Fix tp-text to update when text properties differ even if text is same

- Added `tp--equal-including-string-properties` helper function that uses
  `equal-including-properties` for strings to properly detect changes in
  text properties when the text content is the same
- Updated `tp--reactive-variable-watcher` to use this new comparison function
- Updated `tp--replace-reactive-text-in-buffer` to use `tp-add` when text
  content is the same but properties may differ
- Added test `tp-test-tp-text-same-text-different-properties` to verify
  the fix

Co-authored-by: Kinneyzhang <38454496+Kinneyzhang@users.noreply.github.com>

tp-tests.el

@@ -3038,6 +3038,34 @@ the inserted text should be that string, not the source text."
       (ignore-errors (makunbound 'tp-test-name-part2))
       (ignore-errors (makunbound 'tp-test-full-text)))))
 
+(ert-deftest tp-test-tp-text-same-text-different-properties ()
+  "Test tp-text updates when text is same but properties differ.
+When the reactive variable changes to a propertized string with the same
+text content but different properties, the properties should be updated."
+  (tp-test-with-temp-buffer
+    (defvar tp-test-same-text nil "Test variable for same text different props.")
+    (setq tp-test-same-text "emacs")
+    (unwind-protect
+        (progn
+          (define-tp test-same-text-layer ()
+            :props '(face (:foreground "green") tp-text $tp-test-same-text))
+          ;; Apply layer to text
+          (insert "placeholder text here")
+          (tp-set 1 17 'test-same-text-layer)
+          ;; Initial text should be "emacs" with foreground green
+          (should (equal (buffer-substring-no-properties 1 6) "emacs"))
+          (should (equal (plist-get (tp-at 1 'face) :foreground) "green"))
+          ;; Change the reactive variable to same text but different properties
+          (setq tp-test-same-text (propertize "emacs" 'face 'bold))
+          ;; Text should still be "emacs"
+          (should (equal (buffer-substring-no-properties 1 6) "emacs"))
+          ;; Face should now include bold from the propertized string
+          (let ((face-val (tp-at 1 'face)))
+            (should (or (eq face-val 'bold)
+                        (and (listp face-val) (memq 'bold face-val))))))
+      ;; Cleanup
+      (makunbound 'tp-test-same-text))))
+
 ;;; ============================================================
 ;;; tp-text with Embedded Text Properties Tests
 ;;; ============================================================

tp.el

@@ -258,6 +258,15 @@ Scans the entire string, not just position 0."
   (and (stringp str)
        (not (null (object-intervals str)))))
 
+(defun tp--equal-including-string-properties (a b)
+  "Compare A and B for equality, considering string text properties.
+If either A or B is a string, uses `equal-including-properties' to ensure
+text properties are considered in the comparison.
+Otherwise, uses standard `equal'."
+  (if (or (stringp a) (stringp b))
+      (equal-including-properties a b)
+    (equal a b)))
+
 (defun tp--parse-face-list (face-list)
   "Parse a mixed face list into symbols and a plist.
 FACE-LIST can be a mix of:
@@ -621,8 +630,11 @@ Only 'set' operations trigger updates because:
 - 'defvaralias': Aliasing, the actual value change will trigger a separate 'set'
 
 When `tp--batch-update-active' is non-nil, buffer updates are deferred until
-the batch completes. Layer definitions are still updated immediately."
-  (when (and (not (equal (symbol-value symbol) newval))
+the batch completes. Layer definitions are still updated immediately.
+
+Uses `tp--equal-including-string-properties' for comparison to properly detect
+changes in text properties when the text content is the same."
+  (when (and (not (tp--equal-including-string-properties (symbol-value symbol) newval))
              (eq operation 'set))
     (tp-debug-log "Variable %s changed: %S -> %S (where: %s)"
                   symbol (symbol-value symbol) newval
@@ -998,9 +1010,11 @@ Text properties embedded in NEW-TEXT are merged with PROPS."
       (let* ((m-start (prop-match-beginning match))
              (m-end (prop-match-end match))
              (old-text (buffer-substring-no-properties m-start m-end)))
-        ;; Only replace if text content is different
-        (unless (equal old-text (substring-no-properties new-text))
-          ;; Delete old text and insert new (without properties)
+        (if (equal old-text (substring-no-properties new-text))
+            ;; Text content is the same, but properties may differ
+            ;; Use tp-add to update properties (merges embedded props from new-text)
+            (tp-add m-start m-end merged-props)
+          ;; Text content is different - delete old text and insert new
           (delete-region m-start m-end)
           (goto-char m-start)
           (insert (substring-no-properties new-text))