feat: specific error messages for fetch failures

Add HTTP status code checking (wttrin--extract-http-status) and pass
error descriptions through the callback chain so users see "Location
not found (HTTP 404)" or "Network error — check your connection"
instead of the generic "Perhaps the location was misspelled?" for
every failure.

Also fix pre-existing bug where the condition-case error handler in
extract-response-body killed an unrelated buffer after unwind-protect
already cleaned up.

330 tests (was 307), all passing.

1 files changed, 61 insertions, 0 deletions

diff --git a/tests/test-wttrin--extract-http-status.el b/tests/test-wttrin--extract-http-status.el
new file mode 100644
index 0000000..4a714e2
--- /dev/null
+++ b/tests/test-wttrin--extract-http-status.el
@@ -0,0 +1,61 @@
+;;; test-wttrin--extract-http-status.el --- Tests for wttrin--extract-http-status -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025-2026 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests for wttrin--extract-http-status function.
+;; Parses the HTTP status code from url-retrieve's response buffer.
+
+;;; Code:
+
+(require 'ert)
+(require 'wttrin)
+(require 'testutil-wttrin)
+
+;;; Normal Cases
+
+(ert-deftest test-wttrin--extract-http-status-normal-200 ()
+  "Standard 200 OK response should return 200."
+  (with-temp-buffer
+    (insert "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\nbody")
+    (should (= (wttrin--extract-http-status) 200))))
+
+(ert-deftest test-wttrin--extract-http-status-normal-404 ()
+  "404 Not Found response should return 404."
+  (with-temp-buffer
+    (insert "HTTP/1.1 404 Not Found\r\n\r\nNot found")
+    (should (= (wttrin--extract-http-status) 404))))
+
+(ert-deftest test-wttrin--extract-http-status-normal-500 ()
+  "500 Internal Server Error should return 500."
+  (with-temp-buffer
+    (insert "HTTP/1.1 500 Internal Server Error\r\n\r\nerror")
+    (should (= (wttrin--extract-http-status) 500))))
+
+;;; Boundary Cases
+
+(ert-deftest test-wttrin--extract-http-status-boundary-no-status-line ()
+  "Buffer with no HTTP status line should return nil."
+  (with-temp-buffer
+    (insert "just some text with no HTTP headers")
+    (should-not (wttrin--extract-http-status))))
+
+(ert-deftest test-wttrin--extract-http-status-boundary-http2 ()
+  "HTTP/2 responses use a different format but still have a status code."
+  (with-temp-buffer
+    (insert "HTTP/2 301 Moved Permanently\r\n\r\n")
+    (should (= (wttrin--extract-http-status) 301))))
+
+(ert-deftest test-wttrin--extract-http-status-boundary-does-not-move-point ()
+  "Parsing the status should not change point, so it doesn't interfere
+with subsequent header/body parsing."
+  (with-temp-buffer
+    (insert "HTTP/1.1 200 OK\r\n\r\nbody")
+    (goto-char (point-min))
+    (let ((pos-before (point)))
+      (wttrin--extract-http-status)
+      (should (= (point) pos-before)))))
+
+(provide 'test-wttrin--extract-http-status)
+;;; test-wttrin--extract-http-status.el ends here