diff --git a/demos/ai-chat/.gitignore b/demos/ai-chat/.gitignore
index 7fc49260..abb3b440 100644
--- a/demos/ai-chat/.gitignore
+++ b/demos/ai-chat/.gitignore
@@ -12,3 +12,5 @@
 # misc
 .DS_Store
 *.pem
+.btst-stack-src/
+.btst-stack-ui/
diff --git a/demos/ai-chat/app/globals.css b/demos/ai-chat/app/globals.css
index 23035e76..df29e2ce 100644
--- a/demos/ai-chat/app/globals.css
+++ b/demos/ai-chat/app/globals.css
@@ -2,6 +2,15 @@
 @import "tw-animate-css";
 @import "@btst/stack/plugins/ai-chat/css";
 @import "@btst/stack/plugins/route-docs/css";
+/* WebContainers workaround: the WASM Tailwind scanner cannot traverse node_modules
+ * (https://github.com/tailwindlabs/tailwindcss/issues/18418). copy-stack-src.mjs
+ * (run via predev/prebuild) copies @btst/stack/src outside node_modules so Tailwind
+ * can scan it. Safe to remove once the upstream bug is fixed. */
+@source "./.btst-stack-src/**/*.{ts,tsx}";
+@source "./.btst-stack-ui/**/*.{ts,tsx}";
+/* Monorepo fallback: direct source path used in local development */
+@source "../../../packages/stack/src/**/*.{ts,tsx}";
+@source "../../../packages/ui/src/**/*.{ts,tsx}";
 
 @custom-variant dark (&:is(.dark *));
 
diff --git a/demos/ai-chat/copy-stack-src.mjs b/demos/ai-chat/copy-stack-src.mjs
new file mode 100644
index 00000000..dc457f07
--- /dev/null
+++ b/demos/ai-chat/copy-stack-src.mjs
@@ -0,0 +1,45 @@
+#!/usr/bin/env node
+/**
+ * Copies @btst/stack/src outside of node_modules so Tailwind's WASM scanner
+ * (used in WebContainers/StackBlitz) can traverse it.
+ *
+ * The WASM oxide scanner cannot scan inside node_modules due to a bug:
+ * https://github.com/tailwindlabs/tailwindcss/issues/18418
+ *
+ * Run automatically via the predev/prebuild npm lifecycle hooks.
+ */
+import { cp, mkdir, rm } from "fs/promises";
+import { existsSync } from "fs";
+
+const src = "node_modules/@btst/stack/src";
+const dest = ".btst-stack-src";
+
+const uiSrc = "node_modules/@btst/stack/dist/packages/ui";
+const uiDest = ".btst-stack-ui";
+
+if (!existsSync(src)) {
+	// Likely running in the monorepo where the workspace symlink does not expose
+	// src/ — fall back gracefully; @source paths in globals.css cover this case.
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/src not found, skipping",
+	);
+	process.exit(0);
+}
+
+await rm(dest, { recursive: true, force: true });
+await mkdir(dest, { recursive: true });
+await cp(src, dest, { recursive: true });
+console.log("[copy-stack-src] copied @btst/stack/src → .btst-stack-src");
+
+if (existsSync(uiSrc)) {
+	await rm(uiDest, { recursive: true, force: true });
+	await mkdir(uiDest, { recursive: true });
+	await cp(uiSrc, uiDest, { recursive: true });
+	console.log(
+		"[copy-stack-src] copied @btst/stack/dist/packages/ui → .btst-stack-ui",
+	);
+} else {
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/dist/packages/ui not found, skipping",
+	);
+}
diff --git a/demos/ai-chat/package.json b/demos/ai-chat/package.json
index 116c12b9..3386dc5d 100644
--- a/demos/ai-chat/package.json
+++ b/demos/ai-chat/package.json
@@ -3,15 +3,15 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "next dev",
-    "build": "next build",
+    "dev": "node copy-stack-src.mjs && next dev",
+    "build": "node copy-stack-src.mjs && next build",
     "start": "next start"
   },
   "dependencies": {
     "@ai-sdk/openai": "^3.0.41",
     "@ai-sdk/react": "^3.0.118",
     "@btst/adapter-memory": "^2.0.3",
-    "@btst/stack": "^2.5.1",
+    "@btst/stack": "^2.5.2",
     "@btst/yar": "^1.2.0",
     "@hookform/resolvers": "^5.2.2",
     "@radix-ui/react-dialog": "^1.1.15",
@@ -29,7 +29,7 @@
     "highlight.js": "^11.11.1",
     "katex": "^0.16.35",
     "lucide-react": "^0.577.0",
-    "next": "16.1.6",
+    "next": "15.4.1",
     "next-themes": "^0.4.6",
     "radix-ui": "^1.4.3",
     "react": "19.2.3",
diff --git a/demos/blog/.gitignore b/demos/blog/.gitignore
index 7fc49260..abb3b440 100644
--- a/demos/blog/.gitignore
+++ b/demos/blog/.gitignore
@@ -12,3 +12,5 @@
 # misc
 .DS_Store
 *.pem
+.btst-stack-src/
+.btst-stack-ui/
diff --git a/demos/blog/app/globals.css b/demos/blog/app/globals.css
index 0640acda..2829890b 100644
--- a/demos/blog/app/globals.css
+++ b/demos/blog/app/globals.css
@@ -2,6 +2,15 @@
 @import "tw-animate-css";
 @import "@btst/stack/plugins/blog/css";
 @import "@btst/stack/plugins/route-docs/css";
+/* WebContainers workaround: the WASM Tailwind scanner cannot traverse node_modules
+ * (https://github.com/tailwindlabs/tailwindcss/issues/18418). copy-stack-src.mjs
+ * (run via predev/prebuild) copies @btst/stack/src outside node_modules so Tailwind
+ * can scan it. Safe to remove once the upstream bug is fixed. */
+@source "./.btst-stack-src/**/*.{ts,tsx}";
+@source "./.btst-stack-ui/**/*.{ts,tsx}";
+/* Monorepo fallback: direct source path used in local development */
+@source "../../../packages/stack/src/**/*.{ts,tsx}";
+@source "../../../packages/ui/src/**/*.{ts,tsx}";
 
