feat: add maintenance tree_type with db migration and tests

- Expand ck_trees_tree_type CHECK constraint to include 'maintenance'
- Add 'maintenance' to TreeType Literal in schemas
- Treat maintenance trees as procedural in can_publish_tree validation
- Alembic migration 0f1ca2af3647 drops and recreates the constraint
- Two integration tests: create and filter by tree_type=maintenance

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

backend/alembic/versions/0f1ca2af3647_add_maintenance_tree_type.py

@@ -0,0 +1,33 @@
+"""add maintenance tree type
+
+Revision ID: 0f1ca2af3647
+Revises: 039
+Create Date: 2026-02-17 10:25:54.959861
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = '0f1ca2af3647'
+down_revision: Union[str, None] = '039'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.execute("ALTER TABLE trees DROP CONSTRAINT ck_trees_tree_type")
+    op.execute(
+        "ALTER TABLE trees ADD CONSTRAINT ck_trees_tree_type "
+        "CHECK (tree_type IN ('troubleshooting', 'procedural', 'maintenance'))"
+    )
+
+
+def downgrade() -> None:
+    op.execute("UPDATE trees SET tree_type = 'procedural' WHERE tree_type = 'maintenance'")
+    op.execute("ALTER TABLE trees DROP CONSTRAINT ck_trees_tree_type")
+    op.execute(
+        "ALTER TABLE trees ADD CONSTRAINT ck_trees_tree_type "
+        "CHECK (tree_type IN ('troubleshooting', 'procedural'))"
+    )

backend/app/core/tree_validation.py

@@ -224,14 +224,14 @@ def can_publish_tree(
         errors.append({"field": "name", "message": "Tree must have a name to be published"})
 
     # Validate structure based on tree type
-    if tree_type == "procedural":
+    if tree_type in ("procedural", "maintenance"):
         structure_valid, structure_errors = validate_procedural_structure(tree_structure)
     else:
         structure_valid, structure_errors = validate_tree_structure(tree_structure)
     errors.extend(structure_errors)
 
     # Validate intake form if present (procedural only)
-    if intake_form and tree_type == "procedural":
+    if intake_form and tree_type in ("procedural", "maintenance"):
         form_valid, form_errors = _validate_intake_form(intake_form)
         errors.extend(form_errors)
 

backend/app/models/tree.py

@@ -29,7 +29,7 @@ class Tree(Base):
             name='ck_trees_status'
         ),
         CheckConstraint(
-            "tree_type IN ('troubleshooting', 'procedural')",
+            "tree_type IN ('troubleshooting', 'procedural', 'maintenance')",
             name='ck_trees_tree_type'
         ),
     )

backend/app/schemas/tree.py

@@ -7,7 +7,7 @@ import re
 
 # --- Tree Type ---
 
-TreeType = Literal['troubleshooting', 'procedural']
+TreeType = Literal['troubleshooting', 'procedural', 'maintenance']
 
 # --- Intake Form Schemas ---
 

backend/tests/test_maintenance_tree_type.py

@@ -0,0 +1,52 @@
+"""Tests for maintenance tree type."""
+import pytest
+from httpx import AsyncClient
+
+
+@pytest.mark.asyncio
+async def test_create_maintenance_tree(client: AsyncClient, auth_headers: dict):
+    """Maintenance tree type is accepted by the API."""
+    resp = await client.post(
+        "/api/v1/trees",
+        json={
+            "name": "Update FSLogix",
+            "description": "Monthly FSLogix update procedure",
+            "tree_type": "maintenance",
+            "tree_structure": {
+                "steps": [
+                    {"id": "step-1", "type": "procedure_step", "title": "Download installer",
+                     "description": "Get latest FSLogix from Microsoft", "content_type": "action"},
+                    {"id": "step-end", "type": "procedure_end", "title": "Complete"},
+                ]
+            },
+        },
+        headers=auth_headers,
+    )
+    assert resp.status_code == 201, resp.text
+    data = resp.json()
+    assert data["tree_type"] == "maintenance"
+
+
+@pytest.mark.asyncio
+async def test_list_maintenance_trees_filter(client: AsyncClient, auth_headers: dict):
+    """Filtering by tree_type=maintenance returns only maintenance trees."""
+    await client.post(
+        "/api/v1/trees",
+        json={
+            "name": "Maintenance Only",
+            "tree_type": "maintenance",
+            "tree_structure": {
+                "steps": [
+                    {"id": "s1", "type": "procedure_step", "title": "Step",
+                     "description": "Do it", "content_type": "action"},
+                    {"id": "end", "type": "procedure_end", "title": "Done"},
+                ]
+            },
+        },
+        headers=auth_headers,
+    )
+    resp = await client.get("/api/v1/trees?tree_type=maintenance", headers=auth_headers)
+    assert resp.status_code == 200
+    trees = resp.json()
+    assert all(t["tree_type"] == "maintenance" for t in trees)
+    assert len(trees) >= 1