Add soversion, version macros, and reserved term_options words

The shared library now carries its major version in the SONAME
(libterm.so.0), so an ABI break gets a new file name. The header
gains TERM_VERSION, TERM_VERSION_MAJOR/MINOR/PATCH and
TERM_VERSION_CODE, and term_version() returns the code the library was
built with. A test checks the macros against meson.build's project
version and against the runtime value.

term_options ends with uint32_t reserved[8]. term_new() returns NULL if
a word is nonzero, so later versions can give those words a meaning
without misreading a caller's leftover data. All-zero options stay
valid.

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>

3 files changed, 60 insertions, 0 deletions

diff --git a/tests/meson.build b/tests/meson.build
index 69f3c49..5c77412 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -117,6 +117,17 @@ if cc.has_link_argument('-Wl,--wrap=realloc') and cc.has_link_argument('-Wl,--wr
     suite: 'unit',
   )
 endif
+
+# The project version comes in as a define, so the header macros cannot
+# drift from meson.build.
+version_test = executable('version-test', 'version_test.c',
+  c_args: test_c_args + ['-DTERM_TEST_PROJECT_VERSION="@0@"'.format(meson.project_version())],
+  dependencies: [term_internal_dep],
+)
+test('version-test', version_test,
+  env: test_env,
+  suite: 'unit',
+)
 test('term-cross-test', bash,
   args: [files('cross_test.sh'), meson.project_source_root()],
   suite: 'portability',
diff --git a/tests/term_test.c b/tests/term_test.c
index 66dbd96..2040e20 100644
--- a/tests/term_test.c
+++ b/tests/term_test.c
@@ -1832,8 +1832,30 @@ static void test_concurrent_feed_and_snapshot(void)
     term_free(t);
 }
 
+static void test_reserved_options_must_be_zero(void)
+{
+    struct term_options opt = { .size = { .x = 10, .y = 2 } };
+    struct term *t = term_new(&opt);
+    assert(t != NULL);
+    term_free(t);
+
+    size_t words = sizeof(opt.reserved) / sizeof(opt.reserved[0]);
+    for (size_t i = 0; i < words; i++) {
+        opt.reserved[i] = 1;
+        assert(term_new(&opt) == NULL);
+        opt.reserved[i] = 0;
+    }
+    opt.reserved[words - 1] = 0x80000000u;
+    assert(term_new(&opt) == NULL);
+    opt.reserved[words - 1] = 0;
+    t = term_new(&opt);
+    assert(t != NULL);
+    term_free(t);
+}
+
 int main(void)
 {
+    test_reserved_options_must_be_zero();
     test_concurrent_feed_and_snapshot();
     test_grow_past_reservation();
     test_skipped_cells_read_blank();
diff --git a/tests/version_test.c b/tests/version_test.c
new file mode 100644
index 0000000..0eb889e
--- /dev/null
+++ b/tests/version_test.c
@@ -0,0 +1,27 @@
+#include "term/term.h"
+
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+/* The project version from meson.build. The build defines it. */
+#ifndef TERM_TEST_PROJECT_VERSION
+#error "define TERM_TEST_PROJECT_VERSION as the project version, such as \"0.1.0\""
+#endif
+
+int main(void)
+{
+    char text[32];
+    snprintf(text, sizeof(text), "%d.%d.%d",
+        TERM_VERSION_MAJOR, TERM_VERSION_MINOR, TERM_VERSION_PATCH);
+    assert(!strcmp(text, TERM_TEST_PROJECT_VERSION));
+
+    int major, minor, patch;
+    assert(sscanf(TERM_TEST_PROJECT_VERSION, "%d.%d.%d", &major, &minor, &patch) == 3);
+    assert(TERM_VERSION_CODE == TERM_VERSION(major, minor, patch));
+    assert(term_version() == TERM_VERSION_CODE);
+
+    assert(TERM_VERSION(0, 2, 0) > TERM_VERSION(0, 1, 255));
+    assert(TERM_VERSION(1, 0, 0) > TERM_VERSION(0, 255, 255));
+    return 0;
+}