feat(mcp): migrate server to MCP 2026-07-28

Replace the MCP 1.4.1 stateful HTTP design with the official C# SDK 2.0.0 stateless transport. The SDK now owns protocol negotiation, server/discover, standard MCP headers, GET and DELETE handling, error serialization, caching hints, and legacy initialize compatibility; production code no longer maintains a custom wire-protocol workaround for MCP Inspector.

Separate transport state from application conversation state. HTTP does not issue Mcp-Session-Id, while the existing session_id remains an Agent conversation identifier. Preserve agent_run and agent_status for clients without Tasks support and add the official ModelContextProtocol.Extensions.Tasks 2.0.0 path for capable clients.

Add persistent MCP Task storage with atomic JSON replacement, user-only state location, configurable TTL and poll interval, restart recovery, cancellation correlation, and public Agent-to-MCP state mapping. Keep conformance-only tools and protocol exception fixtures in a test host so they cannot enter the Release Bundle.

Run administrator, BFE, WFP transaction, and filter add/delete preflight before binding. Fail fast with exit code 2 and actionable localized diagnostics when sandbox enforcement is unavailable. Emit ready only after the listener starts and keep stdio stdout protocol-pure.

Add shared rotating application and HTTP request logs. Record real socket endpoints, connection and trace identifiers, method, path, result, timing, media metadata, User-Agent, and MCP metadata. Do not trust X-Forwarded-For and do not log authorization, cookies, query data, request or response bodies, prompts, images, or Base64 payloads.

Add typed logging and Tasks configuration, Japanese and English messages, protocol and operations documentation, design/specification deltas, traceability, and exact conformance acquisition/offline runner scripts for @modelcontextprotocol/conformance 0.2.0-alpha.11. Node remains test-only and is not a runtime dependency.

Conformance evidence: server-stateless passed 28 of 28 checks with zero unexpected failures; DNS rebinding and multiple POST stream scenarios passed. The alpha Tasks lifecycle/cancel/error/required-task checks passed, while its wire-schema validator misclassifies CreateTaskResult and its MRTR composition remains incompatible with SDK 2.0.0. The aggregate conformance Gate is therefore recorded as PARTIAL, not PASS. Test-host fixture gaps for tools-list descriptions, JSON Schema diagnostics, caching fixtures, and a header-validation/required-Task capability conflict are also recorded without expected-failure masking.

Verification: Release build passed with 0 warnings and 0 errors; Planner tests 10/10 and Core tests 47/47 passed with skip 0. The last Windows suite run passed 19/25; five WFP cases require an elevated token and one symlink case requires unavailable host privilege, so the elevated security Gate remains open. A win-x64 self-contained 1.0.0 Bundle and ZIP were regenerated under build/Release/publish; runtime check was intentionally skipped in this non-elevated session. Evidence remains under ignored artifacts/evidence/mcp-2026-07-28.

Harden release regeneration when another shell holds the previous Bundle directory as its current directory: validate the target and remove only its children instead of deleting the directory itself. build/ and artifacts/ remain excluded from Git.

1 files changed, 18 insertions, 1 deletions

diff --git a/plans/RequirementTraceability.md b/plans/RequirementTraceability.md
index aec82a2..9d6e93b 100644
--- a/plans/RequirementTraceability.md
+++ b/plans/RequirementTraceability.md
@@ -57,10 +57,27 @@
 | Requirement | Evidence | Status |
 |---|---|---|
 | Release build | Release build warning 0/error 0 | PASS |
-| Unit/integration | Planner 10/10, Core 40/40, skip 0 | PASS |
+| Unit/integration | Planner 10/10, Core 47/47, skip 0 | PASS |
 | win-x64 self-contained Bundle | publish directory, ZIP, manifest, checksum | PASS |
 | Bundle-only elevated startup | `bundle-check.log`: administrator/BFE/WFP probe PASS | PASS |
 | E2E-01 stdio | `e2e-01-stdio.log`: local Ollama、read/edit/build/test、日本語、Audit、cleanup | PASS |
 | E2E-02 HTTP (`127.0.0.1`, `::1`) | `e2e-02-http-ipv4.log` / `e2e-02-http-ipv6.log` | PASS |
 | clean resource state | process/ACL/WFP/loopback/temp/journal/backup残留0 | PASS |
 | README-only fresh setup | ZIP fresh extraction、source参照0、README手順による最終runner | PASS |
+
+## MCP 2026-07-28 Migration
+
+| Requirement | Implementation / evidence | Status |
+|---|---|---|
+| SDK 2.0.0 / stateless discover | `Directory.Packages.props`, `McpHost`, official `server-stateless` evidence | PASS (28/28 core checks, unexpected failure 0) |
+| GET/DELETE 405、Legacy SSE無効、Session IDなし | `McpHttpTests` | PASS |
+| stdio / strict two Tool compatibility | test-only `Agent.Mcp.TestHost`, `McpStdioTests` | PASS |
+| official Tasks negotiation/lifecycle | `WithTasks`, `PersistentMcpTaskStore`, `McpHttpTests`, conformance Tasks evidence | PARTIAL: lifecycle/cancel/error/required-task PASS; MRTR fixture composition remains incompatible with alpha.11 |
+| Task persistence/restart/TTL | `PersistentMcpTaskStoreTests` | PASS |
+| CLI preflight / ready | `Program`, `McpHostLogObserver`, locale catalog | PASS (elevated live run required for final Gate) |
+| HTTP request log/redaction | `McpHostLogObserver`, `ObservabilityTests` | PASS |
+| conformance acquisition/offline runner | `Acquire-McpConformance.ps1`, `Run-McpConformance.ps1`, `Run-McpTasksConformance.ps1` | PASS |
+
+`0.2.0-alpha.11`のTasks extension scenarioはrelease requirementに含まれずinformationalとして実行され、正しい`CreateTaskResult`を通常`CallToolResult` schemaで検査する`wire-schema-valid`既知制約がある。これは`runner_limitations`へ分離し、application failureとは数えない。MRTR input/composition scenarioはSDK 2.0.0との組み合わせで未達のため、Tasks Extension GateはPASS扱いにしない。
+
+公式core runnerの個別結果では`server-stateless` 28/28、DNS rebinding、multiple POST streamがPASSした。一方、test-only conformance hostのfixture不足またはscenario間のcapability競合により、`tools-list`（description）、`json-schema-2020-12`（診断Tool）、`caching`（Prompt/Resource/Template）、`http-header-validation`（Tasks必須ToolをTasks非対応clientが呼ぶ組合せ）は未達である。production hostのexpected-failureとして隠さず、conformance総合GateはPARTIALのままとする。