fix: persist machine config.mounts (#59)

CHANGELOG.md

@@ -6,6 +6,17 @@ adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+## [0.4.1] - 2026-07-14
+
+### Fixed
+
+- Machine `config.mounts` is now persisted and echoed back. Previously
+  `MachineConfig` had no `mounts` field, so a create body's mounts were dropped
+  on unmarshal and `GET .../machines` returned `config.mounts: null` — making a
+  mounting machine look drifted on every reconcile (it never no-op'd). The field
+  now mirrors fly-go's `MachineMount` and round-trips through create → GET
+  (INTENTIUS/chant#868, #59).
+
 ## [0.4.0] - 2026-07-12
 
 ### Added
@@ -111,7 +122,9 @@ Fidelity and correctness pass from an adversarial audit against `superfly/fly-go
 - Distroless container image, GoReleaser configuration, mkdocs-material doc site,
   and CI.
 
-[Unreleased]: https://github.com/intentius/mudflaps/compare/v0.3.1...HEAD
+[Unreleased]: https://github.com/intentius/mudflaps/compare/v0.4.1...HEAD
+[0.4.1]: https://github.com/intentius/mudflaps/compare/v0.4.0...v0.4.1
+[0.4.0]: https://github.com/intentius/mudflaps/compare/v0.3.1...v0.4.0
 [0.3.1]: https://github.com/intentius/mudflaps/compare/v0.3.0...v0.3.1
 [0.3.0]: https://github.com/intentius/mudflaps/compare/v0.2.0...v0.3.0
 [0.2.0]: https://github.com/intentius/mudflaps/compare/v0.1.0...v0.2.0

internal/flaps/types.go

@@ -85,6 +85,22 @@ type MachineConfig struct {
 	Guest    *MachineGuest     `json:"guest,omitempty"`
 	Services []Service         `json:"services,omitempty"`
 	Restart  *Restart          `json:"restart,omitempty"`
+	Mounts   []MachineMount    `json:"mounts,omitempty"`
+}
+
+// MachineMount attaches a volume to a machine at a path. Field names mirror
+// fly-go's MachineMount so a create body round-trips through GET unchanged —
+// without this, mounts would be dropped on unmarshal and a mounting machine
+// would look drifted on every reconcile.
+type MachineMount struct {
+	Volume                 string `json:"volume,omitempty"`
+	Path                   string `json:"path,omitempty"`
+	Name                   string `json:"name,omitempty"`
+	Encrypted              bool   `json:"encrypted,omitempty"`
+	SizeGb                 int    `json:"size_gb,omitempty"`
+	SizeGbLimit            int    `json:"size_gb_limit,omitempty"`
+	AddSizeGb              int    `json:"add_size_gb,omitempty"`
+	ExtendThresholdPercent int    `json:"extend_threshold_percent,omitempty"`
 }
 
 // MachineGuest is the resource allocation for a machine.

internal/store/store.go

@@ -205,6 +205,11 @@ func cloneMachine(m *flaps.Machine) *flaps.Machine {
 			}
 			cfg.Services = svcs
 		}
+		if m.Config.Mounts != nil {
+			mounts := make([]flaps.MachineMount, len(m.Config.Mounts))
+			copy(mounts, m.Config.Mounts)
+			cfg.Mounts = mounts
+		}
 		c.Config = &cfg
 	}
 	if m.ImageRef != nil {

internal/store/store_test.go

@@ -169,3 +169,35 @@ func TestClonedMachinePortsAreIsolated(t *testing.T) {
 		t.Fatalf("clone aliased stored handlers: got %q, want tls", got)
 	}
 }
+
+func TestMachineMountsRoundTrip(t *testing.T) {
+	s := New()
+	if _, err := s.CreateApp(flaps.App{Name: "demo"}); err != nil {
+		t.Fatalf("CreateApp: %v", err)
+	}
+	m := flaps.Machine{
+		ID:     "m1",
+		State:  flaps.StateCreating,
+		Config: &flaps.MachineConfig{Image: "nginx", Mounts: []flaps.MachineMount{{Volume: "data", Path: "/data"}}},
+	}
+	if _, err := s.CreateMachine("demo", m); err != nil {
+		t.Fatalf("CreateMachine: %v", err)
+	}
+
+	// The mount survives create → GET, so a mounting machine reconciles to a
+	// no-op instead of looking drifted every apply (the bug this fixes).
+	got, err := s.GetMachine("demo", "m1")
+	if err != nil {
+		t.Fatalf("GetMachine: %v", err)
+	}
+	if len(got.Config.Mounts) != 1 || got.Config.Mounts[0].Volume != "data" || got.Config.Mounts[0].Path != "/data" {
+		t.Fatalf("mounts not persisted: %+v", got.Config.Mounts)
+	}
+
+	// Clone isolation: mutating a returned clone must not affect stored state.
+	got.Config.Mounts[0].Path = "MUTATED"
+	again, _ := s.GetMachine("demo", "m1")
+	if again.Config.Mounts[0].Path != "/data" {
+		t.Fatalf("clone aliased stored mounts: got %q, want /data", again.Config.Mounts[0].Path)
+	}
+}