feat: signed releases and a host-side updater for container nodes

CI signs the image digest of each agent and probe release; the panel only
stores and forwards it. Nodes write the manifest to their data directory and
a host updater verifies the signature with a local public key, pulls by
digest, restarts the unit and rolls back when it is unhealthy. The panel can
list releases, ask a node to update and show the reported update state.

backend/tests/Monitor.Backend.Tests/AgentHarness.cs

@@ -56,7 +56,7 @@ public sealed class AgentHarness : IAsyncDisposable
         };
         configure?.Invoke(config);
         LoadedNodeIdentity identity = LoadedNodeIdentity.Load(directory);
-        var app = new AgentApp(config, identity, TimeProvider.System, new ConsoleNodeLog(TimeProvider.System, Console.Out));
+        var app = new AgentApp(config, identity, directory, TimeProvider.System, new ConsoleNodeLog(TimeProvider.System, Console.Out));
         var harness = new AgentHarness(backend, directory, identity, app);
         await app.Ready.WaitAsync(TimeSpan.FromSeconds(10));
         await BackendFixture.EventuallyAsync(() => Task.FromResult(app.Link.IsConnected), because: "the agent should connect to the backend");

backend/tests/Monitor.Backend.Tests/UpdateTests.cs

@@ -0,0 +1,96 @@
+using System.Net;
+using System.Text.Json.Nodes;
+using Monitor.Protocol;
+using Monitor.TestSupport;
+
+namespace Monitor.Backend.Tests;
+
+[Collection("probe-e2e")]
+public sealed class UpdateTests
+{
+    private const string Digest = "sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
+
+    private readonly BackendFixture _backend;
+
+    public UpdateTests(BackendFixture backend)
+    {
+        _backend = backend;
+    }
+
+    // 面板不验签（节点宿主机上的更新器验），所以测试里签名随便写一个格式对的
+    private static string Manifest(string component, long seq, string digest = Digest) =>
+        $$"""{"schema":1,"component":"{{component}}","channel":"dev","image":"registry.example/monitor-dev/monitor-{{component}}","digest":"{{digest}}","tag":"dev-{{seq}}","version":"0.1.1","commit":"abc","built_at":"2026-10-06T00:00:00Z","seq":{{seq}}}""";
+
+    private async Task<HttpResponseMessage> PublishAsync(string manifest, string signature = "MEUCIQDc") =>
+        await _backend.Admin.PostAsync("/api/admin/releases", BackendFixture.Json(new JsonObject { ["manifest"] = manifest, ["signature"] = signature }));
+
+    [Fact]
+    public async Task Release_IsForwardedByteForByte_ToOnlineNodesOfThatComponent_AndToNodesThatConnectLater()
+    {
+        long seq = TimeProvider.System.GetUtcNow().ToUnixTimeSeconds() * 1000;
+        await using AgentSimulator online = await _backend.ConnectAgentAsync();
+        string manifest = Manifest("agent", seq);
+
+        using HttpResponseMessage published = await PublishAsync(manifest);
+        Assert.Equal(HttpStatusCode.Created, published.StatusCode);
+        JsonNode release = JsonNode.Parse(await published.Content.ReadAsStringAsync())!;
+        Assert.Equal("agent", release["component"]!.GetValue<string>());
+        Assert.Equal(Digest, release["digest"]!.GetValue<string>());
+
+        await BackendFixture.EventuallyAsync(() => Task.FromResult(online.UpdateOffers.ToArray().Any(o => o.Manifest == manifest && o.Signature == "MEUCIQDc")), because: "the offer reaches online agents unchanged");
+
+        // 之后才连上的节点，hello 之后补发
+        await using AgentSimulator late = await _backend.ConnectAgentAsync();
+        await BackendFixture.EventuallyAsync(() => Task.FromResult(late.UpdateOffers.ToArray().Any(o => o.Manifest == manifest)), because: "a node that connects later still gets the latest offer");
+
+        // 另一个组件（probe）的清单不会发给 Agent
+        using HttpResponseMessage probeRelease = await PublishAsync(Manifest("probe", seq));
+        Assert.Equal(HttpStatusCode.Created, probeRelease.StatusCode);
+        await Task.Delay(300);
+        Assert.DoesNotContain(online.UpdateOffers.ToArray(), o => o.Manifest.Contains("\"component\":\"probe\"", StringComparison.Ordinal));
+    }
+
+    [Fact]
+    public async Task Release_Registration_RefusesBadManifests_StaleSeq_AndNeedsAnAdmin()
+    {
+        long seq = TimeProvider.System.GetUtcNow().ToUnixTimeSeconds() * 1000 + 5;
+        Assert.Equal(HttpStatusCode.BadRequest, (await PublishAsync("{not json")).StatusCode);
+        Assert.Equal(HttpStatusCode.BadRequest, (await PublishAsync(Manifest("agent", seq, digest: "sha256:short"))).StatusCode);
+        Assert.Equal(HttpStatusCode.BadRequest, (await PublishAsync(Manifest("backend", seq))).StatusCode);
+        Assert.Equal(HttpStatusCode.BadRequest, (await PublishAsync(Manifest("agent", seq), signature: "not base64!")).StatusCode);
+
+        Assert.Equal(HttpStatusCode.Created, (await PublishAsync(Manifest("agent", seq))).StatusCode);
+        Assert.Equal(HttpStatusCode.Conflict, (await PublishAsync(Manifest("agent", seq))).StatusCode); // 同一个 seq：重放
+        Assert.Equal(HttpStatusCode.Conflict, (await PublishAsync(Manifest("agent", seq - 1))).StatusCode); // 更旧的 seq
+
+        using HttpResponseMessage anonymous = await _backend.Anonymous.PostAsync("/api/admin/releases", BackendFixture.Json(new JsonObject { ["manifest"] = Manifest("agent", seq + 1), ["signature"] = "MEUC" }));
+        Assert.Contains(anonymous.StatusCode, new[] { HttpStatusCode.Unauthorized, HttpStatusCode.Forbidden });
+    }
+
+    [Fact]
+    public async Task UpdateRequest_ReachesTheNode_AndItsReportedStatusShowsInBuildInfo()
+    {
+        await using AgentSimulator agent = await _backend.ConnectAgentAsync();
+        using HttpResponseMessage request = await _backend.Admin.PostAsync($"/api/admin/nodes/{agent.NodeId.Value}/update", null);
+        Assert.Equal(HttpStatusCode.NoContent, request.StatusCode);
+        await BackendFixture.EventuallyAsync(() => Task.FromResult(agent.UpdateApplies == 1));
+
+        // 节点（宿主机更新器）报告状态：面板在构建信息里显示
+        await agent.SendUpdateStatusAsync(new UpdateStatus { State = "available", Available = new UpdateAvailable { Tag = "dev-9", Version = "0.1.1", Digest = Digest, Seq = 9 }, At = TimeProvider.System.GetUtcNow().ToUnixTimeSeconds() });
+        await BackendFixture.EventuallyAsync(async () =>
+        {
+            JsonNode info = await _backend.GetJsonAsync(_backend.Admin, "/api/admin/build-info");
+            JsonNode? node = info["nodes"]!.AsArray().FirstOrDefault(n => n!["id"]!.GetValue<string>() == agent.NodeId.Value);
+            return node?["update"]?["state"]?.GetValue<string>() == "available" && node["update"]!["available_tag"]!.GetValue<string>() == "dev-9";
+        }, because: "the update state comes from the node's heartbeat");
+
+        // 节点离线之后不能请求更新
+        string id = agent.NodeId.Value;
+        await agent.DisposeAsync();
+        await BackendFixture.EventuallyAsync(async () =>
+        {
+            using HttpResponseMessage offline = await _backend.Admin.PostAsync($"/api/admin/nodes/{id}/update", null);
+            return offline.StatusCode == HttpStatusCode.Conflict || offline.StatusCode == HttpStatusCode.NotFound;
+        });
+    }
+}

