[raiseCatError]

Problem

The Tests workflow fails on every draft PR based on release/app-store-rc (#24–#28) at Build iOS receiver app on Xcode 26.6 (macos-26 runner, iPhoneOS 26.5 SDK, Debug):

iOS/ReceiverControls.swift:1426:13: error: the compiler is unable to type-check this expression in reasonable time

(Line 1488 on #27, which only shifts the same code down.) The Mac tests in those runs pass; only the iOS build fails. Local Xcode 27.1 (Swift 6.4) compiles the same code.

Cause

edgeLayoutContent(mode:container:) is a @ViewBuilder function, so its whole body is solved as one constraint system. The rects: argument of the Strip/Overlay hit region joined three operands with +, and none of them had a known type: a ternary with an empty [], gearFrame.map { [...] } ?? [], and wheel.map { [...] } ?? paletteFrame.map { [$0] } ?? []. The solver therefore tries every + overload (Array, RangeReplaceableCollection, SIMD, CGFloat, Measurement, …) against each ?? and literal choice. Color.clear is only where the diagnostic lands, at the start of the statement.

Measured locally with Swift 6.4, with its newer solver optimisations turned off to approximate Xcode 26's solver (-solver-disable-prune-disjunctions -solver-disable-prepared-overloads -solver-disable-optimize-operator-defaults):

	before	after
solver scopes for edgeLayoutContent	175,502	14,049
trail steps	4.43 M	358 K
disjunction attempts at the two + (1431:25, 1432:25)	125,130	—
Color.clear statement	1,208 ms	below the 200 ms report threshold

Change

Three explicitly typed [CGRect] lets ahead of the ZStack (main controls, gear, palette or Wheel), concatenated in the contentShape call. These are the same expressions in the same order, so ControlRegionShape gets the same rects. The view tree, modifiers, gesture and hit-testing are unchanged. The Custom layout's hit region (which type-checks fine on CI) is untouched.

Verification

• Xcode 27.1: OpenSidecariOS generic-iOS Debug build succeeds, with no new warnings
• Mac unit tests for the receiver controls (358 tests in 11 classes, including ReceiverControlsTests, PadControlLayoutTests, SmartTouchTests and CustomLayoutRefinementTests): pass
• git diff --check is clean
• Xcode 26.6 (Swift 6.3.3, build 17F113, iPhoneOS 26.5 SDK), Tests run 40285399141: Mac tests, Mac receiver build, iOS receiver build and the reserved-region SDK gate all pass
• Dry-run merges into feat(mac): independent Mirror/Extend per connected device #24–fix(mac): preserve virtual-display arrangement after delayed wake recovery #28 are all clean. fix(ios): touch-control UX fixes, a Return key and 8× local zoom #27 is the only one that touches this file, and the combined fix(ios): touch-control UX fixes, a Return key and 8× local zoom #27 + this PR tree builds on Xcode 27.1, with the same solver cost as above (14,054 scopes)