AFI conformance test suite

Substrate-level gate: same @client fixture registered in both backends
emits equivalent schemas, therefore the codegen produces equivalent
TypeScript regardless of which backend the frontend is generated against.
Catches adapter symmetry problems (Pydantic→OpenAPI converter divergence,
metadata leakage, ordering non-determinism) without docker, browser, or
Playwright.

What ships:

backends/mizan-fastapi/src/mizan_fastapi/schema.py — build_schema():
- Builds OpenAPI 3.0 from registered Mizan functions, mirroring the
  shape mizan-django's export emits.
- Drives FastAPI's native OpenAPI generation by registering a stub POST
  endpoint per function with its Input/Output Pydantic models, then
  appends x-mizan-functions and x-mizan-contexts extensions.
- Param-elevation logic mirrors mizan-django/src/mizan/export/__init__.py
  exactly (sharedBy tracking, required iff every function in context has
  the param).
- snake_to_camel and metadata field shapes match Django for byte-equality
  on the AFI surface.

tests/afi/ — the conformance harness:
- fixture.py: 5 @client functions covering the protocol axes (plain,
  context, mutation+affects). No channels/forms — those aren't AFI-common.
- django_app/: minimal Django project (settings, urls, AppConfig.ready
  registers the fixture). manage.py adds tests/afi/ to sys.path so both
  backends import the same fixture module.
- fastapi_app.py: thin make_app() that registers fixture and mounts router.
- schema_normalizer.py: drops backend-specific framing — Ninja-vs-FastAPI
  envelope differences (info/servers/tags), Django-only function fields
  (form metadata), x-mizan-channels. Plus afi_subset() and
  function_io_schemas() helpers for narrower comparisons.
- test_codegen_parity.py: three gates
  1. x-mizan-functions match across backends
  2. x-mizan-contexts match across backends
  3. Per-function Input/Output OpenAPI schemas match (what codegen feeds
     to openapi-typescript for type generation)

The full normalized OpenAPI envelopes do diverge — FastAPI adds
HTTPValidationError, the two converters wrap things slightly differently
in non-AFI-essential ways. That's not in the test scope. The codegen
only consumes x-mizan-functions, x-mizan-contexts, and the per-function
type schemas; those are what the test gates.

Makefile: test-afi target added; rolls into the test aggregate.

Verified: 3/3 conformance tests pass. Other surfaces unaffected —
mizan-core 15/15, mizan-django 348 pass, mizan-fastapi 11/11.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/afi/django_app/afi_app/__init__.py

@@ -0,0 +1 @@
+default_app_config = "afi_app.apps.AfiAppConfig"

tests/afi/django_app/afi_app/apps.py

@@ -0,0 +1,13 @@
+"""Django app config that registers the AFI fixture on Django's ready() hook."""
+
+from django.apps import AppConfig
+
+
+class AfiAppConfig(AppConfig):
+    name = "afi_app"
+
+    def ready(self) -> None:
+        # tests/afi/ is on sys.path (added by manage.py), so `fixture` resolves
+        # to tests/afi/fixture.py — the same module the FastAPI side imports.
+        from fixture import register_fixture
+        register_fixture()

tests/afi/django_app/manage.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python
+"""Minimal Django manage.py for the AFI conformance fixture."""
+
+import os
+import sys
+
+
+def main() -> None:
+    here = os.path.dirname(os.path.abspath(__file__))
+    # tests/afi/ must be on sys.path so apps.py can `from fixture import …`.
+    sys.path.insert(0, os.path.dirname(here))
+    sys.path.insert(0, here)
+    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "project.settings")
+    from django.core.management import execute_from_command_line
+    execute_from_command_line(sys.argv)
+
+
+if __name__ == "__main__":
+    main()

tests/afi/django_app/project/settings.py

@@ -0,0 +1,20 @@
+"""Minimal Django settings for the AFI conformance fixture."""
+
+SECRET_KEY = "afi-conformance-test-only"
+DEBUG = True
+ALLOWED_HOSTS = ["*"]
+
+INSTALLED_APPS = [
+    "django.contrib.contenttypes",
+    "django.contrib.auth",
+    "mizan",
+    "afi_app",
+]
+
+DATABASES = {
+    "default": {"ENGINE": "django.db.backends.sqlite3", "NAME": ":memory:"},
+}
+
+ROOT_URLCONF = "project.urls"
+USE_TZ = True
+DEFAULT_AUTO_FIELD = "django.db.models.BigAutoField"

tests/afi/django_app/project/urls.py

@@ -0,0 +1,3 @@
+"""Empty URLconf — the AFI fixture only exercises the schema export."""
+
+urlpatterns: list = []

