From b8704b0cb0efa868454b70e3f8e60fdbea9ec543 Mon Sep 17 00:00:00 2001
From: Santiago Bartesaghi <sbartesaghi@hotmail.com>
Date: Sun, 1 Mar 2026 19:07:05 -0300
Subject: [PATCH 1/3] Adjust examples

---
 examples/complex_llm_workflow/diagram.md   | 32 ------------------
 examples/complex_llm_workflow/generator.rb |  1 +
 examples/complex_workflow/diagram.html     | 25 +++++---------
 examples/complex_workflow/diagram.md       | 25 +++++---------
 examples/complex_workflow/generator.rb     |  1 +
 examples/parallel_workflow/diagram.html    | 38 ++++++++++++++++++++++
 examples/parallel_workflow/diagram.md      |  9 ++---
 examples/parallel_workflow/generator.rb    |  1 +
 examples/simple_workflow/diagram.html      | 38 ++++++++++++++++++++++
 examples/simple_workflow/diagram.md        | 13 +++++---
 examples/simple_workflow/generator.rb      |  1 +
 lib/mars/rendering/graph/builder.rb        |  8 ++++-
 lib/mars/rendering/mermaid.rb              | 13 +++++---
 13 files changed, 123 insertions(+), 82 deletions(-)
 delete mode 100644 examples/complex_llm_workflow/diagram.md
 create mode 100644 examples/parallel_workflow/diagram.html
 create mode 100644 examples/simple_workflow/diagram.html

diff --git a/examples/complex_llm_workflow/diagram.md b/examples/complex_llm_workflow/diagram.md
deleted file mode 100644
index 6051243..0000000
--- a/examples/complex_llm_workflow/diagram.md
+++ /dev/null
@@ -1,32 +0,0 @@
-```mermaid
-flowchart LR
-in((In))
-out((Out))
-agent1[Agent1]
-gate{Gate}
-parallel_workflow_aggregator[Parallel workflow Aggregator]
-agent2[Agent2]
-agent3[Agent3]
-agent4[Agent4]
-subgraph parallel_workflow["Parallel workflow"]
-  agent2
-  agent3
-  agent4
-end
-subgraph sequential_workflow["Sequential workflow"]
-  agent1
-  gate
-  parallel_workflow
-  parallel_workflow_aggregator
-end
-in --> agent1
-agent1 --> gate
-gate -->|failure| out
-gate --> agent2
-gate --> agent3
-gate --> agent4
-agent2 --> parallel_workflow_aggregator
-parallel_workflow_aggregator --> out
-agent3 --> parallel_workflow_aggregator
-agent4 --> parallel_workflow_aggregator
-```
diff --git a/examples/complex_llm_workflow/generator.rb b/examples/complex_llm_workflow/generator.rb
index 0bfe4b6..a8f8c8d 100755
--- a/examples/complex_llm_workflow/generator.rb
+++ b/examples/complex_llm_workflow/generator.rb
@@ -109,6 +109,7 @@ class WeatherStep < MARS::AgentStep
 # Generate and save the diagram
 diagram = MARS::Rendering::Mermaid.new(sequential_workflow).render
 File.write("examples/complex_llm_workflow/diagram.md", diagram)
+MARS::Rendering::Html.new(sequential_workflow).write("examples/complex_llm_workflow/diagram.html")
 puts "Complex workflow diagram saved to: examples/complex_llm_workflow/diagram.md"
 
 # Run the workflow
diff --git a/examples/complex_workflow/diagram.html b/examples/complex_workflow/diagram.html
index 53b7070..6b569a5 100644
--- a/examples/complex_workflow/diagram.html
+++ b/examples/complex_workflow/diagram.html
@@ -18,30 +18,21 @@ <h1>Main Pipeline</h1>
     const diagram = `flowchart LR
 in((In))
 out((Out))
-agent1[agent1]
-gate{Gate}
-agent4[agent4]
-parallel_workflow_aggregator[Parallel workflow Aggregator]
-agent2[agent2]
-agent3[agent3]
-parallel_workflow_2_aggregator[Parallel workflow 2 Aggregator]
-agent5[agent5]
 subgraph main_pipeline["Main Pipeline"]
-  agent1
-  gate
