diff --git a/src/ClaudeDo.Worker/CLAUDE.md b/src/ClaudeDo.Worker/CLAUDE.md
index c1bec3fe..5b5036e2 100644
--- a/src/ClaudeDo.Worker/CLAUDE.md
+++ b/src/ClaudeDo.Worker/CLAUDE.md
@@ -256,4 +256,5 @@ list-only — there is no task-level override — and is written via `set_list_c
 - The worker runs standalone — start it separately from the UI. Loopback only (127.0.0.1).
 - `--permission-mode auto` by default; legacy `bypassPermissions` settings map to `auto` at dispatch time. `acceptEdits`, `plan`, `default` pass through unchanged.
 - Worktree branches follow `claudedo/{id}`.
+- **Both MCP servers run `Stateless = true`** (`Program.cs`). No `Mcp-Session-Id`, so a worker restart can't 404 a session that outlives it, and a 2026-07-28 client isn't refused back to the initialize handshake. The trade: **no** sampling, elicitation, resource subscriptions, unsolicited notifications, or legacy SSE endpoint — don't reach for those. In-tool progress notifications ride the POST's own response stream and work in both modes. All three consumers (`TaskRunner`, `PlanningSessionManager`, the installer's `RegisterMcpStep`) already use `type: "http"`.
 - **An MCP tool that can run longer than ~5s reports progress.** Staying silent lets the MCP client abort after 300s idle while the worker keeps working — the caller sees an abort even though the operation is still running. `Lifecycle/ProgressReporter` is the one implementation (elapsed-time reporting via `RunAsync`, per-item `i/n` via `ReportItem`) — thread an `IProgress<ProgressNotificationValue>? progress = null` parameter through instead of writing another polling loop.
diff --git a/src/ClaudeDo.Worker/Program.cs b/src/ClaudeDo.Worker/Program.cs
index db336c68..131778fa 100644
--- a/src/ClaudeDo.Worker/Program.cs
+++ b/src/ClaudeDo.Worker/Program.cs
@@ -201,7 +201,13 @@ builder.Services.AddScoped<PlanningMcpService>();
 builder.Services.AddScoped<FindingsStoreLocator>();
 builder.Services.AddScoped<TaskRunFindingsMcpTools>();
 builder.Services.AddMcpServer()
-    .WithHttpTransport()
+    // Stateless: no Mcp-Session-Id, so a worker restart doesn't 404 the sessions that
+    // outlive it (ConPTY tiles in the UI process, externally registered claude sessions),
+    // and a 2026-07-28 client isn't refused back to the initialize handshake. Nothing here
+    // needs the stateful-only features (sampling, elicitation, resource subscriptions,
+    // unsolicited notifications); in-tool progress works in both modes. Implies no legacy
+    // SSE endpoint — setting EnableLegacySse alongside this throws at startup.
+    .WithHttpTransport(o => o.Stateless = true)
     .WithTools<PlanningMcpService>()
     .WithTools<TaskRunMcpService>()
     .WithTools<TaskRunFindingsMcpTools>();
@@ -342,7 +348,7 @@ if (cfg.ExternalMcpPort > 0)
     externalBuilder.Services.AddScoped<FindingsStoreLocator>();
     externalBuilder.Services.AddScoped<FindingsMcpTools>();
     externalBuilder.Services.AddMcpServer()
-        .WithHttpTransport()
+        .WithHttpTransport(o => o.Stateless = true)
         .WithRequestFilters(f => f.AddCallToolFilter(ExternalMcpExceptionFilter.Wrap))
         .WithTools<ExternalMcpService>()
         .WithTools<BatchMcpTools>()