fix(mpris): send actions in the phone's spelling and seek phones with SetPosition

docs/IPC_PROTOCOL.md

@@ -685,10 +685,13 @@ Send an MPRIS control action to a device.
 {"deviceId": "a1b2c3d4e5f6_...", "action": "play"}
 ```
 
-Supported actions: `"play"`, `"pause"`, `"playpause"`, `"next"`, `"previous"`,
-`"stop"`, `"raise"`, `"quit"`. Volume can be set with `"setVolume"` (requires
-an integer value field). Seek with `"seek"` (int64, offset in ms) or
-`"setPosition"` (int64, absolute position in ms).
+Supported actions: `"Play"`, `"Pause"`, `"PlayPause"`, `"Next"`, `"Previous"`,
+`"Stop"`, `"raise"`, `"quit"`. The first six are matched case-insensitively and
+sent in the spelling the phone expects, so `"playpause"` works too. Set the
+volume with a `"volume"` field (int, 0–100). Seek with `"setPosition"` (int64,
+absolute position in ms) or `"seek"` (int64, relative offset in ms, converted
+to an absolute position from the tracked playback state, since phones only
+implement absolute positioning). `action` may be omitted for any of these.
 
 **Response data:** none
 

internal/daemon/ipc_routes_mpris.go

@@ -55,7 +55,7 @@ func registerMprisRoutes(handler *ipc.Handler, devices *device.Registry, plugins
 				return ipc.Response{OK: false, Error: "no player known for this device; specify --player"}
 			}
 
-			if err := mprisPl.SendAction(dev, player, p.Action, p.Seek, p.Volume); err != nil {
+			if err := mprisPl.SendAction(dev, player, p.Action, p.Seek, p.SetPosition, p.Volume); err != nil {
 				return ipc.Response{OK: false, Error: err.Error()}
 			}
 			return ipc.Response{OK: true}

internal/ipc/proto.go

@@ -258,7 +258,9 @@ type MprisActionPayload struct {
 	Player   string `json:"player,omitempty"`
 	Action   string `json:"action,omitempty"`
 	Volume   *int   `json:"volume,omitempty"`
-	Seek     *int64 `json:"seek,omitempty"`
+	// Seek: relative ms. SetPosition: absolute ms; wins over Seek.
+	Seek        *int64 `json:"seek,omitempty"`
+	SetPosition *int64 `json:"setPosition,omitempty"`
 }
 
 type MprisRemotePlayer struct {

internal/plugins/mpris/action_test.go

@@ -0,0 +1,70 @@
+package mpris
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/bethropolis/kcd/internal/config"
+	"github.com/bethropolis/kcd/internal/events"
+	"github.com/bethropolis/kcd/internal/log"
+	"github.com/bethropolis/kcd/internal/protocol"
+)
+
+func TestCanonicalAction(t *testing.T) {
+	for in, want := range map[string]string{
+		"playpause": "PlayPause",
+		"PlayPause": "PlayPause",
+		"PLAY":      "Play",
+		"pause":     "Pause",
+		"next":      "Next",
+		"previous":  "Previous",
+		"stop":      "Stop",
+		"raise":     "raise", // unknown: unchanged
+		"":          "",
+	} {
+		if got := CanonicalAction(in); got != want {
+			t.Errorf("CanonicalAction(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
+
+type captureSender struct {
+	testSender
+	sent []*protocol.Packet
+}
+
+func (s *captureSender) Send(p *protocol.Packet) error { s.sent = append(s.sent, p); return nil }
+
+func ptr[T any](v T) *T { return &v }
+
+// A relative seek is sent as SetPosition.
+func TestSendActionSendsSeekAsSetPosition(t *testing.T) {
+	p := NewMPRISPlugin(nil, events.NewBus(log.Nop()), false, config.MPRISConfig{}, log.Nop())
+	p.remoteStates["phone"] = &NowPlaying{Player: "music", Pos: 60_000, Length: 200_000}
+
+	for _, tc := range []struct {
+		name         string
+		seek, setPos *int64
+		wantPos      int64
+	}{
+		{"forward", ptr[int64](30_000), nil, 90_000},
+		{"clamped at start", ptr[int64](-90_000), nil, 0},
+		{"clamped at end", ptr[int64](500_000), nil, 200_000},
+		{"absolute wins", ptr[int64](30_000), ptr[int64](5_000), 5_000},
+	} {
+		dev := &captureSender{testSender: testSender{id: "phone"}}
+		if err := p.SendAction(dev, "music", "", tc.seek, tc.setPos, nil); err != nil {
+			t.Fatalf("%s: %v", tc.name, err)
+		}
+		var body map[string]any
+		if err := json.Unmarshal(dev.sent[0].Body, &body); err != nil {
+			t.Fatal(err)
+		}
+		if _, ok := body["Seek"]; ok {
+			t.Errorf("%s: Seek sent alongside SetPosition: %v", tc.name, body)
+		}
+		if got, _ := body["SetPosition"].(float64); int64(got) != tc.wantPos {
+			t.Errorf("%s: SetPosition = %v, want %d", tc.name, body["SetPosition"], tc.wantPos)
+		}
+	}
+}

internal/plugins/mpris/remote.go

@@ -14,12 +14,45 @@ import (
 // SendAction sends a media control action to a remote device.
 // Sends on both kdeconnect.mpris (for Android's old MprisPlugin) and
 // kdeconnect.mpris.request (for MprisReceiverPlugin) to maximise compatibility.
-func (p *MPRISPlugin) SendAction(dev device.Sender, player, action string, seek *int64, volume *int) error {
+// canonicalActions maps lowercase action names to the phone's spelling.
+var canonicalActions = map[string]string{
+	"play":      "Play",
+	"pause":     "Pause",
+	"playpause": "PlayPause",
+	"next":      "Next",
+	"previous":  "Previous",
+	"stop":      "Stop",
+}
+
+// CanonicalAction returns the phone's spelling of action, or action if unknown.
+func CanonicalAction(action string) string {
+	if c, ok := canonicalActions[strings.ToLower(action)]; ok {
+		return c
+	}
+	return action
+}
+
+// SendAction sends a control request to a remote player. A relative seek is
+// sent as SetPosition computed from the tracked position.
+func (p *MPRISPlugin) SendAction(dev device.Sender, player, action string, seek, setPosition *int64, volume *int) error {
+	if setPosition == nil && seek != nil {
+		if state := p.RemoteState(dev.ID()); state != nil {
+			pos := max(state.Pos+*seek, 0)
+			if state.Length > 0 {
+				pos = min(pos, state.Length)
+			}
+			setPosition, seek = &pos, nil
+		}
+	}
+	if setPosition != nil {
+		seek = nil // send only one
+	}
 	body := MPRISRequest{
-		Player:    player,
-		Action:    action,
-		SetVolume: volume,
-		Seek:      seek,
+		Player:      player,
+		Action:      CanonicalAction(action),
+		SetVolume:   volume,
+		Seek:        seek,
+		SetPosition: setPosition,
 	}
 	pkt, err := protocol.NewPacket("kdeconnect.mpris.request", body)
 	if err != nil {