Add label filtering to bd list with AND/OR semantics

- Add --label flag for AND filtering (must have ALL labels)
- Add --label-any flag for OR filtering (must have AT LEAST ONE label)
- Add normalizeLabels() helper to trim, dedupe, and clean inputs
- Fix RPC title filtering parity bug (forward via Query field)
- Add comprehensive tests for label filtering including combined AND+OR
- Update documentation in README and CHANGELOG
- Improve flag help text to clarify combined semantics

Closes bd-161

internal/rpc/protocol.go

@@ -81,13 +81,15 @@ type CloseArgs struct {
 
 // ListArgs represents arguments for the list operation
 type ListArgs struct {
-	Query     string `json:"query,omitempty"`
-	Status    string `json:"status,omitempty"`
-	Priority  *int   `json:"priority,omitempty"`
-	IssueType string `json:"issue_type,omitempty"`
-	Assignee  string `json:"assignee,omitempty"`
-	Label     string `json:"label,omitempty"`
-	Limit     int    `json:"limit,omitempty"`
+	Query     string   `json:"query,omitempty"`
+	Status    string   `json:"status,omitempty"`
+	Priority  *int     `json:"priority,omitempty"`
+	IssueType string   `json:"issue_type,omitempty"`
+	Assignee  string   `json:"assignee,omitempty"`
+	Label     string   `json:"label,omitempty"`     // Deprecated: use Labels
+	Labels    []string `json:"labels,omitempty"`    // AND semantics
+	LabelsAny []string `json:"labels_any,omitempty"` // OR semantics
+	Limit     int      `json:"limit,omitempty"`
 }
 
 // ShowArgs represents arguments for the show operation

internal/rpc/server.go

@@ -28,6 +28,24 @@ import (
 // It's set as a var so it can be initialized from main
 var ServerVersion = "0.9.10"
 
+// normalizeLabels trims whitespace, removes empty strings, and deduplicates labels
+func normalizeLabels(ss []string) []string {
+	seen := make(map[string]struct{})
+	out := make([]string, 0, len(ss))
+	for _, s := range ss {
+		s = strings.TrimSpace(s)
+		if s == "" {
+			continue
+		}
+		if _, ok := seen[s]; ok {
+			continue
+		}
+		seen[s] = struct{}{}
+		out = append(out, s)
+	}
+	return out
+}
+
 // StorageCacheEntry holds a cached storage with metadata for eviction
 type StorageCacheEntry struct {
 	store      storage.Storage
@@ -899,6 +917,18 @@ func (s *Server) handleList(req *Request) Response {
 	if listArgs.Priority != nil {
 		filter.Priority = listArgs.Priority
 	}
+	// Normalize and apply label filters
+	labels := normalizeLabels(listArgs.Labels)
+	labelsAny := normalizeLabels(listArgs.LabelsAny)
+	// Support both old single Label and new Labels array
+	if len(labels) > 0 {
+		filter.Labels = labels
+	} else if listArgs.Label != "" {
+		filter.Labels = []string{strings.TrimSpace(listArgs.Label)}
+	}
+	if len(labelsAny) > 0 {
+		filter.LabelsAny = labelsAny
+	}
 
 	ctx := s.reqCtx(req)
 	issues, err := store.SearchIssues(ctx, listArgs.Query, filter)