codegraph/src/resolution/index.ts

/**
 * Reference Resolution Orchestrator
 *
 * Coordinates all reference resolution strategies.
 */

import * as fs from 'fs';
import * as path from 'path';
import { Node, UnresolvedReference, Edge } from '../types';
import { QueryBuilder } from '../db/queries';
import {
  UnresolvedRef,
  ResolvedRef,
  ResolutionResult,
  ResolutionContext,
  FrameworkResolver,
  ImportMapping,
} from './types';
import { matchReference, matchFunctionRef, matchDottedCallChain, matchScopedCallChain, sameLanguageFamily, crossesKnownFamily } from './name-matcher';
import { resolveViaImport, resolveJvmImport, extractImportMappings, extractReExports, loadCppIncludeDirs, isPhpIncludePathRef } from './import-resolver';
import { detectFrameworks } from './frameworks';
import { synthesizeCallbackEdges } from './callback-synthesizer';
import { createYielder, type MaybeYield } from './cooperative-yield';
import { loadProjectAliases, type AliasMap } from './path-aliases';
import { loadGoModule, type GoModule } from './go-module';
import { loadWorkspacePackages, type WorkspacePackages } from './workspace-packages';
import { logDebug } from '../errors';
import type { ReExport } from './types';
import { LRUCache } from './lru-cache';

/** Node kinds that can declare supertypes (extends/implements). */
const SUPERTYPE_BEARING_KINDS = new Set<Node['kind']>([
  'class', 'struct', 'interface', 'trait', 'protocol', 'enum',
]);

/**
 * Languages whose chained static-factory/fluent calls defer to the conformance
 * second pass. Dotted-receiver languages resolve via matchDottedCallChain; the
 * `::`-receiver ones (Rust) via matchScopedCallChain.
 */
const CHAIN_LANGUAGES = new Set(['java', 'kotlin', 'csharp', 'swift', 'rust', 'go', 'scala', 'dart', 'objc', 'pascal']);
const SCOPED_CHAIN_LANGUAGES = new Set(['rust']);

/** The extractor's chained-receiver encoding: `<inner>().<method>`. */
const CHAIN_SHAPE = /^(.+)\(\)\.(\w+)$/;

/**
 * Cache size limits. Each per-resolver cache is bounded so memory
 * stays flat on large codebases (20k+ files). Sizes were chosen to
 * cover the working set for typical resolution batches without
 * exceeding a few hundred MB worst-case. Override via the env var
 * `CODEGRAPH_RESOLVER_CACHE_SIZE` (single integer applied to all
 * caches) when tuning for very large or very small projects.
 */
const DEFAULT_CACHE_LIMIT = 5_000;
function resolveCacheLimit(): number {
  const raw = process.env.CODEGRAPH_RESOLVER_CACHE_SIZE;
  if (!raw) return DEFAULT_CACHE_LIMIT;
  const parsed = Number.parseInt(raw, 10);
  if (Number.isFinite(parsed) && parsed > 0) return parsed;
  return DEFAULT_CACHE_LIMIT;
}

// Re-export types
export * from './types';

// Pre-built Sets for O(1) built-in lookups (allocated once, shared across all instances)
const JS_BUILT_INS = new Set([
  'console', 'window', 'document', 'global', 'process',
  'Promise', 'Array', 'Object', 'String', 'Number', 'Boolean',
  'Date', 'Math', 'JSON', 'RegExp', 'Error', 'Map', 'Set',
  'setTimeout', 'setInterval', 'clearTimeout', 'clearInterval',
  'fetch', 'require', 'module', 'exports', '__dirname', '__filename',
]);

const REACT_HOOKS = new Set([
  'useState', 'useEffect', 'useContext', 'useReducer', 'useCallback',
  'useMemo', 'useRef', 'useLayoutEffect', 'useImperativeHandle', 'useDebugValue',
]);

const PYTHON_BUILT_INS = new Set([
  'print', 'len', 'range', 'str', 'int', 'float', 'list', 'dict', 'set', 'tuple',
  'open', 'input', 'type', 'isinstance', 'hasattr', 'getattr', 'setattr',
  'super', 'self', 'cls', 'None', 'True', 'False',
]);

const PYTHON_BUILT_IN_TYPES = new Set([
  'list', 'dict', 'set', 'tuple', 'str', 'int', 'float', 'bool',
  'bytes', 'bytearray', 'frozenset', 'object', 'super',
]);

const PYTHON_BUILT_IN_METHODS = new Set([
  'append', 'extend', 'insert', 'remove', 'pop', 'clear', 'sort', 'reverse', 'copy',
  'update', 'keys', 'values', 'items', 'get',
  'add', 'discard', 'union', 'intersection', 'difference',
  'split', 'join', 'strip', 'lstrip', 'rstrip', 'replace', 'lower', 'upper',
  'startswith', 'endswith', 'find', 'index', 'count', 'encode', 'decode',
  'format', 'isdigit', 'isalpha', 'isalnum',
  'read', 'write', 'readline', 'readlines', 'close', 'flush', 'seek',
]);

const GO_STDLIB_PACKAGES = new Set([
  'fmt', 'os', 'io', 'net', 'http', 'log', 'math', 'sort', 'sync',
  'time', 'path', 'bytes', 'strings', 'strconv', 'errors', 'context',
  'json', 'xml', 'csv', 'html', 'template', 'regexp', 'reflect',
  'runtime', 'testing', 'flag', 'bufio', 'crypto', 'encoding',
  'filepath', 'hash', 'mime', 'rand', 'signal', 'sql', 'syscall',
  'unicode', 'unsafe', 'atomic', 'binary', 'debug', 'exec', 'heap',
  'ring', 'scanner', 'tar', 'zip', 'gzip', 'zlib', 'tls', 'url',
  'user', 'pprof', 'trace', 'ast', 'build', 'parser', 'printer',
  'token', 'types', 'cgo', 'plugin', 'race', 'ioutil',
  // Kubernetes-common stdlib aliases
  'utilruntime', 'utilwait', 'utilnet',
]);

const GO_BUILT_INS = new Set([
  'make', 'new', 'len', 'cap', 'append', 'copy', 'delete', 'close',
  'panic', 'recover', 'print', 'println', 'complex', 'real', 'imag',
  'error', 'nil', 'true', 'false', 'iota',
  'int', 'int8', 'int16', 'int32', 'int64',
  'uint', 'uint8', 'uint16', 'uint32', 'uint64', 'uintptr',
  'float32', 'float64', 'complex64', 'complex128',
  'string', 'bool', 'byte', 'rune', 'any',
]);

const PASCAL_UNIT_PREFIXES = [
  'System.', 'Winapi.', 'Vcl.', 'Fmx.', 'Data.', 'Datasnap.',
  'Soap.', 'Xml.', 'Web.', 'REST.', 'FireDAC.', 'IBX.',
  'IdHTTP', 'IdTCP', 'IdSSL',
];

