diff --git a/.gitignore b/.gitignore
index 790c3cc26..7567f3269 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@ node_modules/
 !tests/fixtures/npm/node_modules/
 !tests/corpus/*/node_modules/
 !tests/fixtures/npm-static/node_modules/
+!tests/fixtures/npm-static/nested/inner/node_modules/
 !tests/fixtures/npm/store/*/node_modules/
 !tests/fixtures/npm/cases/*/node_modules/
 !tests/fixtures/provenance/node_modules/
diff --git a/packages/compiler/src/frontend/lowering/lower-modules.ts b/packages/compiler/src/frontend/lowering/lower-modules.ts
index 6c73a2816..6d34fd88a 100644
--- a/packages/compiler/src/frontend/lowering/lower-modules.ts
+++ b/packages/compiler/src/frontend/lowering/lower-modules.ts
@@ -7,7 +7,7 @@ import type { Lowerer } from "./lowerer.js";
 import { dirname as dirnamePath, resolve as resolvePath } from "node:path";
 import { NpmGraphBuilder, packageNameOfPath, probeNodeImportRefusal } from "../npm.js";
 import { isNpmStaticPackage } from "../npm-static.js";
-import { isJsSourceFileName } from "../shared.js";
+import { isJsSourceFileName, isRelativeSpecifier } from "../shared.js";
 import { cjsExportAssignmentOf, cjsExportDiscardReason, isCjsJsFile, isJsSourceFile, isRequireStatement, locOf, orderedImportsOf, resolveImport, resolveNpmImport } from "../program.js";
 import { invalidJsonModuleDiag, npmEmbedFailedDiag, requiresDynamicImportDiag, unsupportedDiag } from "../../diagnostics/diagnostic.js";
 import { BOOL, DYN, IrClassDef, IrExpr, IrFunction, IrGlobal, IrRecordShape, IrStmt, IrUnionDef, JSVAL, RUNTIME_ERROR_CLASSES, STRING, SrcLoc, VOID, canConvertToDyn, isUnitType } from "../../ir/nodes.js";
@@ -75,7 +75,7 @@ export interface FileParts {
     sf: ts.SourceFile,
     spec: string,
   ): ts.SourceFile | null {
-    if (!spec.startsWith("./") && !spec.startsWith("../") && !spec.startsWith("/")) return null;
+    if (!isRelativeSpecifier(spec) && !spec.startsWith("/")) return null;
     const dep = resolveImport(program, sf, spec);
     if (!dep || dep.isDeclarationFile) return null;
     if (dep.fileName.endsWith(".json") || dep.fileName.endsWith(".cts")) return null;
@@ -240,7 +240,7 @@ export interface FileParts {
         // and node_modules files never lower as program modules — the
         // import silently dropped).
         const relPkg =
-          npm === null && (spec.startsWith("./") || spec.startsWith("../"))
+          npm === null && isRelativeSpecifier(spec)
             ? packageNameOfPath(resolvePath(dirnamePath(fp.sf.fileName), spec))
             : null;
         const relIsJs =
diff --git a/packages/compiler/src/frontend/lowering/lower-stmts.ts b/packages/compiler/src/frontend/lowering/lower-stmts.ts
index 49953fbc9..459498921 100644
--- a/packages/compiler/src/frontend/lowering/lower-stmts.ts
+++ b/packages/compiler/src/frontend/lowering/lower-stmts.ts
@@ -24,7 +24,7 @@ import { lowerEnumDeclaration } from "./lower-enums.js";
 import { abstractPropertyDeclOf, aliasTypeofNarrows, probeLower, pureReemittable, symbolFieldInfo } from "./lower-exprs.js";
 import { UNSUPPORTED, checkerPanicDiag, isCheckerPanic, requiresDynamicDiag } from "../../diagnostics/diagnostic.js";
 import { isUnitOnlyTsType, unitOnlyUnion } from "../types.js";
-import { canonicalBuiltinModule } from "../shared.js";
+import { canonicalBuiltinModule, isRelativeSpecifier } from "../shared.js";
 import { probeNodeRequireRefusal } from "../npm.js";
 
 /** `const X = /* @__PURE__ *\/ makeX()` at a module's top level: every
@@ -3017,7 +3017,7 @@ export function lowerVarDecl(L: Lowerer, decl: ts.VariableDeclaration, isLet: bo
       if (isCjsJsFile(sf)) {
         const spec = requireSpecOf(expr)!;
         if (
-          !spec.startsWith("./") && !spec.startsWith("../") &&
+          !isRelativeSpecifier(spec) &&
           canonicalBuiltinModule(spec) === null
         ) {
           const refusal = probeNodeRequireRefusal(sf.fileName, spec);
diff --git a/packages/compiler/src/frontend/lowering/lowerer.ts b/packages/compiler/src/frontend/lowering/lowerer.ts
index e6c7b90b8..9bb1f0e66 100644
--- a/packages/compiler/src/frontend/lowering/lowerer.ts
+++ b/packages/compiler/src/frontend/lowering/lowerer.ts
@@ -12,6 +12,7 @@
  * - Lexical scoping is resolved here: locals get function-unique ids
  *   ("x.0", "x.1" for shadowing); the IR is scope-flat.
