refactor(tsconfig): single root solution graph over host/client aggregates

Root tsconfig.json becomes a pure solution (files:[] + two references);
the former root host aggregate moves verbatim to tsconfig.host.json.
New tsconfig.base.client.json carries the shared client compiler shape
(jsx/DOM lib/types:[]), and tsconfig.client.json plus the 12
packages/client tsconfigs extend it instead of restating the trio.
tsconfig.build.json is deleted: the solution covers the full emit graph,
absorbing the command-goal typecheck/build drift.

Consumers migrate to the single graph: typecheck/build scripts and the
lefthook pre-push hook run bare `tsc -b` (pre-push now covers the client
side); the run-gates build gate needs typecheck so two concurrent tsc -b
runs cannot race the same tsbuildinfo; ts-project.ts and the standalone
doc-typecheck mode seed tsconfig.host.json explicitly (never the root
solution — flattening host+client into one program collides the cordis
Context merges); verify-cordis-config BFS seeds the root solution alone.

Per missions/tsconfig-single-graph-migration.md §2–§3.

scripts/doc-typecheck.ts

@@ -55,15 +55,20 @@ const configHost: ts.ParseConfigFileHost = {
   },
 }
 
-/** Load root settings and redirect workspace aliases to declarations from the coordinated build. */
+/**
+ * Load host-aggregate settings and redirect workspace aliases to declarations
+ * from the coordinated build. Doc fragments speak the host vocabulary; the host
+ * aggregate (never the root solution — it has no compilerOptions) carries the
+ * workspace paths via tsconfig.base.json.
+ */
 function builtTypeCompilerOptions(): ts.CompilerOptions {
-  const configPath = join(root, 'tsconfig.json')
+  const configPath = join(root, 'tsconfig.host.json')
   const parsed = ts.getParsedCommandLineOfConfigFile(configPath, {}, configHost)
   if (!parsed) throw new Error(`doc-typecheck: cannot parse ${configPath}`)
   if (parsed.errors.length > 0) {
     throw new Error(parsed.errors.map(error => ts.flattenDiagnosticMessageText(error.messageText, '\n')).join('\n'))
   }
-  if (parsed.options.paths === undefined) throw new Error('doc-typecheck: root tsconfig has no workspace paths')
+  if (parsed.options.paths === undefined) throw new Error('doc-typecheck: host tsconfig has no workspace paths')
   const paths = Object.fromEntries(Object.entries(parsed.options.paths).map(([specifier, candidates]) => [
     specifier,
     candidates.map(builtDeclarationPath),
@@ -125,9 +130,14 @@ function formatDiagnostics(diagnostics: readonly ts.Diagnostic[], blocks: Block[
   return remapBlockPaths(formatted, blocks)
 }
 
-/** Reuse the repo typecheck graph references from a temp project one directory below root. */
+/**
+ * Reuse the host-aggregate references from a temp project one directory below
+ * root. Doc fragments speak the host vocabulary, so the standalone project
+ * seeds tsconfig.host.json (never the root solution: flattening host+client
+ * into one program collides the cordis Context merges).
+ */
 function workspaceReferences(): { path: string }[] {
-  const file = join(root, 'tsconfig.json')
+  const file = join(root, 'tsconfig.host.json')
   // Parse with TypeScript's own JSONC reader: a regex comment stripper corrupts the `/*/` path
   // candidate in the workspace wildcard.
   const result = ts.readConfigFile(file, path => readFileSync(path, 'utf8'))
@@ -144,7 +154,7 @@ function workspaceReferences(): { path: string }[] {
 /** The standalone temp project used when no coordinated build owns declaration freshness. */
 function tempTsconfig(): string {
   return JSON.stringify({
-    extends: '../tsconfig.json',
+    extends: '../tsconfig.host.json',
     compilerOptions: {
       noUnusedLocals: false,
       noUnusedParameters: false,

scripts/gen-scoped-events.ts

@@ -370,7 +370,7 @@ function quote(value: string): string {
 
 /**
  * Render the generated scoped-event resolver module for one repository root.
- * @param projectRoot - repository root carrying tsconfig.json.
+ * @param projectRoot - repository root carrying tsconfig.host.json.
  * @returns complete generated TypeScript source.
  */
 export function renderScopedEvents(projectRoot: string = root): string {

scripts/run-gates.ts

@@ -228,7 +228,10 @@ function ciPrimaryGates(): Gate[] {
     ...docSyncLeafGates(),
     pnpmScript('module-graph', 'verify-module-graph', { label: 'module graph' }),
     pnpmScript('knip', 'knip'),
-    pnpmScript('build', 'build'),
+    // typecheck and build now drive the same root solution graph; without the
+    // dependency two concurrent `tsc -b` runs race the same tsbuildinfo files.
+    // The tsc step is an incremental no-op after typecheck.
+    pnpmScript('build', 'build', { needs: ['typecheck'] }),
     pnpmScript('publint', 'publint', { needs: ['build'] }),
     pnpmScript('node-next-types', 'verify-node-next-types', {
       label: 'node-next types',

scripts/ts-project.ts

@@ -22,9 +22,13 @@ const configHost: ts.ParseConfigFileHost = {
   },
 }
 
-/** Parse a root tsconfig and flatten all referenced projects into one semantic graph. */
+/**
+ * Parse the host aggregate tsconfig and flatten all referenced projects into one
+ * semantic graph. Never seed the root solution: flattening host+client into one
+ * program collides the cordis Context merges.
+ */
 function loadProjectGraph(projectRoot: string): ProjectGraph {
-  const rootConfigPath = resolve(projectRoot, 'tsconfig.json')
+  const rootConfigPath = resolve(projectRoot, 'tsconfig.host.json')
   const rootConfig = parseConfig(rootConfigPath)
   const rootNames = new Set<string>()
   const visited = new Set<string>()

scripts/verify-cordis-config.ts

@@ -152,12 +152,13 @@ function localPackageDirectories(): Map<string, string> {
 }
 
 function rootProjectReferences(): Set<string> {
-  // Typecheck runs two sibling aggregates (root = host program,
-  // tsconfig.client.json = client program; the two sides merge cordis Context
-  // under the same keys, so one program cannot see both). Seed both and follow
-  // any nested aggregate references to collect the covered leaf project set.
+  // The root solution references the host and client aggregates (the two
+  // sides merge cordis Context under the same keys, so one program cannot see
+  // both — but this BFS only collects reference paths, it never forms a
+  // program). Seed the solution and follow nested aggregate references to
+  // collect the covered leaf project set.
   const collected = new Set<string>()
-  const queue = [resolve(root, 'tsconfig.json'), resolve(root, 'tsconfig.client.json')]
+  const queue = [resolve(root, 'tsconfig.json')]
   const seen = new Set<string>()
   for (let file = queue.pop(); file !== undefined; file = queue.pop()) {
     if (seen.has(file)) continue