const PASCAL_BUILT_INS = new Set([
  'System', 'SysUtils', 'Classes', 'Types', 'Variants', 'StrUtils',
  'Math', 'DateUtils', 'IOUtils', 'Generics.Collections', 'Generics.Defaults',
  'Rtti', 'TypInfo', 'SyncObjs', 'RegularExpressions',
  'SysInit', 'Windows', 'Messages', 'Graphics', 'Controls', 'Forms',
  'Dialogs', 'StdCtrls', 'ExtCtrls', 'ComCtrls', 'Menus', 'ActnList',
  'WriteLn', 'Write', 'ReadLn', 'Read', 'Inc', 'Dec', 'Ord', 'Chr',
  'Length', 'SetLength', 'High', 'Low', 'Assigned', 'FreeAndNil',
  'Format', 'IntToStr', 'StrToInt', 'FloatToStr', 'StrToFloat',
  'Trim', 'UpperCase', 'LowerCase', 'Pos', 'Copy', 'Delete', 'Insert',
  'Now', 'Date', 'Time', 'DateToStr', 'StrToDate',
  'Raise', 'Exit', 'Break', 'Continue', 'Abort',
  'True', 'False', 'nil', 'Self', 'Result',
  'Create', 'Destroy', 'Free',
  'TObject', 'TComponent', 'TPersistent', 'TInterfacedObject',
  'TList', 'TStringList', 'TStrings', 'TStream', 'TMemoryStream', 'TFileStream',
  'Exception', 'EAbort', 'EConvertError', 'EAccessViolation',
  'IInterface', 'IUnknown',
]);

const C_BUILT_INS = new Set([
  // Standard C library functions
  'printf', 'fprintf', 'sprintf', 'snprintf', 'scanf', 'fscanf', 'sscanf',
  'malloc', 'calloc', 'realloc', 'free',
  'memcpy', 'memmove', 'memset', 'memcmp', 'memchr',
  'strlen', 'strcpy', 'strncpy', 'strcat', 'strncat', 'strcmp', 'strncmp',
  'strstr', 'strchr', 'strrchr', 'strtok', 'strdup',
  'fopen', 'fclose', 'fread', 'fwrite', 'fgets', 'fputs', 'fputc', 'fgetc',
  'feof', 'ferror', 'fflush', 'fseek', 'ftell', 'rewind',
  'exit', 'abort', 'atexit', 'atoi', 'atol', 'atof', 'strtol', 'strtoul', 'strtod',
  'qsort', 'bsearch',
  'abs', 'labs', 'rand', 'srand',
  'sin', 'cos', 'tan', 'sqrt', 'pow', 'log', 'log10', 'exp', 'ceil', 'floor', 'fabs',
  'time', 'clock', 'difftime', 'mktime', 'localtime', 'gmtime', 'strftime', 'asctime',
  'assert', 'errno',
  'perror', 'remove', 'rename', 'tmpfile', 'tmpnam',
  'getenv', 'system',
  'signal', 'raise',
  'setjmp', 'longjmp',
  'va_start', 'va_end', 'va_arg', 'va_copy',
  'NULL', 'EOF', 'BUFSIZ', 'FILENAME_MAX', 'RAND_MAX', 'EXIT_SUCCESS', 'EXIT_FAILURE',
  'size_t', 'ptrdiff_t', 'wchar_t', 'intptr_t', 'uintptr_t',
  'int8_t', 'int16_t', 'int32_t', 'int64_t',
  'uint8_t', 'uint16_t', 'uint32_t', 'uint64_t',
  'FILE',
  // POSIX additions commonly seen
  'stat', 'lstat', 'fstat', 'open', 'close', 'read', 'write', 'pipe',
  'fork', 'exec', 'waitpid', 'getpid', 'getppid', 'kill', 'sleep', 'usleep',
  'pthread_create', 'pthread_join', 'pthread_mutex_lock', 'pthread_mutex_unlock',
  'dlopen', 'dlsym', 'dlclose',
]);

const CPP_BUILT_INS = new Set([
  // iostream objects (often used without std:: prefix via using)
  'cout', 'cin', 'cerr', 'clog', 'endl', 'flush', 'ws',
  'std', // the namespace itself when used as std::something
  // Common C++ keywords that leak as references
  'nullptr', 'true', 'false', 'this', 'sizeof', 'alignof', 'typeid',
  'static_cast', 'dynamic_cast', 'reinterpret_cast', 'const_cast',
  'make_unique', 'make_shared', 'make_pair',
  'move', 'forward', 'swap',
]);

/**
 * Reference Resolver
 *
 * Orchestrates reference resolution using multiple strategies.
 */
export class ReferenceResolver {
  private projectRoot: string;
  private queries: QueryBuilder;
  private context: ResolutionContext;
  private frameworks: FrameworkResolver[] = [];
  // Chained static-factory/fluent call refs the first pass couldn't resolve,
  // collected in-memory (the batched resolver deletes unresolved refs from the
  // DB, so they can't be re-read). Drained by resolveChainedCallsViaConformance
  // once implements/extends edges exist, to resolve methods on a supertype the
  // receiver conforms to (#750).
  private deferredChainRefs: UnresolvedRef[] = [];
  // `this.<member>` function-as-value refs whose member is NOT on the
  // enclosing class itself — possibly inherited. Collected in-memory for the
  // same reason as deferredChainRefs and drained by
  // resolveDeferredThisMemberRefs once implements/extends edges exist (#808).
  private deferredThisMemberRefs: UnresolvedRef[] = [];
  // Per-`.razor`/`.cshtml`-file `@using` namespace set (own directives + folder
  // `_Imports.razor`, cascading to the project root). Used to disambiguate a
  // markup type ref to the right C# namespace.
  private razorUsingsCache = new Map<string, string[]>();
  // All per-resolver caches are LRU-bounded. Previously these were
  // unbounded Maps that grew with every distinct lookup and OOM'd on
  // codebases with 20k+ files (see issue: unbounded cache growth).
  private nodeCache: LRUCache<string, Node[]>; // per-file node cache
  private fileCache: LRUCache<string, string | null>; // per-file content cache
  private importMappingCache: LRUCache<string, ImportMapping[]>;
  private reExportCache: LRUCache<string, ReExport[]>;
  private nameCache: LRUCache<string, Node[]>; // name → nodes cache
  private lowerNameCache: LRUCache<string, Node[]>; // lower(name) → nodes cache
  private qualifiedNameCache: LRUCache<string, Node[]>; // qualified_name → nodes cache
  private knownNames: Set<string> | null = null; // all known symbol names for fast pre-filtering
  private knownFiles: Set<string> | null = null;
  private cachesWarmed = false;
  // tsconfig/jsconfig path-alias map. `undefined` = not yet computed,
  // `null` = computed and absent. Treated as immutable for the
  // resolver's lifetime; callers re-create the resolver if config changes.
  private projectAliases: AliasMap | null | undefined = undefined;
  // go.mod module path. Same lazy/immutable convention as projectAliases.
  private goModule: GoModule | null | undefined = undefined;
  // Monorepo workspace member packages. Same lazy/immutable convention.
  private workspacePackages: WorkspacePackages | null | undefined = undefined;

  constructor(projectRoot: string, queries: QueryBuilder) {
    this.projectRoot = projectRoot;
    this.queries = queries;

    const limit = resolveCacheLimit();
    // The content cache is heavier (full file text), so we give it a
    // smaller budget than the metadata caches.
    const contentLimit = Math.max(64, Math.floor(limit / 5));
    this.nodeCache = new LRUCache(limit);
    this.fileCache = new LRUCache(contentLimit);
    this.importMappingCache = new LRUCache(limit);
    this.reExportCache = new LRUCache(limit);
    this.nameCache = new LRUCache(limit);
    this.lowerNameCache = new LRUCache(limit);
    this.qualifiedNameCache = new LRUCache(limit);

    this.context = this.createContext();
  }

  /**
   * Initialize the resolver (detect frameworks, etc.)
   */
  initialize(): void {
    this.frameworks = detectFrameworks(this.context);
    this.clearCaches();
  }

