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ios: isolate Agent input and read observation

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buzzert
2026-10-16 11:51:07 -07:00
parent 7510603b77
commit bbaa5e8859
5 changed files with 390 additions and 199 deletions
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ios/Packages/Sybil/Sources/Sybil/SybilAgentView.swift
+201 -146
View File
@@ -1,25 +1,39 @@
import SwiftUI
import Observation
struct SybilAgentView: View {
@Bindable var room: SybilAgentRoom
var room: SybilAgentRoom
var topInset: CGFloat = 0
@Environment(\.scenePhase) private var scenePhase
@State private var latestRequest = 0
var body: some View {
VStack(spacing: 0) {
AgentTranscriptView(room: room, topInset: topInset, latestRequest: latestRequest)
AgentStatusBar(room: room)
AgentComposer(room: room) { latestRequest += 1 }
}
.onAppear { room.isSelected = true }
.onDisappear { room.isSelected = false }
}
}
// Draft edits and keyboard focus belong to the composer. The transcript observes
// only room/render/scroll state; resizing is handled by its scroll geometry.
private struct AgentTranscriptView: View {
var room: SybilAgentRoom
var topInset: CGFloat
var latestRequest: Int
@Environment(\.accessibilityReduceMotion) private var reduceMotion
@FocusState private var composerFocused: Bool
@State private var atLatest = true
@State private var isScrolling = false
@State private var historyLimit = 100
@State private var historyStartID: String?
@State private var scrollPosition = ScrollPosition()
@State private var scrollTracking = AgentScrollTracking()
@State private var atBottom = false
@State private var restoreAnchor: AgentReadingAnchor?
@State private var appeared = false
private let bottomID = "agent-bottom"
private var readKey: String {
"\(room.snapshot.room.cursor):\(atLatest):\(atBottom):\(isScrolling):\(room.isObscured):\(room.isModalPresented):\(room.isAttachmentModalPresented):\(scenePhase == .active):\(room.isLoading):\(room.snapshot.revision)"
}
private var visibleReadingAnchor: AgentReadingAnchor? {
scrollTracking.rowFrames.filter { $0.value.maxY > topInset && $0.value.minY < scrollTracking.metrics.height }
.min { $0.value.minY < $1.value.minY }
@@ -35,149 +49,176 @@ struct SybilAgentView: View {
let allMessages = transcript.messages
let startIndex = transcript.startIndex
let displayed = transcript.displayed
VStack(spacing: 0) {
ScrollViewReader { proxy in
ScrollView {
VStack(alignment: .leading, spacing: 15) {
if allMessages.count > displayed.count {
Button("Load earlier messages") {
if var anchor = visibleReadingAnchor {
anchor.expectedCount = min(allMessages.count, displayed.count + 100)
restoreAnchor = anchor
}
atLatest = false
historyLimit += 100
historyStartID = allMessages[max(0, startIndex - 100)].id
ScrollViewReader { proxy in
ScrollView {
// Exact eager geometry preserves reading/prepend offsets. Lazy
// estimates required repeated corrections and failed those anchors;
// isolate observation instead of adding a geometry feedback loop.
VStack(alignment: .leading, spacing: 15) {
if allMessages.count > displayed.count {
Button("Load earlier messages") {
if var anchor = visibleReadingAnchor {
anchor.expectedCount = min(allMessages.count, displayed.count + 100)
restoreAnchor = anchor
}
.frame(maxWidth: .infinity)
.padding(.vertical, 10)
atLatest = false
historyLimit += 100
historyStartID = allMessages[max(0, startIndex - 100)].id
}
if room.isLoading { ProgressView("Loading messages…").frame(maxWidth: .infinity) }
ForEach(Array(displayed.enumerated()), id: \.element.id) { index, message in
AgentTranscriptRow(message: message, room: room,
startsDay: index == 0 || !Calendar.current.isDate(message.createdAt, inSameDayAs: displayed[index - 1].createdAt))
.equatable()
.modifier(AgentEntrance(animate: appeared && rendered.entranceIDs.contains(message.id), reduceMotion: reduceMotion))
.id(message.id)
}
if rendered.isTyping {
HStack(spacing: 9) {
AgentAvatar()
ProgressView().controlSize(.small)
Text("Sybil is thinking…").font(.sybil(.caption))
}
.foregroundStyle(SybilTheme.textMuted)
.accessibilityIdentifier("agent-typing")
}
Color.clear.frame(height: 1).id(bottomID)
.frame(maxWidth: .infinity)
.padding(.vertical, 10)
}
.scrollTargetLayout()
.padding(.horizontal, 16)
.padding(.bottom, 16)
// Match normal chat: content clears the header, while the
// viewport extends beneath the shared navigation fade.