backend/tests/Monitor.TestSupport/AgentSimulator.cs

@@ -48,6 +48,13 @@ public sealed class AgentSimulator : IAsyncDisposable
 
     public ConcurrentQueue<TestRunParams> TestRuns { get; } = new();
 
+    /// <summary>面板发来的发布清单（<c>monitor.update.offer</c>）和更新请求（<c>monitor.update.apply</c>）。</summary>
+    public ConcurrentQueue<UpdateOfferParams> UpdateOffers { get; } = new();
+
+    private int _updateApplies;
+
+    public int UpdateApplies => Volatile.Read(ref _updateApplies);
+
     public ConcurrentQueue<TestId> TestCancels { get; } = new();
 
     public IReadOnlyList<RejectedItem> RejectNextState { get; set; } = [];
@@ -188,6 +195,13 @@ public sealed class AgentSimulator : IAsyncDisposable
             new TestStatusParams { TestId = test, Status = status, Phase = phase, ErrorCode = errorCode },
             MonitorJsonContext.Default.TestStatusParams));
 
+    /// <summary>像节点的更新器报告的那样，随心跳上报更新状态。</summary>
+    public Task SendUpdateStatusAsync(UpdateStatus status) =>
+        SendAsync(RpcMessage.Notification(
+            FleetMethods.Heartbeat,
+            new HeartbeatParams { Extra = JsonSerializer.SerializeToElement(new AgentHeartbeatExtra { Update = status }, MonitorJsonContext.Default.AgentHeartbeatExtra) },
+            FleetRpcContext.Default.HeartbeatParams));
+
     public async Task<RpcMessage> RequestRawAsync(string method, JsonElement? parameters = null) => await RequestAsync(method, parameters);
 
     public async Task<TaskSet> WaitForTaskSetAsync(Func<TaskSet, bool> predicate, TimeSpan? timeout = null)
@@ -389,6 +403,12 @@ public sealed class AgentSimulator : IAsyncDisposable
             case FleetMethods.Revoked:
                 Revoked = true;
                 break;
+            case MonitorMethods.UpdateOffer:
+                UpdateOffers.Enqueue(message.Params!.Value.Deserialize(MonitorJsonContext.Default.UpdateOfferParams)!);
+                break;
+            case MonitorMethods.UpdateApply:
+                Interlocked.Increment(ref _updateApplies);
+                break;
             case MonitorMethods.TestRun:
                 TestRunParams run = message.Params!.Value.Deserialize(MonitorJsonContext.Default.TestRunParams)!;
                 TestRuns.Enqueue(run);