v1.3.3: Lex priority comparator + warm-cache cap + score display

The v1.3.1 comparator used a sum-of-weights priorityScore. With weights
15..1 across 15 specs, three lower-priority specs (BNK+BRM+CRF, sum 39)
could outrank a single top-priority spec (HCR alone, sum 15). In
priority-order mode this surfaced lower-priority plans above the user's
top spec — the opposite of intent.

Fix: replace sum-of-weights with a lexicographic rank weight. Each spec
encodes as a bit, top-ranked spec = highest bit. So [HCR] = 16384 beats
[BNK,BRM,CRF,EMT,ENT,FIN,FIM,GLB,LCM,MGT,MKT,MTO,SBI,STR] = 16383. A plan
containing a higher-ranked spec ALWAYS outranks any plan that doesn't,
regardless of how many lower-ranked specs the latter contains. Lower
specs only act as tiebreakers among plans that all contain the same
higher-ranked spec.

Both modes use lex weight as the priority key; modes still differ in
ordering:
  priority-order: (rankWeight desc, count desc, key asc)
  maximize-count: (count desc, rankWeight desc, key asc)

Score display changes from the legacy sum (e.g. "score 29") to the lex
weight in compact form (e.g. "score 24.6k"). Hover for full integer.
The display now actually corresponds to ranking order.

Other:

- Cache cap (500k leaves) now retains existing entries instead of
  clearing on overflow. New entries past the cap are dropped; the
  cached subset stays available as a warm starting point.
- Two new lex-weight tests in searchDecisionTree.test.ts:
  - single top-ranked spec outweighs all 14 others combined
  - tiebreaker is the next-ranked spec
- All 84 tests pass; cached leaves stay valid across the comparator
  change since achievedSpecs (the input to lex compare) is unchanged.

Files: solver/priority.ts (new functions), solver/decisionTree.ts
(comparators take ranking), components/{TopPlans,CourseSelection}.tsx
(score display + Recommended badge), state/appState.ts (cache-cap
behavior), vite.config.ts, CHANGELOG.md.

app/src/App.tsx

@@ -139,6 +139,7 @@ function App() {
             loading={treeLoading}
             progress={searchProgress}
             pinnedCourses={state.pinnedCourses}
+            ranking={state.ranking}
             onAdopt={adoptPlan}
             onPin={pinCourse}
             onUnpin={unpinCourse}

app/src/components/CourseSelection.tsx

@@ -5,7 +5,7 @@ import { coursesBySet } from '../data/lookups';
 import { COURSE_DESCRIPTIONS } from '../data/courseDescriptions';
 import { courseById } from '../data/lookups';
 import { useMediaQuery } from '../hooks/useMediaQuery';
-import { makePriorityScorer } from '../solver/priority';
+import { makePriorityScorer, makePriorityRankWeight } from '../solver/priority';
 import { specColor } from '../data/specColors';
 import type { OptimizationMode, Term } from '../data/types';
 import type { SetAnalysis } from '../solver/decisionTree';
@@ -214,6 +214,7 @@ function ElectiveSet({
   loading,
   disabledCourseIds,
   scorer,
+  rankWeight,
   mode,
   onPin,
   onUnpin,
@@ -230,6 +231,7 @@ function ElectiveSet({
   loading: boolean;
   disabledCourseIds: Set<string>;
   scorer: (specs: string[]) => number;
+  rankWeight: (specs: string[]) => number;
   mode: OptimizationMode;
   onPin: (courseId: string) => void;
   onUnpin: () => void;
@@ -250,23 +252,24 @@ function ElectiveSet({
   const hasHighImpact = analysis && analysis.impact > 0;
 
