feat(experimentation): environment-scoped metrics & experiment results

api/audit/related_object_type.py

@@ -14,3 +14,4 @@ class RelatedObjectType(enum.Enum):
     RELEASE_PIPELINE = "Release pipeline"
     WAREHOUSE_CONNECTION = "Warehouse connection"
     EXPERIMENT = "Experiment"
+    METRIC = "Metric"

api/environments/urls.py

@@ -181,4 +181,8 @@
         "<str:environment_api_key>/experiments/",
         include("experimentation.experiment_urls"),
     ),
+    path(
+        "<str:environment_api_key>/experiment-metrics/",
+        include("experimentation.metric_urls"),
+    ),
 ]

api/experimentation/experiment_urls.py

@@ -1,10 +1,15 @@
-from rest_framework.routers import DefaultRouter
+from rest_framework_nested import routers  # type: ignore[import-untyped]
 
-from experimentation.views import ExperimentViewSet
+from experimentation.views import ExperimentMetricViewSet, ExperimentViewSet
 
 app_name = "experiments"
 
-router = DefaultRouter()
+router = routers.DefaultRouter()
 router.register(r"", ExperimentViewSet, basename="experiments")
 
-urlpatterns = router.urls
+experiments_router = routers.NestedSimpleRouter(router, r"", lookup="experiment")
+experiments_router.register(
+    r"metrics", ExperimentMetricViewSet, basename="experiment-metrics"
+)
+
+urlpatterns = router.urls + experiments_router.urls

api/experimentation/metric_definitions.py

@@ -0,0 +1,38 @@
+"""Versioned schemas for ``Metric.definition``.
+
+``definition`` is a schema-less JSON column whose shape is versioned so it can
+evolve without breaking stored rows. Each supported version has a validator
+here; the client sends the version it built the definition with. To introduce a
+new shape, add an entry to ``METRIC_DEFINITION_VALIDATORS``.
+"""
+
+from collections.abc import Callable
+
+DefinitionValidator = Callable[[dict[str, object]], "str | None"]
+
+
+def _validate_v1(definition: dict[str, object]) -> str | None:
+    event = definition.get("event")
+    if not event or not isinstance(event, str):
+        return "Definition must specify a non-empty 'event'."
+    return None
+
+
+METRIC_DEFINITION_VALIDATORS: dict[int, DefinitionValidator] = {
+    1: _validate_v1,
+}
+
+
+def validate_metric_definition(definition: object) -> str | None:
+    """Return an error message if ``definition`` is invalid, else ``None``."""
+    if not isinstance(definition, dict):
+        return "Definition must be an object."
+
+    version = definition.get("version")
+    validator = (
+        METRIC_DEFINITION_VALIDATORS.get(version) if isinstance(version, int) else None
+    )
+    if validator is None:
+        return "Definition must specify a supported 'version'."
+
+    return validator(definition)

api/experimentation/metric_urls.py

@@ -0,0 +1,10 @@
+from rest_framework.routers import DefaultRouter
+
+from experimentation.views import MetricViewSet
+
+app_name = "experiment_metrics"
+
+router = DefaultRouter()
+router.register(r"", MetricViewSet, basename="metrics")
+
+urlpatterns = router.urls

