Resolve relative host paths in volume mount specs

.gitignore

@@ -0,0 +1 @@
+.agents/

internal/config.go

@@ -3,6 +3,7 @@ package internal
 import (
 	"fmt"
 	"os/exec"
+	"path/filepath"
 	goruntime "runtime"
 	"strings"
 	"time"
@@ -68,6 +69,9 @@ func ParseConfig(args []string, environment []string, startDir string) (Config,
 	// Build volumes with defaults (runtime-aware)
 	volumes := buildVolumes(cfg.Volumes, rt)
 
+	// Resolve relative host paths in volumes to absolute paths
+	volumes = resolveVolumePaths(volumes, startDir)
+
 	return Config{
 		Runtime:        rt,
 		ImageName:      ImageName(cfg.Image),
@@ -119,6 +123,28 @@ func buildVolumes(configVolumes []string, rt string) []string {
 	}
 }
 
+// resolveVolumePaths resolves relative host paths in volume mount specs to absolute paths.
+// Volume specs have the format [host-path:]container-path[:options].
+// Host paths starting with "." are treated as relative and resolved against baseDir.
+// Named volumes (no leading "/" or ".") and container-only specs are left unchanged.
+func resolveVolumePaths(volumes []string, baseDir string) []string {
+	resolved := make([]string, len(volumes))
+	for i, volume := range volumes {
+		hostPath, rest, hasColon := strings.Cut(volume, ":")
+		if !hasColon || !strings.HasPrefix(hostPath, ".") {
+			resolved[i] = volume
+			continue
+		}
+		absPath, err := filepath.Abs(filepath.Join(baseDir, hostPath))
+		if err != nil {
+			resolved[i] = volume
+			continue
+		}
+		resolved[i] = absPath + ":" + rest
+	}
+	return resolved
+}
+
 // buildEnvironment constructs the environment variable list with runtime-aware defaults
 func buildEnvironment(environment []string, configEnv map[string]string, rt string) []string {
 	lookup := make(map[string]string)

internal/config_test.go

@@ -1,6 +1,7 @@
 package internal_test
 
 import (
+	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -82,6 +83,59 @@ func TestConfig(t *testing.T) {
 			}, config.Volumes)
 		})
 
+		t.Run("with relative --volume host path", func(t *testing.T) {
+			dir := t.TempDir()
+			args := []string{
+				"--runtime", "apple",
+				"--volume", "./relative/path:/container/path",
+				"some-program",
+			}
+			env := []string{
+				"TERM=some-term",
+			}
+
+			config, err := internal.ParseConfig(args, env, dir)
+			require.NoError(t, err)
+			require.Equal(t, []string{
+				filepath.Join(dir, "relative/path") + ":/container/path",
+			}, config.Volumes)
+		})
+
+		t.Run("with relative --volume host path and options", func(t *testing.T) {
+			dir := t.TempDir()
+			args := []string{
+				"--runtime", "apple",
+				"--volume", "./data:/container/data:ro",
+				"some-program",
+			}
+			env := []string{
+				"TERM=some-term",
+			}
+
+			config, err := internal.ParseConfig(args, env, dir)
+			require.NoError(t, err)
+			require.Equal(t, []string{
+				filepath.Join(dir, "data") + ":/container/data:ro",
+			}, config.Volumes)
+		})
+
+		t.Run("with named volume is not resolved", func(t *testing.T) {
+			args := []string{
+				"--runtime", "apple",
+				"--volume", "myvolume:/container/path",
+				"some-program",
+			}
+			env := []string{
+				"TERM=some-term",
+			}
+
+			config, err := internal.ParseConfig(args, env, ".")
+			require.NoError(t, err)
+			require.Equal(t, []string{
+				"myvolume:/container/path",
+			}, config.Volumes)
+		})
+
 		t.Run("with multiple --volume flags", func(t *testing.T) {
 			args := []string{
 				"--runtime", "apple",