Second parity tier: gestures and lifecycle. Adds closure-carrying modifiers, which register a callback against the resolve context and embed its id in the emitted node — wired to Compose clickable/DisposableEffect/LaunchedEffect.

New modifiers

• .onTapGesture — folds to Modifier.clickable
• .onAppear / .onDisappear — a DisposableEffect keyed within the node's identity scope, so appear fires once on entry and disappear on exit, surviving recomposition
• .task — launched once on appear as a Swift Task (v1 does not cancel on disappear)
• .onChange(of:) — fires when a value token changes between evaluations (skipping the initial composition)
• .disabled(_:) — dims content; Button also drops interactivity via its enabled parameter

Core change

Modifiers previously emitted a context-free node. Added _ContextualModifierProvider (preferred over the plain _modifierNode property when present) and _CallbackModifier, so a modifier can register a callback at resolve time. Additive — existing modifiers and conformers are untouched.

Verification

• swift test — 4 new emission tests (incl. invoking a registered tap callback), 39 total passing
• Emulator (new Interaction screen): tap counter increments, onAppear fires exactly once across recompositions, onChange counts slider changes during a drag, disabled button is dimmed and non-interactive then flips to enabled

Deferred

.task cancellation on disappear; gesture variants beyond tap (drag/long-press). Environment-scoped .disabled propagation (applies where set / directly on a Button for now).