Fix model routing to read the agent-job task prompt

go.mod

@@ -39,6 +39,7 @@ require (
 
 require (
 	github.com/rhysd/actionlint v1.7.12
+	go.yaml.in/yaml/v3 v3.0.5
 	golang.org/x/net v0.59.0
 )
 
@@ -112,7 +113,6 @@ require (
 	go.opentelemetry.io/otel/metric v1.45.0 // indirect
 	go.opentelemetry.io/otel/trace v1.45.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
-	go.yaml.in/yaml/v3 v3.0.5 // indirect
 	go.yaml.in/yaml/v4 v4.0.0-rc.6 // indirect
 	golang.org/x/exp v0.0.0-20240909161429-701f63a606c0 // indirect
 	golang.org/x/oauth2 v0.36.0 // indirect

pkg/constants/constants.go

@@ -577,6 +577,12 @@ const AwPromptsFileExpr = GhAwRootDir + "/aw-prompts/prompt.txt"
 // AwPromptsFileShell is the runtime prompt file path in shell env-var form for host-side paths.
 const AwPromptsFileShell = GhAwRootDirShell + "/aw-prompts/prompt.txt"
 
+// AwPromptsUserFile is the runtime task-only prompt file path.
+const AwPromptsUserFile = TmpGhAwDir + "/aw-prompts/user.txt"
+
+// AwPromptsUserFileExpr is the host-side task-only prompt path in GitHub Actions expression form.
+const AwPromptsUserFileExpr = GhAwRootDir + "/aw-prompts/user.txt"
+
 // TmpMcpConfigDir is the mcp-config directory in the /tmp/gh-aw tree.
 // Engines that require a writable MCP config directory (e.g. Codex) use this path.
 const TmpMcpConfigDir = TmpGhAwDir + "/mcp-config"

pkg/workflow/model_routing.go

@@ -282,9 +282,12 @@ func generateModelRoutingConversationStep(yaml *strings.Builder, data *WorkflowD
 	if !isModelRoutingEnabled(data) {
 		return
 	}
+	promptFilePath := constants.AwPromptsUserFile
+	fallbackFilePath := constants.AwPromptsFile
 	yaml.WriteString("      - name: Prepare model-routing conversation\n")
 	yaml.WriteString("        env:\n")
-	yaml.WriteString("          GH_AW_ROUTING_PROMPT: " + constants.AwPromptsFileExpr + "\n")
+	yaml.WriteString("          GH_AW_ROUTING_PROMPT: " + promptFilePath + "\n")
+	yaml.WriteString("          GH_AW_ROUTING_PROMPT_FALLBACK: " + fallbackFilePath + "\n")
 	yaml.WriteString("          GH_AW_ROUTING_CONVERSATION_FILE: " + modelRoutingConversationFile + "\n")
-	yaml.WriteString("        run: node -e \"const fs=require('node:fs'); const path=require('node:path'); const prompt=fs.readFileSync(process.env.GH_AW_ROUTING_PROMPT,'utf8'); if (!prompt.trim()) throw new Error('Rendered workflow prompt is empty; cannot route this task'); const destination=process.env.GH_AW_ROUTING_CONVERSATION_FILE; fs.mkdirSync(path.dirname(destination),{recursive:true,mode:0o700}); fs.writeFileSync(destination,JSON.stringify([{role:'user',parts:[{text:prompt}]}]),{mode:0o600});\"\n")
+	yaml.WriteString("        run: node -e \"const fs=require('node:fs'); const path=require('node:path'); const readPrompt=file=>{try{return fs.readFileSync(file,'utf8');}catch(error){if(error.code==='ENOENT')return '';throw error;}}; let prompt=readPrompt(process.env.GH_AW_ROUTING_PROMPT); if (!prompt.trim()) prompt=readPrompt(process.env.GH_AW_ROUTING_PROMPT_FALLBACK); if (!prompt.trim()) throw new Error('Rendered workflow prompt is empty; cannot route this task'); const destination=process.env.GH_AW_ROUTING_CONVERSATION_FILE; fs.mkdirSync(path.dirname(destination),{recursive:true,mode:0o700}); fs.writeFileSync(destination,JSON.stringify([{role:'user',parts:[{text:prompt}]}]),{mode:0o600});\"\n")
 }

pkg/workflow/model_routing_test.go

@@ -2,10 +2,15 @@ package workflow
 
 import (
 	"encoding/json"
+	"os"
+	"os/exec"
+	"path/filepath"
 	"strings"
 	"testing"
 
+	"github.com/github/gh-aw/pkg/constants"
 	"github.com/stretchr/testify/require"
+	yamlv3 "go.yaml.in/yaml/v3"
 )
 
 func TestBuildAWFConfigJSON_ModelRouting(t *testing.T) {
@@ -63,15 +68,132 @@ func TestValidateModelRoutingRequiresMinimumAWFVersion(t *testing.T) {
 }
 
