Rewrite nrepl-log--pp-listlike as a single pass

The old implementation copy-sequence'd the cdr, seq-partition'd into
pairs, sorted alphabetically, seq-map'd for name lengths, seq-max'd,
seq-filter + seq-remove'd to split off special keys, seq-concatenate'd
twice, apply'd seq-concatenate to flatten back into a plist, then
cl-loop'd to emit -- roughly six list-sized allocations plus an
O(n log n) sort per logged message, half of it just to assemble a
plist that immediately got destructured again.

Replace with one pass: bucket special keys into a fixed-position
vector (so they emit in canonical id/op/session/time-stamp order
without sorting), collect the rest in insertion order, and track the
widest key inline for column alignment.  No more sort, no more
copy-sequence, allocations down to a single small vector plus the
others list.

Behavior change: non-special keys now print in the order they appeared
in the dict instead of alphabetically.  The order reflects how the
peer constructed the message, which is more useful for protocol
debugging than alphabetic by accident.

Author: bbatsov

lisp/nrepl-client.el

@@ -1396,6 +1396,9 @@ If ID is nil, return nil."
       (mod (length nrepl-message-colors))
       (nth nrepl-message-colors))))
 
+(defconst nrepl-log--special-keys '("id" "op" "session" "time-stamp")
+  "Keys that are displayed first, in this order, in `nrepl-log--pp-listlike'.")
+
 (defun nrepl-log--pp-listlike (object &optional foreground button)
   "Pretty print nREPL list like OBJECT.
 FOREGROUND and BUTTON are as in `nrepl-log-pp-object'."
@@ -1407,28 +1410,32 @@ FOREGROUND and BUTTON are as in `nrepl-log-pp-object'."
       (insert (color head))
       (if (null (cdr object))
           (insert ")\n")
+        ;; Walk the plist once: bucket pairs whose key is in
+        ;; `nrepl-log--special-keys' into a fixed-position vector so they
+        ;; emit in canonical order, collect the rest in insertion order,
+        ;; and track the widest key for column alignment.  Replaces a
+        ;; pipeline that copy-sequence'd, partitioned, sorted, mapped,
+        ;; filtered, removed, and concatenated the plist for every message.
         (let* ((indent (+ 2 (- (current-column) (length head))))
-               (sorted-pairs (sort (seq-partition (copy-sequence (cdr object)) 2)
-                                   (lambda (a b)
-                                     (string< (car a) (car b)))))
-               (name-lengths (seq-map (lambda (pair) (length (car pair))) sorted-pairs))
-               (longest-name (seq-max name-lengths))
-               ;; Special entries are displayed first
-               (specialq (lambda (pair) (member (car pair) '("id" "op" "session" "time-stamp"))))
-               (special-pairs (seq-filter specialq sorted-pairs))
-               (not-special-pairs (seq-remove specialq sorted-pairs))
-               (all-pairs (seq-concatenate 'list special-pairs not-special-pairs))
-               (sorted-object (apply #'seq-concatenate 'list all-pairs)))
+               (specials (make-vector (length nrepl-log--special-keys) nil))
+               (others nil)
+               (longest-name 0))
+          (cl-loop for (k v) on (cdr object) by #'cddr
+                   do (setq longest-name (max longest-name (length k)))
+                   do (let ((idx (cl-position k nrepl-log--special-keys :test #'equal)))
+                        (if idx
+                            (aset specials idx (cons k v))
+                          (push (cons k v) others))))
           (insert "\n")
-          (cl-loop for l on sorted-object by #'cddr
-                   do (let ((indent-str (make-string indent ?\s))
-                            (name-str (propertize (car l) 'face
-                                                  ;; Only highlight top-level keys.
-                                                  (unless (eq (car object) 'dict)
-                                                    'font-lock-keyword-face)))
-                            (spaces-str (make-string (- longest-name (length (car l))) ?\s)))
-                        (insert (format "%s%s%s " indent-str name-str spaces-str))
-                        (nrepl-log-pp-object (cadr l) nil button)))
+          (let ((indent-str (make-string indent ?\s))
+                ;; Only highlight top-level keys.
+                (face (unless (eq (car object) 'dict) 'font-lock-keyword-face)))
+            (dolist (pair (nconc (delq nil (append specials nil)) (nreverse others)))
+              (let* ((k (car pair))
+                     (v (cdr pair))
+                     (spaces-str (make-string (- longest-name (length k)) ?\s)))
+                (insert indent-str (propertize k 'face face) spaces-str " ")
+                (nrepl-log-pp-object v nil button))))
           (when (eq (car object) 'dict)
             (delete-char -1))
           (insert (color ")\n")))))))