Support removing workspace folders from a running session

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Add `eca-chat-remove-workspace-root` command and `[-]` mode-line button to remove a workspace folder from a running session. Both 'add' and 'remove' is in the transient menu (`W a` / `W r`).
 - Add `eca-chat-mode-line-format` for customizable chat mode line layout. #184
 - Fix top-level `(require 'tab-line)` causing side effects when `eca-chat-tab-line` is nil. #195
 - Add support for `chat/opened` server notification, enabling the `/fork` command to open forked chats as new tabs.

eca-chat.el

@@ -167,7 +167,7 @@ Must be a valid model supported by server, check `eca-chat-select-model`."
   :group 'eca)
 
 (defcustom eca-chat-mode-line-format
-  '(:workspace-folders :add-workspace-button :spacer :init-progress "  " :bg-jobs " " :elapsed-time "   " :usage " " :trust)
+  '(:workspace-folders :add-workspace-button :remove-workspace-button :spacer :init-progress "  " :bg-jobs " " :elapsed-time "   " :usage " " :trust)
   "Format for the ECA chat mode line.
 
 When set to a list, each element is a module keyword or a
@@ -177,6 +177,7 @@ to separate left-aligned and right-aligned content.
 Available modules:
   `:workspace-folders' - project root paths
   `:add-workspace-button' - clickable [+] button
+  `:remove-workspace-button' - clickable [-] button
   `:title' - chat title
   `:elapsed-time' - turn duration timer
   `:usage' - token/cost info (see `eca-chat-usage-string-format')
@@ -196,6 +197,7 @@ This gives full control for powerline or doom-modeline users."
             (string :tag "Literal string")
             (const :tag "Workspace folders" :workspace-folders)
             (const :tag "Add workspace button" :add-workspace-button)
+            (const :tag "Remove workspace button" :remove-workspace-button)
             (const :tag "Background jobs" :bg-jobs)
             (const :tag "Chat title" :title)
             (const :tag "Elapsed time" :elapsed-time)
@@ -1762,13 +1764,38 @@ E is the mouse event."
       (eca--session-add-workspace-folder session folder)
       (force-mode-line-update))))
 
+(defun eca-chat-remove-workspace-root ()
+  "Prompt for a workspace folder to remove from the current session.
+Refuses when only one folder remains.  In `merged' worktree mode, a
+removed folder sharing its git-common-dir with another session folder
+may be auto-re-added on the next buffer visit."
+  (interactive)
+  (when-let ((session (eca-session)))
+    (let ((folders (eca--session-workspace-folders session)))
+      (cond
+       ((null folders)
+        (user-error "No workspace folders to remove"))
+       ((<= (length folders) 1)
+        (user-error "Cannot remove the last workspace folder"))
+       (t
+        (let ((folder (completing-read "Remove workspace: " folders nil t)))
+          (eca--session-remove-workspace-folder session folder)
+          (force-mode-line-update)))))))
+
 (defvar eca-chat--add-workspace-map
   (let ((map (make-sparse-keymap)))
     (define-key map [mode-line mouse-1]
                 #'eca-chat-add-workspace-root)
     map)
   "Keymap for the modeline [+] workspace button.")
 
+(defvar eca-chat--remove-workspace-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map [mode-line mouse-1]
+                #'eca-chat-remove-workspace-root)
+    map)
+  "Keymap for the modeline [-] workspace button.")
+
 (defvar eca-chat--trust-toggle-map
   (let ((map (make-sparse-keymap)))
     (define-key map [mode-line mouse-1]
@@ -1813,6 +1840,12 @@ are in progress."
                  'mouse-face 'highlight
                  'help-echo "Add workspace folder"
                  'local-map eca-chat--add-workspace-map))
+    (:remove-workspace-button
+     (propertize " [-]"
+                 'face 'shadow
+                 'mouse-face 'highlight
+                 'help-echo "Remove workspace folder"
+                 'local-map eca-chat--remove-workspace-map))
     (:bg-jobs
      (when-let* ((jobs (eca--session-jobs session))
                  (running (seq-count (lambda (j) (string= "running" (plist-get j :status))) jobs)))

eca-util.el

@@ -192,6 +192,34 @@ workspace folders. Returns nil otherwise."
                            :removed [])))
       (eca-info "Added workspace folder: %s" folder))))
 
+(defun eca--session-remove-workspace-folder (session folder)
+  "Remove FOLDER from SESSION's workspace-folders and notify the server.
+Refuses to remove the last remaining folder, since the Emacs client
+resolves buffers to sessions by matching against workspace-folders and
+an empty list would make the session unreachable.  In `merged' worktree
+mode, a removed folder whose git-common-dir still matches another
+folder in the session can be auto-re-added by `eca-session' the next
+time a buffer under it is visited."
+  (let* ((folder (expand-file-name folder))
+         (folders (eca--session-workspace-folders session)))
+    (cond
+     ((not (--first (string= it folder) folders))
+      (eca-warn "Workspace folder not found: %s" folder))
+     ((<= (length folders) 1)
+      (user-error "Cannot remove the last workspace folder"))
+     (t
+      (setf (eca--session-workspace-folders session)
+            (cl-remove-if (lambda (it) (string= it folder)) folders))
+      (eca-api-notify
+       session
+       :method "workspace/didChangeWorkspaceFolders"
+       :params (list :event
+                     (list :added []
+                           :removed (vector
+                                     (list :uri (eca--path-to-uri folder)
+                                           :name (file-name-nondirectory (directory-file-name folder)))))))
+      (eca-info "Removed workspace folder: %s" folder)))))
+
 (defun eca-session ()
   "Return the session related to root of current buffer otherwise nil."
   (or (eca-get eca--sessions eca--session-id-cache)
@@ -327,7 +355,11 @@ Inheirits BASE-MAP."
 
      ["Server"
       ("S r" "Restart" eca-restart)
-      ("S s" "Stop" eca-stop)]]))
+      ("S s" "Stop" eca-stop)]
+
+     ["Workspace"
+      ("W a" "Add folder" eca-chat-add-workspace-root)
+      ("W r" "Remove folder" eca-chat-remove-workspace-root)]]))
 
 (defun eca-transient-menu ()
   "Open the ECA transient menu.