refactor: remove proxy API (#1596)

internal/fetcher/jobs.go

@@ -0,0 +1,72 @@
+package fetcher
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"time"
+)
+
+type TriggerSource string
+
+const (
+	TriggerScheduled TriggerSource = "scheduled"
+	TriggerManual    TriggerSource = "manual"
+)
+
+var ErrJobSkipped = errors.New("protocol job skipped")
+var ErrConfigChanged = errors.New("protocol configuration changed during execution")
+
+// ConfigState embeds the common backend-owned state section in a protocol config.
+// Public config PUTs always retain this section from the latest stored config.
+type ConfigState[T any] struct {
+	State T `json:"state"`
+}
+
+// ProtocolHost is scoped to one manager. UpdateState runs against the latest
+// config under Downloader's lock; callbacks must not perform network I/O.
+type ProtocolHost struct {
+	Read        func(any) error
+	UpdateState func(func(config, state json.RawMessage) (any, error)) error
+	Fetch       func(context.Context, string, int64, func([]byte) error) ([]byte, error)
+}
+
+func ReadConfig[T any](host ProtocolHost) (*T, error) {
+	var cfg T
+	if err := host.Read(&cfg); err != nil {
+		return nil, err
+	}
+	return &cfg, nil
+}
+
+// UpdateState gives the callback a detached config snapshot and mutable state.
+// Only the state is committed; edits to the config snapshot are discarded.
+func UpdateState[C, S any](host ProtocolHost, update func(*C, *S) error) error {
+	return host.UpdateState(func(rawConfig, rawState json.RawMessage) (any, error) {
+		var cfg C
+		var state S
+		if err := json.Unmarshal(rawConfig, &cfg); err != nil {
+			return nil, err
+		}
+		if err := json.Unmarshal(rawState, &state); err != nil {
+			return nil, err
+		}
+		if err := update(&cfg, &state); err != nil {
+			return nil, err
+		}
+		return &state, nil
+	})
+}
+
+type CronJob struct {
+	Name    string
+	Every   time.Duration
+	Timeout time.Duration
+	Run     func(context.Context, TriggerSource) error
+}
+type CronProvider interface{ CronJobs(ProtocolHost) []CronJob }
+
+// ConfigNormalizer is optional. It owns protocol validation and derived fields.
+type ConfigNormalizer interface {
+	NormalizeConfig(json.RawMessage) (any, error)
+}