   // Determine the recommended choice. Mode-dependent comparison matches the
-  // top-K comparator: priority-order ranks by (score, count); max-count by (count, score).
+  // top-K comparator: priority-order ranks by (rankWeight, count); max-count by (count, rankWeight).
+  // Lex rank weight: a single high-priority spec dominates any combination of lower ones.
   let recommendedCourseId: string | null = null;
   if (analysis && analysis.choices.length > 0) {
-    let best: { id: string; count: number; score: number } | null = null;
+    let best: { id: string; count: number; weight: number } | null = null;
     for (const ch of analysis.choices) {
       if (!ch.evaluated) continue;
-      const score = scorer(ch.ceilingSpecs);
+      const weight = rankWeight(ch.ceilingSpecs);
       const isBetter =
         !best ||
         (mode === 'priority-order'
-          ? score > best.score || (score === best.score && ch.ceilingCount > best.count)
-          : ch.ceilingCount > best.count || (ch.ceilingCount === best.count && score > best.score));
+          ? weight > best.weight || (weight === best.weight && ch.ceilingCount > best.count)
+          : ch.ceilingCount > best.count || (ch.ceilingCount === best.count && weight > best.weight));
       if (isBetter) {
-        best = { id: ch.courseId, count: ch.ceilingCount, score };
+        best = { id: ch.courseId, count: ch.ceilingCount, weight };
       }
     }
-    if (best && (best.count > 0 || best.score > 0)) recommendedCourseId = best.id;
+    if (best && (best.count > 0 || best.weight > 0)) recommendedCourseId = best.id;
   }
 
   // Per-set still-searching indicator: search in progress AND at least one cell unevaluated
@@ -500,6 +503,7 @@ const skeletonStyle = `
 
 export function CourseSelection({ pinnedCourses, treeResults, treeLoading, disabledCourseIds, ranking, mode, onPin, onUnpin, onClearAll }: CourseSelectionProps) {
   const scorer = useMemo(() => makePriorityScorer(ranking), [ranking]);
+  const rankWeight = useMemo(() => makePriorityRankWeight(ranking), [ranking]);
   const terms: Term[] = ['Spring', 'Summer', 'Fall'];
   const hasPinned = Object.keys(pinnedCourses).length > 0;
 
@@ -580,6 +584,7 @@ export function CourseSelection({ pinnedCourses, treeResults, treeLoading, disab
               loading={treeLoading}
               disabledCourseIds={disabledCourseIds}
               scorer={scorer}
+              rankWeight={rankWeight}
               mode={mode}
               onPin={(courseId) => onPin(set.id, courseId)}
               onUnpin={() => onUnpin(set.id)}

app/src/components/TopPlans.tsx

@@ -1,7 +1,9 @@
+import { useMemo } from 'react';
 import { ELECTIVE_SETS } from '../data/electiveSets';
 import { SPECIALIZATIONS } from '../data/specializations';
 import { courseById } from '../data/lookups';
 import { specColor } from '../data/specColors';
+import { makePriorityRankWeight } from '../solver/priority';
 import type { PlanOutcome } from '../solver/decisionTree';
 
 const setNameById: Record<string, string> = {};
@@ -16,6 +18,7 @@ interface TopPlansProps {
   loading: boolean;
   progress: { iterations: number; iterationsTotal: number } | null;
   pinnedCourses: Record<string, string | null>;
+  ranking: string[];
   onAdopt: (assignments: Record<string, string>) => void;
   onPin: (setId: string, courseId: string) => void;
   onUnpin: (setId: string) => void;
@@ -25,7 +28,15 @@ function formatNum(n: number): string {
   return n.toLocaleString();
 }
 
-export function TopPlans({ plans, partial, loading, progress, pinnedCourses, onAdopt, onPin, onUnpin }: TopPlansProps) {
+/** Compact form for the lex rank-weight, e.g. 16384 → "16.4k". */
+function formatScore(n: number): string {
+  if (n < 1000) return String(n);
+  const k = n / 1000;
+  return `${k.toFixed(k >= 100 ? 0 : 1)}k`;
+}
+
+export function TopPlans({ plans, partial, loading, progress, pinnedCourses, ranking, onAdopt, onPin, onUnpin }: TopPlansProps) {
+  const rankWeight = useMemo(() => makePriorityRankWeight(ranking), [ranking]);
   const visible = plans.filter((p) => p.achievedSpecs.length > 0);
 
