fix(dashboard): add EMMS exclusion to recentf-exclude without clobbering it

dashboard-config used setq on recentf-exclude, discarding the five exclusions system-defaults adds earlier in init order (bookmarks, elpa, recentf, ElfeedDB, airootfs). Extract the EMMS exclusion into cj/--dashboard-exclude-emms-from-recentf (the :config side-effect was not reachable for a test) and use add-to-list so prior entries survive. Two ERT tests cover preservation and the added pattern.

3 files changed, 43 insertions, 3 deletions

diff --git a/modules/dashboard-config.el b/modules/dashboard-config.el
index b4e4545d..c70b78c2 100644
--- a/modules/dashboard-config.el
+++ b/modules/dashboard-config.el
@@ -145,6 +145,12 @@ window."
 ;; --------------------------------- Dashboard ---------------------------------
 ;; a useful startup screen for Emacs
 
+(defun cj/--dashboard-exclude-emms-from-recentf ()
+  "Exclude the EMMS history file from recentf.
+Adds to `recentf-exclude' so entries set elsewhere (e.g. in
+system-defaults) are preserved rather than overwritten."
+  (add-to-list 'recentf-exclude "/emms/history"))
+
 (use-package dashboard
   :demand t
   :hook (emacs-startup . cj/dashboard-only)
@@ -196,7 +202,7 @@ window."
   (setq dashboard-bookmarks-show-path nil)                            ;; don't show paths in bookmarks
   (setq dashboard-recentf-show-base t)                                ;; show filename, not full path
   (setq dashboard-recentf-item-format "%s")
-  (setq recentf-exclude '("/emms/history"))                            ;; exclude EMMS history from recent files
+  (cj/--dashboard-exclude-emms-from-recentf)                            ;; exclude EMMS history from recent files
   (setq dashboard-set-footer nil)                                     ;; don't show footer and quotes
 
   ;; == navigation
diff --git a/tests/test-dashboard-config-recentf-exclude.el b/tests/test-dashboard-config-recentf-exclude.el
new file mode 100644
index 00000000..f35b3eda
--- /dev/null
+++ b/tests/test-dashboard-config-recentf-exclude.el
@@ -0,0 +1,33 @@
+;;; test-dashboard-config-recentf-exclude.el --- recentf-exclude is not clobbered -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; `cj/--dashboard-exclude-emms-from-recentf' adds the EMMS history pattern
+;; to `recentf-exclude'.  It must ADD to the list, not replace it, or it
+;; wipes the exclusions system-defaults.el set earlier in init order
+;; (emacs_bookmarks, elpa, recentf, ElfeedDB, airootfs).
+
+;;; Code:
+
+(require 'ert)
+(require 'recentf)   ; makes `recentf-exclude' special so the let below is dynamic
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'testutil-general)
+(require 'dashboard-config)
+
+(ert-deftest test-dashboard-config-exclude-emms-preserves-existing-entries ()
+  "Error: excluding the EMMS history preserves prior recentf-exclude entries."
+  (let ((recentf-exclude (list "emacs_bookmarks" "airootfs")))
+    (cj/--dashboard-exclude-emms-from-recentf)
+    (should (member "/emms/history" recentf-exclude))
+    (should (member "emacs_bookmarks" recentf-exclude))
+    (should (member "airootfs" recentf-exclude))))
+
+(ert-deftest test-dashboard-config-exclude-emms-adds-the-pattern ()
+  "Normal: the EMMS history pattern is present after the call."
+  (let ((recentf-exclude nil))
+    (cj/--dashboard-exclude-emms-from-recentf)
+    (should (member "/emms/history" recentf-exclude))))
+
+(provide 'test-dashboard-config-recentf-exclude)
+;;; test-dashboard-config-recentf-exclude.el ends here
diff --git a/todo.org b/todo.org
index 1f565cbb..7516a8c0 100644
--- a/todo.org
+++ b/todo.org
@@ -780,8 +780,9 @@ Also =jumper.el:178= — the promised single-location toggle never toggles back
 ** TODO [#B] C-s C-s vertico-repeat path never works :bug:quick:solo:
 =modules/selection-framework.el:263= — =cj/consult-line-or-repeat= calls =vertico-repeat= on the second consecutive C-s, but nothing adds =vertico-repeat-save= to =minibuffer-setup-hook= (grep: zero hits config-wide), so it always signals "No Vertico session". Add the hook next to the vertico use-package block. From the 2026-06 config audit.
 
-** TODO [#B] dashboard-config setq wipes recentf-exclude list :bug:quick:solo:
-=modules/dashboard-config.el:199= =(setq recentf-exclude '("/emms/history"))= discards the five exclusions system-defaults.el:239-243 added earlier in init order (bookmarks, elpa, recentf, ElfeedDB, airootfs). Change to =add-to-list=. From the 2026-06 config audit.
+** DONE [#B] dashboard-config setq wipes recentf-exclude list :bug:quick:solo:
+CLOSED: [2026-06-12 Fri]
+Fixed in =modules/dashboard-config.el=: extracted the EMMS exclusion into =cj/--dashboard-exclude-emms-from-recentf= (the =:config= side-effect was not reachable for a test) and switched =setq= to =add-to-list=, so the five exclusions system-defaults adds earlier in init order survive. Two ERT tests in =tests/test-dashboard-config-recentf-exclude.el= (preserves prior entries / adds the pattern); the preservation test was red before, green after. Live-reloaded into the daemon and restored the five wiped entries in the running session.
 
 ** TODO [#B] auth-config: unguarded gpg-connect-agent call + compile-time require :bug:quick:solo:
 From the 2026-06 config audit. =modules/auth-config.el:88= — bare =(call-process "gpg-connect-agent" ...)= in a =:demand t= :config signals file-missing and aborts init on machines without the binary; guard with =cj/executable-find-or-warn=. =auth-config.el:36= — =user-constants= is required only =eval-when-compile= but =authinfo-file= is read at load time; works from .el source, fails from standalone .elc. Use a runtime require (system-defaults.el:32-35 documents this exact trap).