  /**
   * Run each framework resolver's cross-file finalization pass and persist
   * the returned node updates. Idempotent — safe to call after every indexAll
   * and every incremental sync. Returns the number of nodes updated.
   *
   * Caches are cleared before/after so the post-extract pass sees fresh DB
   * state and downstream queries see the updated names.
   */
  runPostExtract(): number {
    let updated = 0;
    this.clearCaches();
    for (const fw of this.frameworks) {
      if (!fw.postExtract) continue;
      try {
        const nodes = fw.postExtract(this.context);
        for (const node of nodes) {
          this.queries.updateNode(node);
          updated++;
        }
      } catch (err) {
        logDebug(`Framework '${fw.name}' postExtract failed`, {
          error: err instanceof Error ? err.message : String(err),
        });
      }
    }
    if (updated > 0) this.clearCaches();
    return updated;
  }

  /**
   * Pre-build lightweight caches for resolution.
   * Node lookups are now handled by indexed SQLite queries instead of
   * loading all nodes into memory (which caused OOM on large codebases).
   * We cache the set of known symbol names for fast pre-filtering.
   */
  warmCaches(): void {
    if (this.cachesWarmed) return;

    // Only cache the set of known file paths (lightweight string set)
    this.knownFiles = new Set(this.queries.getAllFilePaths());

    // Cache all distinct symbol names for fast pre-filtering (just strings, not full nodes)
    this.knownNames = new Set(this.queries.getAllNodeNames());

    this.cachesWarmed = true;
  }

  /**
   * Clear internal caches
   */
  clearCaches(): void {
    this.nodeCache.clear();
    this.fileCache.clear();
    this.importMappingCache.clear();
    this.reExportCache.clear();
    this.nameCache.clear();
    this.lowerNameCache.clear();
    this.qualifiedNameCache.clear();
    this.knownNames = null;
    this.knownFiles = null;
    this.cachesWarmed = false;
  }

  /**
   * Create the resolution context
   */
  private createContext(): ResolutionContext {
    return {
      getNodesInFile: (filePath: string) => {
        if (!this.nodeCache.has(filePath)) {
          this.nodeCache.set(filePath, this.queries.getNodesByFile(filePath));
        }
        return this.nodeCache.get(filePath)!;
      },

      getNodesByName: (name: string) => {
        const cached = this.nameCache.get(name);
        if (cached !== undefined) return cached;
        const result = this.queries.getNodesByName(name);
        this.nameCache.set(name, result);
        return result;
      },

      getNodesByQualifiedName: (qualifiedName: string) => {
        const cached = this.qualifiedNameCache.get(qualifiedName);
        if (cached !== undefined) return cached;
        const result = this.queries.getNodesByQualifiedNameExact(qualifiedName);
        this.qualifiedNameCache.set(qualifiedName, result);
        return result;
      },

      getNodesByKind: (kind: Node['kind']) => {
        return this.queries.getNodesByKind(kind);
      },

      fileExists: (filePath: string) => {
        // Check pre-built known files set first (O(1))
        if (this.knownFiles) {
          const normalized = filePath.replace(/\\/g, '/');
          if (this.knownFiles.has(filePath) || this.knownFiles.has(normalized)) {
            return true;
          }
        }
        // Fall back to filesystem for files not yet indexed
        const fullPath = path.join(this.projectRoot, filePath);
        try {
          return fs.existsSync(fullPath);
        } catch (error) {
          logDebug('Error checking file existence', { filePath, error: String(error) });
          return false;
        }
      },

      readFile: (filePath: string) => {
        if (this.fileCache.has(filePath)) {
          return this.fileCache.get(filePath)!;
        }

        const fullPath = path.join(this.projectRoot, filePath);
        try {
          const content = fs.readFileSync(fullPath, 'utf-8');
          this.fileCache.set(filePath, content);
          return content;
        } catch (error) {
          logDebug('Failed to read file for resolution', { filePath, error: String(error) });
          this.fileCache.set(filePath, null);
          return null;
        }
      },

      getProjectRoot: () => this.projectRoot,

      getAllFiles: () => {
        return this.queries.getAllFilePaths();
      },

      listDirectories: (relativePath: string) => {
        const target = relativePath === '.' || relativePath === ''
          ? this.projectRoot
          : path.join(this.projectRoot, relativePath);
        try {
          return fs
            .readdirSync(target, { withFileTypes: true })
            .filter((entry) => entry.isDirectory())
            .map((entry) => entry.name);
        } catch (error) {
          logDebug('Failed to list directory for resolution', {
            relativePath,
            error: String(error),
          });
          return [];
        }
      },

      getNodesByLowerName: (lowerName: string) => {
        const cached = this.lowerNameCache.get(lowerName);
        if (cached !== undefined) return cached;
        const result = this.queries.getNodesByLowerName(lowerName);
        this.lowerNameCache.set(lowerName, result);
        return result;
      },

      getNodeById: (id: string) => {
        return this.queries.getNodeById(id);
      },

      getSupertypes: (typeName: string, language) => {
        // Union the `implements`/`extends` targets of every same-named type node.
        // Matching by simple name (not id) reconciles a type declared in one node
        // (`KF::Builder`) with conformance declared in a separate extension node
        // (`KF.Builder: KFOptionSetter`) — both have name `Builder`.
        const typeNodes = this.context
          .getNodesByName(typeName)
          .filter((n) => SUPERTYPE_BEARING_KINDS.has(n.kind) && n.language === language);
        if (typeNodes.length === 0) return [];
        const supertypes = new Set<string>();
        for (const tn of typeNodes) {
          for (const edge of this.queries.getOutgoingEdges(tn.id, ['implements', 'extends'])) {
            const target = this.queries.getNodeById(edge.target);
            if (target?.name && target.name !== typeName) supertypes.add(target.name);
          }
        }
        return [...supertypes];
      },

      getImportMappings: (filePath: string, language) => {
        const cacheKey = filePath;
        const cached = this.importMappingCache.get(cacheKey);
        if (cached) return cached;

        const content = this.context.readFile(filePath);
        if (!content) {
          this.importMappingCache.set(cacheKey, []);
          return [];
        }

        const mappings = extractImportMappings(filePath, content, language);
        this.importMappingCache.set(cacheKey, mappings);
        return mappings;
      },

      getProjectAliases: () => {
        if (this.projectAliases === undefined) {
          this.projectAliases = loadProjectAliases(this.projectRoot);
        }
        return this.projectAliases;
      },

      getGoModule: () => {
        if (this.goModule === undefined) {
          this.goModule = loadGoModule(this.projectRoot);
        }
        return this.goModule;
      },

      getWorkspacePackages: () => {
        if (this.workspacePackages === undefined) {
          this.workspacePackages = loadWorkspacePackages(this.projectRoot);
        }
        return this.workspacePackages;
      },

      getReExports: (filePath: string, language) => {
        const cached = this.reExportCache.get(filePath);
        if (cached) return cached;
        const content = this.context.readFile(filePath);
        if (!content) {
          this.reExportCache.set(filePath, []);
          return [];
        }
        // Re-exports are a JS/TS-only construct, and what matters is the
        // BARREL file's own language — not the consuming reference's. A
        // `.svelte`/`.vue` consumer threads its own language down the
        // re-export chase, which would make extractReExports() bail on a
        // `.ts` index barrel and silently break the chain (#629). Re-key
        // the parse on the barrel's extension so the chase works no matter
        // what kind of file imports through it.
        const isJsFamily = /\.(?:d\.ts|[cm]?tsx?|[cm]?jsx?)$/i.test(filePath);
        const reExports = extractReExports(content, isJsFamily ? 'typescript' : language);
        this.reExportCache.set(filePath, reExports);
        return reExports;
      },

      getCppIncludeDirs: () => {
        return loadCppIncludeDirs(this.projectRoot);
      },
    };
  }