-  parallel_workflow_aggregator
+  agent1[agent1]
+  gate{Gate}
   subgraph parallel_workflow_2["Parallel workflow 2"]
     subgraph sequential_workflow["Sequential workflow"]
-      agent4
+      agent4[agent4]
       subgraph parallel_workflow["Parallel workflow"]
-        agent2
-        agent3
+        agent2[agent2]
+        agent3[agent3]
       end
-      parallel_workflow_aggregator
+      parallel_workflow_aggregator[Parallel workflow Aggregator]
     end
-    agent5
+    agent5[agent5]
   end
-  parallel_workflow_2_aggregator
+  parallel_workflow_2_aggregator[Parallel workflow 2 Aggregator]
 end
 in --> agent1
 agent1 --> gate
diff --git a/examples/complex_workflow/diagram.md b/examples/complex_workflow/diagram.md
index dd8fc85..7469b72 100644
--- a/examples/complex_workflow/diagram.md
+++ b/examples/complex_workflow/diagram.md
@@ -2,30 +2,21 @@
 flowchart LR
 in((In))
 out((Out))
-agent1[agent1]
-gate{Gate}
-agent4[agent4]
-parallel_workflow_aggregator[Parallel workflow Aggregator]
-agent2[agent2]
-agent3[agent3]
-parallel_workflow_2_aggregator[Parallel workflow 2 Aggregator]
-agent5[agent5]
 subgraph main_pipeline["Main Pipeline"]
-  agent1
-  gate
-  parallel_workflow_aggregator
+  agent1[agent1]
+  gate{Gate}
   subgraph parallel_workflow_2["Parallel workflow 2"]
     subgraph sequential_workflow["Sequential workflow"]
-      agent4
+      agent4[agent4]
       subgraph parallel_workflow["Parallel workflow"]
-        agent2
-        agent3
+        agent2[agent2]
+        agent3[agent3]
       end
-      parallel_workflow_aggregator
+      parallel_workflow_aggregator[Parallel workflow Aggregator]
     end
-    agent5
+    agent5[agent5]
   end
-  parallel_workflow_2_aggregator
+  parallel_workflow_2_aggregator[Parallel workflow 2 Aggregator]
 end
 in --> agent1
 agent1 --> gate
diff --git a/examples/complex_workflow/generator.rb b/examples/complex_workflow/generator.rb
index d32a2fa..9e39178 100755
--- a/examples/complex_workflow/generator.rb
+++ b/examples/complex_workflow/generator.rb
@@ -62,4 +62,5 @@ class Agent5 < MARS::AgentStep
 # Generate and save the diagram
 diagram = MARS::Rendering::Mermaid.new(main_workflow).render
 File.write("examples/complex_workflow/diagram.md", diagram)
+MARS::Rendering::Html.new(main_workflow).write("examples/complex_workflow/diagram.html")
 puts "Complex workflow diagram saved to: examples/complex_workflow/diagram.md"
diff --git a/examples/parallel_workflow/diagram.html b/examples/parallel_workflow/diagram.html
new file mode 100644
index 0000000..b8d26ac
--- /dev/null
+++ b/examples/parallel_workflow/diagram.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>Parallel workflow</title>
+  <style>
+    body { font-family: system-ui, sans-serif; margin: 2rem; background: #fafafa; }
+    h1 { color: #333; }
+    #diagram { background: white; padding: 2rem; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.1); }
+  </style>
+</head>
+<body>
+  <h1>Parallel workflow</h1>
+  <div id="diagram"></div>
+  <script type="module">
+    import { renderMermaidSVG } from "https://esm.sh/beautiful-mermaid@1";
+    const diagram = `flowchart LR
+in((In))
+out((Out))
+aggregator[Aggregator]
+subgraph parallel_workflow["Parallel workflow"]
+  agent1[agent1]
+  agent2[agent2]
+  agent3[agent3]
+end
+in --> agent1
+in --> agent2
+in --> agent3
+agent1 --> aggregator
