Bugfix: F8 dies after volume switch (Group A null-vs-undefined sweep)

After commit dc5f0b4 dropped `skip_serializing_if = "Option::is_none"` from `FileEntry` (and friends), absent fields started serializing as explicit JSON `null` instead of being omitted. Code that did `if (entry.size !== undefined)` then proceeded with `null` and crashed downstream — `formatDateTimeParts(null)`, `formatBytesHtml(null)`, etc. The crash inside a Svelte 5 `$effect` corrupted the reactive graph for sibling effects on the same component, which is why a state write to `showDeleteDialog = true` after a volume switch was silently dropped and the Delete dialog never mounted.

Bisected to dc5f0b4 + agent-driven sweep of every `=== undefined` / `!== undefined` site that touches IPC-derived optional fields. Eleven offenders across six files:

- `views/measure-column-widths.ts` — `entry.modifiedAt !== undefined` guarding `formatDateTimeParts(...)`. Top suspect: this `$effect` runs on every listing refresh, so the volume-switch path was the killer.
- `views/full-list-utils.ts` — `hasSizeMismatch` and `buildFileSizeTooltip` accepted `number | undefined`; widened to also accept `null`, switched all guards.
- `selection/selection-info-utils.ts` — `formatDate`, `buildDateTooltip`, `isPermissionDenied`.
- `rename/RenameConflictDialog.svelte` + `rename/rename-operations.ts` — `renamedIsNewer`/`existingFile` derived comparisons.
- `file-operations/delete/DeleteDialog.svelte` + `delete/delete-dialog-utils.ts` — `formatItemSize` and the `DeleteSourceItem` type.
- `file-explorer/pane/dialog-state.svelte.ts` — type-guard filter on per-item sizes for trash progress.

Each non-trivial fix carries a "Group A wire-format" inline comment so future devs know why we use `!= null` instead of `!== undefined` here.

Tests: svelte-check / eslint / 1739 unit tests all green.

Author: vdavid

apps/desktop/src/lib/file-explorer/pane/dialog-state.svelte.ts

@@ -308,10 +308,11 @@ export function createDialogState(deps: DialogStateDeps) {
 
       const opType: TransferOperationType = isPermanent ? 'delete' : 'trash'
 
-      // Collect per-item sizes for trash progress if available
+      // Collect per-item sizes for trash progress if available.
+      // Group A wire-format: IPC sends `null` for absent sizes, so reject both null and undefined.
       const sizes = deleteDialogProps.sourceItems
         .map((item) => (item.isDirectory ? item.recursiveSize : item.size))
-        .filter((s): s is number => s !== undefined)
+        .filter((s): s is number => s != null)
       const itemSizes = sizes.length === deleteDialogProps.sourceItems.length ? sizes : undefined
 
       transferProgressProps = {

apps/desktop/src/lib/file-explorer/rename/RenameConflictDialog.svelte

@@ -14,9 +14,10 @@
 
     const { renamedFile, existingFile, onResolve }: Props = $props()
 
+    // Group A wire-format: IPC may send `null` for modifiedAt; accept both null and undefined.
     const renamedIsNewer = $derived(
-        renamedFile.modifiedAt !== undefined &&
-            existingFile.modifiedAt !== undefined &&
+        renamedFile.modifiedAt != null &&
+            existingFile.modifiedAt != null &&
             renamedFile.modifiedAt > existingFile.modifiedAt,
     )
     const renamedIsLarger = $derived(renamedFile.size > existingFile.size)
@@ -76,7 +77,7 @@
                         class="meta-value"
                         class:newer={!renamedIsNewer &&
                             renamedFile.modifiedAt !== existingFile.modifiedAt &&
-                            existingFile.modifiedAt !== undefined}>{formatDateTime(existingFile.modifiedAt)}</span
+                            existingFile.modifiedAt != null}>{formatDateTime(existingFile.modifiedAt)}</span
                     >
                 </div>
             </div>

apps/desktop/src/lib/file-explorer/rename/rename-operations.ts

@@ -9,8 +9,8 @@ import { extensionsDifferMeaningfully, getExtension } from '$lib/utils/filename-
 export interface ConflictFileInfo {
   name: string
   size: number
-  /** Unix timestamp in seconds, or undefined if unavailable */
-  modifiedAt: number | undefined
+  /** Unix timestamp in seconds, or null/undefined if unavailable. Group A wire-format: IPC sends `null`. */
+  modifiedAt: number | null | undefined
 }
 
 export type RenameConflictResolution = 'overwrite-trash' | 'overwrite-delete' | 'cancel' | 'continue'

apps/desktop/src/lib/file-explorer/selection/selection-info-utils.ts

@@ -74,8 +74,8 @@ export function formatSizeForDisplay(
 }
 
 /** Formats timestamp as YYYY-MM-DD hh:mm:ss */
-export function formatDate(timestamp: number | undefined): string {
-  if (timestamp === undefined) return ''
+export function formatDate(timestamp: number | null | undefined): string {
+  if (timestamp == null) return ''
   const date = new Date(timestamp * 1000)
   const pad = (n: number) => String(n).padStart(2, '0')
   const year = date.getFullYear()
@@ -90,10 +90,11 @@ export function formatDate(timestamp: number | undefined): string {
 /** Builds date tooltip content */
 export function buildDateTooltip(e: FileEntry): string {
   const lines: string[] = []
-  if (e.createdAt !== undefined) lines.push(`Created: ${formatDate(e.createdAt)}`)
-  if (e.openedAt !== undefined) lines.push(`Last opened: ${formatDate(e.openedAt)}`)
-  if (e.addedAt !== undefined) lines.push(`Last moved ("added"): ${formatDate(e.addedAt)}`)
-  if (e.modifiedAt !== undefined) lines.push(`Last modified: ${formatDate(e.modifiedAt)}`)
+  // `!= null` because IPC payloads serialize `Option::None` as JSON `null`.
+  if (e.createdAt != null) lines.push(`Created: ${formatDate(e.createdAt)}`)
+  if (e.openedAt != null) lines.push(`Last opened: ${formatDate(e.openedAt)}`)
+  if (e.addedAt != null) lines.push(`Last moved ("added"): ${formatDate(e.addedAt)}`)
+  if (e.modifiedAt != null) lines.push(`Last modified: ${formatDate(e.modifiedAt)}`)
   return lines.join('\n')
 }
 
