sl0ppty: watch the config directory even when it is not there yet

You were right. The watch is on the *directory* -- editors write a new file
and rename it over the old one, so watching the file stops working the first
time you save -- but a directory that does not exist cannot be watched at
all. inotify_add_watch failed, the session gave up on watching for good, and
writing a config later did nothing until a restart. Which is exactly the
state a fresh machine is in, and exactly the state C-a e leaves you in.

sl0ppty creates its own config directory at startup now, so there is always
something to watch and a file appearing later is picked up. Tested from a home
directory with no .config at all.

Answering the other half of the question -- which settings actually reload --
turned up one that never worked at all: `shell`. main.c read $SHELL directly
and nobody read the config's value, so the setting parsed, rendered in
--dump-config, and did nothing. It is resolved per pane now, which fixes it and
makes it live: edit it, save, and the next pane you open uses it.

Everything else measured rather than assumed, and it is nearly everything:
colours, geometry, the status bar and line, frame marks, shader chains and
their states, and the keys including the leader itself. The two exceptions are
about *when* a value is read, not reluctance -- `shell` at pane creation, and
shader plugins which load on reload but never unload. Both are now written
down where someone would look.

One test needed rescuing from itself: it asserted the new leader worked by
splitting, in panes that were by then too narrow to split. A test that fails on
geometry while claiming to be about the prefix is worse than no test; it opens
a tab instead.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/server.c b/src/server.c
index 498b83f..242be26 100644
--- a/src/server.c
+++ b/src/server.c
@@ -239,6 +239,13 @@ int server_run(const char *name, const char *const argv[], uint16_t cols,
         snprintf(cfg_dir, sizeof cfg_dir, ".");
         snprintf(cfg_base, sizeof cfg_base, "%s", path);
       }
+      /* The watch is on the directory, not the file -- editors write a new
+       * file and rename it over the old one, so watching the file itself
+       * stops working the first time you save. But a directory that is not
+       * there cannot be watched at all, and then nothing is ever noticed for
+       * the life of the session: no config, no watch, and saving one later
+       * does nothing until a restart. Ours to create, so create it. */
+      path_mkdirs(cfg_dir);
       inofd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
       if (inofd >= 0) {
         inowd = inotify_add_watch(inofd, cfg_dir,