+aggregator --> out
+agent2 --> aggregator
+agent3 --> aggregator`;
+    const svg = renderMermaidSVG(diagram);
+    document.getElementById("diagram").innerHTML = svg;
+  </script>
+</body>
+</html>
diff --git a/examples/parallel_workflow/diagram.md b/examples/parallel_workflow/diagram.md
index 8265347..6bbbaaf 100644
--- a/examples/parallel_workflow/diagram.md
+++ b/examples/parallel_workflow/diagram.md
@@ -3,13 +3,10 @@ flowchart LR
 in((In))
 out((Out))
 aggregator[Aggregator]
-agent1[Agent1]
-agent2[Agent2]
-agent3[Agent3]
 subgraph parallel_workflow["Parallel workflow"]
-  agent1
-  agent2
-  agent3
+  agent1[agent1]
+  agent2[agent2]
+  agent3[agent3]
 end
 in --> agent1
 in --> agent2
diff --git a/examples/parallel_workflow/generator.rb b/examples/parallel_workflow/generator.rb
index 66378bd..160fa11 100755
--- a/examples/parallel_workflow/generator.rb
+++ b/examples/parallel_workflow/generator.rb
@@ -30,4 +30,5 @@ class Agent3 < MARS::AgentStep
 # Generate and save the diagram
 diagram = MARS::Rendering::Mermaid.new(parallel_workflow).render
 File.write("examples/parallel_workflow/diagram.md", diagram)
+MARS::Rendering::Html.new(parallel_workflow).write("examples/parallel_workflow/diagram.html")
 puts "Parallel workflow diagram saved to: examples/parallel_workflow/diagram.md"
diff --git a/examples/simple_workflow/diagram.html b/examples/simple_workflow/diagram.html
new file mode 100644
index 0000000..1f9ffd9
--- /dev/null
+++ b/examples/simple_workflow/diagram.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>Main Pipeline</title>
+  <style>
+    body { font-family: system-ui, sans-serif; margin: 2rem; background: #fafafa; }
+    h1 { color: #333; }
+    #diagram { background: white; padding: 2rem; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.1); }
+  </style>
+</head>
+<body>
+  <h1>Main Pipeline</h1>
+  <div id="diagram"></div>
+  <script type="module">
+    import { renderMermaidSVG } from "https://esm.sh/beautiful-mermaid@1";
+    const diagram = `flowchart LR
+in((In))
+out((Out))
+subgraph main_pipeline["Main Pipeline"]
+  agent1[agent1]
+  gate{Gate}
+end
+subgraph success_workflow["Success workflow"]
+  agent2[agent2]
+  agent3[agent3]
+end
+in --> agent1
+agent1 --> gate
+gate -->|success| agent2
+agent2 --> agent3
+agent3 --> out`;
+    const svg = renderMermaidSVG(diagram);
+    document.getElementById("diagram").innerHTML = svg;
+  </script>
+</body>
+</html>
diff --git a/examples/simple_workflow/diagram.md b/examples/simple_workflow/diagram.md
index 4bab18d..5891e06 100644
--- a/examples/simple_workflow/diagram.md
+++ b/examples/simple_workflow/diagram.md
@@ -2,14 +2,17 @@
 flowchart LR
 in((In))
 out((Out))
-agent1[Agent1]
-gate{Gate}
-agent2[Agent2]
-agent3[Agent3]
+subgraph main_pipeline["Main Pipeline"]
+  agent1[agent1]
+  gate{Gate}
+end
+subgraph success_workflow["Success workflow"]
+  agent2[agent2]
+  agent3[agent3]
+end
 in --> agent1
 agent1 --> gate
 gate -->|success| agent2
-gate -->|default| out
 agent2 --> agent3
 agent3 --> out
 ```
diff --git a/examples/simple_workflow/generator.rb b/examples/simple_workflow/generator.rb
index b1a0351..60bde50 100755
--- a/examples/simple_workflow/generator.rb
+++ b/examples/simple_workflow/generator.rb
@@ -41,4 +41,5 @@ class Agent3 < MARS::AgentStep
 # Generate and save the diagram
 diagram = MARS::Rendering::Mermaid.new(main_workflow).render
