move registry into own files

tests/test_registry.py

@@ -0,0 +1,30 @@
+import json
+
+from browser_cli.registry import load_registry, save_registry, update_registry
+
+
+def test_load_registry_tolerates_trailing_garbage_from_old_non_atomic_writes(tmp_path):
+    registry = tmp_path / "registry.json"
+    registry.write_text('{"main": "/tmp/.browser_cli/main.sock"}"}', encoding="utf-8")
+
+    assert load_registry(registry) == {"main": "/tmp/.browser_cli/main.sock"}
+
+
+def test_update_registry_repairs_corrupted_registry_and_preserves_entries(tmp_path):
+    registry = tmp_path / "registry.json"
+    registry.write_text('{"main": "/tmp/.browser_cli/main.sock"}"}', encoding="utf-8")
+
+    update_registry("work", "/tmp/.browser_cli/work.sock", registry)
+
+    assert json.loads(registry.read_text(encoding="utf-8")) == {
+        "main": "/tmp/.browser_cli/main.sock",
+        "work": "/tmp/.browser_cli/work.sock",
+    }
+
+
+def test_save_registry_writes_valid_json_atomically(tmp_path):
+    registry = tmp_path / "registry.json"
+
+    save_registry({"main": "/tmp/main.sock"}, registry)
+
+    assert json.loads(registry.read_text(encoding="utf-8")) == {"main": "/tmp/main.sock"}