fold: a scoped simulator set fails at the devicectl display inventory before HID dispatch

[thymikee]

Purpose and decision

fold on an iPhone Duo in --ios-simulator-device-set <set> fails before HID dispatch: CoreDevice's display inventory cannot resolve a simulator outside the default set. Hinge readback has the same dependency. Refuse scoped-set fold at runtime admission, before any display probe or HID effect. Full support requires a verified set-aware source for both the display table and hinge angle; none is available in the selected toolchain.

simctl accepts --set <path> and the HID send already uses it. devicectl device info displays and devicectl device motion hinge-angle accept --device but expose no set selector in Xcode 26.2 help. #2818's live scoped-set run found The specified device was not found. ADR 0025 requires hinge readback after motion, so successful HID alone cannot count as support. #2878 addresses simctl scope enforcement and does not solve CoreDevice scope.

Implementation contract

1. In packages/platform-apple/src/foldable/runtime.ts, make appleFoldFact(DeviceInfo) unavailable when device.simulatorSetPath is present. This is the owning fact for capability reporting and admission. Use a truthful typed reason, unsupported-device-scope; add it to the RuntimeOperationUnavailability union and its parser in packages/contracts/src/platform-runtime.ts. The resulting command failure is UNSUPPORTED_OPERATION with details.reason: 'unsupported-device-scope' and a hint naming the scoped simulator set. Do not add a second guard in pose.ts or match CoreDevice error text.
2. Preserve the existing kind/OS refusals and default-set behavior. Scope refusal must occur before any devicectl, simctl spawn, or helper build. Keep the capability result and command response consistent by deriving both from the fact.
3. Update agent-device help foldable and the fold command description to state the scoped-set limitation. Leave screenshot's separate unresolved-inventory behavior and ADR 0025 capture policy alone.

Proof and completion

• Plant a failing admission test on a scoped DeviceInfo: both the fact/capability and routed fold response must be unavailable with the typed reason, and tool spies must record zero devicectl/simctl calls. Remove the planted failure only after the production change.
• Existing default-set fold and runtime fact tests pass without argv changes. Run pnpm check:affected --run; report focused tests and help tests.
• On a throwaway foldable simulator in a temporary set, record agent-device fold half-open --ios-simulator-device-set <set> --udid <verified-udid> --json returning the typed refusal before motion. Verify the hinge/panel was not changed by this request. Do not use a simulator belonging to another task.

Future support criterion

Revisit this refusal only when a set-aware source can supply both display inventory and verified hinge readback on a scoped Duo. Preserve the same admission fact and ADR 0025 post-dispatch proof.