 File.write("examples/simple_workflow/diagram.md", diagram)
+MARS::Rendering::Html.new(main_workflow).write("examples/simple_workflow/diagram.html")
 puts "Simple workflow diagram saved to: examples/simple_workflow/diagram.md"
diff --git a/lib/mars/rendering/graph/builder.rb b/lib/mars/rendering/graph/builder.rb
index 9e5db74..5598570 100644
--- a/lib/mars/rendering/graph/builder.rb
+++ b/lib/mars/rendering/graph/builder.rb
@@ -33,10 +33,16 @@ def add_subgraph(id, name)
         end
 
         def add_node_to_subgraph(id, node_id)
-          return if subgraphs[id]&.nodes&.include?(node_id)
+          return if node_in_any_subgraph?(node_id)
 
           subgraphs[id].nodes << node_id
         end
+
+        private
+
+        def node_in_any_subgraph?(node_id)
+          subgraphs.values.any? { |sg| sg.nodes.include?(node_id) }
+        end
       end
     end
   end
diff --git a/lib/mars/rendering/mermaid.rb b/lib/mars/rendering/mermaid.rb
index 3f1914a..ef5cf57 100644
--- a/lib/mars/rendering/mermaid.rb
+++ b/lib/mars/rendering/mermaid.rb
@@ -23,11 +23,16 @@ def render(options = {})
       end
 
       def graph_mermaid
-        nodes_mermaid + subgraphs_mermaid + edges_mermaid
+        top_level_nodes_mermaid + subgraphs_mermaid + edges_mermaid
       end
 
-      def nodes_mermaid
-        nodes.keys.map { |node_id| "#{node_id}#{shape(node_id)}" }
+      def top_level_nodes_mermaid
+        subgraph_node_ids = subgraphs.values.flat_map(&:nodes).to_set
+        nodes.keys.reject { |id| subgraph_node_ids.include?(id) }.map { |id| node_definition(id) }
+      end
+
+      def node_definition(node_id)
+        "#{node_id}#{shape(node_id)}"
       end
 
       def subgraphs_mermaid
@@ -87,7 +92,7 @@ def render_subgraph_node(node_id, indent)
         if subgraphs.key?(node_id)
           render_subgraph(node_id, "#{indent}  ")
         else
-          "#{indent}  #{node_id}"
+          "#{indent}  #{node_definition(node_id)}"
         end
       end
     end

From 36dde677c1c1ff5ec7d8b474fff89ab791337f32 Mon Sep 17 00:00:00 2001
From: Santiago Bartesaghi <sbartesaghi@hotmail.com>
Date: Mon, 2 Mar 2026 10:44:57 -0300
Subject: [PATCH 2/3] Silence warning

---
 lib/mars.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/mars.rb b/lib/mars.rb
index 4d0dffd..19a0cf2 100644
--- a/lib/mars.rb
+++ b/lib/mars.rb
@@ -7,6 +7,7 @@
 
 loader = Zeitwerk::Loader.for_gem
 loader.inflector.inflect("mars" => "MARS")
+loader.ignore("#{__dir__}/mars_rb.rb")
 loader.setup
 
 module MARS

From 9cf5ad6b1017b8348cf427979e9aff8320b1df96 Mon Sep 17 00:00:00 2001
From: Santiago Bartesaghi <sbartesaghi@hotmail.com>
Date: Mon, 2 Mar 2026 11:37:10 -0300
Subject: [PATCH 3/3] Improvements

---
 examples/complex_llm_workflow/diagram.html    | 45 +++++++++++++++++++
 examples/complex_llm_workflow/diagram.md      | 25 +++++++++++
 examples/complex_llm_workflow/generator.rb    |  3 +-
 examples/complex_workflow/diagram.html        |  3 +-
 examples/complex_workflow/diagram.md          |  3 +-
 examples/complex_workflow/generator.rb        |  3 +-
 examples/parallel_workflow/generator.rb       |  3 +-
 examples/simple_workflow/generator.rb         |  3 +-
 lib/mars/rendering/graph/builder.rb           | 24 +++++++++-
 .../rendering/graph/sequential_workflow.rb    | 19 ++++++--
