[BUG] tsconfig.json alias not working for extended configs #11770
Description
Describe the Bug
When the root tsconfig.json is extended from another tsconfig.json file, the compilerOptions.paths is not working. As in I can't use path aliases in Mastra files.
Steps To Reproduce
- Create a new project with
pnpm create mastra@beta - Add a new file at
.test/tsconfig.jsonwith these contents:
{
"compilerOptions": {
"paths": {
"$lib": [
"../src/lib"
],
"$lib/*": [
"../src/lib/*"
],
},
"rootDirs": [
"..",
"./types"
],
"verbatimModuleSyntax": true,
"isolatedModules": true,
"lib": [
"esnext",
"DOM",
"DOM.Iterable"
],
"moduleResolution": "bundler",
"module": "esnext",
"noEmit": true,
"target": "esnext"
},
"include": [
"ambient.d.ts",
"non-ambient.d.ts",
"./types/**/$types.d.ts",
"../src/**/*.js",
"../src/**/*.ts",
"../tests/**/*.js",
"../tests/**/*.ts",
],
"exclude": [
"../node_modules/**",
]
}- Edit the root
tsconfig.jsonto this:
{
"extends": "./.test/tsconfig.json",
"compilerOptions": {
"rewriteRelativeImportExtensions": true,
"moduleResolution": "bundler",
"resolveJsonModule": true,
"allowJs": true,
"checkJs": true,
"strict": true,
"sourceMap": true,
"esModuleInterop": true,
"forceConsistentCasingInFileNames": true,
"skipLibCheck": true
}
}- Create a
src/lib/index.tsfile with contents:export const TEST = '123' - Change
src/mastra/index.tsto this:
import { Mastra } from '@mastra/core/mastra';
import { PinoLogger } from '@mastra/loggers';
import { LibSQLStore } from '@mastra/libsql';
import { Observability } from '@mastra/observability';
import { weatherWorkflow } from './workflows/weather-workflow';
import { weatherAgent } from './agents/weather-agent';
import { TEST } from '$lib';
import { toolCallAppropriatenessScorer, completenessScorer, translationScorer } from './scorers/weather-scorer';
export const mastra = new Mastra({
workflows: { weatherWorkflow },
agents: { weatherAgent },
scorers: { toolCallAppropriatenessScorer, completenessScorer, translationScorer },
storage: new LibSQLStore({
id: "mastra-storage",
// stores observability, scores, ... into memory storage, if it needs to persist, change to file:../mastra.db
url: ":memory:",
}),
logger: new PinoLogger({
name: `Mastra ${TEST}`,
level: 'info',
}),
observability: new Observability({
// Enables DefaultExporter and CloudExporter for tracing
default: { enabled: true },
}),
});- Run
mastra dev
Error:
◐ Preparing development environment...
✓ Initial bundle complete
◇ Starting Mastra dev server...
node:internal/modules/package_json_reader:268
throw new ERR_MODULE_NOT_FOUND(packageName, fileURLToPath(base), null);
^
Error [ERR_MODULE_NOT_FOUND]: Cannot find package '$lib' imported from /Users/lejoe/code/playground/ts-paths-debug/.mastra/output/index.mjs
at Object.getPackageJSONURL (node:internal/modules/package_json_reader:268:9)
at packageResolve (node:internal/modules/esm/resolve:768:81)
at moduleResolve (node:internal/modules/esm/resolve:858:18)
at defaultResolve (node:internal/modules/esm/resolve:990:11)
at #cachedDefaultResolve (node:internal/modules/esm/loader:768:20)
at ModuleLoader.resolve (node:internal/modules/esm/loader:745:38)
at ModuleLoader.getModuleJobForImport (node:internal/modules/esm/loader:318:38)
at #link (node:internal/modules/esm/module_job:208:49)
at process.processTicksAndRejections (node:internal/process/task_queues:105:5) {
code: 'ERR_MODULE_NOT_FOUND'
}Link to Minimal Reproducible Example
Expected Behavior
Path alias works
Environment Information
System:
OS: macOS 26.2
CPU: (12) arm64 Apple M4 Pro
Memory: 2.98 GB / 48.00 GB
Shell: 5.9 - /opt/local/bin/zsh
Binaries:
Node: 24.8.0 - /Users/lejoe/.local/state/fnm_multishells/77709_1767972886475/bin/node
npm: 11.6.0 - /Users/lejoe/.local/state/fnm_multishells/77709_1767972886475/bin/npm
pnpm: 10.23.0 - /Users/lejoe/.local/state/fnm_multishells/77709_1767972886475/bin/pnpm
bun: 1.2.21 - /Users/lejoe/.bun/bin/bun
Deno: 2.5.0 - /Users/lejoe/.deno/bin/deno
Browsers:
Chrome: 143.0.7499.171
Firefox: 146.0
Safari: 26.2
npmPackages:
@mastra/core: 1.0.0-beta.21 => 1.0.0-beta.21
@mastra/evals: 1.0.0-beta.4 => 1.0.0-beta.4
@mastra/libsql: 1.0.0-beta.11 => 1.0.0-beta.11
@mastra/loggers: 1.0.0-beta.4 => 1.0.0-beta.4
@mastra/memory: 1.0.0-beta.12 => 1.0.0-beta.12
@mastra/observability: 1.0.0-beta.10 => 1.0.0-beta.10
@types/node: ^25.0.3 => 25.0.3
mastra: 1.0.0-beta.13 => 1.0.0-beta.13
typescript: ^5.9.3 => 5.9.3
zod: ^4.3.5 => 4.3.5
npmGlobalPackages:
corepack: 0.34.0
netlify-cli: 23.9.5
npm: 11.6.0
secco: 3.1.2
Verification
- I have searched the existing issues to make sure this is not a duplicate
- I have included sufficient information for the team to reproduce and understand the issue