   const pct = progress && progress.iterationsTotal > 0
@@ -97,6 +108,7 @@ export function TopPlans({ plans, partial, loading, progress, pinnedCourses, onA
             plan={plan}
             rank={i + 1}
             pinnedCourses={pinnedCourses}
+            rankWeight={rankWeight}
             onAdopt={onAdopt}
             onPin={onPin}
             onUnpin={onUnpin}
@@ -111,6 +123,7 @@ function PlanRow({
   plan,
   rank,
   pinnedCourses,
+  rankWeight,
   onAdopt,
   onPin,
   onUnpin,
@@ -118,10 +131,12 @@ function PlanRow({
   plan: PlanOutcome;
   rank: number;
   pinnedCourses: Record<string, string | null>;
+  rankWeight: (specs: string[]) => number;
   onAdopt: (assignments: Record<string, string>) => void;
   onPin: (setId: string, courseId: string) => void;
   onUnpin: (setId: string) => void;
 }) {
+  const weight = rankWeight(plan.achievedSpecs);
   // Combine the plan's open-set assignments with the user's currently-pinned
   // courses so the row shows the full sequence across all 12 sets.
   const assignmentEntries: [string, string][] = ELECTIVE_SETS
@@ -169,8 +184,11 @@ function PlanRow({
             </span>
           );
         })}
-        <span style={{ fontSize: '10px', color: '#888', marginLeft: 'auto' }}>
-          score {plan.priorityScore}
+        <span
+          title={`Lexicographic priority weight: ${weight.toLocaleString()}`}
+          style={{ fontSize: '10px', color: '#888', marginLeft: 'auto', fontVariantNumeric: 'tabular-nums' }}
+        >
+          score {formatScore(weight)}
         </span>
         <button
           onClick={() => onAdopt(plan.courseAssignments)}

app/src/solver/__tests__/searchDecisionTree.test.ts

@@ -61,6 +61,24 @@ describe('BoundedRankedList', () => {
   });
 });
 
+describe('priorityRankWeight (lex compare)', () => {
+  it('a single top-ranked spec outweighs any combination of lower-ranked specs', async () => {
+    const { priorityRankWeight } = await import('../priority');
+    const ranking = ['HCR', 'BNK', 'BRM', 'CRF', 'EMT', 'ENT', 'FIN', 'FIM', 'GLB', 'LCM', 'MGT', 'MKT', 'MTO', 'SBI', 'STR'];
+    const justHCR = priorityRankWeight(['HCR'], ranking);
+    const allOthers = priorityRankWeight(['BNK', 'BRM', 'CRF', 'EMT', 'ENT', 'FIN', 'FIM', 'GLB', 'LCM', 'MGT', 'MKT', 'MTO', 'SBI', 'STR'], ranking);
+    expect(justHCR).toBeGreaterThan(allOthers);
+  });
+
+  it('among plans containing the top spec, the next-ranked spec is the tiebreaker', async () => {
+    const { priorityRankWeight } = await import('../priority');
+    const ranking = ['HCR', 'BNK', 'CRF'];
+    const hcrBnk = priorityRankWeight(['HCR', 'BNK'], ranking);
+    const hcrCrf = priorityRankWeight(['HCR', 'CRF'], ranking);
+    expect(hcrBnk).toBeGreaterThan(hcrCrf);
+  });
+});
+
 describe('compareOutcomes', () => {
   const make = (specs: string[], score: number, key: string): PlanOutcome => ({
     courseAssignments: { spr1: key },

app/src/solver/decisionTree.ts

@@ -3,7 +3,7 @@ import { coursesBySet } from '../data/lookups';
 import type { Course, OptimizationMode } from '../data/types';
 import { maximizeCount, priorityOrder } from './optimizer';
 import { computeUpperBounds } from './feasibility';
-import { makePriorityScorer } from './priority';
+import { makePriorityScorer, makePriorityRankWeight } from './priority';
 
 export interface ChoiceOutcome {
   courseId: string;
@@ -137,21 +137,27 @@ export class BoundedRankedList<T> {
 }
 
