Generate execution plans on-the-fly for plan visualization

Instead of only showing cached plans, now attempts to generate
a plan from the recipe if no cached plan is found. This works
for recipe-based runs even if they were started via the legacy
execute_dag path.

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

server.py

@@ -1324,10 +1324,43 @@ async def run_plan_visualization(run_id: str, request: Request):
         except (json.JSONDecodeError, IOError):
             continue
 
+    # If no cached plan, try to generate one from the recipe
+    if not plan_data:
+        recipe_name = run.recipe.replace("recipe:", "") if run.recipe.startswith("recipe:") else run.recipe
+        recipe_status = None
+        for recipe in list_all_recipes():
+            if recipe.name == recipe_name:
+                recipe_status = recipe
+                break
+
+        if recipe_status:
+            recipe_path = cache_manager.get_by_content_hash(recipe_status.recipe_id)
+            if recipe_path and recipe_path.exists():
+                try:
+                    recipe_yaml = recipe_path.read_text()
+                    # Build input_hashes mapping from run inputs
+                    input_hashes = {}
+                    for i, var_input in enumerate(recipe_status.variable_inputs):
+                        if i < len(run.inputs):
+                            input_hashes[var_input.node_id] = run.inputs[i]
+
+                    # Try to generate plan using the orchestrate module
+                    try:
+                        from tasks.orchestrate import generate_plan as gen_plan_task
+                        # Call synchronously (it's fast for just planning)
+                        plan_result = gen_plan_task(recipe_yaml, input_hashes)
+                        if plan_result and plan_result.get("status") == "planned":
+                            plan_data = plan_result
+                    except ImportError:
+                        pass
+                except Exception as e:
+                    logger.warning(f"Failed to generate plan for run {run_id}: {e}")
+
     # Build sub-navigation tabs
     tabs_html = render_run_sub_tabs(run_id, active="plan")
 
     if not plan_data:
+        # Show a simpler visualization based on the run's recipe structure
         content = f'''
         <a href="/runs" class="inline-flex items-center text-blue-400 hover:text-blue-300 mb-6">
             <svg class="w-4 h-4 mr-1" fill="none" stroke="currentColor" viewBox="0 0 24 24">
@@ -1340,8 +1373,8 @@ async def run_plan_visualization(run_id: str, request: Request):
 
         <div class="bg-dark-700 rounded-lg p-6">
             <h2 class="text-xl font-bold text-white mb-4">Execution Plan</h2>
-            <p class="text-gray-400">No execution plan available for this run.</p>
-            <p class="text-gray-500 text-sm mt-2">Plans are generated when using recipe-based runs with the v2 API.</p>
+            <p class="text-gray-400">Could not generate execution plan for this run.</p>
+            <p class="text-gray-500 text-sm mt-2">This may be a legacy effect-based run without a recipe, or the recipe is no longer available.</p>
         </div>
         '''
         return HTMLResponse(render_page_with_cytoscape(f"Plan: {run_id[:16]}...", content, ctx.actor_id, active_tab="runs"))