@@ -7,30 +7,26 @@ import type {
 } from '@/app/workspace/[workspaceId]/components/resource/components/resource-header'
 
 /**
- * The only thing a breadcrumb trail needs from a folder tree node. Structural rather than
- * `WorkflowFolder` so the Files tree builds its trail through this same code path instead of
- * forking one: file folders live in the same `folder` table, but they are served by their own
- * routes and carry their own row type (see the `servedFolderResourceTypeSchema` docs in
- * `@/lib/api/contracts/folders` for why that split exists and is staying).
+ * Structural rather than `WorkflowFolder` so the Files tree — same `folder` table, own routes
+ * and row type (see `servedFolderResourceTypeSchema` in `@/lib/api/contracts/folders`) — shares
+ * this code path instead of forking it.
  */
 export interface BreadcrumbFolder {
   id: string
   name: string
   parentId: string | null
 }
 
+const EMPTY_CHAIN: never[] = []
+
 /**
- * Root-first ancestor chain for a breadcrumb trail, that folder last. Empty at the workspace
- * root — and empty for a chain that does not reach the root, where {@link folderAncestorChain}
- * would hand back the part it walked.
- *
- * A header falls back to the root title rather than rendering a trail that silently skips a
- * level: a partial path is not a shorter path, it is a wrong one, claiming the deepest folder
- * it resolved sits at the workspace root. A chain is complete exactly when its first element
- * has no parent, which also rejects a cycle (the DB permits one between constraint checks).
+ * Root-first ancestor chain, that folder last, or empty when it does not reach the root —
+ * where {@link folderAncestorChain} would hand back the part it walked.
  *
- * `folderById` must therefore be the complete tree — see `FolderAncestors.foldersResolved`;
- * a partially loaded map reads as an orphan and collapses.
+ * A partial path is not a shorter path, it is a wrong one: it claims the deepest folder it
+ * resolved sits at the workspace root. Falling back to the root title is the honest render.
+ * Completeness is `chain[0].parentId === null`, which also rejects a cycle. Callers must pass
+ * the complete tree — see `FolderAncestors.foldersResolved`.
  */
 export function breadcrumbFolderChain<T extends BreadcrumbFolder>(
   folderId: string | null | undefined,
@@ -40,10 +36,8 @@ export function breadcrumbFolderChain<T extends BreadcrumbFolder>(
   return chain.length === 0 || chain[0].parentId === null ? chain : EMPTY_CHAIN
 }
 
-const EMPTY_CHAIN: never[] = []
-
 interface FolderBreadcrumbItemsBase {
-  /** Root crumb label — the page's own name ("Knowledge Base", "Tables"). */
+  /** Root crumb label — the page's own name ("Knowledge bases", "Tables"). */
   rootLabel: string
   rootIcon?: ElementType
   /** Root-first ancestor chain, from {@link folderAncestorChain}. */
@@ -84,17 +78,13 @@ export type FolderBreadcrumbItemsOptions =
 const NO_TRAILING_CRUMBS: BreadcrumbItem[] = []
 
 /**
- * Converts a folder ancestor chain into the `BreadcrumbItem[]` that `Resource.Header`
- * renders, for a list page (`Tables / Reports`) or a detail page (`Tables / Reports / Q3`).
+ * Builds the `BreadcrumbItem[]` for a list page (`Tables / Reports`) or a detail page
+ * (`Tables / Reports / Q3`).
  *
  * A plain builder rather than a component: `Resource.Header` already owns every piece of
  * breadcrumb chrome — the root-crumb "Path" popover, segment width allocation, overflow
- * tooltips, and the rule that a single-element trail renders as a plain page title. A
- * sibling crumb component would have to fork all of it, which is exactly what this shared
- * directory exists to prevent.
- *
- * The trail always starts with the root crumb, so a list page at the workspace root returns
- * length 1 and the header renders the page title unchanged.
+ * tooltips, and the rule that a single-element trail renders as a plain page title. A sibling
+ * crumb component would have to fork all of it, which is what this directory exists to prevent.
  */
 export function folderBreadcrumbItems(options: FolderBreadcrumbItemsOptions): BreadcrumbItem[] {
   const { rootLabel, rootIcon, breadcrumbs, onNavigate } = options
 
