Merge remote-tracking branch 'origin/master' into worktree/default-model-persistence

Carries two edits beyond conflict resolution, both forced by what master
brought in:

- `CustomProviderCard`: master added front-end key validation and a
  component-level `keyValue` (already trimmed) while still writing
  `apiKeyEnv` unconditionally. Kept this branch's blank-key rule and its
  committed-profile retry gate, and adopted master's single `keyValue` so
  the component has one spelling of the key rather than two.
- `docs/user/guide/providers`: master merged #1810, whose default-model
  section still taught overriding the `api-gateway` row in
  `$DSH_HOME/config.yaml` — the behavior this branch replaced. Rewritten
  for the settings section the picker now writes, plus the review fix from
  #1810 replacing the colloquial 挂着 in the opener.

packages/client/ui-models/README.md

@@ -8,7 +8,7 @@ Rows are the *configured* providers (their profile resolves in the owning namesp
 
 The DeepSeek step projects `deepseek-official` readiness from that same joined snapshot after earlier onboarding pages complete. It recognizes the official adapter through its `llm-deepseek` configurable-provider declaration, so an undeclared live route with the same provider id is not treated as repairable configuration. A configured literal `apiKey` secret sidecar or configured credential reference completes the step without rendering, including a read-only launch-environment credential. Only a mounted, active adapter with a missing writable reference shows the page that opens Settings on Models, whose existing setup card exclusively owns key input and `credentials.set`; the step never holds a secret. An absent adapter, inactive route, failed join, read-only deployment, or unusable settings or credential capability completes the step without rendering so onboarding cannot block the product; Models remains the diagnostic surface.
 
-Every edit lands as `settings.mutate` path ops against the stored section — a set per changed field, an unset per cleared one, and a single unset for a deleted provider row. The page only ever holds the REDACTED descriptor, so it names the fields it can see rather than rebuilding a section: a stored literal secret it never received is mentioned by no op and survives. DeepSeek's `models` is one replace-by-value array: the editor shows inherited effective rows until the first model edit materializes the complete array in the user layer, while reset unsets that override. A row carries the model id and display name; its context window and output cap sit behind the row's own disclosure, the same shape the pi-ai provider form uses. Either capacity is typed as a count with an optional decimal `K` or `M` suffix (`256K`, `1M`; `1M` is 1000K) and stored as the plain count, spelled back in the shortest form that round-trips. Empty ids, duplicate ids, empty explicit names, and unreadable, non-positive, or fractional capacities fail before any write. Each settings write carries the card's current `revision`, so a concurrent write from another tab or an external `settings.yaml` edit is refused as `settings-conflict`; after settings commit, the card adopts the returned redacted user subtree and revision before storing the credential, which makes a failed credential stage retry only that stage. Deletion removes a configured, writable credential only when the profile names the page's derived `<ROUTE>_API_KEY` target, then unsets the profile; both operations are idempotent, and a partial failure remains in the identified confirmation dialog for retry. Environment credentials, custom references, and credentials whose target cannot be identified remain untouched. The page refetches on the pushed invalidations (`settings/changed`, `credentials/changed`, `models/changed`, and `connection/reset`) once it has loaded, so an external `settings.yaml` edit, a second tab, or a settings-born route converges without polling.
+Every edit lands as `settings.mutate` path ops against the stored section — a set per changed field, an unset per cleared one, and a single unset for a deleted provider row. The page only ever holds the REDACTED descriptor, so it names the fields it can see rather than rebuilding a section: a stored literal secret it never received is mentioned by no op and survives. DeepSeek's `models` is one replace-by-value array: the editor shows inherited effective rows until the first model edit materializes the complete array in the user layer, while reset unsets that override. A row carries the model id and display name; its context window and output cap sit behind the row's own disclosure, the same shape the pi-ai provider form uses. Either capacity is typed as a count with an optional decimal `K` or `M` suffix (`256K`, `1M`; `1M` is 1000K) and stored as the plain count, spelled back in the shortest form that round-trips. Empty ids, duplicate ids, empty explicit names, and unreadable, non-positive, or fractional capacities fail before any write. A typed API key is judged on its own field the same way: after trimming, it must be non-empty and every character must be printable ASCII (`[\x21-\x7E]`), which is exactly what an HTTP header value can carry — the twin of `normalizeApiKey` in `@deepseek-ai/dsh-llm`, mirrored here because the source-plane split forbids importing it. A value shaped like a pasted `NAME=value` environment line or wrapped in matching quotes is refused as the same format failure; that paste-shape heuristic runs only in the browser, since a false positive in a resolver would leave the environment refusing the key as well. A field holding only whitespace fails rather than being silently dropped, while an empty field is not a failure at all: it means keep the stored key on an editor card, and authenticate some other way on a create card. A refused key blocks both the write and the endpoint interrogation, so the page never spends a round trip to be told what the field already says. Each settings write carries the card's current `revision`, so a concurrent write from another tab or an external `settings.yaml` edit is refused as `settings-conflict`; after settings commit, the card adopts the returned redacted user subtree and revision before storing the credential, which makes a failed credential stage retry only that stage. Deletion removes a configured, writable credential only when the profile names the page's derived `<ROUTE>_API_KEY` target, then unsets the profile; both operations are idempotent, and a partial failure remains in the identified confirmation dialog for retry. Environment credentials, custom references, and credentials whose target cannot be identified remain untouched. The page refetches on the pushed invalidations (`settings/changed`, `credentials/changed`, `models/changed`, and `connection/reset`) once it has loaded, so an external `settings.yaml` edit, a second tab, or a settings-born route converges without polling.
 
 ## Model list and endpoint interrogation