 @custom-variant dark (&:is(.dark *));
 
diff --git a/demos/blog/copy-stack-src.mjs b/demos/blog/copy-stack-src.mjs
new file mode 100644
index 00000000..dc457f07
--- /dev/null
+++ b/demos/blog/copy-stack-src.mjs
@@ -0,0 +1,45 @@
+#!/usr/bin/env node
+/**
+ * Copies @btst/stack/src outside of node_modules so Tailwind's WASM scanner
+ * (used in WebContainers/StackBlitz) can traverse it.
+ *
+ * The WASM oxide scanner cannot scan inside node_modules due to a bug:
+ * https://github.com/tailwindlabs/tailwindcss/issues/18418
+ *
+ * Run automatically via the predev/prebuild npm lifecycle hooks.
+ */
+import { cp, mkdir, rm } from "fs/promises";
+import { existsSync } from "fs";
+
+const src = "node_modules/@btst/stack/src";
+const dest = ".btst-stack-src";
+
+const uiSrc = "node_modules/@btst/stack/dist/packages/ui";
+const uiDest = ".btst-stack-ui";
+
+if (!existsSync(src)) {
+	// Likely running in the monorepo where the workspace symlink does not expose
+	// src/ — fall back gracefully; @source paths in globals.css cover this case.
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/src not found, skipping",
+	);
+	process.exit(0);
+}
+
+await rm(dest, { recursive: true, force: true });
+await mkdir(dest, { recursive: true });
+await cp(src, dest, { recursive: true });
+console.log("[copy-stack-src] copied @btst/stack/src → .btst-stack-src");
+
+if (existsSync(uiSrc)) {
+	await rm(uiDest, { recursive: true, force: true });
+	await mkdir(uiDest, { recursive: true });
+	await cp(uiSrc, uiDest, { recursive: true });
+	console.log(
+		"[copy-stack-src] copied @btst/stack/dist/packages/ui → .btst-stack-ui",
+	);
+} else {
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/dist/packages/ui not found, skipping",
+	);
+}
diff --git a/demos/blog/lib/seed.ts b/demos/blog/lib/seed.ts
index 1ebde118..8b952314 100644
--- a/demos/blog/lib/seed.ts
+++ b/demos/blog/lib/seed.ts
@@ -1,11 +1,6 @@
 import type { Adapter } from "@btst/stack/plugins/api";
 
-let seeded = false;
-
 export async function seedBlogData(adapter: Adapter) {
-	if (seeded) return;
-	seeded = true;
-
 	try {
 		// Check if posts already exist
 		const existing = await adapter.findMany({ model: "post", limit: 1 });
diff --git a/demos/blog/lib/stack.ts b/demos/blog/lib/stack.ts
index 934d6b4a..44286f5a 100644
--- a/demos/blog/lib/stack.ts
+++ b/demos/blog/lib/stack.ts
@@ -4,8 +4,11 @@ import { blogBackendPlugin } from "@btst/stack/plugins/blog/api";
 import { openApiBackendPlugin } from "@btst/stack/plugins/open-api/api";
 import { seedBlogData } from "./seed";
 
+// Persist stack and seed promise on `global` so Next.js module re-evaluations
+// (HMR, per-request server components) don't create a second instance or re-run the seed.
 const globalForStack = global as typeof global & {
 	__btst_stack__?: ReturnType<typeof createStack>;
+	__btst_seeded__?: Promise<void>;
 };
 
 function createStack() {
@@ -25,7 +28,8 @@ function createStack() {
 
 export const myStack = (globalForStack.__btst_stack__ ??= createStack());
 
-// Seed demo data after singleton is created
-seedBlogData(myStack.adapter).catch(console.error);
+globalForStack.__btst_seeded__ ??= seedBlogData(myStack.adapter).catch(
+	console.error,
+);
 
 export const { handler, dbSchema } = myStack;
diff --git a/demos/blog/package.json b/demos/blog/package.json
index 798f9f3b..3ed8d559 100644
--- a/demos/blog/package.json
+++ b/demos/blog/package.json
@@ -3,14 +3,14 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "next dev",
-    "build": "next build",
+    "dev": "node copy-stack-src.mjs && next dev",
+    "build": "node copy-stack-src.mjs && next build",
     "start": "next start"
   },
   "dependencies": {
     "@ai-sdk/react": "^3.0.118",
     "@btst/adapter-memory": "^2.0.3",
-    "@btst/stack": "^2.5.1",
+    "@btst/stack": "^2.5.2",
     "@btst/yar": "^1.2.0",
     "@hookform/resolvers": "^5.2.2",
     "@radix-ui/react-dialog": "^1.1.15",
@@ -28,7 +28,7 @@
     "highlight.js": "^11.11.1",
     "katex": "^0.16.35",
     "lucide-react": "^0.577.0",
-    "next": "16.1.6",
+    "next": "15.4.1",
     "next-themes": "^0.4.6",
     "radix-ui": "^1.4.3",
     "react": "19.2.3",
diff --git a/demos/cms/.gitignore b/demos/cms/.gitignore
index 7fc49260..abb3b440 100644
--- a/demos/cms/.gitignore
+++ b/demos/cms/.gitignore
@@ -12,3 +12,5 @@
 # misc
 .DS_Store
 *.pem
+.btst-stack-src/
+.btst-stack-ui/
diff --git a/demos/cms/app/globals.css b/demos/cms/app/globals.css
index 62dce9a0..5b5e5234 100644
--- a/demos/cms/app/globals.css
+++ b/demos/cms/app/globals.css
@@ -2,6 +2,15 @@
 @import "tw-animate-css";
 @import "@btst/stack/plugins/cms/css";
 @import "@btst/stack/plugins/route-docs/css";
+/* WebContainers workaround: the WASM Tailwind scanner cannot traverse node_modules
+ * (https://github.com/tailwindlabs/tailwindcss/issues/18418). copy-stack-src.mjs
+ * (run via predev/prebuild) copies @btst/stack/src outside node_modules so Tailwind
+ * can scan it. Safe to remove once the upstream bug is fixed. */
+@source "./.btst-stack-src/**/*.{ts,tsx}";
+@source "./.btst-stack-ui/**/*.{ts,tsx}";
+/* Monorepo fallback: direct source path used in local development */
+@source "../../../packages/stack/src/**/*.{ts,tsx}";
+@source "../../../packages/ui/src/**/*.{ts,tsx}";
 
