feat(agenda): refresh the render cache on a timer, without the daemon

The surface reading this has to stay correct while Emacs is down, and
emacsclient is exactly the thing that cannot. So the writer is a batch
Emacs and a user timer runs it every five minutes.

- scripts/agenda-render-cache writes the cache from a batch Emacs. It
  resolves the agenda file list through the config's own resolver rather
  than restating it, so adding a calendar source stays a one-place change.
- The timer uses OnCalendar so Persistent actually applies. On a monotonic
  schedule it is silently ignored, and a machine that slept would come back
  to a stale file with nothing to trigger a catch-up.
- The window is now three days, yesterday through tomorrow. A consumer
  drawing a rolling window centred on now has nothing to draw for the part
  of its span outside today, which late in the evening is half the surface.

The keyword list moved to user-constants, where a batch Emacs can reach it
without this config's package dependencies. Without it org did not
recognise DOING or VERIFY, so it stopped parsing those headlines as tasks
at all: the keyword and priority cookie stayed glued to the front of every
title and each row reported no keyword and not-done. The file parsed
cleanly and was wrong, which is the failure worth guarding.

The bats tests run against a fixture and this checkout, not the machine's
real agenda and installed config. Asserting over live data let the same
suite pass on a day that happened to have no keyworded entries.

1 files changed, 50 insertions, 0 deletions

diff --git a/scripts/agenda-render-cache b/scripts/agenda-render-cache
new file mode 100755
index 00000000..b1e4d490
--- /dev/null
+++ b/scripts/agenda-render-cache
@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+# Write the agenda render cache for an external renderer.
+#
+# Runs a batch Emacs rather than talking to the daemon, because the surface
+# that reads the cache has to keep working while Emacs is down -- and
+# emacsclient is exactly the thing that cannot. Nothing here touches a running
+# Emacs, so it is safe to fire from a timer alongside an active session.
+#
+# The agenda file list is resolved the same way the editor resolves it, by
+# loading the config's own resolver rather than restating the list here. A
+# second copy of that list would drift the first time a calendar source is
+# added.
+#
+# Usage: agenda-render-cache
+# Env:   EMACS_D              -- config directory (default ~/.emacs.d)
+#        EMACS                -- emacs binary (default emacs)
+#        AGENDA_RENDER_FILES  -- colon-separated org files to read instead of
+#                                the configured agenda list. Lets a caller ask
+#                                about a known set, and lets the tests run
+#                                against a fixture rather than whatever happens
+#                                to be on the machine's real agenda today.
+
+set -euo pipefail
+
+EMACS_D="${EMACS_D:-$HOME/.emacs.d}"
+EMACS="${EMACS:-emacs}"
+
+if [ ! -d "$EMACS_D/modules" ]; then
+	echo "agenda-render-cache: no modules directory at $EMACS_D/modules" >&2
+	exit 1
+fi
+
+# -Q keeps the daemon's init out of it: this needs three modules, not a full
+# editor. load-prefer-newer stops a stale .elc from answering for changed
+# source, which would silently write yesterday's logic.
+exec "$EMACS" --batch -Q \
+	--eval '(setq load-prefer-newer t)' \
+	-L "$EMACS_D/modules" \
+	--eval '(progn
+                  (require (quote user-constants))
+                  (require (quote org-agenda-config))
+                  (setq org-todo-keywords cj/org-todo-keywords)
+                  (require (quote agenda-query))
+                  (setq org-agenda-files
+                        (let ((override (getenv "AGENDA_RENDER_FILES")))
+                          (if (and override (not (string-empty-p override)))
+                              (split-string override ":" t)
+                            (cj/--org-agenda-scan-files))))
+                  (princ (cj/agenda-render-cache-update))
+                  (terpri))'