[py] generate the internal BiDi protocol layer from the shared binding-neutral schema

py/BUILD.bazel

@@ -532,6 +532,7 @@ py_library(
     visibility = ["//visibility:public"],
     deps = [
         ":bidi",
+        ":bidi_protocol",
         ":chrome",
         ":chromium",
         ":common",
@@ -561,6 +562,7 @@ py_package(
         "py.selenium",
         "py.selenium.common",
         "py.selenium.webdriver",
+        "py.selenium.webdriver._bidi",
         "py.selenium.webdriver.chrome",
         "py.selenium.webdriver.chromium",
         "py.selenium.webdriver.common",
@@ -748,6 +750,27 @@ generate_bidi(
     spec_version = "1.0",
 )
 
+# Schema-driven BiDi protocol layer (ADR 17701): generated from the shared BiDi
+# schema into the internal `selenium/webdriver/_bidi/` package. The files are
+# checked in here only so the generated output's shape is reviewable; the final
+# PR will generate them at build time rather than commit them.
+py_binary(
+    name = "generate-bidi-protocol",
+    srcs = ["generate_bidi_protocol.py"],
+    args = ["$(location //javascript/selenium-webdriver:create-bidi-src_schema)"],
+    data = ["//javascript/selenium-webdriver:create-bidi-src_schema"],
+    main = "generate_bidi_protocol.py",
+    visibility = ["//visibility:public"],
+)
+
+py_library(
+    name = "bidi_protocol",
+    srcs = glob(["selenium/webdriver/_bidi/**/*.py"]),
+    imports = ["."],
+    visibility = ["//visibility:public"],
+    deps = [":exceptions"],
+)
+
 py_test_suite(
     name = "unit",
     size = "small",
@@ -1036,6 +1059,7 @@ FEATURE_SUITE_DEFS = {
         target_compatible_with = BROWSERS[browser]["target_compatible_with"],
         test_suffix = "%s-bidi" % browser,
         deps = [
+            ":bidi_protocol",  # bidi_protocol_tests.py imports the generated _bidi layer directly
             ":common_alert",  # bidi_browsing_context_tests.py calls EC.alert_is_present()
             ":init-tree",
             ":webserver",