  */
+import { isRelativeSpecifier } from "../shared.js";
 import * as ts from "../ts7/adapter.js";
 import type { ScrDiagnostic } from "../../diagnostics/diagnostic.js";
 import {
@@ -1236,7 +1237,7 @@ export class Lowerer {
       return null;
     }
     const spec = importDecl.moduleSpecifier.text;
-    if (!spec.startsWith("./") && !spec.startsWith("../")) return null;
+    if (!isRelativeSpecifier(spec)) return null;
     const dep = resolveImport(this.program, importDecl.getSourceFile(), spec);
     if (!dep || !isJsSourceFile(dep) || isNodeEsmFile(dep)) return null;
     return dep;
@@ -1263,7 +1264,7 @@ export class Lowerer {
         return false;
       }
       const spec = requireSpecOf(decl.initializer);
-      if (spec === null || !(spec.startsWith("./") || spec.startsWith("../"))) return false;
+      if (spec === null || !isRelativeSpecifier(spec)) return false;
     }
     // SINGLE-VALUE exporters (`module.exports = Countdown` / `= double` /
     // `= 42`): the requirer's binding IS the exported value, not a
@@ -1364,7 +1365,7 @@ export class Lowerer {
    * specifier is not a relative program module (builtins load nothing;
    * anything else kept its preflight fence). */
   requireInitStmt(spec: string, node: ts.Node): IrStmt | null {
-    if (!spec.startsWith("./") && !spec.startsWith("../")) return null;
+    if (!isRelativeSpecifier(spec)) return null;
     const dep = resolveImport(this.program, node.getSourceFile(), spec);
     if (!dep || dep.fileName.endsWith(".json")) return null;
     const initName = this.initNameOf.get(dep);
diff --git a/packages/compiler/src/frontend/program.ts b/packages/compiler/src/frontend/program.ts
index d6612a074..0e0d22ed2 100644
--- a/packages/compiler/src/frontend/program.ts
+++ b/packages/compiler/src/frontend/program.ts
@@ -63,11 +63,13 @@ import {
   fallbackDtsPath,
   isJsSourceFileName,
   isNodeTypesPath,
+  isRelativeSpecifier,
   JS_ANY_OPERATOR_CODES,
   JS_RELAXED_TSC_CODES,
   overridesDtsPath,
   registerWorkspacePackage,
   SUPPORTED_NODE_MODULES,
+  workspacePackageOfPath,
 } from "./shared.js";
 
 const BASE_OPTIONS: ts.Ts7CompilerOptions = {
@@ -883,11 +885,17 @@ function nonInertTopLevel7(program: ts.Program, sf: ts.SourceFile): ts.Node | nu
     if (ts.isCallExpression(e) || ts.isNewExpression(e)) {
       if (!dtsRooted(e.expression) || !ts.isIdentifier(chainRoot7(e.expression))) return false;
       const args = e.arguments ?? [];
+      // A CALLABLE argument is admissible when it is itself dts-rooted:
+      // a builtin-owned function value (vercel's `promisify(fs.readFile)`
+      // at every cycle member's top level) is runtime-implemented — even
+      // if the builtin callee invokes it, no user code runs and no
+      // cluster binding is observable. Function literals and user
+      // callables keep the refusal.
       return args.every(
         (a) =>
           inert(a) &&
           !containsFunctionLike(a) &&
-          checker.getCallSignatures(checker.getTypeAtLocation(a)).length === 0,
+          (checker.getCallSignatures(checker.getTypeAtLocation(a)).length === 0 || dtsRooted(a)),
       );
     }
     return false;
@@ -1006,7 +1014,7 @@ function resolveNpmImport7(
   fromFileName: string,
   specifier: string,
 ): { packageName: string; version?: string; typesFile: string } | null {
-  if (specifier.startsWith("./") || specifier.startsWith("../") || specifier.startsWith("node:")) {
+  if (isRelativeSpecifier(specifier) || specifier.startsWith("node:")) {
     return null;
   }
   // --provenance-sources: a registered specifier is NOT an npm import —
@@ -1106,6 +1114,61 @@ function preflight7(load: LoadResult): {
   const { program, entry } = load;
   const diags: ScrDiagnostic[] = [...load.configDiags];
 
+  // Workspace-linked packages register BEFORE the tsc gate. Their files
+  // live at realpaths OUTSIDE node_modules (the monorepo-tool symlink
+  // shape), so nothing path-shaped marks them as npm surface — yet their
+  // shipped JS is the identical foreign-tsconfig story as node_modules JS
+  // (the island executes it under --dynamic; the author's own build
+  // checked it, the program's author cannot fix it). The lazy
+  // registration inside the import-fence walk below runs AFTER errorsOf,
+  // too late for the gate, so one pass over the program's import edges
+  // registers them up front: every bare specifier any program file loads —
+  // import/export declarations, dynamic import("literal") (tsgo chases
+  // those into the program too; vercel's CLI reaches @vercel/go exactly
+  // that way), require("literal") — resolved with the own resolver,
+  // workspace answers recorded.
+  {
+    const supportedBuiltins = new Set<string>(SUPPORTED_NODE_MODULES);
+    const probed = new Set<string>();
+    const probe = (fromFile: string, spec: string): void => {
+      if (
+        isRelativeSpecifier(spec) ||
+        spec.startsWith("#") ||
+        spec.startsWith("node:") ||
+        supportedBuiltins.has(spec)
+      ) {
+        return;
+      }
+      const key = `${dirname(fromFile)} ${spec}`;
+      if (probed.has(key)) return;
+      probed.add(key);
+      const r = resolveBareModule(fromFile, spec);
+      if (r !== null && r.workspaceDir !== undefined) registerWorkspacePackage(r.packageName, r.workspaceDir);
+    };
+    for (const sf of program.getSourceFiles()) {
+      if (sf.isDeclarationFile || sf.fileName.endsWith(".json")) continue;
+      ts.walkPreorder(sf, (n) => {
+        if (
+          (ts.isImportDeclaration(n) || ts.isExportDeclaration(n)) &&
+          n.moduleSpecifier !== undefined &&
+          ts.isStringLiteral(n.moduleSpecifier)
+        ) {
+          probe(sf.fileName, n.moduleSpecifier.text);
+          return "skip";
+        }
+        if (ts.isCallExpression(n)) {
+          const arg = n.arguments[0];
+          const isImportCall = n.expression.kind === ts.SyntaxKind.ImportKeyword;
+          const isRequireCall = ts.isIdentifier(n.expression) && n.expression.text === "require";
+          if ((isImportCall || isRequireCall) && arg !== undefined && ts.isStringLiteralLike(arg)) {
+            probe(sf.fileName, arg.text);
+          }
+        }
+        return undefined;
+      });
+    }
+  }
+
   const toPassthrough = (d: ts.Diagnostic): ScrDiagnostic => {
     const message = ts.flattenDiagnosticMessageText(d, "\n");
     // File-less (global/options) diagnostics anchor at the entry with a
@@ -1167,8 +1230,20 @@ function preflight7(load: LoadResult): {
    * every flagless compile (depth 0 keeps node_modules JS out of the
    * program), and the packages themselves still island — so their checker
    * errors never gate a build. */
+  /* WORKSPACE-LINKED shipped JS is the same story at a different path: the
+   * package's files realpath OUTSIDE node_modules (so depth-0 exclusion
+   * never saw them and allowJs+checkJs pulls them straight into the
+   * program), but they are npm surface all the same — the island executes
+   * them, the program's author cannot fix them (vercel's @vercel/go ships
+   * an ncc bundle with dozens of checker errors). Registered up front (the
+   * pass above), suppressed here unless --npm-static opted them into being
+   * program modules. */
+  const islandJsFile = (file: string): boolean =>
+    isJsSourceFileName(file) &&
+    npmStaticPackageOfPath(file) === null &&
+    (isNodeModulesPath(file) || workspacePackageOfPath(file) !== null);
   const nodeModulesJsSuppressed = (d: ts.Diagnostic): boolean =>
-    d.fileName !== undefined && isNodeModulesPath(d.fileName) && isJsSourceFileName(d.fileName);
+    d.fileName !== undefined && islandJsFile(d.fileName);
   /* JSDoc TYPE positions in JS files are documentation Node never reads:
    * a name-resolution failure THERE (2304/2552 — prettier's utilities.js
    * spells a mapped type over a @template name it never declared) types
@@ -1246,7 +1321,13 @@ function preflight7(load: LoadResult): {
         sf.fileName !== ambient &&
         !sf.isDeclarationFile &&
         !sf.fileName.endsWith(".json") &&
-        (!isNodeModulesPath(sf.fileName) || npmStaticPackageOfPath(sf.fileName) !== null),
+        (!isNodeModulesPath(sf.fileName) || npmStaticPackageOfPath(sf.fileName) !== null) &&
+        // Workspace-linked shipped JS (see islandJsFile): its execution
+        // home is the island exactly like node_modules JS, so no import
+        // fences, no module edges, no statement counts from it. Its .ts
+        // files (a workspace package imported bare AND reached relatively)
+        // stay program source — only the island-bound JS steps out.
