feat: expose themeable faces for mode-line and buffer text

I added four customizable faces so themes and customize-face can restyle the text wttrin draws itself: wttrin-mode-line-stale (the dimmed stale mode-line emoji), wttrin-staleness-header (the "Last updated:" line), wttrin-instructions (the footer prose), and wttrin-key (the [a]/[g]/[q] chords).

The package exposed no faces before and hardcoded one color. The stale-emoji dimming used a literal "gray60". Now it inherits a face, so the color tracks the theme. I changed make-emoji-icon's second argument from a color string to a face symbol applied via :inherit.

wttrin-key inherits bold rather than help-key-binding, which is Emacs 28+ while the package supports 24.4.

The weather ASCII art stays colored by xterm-color's ANSI faces. Only the package's own text is newly faced.

5 files changed, 76 insertions, 20 deletions

diff --git a/tests/test-wttrin--add-buffer-instructions.el b/tests/test-wttrin--add-buffer-instructions.el
index 4949c45..0f1c382 100644
--- a/tests/test-wttrin--add-buffer-instructions.el
+++ b/tests/test-wttrin--add-buffer-instructions.el
@@ -73,6 +73,24 @@
             (setq count (1+ count))))
         (should (= 2 count))))))
 
+(ert-deftest test-wttrin--add-buffer-instructions-normal-key-chords-carry-key-face ()
+  "Bracketed key chords are styled with `wttrin-key'."
+  (with-temp-buffer
+    (wttrin--add-buffer-instructions)
+    (goto-char (point-min))
+    (search-forward "[a]")
+    ;; point is just after the closing bracket; the bracket char is part
+    ;; of the "[a]" segment
+    (should (eq (get-text-property (1- (point)) 'face) 'wttrin-key))))
+
+(ert-deftest test-wttrin--add-buffer-instructions-normal-prose-carries-instructions-face ()
+  "The footer prose is styled with `wttrin-instructions'."
+  (with-temp-buffer
+    (wttrin--add-buffer-instructions)
+    (goto-char (point-min))
+    (search-forward "Press:")
+    (should (eq (get-text-property (1- (point)) 'face) 'wttrin-instructions))))
+
 ;;; Boundary Cases
 
 (ert-deftest test-wttrin--add-buffer-instructions-boundary-point-at-beginning-appends-at-end ()
diff --git a/tests/test-wttrin--format-staleness-header.el b/tests/test-wttrin--format-staleness-header.el
index 5658be0..7a39b9a 100644
--- a/tests/test-wttrin--format-staleness-header.el
+++ b/tests/test-wttrin--format-staleness-header.el
@@ -50,6 +50,18 @@
             (should (string-match-p "just now" header)))))
     (test-wttrin--format-staleness-header-teardown)))
 
+(ert-deftest test-wttrin--format-staleness-header-normal-carries-face ()
+  "The returned header string is styled with `wttrin-staleness-header'."
+  (test-wttrin--format-staleness-header-setup)
+  (unwind-protect
+      (let ((now 1000000.0))
+        (cl-letf (((symbol-function 'float-time) (lambda () now)))
+          (testutil-wttrin-add-to-cache "Paris" "weather data" 300)
+          (let ((header (wttrin--format-staleness-header "Paris")))
+            (should (eq (get-text-property 0 'face header)
+                        'wttrin-staleness-header)))))
+    (test-wttrin--format-staleness-header-teardown)))
+
 ;;; Boundary Cases
 
 (ert-deftest test-wttrin--format-staleness-header-boundary-no-cache-returns-nil ()
diff --git a/tests/test-wttrin--mode-line-helpers.el b/tests/test-wttrin--mode-line-helpers.el
index 408711b..21ac167 100644
--- a/tests/test-wttrin--mode-line-helpers.el
+++ b/tests/test-wttrin--mode-line-helpers.el
@@ -46,40 +46,40 @@
         (should (equal (plist-get face :family) "Noto Color Emoji"))
         (should (equal (plist-get face :height) 1.0))))))
 
-(ert-deftest test-wttrin--make-emoji-icon-normal-with-foreground ()
-  "Foreground color should be applied when specified."
+(ert-deftest test-wttrin--make-emoji-icon-normal-with-face ()
+  "A face should be applied via :inherit when specified."
   (let ((wttrin-mode-line-emoji-font nil))
-    (let ((result (wttrin--make-emoji-icon "☀" "gray60")))
+    (let ((result (wttrin--make-emoji-icon "☀" 'wttrin-mode-line-stale)))
       (let ((face (get-text-property 0 'face result)))
-        (should (equal (plist-get face :foreground) "gray60"))))))
+        (should (eq (plist-get face :inherit) 'wttrin-mode-line-stale))))))
 
-(ert-deftest test-wttrin--make-emoji-icon-normal-with-font-and-foreground ()
-  "Both font and foreground should be applied together."
+(ert-deftest test-wttrin--make-emoji-icon-normal-with-font-and-face ()
+  "Both font and face should be applied together."
   (let ((wttrin-mode-line-emoji-font "Noto Color Emoji"))
-    (let ((result (wttrin--make-emoji-icon "⏳" "gray60")))
+    (let ((result (wttrin--make-emoji-icon "⏳" 'wttrin-mode-line-stale)))
       (let ((face (get-text-property 0 'face result)))
         (should (equal (plist-get face :family) "Noto Color Emoji"))
-        (should (equal (plist-get face :foreground) "gray60"))))))
+        (should (eq (plist-get face :inherit) 'wttrin-mode-line-stale))))))
 
