fix: de-duplicate findCallers in contextData, convert bare db.prepare to StmtCache pattern (#558)

- Refactor buildCallers/buildRelatedTests to share pre-fetched caller rows,
  eliminating redundant DB roundtrip in contextData path
- Convert upstreamStmt/nodeByIdStmt in dependencies.ts to StmtCache<T> pattern
- Convert defsStmt in impact.ts to StmtCache<T> pattern
- Replace r.role as string cast with local variable in roles.ts

Author: carlos-alm

src/domain/analysis/context.ts

@@ -127,8 +127,8 @@ function buildCallees(
   return callees;
 }
 
-function buildCallers(db: BetterSqlite3Database, node: NodeRow, noTests: boolean) {
-  let callerRows: Array<RelatedNodeRow & { viaHierarchy?: string }> = findCallers(
+function fetchCallerRows(db: BetterSqlite3Database, node: NodeRow) {
+  const callerRows: Array<RelatedNodeRow & { viaHierarchy?: string }> = findCallers(
     db,
     node.id,
   ) as RelatedNodeRow[];
@@ -142,9 +142,16 @@ function buildCallers(db: BetterSqlite3Database, node: NodeRow, noTests: boolean
       callerRows.push(...extraCallers.map((c) => ({ ...c, viaHierarchy: rm.name })));
     }
   }
-  if (noTests) callerRows = callerRows.filter((c) => !isTestFile(c.file));
+  return callerRows;
+}
+
+function buildCallers(
+  callerRows: Array<RelatedNodeRow & { viaHierarchy?: string }>,
+  noTests: boolean,
+) {
+  const filtered = noTests ? callerRows.filter((c) => !isTestFile(c.file)) : callerRows;
 
-  return callerRows.map((c) => ({
+  return filtered.map((c) => ({
     name: c.name,
     kind: c.kind,
     file: c.file,
@@ -179,13 +186,11 @@ function buildImplementationInfo(db: BetterSqlite3Database, node: NodeRow, noTes
 }
 
 function buildRelatedTests(
-  db: BetterSqlite3Database,
-  node: NodeRow,
+  callerRows: RelatedNodeRow[],
   getFileLines: (file: string) => string[] | null,
   includeTests: boolean,
 ) {
-  const testCallerRows = findCallers(db, node.id) as RelatedNodeRow[];
-  const testCallers = testCallerRows.filter((c) => isTestFile(c.file));
+  const testCallers = callerRows.filter((c) => isTestFile(c.file));
 
   const testsByFile = new Map<string, RelatedNodeRow[]>();
   for (const tc of testCallers) {
@@ -464,8 +469,9 @@ export function contextData(
         depth,
         displayOpts,
       });
-      const callers = buildCallers(db, node, noTests);
-      const relatedTests = buildRelatedTests(db, node, getFileLines, includeTests);
+      const allCallerRows = fetchCallerRows(db, node);
+      const callers = buildCallers(allCallerRows, noTests);
+      const relatedTests = buildRelatedTests(allCallerRows, getFileLines, includeTests);
       const complexityMetrics = getComplexityMetrics(db, node.id);
       const nodeChildren = getNodeChildrenSafe(db, node.id);
       const implInfo = buildImplementationInfo(db, node, noTests);

src/domain/analysis/dependencies.ts

@@ -7,13 +7,26 @@ import {
   findNodesByFile,
   openReadonlyOrFail,
 } from '../../db/index.js';
+import { cachedStmt } from '../../db/repository/cached-stmt.js';
 import { isTestFile } from '../../infrastructure/test-filter.js';
 import { resolveMethodViaHierarchy } from '../../shared/hierarchy.js';
 import { normalizeSymbol } from '../../shared/normalize.js';
 import { paginateResult } from '../../shared/paginate.js';
-import type { BetterSqlite3Database, ImportEdgeRow, NodeRow, RelatedNodeRow } from '../../types.js';
+import type {
+  BetterSqlite3Database,
+  ImportEdgeRow,
+  NodeRow,
+  RelatedNodeRow,
+  StmtCache,
+} from '../../types.js';
 import { findMatchingNodes } from './symbol-lookup.js';
 