+        !islandJsFile(sf.fileName),
     );
 
   const ambientModules = new Set<string>(SUPPORTED_NODE_MODULES);
@@ -1339,7 +1420,7 @@ function preflight7(load: LoadResult): {
         if (stmt.isTypeOnly || erasedTypeOnlyReexport(stmt)) continue;
         if (!stmt.moduleSpecifier) continue;
         const fromSpec = ts.isStringLiteral(stmt.moduleSpecifier) ? stmt.moduleSpecifier.text : "";
-        if (!fromSpec.startsWith("./") && !fromSpec.startsWith("../")) {
+        if (!isRelativeSpecifier(fromSpec)) {
           // NAMED re-exports from a SUPPORTED builtin pass (`export { ok }
           // from "node:assert"` — prettier's universal/assert facade): the
           // statement binds nothing locally and evaluates nothing (builtins
@@ -1389,7 +1470,7 @@ function preflight7(load: LoadResult): {
       const specNode: ts.Expression | undefined = stmt.moduleSpecifier;
       if (specNode === undefined || !ts.isStringLiteral(specNode)) continue;
       const spec = specNode.text;
-      const isRelative = spec.startsWith("./") || spec.startsWith("../");
+      const isRelative = isRelativeSpecifier(spec);
       const isBare = !isRelative && !ambientModules.has(spec);
       // An import edge Node's own resolution refuses BEFORE any module
       // evaluates: recorded as a startup-crash candidate (the Node-order
@@ -1524,17 +1605,27 @@ function preflight7(load: LoadResult): {
         selfImportTdzFences7(program, sf, clause, diags);
       }
       if (clause) {
-        // Default imports of SUPPORTED builtins in JS sources pass: Node's
-        // default export of a CJS builtin IS the module object, so the
-        // binding exposes exactly the namespace-import surface and the
-        // lowering keys the same tables (builtinNamespaceModuleOf's
-        // default-import twin). TS sources keep the fence — the checker
-        // itself refuses the spelling without interop flags, and the
-        // SC1012 wording beats the raw TS1259. The callable module
-        // objects (assert, events, test) stay allowed everywhere.
+        // Default imports of SUPPORTED builtins pass where the spelling is
+        // legal: Node's default export of a CJS builtin IS the module
+        // object, so the binding exposes exactly the namespace-import
+        // surface and the lowering keys the same tables
+        // (builtinNamespaceModuleOf's default-import twin). JS sources
+        // always (Node never asks for interop flags); TS sources when the
+        // adopted interop knobs made the checker accept the spelling
+        // (vercel's `import os from 'os'` under esModuleInterop — the
+        // program TYPECHECKED, so the form is the project's own legal
+        // dialect). A TS project without interop flags keeps the fence:
+        // the SC1012 wording beats the raw TS1259 at the same site. The
+        // callable module objects (assert, events, test) stay allowed
+        // everywhere.
+        const opts = program.getCompilerOptions() as {
+          esModuleInterop?: boolean;
+          allowSyntheticDefaultImports?: boolean;
+        };
+        const interopOn = opts.esModuleInterop === true || opts.allowSyntheticDefaultImports === true;
         const defaultOk =
           builtinDefaultImportModule(spec) !== null ||
-          (isJsSourceFileName(sf.fileName) && canonicalBuiltinModule(spec) !== null);
+          ((isJsSourceFileName(sf.fileName) || interopOn) && canonicalBuiltinModule(spec) !== null);
         if (clause.name && !isJson && dep === null && !defaultOk) {
           diags.push(unsupportedDiag("SC1012", locOf7(clause.name)));
         }
@@ -1627,7 +1718,7 @@ function preflight7(load: LoadResult): {
               continue;
             }
           }
-          const isRelative = req.spec.startsWith("./") || req.spec.startsWith("../");
+          const isRelative = isRelativeSpecifier(req.spec);
           if (!isRelative) {
             if (
               canonicalBuiltinModule(req.spec) === null &&
@@ -1671,7 +1762,7 @@ function preflight7(load: LoadResult): {
         for (const call of nestedBareRequiresOf7(sf)) {
           const spec = requireSpecOf7(call)!;
           const loc = { file: sf.fileName, start: call.getStart(sf), end: call.getEnd() };
-          if (!spec.startsWith("./") && !spec.startsWith("../")) {
+          if (!isRelativeSpecifier(spec)) {
             if (canonicalBuiltinModule(spec) === null && !processModuleAliasRequire7(spec, null)) {
               // Binding-less by construction — same require-site throw
               // channel as the statement-level form above.