 10 files changed, 117 insertions(+), 14 deletions(-)
 create mode 100644 examples/complex_llm_workflow/diagram.html
 create mode 100644 examples/complex_llm_workflow/diagram.md

diff --git a/examples/complex_llm_workflow/diagram.html b/examples/complex_llm_workflow/diagram.html
new file mode 100644
index 0000000..90467eb
--- /dev/null
+++ b/examples/complex_llm_workflow/diagram.html
@@ -0,0 +1,45 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>Sequential workflow</title>
+  <style>
+    body { font-family: system-ui, sans-serif; margin: 2rem; background: #fafafa; }
+    h1 { color: #333; }
+    #diagram { background: white; padding: 2rem; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.1); }
+  </style>
+</head>
+<body>
+  <h1>Sequential workflow</h1>
+  <div id="diagram"></div>
+  <script type="module">
+    import { renderMermaidSVG } from "https://esm.sh/beautiful-mermaid@1";
+    const diagram = `flowchart LR
+in((In))
+out((Out))
+subgraph sequential_workflow["Sequential workflow"]
+  country[Country]
+  gate{Gate}
+  subgraph parallel_workflow["Parallel workflow"]
+    food[Food]
+    sports[Sports]
+    weather[Weather]
+  end
+  parallel_workflow_aggregator[Parallel workflow Aggregator]
+end
+in --> country
+country --> gate
+gate -->|failure| out
+gate --> food
+gate --> sports
+gate --> weather
+food --> parallel_workflow_aggregator
+parallel_workflow_aggregator --> out
+sports --> parallel_workflow_aggregator
+weather --> parallel_workflow_aggregator`;
+    const svg = renderMermaidSVG(diagram);
+    document.getElementById("diagram").innerHTML = svg;
+  </script>
+</body>
+</html>
diff --git a/examples/complex_llm_workflow/diagram.md b/examples/complex_llm_workflow/diagram.md
new file mode 100644
index 0000000..eb60ca2
--- /dev/null
+++ b/examples/complex_llm_workflow/diagram.md
@@ -0,0 +1,25 @@
+```mermaid
+flowchart LR
+in((In))
+out((Out))
+subgraph sequential_workflow["Sequential workflow"]
+  country[Country]
+  gate{Gate}
+  subgraph parallel_workflow["Parallel workflow"]
+    food[Food]
+    sports[Sports]
+    weather[Weather]
+  end
+  parallel_workflow_aggregator[Parallel workflow Aggregator]
+end
+in --> country
+country --> gate
+gate -->|failure| out
+gate --> food
+gate --> sports
+gate --> weather
+food --> parallel_workflow_aggregator
+parallel_workflow_aggregator --> out
+sports --> parallel_workflow_aggregator
+weather --> parallel_workflow_aggregator
+```
diff --git a/examples/complex_llm_workflow/generator.rb b/examples/complex_llm_workflow/generator.rb
index a8f8c8d..b23492d 100755
--- a/examples/complex_llm_workflow/generator.rb
+++ b/examples/complex_llm_workflow/generator.rb
@@ -109,8 +109,9 @@ class WeatherStep < MARS::AgentStep
 # Generate and save the diagram
 diagram = MARS::Rendering::Mermaid.new(sequential_workflow).render
 File.write("examples/complex_llm_workflow/diagram.md", diagram)
-MARS::Rendering::Html.new(sequential_workflow).write("examples/complex_llm_workflow/diagram.html")
 puts "Complex workflow diagram saved to: examples/complex_llm_workflow/diagram.md"
+MARS::Rendering::Html.new(sequential_workflow).write("examples/complex_llm_workflow/diagram.html")
+puts "Complex workflow beautiful mermaid diagram saved to: examples/complex_llm_workflow/diagram.html"
 
 # Run the workflow
 puts sequential_workflow.run("Which is the largest country in Europe?")
