feat: add --version / -V flag

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added
+
+- `--version` / `-V` flag prints the CLI version (e.g. `mmcif-dict 0.3.0`) and
+  exits; the version is sourced from `build.zig.zon` via a build option so it
+  stays in sync with the release automatically (#36)
+
 ## [0.3.0] - 2026-04-16
 
 ### Removed

README.md

@@ -206,7 +206,8 @@ The runtime format is a zero-copy native binary (`.mdict`). Produce one with
 | `--json` | Output in JSON format |
 | `--dict PATH` | Path to dictionary (`.mdict`) |
 | `--name NAME` | Select named cache (default: `pdbx`) |
-| `--help` | Show usage |
+| `--version`, `-V` | Show version and exit |
+| `--help`, `-h` | Show usage |
 
 ## Environment Variables
 

build.zig

@@ -1,9 +1,15 @@
 const std = @import("std");
+const zon = @import("build.zig.zon");
 
 pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
 
+    // Expose the package version from build.zig.zon as a build option so the
+    // CLI can print it for --version without hardcoding the string twice.
+    const options = b.addOptions();
+    options.addOption([]const u8, "version", zon.version);
+
     const exe = b.addExecutable(.{
         .name = "mmcif-dict",
         .root_module = b.createModule(.{
@@ -12,6 +18,7 @@ pub fn build(b: *std.Build) void {
             .optimize = optimize,
         }),
     });
+    exe.root_module.addOptions("build_options", options);
     b.installArtifact(exe);
 
     const run_cmd = b.addRunArtifact(exe);

src/main.zig

@@ -1,4 +1,5 @@
 const std = @import("std");
+const build_options = @import("build_options");
 const dic_loader = @import("dic_loader.zig");
 const dict = @import("dict.zig");
 const fetch = @import("fetch.zig");
@@ -21,7 +22,8 @@ const usage =
     \\  --json                Output in JSON format
     \\  --dict PATH           Path to dictionary (.mdict)
     \\  --name NAME           Select named cache (default: pdbx)
-    \\  --help                Show this help
+    \\  --version, -V         Show version and exit
+    \\  --help, -h            Show this help
     \\
     \\Environment:
     \\  MMCIF_DICT_PATH       Default path to dictionary file (.mdict)
@@ -60,6 +62,10 @@ pub fn main() !void {
             try w.writeAll(usage);
             try w.flush();
             return;
+        } else if (std.mem.eql(u8, arg, "--version") or std.mem.eql(u8, arg, "-V")) {
+            try w.print("mmcif-dict {s}\n", .{build_options.version});
+            try w.flush();
+            return;
         } else if (std.mem.eql(u8, arg, "--dict")) {
             i += 1;
             if (i >= args.len) {

tests/test_smoke.py

@@ -199,5 +199,38 @@ def test_invalid_name_rejected() -> None:
     assert "invalid" in r.stderr.lower()
 
 
+def _expected_version() -> str:
+    """Parse the version string out of build.zig.zon without importing Zig."""
+    text = PROJECT_ROOT.joinpath("build.zig.zon").read_text()
+    for line in text.splitlines():
+        stripped = line.strip()
+        # Match `.version = "X"` exactly; reject siblings like `.version_foo`.
+        if stripped.startswith(".version") and "=" in stripped and '"' in stripped:
+            key = stripped.split("=", 1)[0].strip()
+            if key == ".version":
+                return stripped.split('"', 2)[1]
+    raise AssertionError("no .version line in build.zig.zon")
+
+
+def test_version_long_flag() -> None:
+    r = _run("--version")
+    assert r.returncode == 0, r.stderr
+    assert r.stdout.strip() == f"mmcif-dict {_expected_version()}"
+
+
+def test_version_short_flag() -> None:
+    r = _run("-V")
+    assert r.returncode == 0, r.stderr
+    assert r.stdout.strip() == f"mmcif-dict {_expected_version()}"
+
+
+def test_help_mentions_version_flag() -> None:
+    r = _run("--help")
+    assert r.returncode == 0, r.stderr
+    assert "--version" in r.stdout
+    # Guard against someone quietly dropping the short form from usage text.
+    assert "-V" in r.stdout
+
+
 if __name__ == "__main__":
     raise SystemExit(pytest.main([__file__, "-v"]))