 @custom-variant dark (&:is(.dark *));
 
diff --git a/demos/cms/copy-stack-src.mjs b/demos/cms/copy-stack-src.mjs
new file mode 100644
index 00000000..dc457f07
--- /dev/null
+++ b/demos/cms/copy-stack-src.mjs
@@ -0,0 +1,45 @@
+#!/usr/bin/env node
+/**
+ * Copies @btst/stack/src outside of node_modules so Tailwind's WASM scanner
+ * (used in WebContainers/StackBlitz) can traverse it.
+ *
+ * The WASM oxide scanner cannot scan inside node_modules due to a bug:
+ * https://github.com/tailwindlabs/tailwindcss/issues/18418
+ *
+ * Run automatically via the predev/prebuild npm lifecycle hooks.
+ */
+import { cp, mkdir, rm } from "fs/promises";
+import { existsSync } from "fs";
+
+const src = "node_modules/@btst/stack/src";
+const dest = ".btst-stack-src";
+
+const uiSrc = "node_modules/@btst/stack/dist/packages/ui";
+const uiDest = ".btst-stack-ui";
+
+if (!existsSync(src)) {
+	// Likely running in the monorepo where the workspace symlink does not expose
+	// src/ — fall back gracefully; @source paths in globals.css cover this case.
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/src not found, skipping",
+	);
+	process.exit(0);
+}
+
+await rm(dest, { recursive: true, force: true });
+await mkdir(dest, { recursive: true });
+await cp(src, dest, { recursive: true });
+console.log("[copy-stack-src] copied @btst/stack/src → .btst-stack-src");
+
+if (existsSync(uiSrc)) {
+	await rm(uiDest, { recursive: true, force: true });
+	await mkdir(uiDest, { recursive: true });
+	await cp(uiSrc, uiDest, { recursive: true });
+	console.log(
+		"[copy-stack-src] copied @btst/stack/dist/packages/ui → .btst-stack-ui",
+	);
+} else {
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/dist/packages/ui not found, skipping",
+	);
+}
diff --git a/demos/cms/lib/seed.ts b/demos/cms/lib/seed.ts
index 44788c88..727001a8 100644
--- a/demos/cms/lib/seed.ts
+++ b/demos/cms/lib/seed.ts
@@ -1,9 +1,4 @@
-let seeded = false;
-
 export async function seedCmsData(api: any) {
-	if (seeded) return;
-	seeded = true;
-
 	try {
 		// Check if articles already exist (getAllContentItems also calls ensureSynced)
 		const existing = await api.cms.getAllContentItems("article", { limit: 1 });
diff --git a/demos/cms/lib/stack.ts b/demos/cms/lib/stack.ts
index d311a77d..23dc8835 100644
--- a/demos/cms/lib/stack.ts
+++ b/demos/cms/lib/stack.ts
@@ -4,8 +4,11 @@ import { cmsBackendPlugin } from "@btst/stack/plugins/cms/api";
 import { openApiBackendPlugin } from "@btst/stack/plugins/open-api/api";
 import { z } from "zod";
 import { seedCmsData } from "./seed";
+// Persist stack and seed promise on `global` so Next.js module re-evaluations
+// (HMR, per-request server components) don't create a second instance or re-run the seed.
 const globalForStack = global as typeof global & {
 	__btst_stack__?: ReturnType<typeof createStack>;
+	__btst_seeded__?: Promise<void>;
 };
 
 // Simple article content type
@@ -45,7 +48,8 @@ function createStack() {
 
 export const myStack = (globalForStack.__btst_stack__ ??= createStack());
 
-// Seed demo data — uses api.cms.createContentItem which calls ensureSynced internally
-seedCmsData(myStack.api).catch(console.error);
+globalForStack.__btst_seeded__ ??= seedCmsData(myStack.api).catch(
+	console.error,
+);
 
 export const { handler, dbSchema } = myStack;
diff --git a/demos/cms/package.json b/demos/cms/package.json
index e0da6aff..0491f309 100644
--- a/demos/cms/package.json
+++ b/demos/cms/package.json
@@ -3,14 +3,14 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "next dev",
-    "build": "next build",
+    "dev": "node copy-stack-src.mjs && next dev",
+    "build": "node copy-stack-src.mjs && next build",
     "start": "next start"
   },
   "dependencies": {
     "@ai-sdk/react": "^3.0.118",
     "@btst/adapter-memory": "^2.0.3",
-    "@btst/stack": "^2.5.1",
+    "@btst/stack": "^2.5.2",
     "@btst/yar": "^1.2.0",
     "@dnd-kit/core": "^6.3.1",
     "@dnd-kit/sortable": "^10.0.0",
@@ -45,7 +45,7 @@
     "highlight.js": "^11.11.1",
     "katex": "^0.16.35",
     "lucide-react": "^0.577.0",
-    "next": "16.1.6",
+    "next": "15.4.1",
     "next-themes": "^0.4.6",
     "radix-ui": "^1.4.3",
     "react": "19.2.3",
diff --git a/demos/form-builder/.gitignore b/demos/form-builder/.gitignore
index 7fc49260..abb3b440 100644
--- a/demos/form-builder/.gitignore
+++ b/demos/form-builder/.gitignore
@@ -12,3 +12,5 @@
 # misc
 .DS_Store
 *.pem
+.btst-stack-src/
+.btst-stack-ui/
diff --git a/demos/form-builder/app/globals.css b/demos/form-builder/app/globals.css
index df1dbb9c..dc6bac34 100644
--- a/demos/form-builder/app/globals.css
+++ b/demos/form-builder/app/globals.css
@@ -2,6 +2,15 @@
 @import "tw-animate-css";
 @import "@btst/stack/plugins/form-builder/css";
 @import "@btst/stack/plugins/route-docs/css";
+/* WebContainers workaround: the WASM Tailwind scanner cannot traverse node_modules
+ * (https://github.com/tailwindlabs/tailwindcss/issues/18418). copy-stack-src.mjs
+ * (run via predev/prebuild) copies @btst/stack/src outside node_modules so Tailwind
+ * can scan it. Safe to remove once the upstream bug is fixed. */
+@source "./.btst-stack-src/**/*.{ts,tsx}";
+@source "./.btst-stack-ui/**/*.{ts,tsx}";
+/* Monorepo fallback: direct source path used in local development */
+@source "../../../packages/stack/src/**/*.{ts,tsx}";
+@source "../../../packages/ui/src/**/*.{ts,tsx}";
 
