feat(host): directory-picker capability seam with dialog and browse backends

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

scripts/gen-cordis-catalog.ts

@@ -226,6 +226,7 @@ const TYPE_LINK_EXEMPTIONS: Readonly<Record<string, string>> = {
   BashEnvContributor: 'service-local extension type is owned by packages/bash/tool-bash/src/index.ts',
   BashEnvVariableInfo: 'service-local metadata type is owned by packages/bash/tool-bash/src/index.ts',
   CompactAgentContext: 'compaction service input is owned by packages/compact/compact/src/index.ts',
+  DirectoryPickerCapability: 'picker interaction contract is owned by packages/host/directory-picker/README.md',
   CreateAgentOptions: 'agent creation contract is owned by packages/core/agent/README.md',
   Domain: 'domain interface is owned by packages/storage/storage-domain/README.md',
   DomainChanged: 'event-local snapshot is owned by packages/storage/storage-domain/src/events.ts',

scripts/gen-doc-graphs.ts

@@ -408,6 +408,15 @@ const SERVICE_ROLES: ServiceRole[] = [
     consumers: ['spill-policy'],
     note: 'The backend saves oversized tool text and returns a model-facing locator plus retrieval hint; spill-policy is the tools/post-execute consumer that decides when to spill.',
   },
+  {
+    key: 'directoryPicker',
+    pkg: 'directory-picker',
+    title: 'Workspace-directory picking seam',
+    mode: 'seam',
+    implementations: ['directory-picker-dialog', 'directory-picker-browse'],
+    consumers: ['apiproxy'],
+    note: 'Discriminated interaction capability: the dialog backend opens one native OS chooser on the host display, the browse backend serves listing/creation primitives for the in-app browser; the gateway advertises the kind via host.describe.',
+  },
   {
     key: 'httpServer',
     pkg: 'webserver',

scripts/verify-package-readme-model-experience.ts

@@ -73,6 +73,9 @@ const SENTENCE_MODEL_EXPERIENCE: Readonly<Record<string, SentenceContract>> = {
   'packages/fs/fs-sandbox': { kind: 'indirect', reason: 'The provider backend delegates model rendering to dsh-tool-fs.' },
   'packages/hooks/hook-protocol': { kind: 'indirect', reason: 'Only the hook bridge plugins render decoded hook output to a model.' },
   'packages/host/apiproxy': { kind: 'none', reason: 'The wire contract and fetch carriers move already-composed messages and register no model surface.' },
+  'packages/host/directory-picker': { kind: 'none', reason: 'The GUI-host picking seam registers no model surface.' },
+  'packages/host/directory-picker-browse': { kind: 'none', reason: 'The GUI-host picking backend registers no model surface.' },
+  'packages/host/directory-picker-dialog': { kind: 'none', reason: 'The GUI-host picking backend registers no model surface.' },
   'packages/host/webserver': { kind: 'none', reason: 'The HTTP carrier bridges browser and API handler and registers no model surface.' },
   'packages/llm/llm': { kind: 'none', reason: 'The adapter registry forwards already-assembled requests unchanged.' },
   'packages/llm/token-meter': { kind: 'indirect', reason: 'The measurement service leaves model-visible changes to its consumers.' },