# Agent Note: Declaring a provider from the Models page

Status: implemented

English | [中文](2026-08-04-declaring-a-provider-from-the-models-page.zh.md)

## Problem

The two layers below made a pi-ai route [a declaration](2026-08-03-pi-ai-declared-provider-catalog.md) and gave the host a way to [interrogate a draft endpoint](2026-08-04-draft-provider-endpoint-interrogation.md). Neither reached a person who does not edit YAML: the Models page still offered one API-key field per provider and a fold with a base URL, so adding a gateway meant opening `$DSH_HOME/settings.yaml` and knowing the profile shape, and correcting a stale context window meant the same. The capability existed and the surface did not expose it.

Two things were missing, and they are not the same shape. Editing an existing route's models is a *field* on a card that already exists. Declaring a route is a *create*: the route id is being chosen, so until it is chosen there is no settings address to edit.

## Decision

The model list is a component shared by both flows; the create is its own card.

`ModelListEditor` edits a profile's `models` array — one row per model with id, display name, context window, and output cap — and owns the fetch action. An empty list means "serve this route's built-in catalog", so a row is only ever added deliberately; clearing an optional field drops it rather than storing a value the schema would reject, and a capacity that is not a positive integer is not stored at all.

Fetching asks about the endpoint **the form currently shows** — a base URL edited but unsaved, a key typed but unstored — so adding a provider is one pass instead of save-then-return. The reply opens a picker rather than being written: candidates already configured start unchecked, so adopting a selection never overwrites a capacity the user corrected. A provider that cannot be interrogated is a detour, not a dead end; the adapter's own message appears beside rows that stay editable by hand.

`CustomProviderCard` declares a route pi-ai does not ship. It is a separate card because the route id is chosen here: one `settings.mutate` sets the whole profile at `providers.<route>`, and the key travels separately through `credentials.set` under the same `<ROUTE>_API_KEY` derivation an existing provider uses. The three facts a hand-declared route cannot default — endpoint, protocol, and at least one model — gate the create button, so a failure names the field while the user is still looking at it.

The protocol choices come from the namespace's **own schema**, read through the settings descriptor the page already fetches (`providers.*.api` is a union of the adapter's `supportedProtocols()`). No new wire field, no constant in the client, and no way for the offered choices to drift from the accepted ones.

The editor reaches the two fields a route the directory reports as **declared** names for itself — its display name and that protocol. A create card asking for a field no editor can change leaves that field reachable only through `settings.yaml`, which is the posture this note set out to end. Both render in the fold beside the endpoint, the protocol from the same schema read. Clearing the name unsets it, and what the route falls back to is the layer beneath the one the field edits — a `cordis.yml` may pin a name for a route the catalog does not ship, so the placeholder reads the composition layer and names the route id only when nothing pins one. The protocol has no fallback to clear to. Because an apply can now rename the route, the saved notice names it as the refreshed directory reports it rather than as the target captured when the card opened. A catalog route gets neither: it defaults its name from its catalog entry, and each of its models carries its own protocol, so a route-level one could only override every one of them.

The **Provider ID** is the one create-card field that stays fixed, and not for want of a control. It is the `providers.<route>` dict key, so changing it is a move rather than an edit, and the editor is addressed by the `settingsPath` that move would invalidate. It is referenced from outside this namespace — `agent-default-model` stores a `provider` string, and every `request/header` in every session log already records one — so a rename would silently strip meaning from referents this page cannot see. And it is the stem of the derived credential reference: the page writes keys but can never read one back, so it cannot move `OLD_API_KEY` to `NEW_API_KEY`, leaving a rename to either orphan the stored key or point the profile at a reference under the previous name. Declaring the new route and deleting the old one does all three explicitly, and the page already offers both halves.

## Alternatives considered

**Declare a provider through `ProviderEditor` with extra fields.** One card instead of two, but the editor is addressed by `settingsPath`, and a route being named has no path yet. Recomputing the path per keystroke would remount the card and discard the draft; deferring it would mean the editor's whole write path no longer described what it was editing.

**Add a wire field for the protocol list.** Explicit. But the settings schema already crosses the wire and already contains the union, so a second copy could disagree with the first — and the one the adapter enforces is the schema.

**Let the Provider ID be edited, with the page performing the move.** The card would unset the old key and set the new profile in one `settings.mutate`, and the rest is a rename. But the credential cannot travel with it — the page holds a redacted descriptor, never a value — and the referents in other namespaces and in logged sessions have no rename path at all, so the honest version of this feature is the create-then-delete the page already has.

**Offer the protocol on every pi-ai route, with an inherit choice.** Symmetric with the base URL beside it, and repointing a catalog route at a gateway speaking another wire protocol is a real thing to want. But no consumer asks for it, one wrong pick silently repoints every model on the route, and the inherit choice would be the only way to write a declared route into a profile the adapter refuses. `settings.yaml` still expresses the repoint for a deployment that means it.

**Fetch against the stored profile instead of the live form.** No key would leave the form for an unsaved provider. But the flow that needs fetching most is the one where nothing is stored yet, and a form whose endpoint was edited would quietly interrogate the old one.

**Write adopted candidates straight into the list.** Fewer clicks, but a fetch would then overwrite capacities the user had corrected, and a listing that discloses only ids would replace real numbers with nothing.

## Consequences

A gateway, a self-hosted server, or a model newer than the installed catalog is now configurable without leaving the browser, and the endpoint itself supplies the model ids where it can. The page grew two components and one shared list editor; the editor card's pi-ai fold grew from two fields to a list, plus a name and a protocol on a declared route.

What it costs: only pi-ai routes can be hand-declared, because `llm-pi-ai` is the one namespace whose profiles describe a whole provider — a `llm-deepseek` route stays a composition fact. Interrogation reaches only OpenAI-compatible endpoints, so a gateway speaking another protocol reports that it cannot be asked and its models are typed in. And the page now holds a key in component state for the duration of a fetch, which is the same exposure `credentials.set` already has and no longer than the card lives.

## Testing

`packages/client/ui-settings-models/tests/provider-form.client.spec.tsx` drives the rendered page over a scripted wire face: adding, editing, and removing rows; a cleared optional field leaving the profile and a non-integer capacity never entering it; the interrogation carrying the edited endpoint, the unsaved key, and the profile's protocol; the picker's default selection, toggling, cancel, and adopt-keeps-tuned-rows; the empty, refused, and rejected-transport paths; the create writing one profile plus its credential; every gate on the create button; and the read-only posture. `protocolChoices` is covered against a schema that declares the union and one that does not. The stylesheet gate reads the package's own sources and fails any `<select>` that takes `.input` without `.selectInput`, because the OS arrow it would otherwise keep sits flush inside the 240px cap `select.input` imposes. The editor's own field inventory is asserted per route kind — a catalog route stops at the key and the endpoint, a declared one also carries the protocol — along with the protocol edit travelling as a single `api` path op, a rename travelling as a single `displayName` one, a cleared name unsetting rather than storing the empty string the adapter refuses, and a declared profile naming no protocol selecting nothing rather than the first choice. `apps/web/tests/models-settings.e2e.ts` reopens the declared route through the real wire, captures the card, and asserts the chosen protocol and the new name both reach `settings.yaml` and the row re-registers under the rename.
