Add auto_assign_monthly_targets tool

src/server/__init__.py

@@ -15,6 +15,7 @@
     list_categories, get_category, create_category, update_category,
     create_category_group, update_category_group,
     get_category_for_month, update_category_for_month,
+    auto_assign_monthly_targets,
 )
 from src.server.payees import list_payees, get_payee, update_payee
 from src.server.payee_locations import (
@@ -44,6 +45,7 @@
     "list_categories", "get_category", "create_category", "update_category",
     "create_category_group", "update_category_group",
     "get_category_for_month", "update_category_for_month",
+    "auto_assign_monthly_targets",
     "list_payees", "get_payee", "update_payee",
     "list_payee_locations", "get_payee_location", "get_payee_locations_by_payee",
     "list_money_movements", "get_money_movements_for_month",

src/server/categories.py

@@ -1,3 +1,5 @@
+from datetime import date
+
 from src.server import _shared
 from src.server._shared import dollars_to_milliunits, serialize, serialize_list
 
@@ -7,6 +9,12 @@
     "Pass [] to return all fields. Pass a custom list to override the default."
 )
 
+AUTO_ASSIGN_SKIP_GROUPS = {
+    "Internal Master Category",
+    "Credit Card Payments",
+    "Hidden Categories",
+}
+
 
 @_shared.mcp.tool()
 @_shared.handle_errors
@@ -214,3 +222,52 @@ async def update_category_for_month(
         month, category_id, dollars_to_milliunits(budgeted), plan_id
     )
     return serialize(cat, exclude_fields=exclude_fields)
+
+
+@_shared.mcp.tool()
+@_shared.handle_errors
+async def auto_assign_monthly_targets(plan_id: str, month: str = "current") -> str:
+    """Assign budgets to all categories based on their goal targets.
+
+    Mirrors YNAB's Auto-Assign -> Monthly Targets button. For every category
+    that has a goal_target set, assigns the goal amount as the budgeted value
+    for the given month. Skips hidden, deleted, and internal groups
+    (Internal Master Category, Credit Card Payments, Hidden Categories).
+
+    Args:
+        plan_id: The plan ID (use list_plans to find available IDs)
+        month: Month in YYYY-MM-DD format (e.g. '2026-05-01') or 'current'. Defaults to current month.
+    """
+    import json
+
+    if month == "current":
+        today = date.today()
+        month = today.replace(day=1).strftime("%Y-%m-%d")
+
+    groups = await _shared.cache.get_categories(plan_id)
+    assignments = []
+    for group in groups:
+        if group.name in AUTO_ASSIGN_SKIP_GROUPS or group.hidden or group.deleted:
+            continue
+        for cat in group.categories:
+            if cat.hidden or cat.deleted or not cat.goal_target:
+                continue
+            updated = await _shared.cache.update_category_for_month(
+                month, cat.id, cat.goal_target, plan_id
+            )
+            assignments.append({
+                "name": updated.name,
+                "group": group.name,
+                "budgeted": updated.budgeted / 1000,
+            })
+
+    total = sum(a["budgeted"] for a in assignments)
+    return json.dumps(
+        {
+            "month": month,
+            "categories_assigned": len(assignments),
+            "total_budgeted": round(total, 2),
+            "assignments": assignments,
+        },
+        indent=2,
+    )

tests/test_server.py

@@ -470,6 +470,70 @@ async def test_converts_dollars_to_milliunits(self, mock_cache):
         assert call_args[0][2] == 500000  # third positional arg is budgeted in milliunits
 
 
+class TestAutoAssignMonthlyTargets:
+    @pytest.mark.asyncio
+    async def test_assigns_categories_with_goal_targets(self, mock_cache):
+        from src.server import auto_assign_monthly_targets
+
+        bills = _make_category_group(id="grp-1", name="Bills")
+        bills.categories = [
+            _make_category(id="c1", name="Rent", goal_target=1500000),
+            _make_category(id="c2", name="Utilities", goal_target=200000),
+            _make_category(id="c3", name="Unset", goal_target=None),
+        ]
+        mock_cache.get_categories = AsyncMock(return_value=[bills])
+        mock_cache.update_category_for_month = AsyncMock(
+            side_effect=lambda month, cid, milli, pid: _make_category(
+                id=cid, name={"c1": "Rent", "c2": "Utilities"}[cid], budgeted=milli
+            )
+        )
+
+        result = json.loads(await auto_assign_monthly_targets(
+            plan_id="bud-1", month="2026-04-01"
+        ))
+
+        assert result["categories_assigned"] == 2
+        assert result["total_budgeted"] == 1700.0
+        assert mock_cache.update_category_for_month.call_count == 2
+
+    @pytest.mark.asyncio
+    async def test_skips_internal_groups_and_hidden_categories(self, mock_cache):
+        from src.server import auto_assign_monthly_targets
+
+        internal = _make_category_group(id="grp-i", name="Internal Master Category")
+        internal.categories = [_make_category(id="ix", goal_target=100000)]
+        cc = _make_category_group(id="grp-cc", name="Credit Card Payments")
+        cc.categories = [_make_category(id="cx", goal_target=100000)]
+        bills = _make_category_group(id="grp-1", name="Bills")
+        bills.categories = [
+            _make_category(id="c1", goal_target=1000000, hidden=True),
+            _make_category(id="c2", goal_target=500000, deleted=True),
+            _make_category(id="c3", goal_target=300000),
+        ]
+        mock_cache.get_categories = AsyncMock(return_value=[internal, cc, bills])
+        mock_cache.update_category_for_month = AsyncMock(
+            return_value=_make_category(id="c3", budgeted=300000)
+        )
+
+        result = json.loads(await auto_assign_monthly_targets(
+            plan_id="bud-1", month="2026-04-01"
+        ))
+
+        assert result["categories_assigned"] == 1
+        mock_cache.update_category_for_month.assert_called_once()
+        assert mock_cache.update_category_for_month.call_args[0][1] == "c3"
+
+    @pytest.mark.asyncio
+    async def test_resolves_current_to_first_of_month(self, mock_cache):
+        from src.server import auto_assign_monthly_targets
+
+        mock_cache.get_categories = AsyncMock(return_value=[])
+        result = json.loads(await auto_assign_monthly_targets(plan_id="bud-1"))
+        # month is normalized to YYYY-MM-01
+        assert result["month"].endswith("-01")
+        assert len(result["month"]) == 10
+
+
 # ── Payee Tools ───────────────────────────────────────────────