diff --git a/examples/complex_workflow/diagram.html b/examples/complex_workflow/diagram.html
index 6b569a5..3da8bb0 100644
--- a/examples/complex_workflow/diagram.html
+++ b/examples/complex_workflow/diagram.html
@@ -39,12 +39,11 @@ <h1>Main Pipeline</h1>
 gate -->|warning| agent4
 gate -->|error| agent2
 gate -->|error| agent3
-gate --> agent4
-gate --> agent5
 agent4 --> agent2
 agent4 --> agent3
 agent2 --> parallel_workflow_aggregator
 parallel_workflow_aggregator --> parallel_workflow_2_aggregator
+parallel_workflow_aggregator --> agent5
 agent3 --> parallel_workflow_aggregator
 parallel_workflow_2_aggregator --> out
 agent5 --> parallel_workflow_2_aggregator`;
diff --git a/examples/complex_workflow/diagram.md b/examples/complex_workflow/diagram.md
index 7469b72..c95456d 100644
--- a/examples/complex_workflow/diagram.md
+++ b/examples/complex_workflow/diagram.md
@@ -23,12 +23,11 @@ agent1 --> gate
 gate -->|warning| agent4
 gate -->|error| agent2
 gate -->|error| agent3
-gate --> agent4
-gate --> agent5
 agent4 --> agent2
 agent4 --> agent3
 agent2 --> parallel_workflow_aggregator
 parallel_workflow_aggregator --> parallel_workflow_2_aggregator
+parallel_workflow_aggregator --> agent5
 agent3 --> parallel_workflow_aggregator
 parallel_workflow_2_aggregator --> out
 agent5 --> parallel_workflow_2_aggregator
diff --git a/examples/complex_workflow/generator.rb b/examples/complex_workflow/generator.rb
index 9e39178..aa36cfb 100755
--- a/examples/complex_workflow/generator.rb
+++ b/examples/complex_workflow/generator.rb
@@ -62,5 +62,6 @@ class Agent5 < MARS::AgentStep
 # Generate and save the diagram
 diagram = MARS::Rendering::Mermaid.new(main_workflow).render
 File.write("examples/complex_workflow/diagram.md", diagram)
-MARS::Rendering::Html.new(main_workflow).write("examples/complex_workflow/diagram.html")
 puts "Complex workflow diagram saved to: examples/complex_workflow/diagram.md"
+MARS::Rendering::Html.new(main_workflow).write("examples/complex_workflow/diagram.html")
+puts "Complex workflow beautiful mermaid diagram saved to: examples/complex_workflow/diagram.html"
diff --git a/examples/parallel_workflow/generator.rb b/examples/parallel_workflow/generator.rb
index 160fa11..1cc3992 100755
--- a/examples/parallel_workflow/generator.rb
+++ b/examples/parallel_workflow/generator.rb
@@ -30,5 +30,6 @@ class Agent3 < MARS::AgentStep
 # Generate and save the diagram
 diagram = MARS::Rendering::Mermaid.new(parallel_workflow).render
 File.write("examples/parallel_workflow/diagram.md", diagram)
-MARS::Rendering::Html.new(parallel_workflow).write("examples/parallel_workflow/diagram.html")
 puts "Parallel workflow diagram saved to: examples/parallel_workflow/diagram.md"
+MARS::Rendering::Html.new(parallel_workflow).write("examples/parallel_workflow/diagram.html")
+puts "Parallel workflow beautiful mermaid diagram saved to: examples/parallel_workflow/diagram.html"
diff --git a/examples/simple_workflow/generator.rb b/examples/simple_workflow/generator.rb
index 60bde50..60e246f 100755
--- a/examples/simple_workflow/generator.rb
+++ b/examples/simple_workflow/generator.rb
@@ -41,5 +41,6 @@ class Agent3 < MARS::AgentStep
 # Generate and save the diagram
 diagram = MARS::Rendering::Mermaid.new(main_workflow).render
 File.write("examples/simple_workflow/diagram.md", diagram)