 /**
- * Comparator for plan outcomes. Mode-dependent ordering:
- *   - priority-order mode: (priorityScore desc, count desc, key asc)
- *   - maximize-count mode: (count desc, priorityScore desc, key asc)
+ * Comparator for plan outcomes. Mode-dependent ordering uses lexicographic
+ * rank-weight (top-ranked spec dominates any combination of lower-ranked
+ * specs):
+ *   - priority-order mode: (rankWeight desc, count desc, key asc)
+ *   - maximize-count mode: (count desc, rankWeight desc, key asc)
  * Returns negative if a is better, positive if b is better.
  */
 export function makeOutcomeComparator(
   mode: OptimizationMode,
+  ranking: string[],
 ): (a: PlanOutcome, b: PlanOutcome) => number {
+  const rankWeight = makePriorityRankWeight(ranking);
   return (a, b) => {
+    const aw = rankWeight(a.achievedSpecs);
+    const bw = rankWeight(b.achievedSpecs);
     if (mode === 'priority-order') {
-      if (a.priorityScore !== b.priorityScore) return b.priorityScore - a.priorityScore;
+      if (aw !== bw) return bw - aw;
       if (a.achievedSpecs.length !== b.achievedSpecs.length) return b.achievedSpecs.length - a.achievedSpecs.length;
     } else {
       if (a.achievedSpecs.length !== b.achievedSpecs.length) return b.achievedSpecs.length - a.achievedSpecs.length;
-      if (a.priorityScore !== b.priorityScore) return b.priorityScore - a.priorityScore;
+      if (aw !== bw) return bw - aw;
     }
     return assignmentKey(a.courseAssignments).localeCompare(
       assignmentKey(b.courseAssignments),
@@ -159,27 +165,33 @@ export function makeOutcomeComparator(
   };
 }
 
-/** Default count-first comparator, retained for backward compatibility with tests. */
+/** Default count-first comparator (uses default ranking), retained for backward compatibility with tests. */
 export function compareOutcomes(a: PlanOutcome, b: PlanOutcome): number {
-  return makeOutcomeComparator('maximize-count')(a, b);
+  // Default to alphabetical ranking; tests using this directly only exercise
+  // simple count/key cases that are insensitive to ranking.
+  return makeOutcomeComparator('maximize-count', [])(a, b);
 }
 
 interface CeilingComparable {
   count: number;
-  score: number;
+  specs: string[];
   key: string;
 }
 
 function makeCeilingComparator(
   mode: OptimizationMode,
+  ranking: string[],
 ): (a: CeilingComparable, b: CeilingComparable) => number {
+  const rankWeight = makePriorityRankWeight(ranking);
   return (a, b) => {
+    const aw = rankWeight(a.specs);
+    const bw = rankWeight(b.specs);
     if (mode === 'priority-order') {
-      if (a.score !== b.score) return b.score - a.score;
+      if (aw !== bw) return bw - aw;
       if (a.count !== b.count) return b.count - a.count;
     } else {
       if (a.count !== b.count) return b.count - a.count;
-      if (a.score !== b.score) return b.score - a.score;
+      if (aw !== bw) return bw - aw;
     }
     return a.key.localeCompare(b.key);
   };
@@ -235,8 +247,8 @@ export function searchDecisionTree(
   }
   const choiceKey: Record<string, string> = {};
 
-  const outcomeComparator = makeOutcomeComparator(mode);
-  const ceilingComparator = makeCeilingComparator(mode);
+  const outcomeComparator = makeOutcomeComparator(mode, ranking);
+  const ceilingComparator = makeCeilingComparator(mode, ranking);
   const topK = new BoundedRankedList<PlanOutcome>(K, outcomeComparator);
   let iterations = 0;
   const partial = false;
@@ -290,12 +302,12 @@ export function searchDecisionTree(
       const currentKey = `${setId}:${courseId}`;
       const existing: CeilingComparable = {
         count: choice.ceilingCount,
-        score: scorer(choice.ceilingSpecs),
+        specs: choice.ceilingSpecs,
         key: choiceKey[currentKey] ?? '',
       };
       const candidate: CeilingComparable = {
         count: result.achieved.length,
-        score,
+        specs: result.achieved,
         key: aKey,
       };
       const ceilingImproved = ceilingComparator(candidate, existing) < 0;
@@ -376,7 +388,6 @@ export function deriveFromLeaves(
   openSetIds: string[],
   excludedCourseIds?: Set<string>,
 ): { topK: PlanOutcome[]; setAnalyses: SetAnalysis[] } {
-  const scorer = makePriorityScorer(ranking);
   const upperBounds = computeUpperBounds([], openSetIds, excludedCourseIds);
   const priorityTarget = selectPriorityTarget(ranking, upperBounds);
 
