fix: normalize header extension status rendering

pi-coding-agent-ui.el

@@ -1239,9 +1239,9 @@ Returns nil if CONTEXT-WINDOW is 0."
     (if (null context-tokens)
         (format " ?/%s" (pi-coding-agent--format-tokens-compact context-window))
       (let* ((pct (* (/ (float context-tokens) context-window) 100))
-             ;; Note: %% needed because % has special meaning in header-line-format
-             (pct-str (format " %.1f%%%%/%s" pct
-                              (pi-coding-agent--format-tokens-compact context-window))))
+             (pct-str (pi-coding-agent--header-escape-text
+                       (format " %.1f%%/%s" pct
+                               (pi-coding-agent--format-tokens-compact context-window)))))
         (propertize pct-str
                     'face (cond
                            ((> pct pi-coding-agent-context-error-threshold) 'error)
@@ -1269,13 +1269,17 @@ Returns nil if STATS is nil."
        (format " $%.2f" cost)
        (pi-coding-agent--header-format-context context-tokens context-window)))))
 
+(defun pi-coding-agent--header-escape-text (text)
+  "Escape TEXT for use in `header-line-format'."
+  (replace-regexp-in-string "%" "%%" text t t))
+
 (defun pi-coding-agent--header-format-extension-status (ext-status)
   "Format EXT-STATUS alist for header-line display.
 Returns extension statuses joined with \" · \", or empty string."
   (if (null ext-status)
       ""
     (mapconcat (lambda (pair)
-                 (propertize (cdr pair) 'face 'pi-coding-agent-retry-notice))
+                 (pi-coding-agent--header-escape-text (cdr pair)))
                ext-status
                " · ")))
 
@@ -1310,7 +1314,8 @@ Returns a leading-pipe group string or empty string
 when no extension info exists."
   (let* ((status-str (pi-coding-agent--header-format-extension-status ext-status))
          (working-str (if (and working-message (not (string-empty-p working-message)))
-                          (propertize working-message 'face 'shadow)
+                          (propertize (pi-coding-agent--header-escape-text working-message)
+                                      'face 'shadow)
                         ""))
          (parts nil))
     (unless (string-empty-p status-str)

test/pi-coding-agent-input-test.el

@@ -2214,6 +2214,17 @@ Pi handles command expansion on the server side."
       (should (string-match-p "My Session" header))
       (should (string-match-p "Git: synced · 📖 Skimming…" header)))))
 
+(ert-deftest pi-coding-agent-test-header-extension-group-escapes-percent-signs ()
+  "Extension header text escapes percent signs for header-line display."
+  (with-temp-buffer
+    (pi-coding-agent-chat-mode)
+    (setq pi-coding-agent--state '(:model (:name "gpt-5.4" :contextWindow 200000))
+          pi-coding-agent--extension-status '(("sub-status:usage" . "5h 4% · Week 3% · degraded"))
+          pi-coding-agent--working-message "refresh 50%")
+    (let ((header (substring-no-properties (pi-coding-agent--header-line-string))))
+      (should (string-match-p "5h 4%% · Week 3%% · degraded" header))
+      (should (string-match-p "refresh 50%%" header)))))
+
 (ert-deftest pi-coding-agent-test-header-session-name-in-context-group ()
   "Context group shows session name when set, collapses when nil."
   (with-temp-buffer

test/pi-coding-agent-render-test.el

@@ -1182,13 +1182,16 @@ since we don't display them locally. Let pi's message_start handle it."
     (should (null pi-coding-agent--working-message))))
 
 (ert-deftest pi-coding-agent-test-header-format-extension-status ()
-  "Extension status formatter returns inline status text without pipe."
+  "Extension status formatter returns inline neutral status text without pipe."
   ;; Empty status returns empty string
   (should (equal (pi-coding-agent--header-format-extension-status nil) ""))
   ;; Single status
-  (let ((result (pi-coding-agent--header-format-extension-status '(("ext1" . "Processing...")))))
+  (let* ((result (pi-coding-agent--header-format-extension-status '(("ext1" . "Processing..."))))
+         (pos (string-match "Processing" result)))
     (should-not (string-match-p "│" result))
-    (should (string-match-p "Processing" result)))
+    (should (string-match-p "Processing" result))
+    (should pos)
+    (should-not (get-text-property pos 'face result)))
   ;; Multiple statuses joined with separator
   (let ((result (pi-coding-agent--header-format-extension-status
                  '(("ext1" . "Status 1") ("ext2" . "Status 2")))))