.padding(.top, 16 + topInset)
.frame(maxWidth: SybilLayout.webContentMaxWidth)
.frame(maxWidth: .infinity)
}
.coordinateSpace(name: "agent-scroll")
.scrollPosition($scrollPosition)
.defaultScrollAnchor(.bottom, for: .initialOffset)
.defaultScrollAnchor(.bottom, for: .alignment)
.scrollDismissesKeyboard(.interactively)
.onScrollPhaseChange { _, phase in
isScrolling = phase.isScrolling
if phase == .interacting || phase == .tracking { restoreAnchor = nil }
}
.onScrollGeometryChange(for: AgentScrollMetrics.self) { geometry in
AgentScrollMetrics(offset: geometry.contentOffset.y,
height: geometry.containerSize.height,
contentHeight: geometry.contentSize.height,
bottomInset: geometry.contentInsets.bottom, topInset: geometry.contentInsets.top,
visibleBottom: geometry.visibleRect.maxY)
} action: { previous, next in
#if DEBUG
AgentRenderDiagnostics.record("scrollGeometry")
#endif
scrollTracking.metrics = next
if atBottom != next.atBottom { atBottom = next.atBottom }
if isScrolling || next.contentHeight <= next.height { atLatest = next.atBottom }
if atLatest, !isScrolling, restoreAnchor == nil,
previous.height != next.height || previous.contentHeight != next.contentHeight || previous.bottomInset != next.bottomInset {
proxy.scrollTo(bottomID, anchor: .bottom)
if room.isLoading { ProgressView("Loading messages…").frame(maxWidth: .infinity) }
ForEach(Array(displayed.enumerated()), id: \.element.id) { index, message in
AgentTranscriptRow(message: message, room: room, tracksReadingAnchor: !atLatest,
startsDay: index == 0 || !Calendar.current.isDate(message.createdAt, inSameDayAs: displayed[index - 1].createdAt))
.equatable()
.modifier(AgentEntrance(animate: appeared && rendered.entranceIDs.contains(message.id), reduceMotion: reduceMotion))
.id(message.id)
}
}
.onPreferenceChange(AgentRowFrames.self) { frames in
#if DEBUG
AgentRenderDiagnostics.record("rowPreferences")
#endif
let anchor = restoreAnchor ?? (!atLatest && !isScrolling ? visibleReadingAnchor : nil)
if let anchor, let frame = frames[anchor.id], abs(frame.minY - anchor.offset) > 1 {
// Restore the exact pixel offset after insertion or text
// reflow. Normalize the saved frames to
// the requested offset so the next layout cannot undo it.
let requested = scrollTracking.metrics.offset + frame.minY - anchor.offset
let target = min(max(requested, -scrollTracking.metrics.topInset), scrollTracking.metrics.maximumOffset)
let appliedShift = target - scrollTracking.metrics.offset
scrollTracking.rowFrames = frames.mapValues { $0.offsetBy(dx: 0, dy: -appliedShift) }
if abs(appliedShift) > 1 {
// Geometry reports the raw offset; ScrollPosition uses
// zero at the top inset, including the safe area.
