Fifth step of the Compose-backed architecture (#18–#21). With the pipeline proven end-to-end in #21, this grows the vocabulary: form controls, @Environment/@Observable, effect modifiers, and the first seven gallery screens — restored and rendering through Compose.

Core (host-tested)

• Primitives: Text(verbatim:), ScrollView, Color (as a fill view), Image, ProgressView, Slider, TextField, Picker (with .tag), plus LazyVStack/LazyHStack aliases.
• @Environment: object injection down a subtree via .environment(_:), read by @Environment(Model.self). Values flow down evaluation and never cross the bridge.
• @Observable: evaluate() wraps the body walk in withObservationTracking; a later mutation of any observed property schedules re-evaluation exactly like a @State write, re-arming each pass. Both use the same reflection seam as @State.
• Modifiers: cornerRadius, offset, rotationEffect, scaleEffect, opacity.

swift test: 18 tests, all passing — adds slider/text-field binding round-trips, picker tag extraction + selection mapping, environment injection reaching a nested @Environment, and an @Observable mutation firing the change hook.

Interpreter

New node types: ScrollView (scroll state), Color, ProgressView (linear/circular), Slider, TextField, Picker (dropdown). TextField uses uncontrolled-with-reconciliation — Compose owns the TextFieldValue, lastSent tracks the pushed value so an echo leaves the cursor alone and an external change adopts Swift's value with the cursor at the end. Modifier folds added for clip/offset/rotation/scale/opacity.

Gallery

Text, Buttons, Stacks, State, Controls, Modifiers, and Observation screens restored verbatim and driven through the Compose renderer, selected by a Picker (full NavigationStack/List navigation returns in the next step). The host content now insets from the system bars (safeDrawingPadding), fixing the R4 status-bar overlap.

Verification

On the emulator:

• Controls: toggle flips and drives its bound label ("Toggle is off" → "on") — the full Compose-event → JNI → Swift @State → re-evaluate → recompose round trip. Indeterminate spinner, determinate bar, slider, text field all render.
• Modifiers: all seven render correctly — padding, frame 200×60, background, clip+corner-radius, offset, rotation, scale. This is the exact modifier suite that took the entire old Phase 1 to get working against classic views; here it's plain data.
• Picker navigation between all seven screens works.

Note

AndroidKit must not be imported by app code (its AndroidView.View collides with the core's View); the umbrella re-exports the core, and AndroidSwiftUILog covers logging. The gallery screens compile unchanged against real SwiftUI on Apple platforms via the #if canImport gate.