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

docs/capability-seams.md

@@ -136,6 +136,10 @@ flowchart LR
   svc_spillStore["ctx.spillStore<br/>Spill storage seam"]
   pkg_spill_local["spill-local"]
   pkg_spill_policy["spill-policy"]
+  pkg_directory_picker["directory-picker"]
+  svc_directoryPicker["ctx.directoryPicker<br/>Workspace-directory picking seam"]
+  pkg_directory_picker_dialog["directory-picker-dialog"]
+  pkg_directory_picker_browse["directory-picker-browse"]
   pkg_webserver["webserver"]
   svc_httpServer["ctx.httpServer<br/>HTTP route registration"]
   pkg_connection["connection"]
@@ -159,6 +163,9 @@ flowchart LR
   pkg_compact --> svc_compact
   pkg_compact_basic --> svc_compact
   pkg_compact_tool_result_prune --> svc_toolResultPrune
+  pkg_directory_picker --> svc_directoryPicker
+  pkg_directory_picker_browse --> svc_directoryPicker
+  pkg_directory_picker_dialog --> svc_directoryPicker
   pkg_fs --> svc_fs
   pkg_fs_local --> svc_fs
   pkg_fs_sandbox --> svc_fs
@@ -235,6 +242,7 @@ flowchart LR
   svc_codeRuntime --> pkg_tools
   svc_commands --> pkg_tui
   svc_compact --> pkg_compact_basic
+  svc_directoryPicker --> pkg_apiproxy
   svc_fs --> pkg_tool_fs
   svc_httpServer --> pkg_connection
   svc_httpServer --> pkg_hmr
@@ -348,6 +356,7 @@ flowchart LR
 | `ctx.tasks` | `seam` | [`tasks`](../packages/tasks/tasks) | [`tasks-local`](../packages/tasks/tasks-local) | [`tool-bash`](../packages/bash/tool-bash), [`tool-pty`](../packages/pty/tool-pty), [`tool-subagent`](../packages/subagent/tool-subagent), [`tool-tasks`](../packages/tasks/tool-tasks) | - | Producers (background bash, PTY sends, and subagent delegations) register running work; tool-tasks is the model-facing control surface that reads, lists, and kills it; tasks-local is the process-local registry. |
 | `ctx.web` | `seam` | [`web`](../packages/web/web) | [`web-search-exa`](../packages/web/web-search-exa), [`web-search-perplexity`](../packages/web/web-search-perplexity), [`web-search-deepseek`](../packages/web/web-search-deepseek), [`web-fetch-local`](../packages/web/web-fetch-local) | [`tool-web`](../packages/web/tool-web) | - | Search and fetch providers register into one ctx.web seam; tool-web owns the stable model-facing names. |
 | `ctx.spillStore` | `seam` | [`spill`](../packages/spill/spill) | [`spill-local`](../packages/spill/spill-local) | [`spill-policy`](../packages/spill/spill-policy) | - | 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. |
+| `ctx.directoryPicker` | `seam` | `directory-picker` | `directory-picker-dialog`, `directory-picker-browse` | `apiproxy` | - | 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. |
 | `ctx.httpServer` | `core` | `webserver` | - | `connection`, `modules`, `hmr` | - | Plain node:http carrier: named-route registry, index transform taps, and the static dist fallback; web-transport plugins register their own routes. |
 | `ctx.clientModuleHost` | `core` | `modules` | - | `hmr` | - | Composes the __DSH_BOOT__ entry graph from an incremental dshClient scan, serves plugin bundles, and notifies rebuilt/graph-changed subscribers. |
 | `ctx.workflows` | `seam` | [`workflow`](../packages/workflow/workflow) | [`workflow-workerthread`](../packages/workflow/workflow-workerthread) | [`tool-workflow`](../packages/workflow/tool-workflow), [`tool-ralph`](../packages/workflow/tool-ralph) | - | One engine per context (bash shape, no named-provider registry); the general workflow and fixed Ralph consumers start runs whose agent() calls fan out through ctx.subagents. |

docs/config-catalog.md

@@ -505,7 +505,7 @@ Source: [`packages/hooks/hooks-codex/src/index.ts:43`](../packages/hooks/hooks-c
 
