fix(plugin-sdk): fall back from dist facade overrides to source surfaces

src/plugins/public-surface-runtime.test.ts

@@ -5,6 +5,7 @@ import { afterEach, describe, expect, it } from "vitest";
 import {
   PUBLIC_SURFACE_SOURCE_EXTENSIONS,
   normalizeBundledPluginArtifactSubpath,
+  resolveBundledPluginPublicSurfacePath,
   resolveBundledPluginSourcePublicSurfacePath,
 } from "./public-surface-runtime.js";
 
@@ -49,6 +50,25 @@ describe("bundled plugin public surface runtime", () => {
     ).toBe(modulePath);
   });
 
+  it("falls back from package dist overrides to the source extension tree", () => {
+    const packageRoot = createTempDir();
+    const sourceModulePath = path.join(packageRoot, "extensions", "demo", "api.ts");
+    fs.mkdirSync(path.dirname(sourceModulePath), { recursive: true });
+    fs.writeFileSync(sourceModulePath, "export const marker = 'source';\n", "utf8");
+
+    const bundledPluginsDir = path.join(packageRoot, "dist", "extensions");
+    fs.mkdirSync(path.join(bundledPluginsDir, "demo"), { recursive: true });
+
+    expect(
+      resolveBundledPluginPublicSurfacePath({
+        rootDir: packageRoot,
+        bundledPluginsDir,
+        dirName: "demo",
+        artifactBasename: "api.js",
+      }),
+    ).toBe(sourceModulePath);
+  });
+
   it("allows plugin-local nested artifact paths", () => {
     expect(normalizeBundledPluginArtifactSubpath("src/outbound-adapter.js")).toBe(
       "src/outbound-adapter.js",

src/plugins/public-surface-runtime.ts

@@ -58,6 +58,28 @@ export function resolveBundledPluginSourcePublicSurfacePath(params: {
   return null;
 }
 
+function resolvePackageSourceFallbackForBundledDir(params: {
+  rootDir: string;
+  bundledPluginsDir: string;
+  dirName: string;
+  artifactBasename: string;
+}): string | null {
+  const normalizedBundledDir = path.resolve(params.bundledPluginsDir);
+  const normalizedRootDir = path.resolve(params.rootDir);
+  const packageBundledDirs = [
+    path.join(normalizedRootDir, "dist", "extensions"),
+    path.join(normalizedRootDir, "dist-runtime", "extensions"),
+  ];
+  if (!packageBundledDirs.includes(normalizedBundledDir)) {
+    return null;
+  }
+  return resolveBundledPluginSourcePublicSurfacePath({
+    sourceRoot: path.join(normalizedRootDir, "extensions"),
+    dirName: params.dirName,
+    artifactBasename: params.artifactBasename,
+  });
+}
+
 export function resolveBundledPluginPublicSurfacePath(params: {
   rootDir: string;
   dirName: string;
@@ -75,11 +97,19 @@ export function resolveBundledPluginPublicSurfacePath(params: {
     if (fs.existsSync(explicitBuiltCandidate)) {
       return explicitBuiltCandidate;
     }
-    return resolveBundledPluginSourcePublicSurfacePath({
-      sourceRoot: explicitBundledPluginsDir,
-      dirName: params.dirName,
-      artifactBasename,
-    });
+    return (
+      resolveBundledPluginSourcePublicSurfacePath({
+        sourceRoot: explicitBundledPluginsDir,
+        dirName: params.dirName,
+        artifactBasename,
+      }) ??
+      resolvePackageSourceFallbackForBundledDir({
+        rootDir: params.rootDir,
+        bundledPluginsDir: explicitBundledPluginsDir,
+        dirName: params.dirName,
+        artifactBasename,
+      })
+    );
   }
 
   for (const candidate of [