feat(acp/handlers): session/request_permission auto-reject

internal/acp/handlers/server_permission.go

@@ -0,0 +1,67 @@
+package handlers
+
+import (
+	"context"
+	"encoding/json"
+	"strings"
+)
+
+// PermissionHandler handles session/request_permission (spec §5.1).
+//
+// MVP behaviour (decision §1 #8 + §10 misc #1): fs.* tool calls are answered
+// directly by the server (so they never reach this handler). Other tool calls
+// default to "reject_once" — fully automated, no human-in-the-loop.
+type PermissionHandler struct{}
+
+// NewPermissionHandler constructs a PermissionHandler.
+func NewPermissionHandler() *PermissionHandler { return &PermissionHandler{} }
+
+type permissionParams struct {
+	SessionID string          `json:"sessionId"`
+	ToolCall  json.RawMessage `json:"toolCall"`
+	Options   []permOption    `json:"options"`
+}
+
+type permOption struct {
+	ID   string `json:"id"`
+	Name string `json:"name,omitempty"`
+}
+
+type permOutcomeSelected struct {
+	ID string `json:"id"`
+}
+
+type permOutcome struct {
+	Selected *permOutcomeSelected `json:"selected,omitempty"`
+}
+
+type permResult struct {
+	Outcome permOutcome `json:"outcome"`
+}
+
+// Handle picks the first option whose ID looks like a "reject" choice; if none
+// matches, falls back to the first option. Aligns with spec §10 misc #4
+// ("default reject").
+func (h *PermissionHandler) Handle(_ context.Context, _ SessionContext, paramsJSON json.RawMessage) FsResult {
+	var p permissionParams
+	if err := json.Unmarshal(paramsJSON, &p); err != nil {
+		return FsResult{Err: &FsError{Code: -32602, Message: "invalid params: " + err.Error()}}
+	}
+	chosen := ""
+	for _, opt := range p.Options {
+		lc := strings.ToLower(opt.ID)
+		if strings.Contains(lc, "reject") || strings.Contains(lc, "deny") || strings.Contains(lc, "no") {
+			chosen = opt.ID
+			break
+		}
+	}
+	if chosen == "" && len(p.Options) > 0 {
+		chosen = p.Options[0].ID
+	}
+	if chosen == "" {
+		out, _ := json.Marshal(permResult{Outcome: permOutcome{}})
+		return FsResult{OK: out}
+	}
+	out, _ := json.Marshal(permResult{Outcome: permOutcome{Selected: &permOutcomeSelected{ID: chosen}}})
+	return FsResult{OK: out}
+}