 func TestGenerateModelRoutingConversationStep(t *testing.T) {
+	for _, tc := range []struct {
+		name     string
+		topology RunnerTopology
+		prompt   string
+		fallback string
+	}{
+		{"hosted", "", constants.AwPromptsUserFile, constants.AwPromptsFile},
+		{"arc-dind", RunnerTopologyArcDind, constants.AwPromptsUserFile, constants.AwPromptsFile},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			var output strings.Builder
+			generateModelRoutingConversationStep(&output, &WorkflowData{
+				EngineConfig: &EngineConfig{ModelRouting: &CopilotModelRoutingConfig{}},
+				RunnerConfig: &RunnerConfig{Topology: tc.topology},
+			})
+
+			require.Contains(t, output.String(), "Prepare model-routing conversation")
+			require.Contains(t, output.String(), "GH_AW_ROUTING_PROMPT: "+tc.prompt+"\n")
+			require.Contains(t, output.String(), "GH_AW_ROUTING_PROMPT_FALLBACK: "+tc.fallback+"\n")
+			require.Contains(t, output.String(), modelRoutingConversationFile)
+			require.Contains(t, output.String(), "role:'user',parts:[{text:prompt}]")
+			require.NotContains(t, output.String(), "${{ runner.temp }}")
+			require.NotContains(t, output.String(), "${RUNNER_TEMP}")
+
+			source := `---
+on: workflow_dispatch
+strict: false
+engine:
+  id: copilot
+  model-routing:
+    goal: cost
+    mode: balanced
+    allowed-models: [gpt-5.4-mini]
+network:
+  allowed: [defaults]
+`
+			if tc.topology != "" {
+				source += "runner:\n  topology: " + string(tc.topology) + "\n"
+				source += "sandbox:\n  agent:\n    images:\n      build-tools: registry.example.com/build-tools:v0.28.4@sha256:" + strings.Repeat("1", 64) + "\n"
+			}
+			source += "---\nSay hello.\n"
+			dir := t.TempDir()
+			workflowPath := filepath.Join(dir, "routed.md")
+			require.NoError(t, os.WriteFile(workflowPath, []byte(source), 0o600))
+			require.NoError(t, NewCompiler().CompileWorkflow(workflowPath))
+			compiled, err := os.ReadFile(filepath.Join(dir, "routed.lock.yml"))
+			require.NoError(t, err)
+			compiledYAML := string(compiled)
+			require.Contains(t, compiledYAML, output.String())
+			if tc.topology == RunnerTopologyArcDind {
+				routingStepIndex := strings.Index(compiledYAML, "- name: Prepare model-routing conversation")
+				promptStagingIndex := strings.Index(compiledYAML, "cp -a /tmp/gh-aw/aw-prompts")
+				require.NotEqual(t, -1, routingStepIndex)
+				require.NotEqual(t, -1, promptStagingIndex)
+				require.Greater(t, promptStagingIndex, routingStepIndex)
+			}
+		})
+	}
+}
+
+func TestModelRoutingConversationPromptFallback(t *testing.T) {
 	var yaml strings.Builder
 	generateModelRoutingConversationStep(&yaml, &WorkflowData{
 		EngineConfig: &EngineConfig{ModelRouting: &CopilotModelRoutingConfig{}},
 	})
 
-	require.Contains(t, yaml.String(), "Prepare model-routing conversation")
-	require.Contains(t, yaml.String(), "GH_AW_ROUTING_PROMPT")
-	require.Contains(t, yaml.String(), modelRoutingConversationFile)
-	require.Contains(t, yaml.String(), "role:'user',parts:[{text:prompt}]")
+	var steps []struct {
+		Run string
+	}
+	require.NoError(t, yamlv3.Unmarshal([]byte(yaml.String()), &steps))
+	require.Len(t, steps, 1)
+
+	task := "  Task with \"quotes\", $variables, and a newline\n"
+	fullPrompt := "System instructions\nFull workflow prompt"
+	for _, tc := range []struct {
+		name     string
+		task     *string
+		fallback *string
+		want     string
+	}{
+		{"task only", &task, &fullPrompt, task},
+		{"task without fallback", &task, nil, task},
+		{"missing task", nil, &fullPrompt, fullPrompt},
+		{"blank task", new(" \n\t"), &fullPrompt, fullPrompt},
+		{"empty task", new(""), &fullPrompt, fullPrompt},
+		{"both missing", nil, nil, ""},
+		{"both blank", new("\n"), new(" \t"), ""},
+		{"blank task missing fallback", new(" "), nil, ""},
+		{"missing task blank fallback", nil, new("\n"), ""},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			dir := t.TempDir()
+			taskPath := filepath.Join(dir, "user.txt")
+			fallbackPath := filepath.Join(dir, "prompt.txt")
+			conversationPath := filepath.Join(dir, "output", "routing-conversation.json")
+			for file, text := range map[string]*string{taskPath: tc.task, fallbackPath: tc.fallback} {
+				if text != nil {
+					require.NoError(t, os.WriteFile(file, []byte(*text), 0o600))
+				}
+			}
+			cmd := exec.Command("bash", "-c", steps[0].Run)
+			cmd.Env = append(os.Environ(),
+				"GH_AW_ROUTING_PROMPT="+taskPath,
+				"GH_AW_ROUTING_PROMPT_FALLBACK="+fallbackPath,
+				"GH_AW_ROUTING_CONVERSATION_FILE="+conversationPath,
+			)
+			output, err := cmd.CombinedOutput()
+			if tc.want == "" {
+				require.Error(t, err)
+				require.Contains(t, string(output), "Rendered workflow prompt is empty; cannot route this task")
+				require.NoFileExists(t, conversationPath)
+				return
+			}
+			require.NoError(t, err, string(output))
+			conversation, err := os.ReadFile(conversationPath)
+			require.NoError(t, err)
+			expected, err := json.Marshal([]any{map[string]any{
+				"role": "user", "parts": []any{map[string]any{"text": tc.want}},
+			}})
+			require.NoError(t, err)
+			require.JSONEq(t, string(expected), string(conversation))
+			info, err := os.Stat(conversationPath)
+			require.NoError(t, err)
+			require.Equal(t, os.FileMode(0o600), info.Mode().Perm())
+		})
+	}
 }
 
 func TestExtractEngineConfig_ModelRouting(t *testing.T) {