From 9a65f85fe86348c543062c8ff985f70d489a46ec Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 1 Jan 2026 17:09:37 +0000
Subject: [PATCH] Fix property merging when combining custom layers with
 built-in properties

Co-authored-by: Kinneyzhang <38454496+Kinneyzhang@users.noreply.github.com>
---
 tp.el | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/tp.el b/tp.el
index 9e9fa5c..c3e6364 100644
--- a/tp.el
+++ b/tp.el
@@ -1066,8 +1066,8 @@ Supports multiple calling conventions:
       (setq props (car props)))
     ;; Merge duplicate keys in the plist (for single-call property setting)
     ;; This must happen before tp--resolve-props to properly handle face merging
-    ;; Use (cddr props) for O(1) check instead of (> (length props) 2)
-    (when (and (listp props) (cddr props))
+    ;; Use (cdddr props) for O(1) check - need at least 4 elements (2 key-value pairs) for possible duplicates
+    (when (and (listp props) (cdddr props))
       (setq props (tp--merge-duplicate-keys props)))
     ;; Resolve props: handles layer/group names and anonymous reactive plists
     (when props
@@ -2868,8 +2868,8 @@ Returns the expanded plist."
           (setq result (append result (list key val)))))
         (setq remaining (cddr remaining))))
     ;; Merge duplicate keys in the expanded result
-    ;; Use (cddr result) for O(1) check instead of (> (length result) 2)
-    (if (cddr result)
+    ;; Use (cdddr result) for O(1) check - need at least 4 elements (2 key-value pairs) for possible duplicates
+    (if (cdddr result)
         (tp--merge-duplicate-keys result)
       result)))
 
@@ -2938,8 +2938,13 @@ For group names, includes `tp-layers' property with the full layer stack."
           ;; Recursively resolve extra properties (they may also contain layer names)
           (let ((expanded-props
                  (if (and layer-props extra-props)
-                     (let ((resolved-extra (tp--expand-layer-in-plist extra-props)))
-                       (append layer-props resolved-extra))
+                     (let* ((resolved-extra (tp--expand-layer-in-plist extra-props))
+                            (combined (append layer-props resolved-extra)))
+                       ;; Merge duplicate keys after combining layer props with extra props
+                       ;; Need at least 4 elements (2 key-value pairs) for possible duplicates
+                       (if (cdddr combined)
+                           (tp--merge-duplicate-keys combined)
+                         combined))
                    layer-props)))
             ;; After expansion, check for reactive symbols in the merged props
             ;; (original props may contain $vars that need reactive tracking)