  /**
   * Resolve all unresolved references
   */
  resolveAll(
    unresolvedRefs: UnresolvedReference[],
    onProgress?: (current: number, total: number) => void
  ): ResolutionResult {
    // Pre-load all nodes into memory for fast lookups
    this.warmCaches();

    const resolved: ResolvedRef[] = [];
    const unresolved: UnresolvedRef[] = [];
    const byMethod: Record<string, number> = {};

    // Convert to our internal format, using denormalized fields when available
    const refs: UnresolvedRef[] = unresolvedRefs.map((ref) => ({
      fromNodeId: ref.fromNodeId,
      referenceName: ref.referenceName,
      referenceKind: ref.referenceKind,
      line: ref.line,
      column: ref.column,
      filePath: ref.filePath || this.getFilePathFromNodeId(ref.fromNodeId),
      language: ref.language || this.getLanguageFromNodeId(ref.fromNodeId),
    }));

    const total = refs.length;
    let lastReportedPercent = -1;

    for (let i = 0; i < refs.length; i++) {
      const ref = refs[i]!; // Array index is guaranteed to be in bounds
      const result = this.resolveOne(ref);

      if (result) {
        resolved.push(result);
        byMethod[result.resolvedBy] = (byMethod[result.resolvedBy] || 0) + 1;
      } else {
        unresolved.push(ref);
      }

      // Report progress every 1% to avoid too many updates
      if (onProgress) {
        const currentPercent = Math.floor((i / total) * 100);
        if (currentPercent > lastReportedPercent) {
          lastReportedPercent = currentPercent;
          onProgress(i + 1, total);
        }
      }
    }

    // Final progress report
    if (onProgress && total > 0) {
      onProgress(total, total);
    }

    return {
      resolved,
      unresolved,
      stats: {
        total: refs.length,
        resolved: resolved.length,
        unresolved: unresolved.length,
        byMethod,
      },
    };
  }

  /**
   * Check if a reference name has any possible match in the codebase.
   * Uses the pre-built knownNames set to skip expensive resolution
   * for names that definitely don't exist as symbols.
   */
  private hasAnyPossibleMatch(name: string): boolean {
    if (!this.knownNames) return true; // no pre-filter available

    // Direct name match
    if (this.knownNames.has(name)) return true;

    // For qualified names like "obj.method" or "Class::method", check the parts
    const dotIdx = name.indexOf('.');
    if (dotIdx > 0) {
      const receiver = name.substring(0, dotIdx);
      const member = name.substring(dotIdx + 1);
      if (this.knownNames.has(receiver) || this.knownNames.has(member)) return true;
      // Also check capitalized receiver (instance-method resolution)
      const capitalized = receiver.charAt(0).toUpperCase() + receiver.slice(1);
      if (this.knownNames.has(capitalized)) return true;
      // JVM FQN: `com.example.foo.Bar` — the only useful segment is the
      // last one (`Bar`); the earlier check finds `example.foo.Bar` which
      // never matches a node name.
      const lastDot = name.lastIndexOf('.');
      if (lastDot > dotIdx) {
        const tail = name.substring(lastDot + 1);
        if (tail && this.knownNames.has(tail)) return true;
      }
    }
    const colonIdx = name.indexOf('::');
    if (colonIdx > 0) {
      const receiver = name.substring(0, colonIdx);
      const member = name.substring(colonIdx + 2);
      if (this.knownNames.has(receiver) || this.knownNames.has(member)) return true;
      // Multi-segment path `a::b::c` (a Rust/C++ module call like
      // `database::profiles::find`) — the only segment that names a symbol is
      // the last (`c`); `member` above is `b::c`, which never matches a node
      // name, so without this the pre-filter drops the ref before the Rust path
      // resolver ever sees it. Mirror the dotted-name leaf check above.
      const lastColon = name.lastIndexOf('::');
      if (lastColon > colonIdx) {
        const tail = name.substring(lastColon + 2);
        if (tail && this.knownNames.has(tail)) return true;
      }
    }

    // Lua/Luau method calls use a single `:` (`lg:log`); R uses `$` (`lg$log`).
    // Check the member (and receiver) around these separators too, so the ref
    // isn't dropped here before the method-call resolver ever sees it. The `:`
    // case is skipped when the name actually contains `::` (handled above).
    for (const sep of [':', '$']) {
      if (sep === ':' && name.includes('::')) continue;
      const sepIdx = name.indexOf(sep);
      if (sepIdx > 0) {
        const receiver = name.substring(0, sepIdx);
        const member = name.substring(sepIdx + 1);
        if (this.knownNames.has(member) || this.knownNames.has(receiver)) return true;
        const capitalized = receiver.charAt(0).toUpperCase() + receiver.slice(1);
        if (this.knownNames.has(capitalized)) return true;
      }
    }

    // For path-like references (e.g., "snippets/drawer-menu.liquid"), check the filename
    const slashIdx = name.lastIndexOf('/');
    if (slashIdx > 0) {
      const fileName = name.substring(slashIdx + 1);
      if (this.knownNames.has(fileName)) return true;
    }

    return false;
  }

  /**
   * Does `ref.referenceName` match an import declared in its containing
   * file? Used as a pre-filter escape so re-export chain resolution
   * still gets a chance when the name has no project-wide declaration.
   */
  private matchesAnyImport(ref: UnresolvedRef): boolean {
    const imports = this.context.getImportMappings(ref.filePath, ref.language);
    if (imports.length === 0) return false;
    for (const imp of imports) {
      if (
        imp.localName === ref.referenceName ||
        ref.referenceName.startsWith(imp.localName + '.')
      ) {
        return true;
      }
    }
    return false;
  }

  /**
   * Resolve a single reference
   */
  resolveOne(ref: UnresolvedRef): ResolvedRef | null {
    // Skip built-in/external references
    if (this.isBuiltInOrExternal(ref)) {
      return null;
    }

    // Fast pre-filter: skip if no symbol with this name exists anywhere
    // AND the name doesn't match a local import. The import escape is
    // necessary because re-export rename chains (`import { login }
    // from './barrel'` where the barrel has `export { signIn as login }
    // from './auth'`) intentionally call a name that has no
    // declaration anywhere — only the renamed upstream symbol does.
    if (
      !this.hasAnyPossibleMatch(ref.referenceName) &&
      !this.matchesAnyImport(ref) &&
      !this.frameworks.some((f) => f.claimsReference?.(ref.referenceName))
    ) {
      return null;
    }

    // Function-as-value refs (#756) get a dedicated, strictly-gated path:
    // import-based resolution first (an imported callback resolves through its
    // import, the most precise cross-file signal), then matchFunctionRef
    // (same-file first, unique-only cross-file, function/method targets only).
    // They never reach the framework or fuzzy strategies below.
    if (ref.referenceKind === 'function_ref') {
      // `this.<member>` values (TS/JS) resolve ONLY against the enclosing
      // class's own members — never a same-named symbol elsewhere.
      if (ref.referenceName.startsWith('this.')) {
        return this.gateLanguage(this.resolveThisMemberFnRef(ref), ref);
      }
      const viaImport = this.gateLanguage(resolveViaImport(ref, this.context), ref);
      if (viaImport) {
        const target = this.queries.getNodeById(viaImport.targetNodeId);
        if (target && (target.kind === 'function' || target.kind === 'method')) {
          return viaImport;
        }
      }
      return this.gateLanguage(matchFunctionRef(ref, this.context), ref);
    }

