fix(libs): pin the type-tests compiler; document the tsconfig baseUrl blocker

[blove]

What changed

Two things, both downstream of trying to remove baseUrl from tsconfig.base.json.

1. The type-tests targets now run the workspace TypeScript.

They invoked npx tsc, which does not resolve to the workspace compiler here. @dawn-ai/core depends on @typescript/typescript6, which depends on @typescript/old (npm:typescript@6.0.2); that package's tsc bin wins the hoist at node_modules/.bin/tsc. So npx tsc is TypeScript 6.0.2 while every other target compiles with the declared 5.9.3:

$ npx tsc --version
Version 6.0.2
$ node -e "console.log(require('typescript/package.json').version)"
5.9.3

That mismatch is what raised TS5101 on the inherited baseUrl, which #1064 silenced with "ignoreDeprecations": "6.0". The targets now invoke node ./node_modules/typescript/bin/tsc, so they type-check the public API with the compiler the workspace actually declares, and the ignoreDeprecations holding action is gone from all three configs.

The "rootDir": "../.." lines stay — they solve the unrelated problem of type-specs importing sibling libraries through path mappings.

2. baseUrl stays in tsconfig.base.json, with the reason recorded next to it.

Why baseUrl could not be removed

The premise checks out: since TypeScript 5.0 the paths entries resolve against the directory of the tsconfig that declares them, and --traceResolution confirms it against the installed compilers — with baseUrl gone, @threadplane/chat still resolves to libs/chat/src/public-api.ts, now via pathsBasePath rather than baseUrl. No source file relies on baseUrl for bare-specifier resolution either (there are no from 'libs/…'-style imports anywhere in the repo).

What breaks is Nx. @nx/angular:package and @nx/js:tsc call createTmpTsConfig, which writes a generated tsconfig to tmp/<projectRoot>/build/ that re-declares the whole paths map with dependency entries remapped to their dist outputs:

"@threadplane/telemetry/browser": [
  "dist/libs/telemetry/browser",
  "./dist/libs/telemetry/src/browser/public-api",
  "./dist/libs/telemetry/src/browser/public-api.ts"
]

The first entry comes from dep.outputs and is workspace-root-relative, i.e. non-relative. With no baseUrl anywhere in the chain, TypeScript raises TS5090 and discards the entire paths map, and the generated config's directory is the wrong base for the remaining entries regardless. Every library with a workspace library dependency then fails:

error TS5090: Non-relative paths are not allowed when 'baseUrl' is not set.
libs/render/src/lib/render-element.component.ts:24:73 - error TS2307:
  Cannot find module '@threadplane/telemetry/browser'
libs/cockpit-shell/src/lib/workspace-presentation.ts:9:8 - error TS2307:
  Cannot find module '@threadplane/cockpit-registry'

render:build:production (ng-packagr) and cockpit-shell:build (@nx/js:tsc) both fail this way; chat, ag-ui and langgraph builds are then skipped as dependents. createTmpTsConfig does take a useWorkspaceAsBaseUrl flag that would fix it, but the executors call it with the default false and it is not reachable from project.json. Prefixing the base paths values with ./ does not help — Nx's own injected dist/… entry is still non-relative.

So this needs an Nx-side fix (or migrating to the Nx TS-solution setup, which drops paths for project references) before baseUrl can go. The comment in tsconfig.base.json records that so the next attempt starts there.

Other baseUrl declarations, and why they are left alone

• libs/{cockpit-runtime-bridge,growth,example-layouts,cockpit-registry}/tsconfig.json set "baseUrl": "." (the library directory). Because baseUrl outranks pathsBasePath, these already redirect the inherited base paths into the library folder — @threadplane/design-tokens in example-layouts tries libs/example-layouts/libs/design-tokens/src/index.ts, misses, and only resolves because the npm workspace symlink under node_modules happens to point at the same source. That is a pre-existing latent bug, unchanged by this PR, and removing those lines changes resolution for those builds — worth its own change rather than riding along here.
• libs/growth-capture, apps/growth-research pair "baseUrl": "." with "paths": {}, so baseUrl is doing real directory-resolution work for those NodeNext projects. Not redundant.
• apps/website declares its own complete paths (including the Next.js @/* convention) alongside baseUrl. Self-contained and a separate decision.
• The cockpit/**/{python,angular/e2e} and examples/**/e2e configs either declare baseUrl plus their own paths together, or do not extend tsconfig.base.json at all. Unaffected by this change.

Verification

• npx nx run-many -t lint,test,build --projects=chat,ag-ui,langgraph,render,a2ui,telemetry,middleware,cockpit-registry,cockpit-shell,scripts --skip-nx-cache — green (0 lint errors; warnings only)
• chat:type-tests, ag-ui:type-tests, langgraph:type-tests — all green on TypeScript 5.9.3 with no ignoreDeprecations
• Mutation-checked the pinned compiler: appending const x: number = "s" to libs/ag-ui/src/lib/provide-agent.type-spec.ts fails the target with TS2322, so it is not passing vacuously
• npx vitest run --root apps/website --reporter=dot — 138 files, 1394 tests passed
• GROWTH_FORM_POLICY=growth_v1 npx nx build website — green
• npx nx run-many -t build --projects=examples-chat-angular,cockpit-render-repeat-loops-angular,cockpit-chat-debug-angular — green
• npx nx run e2e-harness:lint (the one other bare-tsc target) — green; its tsconfig is standalone and declares no baseUrl
• npx tsc --noEmit -p tsconfig.base.json is not meaningful here: the file has no include/files, so it would sweep every .ts in the workspace. The equivalent editor-facing surfaces are covered by the website build (Next.js) and the library builds.

🤖 Generated with Claude Code

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