Model routing: an omitted allowed-models means any model when merging imports

docs/src/content/docs/reference/frontmatter-full.md

@@ -2736,6 +2736,8 @@ engine:
     # agent only. This is not a request policy; put patterns such as gpt-* in
     # models.allowed or models.blocked. When omitted, the router chooses from the
     # models that policy allows (Claude and Codex only from their own model family).
+    # Lists from imported workflows using the same engine are combined, but if the
+    # main workflow or any import omits allowed-models, the router has no shortlist.
     # GitHub Actions expressions are allowed only when neither models.allowed nor
     # models.blocked is set.
     # (optional)
@@ -21336,6 +21338,8 @@ safe-outputs:
         # agent only. This is not a request policy; put patterns such as gpt-* in
         # models.allowed or models.blocked. When omitted, the router chooses from the
         # models that policy allows (Claude and Codex only from their own model family).
+        # Lists from imported workflows using the same engine are combined, but if the
+        # main workflow or any import omits allowed-models, the router has no shortlist.
         # GitHub Actions expressions are allowed only when neither models.allowed nor
         # models.blocked is set.
         # (optional)

docs/src/content/docs/reference/model-routing.md

@@ -185,7 +185,7 @@ imports:
 Summarize the open pull requests.
 ```
 
-The importing workflow must either omit `engine` or use its object form, such as `engine: { id: copilot }`. If it also enables routing for the same engine, its `goal` and `mode` apply, and the imported `allowed-models` entries are added to its own. If it enables routing without `allowed-models`, the router chooses from only the imported entries.
+The importing workflow must either omit `engine` or use its object form, such as `engine: { id: copilot }`. If it also enables routing for the same engine, its `goal` and `mode` apply. If the importing workflow or any import omits `allowed-models`, the router has no shortlist. Otherwise, the `allowed-models` lists are combined.
 
 ### Keeping up with new models
 

pkg/parser/schemas/main_workflow_schema.json

@@ -15225,7 +15225,7 @@
                       }
                     ]
                   },
-                  "description": "Optional exact Copilot model names that narrow the router's choice for the main agent only. This is not a request policy; put patterns such as gpt-* in models.allowed or models.blocked. When omitted, the router chooses from the models that policy allows (Claude and Codex only from their own model family). GitHub Actions expressions are allowed only when neither models.allowed nor models.blocked is set."
+                  "description": "Optional exact Copilot model names that narrow the router's choice for the main agent only. This is not a request policy; put patterns such as gpt-* in models.allowed or models.blocked. When omitted, the router chooses from the models that policy allows (Claude and Codex only from their own model family). Lists from imported workflows using the same engine are combined, but if the main workflow or any import omits allowed-models, the router has no shortlist. GitHub Actions expressions are allowed only when neither models.allowed nor models.blocked is set."
                 }
               }
             },

pkg/workflow/compiler_orchestrator_engine.go

@@ -383,6 +383,11 @@ func (c *Compiler) mergeImportedModelRoutingConfigs(engineConfig *EngineConfig,
 			engineConfig.ModelRouting = &routing
 			continue
 		}
+		// An omitted allowed-models list means "any model", so it wins over any list.
+		if engineConfig.ModelRouting.AllowedModels == nil || importedConfig.ModelRouting.AllowedModels == nil {
+			engineConfig.ModelRouting.AllowedModels = nil
+			continue
+		}
 		seen := make(map[string]struct{}, len(engineConfig.ModelRouting.AllowedModels))
 		for _, model := range engineConfig.ModelRouting.AllowedModels {
 			seen[model] = struct{}{}

pkg/workflow/model_routing_subagents_test.go

@@ -258,3 +258,98 @@ sandbox:
 		"github-copilot/claude-haiku-4.5",
