Downgrade read-only maintenance workflows from Sonnet to Haiku

.github/workflows/impeccable-skills-reviewer.md

@@ -18,7 +18,7 @@ sandbox:
 
 engine:
   id: copilot
-  model: claude-sonnet-4.6
+  model: claude-haiku-4.5
   max-continuations: 6
 imports:
   - uses: shared/pr-review-base.md

.github/workflows/mattpocock-skills-reviewer.md

@@ -20,7 +20,7 @@ sandbox:
 
 engine:
   id: copilot
-  model: claude-sonnet-4.6
+  model: claude-haiku-4.5
   max-continuations: 6
 imports:
   - uses: shared/pr-review-base.md

.github/workflows/pr-description-caveman.md

@@ -15,6 +15,10 @@ sandbox:
   agent:
     sudo: false
 
+engine:
+  id: copilot
+  model: claude-haiku-4.5
+
 strict: true
 tools:
   github:
@@ -170,7 +174,7 @@ Do not read additional files or invoke shell tools. The chunk content is provide
 ## agent: `pr-description-synthesizer`
 ---
 description: Combines per-chunk analysis results and diff metadata into a final structured PR description optimised for agentic analysis.
-model: large
+model: claude-haiku-4.5
 ---
 
 You receive:

pkg/cli/read_only_maintenance_workflow_models_contract_test.go

@@ -0,0 +1,48 @@
+//go:build !integration
+
+package cli
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/github/gh-aw/pkg/gitutil"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestReadOnlyMaintenanceWorkflowsUseHaikuModels(t *testing.T) {
+	repoRoot, err := gitutil.FindGitRoot()
+	if err != nil {
+		t.Skipf("Skipping test: not in a git repository: %v", err)
+	}
+
+	t.Run("pr-description-updater", func(t *testing.T) {
+		workflowPath := filepath.Join(repoRoot, ".github", "workflows", "pr-description-caveman.md")
+		content, err := os.ReadFile(workflowPath)
+		require.NoError(t, err, "Should read pr-description-caveman workflow")
+
+		text := string(content)
+		assert.Contains(t, text, "engine:\n  id: copilot", "Workflow should declare a top-level Copilot engine block")
+		assert.Contains(t, text, "\n  model: claude-haiku-4.5\n", "Workflow should pin a cheaper Haiku top-level model")
+		assert.Contains(t, text, "## agent: `pr-description-synthesizer`", "Workflow should keep the dedicated synthesizer sub-agent")
+		assert.Contains(t, text, "## agent: `pr-description-synthesizer`\n---\ndescription: Combines per-chunk analysis results and diff metadata into a final structured PR description optimised for agentic analysis.\nmodel: claude-haiku-4.5", "Workflow synthesizer should use a cheaper Haiku model")
+		assert.NotContains(t, text, "model: large", "Workflow should no longer use the expensive large alias for PR description synthesis")
+	})
+
+	for _, workflowName := range []string{
+		"impeccable-skills-reviewer.md",
+		"mattpocock-skills-reviewer.md",
+	} {
+		t.Run(workflowName, func(t *testing.T) {
+			workflowPath := filepath.Join(repoRoot, ".github", "workflows", workflowName)
+			content, err := os.ReadFile(workflowPath)
+			require.NoError(t, err, "Should read %s workflow", workflowName)
+
+			text := string(content)
+			assert.Contains(t, text, "model: claude-haiku-4.5", "Read-only maintenance workflow should pin a cheaper Haiku model")
+			assert.NotContains(t, text, "model: claude-sonnet-4.6", "Read-only maintenance workflow should no longer use a Sonnet frontier model")
+		})
+	}
+}