fix: key the cache on the effective display optionsrelease/0.4.0

wttrin--make-cache-key used the raw wttrin-display-options, so turning wttrin-hide-follow-line on or off produced the same key. A cached location then kept serving the old buffer with the Follow line. Nothing refreshes a non-favorite location in the background, so it stayed wrong until a forced refresh or eviction. The key now uses wttrin--effective-display-options, the flags actually sent to wttr.in.

Two tests pin it: the toggle changes the key, and the toggle and an explicit F flag share one key because they send the same request.

2 files changed, 23 insertions, 2 deletions

diff --git a/tests/test-wttrin--make-cache-key.el b/tests/test-wttrin--make-cache-key.el
index 79c78d9..f1aca85 100644
--- a/tests/test-wttrin--make-cache-key.el
+++ b/tests/test-wttrin--make-cache-key.el
@@ -62,6 +62,25 @@ Without this, changing the forecast format keeps serving the old cached output."
     (should-not (string= a c))
     (should-not (string= b c))))
 
+;; wttrin-hide-follow-line changes the request (it adds the F flag), so it
+;; has to change the key too.  Keying on the raw options string missed it and
+;; served a cached buffer that still showed the Follow line.
+(ert-deftest test-wttrin--make-cache-key-boundary-hide-follow-line-changes-key ()
+  "Boundary: turning `wttrin-hide-follow-line' on or off yields a distinct key."
+  (let ((off (let ((wttrin-display-options nil) (wttrin-hide-follow-line nil))
+               (wttrin--make-cache-key "Paris")))
+        (on (let ((wttrin-display-options nil) (wttrin-hide-follow-line t))
+              (wttrin--make-cache-key "Paris"))))
+    (should-not (string= off on))))
+
+(ert-deftest test-wttrin--make-cache-key-boundary-equivalent-requests-share-key ()
+  "Boundary: the toggle and an explicit F flag send one request, so one key."
+  (let ((toggle (let ((wttrin-display-options nil) (wttrin-hide-follow-line t))
+                  (wttrin--make-cache-key "Paris")))
+        (flag (let ((wttrin-display-options "F") (wttrin-hide-follow-line nil))
+                (wttrin--make-cache-key "Paris"))))
+    (should (string= toggle flag))))
+
 (ert-deftest test-wttrin--make-cache-key-boundary-language-changes-key ()
   "Boundary: changing Accept-Language yields a distinct key."
   (let ((en (let ((wttrin-default-languages '("Accept-Language" . "en-US")))
diff --git a/wttrin.el b/wttrin.el
index bc67924..812a5a9 100644
--- a/wttrin.el
+++ b/wttrin.el
@@ -1522,10 +1522,12 @@ coordinates from a geolocation command."
 (defun wttrin--make-cache-key (location)
   "Create a cache key from LOCATION and every setting that shapes the response.
 Includes the unit system, display options, and Accept-Language, so changing any
-of them produces a distinct key rather than serving a stale-format response."
+of them produces a distinct key rather than serving a stale-format response.
+The display options are the effective ones sent to wttr.in, so
+`wttrin-hide-follow-line' changes the key and an equivalent request shares it."
   (format "%S" (list location
                       (or wttrin-unit-system "default")
-                      (or wttrin-display-options "")
+                      (wttrin--effective-display-options)
                       wttrin-default-languages)))
 
 (defun wttrin--get-cached-or-fetch (location callback)