diff --git a/.claude/scripts/block-node.ts b/.claude/scripts/block-node.ts
new file mode 100644
index 000000000..4de815317
--- /dev/null
+++ b/.claude/scripts/block-node.ts
@@ -0,0 +1,28 @@
+#!/usr/bin/env -S deno run --allow-read
+/**
+ * .claude/scripts/block-node.ts
+ *
+ * Claude Code Pre-Tool hook.
+ * - Blocks shell commands that invoke npm, npx, yarn, pnpm, or node.
+ * - Prints a Deno-friendly reminder to stderr.
+ * - Exits 2 so Claude blocks the tool call and shows the message.
+ */
+
+const rawInput = await new Response(Deno.stdin.readable).text();
+
+let cmd = "";
+try {
+  const payload = JSON.parse(rawInput);
+  cmd = payload?.tool_input?.command ?? "";
+} catch {
+  // If the JSON is malformed we allow the call rather than choke the hook.
+}
+
+if (/\b(npm|npx|yarn|pnpm|node)\b/.test(cmd)) {
+  console.error(
+    "We use **Deno** in this repo – please rewrite the command accordingly.",
+  );
+  Deno.exit(2); // Claude interprets exit-code 2 as “block & surface stderr”
+}
+
+Deno.exit(0); // Let the tool call proceed
diff --git a/.claude/settings.json b/.claude/settings.json
new file mode 100644
index 000000000..7a1a63b02
--- /dev/null
+++ b/.claude/settings.json
@@ -0,0 +1,26 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(grep:*)",
+      "Bash(deno test:*)",
+      "Bash(deno task test:*)",
+      "Bash(find:*)",
+      "Bash(deno lint:*)",
+      "Bash(rg:*)"
+    ],
+    "deny": []
+  },
+  "hooks": {
+    "PreToolUse": [
+      {
+        "matcher": "Bash",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "deno run \"$(git rev-parse --show-toplevel)/.claude/scripts/block-node.ts\""
+          }
+        ]
+      }
+    ]
+  }
+}
diff --git a/.gitignore b/.gitignore
index 2462c1755..5702b4fcb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,3 +16,4 @@ packages/seeder/results
 .claude-prompt.tmp
 .pr-desc.tmp
 dist/
+.claude/settings.local.json