codex: remove C parser golden update path from tests

docs/c_parser/c_parser_implementation_checklist.md

@@ -36,7 +36,7 @@ stable.
 ## Progress Snapshot
 
 - Last updated: 2026-05-24
-- Checklist progress: 623/873 checked (71.4%).
+- Checklist progress: 622/872 checked (71.3%).
 - Current parser status: partial C parser with raw directive metadata, top-level
   source splitting, simple declarations/variables/typedefs, prototype-style
   metadata, K&R diagnostics, simple function signatures, and start/end
@@ -406,12 +406,9 @@ Scope:
       header to dependent header.
 - [x] Generate separate one-file project goldens for STB single-file library
       inputs.
-- [x] Support updating all fixtures.
-- [x] Support updating selected fixtures.
-- [x] Add an environment variable update flow, for example
-      `C_PARSER_UPDATE_GOLDENS=1`.
-- [x] Document whether C uses `C_PARSER_UPDATE_GOLDENS` or a generic
-      `X2PY_UPDATE_GOLDENS`.
+- [x] Regenerate all fixtures with the standalone golden script.
+- [x] Regenerate selected fixtures with the standalone golden script.
+- [x] Keep golden regeneration out of the comparison tests.
 - [x] Create a C error golden generator.
 - [x] Store expected error type, message fragments, diagnostic fragments, and
       parser entrypoint metadata.

docs/c_parser/c_parser_reference.md

@@ -572,10 +572,10 @@ relative to `tests/data/c/` by adding either member filename; any matching
 sibling is included automatically. Fatal diagnostic goldens are regenerated
 with
 `python -m tests.parser.c.errors.generate_c_parser_error_goldens`.
-The active fixture tests also honor `C_PARSER_UPDATE_GOLDENS=1`; C does not
-use a generic update environment variable. Until include-expanded parsing is
-implemented, a paired project records the source-to-header include edge but
-parses the `.c` and `.h` members separately.
+The parser goldens are regenerated by the standalone scripts above, not by
+the comparison tests. Until include-expanded parsing is implemented, a paired
+project records the source-to-header include edge but parses the `.c` and
+`.h` members separately.
 
 STB is treated as a family of independent single-file libraries: each
 top-level `.h` or `.c` input generates its own one-file project golden rather

tests/parser/c/README.md

@@ -22,10 +22,6 @@ cJSON corpus roadmap and compiler-preprocessed `.i`/`#line` behavior, which
 are not implemented yet. CLI, public API, and current project-resolution
 coverage are active.
 
-When `C_PARSER_UPDATE_GOLDENS=1` is set, golden inventory checks are skipped
-while their corresponding comparison tests rewrite the expected output. Those
-update-mode skips are workflow behavior, not unsupported parser input.
-
 ## Parser Goldens
 
 Active parser goldens cover grouped projects from `tests/data/c/general/`,
@@ -63,12 +59,6 @@ Regenerate selected projects by naming either input relative to
 python -m tests.parser.c.generate_c_parser_goldens general/math_api.c json/cJSON.h
 ```
 
-The fixture comparison test also supports the explicit update mode:
-
-```bash
-C_PARSER_UPDATE_GOLDENS=1 python -m pytest -q tests/parser/c/test_c_fixture_suite.py
-```
-
 ## Error Goldens
 
 Fatal diagnostic fixtures live in `tests/data/c/errors/parser/` and their
@@ -78,8 +68,6 @@ expected metadata lives in `fixtures/errors/`. Regenerate them with:
 python -m tests.parser.c.errors.generate_c_parser_error_goldens
 ```
 
-or update through the active regression test:
-
-```bash
-C_PARSER_UPDATE_GOLDENS=1 python -m pytest -q tests/parser/c/test_c_error_fixture_suite.py
-```
+The comparison tests are read-only. Regenerate the expected files with the
+standalone generator, then rerun the tests to compare against the checked-in
+baselines.

