feat: AI Agent Sandbox MCP Server v1を実装

Specifications、Design、ImplementationPlanの優先順位を整理し、単一Task実行モデル、typed option優先、設定可能なresource上限、local Ollamaを必須とするRelease Gateを文書化。

.NET 10/C# 14の5 production project、3 test project、E2E Clientを構築。typed YAML、en/ja locale、fixed/user prompt、stdioおよびloopback限定Streamable HTTP、agent_run/agent_status、Session、Ollama text/tool/Vision、TaskGraphとtoken accountingを実装。

Windows sandboxとしてfixed AppContainer、canonical/reparse検査、能力別ACL、path+SHA-256 executable approval、child-process restriction、Job Object、task journal、atomic file transaction、crash recoveryを実装。WFPのIPv4/IPv6 default denyとexact allow、dynamic session、temporary loopback exemption、管理者/BFE診断を追加。

Security/Recovery test、MCP/Ollama integration test、stdio/HTTP Operational E2E、Release Bundle生成・checksum・manifest・fresh extraction検査を追加。Requirement TraceabilityとPhase 0〜11の進捗、初回セットアップ可能なREADMEを整備。

Debug/Release/publish/objをrepository rootのbuild/へ集約し、旧project-local bin/objへの依存を除去。artifacts/とbuild/をGit管理外に設定し、clean checkoutでもsolution buildからE2E Clientまで生成可能にした。

1 files changed, 22 insertions, 0 deletions

diff --git a/src/Agent.Core/Tools/ToolUseGuard.cs b/src/Agent.Core/Tools/ToolUseGuard.cs
new file mode 100644
index 0000000..633d34c
--- /dev/null
+++ b/src/Agent.Core/Tools/ToolUseGuard.cs
@@ -0,0 +1,22 @@
+namespace Agent.Core.Tools;
+
+public enum ToolUseGuardDecision { Complete, Retry, Fail }
+
+public sealed record ToolUseGuardResult(ToolUseGuardDecision Decision, string Observation, int IdenticalFailureCount);
+
+public sealed class ToolUseGuard(int sameFailureLimit = 5)
+{
+    private readonly Dictionary<string, int> _failures = new(StringComparer.Ordinal);
+    public int SameFailureLimit { get; } = sameFailureLimit > 0 ? sameFailureLimit : throw new ArgumentOutOfRangeException(nameof(sameFailureLimit));
+
+    public ToolUseGuardResult Evaluate(bool requiresExternalEffect, bool hadToolCall, bool hasExternalEffectEvidence, string? failureFingerprint = null)
+    {
+        if (!requiresExternalEffect) return new(ToolUseGuardDecision.Complete, string.Empty, 0);
+        if (hasExternalEffectEvidence) return new(ToolUseGuardDecision.Complete, string.Empty, 0);
+        string fingerprint = string.IsNullOrWhiteSpace(failureFingerprint) ? "missing-external-effect" : failureFingerprint;
+        int count = _failures.TryGetValue(fingerprint, out int prior) ? prior + 1 : 1;
+        _failures[fingerprint] = count;
+        if (count >= SameFailureLimit) return new(ToolUseGuardDecision.Fail, "Required external effect was not completed after repeated identical failures.", count);
+        return new(ToolUseGuardDecision.Retry, "No verified external effect occurred; perform the required operation using an internal tool.", count);
+    }
+}