Single-source the version from build.zig.zon

The version was declared twice: build.zig.zon, which `rake release` tags
from, and src/client.zig, which the `source` telemetry parameter reports
to serpapi.com. build.zig now imports the manifest and forwards
`.version` through a `build_options` module, so there is one place to
bump. A unit test checks the value parses as a semantic version.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: jvmvik

CHANGELOG.md

@@ -7,6 +7,9 @@
   agents, via the `output=md` format
 - `serpapi.Error` is exported from the module root
   (`serpapi.Error.SerpApiError`, previously only `serpapi.client.Error`)
+- `serpapi.version` is derived from `build.zig.zon` at build time instead
+  of being duplicated in `src/client.zig`, so the tag cut by `rake release`
+  and the version reported to serpapi.com cannot drift apart
 - Fix: the `timeout` option is enforced. It was accepted and documented
   but never applied, so a stalled connection blocked forever. Each request
   now races a timer on the client's `std.Io.Threaded` pool and is canceled

README.md

@@ -85,7 +85,10 @@ zig fetch --save 'https://github.com/serpapi/serpapi-zig/archive/refs/tags/v1.1.
 
 Released versions are listed on the
 [releases page](https://github.com/serpapi/serpapi-zig/releases); changes
-are recorded in [CHANGELOG.md](CHANGELOG.md).
+are recorded in [CHANGELOG.md](CHANGELOG.md). The version number lives in
+one place, `build.zig.zon`: `build.zig` forwards it to the library as
+`serpapi.version`, which is what the client reports to serpapi.com, and
+`rake release` reads it to name the tag.
 
 ## Simple Usage
 

build.zig

@@ -1,4 +1,5 @@
 const std = @import("std");
+const manifest = @import("build.zig.zon");
 
 pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
@@ -11,6 +12,12 @@ pub fn build(b: *std.Build) void {
         .optimize = optimize,
     });
 
+    // The library version reported to serpapi.com comes straight from the
+    // package manifest, so `rake release` and the `source` parameter agree.
+    const build_options = b.addOptions();
+    build_options.addOption([]const u8, "version", manifest.version);
+    mod.addOptions("build_options", build_options);
+
     // Unit tests: zig build test
     // the name also disambiguates kcov's per-binary report directories
     const mod_tests = b.addTest(.{ .name = "unit-tests", .root_module = mod });

src/client.zig

@@ -11,7 +11,8 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 
 /// Library version, reported to the backend through the `source` parameter.
-pub const version = "1.1.0";
+/// Single-sourced from `build.zig.zon` via `build.zig`.
+pub const version: []const u8 = @import("build_options").version;
 
 /// Backend service host.
 pub const backend = "serpapi.com";
@@ -574,6 +575,11 @@ pub const Client = struct {
 
 const testing = std.testing;
 
+test "version is the semantic version from build.zig.zon" {
+    const parsed = try std.SemanticVersion.parse(version);
+    try testing.expect(parsed.major >= 1);
+}
+
 test "constructor defaults" {
     var client = try Client.init(testing.allocator, .{});
     defer client.deinit();