Users had to type an absolute server path on a phone keyboard to pick a
working directory (#49 "Choose project UIX"), and #57 reports that
only the default-drive project is ever discoverable. #52 already added
recents + client.project.list() as flat pickers, but there was still no
way to browse into subdirectories or discover paths the server hadn't
already indexed as a "project" — the only fallback was manual typing.
The opencode server already exposes a scoped filesystem-listing endpoint
(GET /file, handled in file.ts/handlers/file.ts) that resolves relative
to whatever directory the request is scoped to (header or query param) —
no new server endpoint is needed. Add file.list() to the mobile SDK
client and a new DirectoryBrowserSheet that lists subdirectories one
level at a time (via clientForDirectory(dir) + file.list({path: "."})),
supports "up" navigation, and a manual jump-to-path field. Wire it into
both the "new session" modal and the existing DirectorySwitcher, so
recents/manual entry remain available as a fallback alongside browsing.
Residual gap: there's still no "list available drives" API, so Windows
users with projects on D:, E:, etc. still need to type the drive root
once (it's then remembered via recents) — a full fix for #57 would need
a small server-side addition to enumerate mounted volumes.
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