefers **bridge** votes — comparisons between items in\n //! different connected components of the voted-pairs graph — so the pool\n //! merges into one ranking group before refining within it.\n+//!\n+//! Among unvoted bridges, prefer merging established voted components, then\n+//! attaching a never-voted child to an established component, and only then\n+//! comparing two never-voted children (so the voted graph grows as one tree).\n+//!\n+//! Once every pool child sits in one voted component, refinement **zips** down\n+//! the rank-centrality order: prefer 1 vs 2, then 2 vs 3, and so on, skipping\n+//! pairs that already have a vote.\n \n use rand::seq::SliceRandom;\n use std::collections::{HashMap, HashSet};\n \n use crate::{\n     path_types::ItemId,\n-    ranking::connected_components_from_voted_pairs,\n+    ranking::{connected_components_from_voted_pairs, ranked_items},\n     reducer::{GlobalTree, GroupState},\n };\n \n@@ -28,36 +36,77 @@ fn pair_is_voted(group: &GroupState, a: &ItemId, b: &ItemId) -> bool {\n     group.voted_pairs.contains(&(i, j))\n }\n \n-/// Component id per pool item: voted-pairs graph components plus one id per\n-/// never-voted child.\n-fn component_ids(group: &GroupState, pool: &[ItemId]) -> HashMap<ItemId, usize> {\n+/// Voted-pairs layout for pool items: component id per item plus which ids are\n+/// multi-node voted components (ranked groups in the UI).\n+struct ComponentLayout {\n+    ids: HashMap<ItemId, usize>,\n+    established: HashSet<usize>,\n+}\n+\n+fn component_layout(group: &GroupState, pool: &[ItemId]) -> ComponentLayout {\n     let n = group.idx_to_item.len();\n     let (comps, isolates) =\n         connected_components_from_voted_pairs(n, group.voted_pairs.iter().copied());\n \n-    let mut out: HashMap<ItemId, usize> = HashMap::new();\n+    let mut established = HashSet::new();\n+    let mut ids: HashMap<ItemId, usize> = HashMap::new();\n     for (comp_idx, comp) in comps.iter().enumerate() {\n+        if comp.len() >= 2 {\n+            established.insert(comp_idx);\n+        }\n         for &idx in comp {\n             if idx < n {\n-                out.insert(group.idx_to_item[idx].clone(), comp_idx);\n+                ids.insert(group.idx_to_item[idx].clone(), comp_idx);\n             }\n         }\n     }\n     let mut next = comps.len();\n     for &idx in &isolates {\n         if idx < n {\n-            out.insert(group.idx_to_item[idx].clone(), next);\n+            ids.insert(group.idx_to_item[idx].clone(), next);\n             next += 1;\n         }\n     }\n     for item in pool {\n-        out.entry(item.clone()).or_insert_with(|| {\n+        ids.entry(item.clone()).or_insert_with(|| {\n             let id = next;\n             next += 1;\n             id\n         });\n     }\n-    out\n+    ComponentLayout { ids, established }\n+}\n+\n+/// Every pool child shares one multi-node voted component (spanning tree phase done).\n+fn pool_fully_connected(layout: &ComponentLayout, pool: &[ItemId]) -> bool {\n+    if pool.len() < 2 {\n+        return false;\n+    }\n+    let mut comp_id = None;\n+    for item in pool {\n+        let Some(id) = layout.ids.get(item) else {\n+            return false;\n+        };\n+        if !layout.established.contains(id) {\n+            return false;\n+        }\n+        match comp_id {\n+            None => comp_id = Some(*id),\n+            Some(expected) if expected == *id => {}\n+            _ => return false,\n+        }\n+    }\n+    comp_id.is_some()\n+}\n+\n+/// Pool children that appear in `group`, sorted best rank first.