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, 51 insertions, 0 deletions

diff --git a/tests/test-ai-vterm--sort-candidates.el b/tests/test-ai-vterm--sort-candidates.el
new file mode 100644
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+++ b/tests/test-ai-vterm--sort-candidates.el
@@ -0,0 +1,51 @@
+;;; test-ai-vterm--sort-candidates.el --- Tests for cj/--ai-vterm-sort-candidates -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; The project picker lists candidates with a live tmux session first
+;; (so a Claude that survived an Emacs crash is easy to get back to),
+;; then everything else.  Within each group the order is alphabetical
+;; by abbreviated path.
+
+;;; Code:
+
+(require 'ert)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'ai-vterm)
+
+(ert-deftest test-ai-vterm--sort-candidates-active-first-then-alpha ()
+  "Normal: the one project with a live session leads; the rest go alpha."
+  (let ((cj/ai-vterm-tmux-session-prefix "aiv-"))
+    (should (equal (cj/--ai-vterm-sort-candidates
+                    '("/c/foo" "/c/bar" "/c/baz")
+                    '("aiv-bar"))
+                   '("/c/bar" "/c/baz" "/c/foo")))))
+
+(ert-deftest test-ai-vterm--sort-candidates-multiple-active-each-group-alpha ()
+  "Normal: both groups sort alphabetically internally."
+  (let ((cj/ai-vterm-tmux-session-prefix "aiv-"))
+    (should (equal (cj/--ai-vterm-sort-candidates
+                    '("/c/foo" "/c/bar" "/c/baz")
+                    '("aiv-foo" "aiv-bar"))
+                   '("/c/bar" "/c/foo" "/c/baz")))))
+
+(ert-deftest test-ai-vterm--sort-candidates-no-sessions-is-plain-alpha ()
+  "Boundary: nil session set -> a plain alphabetical list."
+  (let ((cj/ai-vterm-tmux-session-prefix "aiv-"))
+    (should (equal (cj/--ai-vterm-sort-candidates
+                    '("/c/foo" "/c/bar") nil)
+                   '("/c/bar" "/c/foo")))))
+
+(ert-deftest test-ai-vterm--sort-candidates-empty-dirs-yields-nil ()
+  "Boundary: no candidates -> nil."
+  (should (null (cj/--ai-vterm-sort-candidates nil '("aiv-foo")))))
+
+(ert-deftest test-ai-vterm--session-active-p-matches-by-derived-name ()
+  "Normal: a dir is active when its derived session name is in the set."
+  (let ((cj/ai-vterm-tmux-session-prefix "aiv-"))
+    (should (cj/--ai-vterm-session-active-p "/c/foo" '("aiv-bar" "aiv-foo")))
+    (should-not (cj/--ai-vterm-session-active-p "/c/qux" '("aiv-bar" "aiv-foo")))
+    (should-not (cj/--ai-vterm-session-active-p "/c/foo" nil))))
+
+(provide 'test-ai-vterm--sort-candidates)
+;;; test-ai-vterm--sort-candidates.el ends here