@@ -25,10 +25,9 @@ export interface FolderedResourceHeaderMeta {
 /**
  * The per-resource facts a foldered header needs, in one place.
  *
- * Each of these was previously restated at every surface that renders the resource — the list
- * page, the detail page, and (for knowledge bases) the document and chunk views — which is how
- * the same trail ends up with a different label or icon depending on which page you reached it
- * from. Adding a foldered resource is an entry here plus its pages, never a fifth literal.
+ * Each was previously restated at every surface rendering that resource — list page, detail
+ * page, and for knowledge bases the document and chunk views — which is how one trail ends up
+ * labelled differently depending on which page you reached it from.
  */
 export const FOLDERED_RESOURCE_HEADERS: Record<
   FolderedHeaderResourceType,
 
@@ -7,38 +7,20 @@ import {
   folderNavParsers,
   folderNavUrlKeys,
 } from '@/app/workspace/[workspaceId]/components/folders/search-params'
-import { useFolderAncestors } from '@/app/workspace/[workspaceId]/components/folders/use-folder-ancestors'
-import type { WorkflowFolder } from '@/stores/folders/types'
+import {
+  type FolderAncestors,
+  useFolderAncestors,
+} from '@/app/workspace/[workspaceId]/components/folders/use-folder-ancestors'
 
 export interface UseFolderNavigationOptions {
   resourceType: ServedFolderResourceType
   workspaceId?: string
 }
 
-export interface FolderNavigation {
+export interface FolderNavigation extends FolderAncestors {
   /** The open folder, or `null` at the workspace root. */
   currentFolderId: string | null
   setCurrentFolderId: (folderId: string | null) => void
-  /**
-   * Root-first ancestor chain of the open folder, the open folder last. Empty at the root,
-   * and empty while the folder list is still loading or when the id no longer resolves (a
-   * deleted folder or a stale bookmark) — callers fall back to the root listing rather than
-   * rendering a broken trail.
-   */
-  breadcrumbs: WorkflowFolder[]
-  /** Every active folder in this resource's tree, as returned by the folders API. */
-  folders: WorkflowFolder[]
-  folderById: Map<string, WorkflowFolder>
-  /**
-   * Whether `folders`/`folderById` can be trusted to be the COMPLETE set for this workspace.
-   *
-   * Deliberately exposed instead of `isLoading`, which is a footgun here: it is false for a
-   * disabled query (no `workspaceId`), false for an errored one, and — because `useFolders`
-   * sets `keepPreviousData` — false while the previous workspace's folders are still on screen
-   * during a switch. A caller deciding "this resource's `folderId` does not resolve, so treat it
-   * as an orphan" off `isLoading` would dump every foldered row at the root in all three.
-   */
-  foldersResolved: boolean
 }
 
 /**
@@ -59,11 +41,12 @@ export function useFolderNavigation({
     folderNavUrlKeys
   )
 
-  const { ancestors, folders, folderById, foldersResolved } = useFolderAncestors({
+  const ancestry = useFolderAncestors({
     resourceType,
     workspaceId,
     folderId: currentFolderId,
   })
+  const { folderById, foldersResolved } = ancestry
 
   const setCurrentFolderId = useCallback(
     (folderId: string | null) => {
@@ -96,12 +79,5 @@ export function useFolderNavigation({
     void setFolderParams({ folderId: null }, { history: 'replace' })
   }, [foldersResolved, currentFolderId, folderById, setFolderParams])
 
-  return {
-    currentFolderId,
-    setCurrentFolderId,
-    breadcrumbs: ancestors,
-    folders,
-    folderById,
-    foldersResolved,
-  }
+  return { ...ancestry, currentFolderId, setCurrentFolderId }
 }
@@ -1744,15 +1744,12 @@ export function Files() {
   )
 
