diff --git a/packages/sdk/src/index.ts b/packages/sdk/src/index.ts
index 57ef673c7..682b217bc 100644
--- a/packages/sdk/src/index.ts
+++ b/packages/sdk/src/index.ts
@@ -33,10 +33,8 @@ export type { PersistQueueModule, PersistQueueOptions } from "./persist-queue.js
 
 export type { PersistAdapter, PreviewAdapter, PersistVersionEntry } from "./adapters/types.js";
 
-// Concrete adapter factories.
+// Concrete adapter factories (browser-safe — Node-only fs adapter: @hyperframes/sdk/adapters/fs).
 export { createMemoryAdapter } from "./adapters/memory.js";
 export { createHeadlessAdapter } from "./adapters/headless.js";
-export { createFsAdapter } from "./adapters/fs.js";
-export type { FsAdapterOptions } from "./adapters/fs.js";
 export { createHttpAdapter } from "./adapters/http.js";
 export type { HttpAdapterOptions } from "./adapters/http.js";
diff --git a/packages/studio/package.json b/packages/studio/package.json
index 7173b9a7f..125cb31ca 100644
--- a/packages/studio/package.json
+++ b/packages/studio/package.json
@@ -38,6 +38,7 @@
     "@codemirror/view": "6.40.0",
     "@hyperframes/core": "workspace:*",
     "@hyperframes/player": "workspace:*",
+    "@hyperframes/sdk": "workspace:*",
     "@phosphor-icons/react": "^2.1.10",
     "mediabunny": "^1.45.3"
   },
diff --git a/packages/studio/src/App.tsx b/packages/studio/src/App.tsx
index 2f944b228..b884e726b 100644
--- a/packages/studio/src/App.tsx
+++ b/packages/studio/src/App.tsx
@@ -12,6 +12,8 @@ import { usePreviewPersistence } from "./hooks/usePreviewPersistence";
 import { useTimelineEditing } from "./hooks/useTimelineEditing";
 import type { BlockPreviewInfo } from "./components/sidebar/BlocksTab";
 import { useDomEditSession } from "./hooks/useDomEditSession";
+import { useSdkSession } from "./hooks/useSdkSession";
+import { useSdkSelectionSync } from "./hooks/useSdkSelectionSync";
 import { useBlockHandlers } from "./hooks/useBlockHandlers";
 import { useAppHotkeys } from "./hooks/useAppHotkeys";
 import { useClipboard } from "./hooks/useClipboard";
@@ -145,6 +147,8 @@ export function StudioApp() {
     setRefreshKey,
   });
 
+  const sdkSession = useSdkSession(projectId, activeCompPath);
+
   useEffect(() => {
     if (activeCompPathHydrated) return;
     if (!fileManager.fileTreeLoaded) return;
@@ -314,6 +318,12 @@ export function StudioApp() {
       if (Number.isFinite(p)) domEditSession.handleGsapRemoveKeyframe(a.id, p);
     });
   };
+  useSdkSelectionSync(
+    sdkSession,
+    domEditSession.domEditSelection,
+    domEditSession.domEditGroupSelections,
+  );
+
   useCaptionDetection({
     projectId,
     activeCompPath,
diff --git a/packages/studio/src/hooks/useSdkSelectionSync.ts b/packages/studio/src/hooks/useSdkSelectionSync.ts
new file mode 100644
index 000000000..d36cfdabe
--- /dev/null
+++ b/packages/studio/src/hooks/useSdkSelectionSync.ts
@@ -0,0 +1,25 @@
+import { useEffect } from "react";
+import type { Composition } from "@hyperframes/sdk";
+import type { DomEditSelection } from "../components/editor/domEditing";
+
+function toHfIds(group: DomEditSelection[], primary: DomEditSelection | null): string[] {
+  const source = group.length > 0 ? group : primary ? [primary] : [];
+  return source.flatMap((s) => (s.hfId ? [s.hfId] : []));
+}
+
+/**
+ * Stage 7 Step 2 — mirrors Studio canvas selection into the SDK session.
+ *
+ * Calls session.setSelection(hfIds) whenever domEditSelection or
+ * domEditGroupSelections changes. Pure effect; no existing hook modified.
+ */
+export function useSdkSelectionSync(
+  session: Composition | null,
+  domEditSelection: DomEditSelection | null,
+  domEditGroupSelections: DomEditSelection[],
+): void {
+  useEffect(() => {
+    if (!session) return;
+    session.setSelection(toHfIds(domEditGroupSelections, domEditSelection));
+  }, [session, domEditSelection, domEditGroupSelections]);
+}
diff --git a/packages/studio/src/hooks/useSdkSession.ts b/packages/studio/src/hooks/useSdkSession.ts
new file mode 100644
index 000000000..e9cf7256d
--- /dev/null
+++ b/packages/studio/src/hooks/useSdkSession.ts
@@ -0,0 +1,53 @@
+import { useState, useEffect } from "react";
+import { openComposition } from "@hyperframes/sdk";
+import { createHttpAdapter } from "@hyperframes/sdk/adapters/http";
+import type { Composition } from "@hyperframes/sdk";
+
+/**
+ * Stage 7 Step 1 — SDK session wired to the active composition.
+ *
+ * Creates an SDK Composition backed by createHttpAdapter on every
+ * (projectId, activeCompPath) change, disposes the old one on cleanup.
+ * The session is idle until Step 3 routes dispatch ops through it.
+ */
+export function useSdkSession(
+  projectId: string | null,
+  activeCompPath: string | null,
+): Composition | null {
+  const [session, setSession] = useState<Composition | null>(null);
+
+  useEffect(() => {
+    if (!projectId || !activeCompPath) {
+      setSession(null);
+      return;
+    }
+
+    let cancelled = false;
+    let comp: Composition | null = null;
+
+    const url = `/api/projects/${projectId}/files/${encodeURIComponent(activeCompPath)}?optional=1`;
+    fetch(url)
+      .then((r) => r.json())
+      .then(async (data: { content?: string }) => {
+        if (cancelled || typeof data.content !== "string") return;
+        const adapter = createHttpAdapter({
+          projectFilesUrl: `/api/projects/${projectId}`,
+        });
+        comp = await openComposition(data.content, { persist: adapter });
+        comp.on("persist:error", (e) => {
+          console.warn("[sdk] persist:error", e.error);
+        });
+        if (!cancelled) setSession(comp);
+      })
+      .catch(() => {
+        if (!cancelled) setSession(null);
+      });
+
+    return () => {
+      cancelled = true;
+      comp?.dispose();
+    };
+  }, [projectId, activeCompPath]);
+
+  return session;
+}