 @custom-variant dark (&:is(.dark *));
 
diff --git a/demos/form-builder/copy-stack-src.mjs b/demos/form-builder/copy-stack-src.mjs
new file mode 100644
index 00000000..dc457f07
--- /dev/null
+++ b/demos/form-builder/copy-stack-src.mjs
@@ -0,0 +1,45 @@
+#!/usr/bin/env node
+/**
+ * Copies @btst/stack/src outside of node_modules so Tailwind's WASM scanner
+ * (used in WebContainers/StackBlitz) can traverse it.
+ *
+ * The WASM oxide scanner cannot scan inside node_modules due to a bug:
+ * https://github.com/tailwindlabs/tailwindcss/issues/18418
+ *
+ * Run automatically via the predev/prebuild npm lifecycle hooks.
+ */
+import { cp, mkdir, rm } from "fs/promises";
+import { existsSync } from "fs";
+
+const src = "node_modules/@btst/stack/src";
+const dest = ".btst-stack-src";
+
+const uiSrc = "node_modules/@btst/stack/dist/packages/ui";
+const uiDest = ".btst-stack-ui";
+
+if (!existsSync(src)) {
+	// Likely running in the monorepo where the workspace symlink does not expose
+	// src/ — fall back gracefully; @source paths in globals.css cover this case.
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/src not found, skipping",
+	);
+	process.exit(0);
+}
+
+await rm(dest, { recursive: true, force: true });
+await mkdir(dest, { recursive: true });
+await cp(src, dest, { recursive: true });
+console.log("[copy-stack-src] copied @btst/stack/src → .btst-stack-src");
+
+if (existsSync(uiSrc)) {
+	await rm(uiDest, { recursive: true, force: true });
+	await mkdir(uiDest, { recursive: true });
+	await cp(uiSrc, uiDest, { recursive: true });
+	console.log(
+		"[copy-stack-src] copied @btst/stack/dist/packages/ui → .btst-stack-ui",
+	);
+} else {
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/dist/packages/ui not found, skipping",
+	);
+}
diff --git a/demos/form-builder/lib/seed.ts b/demos/form-builder/lib/seed.ts
index a8166a0f..21738fda 100644
--- a/demos/form-builder/lib/seed.ts
+++ b/demos/form-builder/lib/seed.ts
@@ -1,11 +1,6 @@
 import type { Adapter } from "@btst/stack/plugins/api";
 
-let seeded = false;
-
 export async function seedFormBuilderData(adapter: Adapter) {
-	if (seeded) return;
-	seeded = true;
-
 	try {
 		const existing = await adapter.findMany({ model: "form", limit: 1 });
 		if (existing.length > 0) return;
diff --git a/demos/form-builder/lib/stack.ts b/demos/form-builder/lib/stack.ts
index 9c12c5b4..74690b13 100644
--- a/demos/form-builder/lib/stack.ts
+++ b/demos/form-builder/lib/stack.ts
@@ -4,8 +4,11 @@ import { formBuilderBackendPlugin } from "@btst/stack/plugins/form-builder/api";
 import { openApiBackendPlugin } from "@btst/stack/plugins/open-api/api";
 import { seedFormBuilderData } from "./seed";
 
+// Persist stack and seed promise on `global` so Next.js module re-evaluations
+// (HMR, per-request server components) don't create a second instance or re-run the seed.
 const globalForStack = global as typeof global & {
 	__btst_stack__?: ReturnType<typeof createStack>;
+	__btst_seeded__?: Promise<void>;
 };
 
 function createStack() {
@@ -25,6 +28,8 @@ function createStack() {
 
 export const myStack = (globalForStack.__btst_stack__ ??= createStack());
 
-seedFormBuilderData(myStack.adapter).catch(console.error);
+globalForStack.__btst_seeded__ ??= seedFormBuilderData(myStack.adapter).catch(
+	console.error,
+);
 
 export const { handler, dbSchema } = myStack;
diff --git a/demos/form-builder/package.json b/demos/form-builder/package.json
index c9bcfe7d..dddcda1d 100644
--- a/demos/form-builder/package.json
+++ b/demos/form-builder/package.json
@@ -3,14 +3,14 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "next dev",
-    "build": "next build",
+    "dev": "node copy-stack-src.mjs && next dev",
+    "build": "node copy-stack-src.mjs && next build",
     "start": "next start"
   },
   "dependencies": {
     "@ai-sdk/react": "^3.0.118",
     "@btst/adapter-memory": "^2.0.3",
-    "@btst/stack": "^2.5.1",
+    "@btst/stack": "^2.5.2",
     "@btst/yar": "^1.2.0",
     "@hookform/resolvers": "^5.2.2",
     "@radix-ui/react-checkbox": "^1.3.3",
@@ -31,7 +31,7 @@
     "highlight.js": "^11.11.1",
     "katex": "^0.16.35",
     "lucide-react": "^0.577.0",
-    "next": "16.1.6",
+    "next": "15.4.1",
     "next-themes": "^0.4.6",
     "radix-ui": "^1.4.3",
     "react": "19.2.3",
diff --git a/demos/kanban/.gitignore b/demos/kanban/.gitignore
index 7fc49260..abb3b440 100644
--- a/demos/kanban/.gitignore
+++ b/demos/kanban/.gitignore
@@ -12,3 +12,5 @@
 # misc
 .DS_Store
 *.pem
+.btst-stack-src/
+.btst-stack-ui/
diff --git a/demos/kanban/app/globals.css b/demos/kanban/app/globals.css
index 05473a81..f0d34577 100644
--- a/demos/kanban/app/globals.css
+++ b/demos/kanban/app/globals.css
@@ -2,6 +2,15 @@
 @import "tw-animate-css";
 @import "@btst/stack/plugins/kanban/css";
 @import "@btst/stack/plugins/route-docs/css";
+/* WebContainers workaround: the WASM Tailwind scanner cannot traverse node_modules
+ * (https://github.com/tailwindlabs/tailwindcss/issues/18418). copy-stack-src.mjs
+ * (run via predev/prebuild) copies @btst/stack/src outside node_modules so Tailwind
+ * can scan it. Safe to remove once the upstream bug is fixed. */
+@source "./.btst-stack-src/**/*.{ts,tsx}";
+@source "./.btst-stack-ui/**/*.{ts,tsx}";
+/* Monorepo fallback: direct source path used in local development */
+@source "../../../packages/stack/src/**/*.{ts,tsx}";
+@source "../../../packages/ui/src/**/*.{ts,tsx}";
 
