hermes - 💡(How to fix) Fix [Bug]: Gateway /model without --global does not persist, leaves remote users stuck with stale defaults

Bug Description

When using Hermes through a messaging gateway (Feishu, Telegram, Discord, etc.), running /model deepseek-v4-pro successfully switches the model for the current session, but does not persist the change to ~/.hermes/config.yaml. After hermes gateway restart, the model reverts to the old model.default.

This is especially problematic for remote/gateway users who:

• Don't have terminal access at that moment
• Can't run hermes model or hermes config set
• Expect /model to behave like a remote model management command

Root Cause

gateway/run.py line ~10149:

# Persist to config if --global
if persist_global:
    # ... writes to config.yaml

Without --global, the switch is stored only as _session_model_overrides[session_key] (ephemeral), and never written to config.yaml.

Steps to Reproduce

1. Run Hermes gateway connected to Feishu
2. In Feishu, execute /model deepseek-v4-pro
3. Wait for confirmation ("Switched to deepseek-v4-pro")
4. Run hermes gateway restart
5. Check model.default in config.yaml — still shows the old model

Expected Behavior

Gateway /model without --global should either:

• Option A: Default to persisting the change (since remote users cannot easily access config.yaml), matching the CLI behavior of hermes model
• Option B: Clearly communicate that the switch is session-only and suggest /model --global for persistent changes

Actual Behavior

The switch silently applies only to the current session. After a gateway restart, the old model returns with no warning.

Environment

• Hermes Agent version: latest (git-installed)
• Platform: macOS 26.5 + Feishu
• The user discovered this after a gateway restart reverted DeepSeek V4 Pro back to GLM-5.1, and GLM-5.1's API was out of balance (HTTP 429), causing the agent to become unresponsive for several minutes.

Related Issues

• #25107 — Gateway /model switch leaves stale base_url and does not persist api_mode (even with --global, persistence is incomplete)
• #28034 — /model --global does not persist when using the visual model picker (CLI-specific)

Suggested Fix

Either make /model always persist in gateway context (since the user is remote), or add a note in the confirmation message like:

Switched to deepseek-v4-pro (session only — use `/model --global` to make it permanent)