Use catalog: specifier for tslib in azure-sdk-for-js monorepo packages (#4570)

Generated `package.json` files for the azure-sdk-for-js monorepo were
pinning `tslib` to a hard-coded version (`^2.8.1`). The monorepo manages
shared tool/runtime versions through pnpm's catalog feature (see
`pnpm-workspace.yaml`), and other deps like `typescript`, `eslint`,
`rimraf`, etc. are already emitted as `catalog:`. `tslib` was the odd
one out, requiring a manual edit each regeneration to stay in sync with
the workspace catalog.

This switches the runtime dependency emitted by
`buildAzureMonorepoPackage` to `tslib: 'catalog:'` so it picks up
whatever the monorepo's catalog has pinned (`^2.8.1` today). Standalone
(non-monorepo) generators in `azurePackageCommon.ts` /
`packageCommon.ts` are intentionally left untouched, since `catalog:`
would not resolve outside the workspace.

Verified by running the `packageJson.test.ts` test-next suite (51/51
passing) and a `pnpm -r --filter '@azure-tools/typespec-ts...' build`.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: jeremymeng

.chronus/changes/use-tslib-catalog-monorepo-2026-6-5-10-39-0.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@azure-tools/typespec-ts"
+---
+
+Use the `catalog:` pnpm workspace specifier for the `tslib` dependency when generating `package.json` for the azure-sdk-for-js monorepo.

packages/typespec-ts/src/rlc-common/metadata/package-json/build-azure-monorepo-package.ts

@@ -43,7 +43,7 @@ export function getAzureMonorepoDependencies(config: AzureMonorepoInfoConfig) {
     "@azure/core-rest-pipeline": "^1.20.0",
     "@azure/core-util": "^1.12.0",
     "@azure/logger": "^1.2.0",
-    tslib: "^2.8.1",
+    tslib: "catalog:",
   };
 
   const testDeps = withTests