\n+fn ranked_pool_order(group: &GroupState, pool: &[ItemId]) -> Vec<ItemId> {\n+    let pool_set: HashSet<_> = pool.iter().collect();\n+    ranked_items(group)\n+        .into_iter()\n+        .map(|r| r.item)\n+        .filter(|id| pool_set.contains(id))\n+        .collect()\n }\n \n #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]\n@@ -72,19 +121,108 @@ enum PairPriority {\n     WithinVoted = 3,\n }\n \n-fn pair_priority(\n+/// Tie-break among unvoted bridge pairs.\n+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]\n+enum BridgeSubPriority {\n+    /// Both endpoints lie in established (multi-node) voted components.\n+    MergeEstablished = 0,\n+    /// One established component member and one never-voted child.\n+    AttachIsolate = 1,\n+    /// Two never-voted children (separate singleton components).\n+    IsolatePair = 2,\n+}\n+\n+/// Tie-break among within-component pairs once the pool is one connected group.\n+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]\n+struct WithinSubPriority {\n+    /// 1 = adjacent ranks (i vs i+1); larger = farther apart in the order.\n+    rank_gap: usize,\n+    /// min rank index of the two — zip from the top (1 vs 2 before 2 vs 3).\n+    zip_index: usize,\n+}\n+\n+const WITHIN_SUB_WORST: WithinSubPriority = WithinSubPriority {\n+    rank_gap: usize::MAX,\n+    zip_index: usize::MAX,\n+};\n+\n+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]\n+struct PairSortKey {\n+    priority: PairPriority,\n+    bridge_sub: BridgeSubPriority,\n+    within_sub: WithinSubPriority,\n+}\n+\n+fn item_in_established(layout: &ComponentLayout, item: &ItemId) -> bool {\n+    layout\n+        .ids\n+        .get(item)\n+        .is_some_and(|id| layout.established.contains(id))\n+}\n+\n+fn bridge_sub_priority(layout: &ComponentLayout, a: &ItemId, b: &ItemId) -> BridgeSubPriority {\n+    let a_est = item_in_established(layout, a);\n+    let b_est = item_in_established(layout, b);\n+    match (a_est, b_est) {\n+        (true, true) => BridgeSubPriority::MergeEstablished,\n+        (true, false) | (false, true) => BridgeSubPriority::AttachIsolate,\n+        (false, false) => BridgeSubPriority::IsolatePair,\n+    }\n+}\n+\n+fn within_sub_priority(\n+    group: &GroupState,\n+    pool: &[ItemId],\n+    layout: &ComponentLayout,\n+    a: &ItemId,\n+    b: &ItemId,\n+) -> WithinSubPriority {\n+    if !pool_fully_connected(layout, pool) {\n+        return WITHIN_SUB_WORST;\n+    }\n+    let order = ranked_pool_order(group, pool);\n+    let (Some(i), Some(j)) = (order.iter().position(|x| x == a), order.iter().position(|x| x == b))\n+    else {\n+        return WITHIN_SUB_WORST;\n+    };\n+    WithinSubPriority {\n+        rank_gap: i.abs_diff(j),\n+        zip_index: i.min(j),\n+    }\n+}\n+\n+fn pair_sort_key(\n     group: &GroupState,\n-    components: &HashMap<ItemId, usize>,\n+    pool: &[ItemId],\n+    layout: &ComponentLayout,\n     a: &ItemId,\n     b: &ItemId,\n-) -> PairPriority {\n+) -> PairSortKey {\n     let voted = pair_is_voted(group, a, b);\n-    let bridge = components.get(a) != components.get(b);\n-    match (bridge, voted) {\n+    let bridge = layout.ids.get(a) != layout.ids.get(b);\n+    let priority = match (bridge, voted) {\n         (true, false) => PairPriority::BridgeUnvoted,\n         (false, false) => PairPriority::WithinUnvoted,\n         (true, true) => PairPriority::BridgeVoted,\n         (false, true) => PairPriority::WithinVoted,\n+    };\n+    let bridge_sub = if priority == PairPriority::BridgeUnvoted {\n+        bridge_sub_priority(layout, a, b)\n+    } else {\n+        BridgeSubPriority::MergeEstablished\n+    };\n+    let within_sub = if matches!