diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index 3bad8cc..baa9f4f 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -26,10 +26,11 @@ model Experiment {
 }
 
 model PromptVariant {
-    id    String @id @default(uuid()) @db.Uuid
-    label String
+    id String @id @default(uuid()) @db.Uuid
 
+    label       String
     constructFn String
+    model       String @default("gpt-3.5-turbo")
 
     uiId      String  @default(uuid()) @db.Uuid
     visible   Boolean @default(true)
diff --git a/src/components/OutputsTable/OutputCell/OutputCell.tsx b/src/components/OutputsTable/OutputCell/OutputCell.tsx
index 6f0f615..8307852 100644
--- a/src/components/OutputsTable/OutputCell/OutputCell.tsx
+++ b/src/components/OutputsTable/OutputCell/OutputCell.tsx
@@ -37,10 +37,6 @@ export default function OutputCell({
   // if (variant.config === null || Object.keys(variant.config).length === 0)
   //   disabledReason = "Save your prompt variant to see output";
 
-  // const model = getModelName(variant.config as JSONSerializable);
-  // TODO: Temporarily hardcoding this while we get other stuff working
-  const model = "gpt-3.5-turbo";
-
   const outputMutation = api.outputs.get.useMutation();
 
   const [output, setOutput] = useState<RouterOutputs["outputs"]["get"]>(null);
@@ -140,7 +136,7 @@ export default function OutputCell({
             { maxLength: 40 },
           )}
         </SyntaxHighlighter>
-        <OutputStats model={model} modelOutput={output} scenario={scenario} />
+        <OutputStats model={variant.model} modelOutput={output} scenario={scenario} />
       </Box>
     );
   }
@@ -150,7 +146,7 @@ export default function OutputCell({
   return (
     <Flex w="100%" h="100%" direction="column" justifyContent="space-between" whiteSpace="pre-wrap">
       {contentToDisplay}
-      {output && <OutputStats model={model} modelOutput={output} scenario={scenario} />}
+      {output && <OutputStats model={variant.model} modelOutput={output} scenario={scenario} />}
     </Flex>
   );
 }
diff --git a/src/components/OutputsTable/OutputCell/OutputStats.tsx b/src/components/OutputsTable/OutputCell/OutputStats.tsx
index 4491300..02e5780 100644
--- a/src/components/OutputsTable/OutputCell/OutputStats.tsx
+++ b/src/components/OutputsTable/OutputCell/OutputStats.tsx
@@ -17,7 +17,7 @@ export const OutputStats = ({
   modelOutput,
   scenario,
 }: {
-  model: SupportedModel | null;
+  model: SupportedModel | string | null;
   modelOutput: ModelOutput;
   scenario: Scenario;
 }) => {
diff --git a/src/components/OutputsTable/VariantEditor.tsx b/src/components/OutputsTable/VariantEditor.tsx
index d1eb1ce..526bed0 100644
--- a/src/components/OutputsTable/VariantEditor.tsx
+++ b/src/components/OutputsTable/VariantEditor.tsx
@@ -59,10 +59,17 @@ export default function VariantConfigEditor(props: { variant: PromptVariant }) {
       return;
     }
 
-    await replaceVariant.mutateAsync({
+    const resp = await replaceVariant.mutateAsync({
       id: props.variant.id,
       constructFn: currentFn,
     });
+    if (resp.status === "error") {
+      return toast({
+        title: "Error saving variant",
+        description: resp.message,
+        status: "error",
+      });
+    }
 
     await utils.promptVariants.list.invalidate();
 
