fix(tsconfig): stop four library tsconfigs from shadowing the workspace baseUrl

libs/cockpit-registry/tsconfig.json

@@ -2,8 +2,7 @@
   "extends": "../../tsconfig.base.json",
   "compilerOptions": {
     "composite": false,
-    "emitDeclarationOnly": false,
-    "baseUrl": "."
+    "emitDeclarationOnly": false
   },
   "files": [],
   "include": [],

libs/cockpit-runtime-bridge/tsconfig.json

@@ -2,8 +2,7 @@
   "extends": "../../tsconfig.base.json",
   "compilerOptions": {
     "composite": false,
-    "emitDeclarationOnly": false,
-    "baseUrl": "."
+    "emitDeclarationOnly": false
   },
   "files": [],
   "include": [],

libs/example-layouts/tsconfig.json

@@ -5,8 +5,7 @@
     "noPropertyAccessFromIndexSignature": true,
     "module": "preserve",
     "emitDeclarationOnly": false,
-    "composite": false,
-    "baseUrl": "."
+    "composite": false
   },
   "angularCompilerOptions": {
     "enableI18nLegacyMessageIdFormat": false,

libs/growth/tsconfig.json

@@ -1,7 +1,6 @@
 {
   "extends": "../../tsconfig.base.json",
   "compilerOptions": {
-    "baseUrl": ".",
     "composite": false,
     "emitDeclarationOnly": false
   },

scripts/tsconfig-path-inheritance.spec.mjs

@@ -0,0 +1,107 @@
+import { readFileSync, readdirSync, existsSync } from 'node:fs';
+import { dirname, join, relative, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+import ts from 'typescript';
+import { describe, expect, it } from 'vitest';
+
+// Guard for a latent module-resolution defect.
+//
+// `tsconfig.base.json` declares the workspace `paths` map with entries that are
+// relative to the workspace root (`libs/design-tokens/src/index.ts`). A project
+// tsconfig that extends the base and re-declares `"baseUrl": "."` overrides the
+// inherited base directory, because `baseUrl` outranks the implicit
+// `pathsBasePath`. Every inherited substitution is then probed under the
+// *library* folder (`libs/<lib>/libs/design-tokens/src/index.ts`), misses, and
+// only resolves because the npm workspace symlink in `node_modules` happens to
+// land on the same source file. Builds stay green, so nothing catches it.
+//
+// A project that declares its own `paths` (including an empty `{}`) is exempt:
+// there `baseUrl` does real directory-resolution work and shadows nothing.
+
+const workspaceRoot = dirname(dirname(fileURLToPath(import.meta.url)));
+const baseConfigPath = join(workspaceRoot, 'tsconfig.base.json');
+
+function readConfig(configPath) {
+  const parsed = ts.parseConfigFileTextToJson(configPath, readFileSync(configPath, 'utf8'));
+  expect(parsed.error, `failed to parse ${relative(workspaceRoot, configPath)}`).toBeUndefined();
+  return parsed.config ?? {};
+}
+
+/**
+ * Walk the `extends` chain from `configPath` upwards, stopping at (and
+ * excluding) `tsconfig.base.json`. Returns null when the chain never reaches
+ * the base config — such a project does not inherit the workspace `paths`.
+ */
+function chainBelowBase(configPath) {
+  const chain = [];
+  let current = configPath;
+  for (let hop = 0; hop < 10; hop += 1) {
+    if (current === baseConfigPath) return chain;
+    const config = readConfig(current);
+    chain.push({ path: current, config });
+    if (typeof config.extends !== 'string') return null;
+    const next = resolve(dirname(current), config.extends);
+    current = existsSync(next) ? next : `${next}.json`;
+    if (!existsSync(current)) return null;
+  }
+  return null;
+}
+
+function libraryTsconfigs() {
+  const found = [];
+  for (const entry of readdirSync(join(workspaceRoot, 'libs'), { withFileTypes: true })) {
+    if (!entry.isDirectory()) continue;
+    const libDir = join(workspaceRoot, 'libs', entry.name);
+    for (const file of readdirSync(libDir)) {
+      if (file.startsWith('tsconfig') && file.endsWith('.json')) found.push(join(libDir, file));
+    }
+  }
+  return found.sort();
+}
+
+describe('library tsconfig path inheritance', () => {
+  it('never shadows the workspace baseUrl the inherited paths map resolves against', () => {
+    const offenders = [];
+    for (const configPath of libraryTsconfigs()) {
+      const chain = chainBelowBase(configPath);
+      if (chain === null) continue;
+      const declaresOwnPaths = chain.some((link) => link.config.compilerOptions?.paths !== undefined);
+      if (declaresOwnPaths) continue;
+      const shadowing = chain.find((link) => link.config.compilerOptions?.baseUrl !== undefined);
+      if (shadowing) offenders.push(relative(workspaceRoot, shadowing.path));
+    }
+    expect([...new Set(offenders)]).toEqual([]);
+  });
+
+  it.each([
+    'libs/cockpit-runtime-bridge',
+    'libs/growth',
+    'libs/example-layouts',
+    'libs/cockpit-registry',
+  ])('resolves @threadplane/design-tokens through the paths map from %s', (libDir) => {
+    const configPath = join(workspaceRoot, libDir, 'tsconfig.json');
+    const parsed = ts.getParsedCommandLineOfConfigFile(configPath, {}, {
+      ...ts.sys,
+      onUnRecoverableConfigFileDiagnostic: (diagnostic) => {
+        throw new Error(ts.flattenDiagnosticMessageText(diagnostic.messageText, '\n'));
+      },
+      getCurrentDirectory: () => workspaceRoot,
+      useCaseSensitiveFileNames: true,
+    });
+    expect(parsed, `could not parse ${libDir}/tsconfig.json`).toBeDefined();
+
+    const containingFile = join(workspaceRoot, libDir, 'src', 'index.ts');
+    const resolved = ts.resolveModuleName(
+      '@threadplane/design-tokens',
+      containingFile,
+      parsed.options,
+      ts.sys,
+    ).resolvedModule;
+
+    expect(resolved?.resolvedFileName).toBe(join(workspaceRoot, 'libs/design-tokens/src/index.ts'));
+    // A `packageId` means TypeScript fell through the `paths` substitution and
+    // found the source only via the npm workspace symlink under node_modules.
+    expect(resolved?.packageId, 'resolved via node_modules symlink, not the paths map').toBeUndefined();
+  });
+});