Open a folder chip on its folder, in the folder that really holds it

A bot's folder chip went to bare /admin/files instead of the folder it
named, and even once there the computer volume pointed at the wrong
directory, so the folder a bot linked to looked empty.

The chip lost its folder because folderRefUrl only accepted a ref's
volume name (computer) while the chip hands it the browser's
(computers), so storageVolumeFromRef found nothing and the whole query
was dropped. Both spellings resolve now, through parseStorageSpec, so a
bad owner falls back cleanly instead of emitting owner=0.

The deeper bug: a computer's home was assumed to be
DATA_DIR/computers/<id>, but on a bind mount it can be anywhere on the
docker host, and a computer the app didn't provision (the main one on a
server reached at MAIN_COMPUTER_URL, i.e. a dev server outside docker)
records nothing at all. resolveComputerHomeDir holds the precedence:
the directory provisionComputer actually bound in
(containers.metadata.data_dir), else the new MAIN_COMPUTER_DATA_DIR app
setting for the main computer, else the conventional folder.

A path that isn't on disk also no longer reads as an empty folder:
listStorageEntries reports it as missing and the page says so, so a
stale folder link can't look like a folder nothing has written yet.

src/pages/admin/files/(functions)/folder-text.test.ts

@@ -0,0 +1,57 @@
+import { describe, expect, test } from "bun:test";
+import type { StorageFolderPayload } from "@/src/types";
+import { emptyFolderText, folderSummary } from "./folder-text";
+
+function folder(overrides: Partial<StorageFolderPayload> = {}): StorageFolderPayload {
+    return {
+        spec: { volume: "computers", owner_id: 1 },
+        label: "Main computer",
+        path: "seo/coderank",
+        breadcrumbs: [],
+        entries: [],
+        total: 0,
+        offset: 0,
+        ...overrides,
+    };
+}
+
+describe("folderSummary", () => {
+    test("counts what is in the folder", () => {
+        expect(folderSummary({ folder: folder({ total: 4 }) })).toContain("4 item(s)");
+    });
+
+    test("says a missing folder isn't on disk, not that it is empty", () => {
+        const text = folderSummary({ folder: folder({ missing: true }) });
+
+        expect(text).toContain("isn't on disk");
+        expect(text).not.toContain("0 item(s)");
+    });
+
+    test("asks for a folder when there is none", () => {
+        expect(folderSummary({ folder: null })).toBe("Pick a folder to look inside.");
+    });
+});
+
+describe("emptyFolderText", () => {
+    test("an empty folder says so", () => {
+        expect(emptyFolderText({ folder: folder(), search: "" })).toBe("This folder is empty.");
+    });
+
+    test("a path that isn't there says so instead", () => {
+        expect(emptyFolderText({ folder: folder({ missing: true }), search: "" })).toBe(
+            "There's no seo/coderank in here. It may have been moved or deleted.",
+        );
+    });
+
+    test("loading, an error and a search each win over the folder's own state", () => {
+        expect(emptyFolderText({ folder: folder({ missing: true }), search: "", loading: true })).toBe(
+            "Loading...",
+        );
+        expect(
+            emptyFolderText({ folder: folder({ missing: true }), search: "", error: "Not found." }),
+        ).toBe("Not found.");
+        expect(emptyFolderText({ folder: folder({ missing: true }), search: "raw" })).toBe(
+            'Nothing matches "raw".',
+        );
+    });
+});

src/pages/admin/files/(functions)/folder-text.ts

@@ -0,0 +1,42 @@
+import type { StorageFolderPayload } from "@/src/types";
+
+/**
+ * The line under the open folder's name: how much is in it, or, for a path
+ * that isn't on disk, that it isn't there. A stale folder link must never
+ * read as an empty folder.
+ */
+export function folderSummary({ folder }: { folder: StorageFolderPayload | null }) {
+    if (!folder) return "Pick a folder to look inside.";
+
+    if (folder.missing) {
+        return `${folder.label}: this folder isn't on disk. Nothing has written it yet, or its link is out of date.`;
+    }
+
+    return `${folder.label}: ${folder.total} item(s). Everything a bot, a workspace or a computer keeps for you.`;
+}
+
+/**
+ * What an empty listing says, and why it is empty when the folder the
+ * user asked for isn't there at all.
+ */
+export function emptyFolderText({
+    folder,
+    search,
+    loading,
+    error,
+}: {
+    folder: StorageFolderPayload | null;
+    search: string;
+    loading?: boolean;
+    error?: string;
+}) {
+    if (loading) return "Loading...";
+    if (error) return error;
+    if (search) return `Nothing matches "${search}".`;
+
+    if (folder?.missing) {
+        return `There's no ${folder.path || "folder"} in here. It may have been moved or deleted.`;
+    }
+
+    return "This folder is empty.";
+}

src/pages/admin/files/(sections)/files-browser.tsx

@@ -4,6 +4,7 @@ import Span from "@moduletrace/twui/layout/Span";
 import Stack from "@moduletrace/twui/layout/Stack";
 import type { StorageFolderPayload, StorageSpecOption } from "@/src/types";
 import type { StorageSpec } from "@/src/utils/storage-volumes";
+import { emptyFolderText, folderSummary } from "../(functions)/folder-text";
 import FilesBreadcrumbRow from "../(partials)/files-breadcrumb-row";
 import FilesSearchInput from "../(partials)/files-search-input";
 import FilesVolumeRow from "../(partials)/files-volume-row";
@@ -81,9 +82,7 @@ export default function FilesBrowser({
                                 "Files"}
                         </H2>
                         <Span className="text-[13px] leading-[18px] text-ink-secondary">
-                            {folder
-                                ? `${folder.label}: ${folder.total} item(s). Everything a bot, a workspace or a computer keeps for you.`
-                                : "Pick a folder to look inside."}
+                            {folderSummary({ folder })}
                         </Span>
                     </Stack>
                     <FilesBreadcrumbRow
@@ -111,12 +110,7 @@ export default function FilesBrowser({
                             ))
                         ) : (
                             <Span className="py-8 text-[13px] leading-[18px] text-ink-secondary">
-                                {loading
-                                    ? "Loading..."
-                                    : error ||
-                                      (search
-                                          ? `Nothing matches "${search}".`
-                                          : "This folder is empty.")}
+                                {emptyFolderText({ folder, search, loading, error })}
                             </Span>
                         )}
                     </Stack>

src/pages/admin/files/index.server.ts

@@ -80,5 +80,6 @@ async function folderPayload({
         entries: listing.entries,
         total: listing.total,
         offset: listing.offset,
+        missing: listing.missing,
     };
 }