fix(desktop): route composer context picking through remote-aware fs

Second pass on the remote-project flow: the project dialog and git cockpit were
remote-aware, but the composer's Add file/folder context picker still called the
native Electron picker directly. Route it through selectDesktopPaths so remote
sessions use the backend-aware picker instead of local disk paths; preserve local
multi-select behavior and keep remote folder selection single because the in-app
remote picker only supports one directory.

Also use readDesktopFileDataUrl for image previews so an already-known backend
image path can be read through /api/fs/read-data-url, and add focused coverage
for backend file-diff routing plus the plain-folder git init/worktree path.

apps/desktop/src/app/chat/hooks/use-composer-actions.ts

@@ -5,6 +5,7 @@ import { droppedFileInlineRef } from '@/app/chat/composer/inline-refs'
 import { formatRefValue } from '@/components/assistant-ui/directive-text'
 import { useI18n } from '@/i18n'
 import { attachmentId, contextPath, pathLabel } from '@/lib/chat-runtime'
+import { isDesktopFsRemoteMode, readDesktopFileDataUrl, selectDesktopPaths } from '@/lib/desktop-fs'
 import {
   addComposerAttachment,
   type ComposerAttachment,
@@ -262,10 +263,11 @@ export function useComposerActions({ activeSessionId, currentCwd, requestGateway
 
   const pickContextPaths = useCallback(
     async (kind: 'file' | 'folder') => {
-      const paths = await window.hermesDesktop?.selectPaths({
+      const paths = await selectDesktopPaths({
         title: kind === 'file' ? 'Add files as context' : 'Add folders as context',
         defaultPath: currentCwd || undefined,
-        directories: kind === 'folder'
+        directories: kind === 'folder',
+        multiple: kind === 'folder' && isDesktopFsRemoteMode() ? false : undefined
       })
 
       if (!paths?.length) {
@@ -347,7 +349,7 @@ export function useComposerActions({ activeSessionId, currentCwd, requestGateway
       attachToMain(baseAttachment)
 
       try {
-        const previewUrl = await window.hermesDesktop?.readFileDataUrl(filePath)
+        const previewUrl = await readDesktopFileDataUrl(filePath)
 
         if (previewUrl) {
           addComposerAttachment({ ...baseAttachment, previewUrl })
@@ -395,7 +397,7 @@ export function useComposerActions({ activeSessionId, currentCwd, requestGateway
   )
 
   const pickImages = useCallback(async () => {
-    const paths = await window.hermesDesktop?.selectPaths({
+    const paths = await selectDesktopPaths({
       title: copy.attachImages,
       defaultPath: currentCwd || undefined,
       filters: [

apps/desktop/src/lib/desktop-fs.test.ts

@@ -4,6 +4,7 @@ import { $connection } from '@/store/session'
 
 import {
   desktopDefaultCwd,
+  desktopFileDiff,
   desktopGitRoot,
   readDesktopDir,
   readDesktopFileDataUrl,
@@ -39,6 +40,10 @@ const api = vi.fn(async ({ path }: { path: string }) => {
     return { cwd: '/backend/project', branch: 'main' }
   }
 
+  if (path.startsWith('/api/git/file-diff?')) {
+    return { diff: 'remote diff' }
+  }
+
   throw new Error(`unexpected path ${path}`)
 })
 
@@ -107,6 +112,13 @@ describe('desktop filesystem facade', () => {
     expect(gitRoot).not.toHaveBeenCalled()
   })
 
+  it('routes file diffs through backend git in remote mode', async () => {
+    $connection.set({ mode: 'remote' } as never)
+
+    await expect(desktopFileDiff('/repo', 'src/a b.ts')).resolves.toBe('remote diff')
+    expect(api).toHaveBeenCalledWith({ path: '/api/git/file-diff?path=%2Frepo&file=src%2Fa%20b.ts' })
+  })
+
   it('uses the registered in-app directory picker in remote mode', async () => {
     const remoteSelect = vi.fn(async () => ['/remote/project'])
     $connection.set({ mode: 'remote' } as never)

tests/hermes_cli/test_web_server_git.py

@@ -106,6 +106,14 @@ def test_stage_commit_roundtrip_clears_changes(client, repo):
     assert after["untracked"] == 1
 
 
+def test_commit_with_nothing_staged_commits_all_changes(client, repo):
+    assert client.post(
+        "/api/git/review/commit", json={"path": str(repo), "message": "commit all", "push": False}
+    ).json() == {"ok": True}
+
+    assert client.get("/api/git/status", params={"path": str(repo)}).json()["changed"] == 0
+
+
 def test_worktrees_and_branch_lifecycle(client, repo):
     worktrees = client.get("/api/git/worktrees", params={"path": str(repo)}).json()["worktrees"]
     assert any(tree["isMain"] and tree["path"] == str(repo) for tree in worktrees)
@@ -125,6 +133,26 @@ def test_worktrees_and_branch_lifecycle(client, repo):
     assert removed["removed"]
 
 
+def test_worktree_add_initializes_plain_folder(client, tmp_path):
+    folder = tmp_path / "plain-project"
+    folder.mkdir()
+    (folder / "notes.txt").write_text("not committed\n")
+
+    added = client.post(
+        "/api/git/worktree/add", json={"path": str(folder), "branch": "feature/plain"}
+    ).json()
+
+    assert added["branch"] == "feature/plain"
+    assert Path(added["path"]).is_dir()
+    assert (folder / ".git").exists()
+    _git(folder, "rev-parse", "--verify", "HEAD")
+
+    status = client.get("/api/git/status", params={"path": str(folder)}).json()
+    assert status["branch"] == "main"
+    # Existing files are not silently committed by repo initialization.
+    assert any(file["path"] == "notes.txt" and file["untracked"] for file in status["files"])
+
+
 def test_commit_context_includes_diff_and_untracked(client, repo):
     body = client.get("/api/git/review/commit-context", params={"path": str(repo)}).json()