    // JVM FQN imports skip framework/name-matcher: `import com.example.Bar`
    // resolves directly through the qualifiedName index, which is unambiguous
    // even when several `Bar` classes exist in different packages.
    const jvmImport = resolveJvmImport(ref, this.context);
    if (jvmImport) return jvmImport;

    // Razor/Blazor: a markup or `@code` type ref resolves through the file's
    // `@using` namespaces (incl. folder `_Imports.razor`). This precisely
    // disambiguates a simple name that exists in several namespaces — e.g.
    // `CatalogBrand` resolving to `BlazorShared.Models::CatalogBrand` (the DTO,
    // which the `.razor` `@using`s) rather than the same-named domain entity.
    if (ref.language === 'razor') {
      const razorResult = this.resolveRazorUsing(ref);
      if (razorResult) return razorResult;
    }

    const candidates: ResolvedRef[] = [];

    // Strategy 1: Try framework-specific resolution. Cross-language bridges
    // are deliberately preserved (Drupal `routing.yml` → PHP controller, RN
    // JS → native `calls`) — `gateFrameworkLanguage` only drops a type/import
    // edge between two KNOWN families (see its doc), never a `calls` bridge or
    // a config↔code edge.
    for (const framework of this.frameworks) {
      const result = this.gateFrameworkLanguage(framework.resolve(ref, this.context), ref);
      if (result) {
        if (result.confidence >= 0.9) return result; // High confidence, return immediately
        candidates.push(result);
      }
    }

    // Strategy 2: Try import-based resolution
    const importResult = this.gateLanguage(resolveViaImport(ref, this.context), ref);
    if (importResult) {
      if (importResult.confidence >= 0.9) return importResult;
      candidates.push(importResult);
    }

    // PHP include/require paths resolve to files via import resolution only.
    // If that didn't find the file, do NOT fall back to the symbol
    // name-matcher — it would mis-connect e.g. "inc/db.php" to an unrelated
    // db.php elsewhere in the tree (a wrong edge is worse than none, #660).
    if (isPhpIncludePathRef(ref)) {
      return candidates.length > 0
        ? candidates.reduce((best, curr) =>
            curr.confidence > best.confidence ? curr : best
          )
        : null;
    }

    // Strategy 3: Try name matching
    const nameResult = this.gateLanguage(matchReference(ref, this.context), ref);
    if (nameResult) {
      candidates.push(nameResult);
    }

    if (candidates.length === 0) {
      // Defer a chained static-factory/fluent call the first pass couldn't
      // resolve — its method may live on a supertype the receiver conforms to,
      // resolvable once implements/extends edges exist (the conformance pass).
      if (
        ref.referenceKind === 'calls' &&
        CHAIN_LANGUAGES.has(ref.language) &&
        CHAIN_SHAPE.test(ref.referenceName)
      ) {
        this.deferredChainRefs.push(ref);
      }
      return null;
    }

    // Return highest confidence candidate
    return candidates.reduce((best, curr) =>
      curr.confidence > best.confidence ? curr : best
    );
  }

  /**
   * Create edges from resolved references
   */
  createEdges(resolved: ResolvedRef[]): Edge[] {
    return resolved.map((ref) => {
      // `function_ref` (#756) is internal-only: it persists as a `references`
      // edge (the registration site depends on the callback), distinguishable
      // by metadata.resolvedBy === 'function-ref'. callers/impact already
      // traverse `references`, so registration sites surface with no
      // graph-layer changes.
      let kind: Edge['kind'] =
        ref.original.referenceKind === 'function_ref' ? 'references' : ref.original.referenceKind;

      // Promote "extends" to "implements" when a class/struct targets an interface
      if (kind === 'extends') {
        const targetNode = this.queries.getNodeById(ref.targetNodeId);
        if (targetNode && (targetNode.kind === 'interface' || targetNode.kind === 'protocol')) {
          const sourceNode = this.queries.getNodeById(ref.original.fromNodeId);
          if (sourceNode && sourceNode.kind !== 'interface' && sourceNode.kind !== 'protocol') {
            kind = 'implements';
          }
        }
      }

      // Promote "calls" to "instantiates" when the resolved target is a
      // class/struct. Languages without a `new` keyword (Python, Ruby)
      // express instantiation as `Foo()` — extraction can't tell that
      // apart from a function call without symbol info, but resolution
      // can: if `Foo` resolves to a class, the call IS an instantiation.
      if (kind === 'calls') {
        const targetNode = this.queries.getNodeById(ref.targetNodeId);
        if (targetNode && (targetNode.kind === 'class' || targetNode.kind === 'struct')) {
          kind = 'instantiates';
        }
      }

      return {
        source: ref.original.fromNodeId,
        target: ref.targetNodeId,
        kind,
        line: ref.original.line,
        column: ref.original.column,
        metadata: {
          confidence: ref.confidence,
          resolvedBy: ref.resolvedBy,
          // Uniform marker for function-as-value edges (#756), regardless of
          // which strategy resolved them (import vs matchFunctionRef) — lets
          // tooling label "callback registration" and lets validation diff
          // exactly the edges this feature added.
          ...(ref.original.referenceKind === 'function_ref' ? { fnRef: true } : {}),
        },
      };
    });
  }

  /**
   * Resolve and persist edges to database
   */
  resolveAndPersist(
    unresolvedRefs: UnresolvedReference[],
    onProgress?: (current: number, total: number) => void
  ): ResolutionResult {
    const result = this.resolveAll(unresolvedRefs, onProgress);

    // Create edges from resolved references
    const edges = this.createEdges(result.resolved);

    // Insert edges into database
    if (edges.length > 0) {
      this.queries.insertEdges(edges);
    }

    // Clean up resolved refs from unresolved_refs table so metrics are accurate
    if (result.resolved.length > 0) {
      this.queries.deleteSpecificResolvedReferences(
        result.resolved.map((r) => ({
          fromNodeId: r.original.fromNodeId,
          referenceName: r.original.referenceName,
          referenceKind: r.original.referenceKind,
        }))
      );
    }

    return result;
  }

  /**
   * Second resolution pass for chained static-factory / fluent calls whose
   * chained method is defined on a SUPERTYPE the receiver's type conforms to —
   * a protocol-extension / inherited / default-interface method (#750). The
   * first pass can't resolve these because `implements`/`extends` edges aren't
   * built yet; this runs AFTER edges are persisted, so `context.getSupertypes`
   * (and the conformance fallback in resolveMethodOnType) can walk them.
   *
   * Operates only on the leftover unresolved refs that have the `inner().method`
   * chain shape, for the dotted-chain languages — a small set — and is idempotent
   * (re-resolving an already-resolved ref is a no-op since it's been deleted).
   * Returns the number of newly-created edges.
   */
  async resolveChainedCallsViaConformance(): Promise<number> {
    const deferred = this.deferredChainRefs;
    this.deferredChainRefs = [];
    if (deferred.length === 0) return 0;