 @custom-variant dark (&:is(.dark *));
 
diff --git a/demos/kanban/copy-stack-src.mjs b/demos/kanban/copy-stack-src.mjs
new file mode 100644
index 00000000..dc457f07
--- /dev/null
+++ b/demos/kanban/copy-stack-src.mjs
@@ -0,0 +1,45 @@
+#!/usr/bin/env node
+/**
+ * Copies @btst/stack/src outside of node_modules so Tailwind's WASM scanner
+ * (used in WebContainers/StackBlitz) can traverse it.
+ *
+ * The WASM oxide scanner cannot scan inside node_modules due to a bug:
+ * https://github.com/tailwindlabs/tailwindcss/issues/18418
+ *
+ * Run automatically via the predev/prebuild npm lifecycle hooks.
+ */
+import { cp, mkdir, rm } from "fs/promises";
+import { existsSync } from "fs";
+
+const src = "node_modules/@btst/stack/src";
+const dest = ".btst-stack-src";
+
+const uiSrc = "node_modules/@btst/stack/dist/packages/ui";
+const uiDest = ".btst-stack-ui";
+
+if (!existsSync(src)) {
+	// Likely running in the monorepo where the workspace symlink does not expose
+	// src/ — fall back gracefully; @source paths in globals.css cover this case.
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/src not found, skipping",
+	);
+	process.exit(0);
+}
+
+await rm(dest, { recursive: true, force: true });
+await mkdir(dest, { recursive: true });
+await cp(src, dest, { recursive: true });
+console.log("[copy-stack-src] copied @btst/stack/src → .btst-stack-src");
+
+if (existsSync(uiSrc)) {
+	await rm(uiDest, { recursive: true, force: true });
+	await mkdir(uiDest, { recursive: true });
+	await cp(uiSrc, uiDest, { recursive: true });
+	console.log(
+		"[copy-stack-src] copied @btst/stack/dist/packages/ui → .btst-stack-ui",
+	);
+} else {
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/dist/packages/ui not found, skipping",
+	);
+}
diff --git a/demos/kanban/lib/seed.ts b/demos/kanban/lib/seed.ts
index 7342f974..793aa4ea 100644
--- a/demos/kanban/lib/seed.ts
+++ b/demos/kanban/lib/seed.ts
@@ -5,12 +5,7 @@ import {
 } from "@btst/stack/plugins/kanban/api";
 import type { Adapter } from "@btst/stack/plugins/api";
 
-let seeded = false;
-
 export async function seedKanbanData(adapter: Adapter) {
-	if (seeded) return;
-	seeded = true;
-
 	try {
 		const board = await findOrCreateKanbanBoard(
 			adapter,
diff --git a/demos/kanban/lib/stack.ts b/demos/kanban/lib/stack.ts
index 77cd2fee..0afac7d3 100644
--- a/demos/kanban/lib/stack.ts
+++ b/demos/kanban/lib/stack.ts
@@ -4,8 +4,11 @@ import { kanbanBackendPlugin } from "@btst/stack/plugins/kanban/api";
 import { openApiBackendPlugin } from "@btst/stack/plugins/open-api/api";
 import { seedKanbanData } from "./seed";
 
+// Persist stack and seed promise on `global` so Next.js module re-evaluations
+// (HMR, per-request server components) don't create a second instance or re-run the seed.
 const globalForStack = global as typeof global & {
 	__btst_stack__?: ReturnType<typeof createStack>;
+	__btst_seeded__?: Promise<void>;
 };
 
 function createStack() {
@@ -25,6 +28,8 @@ function createStack() {
 
 export const myStack = (globalForStack.__btst_stack__ ??= createStack());
 
-seedKanbanData(myStack.adapter).catch(console.error);
+globalForStack.__btst_seeded__ ??= seedKanbanData(myStack.adapter).catch(
+	console.error,
+);
 
 export const { handler, dbSchema } = myStack;
diff --git a/demos/kanban/package.json b/demos/kanban/package.json
index 26c02bb0..b2cac79c 100644
--- a/demos/kanban/package.json
+++ b/demos/kanban/package.json
@@ -3,14 +3,14 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "next dev",
-    "build": "next build",
+    "dev": "node copy-stack-src.mjs && next dev",
+    "build": "node copy-stack-src.mjs && next build",
     "start": "next start"
   },
   "dependencies": {
     "@ai-sdk/react": "^3.0.118",
     "@btst/adapter-memory": "^2.0.3",
-    "@btst/stack": "^2.5.1",
+    "@btst/stack": "^2.5.2",
     "@btst/yar": "^1.2.0",
     "@dnd-kit/core": "^6.3.1",
     "@dnd-kit/sortable": "^10.0.0",
@@ -30,7 +30,7 @@
     "clsx": "^2.1.1",
     "date-fns": "^4.1.0",
     "lucide-react": "^0.577.0",
-    "next": "16.1.6",
+    "next": "15.4.1",
     "next-themes": "^0.4.6",
     "radix-ui": "^1.4.3",
     "react": "19.2.3",
diff --git a/demos/ui-builder/.gitignore b/demos/ui-builder/.gitignore
index 7fc49260..abb3b440 100644
--- a/demos/ui-builder/.gitignore
+++ b/demos/ui-builder/.gitignore
@@ -12,3 +12,5 @@
 # misc
 .DS_Store
 *.pem
+.btst-stack-src/
+.btst-stack-ui/
diff --git a/demos/ui-builder/app/globals.css b/demos/ui-builder/app/globals.css
index a9d201e4..eaf9e8f4 100644
--- a/demos/ui-builder/app/globals.css
+++ b/demos/ui-builder/app/globals.css
@@ -3,6 +3,15 @@
 @import "@btst/stack/plugins/ui-builder/css";
 @import "@btst/stack/plugins/cms/css";
 @import "@btst/stack/plugins/route-docs/css";
+/* WebContainers workaround: the WASM Tailwind scanner cannot traverse node_modules
+ * (https://github.com/tailwindlabs/tailwindcss/issues/18418). copy-stack-src.mjs
+ * (run via predev/prebuild) copies @btst/stack/src outside node_modules so Tailwind
+ * can scan it. Safe to remove once the upstream bug is fixed. */
+@source "./.btst-stack-src/**/*.{ts,tsx}";
+@source "./.btst-stack-ui/**/*.{ts,tsx}";
+/* Monorepo fallback: direct source path used in local development */
+@source "../../../packages/stack/src/**/*.{ts,tsx}";
+@source "../../../packages/ui/src/**/*.{ts,tsx}";
 
