[BUG] /model setting does not persist across sessions despite “future sessions” claim

Describe the bug

The /model command is supposed to persist the selected model across sessions. As per the description shown in the Claude Code interface:

"Applies to this session and future Claude Code sessions."

However, this does not seem to be the case. After setting the model to claude-3-sonnet (or any other Claude 4.x variant), the setting reverts back to claude-3-7-sonnet every time the environment is restarted.

Steps to reproduce

1. Run /model claude-3-sonnet (or another supported model)
2. Confirm that the model is switched correctly in the current session
3. Restart the Claude Code environment (e.g., reload the IDE or reopen the session)
4. Check the active model again with /model
5. Notice it has reverted back to claude-3-7-sonnet

Expected behavior

The selected model should persist across sessions, as the message suggests.

Actual behavior

The model selection is reset to claude-3-7-sonnet on every restart, making it necessary to manually reapply the /model command each time.

Environment

• Claude Code version: 1.0.9 with Bedrock API Key
• Editor: ITerm2 Build 3.5.14
• OS: macOS 15.5（24F74）

Additional context

This behavior causes confusion and unintended use of an older model version. The expectation set by the documentation is not currently met.