From 1c90ad084441d32472dbba7bf13ee44c83c1368d Mon Sep 17 00:00:00 2001
From: Max B <max@tfq.at>
Date: Sun, 23 Aug 2026 21:45:17 +0200
Subject: [PATCH] fix(dynamic): stub non-compilable dynamic imports to
 Promise.resolve({})
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Two related gaps in --dynamic mode:

1. .tsx files (JSX): `dynamicImportProgramTargetOf` now returns null for
   .tsx files, keeping them out of the compiled module graph. The
   `lowerOwnModuleImport` path then stubs the import to
   `Promise.resolve({})` via the new `dep !== null && L.dynamic` branch.

2. Program modules with no builder: when a module IS in the checker's
   program (dep !== null) but has no compilation story — no %init was
   produced, e.g. a module that was explicitly excluded from the compiled
   graph — the compiler previously emitted SC1090 unconditionally. In
   --dynamic mode, this now stubs to `Promise.resolve({})` instead.
   Callers that destructure the namespace receive `undefined` for every
   export, which is the correct behavior when the module is not
   reachable from the native binary.

These two changes together cover the common --dynamic pattern of lazy
module loading where some targets are intentionally not compiled
natively (JSX widgets, server-only modules).
---
 .../compiler/src/frontend/lowering/lower-island.ts  | 13 +++++++++++++
 .../compiler/src/frontend/lowering/lower-modules.ts |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/packages/compiler/src/frontend/lowering/lower-island.ts b/packages/compiler/src/frontend/lowering/lower-island.ts
index 467490f2b..35e266145 100644
--- a/packages/compiler/src/frontend/lowering/lower-island.ts
+++ b/packages/compiler/src/frontend/lowering/lower-island.ts
@@ -2832,6 +2832,19 @@ export function lowerStaticReadableStreamReaderCall(
     }
     const builder = dep !== null ? dynNsBuilderOf(L, dep, loc) : null;
     if (builder === null) {
+      // In --dynamic mode, a module that is in the program graph but has no
+      // compilation story (excluded from the compiled module graph, or contains
+      // features the native compiler cannot lower) resolves to an empty namespace
+      // stub rather than emitting SC1090. The JSVAL island absorbs the namespace
+      // object; callers that destructure it receive `undefined` for every export,
+      // which is the correct runtime behavior when the module delegates to the JS
+      // engine or is not reachable from the native binary.
+      if (dep !== null && L.dynamic) {
+        const promiseCtor: IrExpr = { kind: "jsOp", op: "globalGet", name: "Promise", args: [], type: JSVAL, loc };
+        const emptyObj: IrExpr = { kind: "jsOp", op: "objLit", args: [], type: JSVAL, loc };
+        const resolved: IrExpr = { kind: "jsOp", op: "callMethod", name: "resolve", args: [promiseCtor, emptyObj], type: JSVAL, loc };
+        return { kind: "jsBridgePromise", value: resolved, type: { kind: "promise", inner: JSVAL }, loc };
+      }
       L.unsupported(
         "SC1090",
         call,
diff --git a/packages/compiler/src/frontend/lowering/lower-modules.ts b/packages/compiler/src/frontend/lowering/lower-modules.ts
index a0006bf3a..0a2e9d814 100644
--- a/packages/compiler/src/frontend/lowering/lower-modules.ts
+++ b/packages/compiler/src/frontend/lowering/lower-modules.ts
@@ -81,6 +81,9 @@ export interface FileParts {
     if (!dep || dep.isDeclarationFile) return null;
     if (dep.fileName.endsWith(".json") || dep.fileName.endsWith(".cts")) return null;
     if (isCjsJsFile(dep)) return null;
+    // JSX files are not supported by scriptc's native compiler.
+    // Dynamic imports of .tsx/.jsx files resolve to an empty namespace stub at runtime.
+    if (dep.fileName.endsWith(".tsx") || dep.fileName.endsWith(".jsx")) return null;
     return dep;
   }