fix(web): keep the plan card to decisions it can actually answer

Review follow-ups on the presentation intent.

The card claimed any single-question request declaring the intent, then sent one
of two labels — so a producer offering a third option, or a multi-select batch,
lost answers the generic flow would have shown. That contradicts the intent's
own contract, so `planReviewOf` now claims only a binary single choice and
leaves everything else to the flow that can express it.

`ask()` also rejects a plan-review intent on a question with no `detail`: the
intent declares detail IS the plan, and without one a honouring UI asks the
user to approve something invisible. The client keeps its own fallback — it sits
downstream of a wire boundary — but the misconfiguration now fails at the asker.

`planReviewOf` stops being a value export of the client contract face (client
export discipline: pure helpers stay internal; the tests already import it
relatively), and the ui-question README fallback list, both languages, now
states every condition the code enforces.

.agents/notes/implemented/feature/2026-07-30-plan-review-presentation-intent.md

@@ -16,11 +16,11 @@ A question may declare a **presentation intent**, and the Web composer renders a
 
 An intent shapes presentation only. The answer protocol is untouched: a UI honouring the intent answers with the same option labels a generic UI would send, so `exit_plan_mode` reads one answer shape regardless of which surface collected it, and a UI that does not know a tag renders the generic flow with nothing lost but the layout.
 
-`approve` names the affirmative option instead of relying on option order, so no UI infers a verdict from a position. Because the types cannot tie that label to the question's own option list, `UserInteractionService.ask()` rejects an intent whose `approve` names none of its options (`BAD_INTENT`) — at the asker, before any UI can answer a choice that was never offered. On the wire the intent is a discriminated union, so an unrecognised tag is a rejected frame rather than a silently generic render.
+`approve` names the affirmative option instead of relying on option order, so no UI infers a verdict from a position. Two assertions an intent makes are beyond the types, and `UserInteractionService.ask()` rejects both as `BAD_INTENT` at the asker: an `approve` naming none of that question's own options — before any UI can answer a choice never offered — and an intent on a question with no `detail`, the thing it declares itself a review of, which would ask the user to approve something invisible. On the wire the intent is a discriminated union, so an unrecognised tag is a rejected frame rather than a silently generic render.
 
 `ui-question` renders the intent as `PlanReviewPanel`, in the waiting-approval card language: the amber strip carries `Plan review`, the plan is the scrolling markdown body, and the decision row holds three actions — `Chat about it`, `Refuse`, `Approve`. The question text becomes the card's accessible name rather than a headline, because the buttons already say what the decision is. Approve and Refuse answer with the asker's own option labels and keep the asker's descriptions as tooltips; `Chat about it` cancels the request, which returns the composer so the user can simply say what they want. All copy is bilingual under the existing `question` namespace.
 
-Routing lives inside the single composer entry (`QuestionComposer` chooses the shape) rather than in a second chain registration, and `planReviewOf` claims a request only when the batch is one question that declares the intent, carries the plan as its `detail`, and offers the named approve label. Anything else stays a generic question — the client is downstream of a wire boundary, so a request it cannot render as a card must still be answerable.
+Routing lives inside the single composer entry (`QuestionComposer` chooses the shape) rather than in a second chain registration, and `planReviewOf` claims a request only when the card can send every answer that request allows: one question declaring the intent, the plan as its `detail`, the named approve label offered, and a binary single choice — at most one option besides approve, and not multi-select. A third option or a multi-select batch has answers two buttons cannot express, so the generic flow keeps it, and keeps anything else the card cannot render. "Presentation only" is therefore literal: an intent never costs the user a reachable answer, and the client — downstream of a wire boundary — leaves every request answerable.
 
 Dismissal became its own model-facing outcome. `ASK_CANCELLED` previously reached the model as "the user cancelled ask_user_question", naming a tool it never called; `exit_plan_mode` now reports that the user dismissed the review to speak instead and to stay in plan mode and wait. Every other ask failure — an abort from turn cancel or provider teardown, where no user is coming — keeps its own message.
 
@@ -50,6 +50,6 @@ A deployment whose client half predates this change still shows the quiz layout
 
 ## Testing
 
-`ui-question` tests pin the narrowing (single-question batch, intent present, plan as detail, named approve label offered, decline absent when only approve is offered) and the panel (strip, markdown plan, accessible name, absence of pager/radio/skip/custom, approve and decline answering with the asker's labels, dismissal cancelling, one-shot latch with re-arm and message on a rejected receipt, tooltips present and absent, both locales). `user-interaction` tests pin `BAD_INTENT` and intent pass-through; `plan-mode` tests pin the declared intent against its own option list and both failure messages; the apiproxy schema test pins wire acceptance and an unknown tag's rejection.
+`ui-question` tests pin the narrowing (single-question batch, intent present, plan as detail, named approve label offered, binary single choice, decline absent when only approve is offered) and the panel (strip, markdown plan, accessible name, absence of pager/radio/skip/custom, approve and decline answering with the asker's labels, dismissal cancelling, one-shot latch with re-arm and message on a rejected receipt, tooltips present and absent, both locales). `user-interaction` tests pin both `BAD_INTENT` rejections and intent pass-through; `plan-mode` tests pin the declared intent against its own option list and both failure messages; the apiproxy schema test pins wire acceptance and an unknown tag's rejection.
 
 The `plan-review` Web e2e lane records `/plan` entering plan mode for real, the model calling `exit_plan_mode`, the decision card taking the composer (asserting the generic flow did **not** claim the request), and the card's own Approve completing the turn — two keyless goldens, the waiting card and the approved transcript.