 ## `@deepseek-ai/dsh-host-apiproxy`
 
-Requires: `agents` · `llm` · `sessions` · `tools` · `userInteraction` · `workspace`
+Requires: `agents` · `directoryPicker` · `llm` · `sessions` · `tools` · `userInteraction` · `workspace`
 
 ```ts config-catalog
 /** Gateway plugin config: host-level agent routing and Workspace creation root. */
@@ -2184,6 +2184,8 @@ These load from a `cordis.yml` entry with no `config:` block; they declare no co
 - `@deepseek-ai/dsh-commands` ([`packages/ui/commands/src/index.ts`](../packages/ui/commands/src/index.ts))
 - `@deepseek-ai/dsh-fs-policy` ([`packages/fs/fs-policy/src/index.ts`](../packages/fs/fs-policy/src/index.ts))
 - `@deepseek-ai/dsh-goal-session` — requires `agents` · `goals` · `sessions` ([`packages/goal/goal-session/src/index.ts`](../packages/goal/goal-session/src/index.ts))
+- `@deepseek-ai/dsh-host-directory-picker-browse` ([`packages/host/directory-picker-browse/src/index.ts`](../packages/host/directory-picker-browse/src/index.ts))
+- `@deepseek-ai/dsh-host-directory-picker-dialog` ([`packages/host/directory-picker-dialog/src/index.ts`](../packages/host/directory-picker-dialog/src/index.ts))
 - `@deepseek-ai/dsh-llm` ([`packages/llm/llm/src/index.ts`](../packages/llm/llm/src/index.ts))
 - `@deepseek-ai/dsh-lsp` ([`packages/lsp/lsp/src/index.ts`](../packages/lsp/lsp/src/index.ts))
 - `@deepseek-ai/dsh-pty` ([`packages/pty/pty/src/index.ts`](../packages/pty/pty/src/index.ts))
@@ -2230,6 +2232,7 @@ Imported as libraries by other packages; a `cordis.yml` cannot load them.
 - `@deepseek-ai/dsh-client-web-react` ([`packages/client/web-react/src/index.ts`](../packages/client/web-react/src/index.ts))
 - `@deepseek-ai/dsh-helper` ([`packages/sdk/helper/src/index.ts`](../packages/sdk/helper/src/index.ts))
 - `@deepseek-ai/dsh-hook-protocol` ([`packages/hooks/hook-protocol/src/index.ts`](../packages/hooks/hook-protocol/src/index.ts))
+- `@deepseek-ai/dsh-host-directory-picker` ([`packages/host/directory-picker/src/index.ts`](../packages/host/directory-picker/src/index.ts))
 - `@deepseek-ai/dsh-jsonrpc-demo` ([`packages/examples/jsonrpc-demo/src/index.ts`](../packages/examples/jsonrpc-demo/src/index.ts))
 - `@deepseek-ai/dsh-llm-mock-server` ([`packages/support/llm-mock-server/src/index.ts`](../packages/support/llm-mock-server/src/index.ts))
 - `@deepseek-ai/dsh-loader-smoke` ([`packages/support/loader-smoke/src/index.ts`](../packages/support/loader-smoke/src/index.ts))

docs/cordis-catalog/services.md

@@ -469,6 +469,20 @@ Types: [CompactionResult](../core-data-structures/compaction.md) · [CompactionT
 
 Source: [`packages/compact/compact/src/index.ts:54`](../../packages/compact/compact/src/index.ts)
 
+## `ctx.directoryPicker` — `DirectoryPicker` (abstract seam)
+
+Abstract directory-picking service. Subclass, implement `capability()`, and load the subclass as a plugin — it registers as `ctx.directoryPicker` (one implementation per context; loading a second throws, cordis' standard duplicate-service behavior). The capability object must be stable for the service lifetime: consumers may capture it across calls.
+
+```ts cordis-catalog
+/**
+ * The backend's interaction capability.
+ * @returns the discriminated capability consumers switch on.
+ */
+abstract capability(): DirectoryPickerCapability
+```
+
+Source: [`packages/host/directory-picker/src/index.ts:108`](../../packages/host/directory-picker/src/index.ts)
+
 ## `ctx.fs` — `FileSystem` (abstract seam)
 
 Abstract filesystem provider. Targets must preserve identity across aliases; reads expose regular UTF-8 text or typed errors, listings are stable and content-free, and mutations are atomic. Optional guards add stale protection without changing the unguarded provider contract.

docs/module-graph.md

@@ -182,6 +182,9 @@ flowchart TD
   end
   subgraph group_host["packages/host"]
     pkg_host_apiproxy["host-apiproxy"]
+    pkg_host_directory_picker["host-directory-picker"]
+    pkg_host_directory_picker_browse["host-directory-picker-browse"]
+    pkg_host_directory_picker_dialog["host-directory-picker-dialog"]
     pkg_host_webserver["host-webserver"]
   end
   subgraph group_lsp["packages/lsp"]
@@ -257,6 +260,9 @@ flowchart TD
   pkg_code_runtime --> pkg_invariants
   pkg_jsonrpc_demo --> pkg_invariants
   pkg_host_apiproxy --> pkg_invariants
+  pkg_host_directory_picker --> pkg_invariants
+  pkg_host_directory_picker_browse --> pkg_invariants
+  pkg_host_directory_picker_dialog --> pkg_invariants
   pkg_host_webserver --> pkg_invariants
   pkg_storage --> pkg_invariants
   pkg_subprocess --> pkg_invariants
@@ -924,6 +930,9 @@ flowchart TD
 | [`code-runtime`](../packages/code-runtime/code-runtime) | `code-runtime` | [`invariants`](../packages/support/invariants) |
 | [`jsonrpc-demo`](../packages/examples/jsonrpc-demo) | `examples` | [`invariants`](../packages/support/invariants) |
 | [`host-apiproxy`](../packages/host/apiproxy) | `host` | [`invariants`](../packages/support/invariants) |
+| [`host-directory-picker`](../packages/host/directory-picker) | `host` | [`invariants`](../packages/support/invariants) |
+| [`host-directory-picker-browse`](../packages/host/directory-picker-browse) | `host` | [`invariants`](../packages/support/invariants) |
+| [`host-directory-picker-dialog`](../packages/host/directory-picker-dialog) | `host` | [`invariants`](../packages/support/invariants) |
 | [`host-webserver`](../packages/host/webserver) | `host` | [`invariants`](../packages/support/invariants) |
 | [`storage`](../packages/storage/storage) | `storage` | [`invariants`](../packages/support/invariants) |
 | [`subprocess`](../packages/subprocess/subprocess) | `subprocess` | [`invariants`](../packages/support/invariants) |