fix(plugin): migrate chat.params to maxOutputTokens for v1.4.0

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/plugin/chat-params.test.ts

@@ -123,10 +123,10 @@ describe("createChatParamsHandler", () => {
     setSessionPromptParams("ses_chat_params_temperature", {
       temperature: 0.4,
       topP: 0.7,
+      maxOutputTokens: 4096,
       options: {
         reasoningEffort: "high",
         thinking: { type: "disabled" },
-        maxTokens: 4096,
       },
     })
 
@@ -157,31 +157,29 @@ describe("createChatParamsHandler", () => {
       temperature: 0.4,
       topP: 0.7,
       topK: 1,
+      maxOutputTokens: 4096,
       options: {
         existing: true,
         reasoningEffort: "high",
         thinking: { type: "disabled" },
-        maxTokens: 4096,
       },
     })
     expect(getSessionPromptParams("ses_chat_params_temperature")).toEqual({
       temperature: 0.4,
       topP: 0.7,
+      maxOutputTokens: 4096,
       options: {
         reasoningEffort: "high",
         thinking: { type: "disabled" },
-        maxTokens: 4096,
       },
     })
   })
 
-  test("drops gpt-5.4 temperature and clamps maxTokens from bundled model capabilities", async () => {
+  test("drops gpt-5.4 temperature and clamps maxOutputTokens from bundled model capabilities", async () => {
     //#given
     setSessionPromptParams("ses_chat_params_temperature", {
       temperature: 0.7,
-      options: {
-        maxTokens: 200_000,
-      },
+      maxOutputTokens: 200_000,
     })
 
     const handler = createChatParamsHandler({
@@ -210,9 +208,8 @@ describe("createChatParamsHandler", () => {
     expect(output).toEqual({
       topP: 1,
       topK: 1,
-      options: {
-        maxTokens: 128_000,
-      },
+      maxOutputTokens: 128_000,
+      options: {},
     })
   })
 

src/plugin/chat-params.ts

@@ -18,6 +18,7 @@ export type ChatParamsOutput = {
   temperature?: number
   topP?: number
   topK?: number
+  maxOutputTokens?: number
   options: Record<string, unknown>
 }
 
@@ -99,6 +100,9 @@ export function createChatParamsHandler(args: {
       if (storedPromptParams.topP !== undefined) {
         output.topP = storedPromptParams.topP
       }
+      if (storedPromptParams.maxOutputTokens !== undefined) {
+        output.maxOutputTokens = storedPromptParams.maxOutputTokens
+      }
       if (storedPromptParams.options) {
         output.options = {
           ...output.options,
@@ -124,7 +128,7 @@ export function createChatParamsHandler(args: {
           : undefined,
         temperature: typeof output.temperature === "number" ? output.temperature : undefined,
         topP: typeof output.topP === "number" ? output.topP : undefined,
-        maxTokens: typeof output.options.maxTokens === "number" ? output.options.maxTokens : undefined,
+        maxTokens: typeof output.maxOutputTokens === "number" ? output.maxOutputTokens : undefined,
         thinking: isRecord(output.options.thinking) ? output.options.thinking : undefined,
       },
       capabilities,
@@ -163,9 +167,9 @@ export function createChatParamsHandler(args: {
 
     if ("maxTokens" in compatibility) {
       if (compatibility.maxTokens !== undefined) {
-        output.options.maxTokens = compatibility.maxTokens
+        output.maxOutputTokens = compatibility.maxTokens
       } else {
-        delete output.options.maxTokens
+        delete output.maxOutputTokens
       }
     }
 

src/shared/session-prompt-params-state.ts

@@ -1,6 +1,7 @@
 export type SessionPromptParams = {
   temperature?: number
   topP?: number
+  maxOutputTokens?: number
   options?: Record<string, unknown>
 }
 
@@ -10,6 +11,7 @@ export function setSessionPromptParams(sessionID: string, params: SessionPromptP
   sessionPromptParams.set(sessionID, {
     ...(params.temperature !== undefined ? { temperature: params.temperature } : {}),
     ...(params.topP !== undefined ? { topP: params.topP } : {}),
+    ...(params.maxOutputTokens !== undefined ? { maxOutputTokens: params.maxOutputTokens } : {}),
     ...(params.options !== undefined ? { options: { ...params.options } } : {}),
   })
 }
@@ -21,6 +23,7 @@ export function getSessionPromptParams(sessionID: string): SessionPromptParams |
   return {
     ...(params.temperature !== undefined ? { temperature: params.temperature } : {}),
     ...(params.topP !== undefined ? { topP: params.topP } : {}),
+    ...(params.maxOutputTokens !== undefined ? { maxOutputTokens: params.maxOutputTokens } : {}),
     ...(params.options !== undefined ? { options: { ...params.options } } : {}),
   }
 }