   /**
-   * The trail while a file's content loads. Reuses the open folder from the URL, so arriving
-   * from a list page inside `A/B` holds `Files / A / B / …` instead of collapsing to
-   * `Files / …` and jumping back out once the file lands. A cold deep-link carries no
-   * `?folderId=`, and the file whose folder it would name has not loaded yet, so that case
-   * still starts at the root.
+   * The trail while a file's content loads. Holds the URL's open folder so arriving from a
+   * list page inside `A/B` doesn't collapse to `Files / …` and jump back out once the file
+   * lands; a cold deep-link has no `?folderId=` and no loaded file, so it starts at the root.
    *
-   * Rendered only on the file *detail* route, so its folder crumbs leave this path through
-   * the router exactly as {@link fileDetailBreadcrumbs} does — the nuqs setter would append
-   * `?folderId=` to the still-open file's own URL and go nowhere.
+   * Renders on the file *detail* route, so its crumbs navigate through the router like
+   * {@link fileDetailBreadcrumbs} — a nuqs write would only requery this file's own URL.
    */
   const loadingBreadcrumbs = useMemo(
     (): BreadcrumbItem[] =>
 
@@ -135,7 +135,7 @@ export function Document({
   knowledgeBaseName,
   documentName,
 }: DocumentProps) {
-  const { workspaceId } = useParams()
+  const workspaceId = useParams().workspaceId as string
   const router = useRouter()
   const [
     {
@@ -154,7 +154,7 @@ export function Document({
   /** The base's folder trail, so this route's header matches the base's and the list's. */
   const { ancestors: folderChain } = useFolderAncestors({
     resourceType: 'knowledge_base',
-    workspaceId: workspaceId as string,
+    workspaceId,
     folderId: knowledgeBase?.folderId,
   })
 
@@ -504,14 +504,12 @@ export function Document({
   )
 
   /**
-   * Confirms before a crumb navigates away from an unsaved chunk. A route change unmounts the
-   * editor, so the edit is gone with no way back — the same reason the in-page transitions go
-   * through {@link guardDirtyAction}.
+   * Confirms before a crumb navigates away from an unsaved chunk — a route change unmounts the
+   * editor, so the edit is gone with no way back.
    *
-   * Gated on the editor actually being open, not on `isDirty` alone: `UnsavedChangesModal`
-   * mounts only alongside the editor, and `isDirty` outlives it when the editor is unmounted
-   * by a URL change rather than by `closeEditor` (browser Back off an edited chunk). Guarding
-   * unconditionally would then raise a modal nothing renders, leaving the crumb dead.
+   * Gated on the editor being open rather than on `isDirty` alone: `UnsavedChangesModal` mounts
+   * only alongside the editor, but `isDirty` outlives a URL-driven unmount (browser Back off an
+   * edited chunk), where guarding would raise a modal nothing renders and deaden the crumb.
    */
   const guardRouteChange = useCallback(
     (navigate: () => void) => {
@@ -524,7 +522,7 @@ export function Document({
   const handleNavToFolder = useCallback(
     (folderId: string | null) => {
       guardRouteChange(() =>
-        router.push(folderedResourceListHref('knowledge_base', workspaceId as string, folderId))
+        router.push(folderedResourceListHref('knowledge_base', workspaceId, folderId))
       )
     },
     [guardRouteChange, router, workspaceId]
 
@@ -203,11 +203,17 @@ export function Knowledge() {
   const { mutateAsync: updateKnowledgeBaseMutation } = useUpdateKnowledgeBase(workspaceId)
   const { mutateAsync: deleteKnowledgeBaseMutation } = useDeleteKnowledgeBase(workspaceId)
 
-  const { currentFolderId, setCurrentFolderId, breadcrumbs, folders, folderById, foldersResolved } =
-    useFolderNavigation({
-      resourceType: FOLDER_RESOURCE_TYPE,
-      workspaceId,
-    })
+  const {
+    currentFolderId,
+    setCurrentFolderId,
+    ancestors: breadcrumbs,
+    folders,
+    folderById,
+    foldersResolved,
+  } = useFolderNavigation({
+    resourceType: FOLDER_RESOURCE_TYPE,
+    workspaceId,
+  })
 
   const createFolder = useCreateFolder()
   const updateFolder = useUpdateFolder()
 
@@ -134,7 +134,7 @@ export function Tables() {
   const {
     currentFolderId,
     setCurrentFolderId,
-    breadcrumbs: folderChain,
+    ancestors: folderChain,
     folders,
     folderById,
     foldersResolved,