sync: project quota, provider status, todo triage, and full diffs to the phone

Four Mac surfaces the iOS remote couldn't render now ride the wire,
forward-compatibly (decodeIfPresent defaults; unknown HostMsg tags
already decode to .unknown):

- DashboardSnapshot gains `usage` (WireSubscriptionUsage — the Mac's
  5-hour/weekly quota gauges) and `statusFeeds` (WireStatusFeed —
  active provider incidents); the host re-pushes the dashboard when a
  poll changes either.
- WireTodo gains `triage` (raw TriageLevel name); the phone renders
  the Mac's TriageBadge honoring the encouraging/classic label
  setting.
- ClientMsg.fetchDiff / HostMsg.sessionDiff deliver the full worktree
  patch on demand (capped at 512 KB with a truncated flag), gated on
  the new WireCapabilities.canFetchDiff so a new phone never sends it
  to an old host. iOS renders a file list + colored unified patch,
  falling back to the diffstat summary against older hosts.

Round-trip and legacy-decode tests cover the new fields; the full
suite passes apart from the pre-existing fake-backend fixture gaps
and the flaky nvrsion lock-domain test (same failure rate on the
base commit).

Co-Authored-By: Claude Fable 5 <[email protected]>

NucleicRemote/NucleicRemote/Views/SessionDetailView.swift

@@ -6,7 +6,9 @@ import NucleicProtocol
 struct SessionDetailView: View {
     @EnvironmentObject var store: RemoteStore
     let sessionID: SessionID
-    @State private var tab = 0
+    // Initial tab (0 = Transcript, 1 = Diff); overridable via NUCLEIC_DETAIL_TAB for
+    // offline UI previews, matching NUCLEIC_TAB / NUCLEIC_DEMO_SESSION.
+    @State private var tab = Int(ProcessInfo.processInfo.environment["NUCLEIC_DETAIL_TAB"] ?? "") ?? 0
     @State private var draft = ""
     @State private var showRename = false
     @State private var renameDraft = ""
@@ -33,7 +35,11 @@ struct SessionDetailView: View {
 
             if tab == 0 {
                 TranscriptList(events: store.openEvents)
+            } else if store.capabilities.canFetchDiff || store.openDiff != nil {
+                SessionDiffView(diff: store.openDiff, loading: store.diffLoading)
+                    .onAppear { store.fetchDiff(sessionID) }
             } else {
+                // Older host with no on-demand diff — the stat summary is all it projects.
                 DiffSummaryView(diffStat: summary?.diffStat)
             }
 
@@ -304,6 +310,112 @@ struct TranscriptList: View {
     }
 }
 
+/// The Diff tab with the real patch (the Mac Diff tab, phone form): a per-file summary list
+/// over the unified patch, colored +/− per line, fetched on demand via `fetchDiff`.
+struct SessionDiffView: View {
+    let diff: WireSessionDiff?
+    let loading: Bool
+
+    var body: some View {
+        if let diff, diff.stat.filesChanged > 0 {
+            ScrollView {
+                VStack(alignment: .leading, spacing: 14) {
+                    fileList(diff)
+                    PatchText(patch: diff.patch)
+                    if diff.truncated {
+                        Label("Patch truncated — open the Mac for the rest.",
+                              systemImage: "scissors")
+                            .font(.caption).foregroundStyle(.secondary)
+                    }
+                }
+                .padding()
+            }
+        } else if loading {
+            ProgressView("Fetching diff…")
+                .frame(maxWidth: .infinity, maxHeight: .infinity)
+        } else {
+            ContentUnavailableView("No changes yet", systemImage: "doc")
+        }
+    }
+
+    private func fileList(_ diff: WireSessionDiff) -> some View {
+        VStack(alignment: .leading, spacing: 6) {
+            Text("\(diff.stat.filesChanged) file\(diff.stat.filesChanged == 1 ? "" : "s") changed · +\(diff.stat.added) −\(diff.stat.removed)")
+                .font(.subheadline.weight(.semibold))
+            ForEach(diff.files) { file in
+                HStack(spacing: 8) {
+                    Image(systemName: statusIcon(file.status))
+                        .font(.caption)
+                        .foregroundStyle(statusColor(file.status))
+                    Text(file.path)
+                        .font(.caption.monospaced())
+                        .lineLimit(1).truncationMode(.middle)
+                    Spacer(minLength: 8)
+                    Text("+\(file.added)").font(.caption2.monospacedDigit()).foregroundStyle(Palette.success)
+                    Text("−\(file.removed)").font(.caption2.monospacedDigit()).foregroundStyle(Palette.danger)
+                }
+            }
+        }
+        .card()
+    }
+
+    private func statusIcon(_ status: String) -> String {
+        switch status {
+        case "added", "untracked": "plus.circle"
+        case "deleted": "minus.circle"
+        case "renamed": "arrow.right.circle"
+        default: "pencil.circle"
+        }
+    }
+
+    private func statusColor(_ status: String) -> Color {
+        switch status {
+        case "added", "untracked": Palette.success
+        case "deleted": Palette.danger
+        default: .secondary
+        }
+    }
+}
+
+/// The unified patch, one `Text` per line with the classic +/− coloring. Lines scroll
+/// horizontally as a block so long lines don't wrap into noise.
+private struct PatchText: View {
+    let patch: String
+
+    var body: some View {
+        ScrollView(.horizontal, showsIndicators: false) {
+            VStack(alignment: .leading, spacing: 0) {
+                ForEach(Array(patch.components(separatedBy: "\n").enumerated()), id: \.offset) { _, line in
+                    Text(line.isEmpty ? " " : line)
+                        .font(.caption.monospaced())
+                        .foregroundStyle(lineColor(line))
+                        .frame(maxWidth: .infinity, alignment: .leading)
+                        .background(lineBackground(line))
+                }
+            }
+            .textSelection(.enabled)
+            .padding(8)
+        }
+        .background(Color(.secondarySystemBackground), in: RoundedRectangle(cornerRadius: 10))
+    }
+
+    private func lineColor(_ line: String) -> Color {
+        if line.hasPrefix("+++") || line.hasPrefix("---") { return .secondary }
+        if line.hasPrefix("+") { return Palette.success }
+        if line.hasPrefix("-") { return Palette.danger }
+        if line.hasPrefix("@@") { return Palette.active }
+        if line.hasPrefix("diff ") { return .secondary }
+        return Palette.primaryText
+    }
+
+    private func lineBackground(_ line: String) -> Color {
+        if line.hasPrefix("+++") || line.hasPrefix("---") { return .clear }
+        if line.hasPrefix("+") { return Palette.success.opacity(0.10) }
+        if line.hasPrefix("-") { return Palette.danger.opacity(0.10) }
+        return .clear
+    }
+}
+
 struct DiffSummaryView: View {
     let diffStat: DiffStat?