diff --git a/src/server/api/routers/experiments.router.ts b/src/server/api/routers/experiments.router.ts
index 21e6b52..1c47d7a 100644
--- a/src/server/api/routers/experiments.router.ts
+++ b/src/server/api/routers/experiments.router.ts
@@ -75,6 +75,7 @@ export const experimentsRouter = createTRPCRouter({
             stream: true,
             messages: [{ role: "system", content: "Return 'Ready to go!'" }],
           }`,
+          model: "gpt-3.5-turbo-0613",
         },
       }),
       prisma.testScenario.create({
diff --git a/src/server/api/routers/modelOutputs.router.ts b/src/server/api/routers/modelOutputs.router.ts
index 848305d..7b11850 100644
--- a/src/server/api/routers/modelOutputs.router.ts
+++ b/src/server/api/routers/modelOutputs.router.ts
@@ -6,6 +6,7 @@ import type { Prisma } from "@prisma/client";
 import { reevaluateVariant } from "~/server/utils/evaluations";
 import { getCompletion } from "~/server/utils/getCompletion";
 import { constructPrompt } from "~/server/utils/constructPrompt";
+import { type CompletionCreateParams } from "openai/resources/chat";
 
 export const modelOutputsRouter = createTRPCRouter({
   get: publicProcedure
@@ -43,7 +44,7 @@ export const modelOutputsRouter = createTRPCRouter({
 
       if (!variant || !scenario) return null;
 
-      const prompt = await constructPrompt(variant, scenario);
+      const prompt = await constructPrompt(variant, scenario.variableValues);
 
       const inputHash = crypto.createHash("sha256").update(JSON.stringify(prompt)).digest("hex");
 
@@ -65,7 +66,10 @@ export const modelOutputsRouter = createTRPCRouter({
         };
       } else {
         try {
-          modelResponse = await getCompletion(prompt, input.channel);
+          modelResponse = await getCompletion(
+            prompt as unknown as CompletionCreateParams,
+            input.channel,
+          );
         } catch (e) {
           console.error(e);
           throw e;
diff --git a/src/server/api/routers/promptVariants.router.ts b/src/server/api/routers/promptVariants.router.ts
index 6e10ea6..943c4c1 100644
--- a/src/server/api/routers/promptVariants.router.ts
+++ b/src/server/api/routers/promptVariants.router.ts
@@ -1,6 +1,10 @@
+import { isObject } from "lodash";
 import { z } from "zod";
 import { createTRPCRouter, publicProcedure } from "~/server/api/trpc";
 import { prisma } from "~/server/db";
+import { OpenAIChatModel } from "~/server/types";
+import { constructPrompt } from "~/server/utils/constructPrompt";
+import userError from "~/server/utils/error";
 import { recordExperimentUpdated } from "~/server/utils/recordExperimentUpdated";
 import { calculateTokenCost } from "~/utils/calculateTokenCost";
 
@@ -57,14 +61,10 @@ export const promptVariantsRouter = createTRPCRouter({
       },
     });
 
-    // TODO: fix this
-    const model = "gpt-3.5-turbo-0613";
-    // const model = getModelName(variant.config);
-
     const promptTokens = overallTokens._sum?.promptTokens ?? 0;
-    const overallPromptCost = calculateTokenCost(model, promptTokens);
+    const overallPromptCost = calculateTokenCost(variant.model, promptTokens);
     const completionTokens = overallTokens._sum?.completionTokens ?? 0;
-    const overallCompletionCost = calculateTokenCost(model, completionTokens, true);
+    const overallCompletionCost = calculateTokenCost(variant.model, completionTokens, true);
 
     const overallCost = overallPromptCost + overallCompletionCost;
 
@@ -106,6 +106,7 @@ export const promptVariantsRouter = createTRPCRouter({
           label: `Prompt Variant ${largestSortIndex + 2}`,
           sortIndex: (lastVariant?.sortIndex ?? 0) + 1,
           constructFn: lastVariant?.constructFn ?? "",
+          model: lastVariant?.model ?? "gpt-3.5-turbo",
         },
       });
 
@@ -185,6 +186,27 @@ export const promptVariantsRouter = createTRPCRouter({
         throw new Error(`Prompt Variant with id ${input.id} does not exist`);
       }
 