@@ -137,7 +138,7 @@ export function isBrokenSymlink(entry: FileEntry | null): boolean {
 
 /** Checks if entry has permission denied */
 export function isPermissionDenied(entry: FileEntry | null): boolean {
-  return entry !== null && !entry.isSymlink && entry.permissions === 0 && entry.size === undefined
+  return entry !== null && !entry.isSymlink && entry.permissions === 0 && entry.size == null
 }
 
 // ============================================================================

apps/desktop/src/lib/file-explorer/views/full-list-utils.ts

@@ -233,8 +233,10 @@ export function getDisplaySize(
  * Whether content and on-disk sizes differ enough to warrant a warning icon.
  * Both conditions must be true: ≥50% relative difference AND ≥200 MB absolute difference.
  */
-export function hasSizeMismatch(logical: number | undefined, physical: number | undefined): boolean {
-  if (logical === undefined || physical === undefined) return false
+// Group A wire-format: callers pass IPC-derived `number | null` values directly.
+// Use `== null` so both `null` and `undefined` count as "no value".
+export function hasSizeMismatch(logical: number | null | undefined, physical: number | null | undefined): boolean {
+  if (logical == null || physical == null) return false
   if (logical === 0 || physical === 0) return false
   const diff = Math.abs(logical - physical)
   const smaller = Math.min(logical, physical)
@@ -258,18 +260,19 @@ function sizeLineHtml(label: string, bytes: number, formatSize: (b: number) => s
  * Always shows both lines when both sizes are available. Falls back to a single line otherwise.
  */
 export function buildFileSizeTooltip(
-  logical: number | undefined,
-  physical: number | undefined,
+  logical: number | null | undefined,
+  physical: number | null | undefined,
   formatSize: (bytes: number) => string,
 ): string | { html: string } {
-  if (logical === undefined && physical === undefined) return ''
-  if (logical !== undefined && physical !== undefined) {
+  // Group A wire-format: IPC sends `null`, not `undefined`. Use `!= null` to handle both.
+  if (logical == null && physical == null) return ''
+  if (logical != null && physical != null) {
     return {
       html: `${sizeLineHtml('Content', logical, formatSize)}<br>${sizeLineHtml('On disk', physical, formatSize)}`,
     }
   }
   const size = logical ?? physical
-  if (size === undefined) return ''
+  if (size == null) return ''
   return { html: `${formatSize(size)} (${formatBytesHtml(size)} bytes)` }
 }
 

apps/desktop/src/lib/file-explorer/views/measure-column-widths.ts

@@ -286,7 +286,11 @@ export function computeFullListColumnWidths(args: {
     if (rowSize > sizeMax) sizeMax = rowSize
     if (iconSuffix > sizeIconSuffixMax) sizeIconSuffixMax = iconSuffix
 
-    if (entry.modifiedAt !== undefined) {
+    // `!= null` (not `!== undefined`): IPC payloads serialize `Option::None` as
+    // explicit `null`, and `formatDateTimeParts(null)` throws inside this `$effect`,
+    // which corrupts Svelte's reactive graph for sibling effects on the same
+    // component (this was the F8-after-volume-switch killer).
+    if (entry.modifiedAt != null) {
       date = foldDate(date, formatDateTimeParts(entry.modifiedAt), measure)
     }
   }

apps/desktop/src/lib/file-operations/delete/DeleteDialog.svelte

@@ -179,17 +179,18 @@
      *  Always uses logical (content) sizes — not worth plumbing the display mode setting
      *  through the delete dialog infrastructure for a transient confirmation dialog. */
     function formatItemSize(item: DeleteSourceItem): string {
+        // Group A wire-format: IPC sends `null` for absent fields, not `undefined`.
         if (item.isDirectory) {
             const size = item.recursiveSize
             const fileCount = item.recursiveFileCount
             const parts: string[] = []
-            if (size !== undefined) parts.push(formatFileSize(size))
-            if (fileCount !== undefined) {
+            if (size != null) parts.push(formatFileSize(size))
+            if (fileCount != null) {
                 parts.push(`${formatNumber(fileCount)} ${fileCount === 1 ? 'file' : 'files'}`)
             }
             return parts.length > 0 ? parts.join('   ') : ''
         }
-        return item.size !== undefined ? formatFileSize(item.size) : ''
+        return item.size != null ? formatFileSize(item.size) : ''
     }
 </script>
 

apps/desktop/src/lib/file-operations/delete/delete-dialog-utils.ts

@@ -3,14 +3,16 @@
  * Pure functions — no Svelte reactivity, no side effects.
  */
 
-/** Minimal item info needed by DeleteDialog for display. */
+/** Minimal item info needed by DeleteDialog for display.
+ *  Group A wire-format: IPC sends `null` for absent FileEntry fields, not `undefined`.
+ *  Accept both so the constructed item shape matches whatever the caller passes through. */
 export interface DeleteSourceItem {
   name: string
-  size?: number
+  size?: number | null
   isDirectory: boolean
   isSymlink: boolean
-  recursiveSize?: number
-  recursiveFileCount?: number
+  recursiveSize?: number | null
+  recursiveFileCount?: number | null
 }
 
 /**