Deploying dee76b1 proved a raw durable append insufficient: the 07:54 dispatch recorded the wandering selection, yet the request assembled half a second later still carried the deepseek header, because prompt assembly reads the Session Controller's in-memory selection and the internal Agent controller caches one per Agent. Call its own selectForNextRequest primitive — append plus cache refresh, still without saving the deployment default — and fall back to the public selectModel if the surface moves. Fixture gains the Controller; two cases pin fast-path and fallback.
A role model only seeded brand-new Sessions, so Workers created before a settings change kept their old route forever — the operator's complaint that the default model 'did not take effect'. On dispatch, ensure() now compares the durable selection or header of an existing Session against the configured role model and appends a model/selection event when they drift, leaving the deployment default alone. Seven unit cases cover drift, idempotence, effort, and precedence.
wandering1
DeepSeek Harness Team