typescript-barrel-split-services

Answer

The split. Replace the 713L services/capability-router.service.ts with a 7-file module directory. The original file is deleted — the original import specifier '.../capability-router.service' then resolves to the directory's index.ts (Node/TS directory resolution), so existing imports keep working untouched:

services/
  index.ts                        ← parent barrel: export * from './capability-router.service'
  capability-router.service/
    index.ts                      ← barrel: re-exports all 6 siblings (module 7/7)
    types.ts                      ← interfaces + CapabilityList (module 1/7)
    constants.ts                  ← DEFAULT_* + __dirname path (module 2/7)
    size-utils.ts                 ← parseSize/sizeToBytes/compareSizes/computeSizeScore (3/7)
    score-utils.ts                ← computeMatchScore/scoreCandidate/rankCandidates (4/7)
    fallback.ts                   ← buildFallbackChain/applyFallback (5/7)
    core.ts                       ← class + singleton + factories (6/7)

Barrel (the "test imports all 7 via original path" trick):

// capability-router.service/index.ts
export * from './types';
export * from './constants';
export * from './size-utils';
export * from './score-utils';
export * from './fallback';
export * from './core';

KEY PATTERN — __dirname depth change. The path lives in constants.ts, one level deeper than the original file, so the leading ../ count increases 4→5 to keep the resolved absolute path byte-identical:

// BEFORE (services/capability-router.service.ts): 4 segments
export const DEFAULT_ROUTES_PATH = path.resolve(__dirname, '../../../../config/capability-routes.json');

// AFTER (services/capability-router.service/constants.ts): 5 segments
export const DEFAULT_ROUTES_PATH = path.resolve(__dirname, '../../../../../config/capability-routes.json');

core.ts holds the class, singleton, and factories; helpers are standalone with explicit params (no closure over module state):

export class CapabilityRouterService { ... }                  // class
export const capabilityRouterService = new CapabilityRouterService();  // singleton (parity)
export function createCapabilityRouterService(options?) { return new CapabilityRouterService(options); }
export function createRouterFromRoutesFile(routesPath: string) { return new CapabilityRouterService({ routesPath }); }