Fix Copilot SDK crashes in Cloud Hypervisor

pkg/workflow/cloud_hypervisor_test.go

@@ -205,8 +205,11 @@ func TestCloudHypervisorAWFConfigJSON(t *testing.T) {
 			NetworkPermissions: &NetworkPermissions{
 				Firewall: &FirewallConfig{Enabled: true},
 			},
-			Tools:         map[string]any{"github": map[string]any{"mode": "gh-proxy"}},
-			SandboxConfig: &SandboxConfig{Agent: &AgentSandboxConfig{ID: "awf", Runtime: AgentRuntimeCloudHypervisor}},
+			Tools: map[string]any{"github": map[string]any{"mode": "gh-proxy"}},
+			SandboxConfig: applySandboxDefaults(
+				&SandboxConfig{Agent: &AgentSandboxConfig{ID: "awf", Runtime: AgentRuntimeCloudHypervisor}},
+				&EngineConfig{ID: "copilot"},
+			),
 		},
 	}
 
@@ -218,6 +221,7 @@ func TestCloudHypervisorAWFConfigJSON(t *testing.T) {
 	assert.Contains(t, jsonStr, `"topologyAttach":["awmg-mcpg"]`)
 	assert.NotContains(t, jsonStr, "awmg-cli-proxy")
 	assert.Contains(t, jsonStr, `"agentTimeout":60`)
+	assert.Contains(t, jsonStr, `"allowWrite":["/tmp/gh-aw/agent","/tmp/gh-aw/sandbox/agent/logs","/workspace","/workspace/.awf-home"]`)
 }
 
 func TestCloudHypervisorValidationArcDindIncompatible(t *testing.T) {

pkg/workflow/sandbox.go

@@ -16,6 +16,7 @@ package workflow
 import (
 	"slices"
 
+	"github.com/github/gh-aw/pkg/constants"
 	"github.com/github/gh-aw/pkg/logger"
 	"github.com/github/gh-aw/pkg/sliceutil"
 )
@@ -30,7 +31,10 @@ const (
 	SandboxTypeDefault SandboxType = "default" // Alias for AWF (backward compat)
 )
 
-const defaultAgentWorkspaceWritePath = "/tmp/gh-aw/agent"
+const (
+	defaultAgentWorkspaceWritePath = "/tmp/gh-aw/agent"
+	defaultAgentLogsWritePath      = "/tmp/gh-aw/sandbox/agent/logs"
+)
 
 // SandboxConfig represents the top-level sandbox configuration from front matter
 // New format: { agent: "awf"|"srt"|{type, config}, mcp: {port, command, ...} }
@@ -246,15 +250,15 @@ func applySandboxDefaults(sandboxConfig *SandboxConfig, engineConfig *EngineConf
 				Type: SandboxTypeAWF,
 			},
 		}
-		ensureDefaultAgentWritePath(sandboxConfig)
+		ensureDefaultAgentWritePath(sandboxConfig, engineConfig)
 		return sandboxConfig
 	}
 
 	// If sandbox config exists with legacy Type field set, don't override with awf default
 	// The legacy Type field indicates explicit sandbox configuration
 	if sandboxConfig.Type != "" {
 		sandboxLog.Printf("Sandbox config uses legacy Type field: %s, preserving it", sandboxConfig.Type)
-		ensureDefaultAgentWritePath(sandboxConfig)
+		ensureDefaultAgentWritePath(sandboxConfig, engineConfig)
 		return sandboxConfig
 	}
 
@@ -264,7 +268,7 @@ func applySandboxDefaults(sandboxConfig *SandboxConfig, engineConfig *EngineConf
 		sandboxConfig.Agent = &AgentSandboxConfig{
 			Type: SandboxTypeAWF,
 		}
-		ensureDefaultAgentWritePath(sandboxConfig)
+		ensureDefaultAgentWritePath(sandboxConfig, engineConfig)
 		return sandboxConfig
 	}
 
@@ -279,12 +283,12 @@ func applySandboxDefaults(sandboxConfig *SandboxConfig, engineConfig *EngineConf
 		sandboxConfig.Agent.Type = SandboxTypeAWF
 	}
 
-	ensureDefaultAgentWritePath(sandboxConfig)
+	ensureDefaultAgentWritePath(sandboxConfig, engineConfig)
 	return sandboxConfig
 }
 
