feat(completion): right-align custom category annotations

marginalia-align has been right for months, but annotations from the custom completion categories (radio stations, music files, and everything built through the system-lib table helpers) never went through marginalia. They rendered unaligned. A registration helper adds a builtin registry entry per category at table construction, which routes the table's own annotation function through marginalia's aligned field. The radio table converts from an affixation function with hand-rolled padding to a plain annotation, since marginalia now owns the alignment. Self-maintaining: any future custom category built through the helpers registers itself.

2 files changed, 33 insertions, 23 deletions

diff --git a/modules/music-config.el b/modules/music-config.el
index e9095838..a70516e2 100644
--- a/modules/music-config.el
+++ b/modules/music-config.el
@@ -306,7 +306,9 @@ Directories are suffixed with /; files are plain. Hidden dirs/files skipped."
   "Completion table for CANDIDATES preserving order and case-insensitive match.
 Tags the `cj-music-file' category and annotates each candidate (a path relative
 to `cj/music-root', with a trailing slash for directories) with its size and
-modification date so marginalia can show them."
+modification date so marginalia can show them.  The category is registered
+with marginalia (builtin) so the annotations render right-aligned."
+  (cj/completion-ensure-marginalia-align 'cj-music-file)
   (let ((annotate (cj/completion-file-annotator
                    (lambda (c)
                      (expand-file-name
@@ -1790,32 +1792,22 @@ to one station.  Pure helper."
         (puthash disp t seen)
         (push (cons disp st) out)))))
 
-(defun cj/music-radio--affixate (cands candidates)
-  "Affixation triples for CANDS with annotations aligned to one column.
-CANDIDATES is the (DISPLAY . STATION) alist.  Station names vary in width,
-so each suffix pads out to the widest candidate plus a gutter; with the
-fixed-width fields in `cj/music-radio--format-candidate' the listing reads
-as aligned columns.  The \"[done]\" sentinel has no station and gets no
-annotation rather than a bogus zero row."
-  (let ((width (apply #'max 0 (mapcar #'string-width cands))))
-    (mapcar (lambda (c)
-              (let ((st (cdr (assoc c candidates))))
-                (list c ""
-                      (if st
-                          (concat (make-string (+ 3 (- width (string-width c))) ?\s)
-                                  (propertize (cj/music-radio--format-candidate st)
-                                              'face 'completions-annotations))
-                        ""))))
-            cands)))
-
 (defun cj/music-radio--completion-table (candidates)
-  "Completion table over CANDIDATES carrying the Variant-B marginalia affix."
+  "Completion table over CANDIDATES carrying the Variant-B annotation.
+Tagged `cj-radio-station' and registered with marginalia (builtin), so the
+codec/bitrate/country/votes/tags annotation renders right-aligned like the
+stock categories.  The \"[done]\" sentinel has no station and annotates as
+nil rather than a bogus zero row."
+  (cj/completion-ensure-marginalia-align 'cj-radio-station)
   (lambda (string pred action)
     (if (eq action 'metadata)
         `(metadata
           (category . cj-radio-station)
-          (affixation-function
-           . ,(lambda (cands) (cj/music-radio--affixate cands candidates))))
+          (annotation-function
+           . ,(lambda (c)
+                (when-let ((st (cdr (assoc c candidates))))
+                  (concat " " (propertize (cj/music-radio--format-candidate st)
+                                          'face 'completions-annotations))))))
       (complete-with-action action (mapcar #'car candidates) string pred))))
 
 (defun cj/music-radio--pick-loop (candidates)
diff --git a/modules/system-lib.el b/modules/system-lib.el
index f1049c02..54e20b74 100644
--- a/modules/system-lib.el
+++ b/modules/system-lib.el
@@ -164,6 +164,22 @@ contributes its own modes regardless of load order."
     (setq font-lock-global-modes
           (cj/--font-lock-global-modes-excluding font-lock-global-modes mode))))
 
+;; Declared special here for the compiler; marginalia owns the defvar.
+(defvar marginalia-annotator-registry)
+
+(defun cj/completion-ensure-marginalia-align (category)
+  "Register CATEGORY with marginalia as builtin-annotated, once.
+A custom completion category bypasses marginalia entirely, so the table's
+own annotation function renders unaligned even with `marginalia-align'
+set.  A builtin registry entry tells marginalia to use the table's
+annotation function inside its aligned field, so custom annotations line
+up like every stock category.  A category that already has an entry is
+left alone (someone chose its annotators deliberately).  Silent no-op
+when marginalia isn't loaded."
+  (when (and (boundp 'marginalia-annotator-registry)
+             (not (assq category marginalia-annotator-registry)))
+    (push (list category 'builtin 'none) marginalia-annotator-registry)))
+
 (defun cj/completion-table (category collection)
   "Return a completion table over COLLECTION tagged with completion CATEGORY.
 COLLECTION is anything `completing-read' accepts (list, alist, obarray, hash
@@ -180,7 +196,9 @@ the candidates match one; marginalia then annotates them with no further work."
   "Like `cj/completion-table' but also attach ANNOTATE as the annotation function.
 ANNOTATE is called with a candidate string and returns its annotation suffix, or
 nil.  Use this for a custom CATEGORY that marginalia has no built-in annotator
-for: marginalia falls back to the table's own annotation function."
+for; the category is registered with marginalia (builtin) so ANNOTATE's output
+renders right-aligned like stock annotations."
+  (cj/completion-ensure-marginalia-align category)
   (lambda (string predicate action)
     (if (eq action 'metadata)
         `(metadata (category . ,category)