scrollPosition.scrollTo(y: target + scrollTracking.metrics.topInset)
if rendered.isTyping {
HStack(spacing: 9) {
AgentAvatar()
ProgressView().controlSize(.small)
Text("Sybil is thinking…").font(.sybil(.caption))
}
restoreAnchor = nil
} else {
scrollTracking.rowFrames = frames
if let expected = restoreAnchor?.expectedCount, frames.count >= expected { restoreAnchor = nil }
.foregroundStyle(SybilTheme.textMuted)
.accessibilityIdentifier("agent-typing")
}
Color.clear.frame(height: 1).id(bottomID)
}
.overlay(alignment: .bottomTrailing) {
if !atLatest {
Button {
atLatest = true
withAnimation(reduceMotion ? nil : .easeOut(duration: 0.24)) { proxy.scrollTo(bottomID, anchor: .bottom) }
} label: {
Label(room.unreadCount > 0 ? "\(room.unreadCount) unread" : "Latest", systemImage: "arrow.down")
.font(.sybil(.caption, weight: .semibold))
.padding(12)
.background(SybilTheme.surfaceStrong, in: Capsule())
.overlay(Capsule().stroke(SybilTheme.border))
}
.padding(14)
.accessibilityIdentifier("agent-jump-latest")
}
}
.onAppear {
appeared = true
if !room.isLoading { historyStartID = displayed.first?.id }
}
.onChange(of: room.isLoading) { _, loading in
if !loading && historyStartID == nil { historyStartID = displayed.first?.id }
}
.onChange(of: allMessages.count) { _, _ in
if atLatest { proxy.scrollTo(bottomID, anchor: .bottom) }
}
.onChange(of: composerFocused) { _, _ in
if atLatest { proxy.scrollTo(bottomID, anchor: .bottom) }
.scrollTargetLayout()
.padding(.horizontal, 16)
.padding(.bottom, 16)
// Match normal chat: content clears the header, while the
// viewport extends beneath the shared navigation fade.
.padding(.top, 16 + topInset)
.frame(maxWidth: SybilLayout.webContentMaxWidth)
.frame(maxWidth: .infinity)
}
.accessibilityIdentifier("agent-transcript")
.coordinateSpace(name: "agent-scroll")
.scrollPosition($scrollPosition)
.defaultScrollAnchor(.bottom, for: .initialOffset)
.defaultScrollAnchor(.bottom, for: .alignment)
.scrollDismissesKeyboard(.interactively)
.onScrollPhaseChange { _, phase in
isScrolling = phase.isScrolling
if phase == .interacting || phase == .tracking { restoreAnchor = nil }
}
.onScrollGeometryChange(for: AgentScrollMetrics.self) { geometry in
AgentScrollMetrics(offset: geometry.contentOffset.y,
height: geometry.containerSize.height,
contentHeight: geometry.contentSize.height,
bottomInset: geometry.contentInsets.bottom, topInset: geometry.contentInsets.top,
visibleBottom: geometry.visibleRect.maxY)
} action: { previous, next in
#if DEBUG
AgentRenderDiagnostics.record("scrollGeometry")
#endif
scrollTracking.metrics = next
if scrollTracking.atBottom != next.atBottom { scrollTracking.atBottom = next.atBottom }
if isScrolling || next.contentHeight <= next.height { atLatest = next.atBottom }
if atLatest, !isScrolling, restoreAnchor == nil,
previous.height != next.height || previous.contentHeight != next.contentHeight || previous.bottomInset != next.bottomInset {
proxy.scrollTo(bottomID, anchor: .bottom)
}
}
statusBar
composer
.onPreferenceChange(AgentRowFrames.self) { frames in
#if DEBUG
AgentRenderDiagnostics.record("rowPreferences")
#endif
let anchor = restoreAnchor ?? (!atLatest && !isScrolling ? visibleReadingAnchor : nil)
if let anchor, let frame = frames[anchor.id], abs(frame.minY - anchor.offset) > 1 {
// Restore the exact pixel offset after insertion or text
// reflow. Normalize the saved frames to
// the requested offset so the next layout cannot undo it.
