Go to a folder by name, with g then o

Requested in #233. The `g` shortcuts cover the handful of folders every
account has -- inbox, sent, drafts -- and nothing reaches the dozens a Sieve
rule fills, which is where somebody with a real folder tree spends their time.
`g o` opens the picker, you type part of a name, and you are there.

The picker is the one the move action already uses, with one difference that
only shows up on shared mail: it selected folders by `mayAddItems`, which is
right for a destination and wrong for a place to go. A shared folder you may
read but not file into is somewhere you can visit. The right is now a
parameter, named for what it is asking rather than for which caller wants it.

Hosted in AppShell rather than in the mail view, because the `g` shortcuts are
global and the mail view is not mounted to hear about it -- pressing this from
the calendar should still take you to a folder, and now does.

`o` on its own opens a conversation and does not clash: a pending prefix is
tried before a bare key. That was already true and nothing said so, so there
are now five tests for the sequence machinery -- including that an abandoned
prefix costs the prefix and not the keystroke after it, which is the nicer
behaviour of the two and was undocumented.

Checked in a browser against the mock: opened from the calendar, filtered to a
nested folder, landed on it, and `o` still opened a conversation afterwards.

Closes #233.

web/src/views/AppShell.tsx

@@ -15,6 +15,7 @@ import { FilesTree } from "./files/FilesTree";
 import { ContactsSidebar } from "./contacts/ContactsSidebar";
 import { CalendarSidebar } from "./calendar/CalendarSidebar";
 import { ShortcutsDialog, useGlobalShortcuts } from "./Shortcuts";
+import { MailboxPicker } from "./mail/MailboxPicker";
 import { formatSize } from "@/lib/format";
 import { TranslateBoundary } from "@/ui/TranslateBoundary";
 import { t } from "@/lib/i18n";
@@ -37,9 +38,15 @@ export function AppShell({ children }: { children: ReactNode }) {
   const session = useSession((s) => s.session);
   const logout = useSession((s) => s.logout);
   const acctMenu = useMenu();
+  /*
+   * "Go to folder" (#233), hosted here rather than in the mail view because
+   * the `g` shortcuts are global: pressing it from the calendar should still
+   * take you to a folder, and the mail view is not mounted to hear about it.
+   */
+  const [goFolder, setGoFolder] = useState(false);
   const section = location.split("/")[1] || "mail";
 
-  useGlobalShortcuts({ onHelp: () => setHelpOpen(true) });
+  useGlobalShortcuts({ onHelp: () => setHelpOpen(true), onGoToFolder: () => setGoFolder(true) });
   useEffect(() => setDrawer(false), [location]);
 
   // Escape closes it too, for the tablet with a keyboard attached.
@@ -220,6 +227,16 @@ export function AppShell({ children }: { children: ReactNode }) {
         </>
       )}
       <ShortcutsDialog open={helpOpen} onClose={() => setHelpOpen(false)} />
+      {goFolder && (
+        <MailboxPicker
+          title={t("Go to folder…")}
+          /* Read, not write: a shared folder you may read but not file into is
+             still somewhere worth going. */
+          need="mayReadItems"
+          onClose={() => setGoFolder(false)}
+          onPick={(id) => { setGoFolder(false); navigate(`/mail/${id}`); }}
+        />
+      )}
     </div>
   );
 }

web/src/views/Shortcuts.tsx

@@ -7,7 +7,7 @@ import { Dialog } from "@/ui/dialog";
 import { Kbd } from "@/ui/misc";
 import { t } from "@/lib/i18n";
 
-export function useGlobalShortcuts({ onHelp }: { onHelp: () => void }) {
+export function useGlobalShortcuts({ onHelp, onGoToFolder }: { onHelp: () => void; onGoToFolder: () => void }) {
   const [, navigate] = useLocation();
   useEffect(() => {
     const go = (role: string) => () => {
@@ -18,6 +18,15 @@ export function useGlobalShortcuts({ onHelp }: { onHelp: () => void }) {
       { keys: "c", description: "Compose new message", group: "Mail", handler: () => void useCompose.getState().open() },
       { keys: "?", description: "Show keyboard shortcuts", group: "Navigation", handler: onHelp },
       { keys: "g i", description: "Go to Inbox", group: "Navigation", handler: go("inbox") },
+      /*
+       * A folder by name, for a tree the other `g` shortcuts cannot reach. The
+       * ones below are the handful of folders every account has; this is for
+       * the dozens that Sieve fills and that have no letter of their own (#233).
+       *
+       * `o` on its own opens a conversation, which is not a clash: the manager
+       * completes a pending sequence before it tries a single key.
+       */
+      { keys: "g o", description: "Go to folder…", group: "Navigation", handler: onGoToFolder },
       { keys: "g s", description: "Go to Starred", group: "Navigation", handler: () => navigate("/search?q=is:starred") },
       { keys: "g t", description: "Go to Sent", group: "Navigation", handler: go("sent") },
       { keys: "g d", description: "Go to Drafts", group: "Navigation", handler: go("drafts") },
@@ -27,7 +36,7 @@ export function useGlobalShortcuts({ onHelp }: { onHelp: () => void }) {
       { keys: "g f", description: "Go to Files", group: "Navigation", handler: () => navigate("/files") },
       { keys: "g k", description: "Go to Settings", group: "Navigation", handler: () => navigate("/settings") },
     ]);
-  }, [navigate, onHelp]);
+  }, [navigate, onHelp, onGoToFolder]);
 }
 
 export function ShortcutsDialog({ open, onClose }: { open: boolean; onClose: () => void }) {

web/src/views/mail/MailboxPicker.tsx

@@ -6,14 +6,22 @@ import type { Id, Mailbox } from "@/jmap/types";
 import { t } from "@/lib/i18n";
 import { mailboxDisplayPath } from "@/lib/mailboxName";
 
-export function MailboxPicker({ title, onClose, onPick, exclude }: { title: string; onClose: () => void; onPick: (id: Id) => void; exclude?: Id[] }) {
+/**
+ * @param need which right a folder has to grant to be worth offering.
+ *   `mayAddItems` for a move — a folder you cannot file into is not a
+ *   destination — and `mayReadItems` for going somewhere, since a shared
+ *   folder you may read but not write to is still somewhere you can go. The
+ *   distinction only shows up on shared mail, which is exactly where getting
+ *   it wrong would be invisible to whoever wrote the code.
+ */
+export function MailboxPicker({ title, onClose, onPick, exclude, need = "mayAddItems" }: { title: string; onClose: () => void; onPick: (id: Id) => void; exclude?: Id[]; need?: "mayAddItems" | "mayReadItems" }) {
   const mailboxes = useMail((s) => s.mailboxes);
   const mailboxPath = useMail((s) => s.mailboxPath);
   const [q, setQ] = useState("");
   const [active, setActive] = useState(0);
   const list = useMemo(() => {
     const all = Object.values(mailboxes)
-      .filter((m) => !exclude?.includes(m.id) && m.myRights.mayAddItems)
+      .filter((m) => !exclude?.includes(m.id) && m.myRights[need])
       .map((m) => ({ m, path: mailboxDisplayPath(m, mailboxes) }))
       .sort((a, b) => (a.m.role === "inbox" ? -1 : b.m.role === "inbox" ? 1 : a.path.localeCompare(b.path)));
     const ql = q.trim().toLowerCase();