fix(eww): inject the User-Agent reliably under byte-compilation

eww-config.el is lexical-binding and the User-Agent advice let-binds url.el's url-request-extra-headers, but the file never declared it special. The byte-compiler then bound it lexically, so the injected header never reached url-retrieve and the desktop User-Agent silently dropped in compiled production (eww kept working, just with the default UA). A top-level (defvar url-request-extra-headers) makes the compiler treat it as dynamic so the binding propagates. The advice tests, which exercise the compiled path, now pass.

1 files changed, 7 insertions, 0 deletions

diff --git a/modules/eww-config.el b/modules/eww-config.el
index a5271f6bc..ff7ddc211 100644
--- a/modules/eww-config.el
+++ b/modules/eww-config.el
@@ -44,6 +44,13 @@
   :type 'string
   :group 'my-eww-user-agent)
 
+;; This file is lexical-binding, so `let'-binding url.el's special var below
+;; needs it declared special at compile time.  Without this the byte-compiled
+;; advice binds `url-request-extra-headers' lexically and the injected
+;; User-Agent never reaches `url-retrieve' (it reads the dynamic value) -- the
+;; UA injection silently no-ops in compiled production, and the test sees nil.
+(defvar url-request-extra-headers)
+
 (defun my-eww--inject-user-agent (orig-fun &rest args)
   "Set a User-Agent only when making requests from an EWW buffer."
   (if (derived-mode-p 'eww-mode)