+      let model = existing.model;
+      try {
+        const contructedPrompt = await constructPrompt({ constructFn: input.constructFn }, null);
+
+        if (!isObject(contructedPrompt)) {
+          return userError("Prompt is not an object");
+        }
+        if (!("model" in contructedPrompt)) {
+          return userError("Prompt does not define a model");
+        }
+        if (
+          typeof contructedPrompt.model !== "string" ||
+          !(contructedPrompt.model in OpenAIChatModel)
+        ) {
+          return userError("Prompt defines an invalid model");
+        }
+        model = contructedPrompt.model;
+      } catch (e) {
+        return userError((e as Error).message);
+      }
+
       // Create a duplicate with only the config changed
       const newVariant = await prisma.promptVariant.create({
         data: {
@@ -193,11 +215,12 @@ export const promptVariantsRouter = createTRPCRouter({
           sortIndex: existing.sortIndex,
           uiId: existing.uiId,
           constructFn: input.constructFn,
+          model,
         },
       });
 
       // Hide anything with the same uiId besides the new one
-      const hideOldVariantsAction = prisma.promptVariant.updateMany({
+      const hideOldVariants = prisma.promptVariant.updateMany({
         where: {
           uiId: existing.uiId,
           id: {
@@ -209,12 +232,9 @@ export const promptVariantsRouter = createTRPCRouter({
         },
       });
 
-      await prisma.$transaction([
-        hideOldVariantsAction,
-        recordExperimentUpdated(existing.experimentId),
-      ]);
+      await prisma.$transaction([hideOldVariants, recordExperimentUpdated(existing.experimentId)]);
 
-      return newVariant;
+      return { status: "ok" } as const;
     }),
 
   reorder: publicProcedure
diff --git a/src/server/utils/constructPrompt.test.ts b/src/server/utils/constructPrompt.test.ts
index 78c485f..d0c98ff 100644
--- a/src/server/utils/constructPrompt.test.ts
+++ b/src/server/utils/constructPrompt.test.ts
@@ -7,9 +7,7 @@ test.skip("constructPrompt", async () => {
       constructFn: `prompt = { "fooz": "bar" }`,
     },
     {
-      variableValues: {
-        foo: "bar",
-      },
+      foo: "bar",
     },
   );
 
diff --git a/src/server/utils/constructPrompt.ts b/src/server/utils/constructPrompt.ts
index 30eb5e6..3b7c283 100644
--- a/src/server/utils/constructPrompt.ts
+++ b/src/server/utils/constructPrompt.ts
@@ -6,10 +6,8 @@ const isolate = new ivm.Isolate({ memoryLimit: 128 });
 
 export async function constructPrompt(
   variant: Pick<PromptVariant, "constructFn">,
-  testScenario: Pick<TestScenario, "variableValues">,
+  scenario: TestScenario["variableValues"],
 ): Promise<JSONSerializable> {
-  const scenario = testScenario.variableValues as JSONSerializable;
-
   const code = `
       const scenario = ${JSON.stringify(scenario, null, 2)};
       let prompt
diff --git a/src/server/utils/error.ts b/src/server/utils/error.ts
new file mode 100644
index 0000000..f284a8d
--- /dev/null
+++ b/src/server/utils/error.ts
@@ -0,0 +1,6 @@
+export default function userError(message: string): { status: "error"; message: string } {
+  return {
+    status: "error",
+    message,
+  };
+}
diff --git a/src/server/utils/getCompletion.ts b/src/server/utils/getCompletion.ts
index e7b33a2..61452e4 100644
--- a/src/server/utils/getCompletion.ts
+++ b/src/server/utils/getCompletion.ts
@@ -4,14 +4,11 @@ import { Prisma } from "@prisma/client";
 import { streamChatCompletion } from "./openai";
 import { wsConnection } from "~/utils/wsConnection";
 import { type ChatCompletion, type CompletionCreateParams } from "openai/resources/chat";
-import { type JSONSerializable, OpenAIChatModel } from "../types";
+import { type OpenAIChatModel } from "../types";
 import { env } from "~/env.mjs";
 import { countOpenAIChatTokens } from "~/utils/countTokens";
-import { getModelName } from "./getModelName";
 import { rateLimitErrorMessage } from "~/sharedStrings";
 
