Fix critical issues in server process management

Critical fixes:
1. Fix PID parameter passing in stop_server/send_term_signal
   - Previously stop_server(pid) received parameter but used instance variable
   - Now consistently passes pid parameter through the call chain
   - Prevents potential bugs if pid values diverge

2. Fix HTTP timeout in readiness polling loop
   - Cap individual check timeout at 2 seconds max
   - Prevents 5s timeouts from blocking the 0.1s polling loop
   - Maintains responsiveness while supporting slow CI via configuration

3. Fix URI path handling edge case
   - Ensure GET path defaults to '/' if uri.path is empty
   - Prevents invalid HTTP requests with empty path

Documentation improvements:
- Document that @server_pgid may be nil in edge cases
- Clarify that 3xx redirects are considered valid "ready" state
- Add comments explaining timeout behavior in polling context

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

lib/cypress_on_rails/server.rb

@@ -113,6 +113,8 @@ def spawn_server
       begin
         @server_pgid = Process.getpgid(@server_pid)
       rescue Errno::ESRCH => e
+        # Edge case: process terminated before we could get pgid
+        # This is OK - send_term_signal will fall back to single-process kill
         CypressOnRails.configuration.logger.warn("Process #{@server_pid} terminated immediately after spawn: #{e.message}")
         @server_pgid = nil
       end
@@ -133,14 +135,18 @@ def wait_for_server(timeout = 30)
     def server_responding?
       config = CypressOnRails.configuration
       readiness_path = config.server_readiness_path || '/'
-      timeout = config.server_readiness_timeout || 5
+      # Use shorter timeout for individual readiness checks since we poll in a loop
+      # The configured timeout is for slow CI, but each check should be quick
+      timeout = [config.server_readiness_timeout || 5, 2].min
       uri = URI("http://#{host}:#{port}#{readiness_path}")
 
       response = Net::HTTP.start(uri.host, uri.port, open_timeout: timeout, read_timeout: timeout) do |http|
-        http.get(uri.path)
+        # Ensure path is never empty - default to '/'
+        http.get(uri.path.empty? ? '/' : uri.path)
       end
 
       # Accept 200-399 (success and redirects), reject 404 and 5xx
+      # 3xx redirects are considered "ready" because the server is responding correctly
       (200..399).cover?(response.code.to_i)
     rescue Errno::ECONNREFUSED, Errno::EADDRNOTAVAIL, Errno::ETIMEDOUT, SocketError,
            Net::OpenTimeout, Net::ReadTimeout, Net::HTTPBadResponse
@@ -151,21 +157,21 @@ def stop_server(pid)
       return unless pid
 
       puts "Stopping Rails server (PID: #{pid})"
-      send_term_signal
+      send_term_signal(pid)
       Process.wait(pid)
     rescue Errno::ESRCH
       # Process already terminated
     end
 
-    def send_term_signal
-      if @server_pgid && process_exists?(@server_pid)
+    def send_term_signal(pid)
+      if @server_pgid && process_exists?(pid)
         Process.kill('TERM', -@server_pgid)
       else
-        safe_kill_process('TERM', @server_pid)
+        safe_kill_process('TERM', pid)
       end
     rescue Errno::ESRCH, Errno::EPERM => e
       CypressOnRails.configuration.logger.warn("Failed to kill process group #{@server_pgid}: #{e.message}, trying single process")
-      safe_kill_process('TERM', @server_pid)
+      safe_kill_process('TERM', pid)
     end
 
     def process_exists?(pid)