feat(ai-vterm): surface surviving tmux sessions in the project picker

Each project's tmux session is now named `<cj/ai-vterm-tmux-session-prefix><basename>` (default `aiv-`), so `tmux ls` can be filtered to AI-vterm's own sessions. After an Emacs crash the C-F9 project picker reads `tmux list-sessions`, matches surviving sessions back to their directories, and sorts those to the top: `[detached]` when only the tmux session is alive, `[running]` when a vterm buffer exists. The rest follow alphabetically. With tmux missing or no server running, it falls back to a plain alphabetical list. The picker's collection is a completion table that pins display order so Vertico doesn't re-sort and undo the active-first grouping.

The prefix is a new `defcustom` rather than `claude-`, which collides with hand-rolled tmux sessions. Sessions named before this change use the bare basename and won't be matched afterward. One `tmux kill-server` clears any orphans.

1 files changed, 28 insertions, 16 deletions

diff --git a/tests/test-ai-vterm--tmux-session-name.el b/tests/test-ai-vterm--tmux-session-name.el
index 9d56040ed..44c20a8be 100644
--- a/tests/test-ai-vterm--tmux-session-name.el
+++ b/tests/test-ai-vterm--tmux-session-name.el
@@ -1,11 +1,12 @@
 ;;; test-ai-vterm--tmux-session-name.el --- Tests for cj/--ai-vterm-tmux-session-name -*- lexical-binding: t; -*-
 
 ;;; Commentary:
-;; The tmux session name is derived from the project's basename so that
-;; reopening Claude on the same project (e.g. after an Emacs crash)
-;; reattaches to the same tmux session rather than spawning a new one.
-;; Whitespace in the basename gets converted to hyphens so the name is
-;; safe to pass on a tmux command line.
+;; The tmux session name is `cj/ai-vterm-tmux-session-prefix' followed by
+;; the project's basename, so reopening Claude on the same project (e.g.
+;; after an Emacs crash) reattaches to the same tmux session rather than
+;; spawning a new one -- and the prefix lets `tmux ls' output be filtered
+;; down to AI-vterm's own sessions.  Whitespace in the basename becomes
+;; hyphens so the name is safe to pass on a tmux command line.
 
 ;;; Code:
 
@@ -15,29 +16,40 @@
 (require 'ai-vterm)
 
 (ert-deftest test-ai-vterm--tmux-session-name-normal-project ()
-  "Normal: a typical project path yields its basename."
-  (should (equal (cj/--ai-vterm-tmux-session-name "/home/cjennings/projects/foo")
-                 "foo")))
+  "Normal: basename gets the configured prefix."
+  (let ((cj/ai-vterm-tmux-session-prefix "aiv-"))
+    (should (equal (cj/--ai-vterm-tmux-session-name "/home/cjennings/projects/foo")
+                   "aiv-foo"))))
 
 (ert-deftest test-ai-vterm--tmux-session-name-trailing-slash ()
   "Boundary: trailing slash collapses before basename extraction."
-  (should (equal (cj/--ai-vterm-tmux-session-name "/home/cjennings/projects/foo/")
-                 "foo")))
+  (let ((cj/ai-vterm-tmux-session-prefix "aiv-"))
+    (should (equal (cj/--ai-vterm-tmux-session-name "/home/cjennings/projects/foo/")
+                   "aiv-foo"))))
 
 (ert-deftest test-ai-vterm--tmux-session-name-dot-prefix-dir ()
   "Boundary: dot-prefix dirs preserve the dot (tmux accepts dots)."
-  (should (equal (cj/--ai-vterm-tmux-session-name "/home/cjennings/.emacs.d")
-                 ".emacs.d")))
+  (let ((cj/ai-vterm-tmux-session-prefix "aiv-"))
+    (should (equal (cj/--ai-vterm-tmux-session-name "/home/cjennings/.emacs.d")
+                   "aiv-.emacs.d"))))
 
 (ert-deftest test-ai-vterm--tmux-session-name-space-becomes-hyphen ()
   "Boundary: a space in the basename is replaced with a hyphen."
-  (should (equal (cj/--ai-vterm-tmux-session-name "/tmp/my work")
-                 "my-work")))
+  (let ((cj/ai-vterm-tmux-session-prefix "aiv-"))
+    (should (equal (cj/--ai-vterm-tmux-session-name "/tmp/my work")
+                   "aiv-my-work"))))
 
 (ert-deftest test-ai-vterm--tmux-session-name-multiple-spaces-collapse ()
   "Boundary: a run of whitespace collapses to a single hyphen."
-  (should (equal (cj/--ai-vterm-tmux-session-name "/tmp/a   b\tc")
-                 "a-b-c")))
+  (let ((cj/ai-vterm-tmux-session-prefix "aiv-"))
+    (should (equal (cj/--ai-vterm-tmux-session-name "/tmp/a   b\tc")
+                   "aiv-a-b-c"))))
+
+(ert-deftest test-ai-vterm--tmux-session-name-honors-custom-prefix ()
+  "Normal: a non-default prefix is what gets prepended."
+  (let ((cj/ai-vterm-tmux-session-prefix "em-"))
+    (should (equal (cj/--ai-vterm-tmux-session-name "/home/cjennings/projects/foo")
+                   "em-foo"))))
 
 (provide 'test-ai-vterm--tmux-session-name)
 ;;; test-ai-vterm--tmux-session-name.el ends here