feat(ui-models)!: single-key hand-written provider editors with derived credential references

The Models page drops the generic schema renderer and the visible
environment-variable field: each editor is a curated per-family card whose
primary input is one write-only API key stored under a derived
<ROUTE>_API_KEY reference (recorded as apiKeyEnv in the pi-ai profile), an
unkeyed whole-section provider opens as its setup card, and the collapsed
customized-settings fold carries baseURL/reasoningEffort (deepseek) or
reasoning (pi-ai). dsh-client-schema-form reduces to the schema/draft model
layer (no React).

packages/client/schema-form/README.md

@@ -2,21 +2,15 @@
 
 English | [中文](README.zh.md)
 
-Schema-driven React form renderer for settings sections. The wire's `settings.describe` carries each namespace's serialized schemastery schema (`schema.toJSON()` ref envelope); `SchemaForm` rehydrates it with `new Schema(json)` and renders every declared field as an editable control — the same schema object that validates a section on the host validates and drives the form in the browser, so there is no second form definition to drift.
+Schema/draft model layer for settings editors. The wire's `settings.describe` carries each namespace's serialized schemastery schema (`schema.toJSON()` ref envelope); `rehydrateSchema` turns it back into a live validator with `new Schema(json)` — the same schema object that validates a section on the host validates drafts in the browser, so client-side validation never drifts from the seam's. Editors render their own controls (the Models page hand-writes its card around the fields it probes here); this package owns no React and no rendering.
 
 ## Contract
 
-`SchemaForm` is a controlled component over a **draft user section**: `draft` is the object being edited (never mutated; every edit calls `onChange` with a new root), and `fallback` is the resolved value (schema defaults → composition base → user layer) used for inherited display. A field's presence in the draft marks it **overridden** and shows a per-field Reset that deletes the key, falling back to the inherited layer — presence semantics, not value comparison, exactly mirroring the settings seam's layering.
-
-Controls by schema node: `object` → labeled field groups (JSDoc `description` rendered, `required` starred), `string`/`number`/`boolean` → inputs with the inherited value as placeholder, `union` of literals → select whose empty option means "inherit", `array` → positional rows with add/remove (arrays replace wholesale on write), `dict` → keyed rows where a union-typed `sKey` becomes the add-select's vocabulary. `role('secret')` renders a **write-only** password input: the stored value never arrives (the wire strips it), and the `secrets` slot list (`{path, set}`) supplies the placeholder state. A node the renderer cannot faithfully edit (non-literal unions, transforms) renders a read-only JSON view with a notice instead of disappearing — a schema field is never silently dropped.
-
-`renderField(context)` is the role-aware override hook: return a node to replace the default control for one leaf. The Models settings page uses it to mount the credential-reference control (`role('credential-ref')`) that talks to `credentials.*` — this package stays wire-free and side-effect-free.
-
-`validateDraft(schema, draft)` runs the rehydrated validator and returns its failure message, letting pages validate before writing; the path helpers (`getPath`/`hasPath`/`setPath`/`deletePath`) expose the same immutable draft editing the controls use.
+The unit of editing is a **draft user section**: a plain object edited immutably (`setPath` materializes intermediates, `deletePath` is the per-field reset — dropping the key falls the resolved value back to the composition base and schema defaults). A field's presence in the draft marks it **overridden** (`hasPath`) — presence semantics, not value comparison, exactly mirroring the settings seam's layering. `nodeAtPath` resolves the schema node addressed by a configurable-provider directory `settingsPath` (object properties by name, dict entries through `inner`), so an editor can probe which fields a provider's profile carries (and their `meta.role`) before deciding what to render; an unresolvable path returns `undefined` so the caller degrades loudly instead of rendering a wrong subtree. `validateDraft(schema, draft)` runs the rehydrated validator and returns its failure message, letting pages reject an invalid draft before writing.
 
 ## Model Experience
 
-None, as this package renders browser configuration forms; nothing here reaches a model request.
+None, as this package backs browser configuration editors; nothing here reaches a model request.
 
 #### KV Cache effect
 
@@ -24,7 +18,5 @@ None; this package neither assembles nor sends a provider request.
 
 ## Known Limitations and Deferred Work
 
-- **Validation is form-level, not per-field** — `validateDraft` reports schemastery's first failure message (which names the `$.path`); inline per-field error placement is deferred until a second consumer needs it.
-- **Strings are built-in English** — the `labels` prop overrides every user-visible string, but there is no locale-dictionary wiring inside this package; the embedding page owns localization.
-- **Non-literal unions and transforms render read-only** — faithful editing of those shapes needs per-shape controls; today they fall back to the JSON view with a notice.
-- **Array editing replaces wholesale** — element-level merge does not exist at the settings seam either; the form mirrors that contract rather than hiding it.
+- **Validation is draft-level, not per-field** — `validateDraft` reports schemastery's first failure message (which names the `$.path`); per-field error mapping is deferred until a consumer needs it.
+- **No generic renderer** — a schema-driven form component was built and then replaced by the hand-written Models editor ([Agent Note](../../../.agents/notes/implemented/architecture/2026-07-30-web-config-plane.md)); if a future page needs to edit arbitrary sections, it starts from these helpers, not from a resurrected generic renderer, unless the note's trade-off changes.