@@ -1914,7 +2005,7 @@ function cjsNamedImportLinkCheck(
   diags: ScrDiagnostic[],
 ): StartupCrash | null {
   const lexMemo = new Map<ts.SourceFile, Set<string>>();
-  const isRelative = (spec: string): boolean => spec.startsWith("./") || spec.startsWith("../");
+  const isRelative = isRelativeSpecifier;
   // Relative specifiers resolve as ever; PROJECT imports (#alias/self-name
   // — the same package.json-mediated edges preflight admits) join them so
   // a named import THROUGH one of a CommonJS module keeps Node's lexer
@@ -2168,7 +2259,7 @@ export function orderedImportsOf(
     if (ts.isImportDeclaration(stmt) && erasedTypeOnlyImport(stmt)) continue;
     if (!stmt.moduleSpecifier || !ts.isStringLiteral(stmt.moduleSpecifier)) continue;
     const spec = stmt.moduleSpecifier.text;
-    const isRelative = spec.startsWith("./") || spec.startsWith("../");
+    const isRelative = isRelativeSpecifier(spec);
     // Relative edges as ever; PROJECT imports (#alias/self-name — the
     // package.json-mediated specifiers preflight admits as user-module
     // edges) resolve to the same dep so the importer's %init header calls
@@ -2190,7 +2281,7 @@ export function orderedImportsOf(
  * already classified the import; this is the lookup the module-order and
  * lowering paths share. */
 function npmStaticDepSf7(program: ts.Program, sf: ts.SourceFile, spec: string): ts.SourceFile | null {
-  if (!npmStaticActive() || spec.startsWith("./") || spec.startsWith("../")) return null;
+  if (!npmStaticActive() || isRelativeSpecifier(spec)) return null;
   if (spec.startsWith("node:") || spec.startsWith("#")) return null;
   const npm = resolveNpmImport7(sf.fileName, spec);
   if (npm === null || !isNpmStaticPackage(npm.packageName)) return null;
diff --git a/packages/compiler/src/frontend/shared.ts b/packages/compiler/src/frontend/shared.ts
index 3342e42cb..c6b86e7d2 100644
--- a/packages/compiler/src/frontend/shared.ts
+++ b/packages/compiler/src/frontend/shared.ts
@@ -118,6 +118,16 @@ export function workspacePackageOfPath(path: string): string | null {
   return null;
 }
 
+/** Node's relative-specifier family: './x', '../x', and the bare '.' /
+ * '..' directory forms (path resolution treats them identically —
+ * vercel's CLI imports `from '..'` for a parent directory's index).
+ * Anything else is a package, builtin, or package.json-mediated
+ * specifier. ('...' and friends are legal PACKAGE names — only the exact
+ * dot forms are relative.) */
+export function isRelativeSpecifier(spec: string): boolean {
+  return spec === "." || spec === ".." || spec.startsWith("./") || spec.startsWith("../");
+}
+
 /** Package name from a path under node_modules — the LAST node_modules
  * segment (nested installs blame the innermost package), scoped-aware:
  * ".../node_modules/@scope/pkg/dist/x.d.ts" → "@scope/pkg". Paths with no
diff --git a/packages/compiler/src/index.ts b/packages/compiler/src/index.ts
index 4393cc01f..9184b7581 100644
--- a/packages/compiler/src/index.ts
+++ b/packages/compiler/src/index.ts
@@ -11,7 +11,7 @@ import { checkPreflight, isNodeTypesPath, loadProgram, resolveNpmImport, type Lo
 import { npmStaticIneligibleReason, npmStaticOffenders, npmStaticPackageOfPath } from "./frontend/npm-static.js";
 import { provenanceSources } from "./frontend/provenance-registry.js";
 import { resolveBareModule } from "./frontend/resolve.js";
-import { isJsSourceFileName } from "./frontend/shared.js";
+import { isJsSourceFileName, isRelativeSpecifier } from "./frontend/shared.js";
 import { lowerToIr, type LowerOptions, type LowerResult } from "./frontend/lowering/lowerer.js";
 import type { CoverageInput, NpmStaticStatus } from "./coverage/report.js";
 
@@ -147,21 +147,26 @@ interface Frontend {
  * Rejected candidates report their reason so the coverage output says why
  * auto skipped them. */
 function detectAutoPackages(load: LoadResult, statuses: NpmStaticStatus[]): string[] {
-  const seen = new Map<string, string>(); // package → typesFile
+  // package → the resolved types file AND the file whose import found it:
+  // the runtime-JS probe below must resolve from the SAME importing file,
+  // or a package visible only to a nested package.json realm (a pnpm
+  // monorepo's packages/*/node_modules, unreachable from the entry's own
+  // walk-up) answers "no runtime JS" for perfectly ordinary installs.
+  const seen = new Map<string, { typesFile: string; fromFile: string }>();
   for (const sf of [...load.moduleOrder, load.entry]) {
     if (sf.fileName.includes("/node_modules/")) continue;
     for (const stmt of sf.statements) {
       if (!ts7IsImportWithStringSpec(stmt)) continue;
       const spec = (stmt as { moduleSpecifier: { text: string } }).moduleSpecifier.text;
-      if (spec.startsWith("./") || spec.startsWith("../") || spec.startsWith("node:") || spec.startsWith("#")) continue;
+      if (isRelativeSpecifier(spec) || spec.startsWith("node:") || spec.startsWith("#")) continue;
       const npm = resolveNpmImport(sf.fileName, spec);
       if (npm === null || isNodeTypesPath(npm.typesFile)) continue;
-      if (!seen.has(npm.packageName)) seen.set(npm.packageName, npm.typesFile);
+      if (!seen.has(npm.packageName)) seen.set(npm.packageName, { typesFile: npm.typesFile, fromFile: sf.fileName });
     }
   }
   const chosen: string[] = [];
-  for (const [pkg, typesFile] of seen) {
-    const jsEntry = resolveBareModule(load.entry.fileName, pkg, "js-only");
+  for (const [pkg, { typesFile, fromFile }] of seen) {
+    const jsEntry = resolveBareModule(fromFile, pkg, "js-only");
     const reason = npmStaticIneligibleReason(
       pkg,
       typesFile,
diff --git a/packages/compiler/test/ts7/baselines/order-parity.json b/packages/compiler/test/ts7/baselines/order-parity.json
index f495a5126..c37c8049d 100644
--- a/packages/compiler/test/ts7/baselines/order-parity.json
+++ b/packages/compiler/test/ts7/baselines/order-parity.json
@@ -4010,6 +4010,21 @@
    ],
    "diags": []
   },
+  "<repo>/tests/corpus/2390-dot-requires/main.cjs": {
+   "order": [
+    "<repo>/tests/corpus/2390-dot-requires/shared.cjs",