    // Read fresh edges (the main pass built the implements/extends edges after
    // these refs were deferred). matchDottedCallChain now resolves a method on a
    // supertype via context.getSupertypes -> resolveMethodOnType's conformance walk.
    this.clearCaches();
    // This post-pass runs synchronously on the indexer's main thread; yield
    // periodically so the #850 liveness watchdog heartbeat can fire on a repo
    // with many deferred chained calls (#1091).
    const maybeYield = createYielder();
    const resolved: ResolvedRef[] = [];
    for (const ref of deferred) {
      // `::`-receiver languages (Rust) split on `::` (matchScopedCallChain);
      // dotted-receiver languages on `.` (matchDottedCallChain).
      const chainMatch = SCOPED_CHAIN_LANGUAGES.has(ref.language)
        ? matchScopedCallChain(ref, this.context)
        : matchDottedCallChain(ref, this.context);
      const match = this.gateLanguage(chainMatch, ref);
      if (match) resolved.push(match);
      await maybeYield();
    }
    if (resolved.length === 0) return 0;

    const edges = this.createEdges(resolved);
    if (edges.length > 0) {
      this.queries.insertEdges(edges);
      this.clearCaches();
    }
    return edges.length;
  }

  /**
   * Resolve one batch in smaller sub-chunks, yielding to the event loop between
   * them so the #850 liveness heartbeat can fire on a slow/dense batch (#1091).
   * Behaviourally identical to a single `resolveAll(batch)`: `warmCaches()` is
   * idempotent (guarded) and `resolveOne` is independent per ref, so splitting
   * and re-merging changes only timing, never which edges get created. Falls
   * through to a plain `resolveAll` when the batch is already small.
   */
  private async resolveBatchYielding(
    batch: UnresolvedReference[],
    maybeYield: MaybeYield,
    subChunkSize: number = 500
  ): Promise<ResolutionResult> {
    if (batch.length <= subChunkSize) return this.resolveAll(batch);

    const resolved: ResolvedRef[] = [];
    const unresolved: UnresolvedRef[] = [];
    const byMethod: Record<string, number> = {};
    let total = 0;
    let resolvedCount = 0;
    let unresolvedCount = 0;
    for (let i = 0; i < batch.length; i += subChunkSize) {
      const chunk = this.resolveAll(batch.slice(i, i + subChunkSize));
      for (const r of chunk.resolved) resolved.push(r);
      for (const u of chunk.unresolved) unresolved.push(u);
      total += chunk.stats.total;
      resolvedCount += chunk.stats.resolved;
      unresolvedCount += chunk.stats.unresolved;
      for (const [m, c] of Object.entries(chunk.stats.byMethod)) {
        byMethod[m] = (byMethod[m] || 0) + c;
      }
      await maybeYield();
    }
    return { resolved, unresolved, stats: { total, resolved: resolvedCount, unresolved: unresolvedCount, byMethod } };
  }

  /**
   * Resolve and persist in batches to keep memory bounded.
   * Processes unresolved references in chunks, persisting edges and cleaning
   * up resolved refs after each batch to avoid accumulating large arrays.
   */
  async resolveAndPersistBatched(
    onProgress?: (current: number, total: number) => void,
    batchSize: number = 5000
  ): Promise<ResolutionResult> {
    this.warmCaches();

    // Resolution runs on the indexer's MAIN thread, and the #850 liveness
    // watchdog SIGKILLs a process whose event loop stalls past its window (60s
    // by default). A single dense batch's resolveAll — or the synthesis pass
    // below — can exceed that on a large repo, killing a VALID in-progress index
    // (#1091). A shared yielder lets both give the watchdog heartbeat a regular
    // window to fire; see ./cooperative-yield.
    const maybeYield = createYielder();

    const total = this.queries.getUnresolvedReferencesCount();
    let processed = 0;
    const aggregateStats = {
      total: 0,
      resolved: 0,
      unresolved: 0,
      byMethod: {} as Record<string, number>,
    };

    // Process in batches. We always read from offset 0 because resolved refs
    // are deleted after each batch, shifting the remaining rows forward.
    let prevRemaining = Number.POSITIVE_INFINITY;
    while (true) {
      const batch = this.queries.getUnresolvedReferencesBatch(0, batchSize);
      if (batch.length === 0) break;

      const result = await this.resolveBatchYielding(batch, maybeYield);

      // Persist edges immediately
      const edges = this.createEdges(result.resolved);
      if (edges.length > 0) {
        this.queries.insertEdges(edges);
      }

      // Clean up resolved refs so they don't appear in the next batch
      if (result.resolved.length > 0) {
        this.queries.deleteSpecificResolvedReferences(
          result.resolved.map((r) => ({
            fromNodeId: r.original.fromNodeId,
            referenceName: r.original.referenceName,
            referenceKind: r.original.referenceKind,
          }))
        );
      }

      // Delete unresolvable refs from this batch to avoid re-processing them
      if (result.unresolved.length > 0) {
        this.queries.deleteSpecificResolvedReferences(
          result.unresolved.map((r) => ({
            fromNodeId: r.fromNodeId,
            referenceName: r.referenceName,
            referenceKind: r.referenceKind,
          }))
        );
      }

      // Aggregate stats
      aggregateStats.total += result.stats.total;
      aggregateStats.resolved += result.stats.resolved;
      aggregateStats.unresolved += result.stats.unresolved;
      for (const [method, count] of Object.entries(result.stats.byMethod)) {
        aggregateStats.byMethod[method] = (aggregateStats.byMethod[method] || 0) + count;
      }

      processed += batch.length;
      onProgress?.(processed, total);

      // Yield so progress UI can render between batches
      await new Promise(resolve => setImmediate(resolve));

      // If nothing was resolved or removed in this batch, we'd loop forever
      // on the same rows. Break to avoid infinite loop.
      if (result.resolved.length === 0 && result.unresolved.length === batch.length) {
        break;
      }

      // Non-progress guard (defense-in-depth). Because we re-read from offset 0
      // each pass, the unresolved_refs table MUST shrink every iteration — both
      // resolved and unresolved refs are deleted above. If it didn't shrink, a
      // resolver returned a match whose `original.referenceName` differs from the
      // stored row, so the keyed delete no-ops, and we'd re-read + re-resolve +
      // re-insert the same rows forever (the runaway that grew a 99-file repo to
      // 5M edges / 1.4 GB before the Go-fallback fix). Stop rather than grow the
      // graph without bound.
      const remaining = this.queries.getUnresolvedReferencesCount();
      if (remaining >= prevRemaining) break;
      prevRemaining = remaining;
    }

    // Dynamic-edge synthesis: now that all base `calls` edges are persisted,
    // synthesize observer/callback dispatch edges (dispatcher → registered
    // callbacks) that static parsing leaves out. Best-effort — never fail the
    // index on it. See docs/design/callback-edge-synthesis.md.
    try {
      aggregateStats.byMethod['callback-synthesis'] = await synthesizeCallbackEdges(this.queries, this.context);
    } catch {
      // synthesis is additive and optional; ignore failures
    }

    return {
      resolved: [],
      unresolved: [],
      stats: aggregateStats,
    };
  }

  /**
   * Get detected frameworks
   */
  getDetectedFrameworks(): string[] {
    return this.frameworks.map((f) => f.name);
  }

  /**
   * Check if reference is to a built-in or external symbol
   */
  private isBuiltInOrExternal(ref: UnresolvedRef): boolean {
    const name = ref.referenceName;
    const isJsTs = ref.language === 'typescript' || ref.language === 'javascript'
      || ref.language === 'tsx' || ref.language === 'jsx';

    // JavaScript/TypeScript built-ins
    if (isJsTs && JS_BUILT_INS.has(name)) {
      return true;
    }

    // Common JS/TS library calls (console.log, Math.floor, JSON.parse)
    if (isJsTs && (name.startsWith('console.') || name.startsWith('Math.') || name.startsWith('JSON.'))) {
      return true;
    }

    // React hooks from React itself
    if (isJsTs && REACT_HOOKS.has(name)) {
      return true;
    }

