The web GUI's folder picking was hardwired to one interaction: a native OS chooser compiled into the gateway, unusable for remote deployments and swappable only by editing apiproxy source. Directory picking becomes a three-package capability seam in packages/host: ctx.directoryPicker returns a discriminated capability — dialog (the extracted native chooser; host-display only) or browse (new: one-level listing + child creation over Node stdlib, hidden flags host-stamped, symlinks followed, ancestry crumbs; remote-capable). The gateway injects the seam, advertises the kind via host.describe.directoryPicker, serves host.listDirectory / host.createDirectory under browse, and answers directory-picker-unavailable across kinds. cordis.yml is the swap point; apps/cli keeps dialog mounted, so behavior is unchanged until the in-app browser PR flips the default. The connection fixture serves a deterministic browse tree; WorkspacesService gains the browse calls the browser UI will drive. Decision record: .agents/notes/implemented/architecture/2026-07-28-directory-picker-capability-seam.md
@deepseek-ai/dsh-host-directory-picker
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The workspace-directory picking seam for the web-GUI host: an abstract DirectoryPicker service (ctx.directoryPicker) whose single contract method capability() returns a discriminated capability describing how an operator selects a directory. Backends differ in interaction shape, not just mechanism, so the seam models the shapes explicitly instead of one method set: { kind: 'dialog', pick(signal) } opens one native OS chooser on the host display (-dialog); { kind: 'browse', list(path?), createDirectory(path, name) } serves listing/creation primitives an in-app browser drives, which works for remote clients no OS dialog can reach (-browse). Consumers switch on capability().kind; the union is merge-extensible and the documented default for an unknown kind is to hide the picking affordance rather than fail. The capability object must be stable for the service lifetime.
Browse primitives fail with the typed DirectoryPickerError (directory-unreadable / directory-exists / directory-create-failed, each carrying the subject path), which the consuming gateway maps 1:1 onto wire error codes. DirectoryEntry rows carry a host-owned hidden flag (POSIX dot convention) so display policy stays client-side; DirectoryListing.crumbs is the ancestor chain from the filesystem root, every crumb a jump target. Design rationale, the ctx.fs separation, and the policy decisions live in the directory-picker capability seam Agent Note.
Model Experience
None, as the seam serves the GUI host's directory selection; nothing here reaches a model request.
KV Cache effect
None; this package neither assembles nor sends a provider request.
Known Limitations and Deferred Work
- No multi-root vocabulary — the browse contract exposes one ancestry chain per listing; per-deployment root scoping (and Windows drive-root enumeration above a drive) waits for a consumer that needs it, per the seam Agent Note.