+    "<repo>/tests/corpus/2390-dot-requires/sub/index.cjs",
+    "<repo>/tests/corpus/2390-dot-requires/sub/child.cjs",
+    "<repo>/tests/corpus/2390-dot-requires/main.cjs"
+   ],
+   "diags": []
+  },
+  "<repo>/tests/corpus/2391-default-builtin-imports/main.ts": {
+   "order": [
+    "<repo>/tests/corpus/2391-default-builtin-imports/main.ts"
+   ],
+   "diags": []
+  },
   "<repo>/tests/corpus/240-stdout-write.ts": {
    "order": [
     "<repo>/tests/corpus/240-stdout-write.ts"
@@ -5829,6 +5844,48 @@
    ],
    "diags": []
   },
+  "<repo>/tests/fixtures/node-types/argv-env.ts": {
+   "order": [
+    "<repo>/tests/fixtures/node-types/argv-env.ts"
+   ],
+   "diags": []
+  },
+  "<repo>/tests/fixtures/node-types/fenced.ts": {
+   "order": [
+    "<repo>/tests/fixtures/node-types/fenced.ts"
+   ],
+   "diags": []
+  },
+  "<repo>/tests/fixtures/node-types/import-fences.ts": {
+   "order": [
+    "<repo>/tests/fixtures/node-types/import-fences.ts"
+   ],
+   "diags": [
+    {
+     "code": "SC1010",
+     "message": "the 'v8' module is not supported yet",
+     "loc": {
+      "file": "<repo>/tests/fixtures/node-types/import-fences.ts",
+      "start": 422,
+      "end": 461
+     },
+     "milestone": "M4",
+     "hint": "relative imports (./file, ../dir/file), package.json-mediated project imports (#alias via the imports field, self-name references via exports), installed npm packages (their code runs under --dynamic), and the built-in fs, fs/promises, path, os, url, crypto, zlib, child_process, net, http, tls, https, http2, dgram, dns, util, util/types, string_decoder, readline, events, stream, buffer, assert, assert/strict, worker_threads, cluster, tty, async_hooks, timers, timers/promises, diagnostics_channel, and node:test modules (bare or node:-prefixed) are supported"
+    }
+   ]
+  },
+  "<repo>/tests/fixtures/node-types/path-os.ts": {
+   "order": [
+    "<repo>/tests/fixtures/node-types/path-os.ts"
+   ],
+   "diags": []
+  },
+  "<repo>/tests/fixtures/node-types/stream-capture.ts": {
+   "order": [
+    "<repo>/tests/fixtures/node-types/stream-capture.ts"
+   ],
+   "diags": []
+  },
   "<repo>/tests/fixtures/npm/cases/abandoned-handles/main.ts": {
    "order": [
     "<repo>/tests/fixtures/npm/cases/abandoned-handles/main.ts"
@@ -6100,6 +6157,12 @@
    ],
    "diags": []
   },
+  "<repo>/tests/fixtures/npm/cases/workspace-unclean/main.ts": {
+   "order": [
+    "<repo>/tests/fixtures/npm/cases/workspace-unclean/main.ts"
+   ],
+   "diags": []
+  },
   "<repo>/tests/fixtures/npm/cases/zlib-shims/main.ts": {
    "order": [
     "<repo>/tests/fixtures/npm/cases/zlib-shims/main.ts"
@@ -6166,48 +6229,6 @@
      "hint": "set \"strictNullChecks\": true (or \"strict\": true) in the project tsconfig"
     }
    ]
-  },
-  "<repo>/tests/fixtures/node-types/argv-env.ts": {
-   "order": [
-    "<repo>/tests/fixtures/node-types/argv-env.ts"
-   ],
-   "diags": []
-  },
-  "<repo>/tests/fixtures/node-types/fenced.ts": {
-   "order": [
-    "<repo>/tests/fixtures/node-types/fenced.ts"
-   ],
-   "diags": []
-  },
-  "<repo>/tests/fixtures/node-types/import-fences.ts": {
-   "order": [
-    "<repo>/tests/fixtures/node-types/import-fences.ts"
-   ],
-   "diags": [
-    {
-     "code": "SC1010",
-     "message": "the 'v8' module is not supported yet",
-     "loc": {
-      "file": "<repo>/tests/fixtures/node-types/import-fences.ts",
-      "start": 422,
-      "end": 461
-     },
-     "milestone": "M4",
-     "hint": "relative imports (./file, ../dir/file), package.json-mediated project imports (#alias via the imports field, self-name references via exports), installed npm packages (their code runs under --dynamic), and the built-in fs, fs/promises, path, os, url, crypto, zlib, child_process, net, http, tls, https, http2, dgram, dns, util, util/types, string_decoder, readline, events, stream, buffer, assert, assert/strict, worker_threads, cluster, tty, async_hooks, timers, timers/promises, diagnostics_channel, and node:test modules (bare or node:-prefixed) are supported"
-    }
-   ]
-  },
-  "<repo>/tests/fixtures/node-types/path-os.ts": {
-   "order": [
-    "<repo>/tests/fixtures/node-types/path-os.ts"
-   ],
-   "diags": []
-  },
-  "<repo>/tests/fixtures/node-types/stream-capture.ts": {
-   "order": [
-    "<repo>/tests/fixtures/node-types/stream-capture.ts"
-   ],
-   "diags": []
   }
  }
 }
diff --git a/packages/compiler/test/ts7/resolver-parity.test.ts b/packages/compiler/test/ts7/resolver-parity.test.ts
index 4cf4d3351..c03d2af6c 100644
--- a/packages/compiler/test/ts7/resolver-parity.test.ts
+++ b/packages/compiler/test/ts7/resolver-parity.test.ts
@@ -20,6 +20,7 @@ import {
   resolveRelativeModule,
   resolveTypeDirective,
 } from "../../src/frontend/resolve.js";
+import { isRelativeSpecifier } from "../../src/frontend/shared.js";
 import { options5 } from "./harness.js";
 
 const repoRoot = join(import.meta.dirname, "../../../..");
@@ -96,7 +97,9 @@ test("relative and bare specifiers across the whole test tree resolve identicall
   for (const file of files) {
     for (const spec of specifiersOf(file)) {
       const reference = ts5.resolveModuleName(spec, file, OPTS, ts5.sys).resolvedModule ?? null;
-      if (spec.startsWith("./") || spec.startsWith("../")) {
+      // Bare '.' and '..' are the relative directory forms (SEMANTICS 362)
+      // — ts5 resolves them relative too, so they ride the relative arm.
+      if (isRelativeSpecifier(spec)) {
         relative++;
         const ours = resolveRelativeModule(file, spec);
         // The ONE deliberate relative-resolution delta: a PROJECT
diff --git a/tests/corpus/2390-dot-requires/main.cjs b/tests/corpus/2390-dot-requires/main.cjs
new file mode 100644
index 000000000..40c9a1518
--- /dev/null
+++ b/tests/corpus/2390-dot-requires/main.cjs
@@ -0,0 +1,7 @@
+// The bare '.' and '..' relative-specifier forms (Node's CJS resolution
+// treats them exactly like './' and '../' directory imports: the target
+// directory's package.json "main", else its index file) — vercel's CLI
+// spells `from '..'` at 41 sites, and the CJS require twin is the form
+// Node itself runs, so this case pins both lanes byte-for-byte.