-env;
-
 type CompletionResponse = {
   output: Prisma.InputJsonValue | typeof Prisma.JsonNull;
   statusCode: number;
@@ -22,35 +19,7 @@ type CompletionResponse = {
 };
 
 export async function getCompletion(
-  payload: JSONSerializable,
-  channel?: string,
-): Promise<CompletionResponse> {
-  const modelName = getModelName(payload);
-  if (!modelName)
-    return {
-      output: Prisma.JsonNull,
-      statusCode: 400,
-      errorMessage: "Invalid payload provided",
-      timeToComplete: 0,
-    };
-  if (modelName in OpenAIChatModel) {
-    return getOpenAIChatCompletion(
-      payload as unknown as CompletionCreateParams,
-      env.OPENAI_API_KEY,
-      channel,
-    );
-  }
-  return {
-    output: Prisma.JsonNull,
-    statusCode: 400,
-    errorMessage: "Invalid model provided",
-    timeToComplete: 0,
-  };
-}
-
-export async function getOpenAIChatCompletion(
   payload: CompletionCreateParams,
-  apiKey: string,
   channel?: string,
 ): Promise<CompletionResponse> {
   // If functions are enabled, disable streaming so that we get the full response with token counts
@@ -60,7 +29,7 @@ export async function getOpenAIChatCompletion(
     method: "POST",
     headers: {
       "Content-Type": "application/json",
-      Authorization: `Bearer ${apiKey}`,
+      Authorization: `Bearer ${env.OPENAI_API_KEY}`,
     },
     body: JSON.stringify(payload),
   });
diff --git a/src/server/utils/getModelName.ts b/src/server/utils/getModelName.ts
deleted file mode 100644
index 4fcaef1..0000000
--- a/src/server/utils/getModelName.ts
+++ /dev/null
@@ -1,9 +0,0 @@
-import { isObject } from "lodash";
-import { type JSONSerializable, type SupportedModel } from "../types";
-import { type Prisma } from "@prisma/client";
-
-export function getModelName(config: JSONSerializable | Prisma.JsonValue): SupportedModel | null {
-  if (!isObject(config)) return null;
-  if ("model" in config && typeof config.model === "string") return config.model as SupportedModel;
-  return null;
-}
diff --git a/src/state/sharedVariantEditor.slice.ts b/src/state/sharedVariantEditor.slice.ts
index ce455db..d6d8bd8 100644
--- a/src/state/sharedVariantEditor.slice.ts
+++ b/src/state/sharedVariantEditor.slice.ts
@@ -14,6 +14,9 @@ export type SharedVariantEditorSlice = {
 export const createVariantEditorSlice: SliceCreator<SharedVariantEditorSlice> = (set, get) => ({
   monaco: loader.__getMonacoInstance(),
   loadMonaco: async () => {
+    // We only want to run this client-side
+    if (typeof window === "undefined") return;
+
     const monaco = await loader.init();
 
     monaco.editor.defineTheme("customTheme", {
diff --git a/src/utils/calculateTokenCost.ts b/src/utils/calculateTokenCost.ts
index a64a289..56c6f0a 100644
--- a/src/utils/calculateTokenCost.ts
+++ b/src/utils/calculateTokenCost.ts
@@ -23,7 +23,7 @@ const openAICompletionTokensToDollars: { [key in OpenAIChatModel]: number } = {
 };
 
 export const calculateTokenCost = (
-  model: SupportedModel | null,
+  model: SupportedModel | string | null,
   numTokens: number,
   isCompletion = false,
 ) => {