fix provider switch not presistingin session (#903)

* fix provider switch not presistingin session

* fix broken tests

src/constants/promptIdentity.test.ts

@@ -11,6 +11,7 @@ import { afterEach, expect, test } from 'bun:test'
   NATIVE_PACKAGE_URL: undefined,
 }
 
+import { clearSystemPromptSections } from './systemPromptSections.js'
 import { getSystemPrompt, DEFAULT_AGENT_PROMPT } from './prompts.js'
 import { CLI_SYSPROMPT_PREFIXES, getCLISyspromptPrefix } from './system.js'
 import { CLAUDE_CODE_GUIDE_AGENT } from '../tools/AgentTool/built-in/claudeCodeGuideAgent.js'
@@ -23,6 +24,7 @@ const originalSimpleEnv = process.env.CLAUDE_CODE_SIMPLE
 
 afterEach(() => {
   process.env.CLAUDE_CODE_SIMPLE = originalSimpleEnv
+  clearSystemPromptSections()
 })
 
 test('CLI identity prefixes describe OpenClaude instead of Claude Code', () => {
@@ -47,6 +49,21 @@ test('simple mode identity describes OpenClaude instead of Claude Code', async (
   expect(prompt[0]).not.toContain("Anthropic's official CLI for Claude")
 })
 
+test('system prompt model identity updates when model changes mid-session', async () => {
+  delete process.env.CLAUDE_CODE_SIMPLE
+  clearSystemPromptSections()
+
+  const firstPrompt = await getSystemPrompt([], 'old-test-model')
+  const secondPrompt = await getSystemPrompt([], 'new-test-model')
+
+  const firstText = firstPrompt.join('\n')
+  const secondText = secondPrompt.join('\n')
+
+  expect(firstText).toContain('You are powered by the model old-test-model.')
+  expect(secondText).toContain('You are powered by the model new-test-model.')
+  expect(secondText).not.toContain('You are powered by the model old-test-model.')
+})
+
 test('built-in agent prompts describe OpenClaude instead of Claude Code', () => {
   expect(DEFAULT_AGENT_PROMPT).toContain('OpenClaude')
   expect(DEFAULT_AGENT_PROMPT).not.toContain('Claude Code')

src/constants/prompts.ts

@@ -496,7 +496,7 @@ ${CYBER_RISK_INSTRUCTION}`,
     systemPromptSection('ant_model_override', () =>
       getAntModelOverrideSection(),
     ),
-    systemPromptSection('env_info_simple', () =>
+    systemPromptSection(`env_info_simple:${model}`, () =>
       computeSimpleEnvInfo(model, additionalWorkingDirectories),
     ),
     systemPromptSection('language', () =>
@@ -519,7 +519,7 @@ ${CYBER_RISK_INSTRUCTION}`,
       'MCP servers connect/disconnect between turns',
     ),
     systemPromptSection('scratchpad', () => getScratchpadInstructions()),
-    systemPromptSection('frc', () => getFunctionResultClearingSection(model)),
+    systemPromptSection(`frc:${model}`, () => getFunctionResultClearingSection(model)),
     systemPromptSection(
       'summarize_tool_results',
       () => SUMMARIZE_TOOL_RESULTS_SECTION,