Address PR review: pass raw socket to headers callback, use ok/err return conventionhttp-headers-callback

Rename response_headers to headers_callback, pass the raw connection as a
4th argument (for use cases like WebSocket upgrade handoff), and switch its
return contract to the idiomatic ok/err shape used elsewhere in this file:
truthy ok continues (optionally swapping in a new sink), falsy ok closes the
connection and propagates the callback's error via socket.protect instead of
faking a success return.

Claude-Session: https://claude.ai/code/session_01S4imKCU4hxDg96DXj9hxSB

1 files changed, 3 insertions, 7 deletions

diff --git a/src/http.lua b/src/http.lua
index 6cdc90a..3e2c789 100644
--- a/src/http.lua
+++ b/src/http.lua
@@ -360,7 +360,7 @@ local trequest, tredirect
         headers = reqt.headers,
         proxy = reqt.proxy,
         maxredirects = reqt.maxredirects,
-        response_headers = reqt.response_headers,
+        headers_callback = reqt.headers_callback,
         nredirects = (reqt.nredirects or 0) + 1,
         create = reqt.create
     }
@@ -405,12 +405,8 @@ end
     end
     -- here we are finally done
     -- provide an opportunity to abort or replace the sink based on the response headers
-    if nreqt.response_headers then
-        local abort, sink = nreqt.response_headers(code, headers, status)
-        if abort then
-            h:close()
-            return 1, code, headers, status
-        end
+    if nreqt.headers_callback then
+        local _, sink = h.try(nreqt.headers_callback(code, headers, status, h.c))
         if sink then
             nreqt.sink = sink
         end