feat(music): always dock the playlist at the bottom

The F10 playlist docked as a right-side column when the frame was wide enough, splitting the frame three ways. That's annoying and often unexpected, so the frame's shape no longer decides where the playlist goes.

I deleted the chooser (cj/--music-playlist-side) and the right-dock width knobs rather than leaving them wired to nothing, and a test asserts they're gone. cj/preferred-dock-direction stays, since ai-term and eat still dock by frame shape.

The old side-chooser test is replaced by one that stubs cj/side-window-display and asserts what the toggle asks for, so it runs headless.

3 files changed, 87 insertions, 90 deletions

diff --git a/modules/music-config.el b/modules/music-config.el
index 7e3b9d0f..3559930b 100644
--- a/modules/music-config.el
+++ b/modules/music-config.el
@@ -30,7 +30,6 @@
 (require 'subr-x)
 (require 'user-constants)
 (require 'keybindings)  ;; provides cj/custom-keymap
-(require 'cj-window-geometry-lib) ;; cj/preferred-dock-direction (F10 dock side)
 (require 'cj-window-toggle-lib)  ;; side-window size memory (F10 toggle)
 (require 'system-lib)            ;; cj/confirm-strong (overwrite confirms)
 
@@ -778,40 +777,22 @@ Intended for use on `emms-player-finished-hook'."
 
 (defvar cj/music-playlist-window-height 0.3
   "Default fraction of frame height for the F10 music playlist side window.
-Used when the playlist docks at the bottom and hasn't been resized and
-toggled off this session; after that, the toggled-off height is remembered
-in `cj/--music-playlist-height'.")
-
-(defvar cj/music-playlist-window-width 0.4
-  "Default fraction of frame width for the F10 music playlist side window.
-Used when the playlist docks as a right-side column (see
-`cj/--music-playlist-side') and hasn't been resized this session; after
-that the toggled-off width is remembered in `cj/--music-playlist-width'.")
+Used when the playlist hasn't been resized and toggled off this session;
+after that, the toggled-off height is remembered in
+`cj/--music-playlist-height'.")
 
 (defvar cj/--music-playlist-height nil
-  "Last height fraction the playlist was toggled off at while docked bottom.
+  "Last height fraction the playlist was toggled off at.
 nil means fall back to `cj/music-playlist-window-height'.  In-memory only --
 resets each Emacs session.")
 