 	}, config["apiProxy"].(map[string]any)["routing"].(map[string]any)["candidateModels"])
 }
+
+func TestImportedWorkflowModelRoutingOmittedAllowedModelsMeansAnyModel(t *testing.T) {
+	routingImport := func(allowedModels string) string {
+		content := "---\nengine:\n  id: copilot\n  model-routing:\n    goal: cost-speed\n    mode: robust\n"
+		if allowedModels != "" {
+			content += "    allowed-models: " + allowedModels + "\n"
+		}
+		return content + "---\n# Shared routing\n"
+	}
+	tests := []struct {
+		name          string
+		mainRouting   string
+		imports       map[string]string
+		importOrder   []string
+		expectedModel []string
+	}{
+		{
+			name:          "main omits allowed-models, import lists models",
+			mainRouting:   "  model-routing:\n    goal: cost\n    mode: economy\n",
+			imports:       map[string]string{"routing.md": routingImport("[claude-sonnet-5]")},
+			importOrder:   []string{"routing.md"},
+			expectedModel: nil,
+		},
+		{
+			name:          "main lists models, import omits allowed-models",
+			mainRouting:   "  model-routing:\n    goal: cost\n    mode: economy\n    allowed-models: [gpt-6-sol]\n",
+			imports:       map[string]string{"routing.md": routingImport("")},
+			importOrder:   []string{"routing.md"},
+			expectedModel: nil,
+		},
+		{
+			name:          "main without routing, omitted import before listed import",
+			imports:       map[string]string{"omitted.md": routingImport(""), "listed.md": routingImport("[claude-sonnet-5]")},
+			importOrder:   []string{"omitted.md", "listed.md"},
+			expectedModel: nil,
+		},
+		{
+			name:          "main without routing, listed import before omitted import",
+			imports:       map[string]string{"omitted.md": routingImport(""), "listed.md": routingImport("[claude-sonnet-5]")},
+			importOrder:   []string{"listed.md", "omitted.md"},
+			expectedModel: nil,
+		},
+		{
+			name:          "main without routing, import lists models",
+			imports:       map[string]string{"routing.md": routingImport("[claude-sonnet-5]")},
+			importOrder:   []string{"routing.md"},
+			expectedModel: []string{"claude-sonnet-5"},
+		},
+		{
+			name:          "main and import list models",
+			mainRouting:   "  model-routing:\n    goal: cost\n    mode: economy\n    allowed-models: [gpt-6-sol]\n",
+			imports:       map[string]string{"routing.md": routingImport("[claude-sonnet-5, gpt-6-sol]")},
+			importOrder:   []string{"routing.md"},
+			expectedModel: []string{"gpt-6-sol", "claude-sonnet-5"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			dir := t.TempDir()
+			for name, content := range tt.imports {
+				require.NoError(t, os.WriteFile(filepath.Join(dir, name), []byte(content), 0600))
+			}
+			var importsYAML strings.Builder
+			for _, name := range tt.importOrder {
+				importsYAML.WriteString("  - " + name + "\n")
+			}
+			source := filepath.Join(dir, "routed.md")
+			require.NoError(t, os.WriteFile(source, []byte("---\non: workflow_dispatch\npermissions:\n  contents: read\n  copilot-requests: write\nstrict: false\nimports:\n"+
+				importsYAML.String()+"engine:\n  id: copilot\n"+tt.mainRouting+"---\n# Routed workflow\n"), 0600))
+
+			data, err := NewCompiler().ParseWorkflowFile(source)
+			require.NoError(t, err)
+			require.NotNil(t, data.EngineConfig.ModelRouting)
+			require.Equal(t, tt.expectedModel, data.EngineConfig.ModelRouting.AllowedModels)
+			setRoutingCandidateModelsProxyImage(data, "0.28.33")
+
+			configJSON, err := BuildAWFConfigJSON(AWFCommandConfig{
+				EngineName: "copilot", AllowedDomains: "github.com", WorkflowData: data,
+			})
+			require.NoError(t, err)
+			var config map[string]any
+			require.NoError(t, json.Unmarshal([]byte(configJSON), &config))
+			routing := config["apiProxy"].(map[string]any)["routing"].(map[string]any)
+			if tt.expectedModel == nil {
+				require.NotContains(t, routing, "candidateModels")
+				return
+			}
+			expected := make([]any, 0, len(tt.expectedModel))
+			for _, model := range tt.expectedModel {
+				expected = append(expected, "github-copilot/"+model)
+			}
+			require.Equal(t, expected, routing["candidateModels"])
+		})
+	}
+}