@@ -401,8 +412,8 @@ export function deriveFromLeaves(
     };
   }
   const choiceKey: Record<string, string> = {};
-  const ceilingComparator = makeCeilingComparator(mode);
-  const outcomeComparator = makeOutcomeComparator(mode);
+  const ceilingComparator = makeCeilingComparator(mode, ranking);
+  const outcomeComparator = makeOutcomeComparator(mode, ranking);
   const topK = new BoundedRankedList<PlanOutcome>(K, outcomeComparator);
 
   for (const leaf of leaves) {
@@ -417,12 +428,12 @@ export function deriveFromLeaves(
       const currentKey = `${setId}:${courseId}`;
       const existing: CeilingComparable = {
         count: choice.ceilingCount,
-        score: scorer(choice.ceilingSpecs),
+        specs: choice.ceilingSpecs,
         key: choiceKey[currentKey] ?? '',
       };
       const candidate: CeilingComparable = {
         count: leaf.achievedSpecs.length,
-        score: leaf.priorityScore,
+        specs: leaf.achievedSpecs,
         key: aKey,
       };
       if (ceilingComparator(candidate, existing) < 0) {

app/src/solver/priority.ts

@@ -19,3 +19,35 @@ export function makePriorityScorer(ranking: string[]): (specs: string[]) => numb
       0,
     );
 }
+
+/**
+ * Lexicographic comparison weight: each spec encoded as a bit, top-ranked
+ * spec = highest bit. Higher rankWeight means a strictly preferred plan
+ * under priority order (a single top-ranked spec outweighs any combination
+ * of lower-ranked specs). Used by comparators; not for display.
+ */
+export function priorityRankWeight(specs: string[], ranking: string[]): number {
+  const rankIndex = new Map(ranking.map((id, i) => [id, i]));
+  const N = ranking.length;
+  let w = 0;
+  for (const id of specs) {
+    const r = rankIndex.get(id);
+    if (r === undefined) continue;
+    w += 1 << (N - 1 - r);
+  }
+  return w;
+}
+
+export function makePriorityRankWeight(ranking: string[]): (specs: string[]) => number {
+  const rankIndex = new Map(ranking.map((id, i) => [id, i]));
+  const N = ranking.length;
+  return (specs) => {
+    let w = 0;
+    for (const id of specs) {
+      const r = rankIndex.get(id);
+      if (r === undefined) continue;
+      w += 1 << (N - 1 - r);
+    }
+    return w;
+  };
+}

app/src/state/appState.ts

@@ -258,10 +258,12 @@ export function useAppState() {
             setSearchProgress({ iterations: e.data.iterations, iterationsTotal: e.data.iterationsTotal });
           } else if (e.data.type === 'leafEvaluated') {
             const cache = leafCacheRef.current;
-            const key = assignmentKey(e.data.leaf.courseAssignments);
-            cache.leaves.set(key, e.data.leaf);
-            if (cache.leaves.size > LEAF_CACHE_CAP) {
-              cache.leaves.clear();
+            // Stop accepting new entries once the cap is reached; retain
+            // existing entries as a warm starting point for subsequent
+            // pin/unpin operations.
+            if (cache.leaves.size < LEAF_CACHE_CAP) {
+              const key = assignmentKey(e.data.leaf.courseAssignments);
+              cache.leaves.set(key, e.data.leaf);
             }
           } else if (e.data.type === 'allComplete') {
             setTreeResults(e.data.setAnalyses);

app/vite.config.ts

@@ -6,7 +6,7 @@ import react from '@vitejs/plugin-react'
 export default defineConfig({
   plugins: [react()],
   define: {
-    __APP_VERSION__: JSON.stringify('1.3.2'),
+    __APP_VERSION__: JSON.stringify('1.3.3'),
     __APP_VERSION_DATE__: JSON.stringify('2026-05-09'),
   },
   server: {