refactor: Move agent field parsing to shared beads package

- Add AgentFields and ParseAgentFieldsFromDescription to internal/beads/fields.go
- Update daemon/lifecycle.go to use shared parsing
- Update cmd/molecule_status.go to use shared parsing
- Remove duplicate parsing code and unused isAgentRunningByBead function

This consolidates agent bead field parsing in one place, following the pattern
established for AttachmentFields and MRFields.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/beads/fields.go

@@ -3,6 +3,105 @@ package beads
 
 import "strings"
 
+// AgentFields holds parsed fields from an agent bead's description.
+// Agent beads store their state as key: value lines in the description.
+type AgentFields struct {
+	RoleType   string // role_type: mayor, deacon, witness, refinery, polecat
+	Rig        string // rig: gastown (or null)
+	AgentState string // agent_state: idle, running, working, stopped
+	HookBead   string // hook_bead: the bead ID on the hook (or null)
+	RoleBead   string // role_bead: the role definition bead
+}
+
+// ParseAgentFields extracts agent fields from an issue's description.
+// Fields are expected as "key: value" lines. Returns nil if no agent fields found.
+func ParseAgentFields(issue *Issue) *AgentFields {
+	if issue == nil || issue.Description == "" {
+		return nil
+	}
+	return ParseAgentFieldsFromDescription(issue.Description)
+}
+
+// ParseAgentFieldsFromDescription extracts agent fields from a description string.
+// Returns nil if no agent fields found.
+func ParseAgentFieldsFromDescription(description string) *AgentFields {
+	if description == "" {
+		return nil
+	}
+
+	fields := &AgentFields{}
+	hasFields := false
+
+	for _, line := range strings.Split(description, "\n") {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+
+		colonIdx := strings.Index(line, ":")
+		if colonIdx == -1 {
+			continue
+		}
+
+		key := strings.TrimSpace(line[:colonIdx])
+		value := strings.TrimSpace(line[colonIdx+1:])
+		if value == "" || value == "null" {
+			continue
+		}
+
+		switch strings.ToLower(key) {
+		case "role_type", "role-type", "roletype":
+			fields.RoleType = value
+			hasFields = true
+		case "rig":
+			fields.Rig = value
+			hasFields = true
+		case "agent_state", "agent-state", "agentstate":
+			fields.AgentState = value
+			hasFields = true
+		case "hook_bead", "hook-bead", "hookbead":
+			fields.HookBead = value
+			hasFields = true
+		case "role_bead", "role-bead", "rolebead":
+			fields.RoleBead = value
+			hasFields = true
+		}
+	}
+
+	if !hasFields {
+		return nil
+	}
+	return fields
+}
+
+// FormatAgentFields formats AgentFields as a string suitable for an issue description.
+// Only non-empty fields are included.
+func FormatAgentFields(fields *AgentFields) string {
+	if fields == nil {
+		return ""
+	}
+
+	var lines []string
+
+	if fields.RoleType != "" {
+		lines = append(lines, "role_type: "+fields.RoleType)
+	}
+	if fields.Rig != "" {
+		lines = append(lines, "rig: "+fields.Rig)
+	}
+	if fields.AgentState != "" {
+		lines = append(lines, "agent_state: "+fields.AgentState)
+	}
+	if fields.HookBead != "" {
+		lines = append(lines, "hook_bead: "+fields.HookBead)
+	}
+	if fields.RoleBead != "" {
+		lines = append(lines, "role_bead: "+fields.RoleBead)
+	}
+
+	return strings.Join(lines, "\n")
+}
+
 // AttachmentFields holds the attachment info for pinned beads.
 // These fields track which molecule is attached to a handoff/pinned bead.
 type AttachmentFields struct {