 ;;; Boundary Cases
 
-(ert-deftest test-wttrin--make-emoji-icon-boundary-nil-foreground-no-color ()
-  "Nil foreground should not add any :foreground property when no font."
+(ert-deftest test-wttrin--make-emoji-icon-boundary-nil-face-no-font ()
+  "Nil face with no font should return a plain string."
   (let ((wttrin-mode-line-emoji-font nil))
     (let ((result (wttrin--make-emoji-icon "☀" nil)))
-      ;; Without font or foreground, should be plain string
+      ;; Without font or face, should be plain string
       (should (equal result "☀")))))
 
-(ert-deftest test-wttrin--make-emoji-icon-boundary-nil-foreground-with-font ()
-  "With font set and nil foreground, the face plist must omit :foreground entirely.
-A literal `:foreground nil' entry triggers \"Invalid face attribute\" warnings on
+(ert-deftest test-wttrin--make-emoji-icon-boundary-nil-face-with-font ()
+  "With font set and nil face, the face plist must omit :inherit entirely.
+A literal `:inherit nil' entry triggers \"Invalid face attribute\" warnings on
 every redisplay.  `plist-member' (not `plist-get') is required: `plist-get' can't
 distinguish a missing key from a present key bound to nil."
   (let ((wttrin-mode-line-emoji-font "Noto Color Emoji"))
     (let* ((result (wttrin--make-emoji-icon "☀" nil))
            (face (get-text-property 0 'face result)))
       (should (equal (plist-get face :family) "Noto Color Emoji"))
-      (should-not (plist-member face :foreground)))))
+      (should-not (plist-member face :inherit)))))
 
 ;;; --------------------------------------------------------------------------
 ;;; wttrin--set-mode-line-string
diff --git a/tests/test-wttrin--mode-line-update-display.el b/tests/test-wttrin--mode-line-update-display.el
index 0635b5f..721517e 100644
--- a/tests/test-wttrin--mode-line-update-display.el
+++ b/tests/test-wttrin--mode-line-update-display.el
@@ -170,7 +170,7 @@
     (test-wttrin--mode-line-update-display-teardown)))
 
 (ert-deftest test-wttrin--mode-line-update-display-stale-emoji-dimmed ()
-  "Stale data dims the emoji with gray foreground."
+  "Stale data dims the emoji via the `wttrin-mode-line-stale' face."
   (test-wttrin--mode-line-update-display-setup)
   (unwind-protect
       (let ((wttrin-mode-line-refresh-interval 900)
@@ -178,13 +178,13 @@
         (cl-letf (((symbol-function 'float-time) (lambda () 3000.0)))
           (setq wttrin--mode-line-cache (cons 1000.0 "Paris: X +61°F Clear"))
           (wttrin--mode-line-update-display)
-          ;; The emoji character should have a gray face
+          ;; The emoji character should inherit the stale face
           (let* ((str wttrin-mode-line-string)
                  ;; Find the emoji position (after the space)
                  (emoji-pos 1)
                  (face (get-text-property emoji-pos 'face str)))
             (should face)
-            (should (equal (plist-get face :foreground) "gray60")))))
+            (should (eq (plist-get face :inherit) 'wttrin-mode-line-stale)))))
     (test-wttrin--mode-line-update-display-teardown)))
 
 ;;; Boundary Cases
@@ -223,7 +223,7 @@ trigger an emoji re-render so dimming matches the tooltip's staleness state."
           (wttrin--mode-line-update-display)
           ;; Emoji should NOT be dimmed
           (let ((face (get-text-property 1 'face wttrin-mode-line-string)))
-            (should-not (and face (equal (plist-get face :foreground) "gray60")))))
+            (should-not (and face (eq (plist-get face :inherit) 'wttrin-mode-line-stale)))))
 
         ;; Time passes: data is now stale (age=2001, threshold=1800)
         ;; Invoke the tooltip (simulating a hover) — this should trigger a re-render
@@ -233,7 +233,7 @@ trigger an emoji re-render so dimming matches the tooltip's staleness state."
           ;; After hover detected staleness transition, emoji should now be dimmed
           (let ((face (get-text-property 1 'face wttrin-mode-line-string)))
             (should face)
-            (should (equal (plist-get face :foreground) "gray60")))))
+            (should (eq (plist-get face :inherit) 'wttrin-mode-line-stale)))))
     (test-wttrin--mode-line-update-display-teardown)))
 
 ;;; --------------------------------------------------------------------------
diff --git a/tests/test-wttrin-faces.el b/tests/test-wttrin-faces.el
new file mode 100644
index 0000000..db30002
--- /dev/null
+++ b/tests/test-wttrin-faces.el
@@ -0,0 +1,26 @@
+;;; test-wttrin-faces.el --- Tests for wttrin themeable faces -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2026 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests verifying the package's customizable faces are defined so
+;; themes and `customize-face' can target them.
+
+;;; Code:
+
+(require 'ert)
+(require 'wttrin)
+
+;;; Normal Cases
+
+(ert-deftest test-wttrin-faces-normal-all-defined ()
+  "Normal: every package face is defined after loading wttrin."
+  (dolist (face '(wttrin-mode-line-stale
+                  wttrin-staleness-header
+                  wttrin-instructions
+                  wttrin-key))
+    (should (facep face))))
+
+(provide 'test-wttrin-faces)
+;;; test-wttrin-faces.el ends here