test(gui_2): add Phase 1 invariant tests (test_gui_2_result.py, 2 tests)

TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 1.

Adds tests/test_gui_2_result.py with 2 Phase 1 invariant tests:

1. test_phase_1_inventory_has_42_rows: parses
   tests/artifacts/PHASE1_SITE_INVENTORY.md and asserts the Site
   Inventory table contains exactly 42 rows.

2. test_phase_1_audit_has_42_migration_target_sites: runs
   scripts/audit_exception_handling.py --src src --json, finds the
   src/gui_2.py file record, counts sites in the migration-target
   category set (excludes INTERNAL_COMPLIANT, INTERNAL_PROGRAMMER_RAISE,
   BOUNDARY_FASTAPI, BOUNDARY_SDK, BOUNDARY_CONVERSION), and asserts the
   count is 42.

This locks the 42-site migration target count: if the audit heuristic
or inventory drift, the test catches it before Phase 2.

Both tests pass:
  tests/test_gui_2_result.py::test_phase_1_inventory_has_42_rows PASSED
  tests/test_gui_2_result.py::test_phase_1_audit_has_42_migration_target_sites PASSED

tests/test_gui_2_result.py

@@ -0,0 +1,119 @@
+"""
+Tests for the Phase 1 invariant contract of result_migration_gui_2_20260619.
+
+This file locks the Phase 1 site inventory contract: there are exactly 42
+migration-target error-handling sites in src/gui_2.py. Both tests are static
+invariants that must pass before Phase 1 closes and Phase 2 begins:
+
+- test_phase_1_inventory_has_42_rows: parses the markdown inventory table
+  (tests/artifacts/PHASE1_SITE_INVENTORY.md) and asserts the Site Inventory
+  table contains exactly 42 rows.
+- test_phase_1_audit_has_42_migration_target_sites: invokes the audit script
+  (scripts/audit_exception_handling.py --src src --json), finds the
+  src/gui_2.py file record, and counts the sites whose category is in the
+  migration-target set (i.e., NOT INTERNAL_COMPLIANT, NOT
+  INTERNAL_PROGRAMMER_RAISE, NOT BOUNDARY_*).
+
+The migration-target category set is defined per
+conductor/code_styleguides/error_handling.md as: any category that is not one
+of the 5 "leave-as-is" categories. The migration-target sites are the ones
+the Phase 2-N migration will touch; the leave-as-is categories are legitimate
+non-migration patterns (compliant internal try/except, programmer raises,
+and the 3 boundary categories).
+"""
+import json
+import re
+import subprocess
+from pathlib import Path
+
+
+INVENTORY_PATH = Path("tests/artifacts/PHASE1_SITE_INVENTORY.md")
+EXPECTED_SITE_COUNT = 42
+MIGRATION_EXCLUDE_CATEGORIES = frozenset({
+ "INTERNAL_COMPLIANT",
+ "INTERNAL_PROGRAMMER_RAISE",
+ "BOUNDARY_FASTAPI",
+ "BOUNDARY_SDK",
+ "BOUNDARY_CONVERSION",
+})
+
+
+def test_phase_1_inventory_has_42_rows():
+ """
+ Parse tests/artifacts/PHASE1_SITE_INVENTORY.md and verify the "Site Inventory"
+ markdown table contains exactly 42 rows.
+
+ The Site Inventory table begins with a header row of the form
+ "| L# | Category | Phase | ..." and a separator row "|---...". Each data row
+ has the form "| <line_number> | <CATEGORY> | <phase_number> | ...". The test
+ locates the header by its leading "| L#" sentinel and counts subsequent rows
+ that match the data-row pattern until the first non-table line.
+ """
+ text = INVENTORY_PATH.read_text(encoding="utf-8")
+ lines = text.splitlines()
+ header_idx = None
+ for i, line in enumerate(lines):
+  if line.startswith("| L#"):
+   header_idx = i
+   break
+ assert header_idx is not None, (
+  f"Could not find '| L#' header in {INVENTORY_PATH}. "
+  f"The inventory file format may have changed."
+ )
+ rows = []
+ for line in lines[header_idx + 2:]:
+  if not line.startswith("|"):
+   break
+  if re.match(r"^\|\s*\d+\s*\|", line):
+   rows.append(line)
+ assert len(rows) == EXPECTED_SITE_COUNT, (
+  f"PHASE1_SITE_INVENTORY.md has {len(rows)} site rows; expected "
+  f"{EXPECTED_SITE_COUNT}. The inventory must list exactly 42 migration-target "
+  f"sites in src/gui_2.py."
+ )
+
+
+def test_phase_1_audit_has_42_migration_target_sites():
+ """
+ Invoke scripts/audit_exception_handling.py --src src --json, parse the JSON
+ output, and verify that the src/gui_2.py file record contains exactly 42
+ sites in the migration-target category set.
+
+ A site is "migration-target" when its category is NOT one of:
+ - INTERNAL_COMPLIANT (legitimate compliant internal try/except)
+ - INTERNAL_PROGRAMMER_RAISE (raise for impossible/programmer states)
+ - BOUNDARY_FASTAPI (FastAPI HTTPException boundary)
+ - BOUNDARY_SDK (SDK call boundary conversion)
+ - BOUNDARY_CONVERSION (broad except used as conversion boundary)
+
+ The migration-target set is therefore:
+ INTERNAL_BROAD_CATCH | INTERNAL_SILENT_SWALLOW | INTERNAL_RETHROW |
+ INTERNAL_OPTIONAL_RETURN | UNCLEAR.
+
+ This test pins the audit output to the same 42 the inventory declares, so a
+ future audit-script regression or inventory drift will surface here.
+ """
+ result = subprocess.run(
+  ["uv", "run", "python", "scripts/audit_exception_handling.py", "--src", "src", "--json"],
+  capture_output=True,
+  text=True,
+ )
+ assert result.returncode == 0, (
+  f"audit_exception_handling.py exited {result.returncode}; stderr:\n"
+  f"{result.stderr[:2000]}"
+ )
+ data = json.loads(result.stdout)
+ gui2_files = [f for f in data.get("files", []) if "gui_2" in f.get("filename", "")]
+ assert gui2_files, (
+  "audit JSON contained no file record matching 'gui_2' in filename. "
+  f"Filenames seen: {[f.get('filename') for f in data.get('files', [])][:10]}"
+ )
+ gui2 = gui2_files[0]
+ findings = gui2.get("findings", [])
+ migration_sites = [f for f in findings if f.get("category") not in MIGRATION_EXCLUDE_CATEGORIES]
+ assert len(migration_sites) == EXPECTED_SITE_COUNT, (
+  f"src/gui_2.py has {len(migration_sites)} migration-target sites in the audit; "
+  f"expected {EXPECTED_SITE_COUNT}. Categories seen: "
+  f"{sorted({f.get('category') for f in migration_sites})}. "
+  f"This must match the 42 sites declared in PHASE1_SITE_INVENTORY.md."
+ )