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Enable/disable model configs and set the default atomically

Context and Problem Statement

Users want to remove a model from selection for a while, for example during a provider outage or while a quota is exhausted, without deleting it and losing its credentials and tuned params. The only way to hide a model was to delete it.

Setting the default model was not atomic either. The UI sent a full PUT /api/v1/models/[name] with the model's redacted params and is_default: true. That rewrote params, could trigger context-window discovery, and on other edits defaulted an omitted is_default to false, which silently unset the default.

Decision

  • Schema. Add model_configs.enabled INTEGER NOT NULL DEFAULT 1. Existing rows stay enabled. The additive migration lives in ensureModelConfigEnabledColumn in lib/db/migrations.ts.
  • State endpoint. PATCH /api/v1/models/[name] accepts { enabled?, is_default?: true }. Each change runs in a single transaction in lib/stores/model-config.ts and never touches params:
  • setDefaultModelConfig clears every other default and sets this one. A disabled model cannot become the default (409).
  • setModelConfigEnabled(false) clears the model's default flag and promotes the alphabetically first other enabled model. Disabling the last enabled model is rejected (409), so the workspace always has a runnable default.
  • Upserts preserve state. An omitted is_default keeps the existing flag, and enabled is always preserved. is_default: true on an upsert re-enables the row, so a default is never disabled.
  • Runtime resolution. getDefaultModelConfig, resolveRunnableModelConfig, the heuristic router candidates, thread model snapshots, and warm-summary jobs consider only enabled models. An agent explicitly bound to a disabled model keeps its binding but runs on routing or the default until the model is re-enabled. The client mirror is resolveAgentModel in lib/agents/effective-model.ts.
  • UI. The Models panel has a power toggle per model, dims disabled rows with a "disabled" badge, hides "Set as default" on them, and sets the default through PATCH. The agent model override picker lists only enabled models, plus the current selection marked "(disabled)".

Out of Scope

Secondary, explicitly configured model selections keep their current behavior and do not check enabled: the embedding model, citation checker, hallucination classifier model, pricing extraction, thread compaction, and dashboard metrics. These are opt-in settings that name a model directly. Disabling a model is about the chat model selection.

Consequences

  • Disabling is reversible and keeps credentials, params, and agent bindings.
  • Clients must handle 409 from PATCH (disabling the last enabled model, or defaulting a disabled one).
  • GET /api/v1/models rows gain enabled: boolean.