diff --git a/hatch_build.py b/hatch_build.py
index 0f4e9d5..1924711 100644
--- a/hatch_build.py
+++ b/hatch_build.py
@@ -47,8 +47,24 @@ def initialize(self, version: str, build_data: dict) -> None:  # noqa: ARG002
                 f"The wheel needs the built {' and '.join(missing)} under share/, and npm is not "
                 "on PATH to build them. Run `make build` first, or set DATALAYER_DECKS_SKIP_JS=1."
             )
-        if not (ROOT / "node_modules").is_dir() and not (ROOT.parent.parent.parent / "node_modules").is_dir():
+        workspace = ROOT.parent.parent.parent / "node_modules"
+        if not (ROOT / "node_modules").is_dir() and not workspace.is_dir():
             subprocess.run([npm, "install"], cwd=ROOT, check=True)
+        # The interface (app/) is a package of its own, never a workspace
+        # member: nothing hoists its dependencies, and its bundler has to be
+        # its own -- after a `git clean`, app/ otherwise resolves whatever
+        # rsbuild the workspace hoisted, which is not the one it was written
+        # against. The plugin is a workspace member when there is a workspace
+        # (hoisted, nothing to install: `npm install` inside a member would
+        # redirect to the whole workspace) and a package of its own in a plain
+        # checkout, where CI installs it too.
+        own = [ROOT / "app"]
+        if not workspace.is_dir():
+            own.append(ROOT / "plugins" / "ai-agents")
+        for package in own:
+            if not (package / "node_modules").is_dir():
+                self.app.display_info(f"Installing {package.relative_to(ROOT)}'s dependencies ...")
+                subprocess.run([npm, "install", "--no-audit", "--no-fund"], cwd=package, check=True)
         self.app.display_info(f"Building the {' and '.join(missing)} into share/ ...")
         subprocess.run([npm, "run", "build:all"], cwd=ROOT, check=True)
         for name, marker in (("interface", APP), ("container", CONTAINER)):