-// cloudHypervisorWorkspaceWritePath and cloudHypervisorAwfHomeWritePath are the additional
-// filesystem.allowWrite entries seeded for the Cloud Hypervisor runtime.
+// Cloud Hypervisor requires explicit filesystem.allowWrite entries for compiler-managed
+// output paths as well as the workspace.
 //
 // Under Cloud Hypervisor, /workspace and /tmp/gh-aw are separate virtiofs exports, and the
 // AWF planner narrows each export independently based on the allowWrite entries that fall
@@ -306,7 +310,7 @@ const cloudHypervisorAwfHomeWritePath = "/workspace/.awf-home"
 // container fails to start ("make mountpoint \"/tmp/awf-init\": read-only file system").
 // Seeding a default there would therefore break every compose-runtime workflow, so
 // filesystem.allowWrite stays opt-in for those runtimes.
-func ensureDefaultAgentWritePath(sandboxConfig *SandboxConfig) {
+func ensureDefaultAgentWritePath(sandboxConfig *SandboxConfig, engineConfig *EngineConfig) {
 	if sandboxConfig == nil || sandboxConfig.Agent == nil {
 		return
 	}
@@ -320,6 +324,9 @@ func ensureDefaultAgentWritePath(sandboxConfig *SandboxConfig) {
 		sandboxConfig.Agent.Config.Filesystem = &SRTFilesystemConfig{}
 	}
 	addAllowWritePathIfMissing(sandboxConfig.Agent.Config.Filesystem, defaultAgentWorkspaceWritePath)
+	if engineConfig != nil && engineConfig.ID == string(constants.CopilotEngine) {
+		addAllowWritePathIfMissing(sandboxConfig.Agent.Config.Filesystem, defaultAgentLogsWritePath)
+	}
 	addAllowWritePathIfMissing(sandboxConfig.Agent.Config.Filesystem, cloudHypervisorWorkspaceWritePath)
 	addAllowWritePathIfMissing(sandboxConfig.Agent.Config.Filesystem, cloudHypervisorAwfHomeWritePath)
 }

pkg/workflow/sandbox_test.go

@@ -142,6 +142,7 @@ func TestApplySandboxDefaults(t *testing.T) {
 		expected               *SandboxConfig
 		expectDefaultWritePath bool
 		expectedAllowWrite     []string
+		unexpectedAllowWrite   []string
 	}{
 		{
 			name:                   "nil config creates default with AWF",
@@ -245,7 +246,7 @@ func TestApplySandboxDefaults(t *testing.T) {
 			// Cloud Hypervisor narrows the /workspace and /tmp/gh-aw exports independently,
 			// so the default write path alone would leave /workspace (and the CH-managed
 			// HOME under it) read-only. See ensureDefaultAgentWritePath.
-			name: "cloud-hypervisor runtime seeds agent, workspace and awf-home write paths",
+			name: "cloud-hypervisor runtime seeds agent, logs, workspace and awf-home write paths",
 			config: &SandboxConfig{
 				Agent: &AgentSandboxConfig{
 					Type:    SandboxTypeAWF,
@@ -254,7 +255,25 @@ func TestApplySandboxDefaults(t *testing.T) {
 			},
 			engine:                 &EngineConfig{ID: "copilot"},
 			expectDefaultWritePath: true,
+			expectedAllowWrite:     []string{defaultAgentWorkspaceWritePath, defaultAgentLogsWritePath, cloudHypervisorWorkspaceWritePath, cloudHypervisorAwfHomeWritePath},
+			expected: &SandboxConfig{
+				Agent: &AgentSandboxConfig{
+					Type: SandboxTypeAWF,
+				},
+			},
+		},
+		{
+			name: "cloud-hypervisor runtime does not grant Copilot logs path to other engines",
+			config: &SandboxConfig{
+				Agent: &AgentSandboxConfig{
+					Type:    SandboxTypeAWF,
+					Runtime: AgentRuntimeCloudHypervisor,
+				},
+			},
+			engine:                 &EngineConfig{ID: "claude"},
+			expectDefaultWritePath: true,
 			expectedAllowWrite:     []string{defaultAgentWorkspaceWritePath, cloudHypervisorWorkspaceWritePath, cloudHypervisorAwfHomeWritePath},
+			unexpectedAllowWrite:   []string{defaultAgentLogsWritePath},
 			expected: &SandboxConfig{
 				Agent: &AgentSandboxConfig{
 					Type: SandboxTypeAWF,
@@ -285,6 +304,11 @@ func TestApplySandboxDefaults(t *testing.T) {
 				require.NotNil(t, result.Agent.Config.Filesystem)
 				assert.Contains(t, result.Agent.Config.Filesystem.AllowWrite, expectedPath)
 			}
+			for _, unexpectedPath := range tt.unexpectedAllowWrite {
+				require.NotNil(t, result.Agent.Config)
+				require.NotNil(t, result.Agent.Config.Filesystem)
+				assert.NotContains(t, result.Agent.Config.Filesystem.AllowWrite, unexpectedPath)
+			}
 		})
 	}
 }