fleet: send log counters in heartbeats and pull the text on demand

Heartbeats carry per-level counts, the most frequent log types (a stable hash of the message) and the newest id, no text. The node keeps its last 2048 lines; moshiro.logs.fetch lets the backend pull them. The log page pulls when it is open, and the backend pulls warnings and errors once a minute after a node reports an error.

backend/shared/MoShiro.Protocol/Rpc/MoShiroMethodTable.cs

@@ -19,6 +19,7 @@ public static class MoShiroMethodTable
                 MethodSpec.Request(MoShiroMethods.TestRun, RpcSide.Server),
                 MethodSpec.Request(MoShiroMethods.TestCancel, RpcSide.Server),
                 MethodSpec.Request(MoShiroMethods.DialerDisconnect, RpcSide.Server),
+                MethodSpec.Request(MoShiroMethods.LogsFetch, RpcSide.Server),
                 MethodSpec.Notification(MoShiroMethods.LinkRetry, RpcSide.Server),
                 MethodSpec.Notification(MoShiroMethods.UpdateOffer, RpcSide.Server),
                 MethodSpec.Notification(MoShiroMethods.UpdateApply, RpcSide.Server),

backend/shared/MoShiro.Protocol/Rpc/MoShiroRpc.cs

@@ -17,6 +17,7 @@ public static class MoShiroMethods
     public const string UpdateOffer = "moshiro.update.offer";
     public const string UpdateApply = "moshiro.update.apply";
     public const string Schedule = "moshiro.schedule";
+    public const string LogsFetch = "moshiro.logs.fetch";
 
     // 拨号方 ↔ 监听方（点对点会话）
     public const string Clock = "moshiro.clock";
@@ -338,11 +339,84 @@ public sealed class NodeHeartbeatExtra
     [JsonPropertyName("update")]
     public UpdateStatus? Update { get; set; }
 
-    [JsonPropertyName("runtime_logs")]
-    public List<NodeLogRecord>? RuntimeLogs { get; set; }
+    /// <summary>日志只报计数（不带文本）：自上次心跳以来各级别的条数、最多几个出现最多的类型，以及最新一条的编号；文本由 Backend 用 <c>moshiro.logs.fetch</c> 按需拉取。</summary>
+    [JsonPropertyName("log_summary")]
+    public LogSummaryDto? LogSummary { get; set; }
+}
 
-    [JsonPropertyName("dropped_runtime_logs")]
-    public long? DroppedRuntimeLogs { get; set; }
+/// <summary>某一类日志（消息文本的稳定哈希）在一个级别上出现了多少次。</summary>
+public sealed class LogTypeCountDto
+{
+    [JsonPropertyName("type")]
+    public uint Type { get; set; }
+
+    [JsonPropertyName("level")]
+    public string Level { get; set; } = "info";
+
+    [JsonPropertyName("count")]
+    public long Count { get; set; }
+}
+
+public sealed class LogSummaryDto
+{
+    [JsonPropertyName("last_id")]
+    public long LastId { get; set; }
+
+    [JsonPropertyName("info")]
+    public long Info { get; set; }
+
+    [JsonPropertyName("warn")]
+    public long Warn { get; set; }
+
+    [JsonPropertyName("error")]
+    public long Error { get; set; }
+
+    [JsonPropertyName("types")]
+    public List<LogTypeCountDto> Types { get; set; } = [];
+}
+
+/// <summary>Backend → 节点：拉取编号大于 <c>after_id</c> 的日志（最旧的在前），级别不低于 <c>min_level</c>。</summary>
+public sealed class LogsFetchParams
+{
+    [JsonPropertyName("after_id")]
+    public long AfterId { get; set; }
+
+    [JsonPropertyName("limit")]
+    public int Limit { get; set; } = 100;
+
+    [JsonPropertyName("min_level")]
+    public string? MinLevel { get; set; }
+}
+
+public sealed class LogEntryDto
+{
+    [JsonPropertyName("id")]
+    public long Id { get; set; }
+
+    [JsonPropertyName("type")]
+    public uint Type { get; set; }
+
+    [JsonPropertyName("at_utc_ms")]
+    public long AtUtcMs { get; set; }
+
+    [JsonPropertyName("level")]
+    public string Level { get; set; } = "info";
+
+    [JsonPropertyName("message")]
+    public string Message { get; set; } = "";
+
+    [JsonPropertyName("fields")]
+    public Dictionary<string, string> Fields { get; set; } = [];
+}
+
+public sealed class LogsFetchResult
+{
+    [JsonPropertyName("items")]
+    public List<LogEntryDto> Items { get; set; } = [];
+
+    /// <summary>节点上最新一条的编号：比 <c>after_id</c> 小说明节点重启过，编号从头开始。</summary>
+    [JsonPropertyName("last_id")]
+    public long LastId { get; set; }
 }
 
 /// <summary>
@@ -749,6 +823,9 @@ public static class FragmentKeys
 [JsonSerializable(typeof(DialTargets))]
 [JsonSerializable(typeof(UpdateOfferParams))]
 [JsonSerializable(typeof(ScheduleParams))]
+[JsonSerializable(typeof(LogsFetchParams))]
+[JsonSerializable(typeof(LogsFetchResult))]
+[JsonSerializable(typeof(LogSummaryDto))]
 [JsonSerializable(typeof(UpdateStatus))]
 [JsonSerializable(typeof(NodeHeartbeatExtra))]
 [JsonSerializable(typeof(NodeHelloMeta))]