tests/parser/c/test_c_error_fixture_suite.py

@@ -2,7 +2,6 @@
 """C parser error fixture and diagnostic golden regression tests."""
 
 import json
-import os
 from pathlib import Path
 
 import pytest
@@ -28,9 +27,6 @@ def test_c_error_fixture_suite_has_fixtures():
 
 
 def test_c_error_fixtures_have_matching_expected_json():
-    if os.getenv("C_PARSER_UPDATE_GOLDENS", "0") == "1":
-        pytest.skip("Golden outputs are being updated by the diagnostic comparison test.")
-
     fixture_outputs = {
         f"{path.name}.json"
         for path in _ERRORS_DIR.glob("*")
@@ -45,31 +41,12 @@ def test_c_error_fixtures_have_matching_expected_json():
 def test_c_error_fixture_suite_reports_expected_diagnostics():
     from c_parser import CParseError, parse_c_file
 
-    update_mode = os.getenv("C_PARSER_UPDATE_GOLDENS", "0") == "1"
-
     for fixture in sorted(_ERRORS_DIR.glob("*")):
         if fixture.suffix.lower() not in _SOURCE_SUFFIXES:
             continue
         expected_path = _expected_path_for_fixture(fixture)
         source = fixture.read_text(encoding="utf-8")
 
-        if update_mode:
-            with pytest.raises(CParseError) as exc_info:
-                parse_c_file(source, filename=fixture.name)
-            payload = {
-                "parser": "parse_c_file",
-                "error_type": "CParseError",
-                "message_contains": [exc_info.value.base_message],
-                "diagnostic_contains": [
-                    f"error[{exc_info.value.code}]",
-                    exc_info.value.base_message,
-                    exc_info.value.source_line.strip() if exc_info.value.source_line else "",
-                ],
-            }
-            expected_path.parent.mkdir(parents=True, exist_ok=True)
-            expected_path.write_text(json.dumps(payload, indent=2) + "\n", encoding="utf-8")
-            continue
-
         expected = _load_expected_error(expected_path)
         assert expected["parser"] == "parse_c_file"
         assert expected["error_type"] == "CParseError"

tests/parser/c/test_c_fixture_suite.py

@@ -2,7 +2,6 @@
 """C parser grouped-project fixture/golden regression tests."""
 
 import json
-import os
 from pathlib import Path
 
 import pytest
@@ -110,9 +109,6 @@ def test_c_fixture_golden_suite_has_inputs(data_subdir):
 
 @pytest.mark.parametrize("data_subdir", _FIXTURE_GROUPS)
 def test_c_parser_project_goldens_match_fixture_stems_one_to_one(data_subdir):
-    if os.getenv("C_PARSER_UPDATE_GOLDENS", "0") == "1":
-        pytest.skip("Golden outputs are being updated by the comparison test.")
-
     data_root = _DATA_DIR / data_subdir
     fixture_root = _FIXTURES_DIR / data_subdir
 
@@ -125,17 +121,10 @@ def test_c_parser_project_goldens_match_fixture_stems_one_to_one(data_subdir):
 
 @pytest.mark.parametrize("data_subdir", _FIXTURE_GROUPS)
 def test_c_fixture_golden_suite_compares_project_json(data_subdir):
-    update_mode = os.getenv("C_PARSER_UPDATE_GOLDENS", "0") == "1"
-
     for project_key, fixtures in _project_groups(_DATA_DIR / data_subdir):
         expected_path = _expected_path_for_project(data_subdir, project_key)
         parsed = _serialize_project(fixtures)
 
-        if update_mode:
-            expected_path.parent.mkdir(parents=True, exist_ok=True)
-            expected_path.write_text(json.dumps(parsed, indent=2) + "\n", encoding="utf-8")
-            continue
-
         expected = json.loads(expected_path.read_text(encoding="utf-8"))
         assert parsed == expected