fix(server): surface Cursor Auto Optimize For modes

apps/server/src/provider/Layers/CursorProvider.test.ts

@@ -299,6 +299,29 @@ const parameterizedClaudeModelOptionConfigOptions = [
   },
 ] satisfies ReadonlyArray<EffectAcpSchema.SessionConfigOption>;
 
+const parameterizedAutoSmartConfigOptions = [
+  {
+    type: "select",
+    currentValue: "auto-smart",
+    options: [{ name: "Auto", value: "auto-smart" }],
+    category: "model",
+    id: "model",
+    name: "Model",
+  },
+  {
+    type: "select",
+    currentValue: "balanced",
+    options: [
+      { name: "Intelligence", value: "intelligence" },
+      { name: "Balance", value: "balanced" },
+      { name: "Cost", value: "cost" },
+    ],
+    category: "model_config",
+    id: "optimize_for",
+    name: "Optimize For",
+  },
+] satisfies ReadonlyArray<EffectAcpSchema.SessionConfigOption>;
+
 const baseCursorSettings: CursorSettings = {
   enabled: true,
   binaryPath: "cursor-agent",
@@ -523,6 +546,20 @@ describe("buildCursorCapabilitiesFromConfigOptions", () => {
       }),
     );
   });
+
+  it("derives Optimize For modes for Cursor Router Auto", () => {
+    expect(buildCursorCapabilitiesFromConfigOptions(parameterizedAutoSmartConfigOptions)).toEqual(
+      createModelCapabilities({
+        optionDescriptors: [
+          selectDescriptor("optimizeFor", "Optimize For", [
+            { id: "intelligence", label: "Intelligence" },
+            { id: "balanced", label: "Balance", isDefault: true },
+            { id: "cost", label: "Cost" },
+          ]),
+        ],
+      }),
+    );
+  });
 });
 
 describe("checkCursorProviderStatus", () => {
@@ -775,4 +812,12 @@ describe("resolveCursorAcpConfigUpdates", () => {
       { configId: "thinking", value: "false" },
     ]);
   });
+
+  it("writes Cursor Router Optimize For Cost through optimize_for", () => {
+    expect(
+      resolveCursorAcpConfigUpdates(parameterizedAutoSmartConfigOptions, [
+        { id: "optimizeFor", value: "cost" },
+      ]),
+    ).toEqual([{ configId: "optimize_for", value: "cost" }]);
+  });
 });

apps/server/src/provider/Layers/CursorProvider.ts

@@ -197,6 +197,23 @@ function findCursorEffortConfigOption(
   );
 }
 
+function isCursorOptimizeForConfigOption(option: EffectAcpSchema.SessionConfigOption): boolean {
+  const id = option.id.trim().toLowerCase();
+  const name = option.name.trim().toLowerCase();
+  return id === "optimize_for" || name.includes("optimize");
+}
+
+function findCursorOptimizeForConfigOption(
+  configOptions: ReadonlyArray<EffectAcpSchema.SessionConfigOption>,
+): EffectAcpSchema.SessionConfigOption | undefined {
+  return configOptions.find(
+    (option) =>
+      option.type === "select" &&
+      getCursorConfigOptionCategory(option) === "model_config" &&
+      isCursorOptimizeForConfigOption(option),
+  );
+}
+
 function isCursorContextConfigOption(option: EffectAcpSchema.SessionConfigOption): boolean {
   const id = option.id.trim().toLowerCase();
   const name = option.name.trim().toLowerCase();
@@ -257,6 +274,24 @@ export function buildCursorCapabilitiesFromConfigOptions(
     return EMPTY_CAPABILITIES;
   }
 
+  const optimizeForOption = findCursorOptimizeForConfigOption(configOptions);
+  const optimizeForOptions =
+    optimizeForOption?.type === "select"
+      ? flattenSessionConfigSelectOptions(optimizeForOption).map((entry) => {
+          if (optimizeForOption.currentValue === entry.value) {
+            return {
+              value: entry.value,
+              label: entry.name,
+              isDefault: true,
+            };
+          }
+          return {
+            value: entry.value,
+            label: entry.name,
+          };
+        })
+      : [];
+
   const reasoningConfig = findCursorEffortConfigOption(configOptions);
   const reasoningEffortLevels =
     reasoningConfig?.type === "select"
@@ -306,6 +341,15 @@ export function buildCursorCapabilitiesFromConfigOptions(
   const fastCurrentValue = getBooleanCurrentValue(fastOption);
   const thinkingCurrentValue = getBooleanCurrentValue(thinkingOption);
   const optionDescriptors = [
+    ...(optimizeForOptions.length > 0
+      ? [
+          buildSelectOptionDescriptor({
+            id: "optimizeFor",
+            label: optimizeForOption?.name?.trim() || "Optimize For",
+            options: optimizeForOptions,
+          }),
+        ]
+      : []),
     ...(reasoningEffortLevels.length > 0
       ? [
           buildSelectOptionDescriptor({
@@ -493,6 +537,22 @@ export function resolveCursorAcpConfigUpdates(
     readonly value: string | boolean;
   }> = [];
 
+  const optimizeForOption = findCursorOptimizeForConfigOption(configOptions);
+  const requestedOptimizeFor = getProviderOptionStringSelectionValue(selections, "optimizeFor");
+  if (optimizeForOption && requestedOptimizeFor) {
+    const value = findCursorSelectOptionValue(
+      optimizeForOption,
+      (option) =>
+        normalizeCursorConfigOptionToken(option.value) ===
+          normalizeCursorConfigOptionToken(requestedOptimizeFor) ||
+        normalizeCursorConfigOptionToken(option.name) ===
+          normalizeCursorConfigOptionToken(requestedOptimizeFor),
+    );
+    if (value) {
+      updates.push({ configId: optimizeForOption.id, value });
+    }
+  }
+
   const reasoningOption = findCursorEffortConfigOption(configOptions);
   const requestedReasoning = normalizeCursorReasoningValue(
     getProviderOptionStringSelectionValue(selections, "reasoning"),

apps/web/src/components/settings/ProviderModelsSection.tsx

@@ -57,6 +57,7 @@ function describeModelCapabilities(model: ServerProviderModel): string[] {
         (descriptor.id === "reasoningEffort" ||
           descriptor.id === "effort" ||
           descriptor.id === "reasoning" ||
+          descriptor.id === "optimizeFor" ||
           descriptor.id === "variant"),
     )
   ) {