fix error in gitignore

apps/processing/models.py

@@ -0,0 +1,43 @@
+from django.db import models
+
+from apps.core.models import TimeStampedModel, UUIDModel
+
+
+class StepExecution(UUIDModel, TimeStampedModel):
+    class State(models.TextChoices):
+        PENDING = "pending", "Pending"
+        READY = "ready", "Ready"
+        IN_PROGRESS = "in_progress", "In progress"
+        PAUSED = "paused", "Paused"
+        WAITING = "waiting", "Waiting"
+        COMPLETED = "completed", "Completed"
+        FAILED = "failed", "Failed"
+        REJECTED = "rejected", "Rejected"
+        SKIPPED = "skipped", "Skipped"
+        CANCELLED = "cancelled", "Cancelled"
+        REWORK_REQUIRED = "rework_required", "Rework required"
+
+    order = models.ForeignKey("orders.ProcessingOrder", on_delete=models.CASCADE, related_name="step_executions")
+    step = models.ForeignKey("workflows.WorkflowStep", on_delete=models.PROTECT)
+    state = models.CharField(max_length=20, choices=State.choices, default=State.PENDING)
+    attempt = models.PositiveIntegerField(default=1)
+    assigned_to = models.ForeignKey(
+        "accounts.User", null=True, blank=True, on_delete=models.SET_NULL, related_name="assigned_steps"
+    )
+    started_at = models.DateTimeField(null=True, blank=True)
+    completed_at = models.DateTimeField(null=True, blank=True)
+    notes = models.TextField(blank=True)
+    measurements = models.JSONField(default=dict, blank=True)
+    # For rework history: a rework execution points back to the failed one.
+    parent = models.ForeignKey(
+        "self", null=True, blank=True, on_delete=models.SET_NULL, related_name="rework_children"
+    )
+
+    class Meta:
+        ordering = ["created_at"]
+        constraints = [
+            models.UniqueConstraint(fields=["order", "step", "attempt"], name="uniq_step_execution_attempt")
+        ]
+
+    def __str__(self) -> str:
+        return f"{self.order.order_number} / {self.step.key} (attempt {self.attempt})"