feat: --month [YYYY-MM | N] month overview

List a whole month, one line per day: weekday, day, liturgical colour and
celebration name. Form-aware; colours the name on a tty and prints the colour
word (aligned column) always, so a piped file stays readable. Defaults to the
current month; accepts YYYY-MM or a bare month number (current year).

Needs no scripture text, so it never loads or decompresses the text blob.
Days-in-month and weekday are computed with days_from_civil (leap-correct);
a month outside the compiled range is reported, not guessed. No table/data
change; OF and EF build clean under -Wall -Wextra; binary unchanged at 666 KB.

Claude-Session: https://claude.ai/code/session_01S1CD1u3tgSS4xNu6WHfp5a

2 files changed, 74 insertions, 5 deletions

diff --git a/README.md b/README.md
index 2fea861..eb763e2 100644
--- a/README.md
+++ b/README.md
@@ -18,14 +18,18 @@ the Go engine that computes and generates clectio's data.
     ./clectio 2026-12-25      # a given date
     ./clectio -g 2026-12-25   # the Gospel only
     ./clectio -a              # all readings (override a Gospel-only build)
+    ./clectio --month         # this month at a glance (day, colour, celebration)
+    ./clectio --month 2026-04 > apr.txt   # a month to a file for reference
     make install              # into $PREFIX/bin (default /usr/local)
 
 Needs only a C99 compiler and libc. It builds in about a second.
 
-The only run-time options are `-a`/`--all`, `-g`/`--gospel` (which reading set
-to print, overriding the compiled default) and `-h`/`--help`; everything else is
-compile-time. Reading text wraps to the terminal width by default (see `WRAP`);
-piped output is left one line per verse.
+The run-time options are `-a`/`--all`, `-g`/`--gospel` (which reading set to
+print, overriding the compiled default), `--month [YYYY-MM | N]` (one line per
+day of a month — weekday, colour and celebration, no readings; defaults to the
+current month) and `-h`/`--help`. Everything else is compile-time. Reading text
+wraps to the terminal width by default (see `WRAP`); piped output is left one
+line per verse.
 
 ## Configure (suckless style)
 
diff --git a/clectio.c b/clectio.c
index 72a1306..1839ade 100644
--- a/clectio.c
+++ b/clectio.c
@@ -107,6 +107,64 @@ static void putwrapped(const char *s, int w) {
 	}
 }
 
+/* One line per day of month `mon` in year `y`: weekday, day, colour, celebration.
+ * Needs no scripture text, so it never touches the text blob. Returns an exit
+ * code (1 if the month falls outside the compiled range). */
+static int print_month(int y, int mon) {
+	static const char *const wd[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
+	long base = days_from_civil(EPOCH_Y, EPOCH_M, EPOCH_D);
+	long civ1 = days_from_civil(y, (unsigned)mon, 1);
+	long nextfirst = days_from_civil(mon == 12 ? y + 1 : y, (unsigned)(mon == 12 ? 1 : mon + 1), 1);
+	int dim = (int)(nextfirst - civ1); /* days in the month (leap-correct) */
+	long off1 = civ1 - base;
+	int day, n;
+
+	if (off1 < 0 || off1 + dim - 1 >= NDAYS) {
+		fprintf(stderr, "clectio: %04d-%02d is outside the compiled range %d..%d\n",
+		        y, mon, EPOCH_Y, EPOCH_Y + (NDAYS / 366));
+		return 1;
+	}
+	n = printf("%04d-%02d  %s\n", y, mon, FORMNAME) - 1; /* underline that line */
+	while (n-- > 0)
+		putchar('=');
+	putchar('\n');
+	for (day = 1; day <= dim; day++) {
+		long civ = civ1 + (day - 1);
+		const Day *d = &days[cal[off1 + (day - 1)]];
+		int w = (int)((civ + 4) % 7); /* 1970-01-01 was Thursday; 0 = Sunday */
+		printf("%s %02d  %-6s  ", wd[w], day, colname[d->colour]);
+		if (usecolor)
+			printf("%s%s\033[0m\n", colansi[d->colour], names[d->name]);
+		else
+			printf("%s\n", names[d->name]);
+	}
+	return 0;
+}
+
+/* Parse a --month spec ("YYYY-MM", or "N" for month N of the current year, or
+ * NULL for the current month) and print it. Returns an exit code. */
+static int run_month(const char *spec) {
+	struct tm tm;
+	time_t t = time(NULL);
+	int y, mon;
+	localtime_r(&t, &tm);
+	y = tm.tm_year + 1900;
+	mon = tm.tm_mon + 1;
+	if (spec) {
+		int ok = strchr(spec, '-') ? sscanf(spec, "%d-%d", &y, &mon) == 2
+		                           : sscanf(spec, "%d", &mon) == 1;
+		if (!ok) {
+			fprintf(stderr, "clectio: bad month %s (want YYYY-MM or 1-12)\n", spec);
+			return 2;
+		}
+	}
+	if (mon < 1 || mon > 12) {
+		fprintf(stderr, "clectio: bad month %s (want YYYY-MM or 1-12)\n", spec ? spec : "");
+		return 2;
+	}
+	return print_month(y, mon);
+}
+
 static void print_day(long off, const char *datestr, int gospel, int wrap) {
 	const Day *d = &days[cal[off]];
 	unsigned ri;
@@ -137,7 +195,7 @@ int main(int argc, char **argv) {
 	int y, m, dd, i;
 	int gospel = GOSPEL_ONLY;    /* compiled default, overridable per run */
 	int istty = isatty(1);
-	int wrap;
+	int wrap, monthmode = 0;
 	const char *datearg = NULL;
 
 	usecolor = COLOR && istty;
@@ -146,8 +204,10 @@ int main(int argc, char **argv) {
 		if (!strcmp(argv[i], "-h") || !strcmp(argv[i], "--help")) {
 			fprintf(stderr,
 			        "usage: clectio [-a|--all | -g|--gospel] [YYYY-MM-DD]\n"
+			        "       clectio --month [YYYY-MM | N]\n"
 			        "  -a, --all      print all readings\n"
 			        "  -g, --gospel   print the Gospel only\n"
+			        "  --month        list a whole month (default: current month)\n"
 			        "  (default: today, %s)\n"
 			        "  compiled: %s, %s, wrap %s, range %d-%d\n",
 			        READMODE, FORMNAME, SIGLANAME, WRAPNAME, EPOCH_Y, EPOCH_Y + (NDAYS / 366));
@@ -156,6 +216,8 @@ int main(int argc, char **argv) {
 			gospel = 0;
 		} else if (!strcmp(argv[i], "-g") || !strcmp(argv[i], "--gospel")) {
 			gospel = 1;
+		} else if (!strcmp(argv[i], "--month")) {
+			monthmode = 1;
 		} else if (argv[i][0] == '-' && argv[i][1]) {
 			fprintf(stderr, "clectio: unknown option %s (try -h)\n", argv[i]);
 			return 2;
@@ -167,6 +229,9 @@ int main(int argc, char **argv) {
 		}
 	}
 
+	if (monthmode)
+		return run_month(datearg); /* month overview: no readings, no text loaded */
+
 	if (datearg) {
 		if (sscanf(datearg, "%d-%d-%d", &y, &m, &dd) != 3) {
 			fprintf(stderr, "clectio: bad date %s (want YYYY-MM-DD)\n", datearg);