+type UpstreamRow = { id: number; name: string; kind: string; file: string; line: number };
+type NodeByIdRow = { name: string; kind: string; file: string; line: number };
+
+const _upstreamStmtCache: StmtCache<UpstreamRow> = new WeakMap();
+const _nodeByIdStmtCache: StmtCache<NodeByIdRow> = new WeakMap();
+
 export function fileDepsData(
   file: string,
   customDbPath: string,
@@ -71,11 +84,15 @@ function buildTransitiveCallers(
   const visited = new Set([nodeId]);
   let frontier = callers;
 
-  const upstreamStmt = db.prepare(`
+  const upstreamStmt = cachedStmt(
+    _upstreamStmtCache,
+    db,
+    `
     SELECT n.id, n.name, n.kind, n.file, n.line
     FROM edges e JOIN nodes n ON e.source_id = n.id
     WHERE e.target_id = ? AND e.kind = 'calls'
-  `);
+  `,
+  );
 
   for (let d = 2; d <= depth; d++) {
     const nextFrontier: typeof frontier = [];
@@ -328,8 +345,12 @@ function reconstructPath(
   pathIds: number[],
   parent: Map<number, { parentId: number; edgeKind: string }>,
 ) {
-  const nodeCache = new Map<number, { name: string; kind: string; file: string; line: number }>();
-  const nodeByIdStmt = db.prepare('SELECT name, kind, file, line FROM nodes WHERE id = ?');
+  const nodeCache = new Map<number, NodeByIdRow>();
+  const nodeByIdStmt = cachedStmt(
+    _nodeByIdStmtCache,
+    db,
+    'SELECT name, kind, file, line FROM nodes WHERE id = ?',
+  );
   const getNode = (id: number) => {
     if (nodeCache.has(id)) return nodeCache.get(id)!;
     const row = nodeByIdStmt.get(id) as {

src/domain/analysis/impact.ts

@@ -10,6 +10,7 @@ import {
   findNodeById,
   openReadonlyOrFail,
 } from '../../db/index.js';
+import { cachedStmt } from '../../db/repository/cached-stmt.js';
 import { evaluateBoundaries } from '../../features/boundaries.js';
 import { coChangeForFiles } from '../../features/cochange.js';
 import { ownersForFiles } from '../../features/owners.js';
@@ -18,9 +19,11 @@ import { debug } from '../../infrastructure/logger.js';
 import { isTestFile } from '../../infrastructure/test-filter.js';
 import { normalizeSymbol } from '../../shared/normalize.js';
 import { paginateResult } from '../../shared/paginate.js';
-import type { BetterSqlite3Database, NodeRow, RelatedNodeRow } from '../../types.js';
+import type { BetterSqlite3Database, NodeRow, RelatedNodeRow, StmtCache } from '../../types.js';
 import { findMatchingNodes } from './symbol-lookup.js';
 
+const _defsStmtCache: StmtCache<NodeRow> = new WeakMap();
+
 // --- Shared BFS: transitive callers ---
 
 const INTERFACE_LIKE_KINDS = new Set(['interface', 'trait']);
@@ -338,7 +341,9 @@ function findAffectedFunctions(
   noTests: boolean,
 ): NodeRow[] {
   const affectedFunctions: NodeRow[] = [];
-  const defsStmt = db.prepare(
+  const defsStmt = cachedStmt(
+    _defsStmtCache,
+    db,
     `SELECT * FROM nodes WHERE file = ? AND kind IN ('function', 'method', 'class') ORDER BY line`,
   );
   for (const [file, ranges] of changedRanges) {

src/domain/analysis/roles.ts

@@ -51,7 +51,9 @@ export function rolesData(
 
     const summary: Record<string, number> = {};
     for (const r of rows) {
-      summary[r.role as string] = (summary[r.role as string] || 0) + 1;
+      // SQL guarantees role IS NOT NULL
+      const role = r.role as string;
+      summary[role] = (summary[role] || 0) + 1;
     }
 
     const hc = new Map();