 @custom-variant dark (&:is(.dark *));
 
diff --git a/demos/ui-builder/copy-stack-src.mjs b/demos/ui-builder/copy-stack-src.mjs
new file mode 100644
index 00000000..dc457f07
--- /dev/null
+++ b/demos/ui-builder/copy-stack-src.mjs
@@ -0,0 +1,45 @@
+#!/usr/bin/env node
+/**
+ * Copies @btst/stack/src outside of node_modules so Tailwind's WASM scanner
+ * (used in WebContainers/StackBlitz) can traverse it.
+ *
+ * The WASM oxide scanner cannot scan inside node_modules due to a bug:
+ * https://github.com/tailwindlabs/tailwindcss/issues/18418
+ *
+ * Run automatically via the predev/prebuild npm lifecycle hooks.
+ */
+import { cp, mkdir, rm } from "fs/promises";
+import { existsSync } from "fs";
+
+const src = "node_modules/@btst/stack/src";
+const dest = ".btst-stack-src";
+
+const uiSrc = "node_modules/@btst/stack/dist/packages/ui";
+const uiDest = ".btst-stack-ui";
+
+if (!existsSync(src)) {
+	// Likely running in the monorepo where the workspace symlink does not expose
+	// src/ — fall back gracefully; @source paths in globals.css cover this case.
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/src not found, skipping",
+	);
+	process.exit(0);
+}
+
+await rm(dest, { recursive: true, force: true });
+await mkdir(dest, { recursive: true });
+await cp(src, dest, { recursive: true });
+console.log("[copy-stack-src] copied @btst/stack/src → .btst-stack-src");
+
+if (existsSync(uiSrc)) {
+	await rm(uiDest, { recursive: true, force: true });
+	await mkdir(uiDest, { recursive: true });
+	await cp(uiSrc, uiDest, { recursive: true });
+	console.log(
+		"[copy-stack-src] copied @btst/stack/dist/packages/ui → .btst-stack-ui",
+	);
+} else {
+	console.log(
+		"[copy-stack-src] node_modules/@btst/stack/dist/packages/ui not found, skipping",
+	);
+}
diff --git a/demos/ui-builder/lib/seed.ts b/demos/ui-builder/lib/seed.ts
index d8461d25..039329e2 100644
--- a/demos/ui-builder/lib/seed.ts
+++ b/demos/ui-builder/lib/seed.ts
@@ -1,11 +1,6 @@
 import { UI_BUILDER_TYPE_SLUG } from "@btst/stack/plugins/ui-builder";
 
-let seeded = false;
-
 export async function seedUIBuilderData(api: any) {
-	if (seeded) return;
-	seeded = true;
-
 	try {
 		// This also calls ensureSynced internally
 		const existing = await api.cms.getAllContentItems(UI_BUILDER_TYPE_SLUG, {
diff --git a/demos/ui-builder/lib/stack.ts b/demos/ui-builder/lib/stack.ts
index c2664e89..36ca5eaf 100644
--- a/demos/ui-builder/lib/stack.ts
+++ b/demos/ui-builder/lib/stack.ts
@@ -5,8 +5,11 @@ import { openApiBackendPlugin } from "@btst/stack/plugins/open-api/api";
 import { UI_BUILDER_CONTENT_TYPE } from "@btst/stack/plugins/ui-builder";
 import { seedUIBuilderData } from "./seed";
 
+// Persist stack and seed promise on `global` so Next.js module re-evaluations
+// (HMR, per-request server components) don't create a second instance or re-run the seed.
 const globalForStack = global as typeof global & {
 	__btst_stack__?: ReturnType<typeof createStack>;
+	__btst_seeded__?: Promise<void>;
 };
 
 function createStack() {
@@ -28,6 +31,8 @@ function createStack() {
 
 export const myStack = (globalForStack.__btst_stack__ ??= createStack());
 
-seedUIBuilderData(myStack.api).catch(console.error);
+globalForStack.__btst_seeded__ ??= seedUIBuilderData(myStack.api).catch(
+	console.error,
+);
 
 export const { handler, dbSchema } = myStack;
diff --git a/demos/ui-builder/package.json b/demos/ui-builder/package.json
index 23162df6..ca8d856b 100644
--- a/demos/ui-builder/package.json
+++ b/demos/ui-builder/package.json
@@ -3,14 +3,14 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "next dev",
-    "build": "next build",
+    "dev": "node copy-stack-src.mjs && next dev",
+    "build": "node copy-stack-src.mjs && next build",
     "start": "next start"
   },
   "dependencies": {
     "@ai-sdk/react": "^3.0.118",
     "@btst/adapter-memory": "^2.0.3",
-    "@btst/stack": "^2.5.1",
+    "@btst/stack": "^2.5.2",
     "@btst/yar": "^1.2.0",
     "@dnd-kit/core": "^6.3.1",
     "@dnd-kit/sortable": "^10.0.0",
@@ -46,7 +46,7 @@
     "clsx": "^2.1.1",
     "date-fns": "^4.1.0",
     "lucide-react": "^0.577.0",
-    "next": "16.1.6",
+    "next": "15.4.1",
     "next-themes": "^0.4.6",
     "radix-ui": "^1.4.3",
     "react": "19.2.3",
diff --git a/docs/content/docs/demos/ai-chat.mdx b/docs/content/docs/demos/ai-chat.mdx
index a22efc91..c74ddb8d 100644
--- a/docs/content/docs/demos/ai-chat.mdx
+++ b/docs/content/docs/demos/ai-chat.mdx
@@ -15,4 +15,11 @@ A standalone Next.js demo showcasing the `ai-chat` plugin in **public mode** (no
 To enable AI responses in StackBlitz, add your `OPENAI_API_KEY` to the `.env.local` file (copy from `.env.local.example`).
 </Callout>
 
