fix: deep custom config should be optional

src/config.ts

@@ -57,8 +57,8 @@ export const settings = z.discriminatedUnion("mode", [
             "fast-hi": customAssignment,
             "good-lo": customAssignment,
             "good-hi": customAssignment,
-            "deep-lo": customAssignment,
-            "deep-hi": customAssignment,
+            "deep-lo": customAssignment.optional(),
+            "deep-hi": customAssignment.optional(),
             // Deprecated compatibility field. Coordinate is derived from deep-lo/good-lo.
             coordinate: customAssignment.optional(),
         }),

src/index.ts

@@ -204,17 +204,20 @@ const makeBasePlugin = (permissionsChanged: (permissions: Agent.Info["permission
                         model: assignment.model.slice(slash + 1),
                     };
                 };
-                const availableFor = (
-                    assignment: (typeof assignments)[(typeof workerNames)[number]],
-                ) => {
+                const availableFor = (assignment: { model: string }) => {
                     const { provider, model } = coordinates(assignment);
                     return models.get(modelKey(provider, model));
                 };
-                const deep = availableFor(assignments["deep-lo"]) !== undefined;
+                const deepLo = assignments["deep-lo"];
+                const deep =
+                    deepLo !== undefined &&
+                    assignments["deep-hi"] !== undefined &&
+                    availableFor(deepLo) !== undefined;
                 const candidates = workerNames.filter((name) => deep || !name.startsWith("deep-"));
-                const coordinate = assignments[deep ? "deep-lo" : "good-lo"];
+                const coordinate = deep ? deepLo : assignments["good-lo"];
                 workers = [coordinate, ...candidates.map((name) => assignments[name])].every(
-                    (assignment) => availableFor(assignment) !== undefined,
+                    (assignment) =>
+                        assignment !== undefined && availableFor(assignment) !== undefined,
                 )
                     ? candidates
                     : [];
@@ -222,7 +225,7 @@ const makeBasePlugin = (permissionsChanged: (permissions: Agent.Info["permission
                 for (const name of workers) active.add(name);
                 if (workers.length === 0) return;
                 for (const name of workers) {
-                    const assignment = assignments[name];
+                    const assignment = assignments[name]!;
                     const available = availableFor(assignment)!;
                     editor.update(name, (agent) => {
                         const hasVariant = available.model.variants.some(