(\n+        priority,\n+        PairPriority::WithinUnvoted | PairPriority::WithinVoted\n+    ) {\n+        within_sub_priority(group, pool, layout, a, b)\n+    } else {\n+        WITHIN_SUB_WORST\n+    };\n+    PairSortKey {\n+        priority,\n+        bridge_sub,\n+        within_sub,\n     }\n }\n \n@@ -109,9 +247,12 @@ fn candidate_pairs(pool: &[ItemId], exclude: Option<(&ItemId, &ItemId)>) -> Vec<\n \n /// Pick the next pair to vote on within `pool`.\n ///\n-/// 1. Prefer unvoted **bridge** pairs (connect separate ranking components).\n-/// 2. Then unvoted within-component pairs (refinement).\n-/// 3. Then already-voted pairs (re-compare).\n+/// 1. Prefer unvoted **bridge** pairs (connect separate ranking components),\n+///    with sub-priority: merge established components, attach an isolate to\n+///    established, then compare two isolates.\n+/// 2. Then unvoted within-component pairs; when the pool is one connected group,\n+///    prefer adjacent ranks (1 vs 2, 2 vs 3, …) in order, skipping voted pairs.\n+/// 3. Then already-voted pairs (re-compare), with the same zip ordering.\n pub fn suggest_next_pair_in_pool(\n     group: &GroupState,\n     pool: &[ItemId],\n@@ -121,15 +262,15 @@ pub fn suggest_next_pair_in_pool(\n     if candidates.is_empty() {\n         return None;\n     }\n-    let components = component_ids(group, pool);\n+    let layout = component_layout(group, pool);\n     let best = candidates\n         .iter()\n-        .map(|(a, b)| (pair_priority(group, &components, a, b), (a, b)))\n-        .min_by_key(|(p, _)| *p)?\n+        .map(|(a, b)| (pair_sort_key(group, pool, &layout, a, b), (a, b)))\n+        .min_by_key(|(k, _)| *k)?\n         .0;\n     let best_pairs: Vec<(ItemId, ItemId)> = candidates\n         .into_iter()\n-        .filter(|(a, b)| pair_priority(group, &components, a, b) == best)\n+        .filter(|(a, b)| pair_sort_key(group, pool, &layout, a, b) == best)\n         .collect();\n     best_pairs.choose(&mut rand::thread_rng()).cloned()\n }\n@@ -303,6 +444,38 @@ mod tests {\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 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+            ],\n+        );\n+        let ab =\n+            VoteData::from_recorded(1, \"reddit.com/r/rust/a\", \"reddit.com/r/rust/b\", 2, 1).unwrap();\n+        tree.apply_vote(&parent, ab);\n+        let group = tree.get(&parent).unwrap().local_ranking.clone();\n+        let pool = children_of(&tree, &parent);\n+        let pair = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n+        let chosen = pair_set(&pair);\n+        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+        assert!(\n+            from_ab && from_cde,\n+            \"expected ranked+unranked attach, got {:?}\",\n+            chosen\n+        );\n+    }\n+\n     #[test]\n     fn suggest_connects_isolate_to_existing_component() {\n         let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n@@ -325,6 +498,65 @@ mod tests {\n         assert!(chosen.contains(\"reddit.com/r/rust/a\") || chosen.contains(\"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 mut tree = seed_children(\n+            &parent,\n+            &[\n+                \"reddit.com/r/rust/a\",\n+                \"reddit.com/r/rust/b\",\n+                \"reddit.com/r/rust/c\",\n+            ],\n+        );\n+        // Star at a connects all three; b-c is the only unvoted adjacent pair left.\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+        ] {\n+            let v = VoteData::from_recorded(1, a, b, l, r).unwrap();\n+            tree.apply_vote(&parent, v);\n+        }\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+        // a-b and a-c voted; b-c is the only unvoted adjacent pair in rank order.\n+        assert!(chosen.contains(\"reddit.com/r/rust/b\"));\n+        assert!