diff --git a/.gitignore b/.gitignore
index 10477d4..022d93b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -58,3 +58,7 @@ backend/openzaak/seeded.env
 
 # WP-55: render-prod-secrets.sh's output — the real client secret, never committed
 backend/openzaak/setup_configuration/data.prod.yaml
+
+# Agent git worktrees (Claude Code `isolation: "worktree"`) — full checkouts of
+# this repo nested inside it; never commit one.
+.claude/worktrees/
diff --git a/.prettierignore b/.prettierignore
index 2e7e30e..07cb7ce 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -4,6 +4,11 @@ storybook-static*/
 coverage/
 .angular/
 
+# Agent git worktrees — full checkouts of this repo nested inside it, so an
+# unignored `prettier --check .` walks into every one of them (and reports the
+# vendored CIBG files that the top-level ignore already excludes).
+.claude/worktrees/
+
 # Lockfile
 package-lock.json