+const child = require("./sub/child.cjs");
+console.log(child.report());
diff --git a/tests/corpus/2390-dot-requires/package.json b/tests/corpus/2390-dot-requires/package.json
new file mode 100644
index 000000000..d463d4ee7
--- /dev/null
+++ b/tests/corpus/2390-dot-requires/package.json
@@ -0,0 +1,4 @@
+{
+  "type": "commonjs",
+  "main": "./shared.cjs"
+}
diff --git a/tests/corpus/2390-dot-requires/shared.cjs b/tests/corpus/2390-dot-requires/shared.cjs
new file mode 100644
index 000000000..78c2fa68c
--- /dev/null
+++ b/tests/corpus/2390-dot-requires/shared.cjs
@@ -0,0 +1,3 @@
+// What `require('..')` answers from inside sub/: this directory's
+// package.json "main" target.
+module.exports = { tag: "parent-main" };
diff --git a/tests/corpus/2390-dot-requires/sub/child.cjs b/tests/corpus/2390-dot-requires/sub/child.cjs
new file mode 100644
index 000000000..bfd176c3d
--- /dev/null
+++ b/tests/corpus/2390-dot-requires/sub/child.cjs
@@ -0,0 +1,5 @@
+const parent = require(".."); // the case directory -> package.json main -> shared.cjs
+const self = require("."); // this directory -> sub/package.json main -> index.cjs
+module.exports.report = function () {
+  return parent.tag + ":" + self.name;
+};
diff --git a/tests/corpus/2390-dot-requires/sub/index.cjs b/tests/corpus/2390-dot-requires/sub/index.cjs
new file mode 100644
index 000000000..71e9f7508
--- /dev/null
+++ b/tests/corpus/2390-dot-requires/sub/index.cjs
@@ -0,0 +1 @@
+module.exports = { name: "sub-index" };
diff --git a/tests/corpus/2390-dot-requires/sub/package.json b/tests/corpus/2390-dot-requires/sub/package.json
new file mode 100644
index 000000000..dc6f3f4f8
--- /dev/null
+++ b/tests/corpus/2390-dot-requires/sub/package.json
@@ -0,0 +1,4 @@
+{
+  "type": "commonjs",
+  "main": "./index.cjs"
+}
diff --git a/tests/corpus/2391-default-builtin-imports/main.ts b/tests/corpus/2391-default-builtin-imports/main.ts
new file mode 100644
index 000000000..292a2c9e4
--- /dev/null
+++ b/tests/corpus/2391-default-builtin-imports/main.ts
@@ -0,0 +1,15 @@
+// DEFAULT imports of supported builtins in a TS source, under the
+// project's own adopted interop knob (esModuleInterop in this case's
+// tsconfig): Node's default export of a CJS builtin IS the module object,
+// so the binding exposes exactly the namespace-import surface — the same
+// tables `import * as fs` keys (vercel's CLI spells `import fs from
+// 'node:fs'` and `import path from 'path'` throughout). Without the
+// interop knob the SC1012 fence stands; with it, the checker accepted the
+// spelling and so does the lowering.
+import fs from "node:fs";
+import path from "path";
+import url from "node:url";
+
+console.log(fs.existsSync(process.cwd()) ? "cwd-exists" : "cwd-missing");
+console.log(path.join("a", "b"));
+console.log(url.fileURLToPath("file:///tmp/x.txt"));
diff --git a/tests/corpus/2391-default-builtin-imports/tsconfig.json b/tests/corpus/2391-default-builtin-imports/tsconfig.json
new file mode 100644
index 000000000..75cf960b2
--- /dev/null
+++ b/tests/corpus/2391-default-builtin-imports/tsconfig.json
@@ -0,0 +1,6 @@
+{
+  "compilerOptions": {
+    "strict": true,
+    "esModuleInterop": true
+  }
+}
diff --git a/tests/coverage-fixtures/cycle-inert-builtin/a.ts b/tests/coverage-fixtures/cycle-inert-builtin/a.ts
new file mode 100644
index 000000000..4492da20b
--- /dev/null
+++ b/tests/coverage-fixtures/cycle-inert-builtin/a.ts
@@ -0,0 +1,18 @@
+// One member of a benign import cycle whose top level calls a BUILTIN
+// with a BUILTIN function value as the argument (vercel's link.ts spells
+// `const readFile = promisify(fs.readFile)` at the top of a 5-cycle
+// cluster; Object.freeze(JSON.parse) is the same shape on scriptc's own
+// declared surface). No user code can run during the init window — the
+// callee and the callable argument are both dts-rooted — so the cycle
+// admission must hold and the module graph must load (the statement
+// itself may still be a statement-level blocker; that is a different
+// fence than SC1016).
+import { helper } from "./b";
+
+const frozenParse = Object.freeze(JSON.parse);
+
+export const A = "a";
+
+export function go(n: number): string {
+  return helper(n) + ":" + typeof frozenParse;
+}
diff --git a/tests/coverage-fixtures/cycle-inert-builtin/b.ts b/tests/coverage-fixtures/cycle-inert-builtin/b.ts
new file mode 100644
index 000000000..afcfca2a3
--- /dev/null
+++ b/tests/coverage-fixtures/cycle-inert-builtin/b.ts
@@ -0,0 +1,7 @@
+// Closes the cycle with a NAMED import read only from a function body
+// (the deferred position the admission demands).
+import { A } from "./a";
+
+export function helper(n: number): string {
+  return A + n;
+}
diff --git a/tests/coverage-fixtures/cycle-inert-builtin/main.ts b/tests/coverage-fixtures/cycle-inert-builtin/main.ts
new file mode 100644
index 000000000..f2cb2f56b
--- /dev/null
+++ b/tests/coverage-fixtures/cycle-inert-builtin/main.ts
@@ -0,0 +1,3 @@
+import { go } from "./a";
+
+console.log(go(3));
diff --git a/tests/coverage-fixtures/dot-parent/index.ts b/tests/coverage-fixtures/dot-parent/index.ts
new file mode 100644
index 000000000..dba86cb6d
--- /dev/null
+++ b/tests/coverage-fixtures/dot-parent/index.ts
@@ -0,0 +1,2 @@
+// What `from ".."` answers inside lib/: this directory's index module.
