test: remove if conditional and add test to verify Mistral no-user-after-tool constraint

src/api/providers/__tests__/openai.spec.ts

@@ -1201,14 +1201,78 @@ describe("OpenAiHandler", () => {
 			// This is the key verification that mergeToolResultText is working correctly
 			expect(toolMessage.content).toContain("File content here")
 			expect(toolMessage.content).toContain("environment_details")
+		})
 
-			// Verify there is NO user message immediately after the tool message
+		it("should not have user message after tool message for Mistral models", async () => {
+			// Create a message sequence that includes a follow-up after the tool result
+			// to verify the Mistral constraint is enforced
+			const messagesWithFollowUp: Anthropic.Messages.MessageParam[] = [
+				{
+					role: "user",
+					content: [{ type: "text", text: "Read test.ts and explain it" }],
+				},
+				{
+					role: "assistant",
+					content: [
+						{
+							type: "tool_use",
+							id: "call_abc123xyz",
+							name: "read_file",
+							input: { path: "test.ts" },
+						},
+					],
+				},
+				{
+					role: "user",
+					content: [
+						{
+							type: "tool_result",
+							tool_use_id: "call_abc123xyz",
+							content: "export const foo = 'bar'",
+						},
+						{
+							type: "text",
+							text: "<environment_details>Current directory: /project</environment_details>",
+						},
+					],
+				},
+				{
+					role: "assistant",
+					content: [{ type: "text", text: "This file exports a constant named foo with value 'bar'." }],
+				},
+				{
+					role: "user",
+					content: [{ type: "text", text: "Thanks!" }],
+				},
+			]
+
+			const mistralHandler = new OpenAiHandler({
+				...mockOptions,
+				openAiModelId: "mistral-large-latest",
+			})
+
+			const stream = mistralHandler.createMessage(systemPrompt, messagesWithFollowUp)
+			for await (const _chunk of stream) {
+				// Consume the stream
+			}
+
+			expect(mockCreate).toHaveBeenCalled()
+			const callArgs = mockCreate.mock.calls[0][0]
+			const messages = callArgs.messages
+
+			// Find the tool message
+			const toolMessageIndex = messages.findIndex((m: any) => m.role === "tool")
+			expect(toolMessageIndex).not.toBe(-1)
+
+			// Verify there IS a next message (the assistant response)
+			const nextMessage = messages[toolMessageIndex + 1]
+			expect(nextMessage).toBeDefined()
+
+			// Verify the next message is NOT a user message
 			// This is the Mistral constraint: after tool, only assistant or tool is allowed, never user
 			// Per mistral_common validator: elif previous_role == Roles.tool: expected_roles = {Roles.assistant, Roles.tool}
-			const nextMessage = messages[toolMessageIndex + 1]
-			if (nextMessage) {
-				expect(nextMessage.role).not.toBe("user")
-			}
+			expect(nextMessage.role).not.toBe("user")
+			expect(nextMessage.role).toBe("assistant")
 		})
 
 		it("should detect Devstral models and apply mergeToolResultText", async () => {