api/experimentation/migrations/0005_metrics.py

@@ -0,0 +1,136 @@
+# Generated by Django 5.2.14 on 2026-06-02 10:47
+
+import django.db.models.deletion
+import uuid
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("environments", "0037_add_uuid_field"),
+        ("experimentation", "0004_experiment"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="Metric",
+            fields=[
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                (
+                    "deleted_at",
+                    models.DateTimeField(
+                        blank=True,
+                        db_index=True,
+                        default=None,
+                        editable=False,
+                        null=True,
+                    ),
+                ),
+                (
+                    "uuid",
+                    models.UUIDField(default=uuid.uuid4, editable=False, unique=True),
+                ),
+                ("name", models.CharField(max_length=255)),
+                ("description", models.TextField(blank=True, default="")),
+                (
+                    "aggregation",
+                    models.CharField(
+                        choices=[
+                            ("count", "Count"),
+                            ("sum", "Sum"),
+                            ("mean", "Mean"),
+                            ("occurrence", "Occurrence (event happened at least once)"),
+                        ],
+                        default="mean",
+                        max_length=20,
+                    ),
+                ),
+                (
+                    "direction",
+                    models.CharField(
+                        choices=[
+                            ("up", "Higher is better"),
+                            ("down", "Lower is better"),
+                            ("informational", "Informational only"),
+                        ],
+                        default="up",
+                        max_length=20,
+                    ),
+                ),
+                ("definition", models.JSONField()),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                ("updated_at", models.DateTimeField(auto_now=True)),
+                (
+                    "environment",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="metrics",
+                        to="environments.environment",
+                    ),
+                ),
+            ],
+            options={
+                "abstract": False,
+            },
+        ),
+        migrations.CreateModel(
+            name="ExperimentMetric",
+            fields=[
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                (
+                    "expected_direction",
+                    models.CharField(
+                        choices=[
+                            ("increase", "Increase"),
+                            ("decrease", "Decrease"),
+                            ("not_increase", "Should not increase"),
+                            ("not_decrease", "Should not decrease"),
+                        ],
+                        max_length=20,
+                    ),
+                ),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                (
+                    "experiment",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="experiment_metrics",
+                        to="experimentation.experiment",
+                    ),
+                ),
+                (
+                    "metric",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="experiment_metrics",
+                        to="experimentation.metric",
+                    ),
+                ),
+            ],
+            options={
+                "constraints": [
+                    models.UniqueConstraint(
+                        fields=("experiment", "metric"),
+                        name="metric_attached_once_per_experiment",
+                    )
+                ],
+            },
+        ),
+    ]

api/experimentation/models.py

@@ -15,6 +15,7 @@
     add_environment_key_to_ingestion,
     delete_environment_key_from_ingestion,
 )
+from experimentation.types import MetricDefinition
 
 if typing.TYPE_CHECKING:
     from experimentation.dataclasses import WarehouseEventStats
@@ -126,3 +127,78 @@ class Meta:
                 name="unique_active_experiment_per_feature_env",
             ),
         ]
+
+
+class MetricAggregation(models.TextChoices):
+    COUNT = "count", "Count"
+    SUM = "sum", "Sum"
+    MEAN = "mean", "Mean"
+    OCCURRENCE = "occurrence", "Occurrence (event happened at least once)"
+
+
+class MetricDirection(models.TextChoices):
+    """A metric's inherent polarity — which way is "better"."""
+
+    UP = "up", "Higher is better"
+    DOWN = "down", "Lower is better"
+    INFORMATIONAL = "informational", "Informational only"
+
+
+class ExpectedDirection(models.TextChoices):
+    """The guardrail direction expected of a metric within an experiment."""
+
+    INCREASE = "increase", "Increase"
+    DECREASE = "decrease", "Decrease"
+    NOT_INCREASE = "not_increase", "Should not increase"
+    NOT_DECREASE = "not_decrease", "Should not decrease"
+
+
+class Metric(SoftDeleteExportableModel):
+    environment = models.ForeignKey(
+        Environment,
+        on_delete=models.CASCADE,
+        related_name="metrics",
+    )
+    name = models.CharField(max_length=255)
+    description = models.TextField(blank=True, default="")
+    aggregation = models.CharField(
+        max_length=20,
+        choices=MetricAggregation.choices,
+        default=MetricAggregation.MEAN,
+    )
+    direction = models.CharField(
+        max_length=20,
+        choices=MetricDirection.choices,
+        default=MetricDirection.UP,
+    )
+    definition: models.JSONField[MetricDefinition, MetricDefinition] = (
+        models.JSONField()
+    )
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+
+class ExperimentMetric(models.Model):
+    experiment = models.ForeignKey(
+        Experiment,
+        on_delete=models.CASCADE,
+        related_name="experiment_metrics",
+    )
+    metric = models.ForeignKey(
+        Metric,
+        on_delete=models.CASCADE,
+        related_name="experiment_metrics",
+    )
+    expected_direction = models.CharField(
+        max_length=20,
+        choices=ExpectedDirection.choices,
+    )
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        constraints = [
+            models.UniqueConstraint(
+                fields=["experiment", "metric"],
+                name="metric_attached_once_per_experiment",
+            ),
+        ]

api/experimentation/permissions.py

@@ -40,3 +40,7 @@ def has_permission(self, request: Request, view: APIView) -> bool:
 
         user: FFAdminUser = request.user  # type: ignore[assignment]
         return user.is_environment_admin(environment)
+
+
+# Metrics are gated identically to experiments; aliased until the rules diverge.
+MetricPermission = ExperimentPermission