Extract folder workspace diff comments to dedicated module

Moves normalizeFolderWorkspaceDiffComments and
collectFolderWorkspaceDiffComments from persistence.ts to a new
folder-workspace-diff-comments.ts module for better code organization.

src/main/folder-workspace-diff-comments.ts

@@ -0,0 +1,37 @@
+import type { DiffComment, FolderWorkspace } from '../shared/types'
+
+// Why shape-only: this replaces folder-workspaces.ts's verbatim `Array.isArray(raw.diffComments)` read.
+// Filtering members would make the fix itself a new deletion path for user-authored prose.
+export function normalizeFolderWorkspaceDiffComments(
+  value: unknown
+): Record<string, DiffComment[]> | undefined {
+  if (typeof value !== 'object' || value === null || Array.isArray(value)) {
+    return undefined
+  }
+  const normalized: Record<string, DiffComment[]> = {}
+  let kept = false
+  for (const [id, comments] of Object.entries(value)) {
+    if (!Array.isArray(comments)) {
+      continue
+    }
+    normalized[id] = comments as DiffComment[]
+    kept = true
+  }
+  return kept ? normalized : undefined
+}
+
+// Why derive on every write: the map self-GCs, so delete paths need no pruning code.
+export function collectFolderWorkspaceDiffComments(
+  workspaces: readonly FolderWorkspace[] | undefined
+): Record<string, DiffComment[]> | undefined {
+  const collected: Record<string, DiffComment[]> = {}
+  let kept = false
+  for (const workspace of workspaces ?? []) {
+    const comments = workspace.diffComments
+    if (Array.isArray(comments) && comments.length > 0) {
+      collected[workspace.id] = comments
+      kept = true
+    }
+  }
+  return kept ? collected : undefined
+}

src/main/persistence.ts

@@ -55,7 +55,6 @@ import type {
   Repo,
   ProjectGroup,
   FolderWorkspace,
-  DiffComment,
   SparsePreset,
   PersistedMobileClientTabSelections,
   WorktreeMeta,
@@ -257,6 +256,10 @@ import { normalizeUiLanguage } from '../shared/ui-language'
 import { normalizeBrowserPageZoomLevel } from '../shared/browser-page-zoom'
 import { persistedUIValuesEqual } from '../shared/persisted-ui-equality'
 import { ActiveViewPreference } from './active-view-preference'
+import {
+  collectFolderWorkspaceDiffComments,
+  normalizeFolderWorkspaceDiffComments
+} from './folder-workspace-diff-comments'
 import {
   normalizeFolderWorkspaceName,
   normalizeFolderWorkspaces
@@ -429,42 +432,6 @@ function gcStaleWorktreeMeta(state: PersistedState): number {
   return removed
 }
 
-// Why shape-only: this replaces folder-workspaces.ts's verbatim `Array.isArray(raw.diffComments)` read.
-// Filtering members would make the fix itself a new deletion path for user-authored prose.
-function normalizeFolderWorkspaceDiffComments(
-  value: unknown
-): Record<string, DiffComment[]> | undefined {
-  if (typeof value !== 'object' || value === null || Array.isArray(value)) {
-    return undefined
-  }
-  const normalized: Record<string, DiffComment[]> = {}
-  let kept = false
-  for (const [id, comments] of Object.entries(value)) {
-    if (!Array.isArray(comments)) {
-      continue
-    }
-    normalized[id] = comments as DiffComment[]
-    kept = true
-  }
-  return kept ? normalized : undefined
-}
-
-// Why derive on every write: the map self-GCs, so delete paths need no pruning code.
-function collectFolderWorkspaceDiffComments(
-  workspaces: readonly FolderWorkspace[] | undefined
-): Record<string, DiffComment[]> | undefined {
-  const collected: Record<string, DiffComment[]> = {}
-  let kept = false
-  for (const workspace of workspaces ?? []) {
-    const comments = workspace.diffComments
-    if (Array.isArray(comments) && comments.length > 0) {
-      collected[workspace.id] = comments
-      kept = true
-    }
-  }
-  return kept ? collected : undefined
-}
-
 function normalizeWorktreeLinkedItemMetadata(state: PersistedState): boolean {
   let changed = false
   const rawWorktreeMeta = state.worktreeMeta as unknown