-(defvar cj/--music-playlist-width nil
-  "Last width fraction the playlist was toggled off at while docked right.
-nil means fall back to `cj/music-playlist-window-width'.  In-memory only --
-resets each Emacs session.")
-
-(defun cj/--music-playlist-side ()
-  "Return the side the F10 playlist should dock on: `right' or `bottom'.
-Docks as a right-side column only when a side-by-side split would leave
-both panes at least `cj/window-dock-min-columns' wide (the playlist's
-share is `cj/music-playlist-window-width'); otherwise docks at the bottom.
-See `cj/preferred-dock-direction'."
-  (if (eq (cj/preferred-dock-direction (frame-width)
-                                       cj/music-playlist-window-width)
-          'right)
-      'right
-    'bottom))
-
 (defun cj/music-playlist-toggle ()
   "Toggle the EMMS playlist buffer in a bottom side window.
+The playlist always docks at the bottom, whatever the frame's shape.  It
+used to dock as a right-side column on a wide frame (via
+`cj/preferred-dock-direction'), which split a wide frame three ways --
+unexpected often enough that Craig retired the rule (2026-07-09).
+
 The window opens at `cj/music-playlist-window-height'; if it has been
 resized and toggled off this session, it reopens at that remembered height."
   (interactive)
@@ -820,28 +801,15 @@ resized and toggled off this session, it reopens at that remembered height."
          (win (and buffer (get-buffer-window buffer))))
     (if win
         (progn
-          ;; Capture the resized size into the var matching the window's
-          ;; actual side, so width and height memories stay independent.
-          ;; Guard the parameter lookup: a dead or non-window WIN (the
-          ;; capture helpers tolerate one) must not error here.
-          (let ((side (if (window-live-p win)
-                          (or (window-parameter win 'window-side) 'bottom)
-                        'bottom)))
-            (if (memq side '(left right))
-                (cj/side-window-capture-size win side 'cj/--music-playlist-width)
-              (cj/side-window-capture-size win 'bottom 'cj/--music-playlist-height)))
+          (cj/side-window-capture-size win 'bottom 'cj/--music-playlist-height)
           (delete-window win)
           (message "Playlist window closed"))
       (progn
         (cj/emms--setup)
         (setq buffer (cj/music--ensure-playlist-buffer))
-        (let* ((side (cj/--music-playlist-side))
-               (right (eq side 'right)))
-          (setq win (cj/side-window-display
-                     buffer side
-                     (if right 'cj/--music-playlist-width 'cj/--music-playlist-height)
-                     (if right cj/music-playlist-window-width
-                       cj/music-playlist-window-height))))
+        (setq win (cj/side-window-display
+                   buffer 'bottom 'cj/--music-playlist-height
+                   cj/music-playlist-window-height))
         (select-window win)
         (with-current-buffer buffer
           (if (and (fboundp 'emms-playlist-current-selected-track)
diff --git a/tests/test-music-config--playlist-dock.el b/tests/test-music-config--playlist-dock.el
new file mode 100644
index 00000000..69d24cc3
--- /dev/null
+++ b/tests/test-music-config--playlist-dock.el
@@ -0,0 +1,74 @@
+;;; test-music-config--playlist-dock.el --- Tests for the F10 playlist dock -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; The F10 playlist always docks at the bottom, whatever the frame's shape.
+;; It used to pick `right' on a wide frame via `cj/preferred-dock-direction',
+;; which produced an unwanted three-way split on a wide terminal.
+;;
+;; `cj/side-window-display' is the window-system boundary here, so it is the
+;; thing stubbed (an ordinary defun -- safe to `cl-letf', unlike the frame-*
+;; subrs).  Stubbing it lets these tests assert what the toggle *asks for*
+;; without needing a live frame under `--batch'.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'music-config)
+
+(defmacro test-music-dock--with-captured-side (captured &rest body)
+  "Run BODY with the playlist display path stubbed, recording its args in CAPTURED.
+CAPTURED is set to a plist of :side, :size-var and :default-size."
+  (declare (indent 1))
+  `(let ((buffer (generate-new-buffer " *test-playlist*")))
+     (unwind-protect
+         (cl-letf (((symbol-function 'cj/emms--setup) (lambda (&rest _) nil))
+                   ((symbol-function 'cj/music--ensure-playlist-buffer)
+                    (lambda (&rest _) buffer))
+                   ((symbol-function 'emms-playlist-mode-center-current)
+                    (lambda (&rest _) nil))
+                   ((symbol-function 'cj/side-window-display)
+                    (lambda (_buf side size-var default-size)
+                      (setq ,captured (list :side side :size-var size-var
+                                            :default-size default-size))
+                      (selected-window))))
+           ,@body)
+       (kill-buffer buffer))))
+
+(ert-deftest test-music-config-playlist-toggle-docks-bottom-on-wide-frame ()
+  "Normal: a wide frame still docks the playlist at the bottom.
+A wide frame used to dock right, splitting the frame three ways."
+  (let (captured)
+    (test-music-dock--with-captured-side captured
+      (cl-letf (((symbol-function 'frame-width) (lambda (&rest _) 400)))
+        (cj/music-playlist-toggle)))
+    (should (eq 'bottom (plist-get captured :side)))))
+
+(ert-deftest test-music-config-playlist-toggle-docks-bottom-on-narrow-frame ()
+  "Boundary: a narrow frame docks at the bottom, as it always did."
+  (let (captured)
+    (test-music-dock--with-captured-side captured
+      (cl-letf (((symbol-function 'frame-width) (lambda (&rest _) 40)))
+        (cj/music-playlist-toggle)))
+    (should (eq 'bottom (plist-get captured :side)))))
+
+(ert-deftest test-music-config-playlist-toggle-uses-height-memory ()
+  "Normal: the bottom dock carries the height fraction and its memory var."
+  (let (captured)
+    (test-music-dock--with-captured-side captured
+      (cj/music-playlist-toggle))
+    (should (eq 'cj/--music-playlist-height (plist-get captured :size-var)))
+    (should (= cj/music-playlist-window-height (plist-get captured :default-size)))))
+
+(ert-deftest test-music-config-playlist-dock-has-no-width-knobs ()
+  "Error: the right-dock width variables are gone, not merely unused.
+A stale `cj/music-playlist-window-width' would read as a live knob that
+silently does nothing."
+  (should-not (boundp 'cj/music-playlist-window-width))
+  (should-not (boundp 'cj/--music-playlist-width))
+  (should-not (fboundp 'cj/--music-playlist-side)))
+
+(provide 'test-music-config--playlist-dock)
+;;; test-music-config--playlist-dock.el ends here
diff --git a/tests/test-music-config--playlist-side.el b/tests/test-music-config--playlist-side.el
deleted file mode 100644
index f4969469..00000000
--- a/tests/test-music-config--playlist-side.el
+++ /dev/null
@@ -1,45 +0,0 @@
-;;; test-music-config--playlist-side.el --- Tests for the F10 dock-side helper -*- lexical-binding: t; -*-
-
-;;; Commentary:
-;; `cj/--music-playlist-side' maps the shared dock rule's verdict to a
-;; `display-buffer-in-side-window' side: `right' stays `right', anything
-;; else becomes `bottom'.  The decision itself lives in
-;; `cj/preferred-dock-direction' (tested in test-cj-window-geometry-lib.el);
-;; here we stub it (an ordinary defun -- safe to `cl-letf', unlike the
-;; frame-* subrs) to prove the mapping and that the width fraction is
-;; passed through.
-
-;;; Code:
-
-(require 'ert)
-(require 'cl-lib)
-
-(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
-(require 'music-config)
-
-(ert-deftest test-music-config--playlist-side-right-verdict-is-right ()
-  "Normal: a `right' verdict from the dock rule docks the playlist right."
-  (cl-letf (((symbol-function 'cj/preferred-dock-direction)
-             (lambda (&rest _) 'right)))
-    (should (eq (cj/--music-playlist-side) 'right))))
-
-(ert-deftest test-music-config--playlist-side-below-verdict-is-bottom ()
-  "Normal: a `below' verdict maps to the `bottom' side window."
-  (cl-letf (((symbol-function 'cj/preferred-dock-direction)
-             (lambda (&rest _) 'below)))
-    (should (eq (cj/--music-playlist-side) 'bottom))))
-
-(ert-deftest test-music-config--playlist-side-passes-width-fraction ()
-  "Normal: the playlist's width fraction reaches the dock rule."
-  (let ((cj/music-playlist-window-width 0.4)
-        captured)
-    (cl-letf (((symbol-function 'cj/preferred-dock-direction)
-               (lambda (cols frac &rest _)
-                 (setq captured (list cols frac))
-                 'below)))
-      (cj/--music-playlist-side)
-      (should (= (nth 1 captured) 0.4))
-      (should (integerp (nth 0 captured))))))
-
-(provide 'test-music-config--playlist-side)
-;;; test-music-config--playlist-side.el ends here