fix(app): use agent configured variant (#12993)

packages/app/src/context/model-variant.ts

@@ -0,0 +1,50 @@
+type AgentModel = {
+  providerID: string
+  modelID: string
+}
+
+type Agent = {
+  model?: AgentModel
+  variant?: string
+}
+
+type Model = AgentModel & {
+  variants?: Record<string, unknown>
+}
+
+type VariantInput = {
+  variants: string[]
+  selected: string | undefined
+  configured: string | undefined
+}
+
+export function getConfiguredAgentVariant(input: { agent: Agent | undefined; model: Model | undefined }) {
+  if (!input.agent?.variant) return undefined
+  if (!input.agent.model) return undefined
+  if (!input.model?.variants) return undefined
+  if (input.agent.model.providerID !== input.model.providerID) return undefined
+  if (input.agent.model.modelID !== input.model.modelID) return undefined
+  if (!(input.agent.variant in input.model.variants)) return undefined
+  return input.agent.variant
+}
+
+export function resolveModelVariant(input: VariantInput) {
+  if (input.selected && input.variants.includes(input.selected)) return input.selected
+  if (input.configured && input.variants.includes(input.configured)) return input.configured
+  return undefined
+}
+
+export function cycleModelVariant(input: VariantInput) {
+  if (input.variants.length === 0) return undefined
+  if (input.selected && input.variants.includes(input.selected)) {
+    const index = input.variants.indexOf(input.selected)
+    if (index === input.variants.length - 1) return undefined
+    return input.variants[index + 1]
+  }
+  if (input.configured && input.variants.includes(input.configured)) {
+    const index = input.variants.indexOf(input.configured)
+    if (index === input.variants.length - 1) return input.variants[0]
+    return input.variants[index + 1]
+  }
+  return input.variants[0]
+}