diff --git a/scripts/CLAUDE.md b/scripts/CLAUDE.md
index 399a5fb5..4db3be64 100644
--- a/scripts/CLAUDE.md
+++ b/scripts/CLAUDE.md
@@ -62,10 +62,11 @@ imports it, except `mcp-app`, which no widget imports and which lands in
 `skills/leaf/mcp-app/` for an MCP host to read from the install.
 
 A bundle reproduces its tracked bytes exactly when every input it fetches is pinned,
-which holds for `marked`, `sortable`, `beautiful-mermaid`, `highlight`, and `jsdiff`,
-so a clean `git status` after a run is the check that the bundle still matches the
-script. `plot` and `pierre` reach npm's resolver for transitive dependencies and inherit
-its ranges, so a diff from either can be an upstream patch rather than drift.
+which holds for `marked`, `sortable`, `beautiful-mermaid`, `floating-ui`, `highlight`,
+and `jsdiff`, so a clean `git status` after a run is the check that the bundle still
+matches the script. `plot`, `pierre`, and `mcp-app` reach npm's resolver for transitive
+dependencies and inherit its ranges, so a diff from one of those can be an upstream
+patch rather than drift.
 
 Rerun a bundle after changing its pin or the registry input it reads; do not patch a
 generated bundle or `examples/corpus.html` directly.
diff --git a/tests/test_interact_layer.py b/tests/test_interact_layer.py
index f403e1bd..5facdaa9 100644
--- a/tests/test_interact_layer.py
+++ b/tests/test_interact_layer.py
@@ -1,5 +1,6 @@
 """CLI, plugin payload, layer, and customization tests."""
 
+import ast
 import contextlib
 import json
 import os
@@ -299,6 +300,51 @@ def names(scope):
     assert not unnamed, f"unnamed in scripts/CLAUDE.md: {unnamed}"
 
 
+def test_the_tooling_instructions_place_every_vendored_bundle():
+    """Whether a rebuild reproduces its bytes must be named where sessions read.
+
+    `scripts/CLAUDE.md` says a clean `git status` after `vendor.py <bundle>` is the
+    check that the bundle still matches the script, and that the check holds only for
+    the bundles whose every fetched input is pinned. That sentence is what a session
+    consults before reading a rebuild's diff as drift or as an upstream patch, so a
+    bundle it never places has no answer either way — which is how `floating-ui`, whose
+    pins cover its whole closure, and `mcp-app`, whose do not, both went unplaced. The
+    names come from `vendor.py` rather than a list here, for the reason the routing
+    above states: a list is the second copy, and the bundle added without the sentence
+    would stay green.
+    """
+    tree = ast.parse((ROOT / "scripts" / "vendor.py").read_text(encoding="utf-8"))
+    bundles = {
+        key.value
+        for node in ast.walk(tree)
+        for target in (
+            node.targets
+            if isinstance(node, ast.Assign)
+            else [node.target]
+            if isinstance(node, ast.AnnAssign)
+            else []
+        )
+        if isinstance(target, ast.Name) and target.id in {"BUILDS", "COPIES"}
+        for key in node.value.keys
+        if isinstance(key, ast.Constant)
+    }
+    paragraphs = [
+        paragraph
+        for paragraph in (ROOT / "scripts" / "CLAUDE.md")
+        .read_text(encoding="utf-8")
+        .split("\n\n")
+        if paragraph.startswith("A bundle reproduces its tracked bytes exactly")
+    ]
+
+    assert bundles, "no bundles read — an empty set places itself"
+    assert len(paragraphs) == 1, (
+        "scripts/CLAUDE.md no longer opens one paragraph with "
+        f"'A bundle reproduces its tracked bytes exactly': {len(paragraphs)} found"
+    )
+    unplaced = sorted(name for name in bundles if f"`{name}`" not in paragraphs[0])
+    assert not unplaced, f"unplaced in scripts/CLAUDE.md: {unplaced}"
+
+
 def test_the_root_instructions_name_every_directory_ci_gates_on_its_own():
     """A gate `uv run pytest tests` does not reach must be named where sessions read.