let requested = scrollTracking.metrics.offset + frame.minY - anchor.offset
let target = min(max(requested, -scrollTracking.metrics.topInset), scrollTracking.metrics.maximumOffset)
let appliedShift = target - scrollTracking.metrics.offset
scrollTracking.rowFrames = frames.mapValues { $0.offsetBy(dx: 0, dy: -appliedShift) }
if abs(appliedShift) > 1 {
// Geometry reports the raw offset; ScrollPosition uses
// zero at the top inset, including the safe area.
scrollPosition.scrollTo(y: target + scrollTracking.metrics.topInset)
}
restoreAnchor = nil
} else {
scrollTracking.rowFrames = frames
if let expected = restoreAnchor?.expectedCount, frames.count >= expected { restoreAnchor = nil }
}
}
.overlay(alignment: .bottomTrailing) {
if !atLatest {
Button {
restoreAnchor = nil
atLatest = true
withAnimation(reduceMotion ? nil : .easeOut(duration: 0.24)) { proxy.scrollTo(bottomID, anchor: .bottom) }
} label: {
Label(room.unreadCount > 0 ? "\(room.unreadCount) unread" : "Latest", systemImage: "arrow.down")
.font(.sybil(.caption, weight: .semibold))
.padding(12)
.background(SybilTheme.surfaceStrong, in: Capsule())
.overlay(Capsule().stroke(SybilTheme.border))
}
.padding(14)
.accessibilityIdentifier("agent-jump-latest")
}
}
.onAppear {
appeared = true
if !room.isLoading { historyStartID = displayed.first?.id }
}
.onChange(of: room.isLoading) { _, loading in
if !loading && historyStartID == nil { historyStartID = displayed.first?.id }
}
.onChange(of: allMessages.count) { _, _ in
if atLatest { proxy.scrollTo(bottomID, anchor: .bottom) }
}
.onChange(of: latestRequest) { _, _ in
restoreAnchor = nil
atLatest = true
proxy.scrollTo(bottomID, anchor: .bottom)
}
}
.onAppear { room.isSelected = true }
.onDisappear { room.isSelected = false }
.modifier(AgentReadAcknowledgement(room: room, tracking: scrollTracking,
atLatest: atLatest, isScrolling: isScrolling))
}
}
// Bottom proximity can change twice per entrance/keyboard frame while the
// scroll view follows the growing content. Only the read-settling task needs
// those transitions; they must not project and rebuild the transcript hierarchy.
private struct AgentReadAcknowledgement: ViewModifier {
var room: SybilAgentRoom
var tracking: AgentScrollTracking
var atLatest: Bool
var isScrolling: Bool
@Environment(\.scenePhase) private var scenePhase
@Environment(\.accessibilityReduceMotion) private var reduceMotion
private var readKey: String {
"\(room.snapshot.room.cursor):\(atLatest):\(tracking.atBottom):\(isScrolling):\(room.isObscured):\(room.isModalPresented):\(room.isAttachmentModalPresented):\(scenePhase == .active):\(room.isLoading):\(room.snapshot.revision)"
}
func body(content: Content) -> some View {
let cursor = room.snapshot.room.cursor
content
.task(id: readKey) {
// This cursor belongs to the rendered snapshot. New network input cancels
// the task, and cannot be acknowledged while still entering the layout.
let cursor = rendered.room.cursor
guard atLatest, scrollTracking.metrics.atBottom, !isScrolling, !room.isObscured, !room.isModalPresented, !room.isAttachmentModalPresented, scenePhase == .active, !room.isLoading else { return }
// Capture the rendered cursor before scheduling. New network input
// cancels this task and must settle in layout before acknowledgement.
