feat: remove auto model selection option (#1548)

* feat: remove auto model selection option

* set the default model if undefined

Author: ctlai95

chat-client/src/client/texts/modelSelection.ts

@@ -23,7 +23,8 @@ export const modelSelection: ChatItemFormItem = {
     type: 'select',
     id: 'model-selection',
     options: modelOptions,
-    placeholder: 'Auto',
+    mandatory: true,
+    hideMandatoryIcon: true,
     border: false,
     autoWidth: true,
 }
@@ -32,5 +33,5 @@ export const getModelSelectionChatItem = (modelId: string): ChatItem => ({
     type: ChatItemType.DIRECTIVE,
     contentHorizontalAlignment: 'center',
     fullWidth: true,
-    body: `Switched model to ${modelId === '' ? 'Auto' : modelRecord[modelId as BedrockModel].label}`,
+    body: `Switched model to ${modelRecord[modelId as BedrockModel].label}`,
 })

server/aws-lsp-codewhisperer/src/language-server/agenticChat/agenticChatController.test.ts

@@ -2479,6 +2479,32 @@ ${' '.repeat(8)}}
             })
         })
     })
+
+    describe('onPromptInputOptionChange', () => {
+        it('should set model ID from prompt input options', () => {
+            const mockTabId = 'tab-1'
+            const modelId = 'CLAUDE_3_7_SONNET_20250219_V1_0'
+            const setModelIdStub = sinon.stub(ChatDatabase.prototype, 'setModelId')
+
+            // Create a session
+            chatController.onTabAdd({ tabId: mockTabId })
+
+            // Call onPromptInputOptionChange with model selection
+            chatController.onPromptInputOptionChange({
+                tabId: mockTabId,
+                optionsValues: { 'model-selection': modelId },
+            })
+
+            // Verify the session has the model ID set
+            const session = chatSessionManagementService.getSession(mockTabId).data
+            assert.strictEqual(session!.modelId, modelId)
+
+            // Verify the model ID was saved to the database
+            sinon.assert.called(setModelIdStub)
+
+            setModelIdStub.restore()
+        })
+    })
 })
 
 // The body may include text-based progress updates from tool invocations.

server/aws-lsp-codewhisperer/src/language-server/agenticChat/agenticChatController.ts

@@ -119,6 +119,7 @@ import {
     outputLimitExceedsPartialMsg,
     responseTimeoutMs,
     responseTimeoutPartialMsg,
+    defaultModelId,
 } from './constants'
 import { URI } from 'vscode-uri'
 import { AgenticChatError, customerFacingErrorCodes, isRequestAbortedError, unactionableErrorCodes } from './errors'
@@ -2233,7 +2234,9 @@ export class AgenticChatController implements ChatHandlers {
     onTabAdd(params: TabAddParams) {
         this.#telemetryController.activeTabId = params.tabId
 
-        const modelId = this.#chatHistoryDb.getModelId()
+        // Since model selection is mandatory, the only time modelId is not set is when the chat history is empty.
+        // In that case, we use the default modelId.
+        const modelId = this.#chatHistoryDb.getModelId() ?? defaultModelId
         this.#features.chat.chatOptionsUpdate({ modelId: modelId, tabId: params.tabId })
 
         const sessionResult = this.#chatSessionManagementService.createSession(params.tabId)
@@ -2630,8 +2633,7 @@ export class AgenticChatController implements ChatHandlers {
         }
 
         session.pairProgrammingMode = params.optionsValues['pair-programmer-mode'] === 'true'
-        session.modelId =
-            params.optionsValues['model-selection'] === 'auto' ? undefined : params.optionsValues['model-selection']
+        session.modelId = params.optionsValues['model-selection']
 
         this.#chatHistoryDb.setModelId(session.modelId)
     }

server/aws-lsp-codewhisperer/src/language-server/agenticChat/constants.ts

@@ -5,3 +5,4 @@ export const outputLimitExceedsPartialMsg = 'output exceeds maximum character li
 export const responseTimeoutMs = 170_000
 export const responseTimeoutPartialMsg = 'Response processing timed out after'
 export const clientTimeoutMs = 180_000
+export const defaultModelId = 'CLAUDE_3_7_SONNET_20250219_V1_0' // TODO: this can't be imported from chat-client, so we hardcode it here