tests/afi/fastapi_app.py

@@ -0,0 +1,26 @@
+"""FastAPI test app that registers the AFI fixture and exposes build_schema()."""
+
+from __future__ import annotations
+
+from fastapi import FastAPI
+
+from mizan_fastapi import (
+    MizanError,
+    mizan_exception_handler,
+    mizan_validation_handler,
+    router as mizan_router,
+)
+
+from fixture import register_fixture
+
+
+def make_app() -> FastAPI:
+    """Build a fresh FastAPI app with the AFI fixture registered."""
+    register_fixture()
+
+    app = FastAPI()
+    app.include_router(mizan_router, prefix="/api/mizan")
+    app.add_exception_handler(MizanError, mizan_exception_handler)
+    from fastapi.exceptions import RequestValidationError
+    app.add_exception_handler(RequestValidationError, mizan_validation_handler)
+    return app

tests/afi/fixture.py

@@ -0,0 +1,94 @@
+"""
+The AFI fixture — a small set of @client-decorated functions designed to
+exercise the protocol axes both backends must agree on:
+
+- plain function with typed input
+- plain function with no input
+- two context functions sharing a param (proves bundling + param elevation)
+- a mutation declaring `affects` on the context
+
+No channels, no forms, no shapes — those aren't AFI-common.
+
+`register_fixture()` registers the functions with mizan_core.registry.
+Backend test apps import this module and call register_fixture() during
+their setup so each backend's schema export sees the same registrations.
+"""
+
+from __future__ import annotations
+
+from pydantic import BaseModel
+
+from mizan_core.client.function import client
+from mizan_core.registry import register
+
+
+# ─── Output shapes ──────────────────────────────────────────────────────────
+
+
+class EchoOutput(BaseModel):
+    message: str
+
+
+class WhoamiOutput(BaseModel):
+    email: str
+    authenticated: bool
+
+
+class ProfileOutput(BaseModel):
+    user_id: int
+    name: str
+
+
+class OrderOutput(BaseModel):
+    id: int
+    user_id: int
+    total: int
+
+
+class StatusOutput(BaseModel):
+    ok: bool
+
+
+# ─── Fixture functions ──────────────────────────────────────────────────────
+
+
+@client
+def echo(request, text: str) -> EchoOutput:
+    """Echoes the input back."""
+    return EchoOutput(message=f"echo: {text}")
+
+
+@client
+def whoami(request) -> WhoamiOutput:
+    """Returns the current user identity."""
+    return WhoamiOutput(email="anon@example.com", authenticated=False)
+
+
+@client(context="user")
+def user_profile(request, user_id: int) -> ProfileOutput:
+    """One half of the user context."""
+    return ProfileOutput(user_id=user_id, name="placeholder")
+
+
+@client(context="user")
+def user_orders(request, user_id: int) -> list[OrderOutput]:
+    """Other half of the user context — same param, proves param elevation."""
+    return []
+
+
+@client(affects="user")
+def update_profile(request, user_id: int, name: str) -> StatusOutput:
+    """Mutation declaring affects on the user context."""
+    return StatusOutput(ok=True)
+
+
+# ─── Registration ───────────────────────────────────────────────────────────
+
+
+def register_fixture() -> None:
+    """Register every fixture function with mizan_core.registry."""
+    register(echo, "echo")
+    register(whoami, "whoami")
+    register(user_profile, "user_profile")
+    register(user_orders, "user_orders")
+    register(update_profile, "update_profile")

tests/afi/pyproject.toml

@@ -0,0 +1,22 @@
+[project]
+name = "mizan-afi-tests"
+version = "0.0.0"
+description = "AFI conformance tests — verifies mizan-django and mizan-fastapi emit equivalent schemas for the same registered functions."
+requires-python = ">=3.10"
+dependencies = [
+    "mizan-core",
+    "mizan",
+    "mizan-fastapi",
+    "pytest>=8.0",
+]
+
+[tool.uv.sources]
+mizan-core = { path = "../../cores/mizan-python", editable = true }
+mizan = { path = "../../backends/mizan-django", editable = true }
+mizan-fastapi = { path = "../../backends/mizan-fastapi", editable = true }
+
+[tool.pytest.ini_options]
+pythonpath = ["."]
+testpaths = ["."]
+python_classes = ["*Tests", "*Test", "Test*"]
+python_functions = ["test_*"]

