fix(generator): don't re-inject the MCP route scaffold over live routes

lib/generators/docs_kit/install/install_generator.rb

@@ -150,7 +150,17 @@ def add_routes
       # bundled. A site opts in by adding `gem "mcp"` and uncommenting these. POST
       # speaks JSON-RPC; GET/DELETE 405 (read-only, stateless — no SSE session).
       # `route` prepends, so drawing `match` before `post` leaves `post` on top.
+      #
+      # Guarded on the endpoint (route_present?), NOT on Thor's byte-identical
+      # skip: a site that opted in has LIVE routes in its own style (an
+      # `, as: :mcp` suffix, single quotes) which never byte-match the commented
+      # template — plain `route` would re-inject the scaffold on every --sync.
+      # Found dogfooding 1.0.3 into pgbus + phlex-reactive.
       def add_mcp_route
+        if route_present?(%(post "/mcp" => "docs_kit/mcp#create"))
+          return say_status(:identical, "route /mcp (already drawn or scaffolded)", :blue)
+        end
+
         route %(# match "/mcp" => "docs_kit/mcp#method_not_allowed", via: %i[get delete])
         route %(# post "/mcp" => "docs_kit/mcp#create")
         route %(# Add your docs to an agent over MCP (needs `gem "mcp"`):)

spec/generators/install_generator_spec.rb

@@ -488,6 +488,25 @@ def capture_stream
       expect(routes).to include(%(# match "/mcp" => "docs_kit/mcp#method_not_allowed", via: %i[get delete]))
     end
 
+    it "does not re-inject the commented MCP scaffold when the site has LIVE /mcp routes" do
+      # A site that opted in (uncommented, in its own style — an `, as: :mcp`
+      # suffix) must not accumulate the commented scaffold on every --sync run.
+      # Found dogfooding 1.0.3 into pgbus + phlex-reactive.
+      write("config/routes.rb", <<~ROUTES)
+        Rails.application.routes.draw do
+          post "/mcp" => "docs_kit/mcp#create", as: :mcp
+          match "/mcp" => "docs_kit/mcp#method_not_allowed", via: %i[get delete]
+        end
+      ROUTES
+
+      run_generator(sync: true)
+
+      routes = read("config/routes.rb")
+      expect(routes).not_to include(%(# post "/mcp"))
+      expect(routes).not_to include(%(# match "/mcp"))
+      expect(routes.scan(%r{docs_kit/mcp#create}).size).to eq(1)
+    end
+
     it "draws /docs/search ABOVE docs/:doc so it isn't swallowed as :doc" do
       routes = read("config/routes.rb")