guard atLatest, tracking.metrics.atBottom, !isScrolling, !room.isObscured, !room.isModalPresented, !room.isAttachmentModalPresented, scenePhase == .active, !room.isLoading else { return }
try? await Task.sleep(for: .milliseconds(reduceMotion ? 80 : 360))
guard !Task.isCancelled, atLatest, scrollTracking.metrics.atBottom, !isScrolling, !room.isObscured, !room.isModalPresented, !room.isAttachmentModalPresented, scenePhase == .active else { return }
guard !Task.isCancelled, atLatest, tracking.metrics.atBottom, !isScrolling, !room.isObscured, !room.isModalPresented, !room.isAttachmentModalPresented, scenePhase == .active else { return }
room.markRead(renderedCursor: cursor)
}
}
}
@ViewBuilder private var statusBar: some View {
private struct AgentStatusBar: View {
var room: SybilAgentRoom
@ViewBuilder var body: some View {
let activity = room.snapshot.room.activity
if let error = room.error ?? activity.error {
HStack(alignment: .top) {
@@ -199,12 +240,18 @@ struct SybilAgentView: View {
.padding(.horizontal, 16).padding(.vertical, 6)
}
}
}
private struct AgentComposer: View {
@Bindable var room: SybilAgentRoom
var onSubmit: () -> Void
@FocusState private var composerFocused: Bool
private var canSendComposer: Bool {
room.attachmentDraft.canSend
}
private var composer: some View {
var body: some View {
AgentAttachmentComposer(room: room) {
SybilPromptField(
text: $room.composer,
@@ -223,7 +270,7 @@ struct SybilAgentView: View {
private func submitComposer() {
guard canSendComposer, room.sendComposer() else { return }
atLatest = true
onSubmit()
}
}
@@ -236,16 +283,17 @@ struct AgentAvatar: View {
}
}
// Activity/read publications still update the surrounding view. Completed rows
// depend only on their message values and date heading, so progress changes
// must not rebuild the eager history (whose exact heights preserve anchors).
// Activity/read publications still update the transcript. Completed rows depend
// only on message values, heading and whether a reading anchor is needed.
private struct AgentTranscriptRow: View, Equatable {
var message: Message
var room: SybilAgentRoom
var tracksReadingAnchor: Bool
var startsDay: Bool
nonisolated static func == (lhs: Self, rhs: Self) -> Bool {
lhs.message == rhs.message && lhs.room === rhs.room && lhs.startsDay == rhs.startsDay
&& lhs.tracksReadingAnchor == rhs.tracksReadingAnchor
}
var body: some View {
@@ -261,9 +309,15 @@ private struct AgentTranscriptRow: View, Equatable {
.padding(.vertical, 6)
}
AgentMessageRow(message: message, room: room)
.background(GeometryReader { geometry in
Color.clear.preference(key: AgentRowFrames.self, value: [message.id: geometry.frame(in: .named("agent-scroll"))])
})
.background {
// Pinned-bottom layout needs only the scroll view's metrics.
// Rows report frames only while preserving a reading anchor.
if tracksReadingAnchor {
GeometryReader { geometry in
Color.clear.preference(key: AgentRowFrames.self, value: [message.id: geometry.frame(in: .named("agent-scroll"))])
}
}
}
}
}
}
@@ -330,10 +384,11 @@ private struct AgentEntrance: ViewModifier {
// Pixel geometry is imperative anchor bookkeeping, not rendered content. Keeping
// it outside observation avoids rebuilding the entire transcript on every scroll
// frame. Only the at-bottom boundary above invalidates the read acknowledgement.
private final class AgentScrollTracking {
var metrics = AgentScrollMetrics()
var rowFrames: [String: CGRect] = [:]
// frame. Only the at-bottom boundary invalidates the read acknowledgement.
@Observable private final class AgentScrollTracking {
var atBottom = false
@ObservationIgnored var metrics = AgentScrollMetrics()
@ObservationIgnored var rowFrames: [String: CGRect] = [:]
}
private struct AgentScrollMetrics: Equatable {