-[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/ai-chat)
+[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/ai-chat?file=%2Flib%2Fstack.ts)
+[Open in StackBlitz →](https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/ai-chat?startScript=dev&file=lib%2Fstack.ts)
+
+<iframe
+  src="https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/ai-chat?startScript=dev&embed=1&file=lib%2Fstack.ts&view=preview&initialPath=%2Fpages%2Fchat"
+  style={{width:"100%", height:"600px", border:"0", borderRadius:"4px"}}
+  title="BTST AI Chat Demo"
+/>
diff --git a/docs/content/docs/demos/blog.mdx b/docs/content/docs/demos/blog.mdx
index eb19a124..70bb805f 100644
--- a/docs/content/docs/demos/blog.mdx
+++ b/docs/content/docs/demos/blog.mdx
@@ -12,4 +12,11 @@ A standalone Next.js demo showcasing the `blog` plugin. Three sample posts are s
 - API Docs at `/api/data/reference` (OpenAPI Scalar)
 - Route Docs at `/pages/route-docs`
 
-[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/blog)
+[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/blog?file=%2Flib%2Fstack.ts)
+[Open in StackBlitz →](https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/blog?startScript=dev&file=lib%2Fstack.ts)
+
+<iframe
+  src="https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/blog?startScript=dev&embed=1&file=lib%2Fstack.ts&view=preview&initialPath=%2Fpages%2Fblog"
+  style={{width:"100%", height:"600px", border:"0", borderRadius:"4px"}}
+  title="BTST Blog Demo"
+/>
diff --git a/docs/content/docs/demos/cms.mdx b/docs/content/docs/demos/cms.mdx
index bdf09aec..7e20e53e 100644
--- a/docs/content/docs/demos/cms.mdx
+++ b/docs/content/docs/demos/cms.mdx
@@ -11,4 +11,11 @@ A standalone Next.js demo showcasing the `cms` plugin. An `Article` content type
 - API Docs at `/api/data/reference` (OpenAPI Scalar)
 - Route Docs at `/pages/route-docs`
 
-[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/cms)
+[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/cms?file=%2Flib%2Fstack.ts)
+[Open in StackBlitz →](https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/cms?startScript=dev&file=lib%2Fstack.ts)
+
+<iframe
+  src="https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/cms?startScript=dev&embed=1&file=lib%2Fstack.ts&view=preview&initialPath=%2Fpages%2Fcms"
+  style={{width:"100%", height:"600px", border:"0", borderRadius:"4px"}}
+  title="BTST CMS Demo"
+/>
diff --git a/docs/content/docs/demos/form-builder.mdx b/docs/content/docs/demos/form-builder.mdx
index c1ea7b24..b1f73ea6 100644
--- a/docs/content/docs/demos/form-builder.mdx
+++ b/docs/content/docs/demos/form-builder.mdx
@@ -13,4 +13,11 @@ A standalone Next.js demo showcasing the `form-builder` plugin. Two sample forms
 - API Docs at `/api/data/reference` (OpenAPI Scalar)
 - Route Docs at `/pages/route-docs`
 
-[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/form-builder)
+[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/form-builder?file=%2Flib%2Fstack.ts)
+[Open in StackBlitz →](https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/form-builder?startScript=dev&file=lib%2Fstack.ts)
+
+<iframe
+  src="https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/form-builder?startScript=dev&embed=1&file=lib%2Fstack.ts&view=preview&initialPath=%2Fpages%2Fform-builder"
+  style={{width:"100%", height:"600px", border:"0", borderRadius:"4px"}}
+  title="BTST Form Builder Demo"
+/>
diff --git a/docs/content/docs/demos/kanban.mdx b/docs/content/docs/demos/kanban.mdx
index 8302dfd9..74342d28 100644
--- a/docs/content/docs/demos/kanban.mdx
+++ b/docs/content/docs/demos/kanban.mdx
@@ -12,4 +12,11 @@ A standalone Next.js demo showcasing the `kanban` plugin. One demo board with 4
 - API Docs at `/api/data/reference` (OpenAPI Scalar)
 - Route Docs at `/pages/route-docs`
 
-[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/kanban)
+[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/kanban?file=%2Flib%2Fstack.ts)
+[Open in StackBlitz →](https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/kanban?startScript=dev&file=lib%2Fstack.ts)
+
+<iframe
+  src="https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/kanban?startScript=dev&embed=1&file=lib%2Fstack.ts&view=preview&initialPath=%2Fpages%2Fkanban"
+  style={{width:"100%", height:"600px", border:"0", borderRadius:"4px"}}
+  title="BTST Kanban Demo"
+/>
diff --git a/docs/content/docs/demos/ui-builder.mdx b/docs/content/docs/demos/ui-builder.mdx
index e4f4d5bb..b59a0625 100644
--- a/docs/content/docs/demos/ui-builder.mdx
+++ b/docs/content/docs/demos/ui-builder.mdx
@@ -12,4 +12,11 @@ A standalone Next.js demo showcasing the `ui-builder` plugin backed by the `cms`
 - API Docs at `/api/data/reference` (OpenAPI Scalar)
 - Route Docs at `/pages/route-docs`
 