tests/afi/schema_normalizer.py

@@ -0,0 +1,79 @@
+"""
+Normalize an OpenAPI schema dict so backend-specific framing doesn't make
+two semantically-equivalent schemas compare unequal.
+
+Drops:
+- Top-level OpenAPI envelope fields that vary trivially (info, servers, tags)
+- Django-only x-mizan-functions sub-fields (form metadata)
+- Django-only top-level extensions (x-mizan-channels)
+
+Sorts:
+- x-mizan-functions by name
+- components.schemas keys
+"""
+
+from __future__ import annotations
+
+from copy import deepcopy
+from typing import Any
+
+
+_DJANGO_ONLY_FUNCTION_FIELDS = {"isForm", "formName", "formRole", "formFields", "formFieldsError"}
+
+_OPENAPI_ENVELOPE_FIELDS_TO_DROP = {"info", "servers", "tags", "openapi"}
+
+
+def normalize(schema: dict[str, Any]) -> dict[str, Any]:
+    """Return a canonicalized copy suitable for deep-equal comparison."""
+    out = deepcopy(schema)
+
+    for k in _OPENAPI_ENVELOPE_FIELDS_TO_DROP:
+        out.pop(k, None)
+
+    out.pop("x-mizan-channels", None)
+
+    fns = out.get("x-mizan-functions") or []
+    for fn in fns:
+        for field in _DJANGO_ONLY_FUNCTION_FIELDS:
+            fn.pop(field, None)
+    out["x-mizan-functions"] = sorted(fns, key=lambda f: f["name"])
+
+    components = out.get("components", {})
+    schemas = components.get("schemas")
+    if isinstance(schemas, dict):
+        components["schemas"] = {k: schemas[k] for k in sorted(schemas)}
+
+    return out
+
+
+def afi_subset(schema: dict[str, Any]) -> dict[str, Any]:
+    """Just the AFI-essential surface — what every adapter must agree on."""
+    fns = schema.get("x-mizan-functions") or []
+    fns_clean = [
+        {k: v for k, v in fn.items() if k not in _DJANGO_ONLY_FUNCTION_FIELDS}
+        for fn in fns
+    ]
+    return {
+        "x-mizan-functions": sorted(fns_clean, key=lambda f: f["name"]),
+        "x-mizan-contexts": schema.get("x-mizan-contexts", {}),
+    }
+
+
+def function_io_schemas(schema: dict[str, Any]) -> dict[str, Any]:
+    """
+    Subset of components.schemas containing only the per-function Input/Output
+    models (what the codegen actually consumes for TypeScript type generation).
+    Drops backend-specific noise like HTTPValidationError, ValidationError,
+    that one backend emits and the other doesn't.
+    """
+    fns = schema.get("x-mizan-functions") or []
+    expected_names: set[str] = set()
+    for fn in fns:
+        if fn.get("inputType"):
+            expected_names.add(fn["inputType"])
+        if fn.get("outputType"):
+            expected_names.add(fn["outputType"])
+
+    components = schema.get("components", {})
+    schemas = components.get("schemas", {})
+    return {name: schemas[name] for name in sorted(expected_names) if name in schemas}

tests/afi/test_codegen_parity.py

@@ -0,0 +1,88 @@
+"""
+AFI conformance — same @client fixture, same schema, both adapters.
+
+Gates that mizan-django and mizan-fastapi emit equivalent schemas for the
+same registered functions. If this passes, the codegen produces equivalent
+TypeScript output regardless of which backend the frontend is generated
+against (codegen is deterministic over schema input).
+
+This is a substrate-level gate, not e2e. It catches adapter symmetry
+problems — Pydantic→OpenAPI converter divergence, metadata leakage,
+ordering non-determinism — without running a real frontend or backend.
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+HERE = Path(__file__).parent
+DJANGO_MANAGE = HERE / "django_app" / "manage.py"
+
+
+# ─── Schema fetchers ────────────────────────────────────────────────────────
+
+
+def _fetch_django_schema() -> dict:
+    """Spawn Django's management command and parse its stdout JSON."""
+    result = subprocess.run(
+        [sys.executable, str(DJANGO_MANAGE), "export_mizan_schema", "--indent", "0"],
+        capture_output=True,
+        text=True,
+        check=False,
+        env={**os.environ, "PYTHONDONTWRITEBYTECODE": "1"},
+    )
+    if result.returncode != 0:
+        pytest.fail(f"export_mizan_schema failed:\nstdout:\n{result.stdout}\nstderr:\n{result.stderr}")
+    return json.loads(result.stdout)
+
+
+def _fetch_fastapi_schema() -> dict:
+    """Build the FastAPI app inline (fresh registry) and call build_schema()."""
+    sys.path.insert(0, str(HERE))
+    try:
+        from mizan_core.registry import clear_registry
+        from mizan_fastapi import build_schema
+        from fastapi_app import make_app
+
+        clear_registry()
+        make_app()
+        return build_schema()
+    finally:
+        sys.path.remove(str(HERE))
+
+
+# ─── Tests ──────────────────────────────────────────────────────────────────
+
+
+@pytest.fixture(scope="module")
+def schemas() -> tuple[dict, dict]:
+    return _fetch_django_schema(), _fetch_fastapi_schema()
+
+
+class AFISubsetTests:
+    """The AFI surface — x-mizan-functions and x-mizan-contexts — must match."""
+
+    def test_x_mizan_functions_match(self, schemas):
+        from schema_normalizer import afi_subset
+        django, fastapi = schemas
+        assert afi_subset(django)["x-mizan-functions"] == afi_subset(fastapi)["x-mizan-functions"]
+
+    def test_x_mizan_contexts_match(self, schemas):
+        from schema_normalizer import afi_subset
+        django, fastapi = schemas
+        assert afi_subset(django)["x-mizan-contexts"] == afi_subset(fastapi)["x-mizan-contexts"]
+
+
+class TypeSchemasTests:
+    """Per-function Input/Output Pydantic→OpenAPI schemas — codegen feeds these to openapi-typescript."""
+
+    def test_function_io_schemas_match(self, schemas):
+        from schema_normalizer import function_io_schemas
+        django, fastapi = schemas
+        assert function_io_schemas(django) == function_io_schemas(fastapi)