+export const banner = "parent-banner";
diff --git a/tests/coverage-fixtures/dot-parent/lib/child.ts b/tests/coverage-fixtures/dot-parent/lib/child.ts
new file mode 100644
index 000000000..7eb9d1091
--- /dev/null
+++ b/tests/coverage-fixtures/dot-parent/lib/child.ts
@@ -0,0 +1,11 @@
+// The bare '.' and '..' relative-specifier forms in the TS project
+// dialect (vercel's CLI: `from '..'` at 41 sites): '..' is the parent
+// DIRECTORY's index module, '.' this directory's own — exactly what the
+// project's bundler-resolution checker answers, so preflight and the
+// lowering resolve the same edges. (Node running raw TS would refuse a
+// directory import in ESM; the compiled program is the tsc dialect —
+// SEMANTICS.md's relative-specifier note.)
+import { banner } from "..";
+import { local } from ".";
+
+export const title = banner + ":" + local + "!";
diff --git a/tests/coverage-fixtures/dot-parent/lib/index.ts b/tests/coverage-fixtures/dot-parent/lib/index.ts
new file mode 100644
index 000000000..16cc02613
--- /dev/null
+++ b/tests/coverage-fixtures/dot-parent/lib/index.ts
@@ -0,0 +1 @@
+export const local = "lib-index";
diff --git a/tests/coverage-fixtures/dot-parent/main.ts b/tests/coverage-fixtures/dot-parent/main.ts
new file mode 100644
index 000000000..3926147e9
--- /dev/null
+++ b/tests/coverage-fixtures/dot-parent/main.ts
@@ -0,0 +1,3 @@
+import { title } from "./lib/child";
+
+console.log(title);
diff --git a/tests/fixtures/npm-static/nested/inner/app.ts b/tests/fixtures/npm-static/nested/inner/app.ts
new file mode 100644
index 000000000..f3cb33f52
--- /dev/null
+++ b/tests/fixtures/npm-static/nested/inner/app.ts
@@ -0,0 +1,5 @@
+import shouty from "shouty";
+
+export function run(): string {
+  return shouty("quiet words");
+}
diff --git a/tests/fixtures/npm-static/nested/inner/node_modules/shouty/index.d.ts b/tests/fixtures/npm-static/nested/inner/node_modules/shouty/index.d.ts
new file mode 100644
index 000000000..01daa28e7
--- /dev/null
+++ b/tests/fixtures/npm-static/nested/inner/node_modules/shouty/index.d.ts
@@ -0,0 +1 @@
+export default function shouty(text: string): string;
diff --git a/tests/fixtures/npm-static/nested/inner/node_modules/shouty/index.js b/tests/fixtures/npm-static/nested/inner/node_modules/shouty/index.js
new file mode 100644
index 000000000..5e647d64d
--- /dev/null
+++ b/tests/fixtures/npm-static/nested/inner/node_modules/shouty/index.js
@@ -0,0 +1,5 @@
+export default function shouty(text) {
+  let out = "";
+  for (const ch of text) out += ch === " " ? "_" : ch.toUpperCase();
+  return out + "!";
+}
diff --git a/tests/fixtures/npm-static/nested/inner/node_modules/shouty/package.json b/tests/fixtures/npm-static/nested/inner/node_modules/shouty/package.json
new file mode 100644
index 000000000..075fc3a27
--- /dev/null
+++ b/tests/fixtures/npm-static/nested/inner/node_modules/shouty/package.json
@@ -0,0 +1,6 @@
+{
+  "name": "shouty",
+  "version": "1.0.0",
+  "type": "module",
+  "exports": "./index.js"
+}
diff --git a/tests/fixtures/npm-static/nested/main.ts b/tests/fixtures/npm-static/nested/main.ts
new file mode 100644
index 000000000..07f91f1a9
--- /dev/null
+++ b/tests/fixtures/npm-static/nested/main.ts
@@ -0,0 +1,10 @@
+// The auto probe's resolution ANCHOR: shouty is installed only in
+// inner/'s own node_modules — visible from the importing file's walk-up,
+// invisible from this entry's (the pnpm-monorepo shape: vercel's CLI deps
+// live in packages/cli/node_modules while the driver entry sits outside).
+// auto must probe the runtime JS from the file that IMPORTS the package,
+// or eligibility answers "no runtime JS entry resolves" for a perfectly
+// ordinary install.
+import { run } from "./inner/app.ts";
+
+console.log(run());
diff --git a/tests/fixtures/npm/cases/workspace-unclean/main.ts b/tests/fixtures/npm/cases/workspace-unclean/main.ts
new file mode 100644
index 000000000..ea79c1abf
--- /dev/null
+++ b/tests/fixtures/npm/cases/workspace-unclean/main.ts
@@ -0,0 +1,10 @@
+// A workspace-linked UNTYPED package (main → shipped CJS, no .d.ts, the
+// @vercel/go shape): its realpath escapes node_modules, so allowJs pulls
+// the shipped JS into the checker's program — and the checker refuses
+// shapes Node runs fine. Those errors are the foreign-tsconfig story
+// (third-party shipped JS the program's author cannot fix); the package's
+// execution home is the island, so they never gate, and this program
+// must build AND agree with Node.
+import { describe } from "wsunclean";
+
+console.log(describe(21));
diff --git a/tests/fixtures/npm/cases/workspace-unclean/node_modules/wsunclean b/tests/fixtures/npm/cases/workspace-unclean/node_modules/wsunclean
new file mode 120000
index 000000000..b42711e9b
--- /dev/null
+++ b/tests/fixtures/npm/cases/workspace-unclean/node_modules/wsunclean
@@ -0,0 +1 @@
+../../../workspace/wsunclean
\ No newline at end of file
diff --git a/tests/fixtures/npm/workspace/wsunclean/dist/index.js b/tests/fixtures/npm/workspace/wsunclean/dist/index.js
new file mode 100644
index 000000000..7028a38a3
--- /dev/null
+++ b/tests/fixtures/npm/workspace/wsunclean/dist/index.js
@@ -0,0 +1,22 @@
+"use strict";
+// The bundled-dist diet: shapes tsc's checkJs REFUSES but Node runs
+// happily (@vercel/go's ncc bundle carries dozens of each — a function
+// binding reassigned, an executor-less-looking resolve(), an empty if
+// body). The package ships NO declarations and its realpath lies OUTSIDE
+// node_modules (the workspace link), so the checker's program pulls this
+// file in and finds the errors — which must never gate: the island is
+// this file's one execution home.