-[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/ui-builder)
+[Open in CodeSandbox →](https://codesandbox.io/p/devbox/github/better-stack-ai/better-stack/tree/main/demos/ui-builder?file=%2Flib%2Fstack.ts)
+[Open in StackBlitz →](https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/ui-builder?startScript=dev&file=lib%2Fstack.ts)
+
+<iframe
+  src="https://stackblitz.com/github/better-stack-ai/better-stack/tree/main/demos/ui-builder?startScript=dev&embed=1&file=lib%2Fstack.ts&view=preview&initialPath=%2Fpages%2Fui-builder"
+  style={{width:"100%", height:"600px", border:"0", borderRadius:"4px"}}
+  title="BTST UI Builder Demo"
+/>
diff --git a/packages/stack/package.json b/packages/stack/package.json
index ddaa8297..749c22ca 100644
--- a/packages/stack/package.json
+++ b/packages/stack/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@btst/stack",
-  "version": "2.5.1",
+  "version": "2.5.2",
   "description": "A composable, plugin-based library for building full-stack applications.",
   "repository": {
     "type": "git",
diff --git a/packages/stack/scripts/postbuild.cjs b/packages/stack/scripts/postbuild.cjs
index 636961ce..e9e054fc 100644
--- a/packages/stack/scripts/postbuild.cjs
+++ b/packages/stack/scripts/postbuild.cjs
@@ -2,6 +2,9 @@
 /*
   Post-build step for BTST package.
   - Copies all .css files from src/plugins/** to dist/plugins/** preserving structure
+  - Resolves @workspace/ui/... CSS imports in dist files by inlining the referenced
+    content into dist/plugins/shared/ and rewriting the import path — so consumers
+    outside the monorepo (e.g. npm installs, StackBlitz) never see workspace imports
   - Executes optional per-plugin postbuild scripts if present at:
     src/plugins/<plugin>/postbuild.(js|cjs|mjs)
 */
@@ -54,6 +57,118 @@ function copyAllPluginCss() {
 	}
 }
 
+/**
+ * Recursively inline relative @import statements in a CSS file, producing a
+ * single blob of CSS with no relative imports left. Non-relative imports
+ * (e.g. "tailwindcss", bare package names) are kept as-is.
+ */
+function inlineCssImports(cssContent, baseDir, seen = new Set()) {
+	return cssContent.replace(
+		/^@import\s+"([^"]+)";?[ \t]*$/gm,
+		(match, importPath) => {
+			if (!importPath.startsWith("./") && !importPath.startsWith("../")) {
+				return match;
+			}
+			const resolved = path.resolve(baseDir, importPath);
+			if (seen.has(resolved)) return "";
+			if (!fs.existsSync(resolved)) return match;
+			seen.add(resolved);
+			const content = fs.readFileSync(resolved, "utf8");
+			return inlineCssImports(content, path.dirname(resolved), seen);
+		},
+	);
+}
+
+/**
+ * After all plugin CSS files are copied to dist, scan them for
+ * @import "@workspace/ui/..." declarations. For each unique specifier found:
+ *   1. Resolve the actual file via packages/ui/package.json exports map
+ *   2. Inline all relative sub-imports recursively into one blob
+ *   3. Write the blob to dist/plugins/shared/<slug>.css
+ *   4. Rewrite the @workspace/ui/... import in the dist CSS to the relative path
+ *
+ * This keeps source files using proper workspace imports while ensuring the
+ * published package is self-contained.
+ */
+function resolveWorkspaceCssImports() {
+	const UI_PKG_DIR = path.resolve(ROOT, "..", "ui");
+	const UI_PKG_JSON = path.join(UI_PKG_DIR, "package.json");
+	if (!fs.existsSync(UI_PKG_JSON)) {
+		console.warn(
+			"@btst/stack: packages/ui not found — skipping workspace CSS resolution",
+		);
+		return;
+	}
+
+	const uiExports =
+		JSON.parse(fs.readFileSync(UI_PKG_JSON, "utf8")).exports || {};
+
+	function resolveUiSpecifier(specifier) {
+		// "@workspace/ui/components/foo/bar.css" → "./components/foo/bar.css"
+		const subpath = specifier.replace("@workspace/ui", ".");
+		const exportEntry = uiExports[subpath];
+		if (!exportEntry) return null;
+		return path.resolve(UI_PKG_DIR, exportEntry);
+	}
+
+	const WORKSPACE_IMPORT_RE = /@import\s+"(@workspace\/ui[^"]+)";?[ \t]*/g;
+	const sharedDir = path.join(DIST_PLUGINS_DIR, "shared");
+
+	// specifier → filename written in dist/plugins/shared/
+	const generated = new Map();
+
+	if (!fs.existsSync(DIST_PLUGINS_DIR)) return;
+
+	for (const filePath of walk(DIST_PLUGINS_DIR)) {
+		if (!filePath.endsWith(".css")) continue;
+
+		let content = fs.readFileSync(filePath, "utf8");
+		if (!WORKSPACE_IMPORT_RE.test(content)) continue;
+		WORKSPACE_IMPORT_RE.lastIndex = 0;
+
+		let modified = false;
+
+		content = content.replace(WORKSPACE_IMPORT_RE, (match, specifier) => {
+			if (!generated.has(specifier)) {
+				const resolvedPath = resolveUiSpecifier(specifier);
+				if (!resolvedPath || !fs.existsSync(resolvedPath)) {
+					console.warn(
+						`@btst/stack: could not resolve workspace import: ${specifier}`,
+					);
+					return match;
+				}
+				const raw = fs.readFileSync(resolvedPath, "utf8");
+				const inlined = inlineCssImports(raw, path.dirname(resolvedPath));
+				// Derive a stable filename from the specifier
+				const slug = specifier
+					.replace("@workspace/ui/", "")
+					.replace(/\//g, "-");
+				ensureDir(sharedDir);
+				const destPath = path.join(sharedDir, slug);
+				fs.writeFileSync(destPath, inlined);
+				generated.set(specifier, slug);
+				console.log(
+					`@btst/stack: resolved workspace import "${specifier}" → shared/${slug}`,
+				);
+			}
+			const slug = generated.get(specifier);
+			const rel = path
+				.relative(path.dirname(filePath), path.join(sharedDir, slug))
+				.replace(/\\/g, "/");
+			const relNormalized = rel.startsWith(".") ? rel : `./${rel}`;
+			modified = true;
+			return `@import "${relNormalized}";`;
+		});
+
+		if (modified) {
+			fs.writeFileSync(filePath, content);
+			console.log(
+				`@btst/stack: rewrote workspace imports in ${path.relative(DIST_PLUGINS_DIR, filePath)}`,
+			);
+		}
+	}
+}
+
 function runPerPluginPostbuilds() {
 	if (!fs.existsSync(SRC_PLUGINS_DIR)) return;
 	const candidates = ["postbuild.js", "postbuild.cjs", "postbuild.mjs"];
@@ -93,6 +208,7 @@ function runPerPluginPostbuilds() {
 function main() {
 	ensureDir(DIST_PLUGINS_DIR);
 	copyAllPluginCss();
+	resolveWorkspaceCssImports();
 	runPerPluginPostbuilds();
 }