iOS: preserve workspace groups in Recent Activity - #9960

Packages/iOS/CmuxMobileShellUI/Sources/CmuxMobileShellUI/WorkspaceListView.swift (1)

344-348: 🚀 Performance & Scalability | 🟠 Major | ⚡ Quick win

Replace the per-header workspace scan with one lookup.

Recent Activity now renders grouped sections. groupedRows then calls workspaces.first(where:) at line 905 for every group header. With 200 groups and 1,000 workspaces, this performs up to 200,000 comparisons on each list render.

Build one workspace-ID-to-capabilities dictionary before ForEach. Use that dictionary for the anchor lookup.

Proposed fix

 private func groupedRows(
     items: [MobileWorkspaceListItem]
 ) -> some View {
     let enablesReorder = enablesWorkspaceReorder
     let groupLookup = groupsByID
+    let capabilitiesByWorkspaceID = Dictionary(
+        workspaces.map { ($0.id, $0.actionCapabilities) },
+        uniquingKeysWith: { first, _ in first }
+    )
     ForEach(items, id: \.id) { item in
         switch item {
         case .groupHeader(let group, let hasUnread):
-            let anchorCapabilities = workspaces.first(where: { $0.id == group.anchorWorkspaceID })?.actionCapabilities ?? .none
+            let anchorCapabilities = capabilitiesByWorkspaceID[group.anchorWorkspaceID] ?? .none

As per coding guidelines, production code must avoid repeated full scans for workloads around 1,000 records. As per path instructions, .github/review-bot-rules/algorithmic-complexity.md applies this rule to scalable user data.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In
`@Packages/iOS/CmuxMobileShellUI/Sources/CmuxMobileShellUI/WorkspaceListView.swift`
around lines 344 - 348, Update the grouped-row rendering path around
rendersGroupedSections and groupedRows to build a single
workspace-ID-to-capabilities dictionary before ForEach, then use that lookup for
each group header’s anchor workspace instead of calling
workspaces.first(where:). Preserve the existing grouping and anchor behavior
while eliminating repeated full workspace scans.

Sources: Coding guidelines, Path instructions

Packages/iOS/CmuxMobileShellUI/Sources/CmuxMobileShellUI/WorkspaceListView.swift (1)

457-481: 🚀 Performance & Scalability | 🔵 Trivial | ⚡ Quick win

Avoid filtering workspaces twice per render during an active drag.

currentDisplayedGroupedListItems computes displayedGroupedWorkspaces, which reads the computed property groupedWorkspaces (an O(n) filter over workspaces) once. When optimisticGroupedState.optimisticOrder is non-nil, currentAuthoritativeGroupedListItems reads groupedWorkspaces again directly. This filter runs twice per body evaluation while a drag is active, and drag gestures trigger many render passes.

Hoist groupedWorkspaces into a single local let at the top of body and pass that value to both the displayed and authoritative branches instead of letting each branch re-read the computed property.

As per path instructions, .github/review-bot-rules/algorithmic-complexity.md requires avoiding "repeated sort/filter/map work in hot paths" for production code handling around 1,000 workspace records.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In
`@Packages/iOS/CmuxMobileShellUI/Sources/CmuxMobileShellUI/WorkspaceListView.swift`
around lines 457 - 481, Hoist the computed groupedWorkspaces value into a single
local let at the top of body, then reuse that local when constructing both
displayedGroupedWorkspaces and currentAuthoritativeGroupedListItems. Update the
displayed projection path and authoritativeGroupedProjectionCache.items call so
an active drag does not re-read the groupedWorkspaces computed property during
the same body evaluation.

Source: Path instructions