+function greet(name) {
+  return "hi " + name;
+}
+greet = function (name) {
+  return "hello " + name;
+};
+if (process.env.WSUNCLEAN_NEVER_SET) ;
+var ready = new Promise(function (resolve) {
+  resolve();
+});
+exports.describe = function (n) {
+  return "wsunclean:" + greet("go") + ":" + n * 2;
+};
+exports.ready = ready;
diff --git a/tests/fixtures/npm/workspace/wsunclean/package.json b/tests/fixtures/npm/workspace/wsunclean/package.json
new file mode 100644
index 000000000..bd79dda17
--- /dev/null
+++ b/tests/fixtures/npm/workspace/wsunclean/package.json
@@ -0,0 +1,5 @@
+{
+  "name": "wsunclean",
+  "version": "1.0.0",
+  "main": "./dist/index"
+}
diff --git a/tests/harness/coverage.test.ts b/tests/harness/coverage.test.ts
index 190afd2ed..1046b7cf2 100644
--- a/tests/harness/coverage.test.ts
+++ b/tests/harness/coverage.test.ts
@@ -127,6 +127,26 @@ test("type errors render the same code frame a build prints", () => {
   expect(out).toContain("^");
 });
 
+test("bare '.' and '..' imports are relative edges (the vercel-CLI dialect)", () => {
+  // `from '..'` / `from '.'` resolve as directory imports to the target's
+  // index module — exactly what the project's bundler-resolution checker
+  // answered — so the graph loads and everything compiles statically.
+  const out = report(fixture("dot-parent/main.ts"));
+  expect(out).toContain("(100%)");
+  expect(out).toContain("fully static");
+});
+
+test("a cycle whose top level calls a builtin with a builtin function value is admitted", () => {
+  // vercel's link.ts cluster: `promisify(fs.readFile)` at a cycle member's
+  // top level. Callee and callable argument are both dts-rooted — no user
+  // code can run in the init window — so no SC1016 and the analysis
+  // renders statement counts (the statement itself may stay a
+  // statement-LEVEL blocker; that is a different fence).
+  const out = report(fixture("cycle-inert-builtin/main.ts"));
+  expect(out).not.toContain("circular imports");
+  expect(out).toContain("statements analyzed");
+});
+
 test("every corpus program is 100% static (corpus and coverage agree)", async () => {
   // The differential corpus compiles by definition; coverage must agree.
   // `// @dynamic` programs compile under --dynamic, so analyze them that way.
diff --git a/tests/harness/npm-static.test.ts b/tests/harness/npm-static.test.ts
index b3dc36613..4d30ac438 100644
--- a/tests/harness/npm-static.test.ts
+++ b/tests/harness/npm-static.test.ts
@@ -50,15 +50,15 @@ async function runBinary(cmd: string, args: string[]): Promise<RunResult> {
 /** Compile one pilot statically (no --dynamic — the whole point) with the
  * named packages opted in; cache-keyed over the program and the vendored
  * packages. */
-async function buildStatic(entry: string, npmStatic: string[]): Promise<string> {
+async function buildStatic(entry: string, npmStatic: string[] | "auto"): Promise<string> {
   const hash = createHash("sha256");
   const inputs = [
     entry,
-    ...globSync(join(pilotRoot, "node_modules/**/*.{js,mjs,cjs,json,d.ts}")).sort(),
+    ...globSync(join(pilotRoot, "**/node_modules/**/*.{js,mjs,cjs,json,d.ts}")).sort(),
   ];
   for (const f of inputs) hash.update(f).update(readFileSync(f));
   const key = hash
-    .update(npmStatic.join(","))
+    .update(npmStatic === "auto" ? "auto" : npmStatic.join(","))
     .update(sanitize ? "san" : "plain")
     .digest("hex")
     .slice(0, 16);
@@ -119,6 +119,26 @@ describe(`npm-static pilots${sanitize ? " (sanitized)" : ""}`, () => {
     expect(coverage.stats.statementsFailed).toBe(0);
   }, 120_000);
 
+  // Auto's runtime-JS probe anchors at the IMPORTING file, not the entry:
+  // shouty is installed only in inner/'s node_modules (the pnpm-monorepo
+  // shape — vercel's CLI deps live in packages/cli/node_modules while the
+  // analysis driver sits outside every package realm), so an entry-anchored
+  // probe answers "no runtime JS entry resolves" for an ordinary install.
+  test("--npm-static=auto probes runtime JS from the importing file's realm", async () => {
+    const entry = join(pilotRoot, "nested/main.ts");
+    const { coverage } = analyze(entry, { npmStatic: "auto" });
+    expect(coverage.npmStatic).toEqual([{ package: "shouty", status: "static" }]);
+    expect(coverage.preflightFailed).toBe(false);
+    expect(coverage.stats.statementsFailed).toBe(0);
+    const binary = await buildStatic(entry, "auto");
+    const [nodeRes, nativeRes] = await Promise.all([
+      runBinary("node", [entry]),
+      runBinary(binary, []),
+    ]);
+    expect(nativeRes.stdout.toString("utf8")).toBe(nodeRes.stdout.toString("utf8"));
+    expect(nativeRes.exitCode).toBe(nodeRes.exitCode);
+  }, 120_000);
+
   // Auto refuses ms: it ships no own .d.ts (the declared-claim criterion),
   // so the import keeps today's story — and the explicit opt-in below is
   // the user's override.
diff --git a/tests/harness/project-config.test.ts b/tests/harness/project-config.test.ts
index b53acd34c..16077a95c 100644
--- a/tests/harness/project-config.test.ts
+++ b/tests/harness/project-config.test.ts
@@ -194,3 +194,20 @@ test("no-types-node: a bare project outside the repo compiles on the fallback de
   const { stdout } = await execFileAsync(result.binaryPath);
   expect(stdout).toBe("hi bare\n");
 });
+
+test("dot-parent: bare '.' and '..' imports build and run (the TS project dialect)", async () => {
+  // The vercel-CLI spelling (`from '..'` for a parent directory's index):
+  // scriptc-only — Node refuses directory imports when running raw TS as
+  // ESM, but the compiled program follows the project's own bundler-
+  // resolution dialect (the SEMANTICS.md relative-specifier note).
+  const outDir = outDirFor("dot-parent");
+  const result = await compile(join(repoRoot, "tests/coverage-fixtures/dot-parent/main.ts"), {
+    outPath: join(outDir, "main"),
+    outDir,
+    sanitize,
+  });
+  expect(result.ok, !result.ok ? JSON.stringify(result.diagnostics, null, 2) : "").toBe(true);
+  if (!result.ok) return;
+  const { stdout } = await execFileAsync(result.binaryPath);
+  expect(stdout).toBe("parent-banner:lib-index!\n");
+});