feat: print build info at startup; version placeholders filled in by CI [CI SKIP]

backend/Directory.Build.props

@@ -13,7 +13,7 @@
     <UseArtifactsOutput>true</UseArtifactsOutput>
     <ArtifactsPath>$(MSBuildThisFileDirectory)artifacts</ArtifactsPath>
     <Deterministic>true</Deterministic>
-    <Version>0.4.0</Version>
+    <Version>0.0.0-dev</Version>
     <NuGetAudit>false</NuGetAudit>
   </PropertyGroup>
   <ItemGroup>

backend/agent/src/MoShiro.Agent/AgentApp.cs

@@ -143,6 +143,7 @@ public sealed class AgentApp : IDisposable
 
     public async Task RunAsync(CancellationToken ct)
     {
+        _log.Info("moshiro agent starting", MoShiro.Protocol.BuildInfo.Fields);
         using CancellationTokenSource linked = CancellationTokenSource.CreateLinkedTokenSource(ct);
         // 数据面和控制端口先开始监听，再连接 Backend：hello 里上报的是实际端口
         _udp.Bind();

backend/probe/src/MoShiro.Probe/ProbeApp.cs

@@ -103,6 +103,7 @@ public sealed class ProbeApp : IDisposable
 
     public async Task RunAsync(CancellationToken ct)
     {
+        _log.Info("moshiro probe starting", MoShiro.Protocol.BuildInfo.Fields);
         if (_env.Directory.Agents.Count == 0)
         {
             _log.Info("no agents known yet, waiting for the panel to send the list");

backend/shared/MoShiro.Protocol/BuildInfo.Summary.cs

@@ -0,0 +1,19 @@
+namespace MoShiro.Protocol;
+
+/// <summary>构建信息的人能读的形式（启动时打进日志）；常量部分由 MoShiro.Protocol.csproj 的 WriteBuildInfo 在构建时生成。</summary>
+public static partial class BuildInfo
+{
+    /// <summary>版本、tag、提交、构建时间的字段，没有的（本地构建不设环境变量）写 unknown。</summary>
+    public static (string Key, object? Value)[] Fields { get; } =
+    [
+        ("version", Or(Version)),
+        ("tag", Or(Tag)),
+        ("commit", Or(Commit)),
+        ("built_at", Or(BuiltAt)),
+    ];
+
+    /// <summary>一行摘要，例如：0.4.1-dev.2-a3338e1 (tag v0.4.1-dev.2-a3338e1, commit a3338e1b2c, built 2026-10-09T03:00:00Z)。</summary>
+    public static string Summary => $"{Or(Version)} (tag {Or(Tag)}, commit {Or(Commit)}, built {Or(BuiltAt)})";
+
+    private static string Or(string value) => string.IsNullOrWhiteSpace(value) ? "unknown" : value;
+}

backend/shared/MoShiro.Protocol/MoShiro.Protocol.csproj

@@ -18,7 +18,7 @@
     <ItemGroup>
       <BuildInfoLine Include="namespace MoShiro.Protocol%3B" />
       <BuildInfoLine Include="/// &lt;summary&gt;这个程序是什么时候、从哪个版本构建出来的（构建时生成）。&lt;/summary&gt;" />
-      <BuildInfoLine Include="public static class BuildInfo" />
+      <BuildInfoLine Include="public static partial class BuildInfo" />
       <BuildInfoLine Include="{" />
       <BuildInfoLine Include="    public const string Version = &quot;$(Version)&quot;%3B" />
       <BuildInfoLine Include="    public const string Tag = &quot;$(MOSHIRO_TAG)&quot;%3B" />

backend/src/MoShiro.Backend/Program.cs

@@ -1,3 +1,10 @@
 using MoShiro.Backend;
 
-await BackendHost.Build(args).RunAsync();
+WebApplication app = BackendHost.Build(args);
+// 启动时打一行构建信息：版本、tag、提交、构建时间（和 Agent、Probe 启动时打的是同一组）
+if (app.Logger.IsEnabled(LogLevel.Information))
+{
+    app.Logger.LogInformation("moshiro backend starting: version {BuildInfo}", MoShiro.Protocol.BuildInfo.Summary);
+}
+
+await app.RunAsync();