(chosen.contains(\"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 mut tree = seed_children(\n+            &parent,\n+            &[\n+                \"reddit.com/r/rust/a\",\n+                \"reddit.com/r/rust/b\",\n+                \"reddit.com/r/rust/c\",\n+                \"reddit.com/r/rust/d\",\n+            ],\n+        );\n+        // Hub at c connects all four; leave rank-adjacent a-b and b-c unvoted.\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+        ] {\n+            let v = VoteData::from_recorded(1, a, b, l, r).unwrap();\n+            tree.apply_vote(&parent, v);\n+        }\n+        let group = tree.get(&parent).unwrap().local_ranking.clone();\n+        let pool = children_of(&tree, &parent);\n+        assert!(pool_fully_connected(&component_layout(&group, &pool), &pool));\n+        let pair = suggest_next_pair_in_pool(&group, &pool, None).unwrap();\n+        let chosen = pair_set(&pair);\n+        // Top adjacent unvoted edge should be a-b (zip index 0), not b-c (index 1).\n+        assert!(chosen.contains(\"reddit.com/r/rust/a\"));\n+        assert!(chosen.contains(\"reddit.com/r/rust/b\"));\n+    }\n+\n     #[test]\n     fn resolve_pair_picks_from_pool() {\n         let parent = ItemId::parse(\"reddit.com/r/rust\").unwrap();\n\n\nSide B — contributor: tommy-mor\nSide B — commit message:\n[81de487b] Fix zero-ratio guard in reducer to drop before registering items or pair.\n\nPreviously the early-return for zero-weight votes happened after\nensure_item and voted_pairs.insert, leaving ghost items in the index\nand the pair incorrectly marked as voted. Move the check to before\nany side effects.\n\nCo-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>\n\nSide B — unified diff (full patch):\ndiff --git a/server/src/reducer.rs b/server/src/reducer.rs\nindex 6841d35cfc9de2389f340a22b8a45acb335e36c3..0e36979abe0f051493038ff7e652efc7f7a0ac80 100644\n--- a/server/src/reducer.rs\n+++ b/server/src/reducer.rs\n@@ -112,6 +112,10 @@ impl GroupState {\n         if vote.ratio_right < 0 {\n             vote.ratio_right = 0;\n         }\n+        if vote.ratio_left == 0 || vote.ratio_right == 0 {\n+            // Zero on either side produces no valid edge; drop before registering items or pair.\n+            return;\n+        }\n \n         let a_idx = self.ensure_item(&vote.a);\n         let b_idx = self.ensure_item(&vote.b);\n@@ -121,10 +125,6 @@ impl GroupState {\n \n         let w_a = vote.ratio_left as f64;\n         let w_b = vote.ratio_right as f64;\n-        if w_a == 0.0 || w_b == 0.0 {\n-            // Zero on either side produces no valid edge; drop the vote.\n-            return;\n-        }\n \n         self.add_edge_weight(b_idx, a_idx, w_a);\n         self.add_edge_weight(a_idx, b_idx, w_b);\ndiff --git a/server/tests/basic.rs b/server/tests/basic.rs\nindex cc8c1a0d139f3722ba6ecd13dd001c65be835b67..08159f4a7f0850fd165817a4a1af4f31ced2ad76 100644\n--- a/server/tests/basic.rs\n+++ b/server/tests/basic.rs\n@@ -546,12 +546,10 @@ fn reducer_negative_ratio_clamped_to_zero() {\n         delegate: Some(\"00000000-0000-0000-0000-000000000000:test:local/test\".to_string()),\n         thread_tag: \"t\".to_string(),\n     });\n-    // Items are registered, but the zero-clamped vote produces no edges.\n-    assert_eq!(group.idx_to_item.len(), 2);\n-    let a_idx = group.item_to_idx[&item_id(\"https://slug.social/~/t/a\")];\n-    let b_idx = group.item_to_idx[&item_id(\"https://slug.social/~/t/b\")];\n-    assert!(!group.edges.contains_key(&(a_idx, b_idx)));\n-    assert!(!group.edges.contains_key(&(b_idx, a_idx)));\n+    // Nothing registered: zero-clamped vote is dropped before ensure_item.\n+    assert!(group.idx_to_item.is_empty());\n+    assert!(group.edges.is_empty());\n+    assert!(group.voted_pairs.is_empty());\n }\n \n \n","role":"user"}],"model":"~x-ai/grok-latest"}