diff --git a/README.md b/README.md
index 04ba52f..8595bab 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ no network: plain Python over the tracked files.
 | `docref` | the repos' own trees | ``<repo> `FILE.md` `` naming a file that does not exist; relative markdown links that do not resolve |
 | `binaries` | each repo's `Cargo.toml` and `deploy/*.service` | project-yukart `REPOS.md` missing a deployed binary; `ORIN-RUNTIME.md` missing a deployed service |
 | `frontmatter` | the docs convention | a `docs/**/*.md` without front matter, or with an unknown `type` |
+| `copy` | contracts | a file under `assets/contracts/<path>` that is not byte-identical to contracts' `<path>` (or has no source there) |
 
 ## Run it
 
diff --git a/crosscheck.py b/crosscheck.py
index b61ef76..daef056 100644
--- a/crosscheck.py
+++ b/crosscheck.py
@@ -19,6 +19,8 @@ Exit status 1 when anything is found. Checks, and the source each one trusts:
   binaries   REPOS.md's row for a repo names every deployed [[bin]] in its Cargo.toml;
              ORIN-RUNTIME.md names every service a repo deploys
   frontmatter  every docs/**/*.md starts with front matter whose type is known
+  copy       a file under assets/contracts/<path> in any repo is byte-identical to
+             contracts' <path> (bundled copies, e.g. the app's checklists)
 """
 
 import json
@@ -246,6 +248,21 @@ def check_frontmatter(ws: Workspace) -> None:
             find(f"{repo}/{rel}", 1, "frontmatter", f"type '{t.group(1)}' is not one of {sorted(DOC_TYPES)}")
 
 
+# ── bundled copies of contracts files ────────────────────────────────────────
+
+
+def check_copies(ws: Workspace) -> None:
+    for repo in ws.repos:
+        for rel in ws.files[repo]:
+            if not rel.startswith("assets/contracts/"):
+                continue
+            src = rel.removeprefix("assets/contracts/")
+            if src not in ws.files["contracts"]:
+                find(f"{repo}/{rel}", 1, "copy", f"contracts has no {src} to copy")
+            elif (ws.root / repo / rel).read_bytes() != (ws.root / "contracts" / src).read_bytes():
+                find(f"{repo}/{rel}", 1, "copy", f"differs from contracts {src}; run tool/sync-contracts.sh")
+
+
 def main() -> int:
     root = Path(sys.argv[1] if len(sys.argv) > 1 else ".").resolve()
     ws = Workspace(root)
@@ -253,7 +270,7 @@ def main() -> int:
     if missing:
         print(f"crosscheck: {root} lacks {', '.join(sorted(missing))}; nothing to check against", file=sys.stderr)
         return 2
-    for check in (check_decisions, check_topics, check_docrefs, check_binaries, check_frontmatter):
+    for check in (check_decisions, check_topics, check_docrefs, check_binaries, check_frontmatter, check_copies):
         check(ws)
     for f in findings:
         print(f)