Thanks — engagement-level model overrides and the Mittwald route are both wanted. This needs a rebase + cleanup before it can land, though:

1. Conflicts with main / overlaps already-merged work. Since this PR was opened, per-role model override landed via the existing model_override middleware (feat(llm): modular per-role model override + MID→Sonnet 5 #762) and per-role composition via PluginBundle.models + env (feat(llm): compose per-role model via PluginBundle.models + env override #767). This PR also adds middleware/model_override.py and edits middleware_slots.py, so it now conflicts and partly duplicates what's on main. Please rebase onto current main and reconcile against the merged middleware rather than reintroducing a parallel path.
2. Duplicate Prisma migration. There are two migrations for the same feature — 20260708120000_add_engagement_model_override and 20260708153000_add_engagement_model_overrides. Collapse to one.
3. Please split the transport/egress bits out. The Mittwald LiteLLM route (litellm_dynamic_config.py, .env.example) and the Mullvad egress work (docker-compose.mullvad.yml, docker-compose.lan.yml, docs/ops/mullvad-sandbox-egress.md) are unrelated to the model-override UI and touch CODEOWNERS-protected compose files. Landing them as their own small PR will get each through review much faster.
4. No CI has run on this branch yet — once rebased, please confirm make quality + the web lane are green locally (this touches clients/web schema + API routes).

Leaving open for the rebase. Ping me when it's split and green and I'll review promptly.