-MARS::Rendering::Html.new(main_workflow).write("examples/simple_workflow/diagram.html")
 puts "Simple workflow diagram saved to: examples/simple_workflow/diagram.md"
+MARS::Rendering::Html.new(main_workflow).write("examples/simple_workflow/diagram.html")
+puts "Simple workflow beautiful mermaid diagram saved to: examples/simple_workflow/diagram.html"
diff --git a/lib/mars/rendering/graph/builder.rb b/lib/mars/rendering/graph/builder.rb
index 5598570..4778ab4 100644
--- a/lib/mars/rendering/graph/builder.rb
+++ b/lib/mars/rendering/graph/builder.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "set"
+
 module MARS
   module Rendering
     module Graph
@@ -14,9 +16,10 @@ def initialize
 
         def add_edge(from, to, value = nil)
           return unless from && to
+          return if adjacency[from].include?([to, value])
+          return if reachable?(to, from)
 
-          # can we avoid visiting the node twice instead?
-          adjacency[from] << [to, value] unless adjacency[from].include?([to, value])
+          adjacency[from] << [to, value]
           adjacency[to] = [] unless adjacency[to]
         end
 
@@ -43,6 +46,23 @@ def add_node_to_subgraph(id, node_id)
         def node_in_any_subgraph?(node_id)
           subgraphs.values.any? { |sg| sg.nodes.include?(node_id) }
         end
+
+        def reachable?(from, target)
+          visited = Set.new
+          queue = [from]
+
+          while queue.any?
+            current = queue.shift
+            next if visited.include?(current)
+
+            visited << current
+            return true if current == target
+
+            adjacency[current]&.each { |(to, _)| queue << to }
+          end
+
+          false
+        end
       end
     end
   end
diff --git a/lib/mars/rendering/graph/sequential_workflow.rb b/lib/mars/rendering/graph/sequential_workflow.rb
index 69450f7..fef99a3 100644
--- a/lib/mars/rendering/graph/sequential_workflow.rb
+++ b/lib/mars/rendering/graph/sequential_workflow.rb
@@ -20,19 +20,30 @@ def to_graph(builder, parent_id: nil, value: nil)
 
         def build_steps_graph(builder, parent_id, value)
           sink_nodes = []
+          extra_parents = []
 
           steps.each do |step|
             sink_nodes = step.to_graph(builder, parent_id: parent_id, value: value)
-            value = nil # We don't want to pass the value to subsequent steps
-            parent_id = step.node_id
+            extra_parents.each { |ep| builder.add_edge(ep, step.node_id) }
 
-            builder.add_node_to_subgraph(node_id, step.node_id)
+            value = nil
+            parent_id, extra_parents = process_sink_nodes(sink_nodes, step)
 
-            sink_nodes.each { |sink_node| builder.add_node_to_subgraph(node_id, sink_node) }
+            add_to_subgraph(builder, step, sink_nodes)
           end
 
           [parent_id, value, sink_nodes]
         end
+
+        def process_sink_nodes(sink_nodes, step)
+          unique_sinks = sink_nodes.uniq
+          [unique_sinks.first || step.node_id, unique_sinks.drop(1)]
+        end
+
+        def add_to_subgraph(builder, step, sink_nodes)
+          builder.add_node_to_subgraph(node_id, step.node_id)
+          sink_nodes.each { |sink_node| builder.add_node_to_subgraph(node_id, sink_node) }
+        end
       end
     end
   end