    // Python built-ins (bare calls only — dotted calls like console.print are method calls)
    if (ref.language === 'python' && PYTHON_BUILT_INS.has(name)) {
      return true;
    }

    // Python built-in method calls (e.g., list.extend, dict.update)
    if (ref.language === 'python') {
      const dotIdx = name.indexOf('.');
      if (dotIdx > 0) {
        const receiver = name.substring(0, dotIdx);
        const method = name.substring(dotIdx + 1);
        // Filter calls on built-in types (list.append, dict.update, etc.)
        if (PYTHON_BUILT_IN_TYPES.has(receiver)) {
          return true;
        }
        // Filter built-in methods on non-class receivers
        // (e.g., items.append where items is a local list variable)
        // But allow if the capitalized receiver matches a known codebase class
        if (PYTHON_BUILT_IN_METHODS.has(method)) {
          const capitalized = receiver.charAt(0).toUpperCase() + receiver.slice(1);
          if (!this.knownNames?.has(capitalized)) {
            return true;
          }
        }
      }
      // A bare name colliding with a builtin method (index, get, update, count…)
      // is only a builtin when NOTHING in the codebase declares it. A declared
      // symbol with that exact name — e.g. a Flask/FastAPI view `def index()` or
      // `def get()` — is a real reference target. Mirrors the knownNames guard on
      // the dotted branch above; without it, every handler named after a builtin
      // method silently loses its route→handler edge.
      if (PYTHON_BUILT_IN_METHODS.has(name) && !this.knownNames?.has(name)) {
        return true;
      }
    }

    // Go standard library packages — refs like "fmt.Println", "http.ListenAndServe", etc.
    if (ref.language === 'go') {
      const dotIdx = name.indexOf('.');
      if (dotIdx > 0) {
        const pkg = name.substring(0, dotIdx);
        if (GO_STDLIB_PACKAGES.has(pkg)) {
          return true;
        }
      }
      if (GO_BUILT_INS.has(name)) {
        return true;
      }
    }

    // Pascal/Delphi built-ins and standard library units
    if (ref.language === 'pascal') {
      if (PASCAL_UNIT_PREFIXES.some((p) => name.startsWith(p))) {
        return true;
      }
      if (PASCAL_BUILT_INS.has(name)) {
        return true;
      }
    }

    // C/C++ standard library symbols (printf, malloc, std::vector, etc.).
    // Names that collide with user-defined symbols are NOT filtered —
    // C and C++ projects routinely shadow stdlib names (custom allocators
    // define `malloc`/`free`, stream wrappers define `read`/`write`/`open`,
    // containers define `move`/`swap`, logging libs wrap `printf`). Killing
    // those resolutions makes the graph wrong, not cleaner. We only filter
    // when there's no user node with this name — then name-matching would
    // produce zero edges anyway and the filter just short-circuits work.
    if (ref.language === 'c' || ref.language === 'cpp') {
      // C++ std:: namespace prefix — safe to filter unconditionally,
      // since `std::foo` is never a user-defined qualified name in
      // tree-sitter output.
      if (name.startsWith('std::')) return true;
      if (C_BUILT_INS.has(name) || CPP_BUILT_INS.has(name)) {
        return !this.hasAnyPossibleMatch(name);
      }
    }

    return false;
  }

  /**
   * Get file path from node ID
   */
  private getFilePathFromNodeId(nodeId: string): string {
    const node = this.queries.getNodeById(nodeId);
    return node?.filePath || '';
  }

  /**
   * Get language from node ID
   */
  private getLanguageFromNodeId(nodeId: string): UnresolvedRef['language'] {
    const node = this.queries.getNodeById(nodeId);
    return node?.language || 'unknown';
  }

  /**
   * Drop an import/name-strategy resolution that crosses a language family.
   * Two regimes (mirrors `applyLanguageGate`'s candidate filter):
   *  - `references` (type usage): STRICT — a `Type.member` static read names a
   *    same-family type, never a coincidentally same-named symbol in another
   *    language. Drops any non-same-family target.
   *  - `imports` (import binding / `#include`): both-known — a C++ `#include
   *    "X.h"` must not resolve to a same-named ObjC header on another platform
   *    (basename collision), but a singleton-family / SFC language (`vue` →
   *    `.ts`) importing across is left alone.
   * Applies to the import (strategy 2) + name-match (strategy 3) results.
   */
  /**
   * Collect the `@using` namespaces in scope for a `.razor`/`.cshtml` file: its
   * own `@using` directives plus every `_Imports.razor` from the file's folder up
   * to the project root (Razor `_Imports` cascade). Cached per file.
   */
  private getRazorUsings(filePath: string): string[] {
    const cached = this.razorUsingsCache.get(filePath);
    if (cached) return cached;
    const usings = new Set<string>();
    const addFrom = (src: string | null): void => {
      if (!src) return;
      for (const m of src.matchAll(/^\s*@using\s+(?:static\s+)?([A-Za-z_][\w.]*)/gm)) usings.add(m[1]!);
    };
    addFrom(this.context.readFile(filePath));
    let dir = filePath.includes('/') ? filePath.slice(0, filePath.lastIndexOf('/')) : '';
    // Walk up to the project root, reading each level's _Imports.razor.
    for (;;) {
      addFrom(this.context.readFile(dir ? `${dir}/_Imports.razor` : '_Imports.razor'));
      if (!dir) break;
      const slash = dir.lastIndexOf('/');
      dir = slash >= 0 ? dir.slice(0, slash) : '';
    }
    const arr = [...usings];
    this.razorUsingsCache.set(filePath, arr);
    return arr;
  }

  /**
   * Resolve a Razor/Blazor simple type ref through the file's `@using`
   * namespaces: `CatalogBrand` + `@using BlazorShared.Models` → the node whose
   * qualified name is `BlazorShared.Models::CatalogBrand`. Only resolves when the
   * `@using` set yields exactly ONE type (otherwise it stays ambiguous and falls
   * through to name-matching).
   */
  private resolveRazorUsing(ref: UnresolvedRef): ResolvedRef | null {
    if (ref.referenceName.includes('.') || ref.referenceName.includes('::')) return null;
    const usings = this.getRazorUsings(ref.filePath);
    if (usings.length === 0) return null;
    const found = new Map<string, Node>();
    for (const ns of usings) {
      for (const cand of this.context.getNodesByQualifiedName(`${ns}::${ref.referenceName}`)) {
        found.set(cand.id, cand);
      }
    }
    if (found.size !== 1) return null;
    const target = found.values().next().value!;
    return { original: ref, targetNodeId: target.id, confidence: 0.9, resolvedBy: 'import' };
  }

  /**
   * Resolve a `this.<member>` function-as-value reference (#756/#808) to the
   * ENCLOSING CLASS's own member — never a same-named symbol elsewhere. The
   * registration idiom (`btn.on('click', this.handleClick)`) names a member
   * of the class being defined, so the only valid target shares the
   * from-symbol's qualified-name scope. Function/method targets only — a
   * property (a data field, post-#808 classification) yields no edge — same
   * file required, no fallback of any kind.
   */
  private resolveThisMemberFnRef(ref: UnresolvedRef): ResolvedRef | null {
    const member = ref.referenceName.slice('this.'.length);
    if (!member) return null;
    const fromNode = this.queries.getNodeById(ref.fromNodeId);
    if (!fromNode) return null;
    // A hook declared at class-body level (Ruby `before_action :authenticate`)
    // attributes to the CLASS node itself — its qualified name IS the scope.
    // For members, strip the member segment.
    let classPrefix: string;
    if (SUPERTYPE_BEARING_KINDS.has(fromNode.kind) || fromNode.kind === 'module') {
      classPrefix = fromNode.qualifiedName;
    } else {
      const sep = fromNode.qualifiedName.lastIndexOf('::');
      if (sep <= 0) return null; // not inside a class scope
      classPrefix = fromNode.qualifiedName.slice(0, sep);
    }
    const candidates = this.context
      .getNodesByQualifiedName(`${classPrefix}::${member}`)
      .filter(
        (n) =>
          (n.kind === 'function' || n.kind === 'method') &&
          n.filePath === ref.filePath &&
          n.id !== ref.fromNodeId
      );
    if (candidates.length === 0) {
      // Not on the class itself — possibly INHERITED. implements/extends
      // edges don't exist yet in this pass, so retry in the supertype pass
      // (resolveDeferredThisMemberRefs) instead of giving up.
      this.deferredThisMemberRefs.push(ref);
      return null;
    }
    const target = candidates.reduce((a, b) => (a.startLine <= b.startLine ? a : b));
    return {
      original: ref,
      targetNodeId: target.id,
      confidence: 0.95,
      resolvedBy: 'function-ref',
    };
  }

  /**
   * Second pass for `this.<member>` refs whose member wasn't on the enclosing
   * class itself (#808): once implements/extends edges exist, walk the
   * class's supertypes (transitively, depth-capped) and resolve the member on
   * the nearest one that declares it — `this.handleSubmit` registered in a
   * subclass resolves to `FormBase::handleSubmit`. Validated targets only
   * (function/method kind, same language family); no match → no edge.
   * Mirrors resolveChainedCallsViaConformance's lifecycle. Returns the number
   * of newly-created edges.
   */
  async resolveDeferredThisMemberRefs(): Promise<number> {
    const deferred = this.deferredThisMemberRefs;
    this.deferredThisMemberRefs = [];
    if (deferred.length === 0) return 0;

    this.clearCaches();
    // Synchronous main-thread post-pass with a per-ref supertype BFS — yield
    // periodically so the #850 liveness watchdog heartbeat can fire (#1091).
    const maybeYield = createYielder();
    const resolved: ResolvedRef[] = [];
    for (const ref of deferred) {
      await maybeYield();
      const member = ref.referenceName.slice('this.'.length);
      const fromNode = this.queries.getNodeById(ref.fromNodeId);
      if (!fromNode || !member) continue;
      // Class-body-level hooks (Ruby) attribute to the CLASS node itself.
      let className: string;
      if (SUPERTYPE_BEARING_KINDS.has(fromNode.kind) || fromNode.kind === 'module') {
        className = fromNode.name;
      } else {
        const sep = fromNode.qualifiedName.lastIndexOf('::');
        if (sep <= 0) continue;
        const classPrefix = fromNode.qualifiedName.slice(0, sep);
        className = classPrefix.includes('::')
          ? classPrefix.slice(classPrefix.lastIndexOf('::') + 2)
          : classPrefix;
      }

      // NODE-anchored BFS up the supertype graph: start from the class node
      // in the ref's own file (never a same-named class elsewhere — rails has
      // a dozen `Engine`s), follow implements/extends EDGES to supertype
      // NODES, and look members up through `contains` edges. No name-based
      // unions anywhere — a name-keyed getSupertypes('Engine') merged every
      // Engine's parents and produced a cross-class wrong edge on rails.
      let frontierNodes = this.context
        .getNodesByName(className)
        .filter(
          (n) =>
            SUPERTYPE_BEARING_KINDS.has(n.kind) &&
            n.filePath === ref.filePath
        );
      if (frontierNodes.length === 0) {
        // The class itself may be declared in another file (partial/reopened
        // classes); fall back to same-family nodes of that name.
        frontierNodes = this.context
          .getNodesByName(className)
          .filter(
            (n) =>
              SUPERTYPE_BEARING_KINDS.has(n.kind) &&
              sameLanguageFamily(n.language, ref.language)
          );
      }
      const seenNodes = new Set<string>(frontierNodes.map((n) => n.id));
      let target: Node | null = null;
      for (let depth = 0; depth < 5 && frontierNodes.length > 0 && !target; depth++) {
        const next: Node[] = [];
        for (const typeNode of frontierNodes) {
          for (const edge of this.queries.getOutgoingEdges(typeNode.id, ['implements', 'extends'])) {
            const superNode = this.queries.getNodeById(edge.target);
            if (!superNode || seenNodes.has(superNode.id)) continue;
            seenNodes.add(superNode.id);
            if (!SUPERTYPE_BEARING_KINDS.has(superNode.kind)) continue;
            // Member lookup anchored on the supertype's contains edges.
            for (const c of this.queries.getOutgoingEdges(superNode.id, ['contains'])) {
              const m = this.queries.getNodeById(c.target);
              if (
                m &&
                m.name === member &&
                (m.kind === 'function' || m.kind === 'method') &&
                sameLanguageFamily(m.language, ref.language)
              ) {
                target = m;
                break;
              }
            }
            if (target) break;
            next.push(superNode);
          }
          if (target) break;
        }
        frontierNodes = next;
      }

      if (target) {
        resolved.push({
          original: ref,
          targetNodeId: target.id,
          confidence: 0.85,
          resolvedBy: 'function-ref',
        });
      }
    }
    if (resolved.length === 0) return 0;

    const edges = this.createEdges(resolved);
    if (edges.length > 0) {
      this.queries.insertEdges(edges);
      this.clearCaches();
    }
    return edges.length;
  }

  private gateLanguage(result: ResolvedRef | null, ref: UnresolvedRef): ResolvedRef | null {
    if (!result) return result;
    const tgt = this.getLanguageFromNodeId(result.targetNodeId);
    if (!tgt || !ref.language) return result;
    if ((ref.referenceKind === 'references' || ref.referenceKind === 'function_ref') && !sameLanguageFamily(tgt, ref.language)) return null;
    if (ref.referenceKind === 'imports' && crossesKnownFamily(tgt, ref.language)) return null;
    return result;
  }

  /**
   * Drop a FRAMEWORK-strategy resolution that crosses two *known* language
   * families for a type-usage (`references`) or import-binding (`imports`)
   * edge. The framework strategy is intentionally ungated for cross-language
   * bridges, but those legitimate bridges are either `calls` edges (RN/Expo
   * JS → native) or config↔code edges whose config side (`yaml`/`blade`/…) is
   * not a known programming-language family. A `references`/`imports` edge
   * between two *known* families is always a coincidental name collision — the
   * React/Svelte/Vue PascalCase component resolvers name-match `getNodesByName`
   * without a language check, so a TS `<TestRunner>` ref happily matched a
   * Kotlin `class TestRunner`. Gating only the both-known-cross-family case
   * lets config bridges and `calls` bridges through untouched.
   */
  private gateFrameworkLanguage(result: ResolvedRef | null, ref: UnresolvedRef): ResolvedRef | null {
    if (!result) return result;
    if (ref.referenceKind !== 'references' && ref.referenceKind !== 'imports') return result;
    const tgt = this.getLanguageFromNodeId(result.targetNodeId);
    if (tgt && ref.language && crossesKnownFamily(tgt, ref.language)) return null;
    return result;
  }
}

/**
 * Create a reference resolver instance
 */
export function createResolver(projectRoot: string, queries: QueryBuilder): ReferenceResolver {
  const resolver = new ReferenceResolver(projectRoot, queries);
  resolver.initialize();
  return resolver;
}