fix: Make ParseAgentBeadID accept any valid prefix (gt-w0fqg)

Agent bead ID validation was hardcoded to only accept "gt-" prefix, which
caused errors when spawning beads polecats (which use "bd-" prefix):

  Error: invalid agent ID: agent ID must start with 'gt-' (got "bd-beads-polecat-pearl")

Changed ParseAgentBeadID to accept any 2-3 character prefix (gt-, bd-, hq-)
instead of hardcoding "gt-". Updated tests to cover other prefixes.

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

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

internal/beads/beads.go

@@ -1011,22 +1011,27 @@ func PolecatBeadID(rig, name string) string {
 // Returns rig, role, name, and whether parsing succeeded.
 // For town-level agents, rig will be empty.
 // For singletons, name will be empty.
+// Accepts any valid prefix (e.g., "gt-", "bd-"), not just "gt-".
 func ParseAgentBeadID(id string) (rig, role, name string, ok bool) {
-	if !strings.HasPrefix(id, "gt-") {
+	// Find the prefix (everything before the first hyphen)
+	// Valid prefixes are 2-3 characters (e.g., "gt", "bd", "hq")
+	hyphenIdx := strings.Index(id, "-")
+	if hyphenIdx < 2 || hyphenIdx > 3 {
 		return "", "", "", false
 	}
-	rest := strings.TrimPrefix(id, "gt-")
+
+	rest := id[hyphenIdx+1:]
 	parts := strings.Split(rest, "-")
 
 	switch len(parts) {
 	case 1:
-		// Town-level: gt-mayor, gt-deacon
+		// Town-level: gt-mayor, bd-deacon
 		return "", parts[0], "", true
 	case 2:
-		// Rig-level singleton: gt-gastown-witness
+		// Rig-level singleton: gt-gastown-witness, bd-beads-witness
 		return parts[0], parts[1], "", true
 	case 3:
-		// Rig-level named: gt-gastown-crew-max
+		// Rig-level named: gt-gastown-crew-max, bd-beads-polecat-pearl
 		return parts[0], parts[1], parts[2], true
 	default:
 		// Handle names with hyphens: gt-gastown-polecat-my-agent-name
@@ -1038,7 +1043,8 @@ func ParseAgentBeadID(id string) (rig, role, name string, ok bool) {
 }
 
 // IsAgentSessionBead returns true if the bead ID represents an agent session molecule.
-// Agent session beads follow patterns like gt-mayor, gt-gastown-witness, gt-gastown-crew-joe.
+// Agent session beads follow patterns like gt-mayor, bd-beads-witness, gt-gastown-crew-joe.
+// Supports any valid prefix (e.g., "gt-", "bd-"), not just "gt-".
 // These are used to track agent state and update frequently, which can create noise.
 func IsAgentSessionBead(beadID string) bool {
 	_, role, _, ok := ParseAgentBeadID(beadID)

internal/beads/beads_test.go

@@ -1019,8 +1019,14 @@ func TestParseAgentBeadID(t *testing.T) {
 		{"gt-gastown-polecat-my-agent", "gastown", "polecat", "my-agent", true},
 		// Parseable but not valid agent roles (IsAgentSessionBead will reject)
 		{"gt-abc123", "", "abc123", "", true}, // Parses as town-level but not valid role
+		// Other prefixes (bd-, hq-)
+		{"bd-mayor", "", "mayor", "", true},                               // bd prefix town-level
+		{"bd-beads-witness", "beads", "witness", "", true},                // bd prefix rig-level singleton
+		{"bd-beads-polecat-pearl", "beads", "polecat", "pearl", true},     // bd prefix rig-level named
+		{"hq-mayor", "", "mayor", "", true},                               // hq prefix town-level
 		// Truly invalid patterns
-		{"bd-gastown-crew-joe", "", "", "", false}, // Wrong prefix
+		{"x-mayor", "", "", "", false},    // Prefix too short (1 char)
+		{"abcd-mayor", "", "", "", false}, // Prefix too long (4 chars)
 		{"", "", "", "", false},
 	}
 
@@ -1049,19 +1055,26 @@ func TestIsAgentSessionBead(t *testing.T) {
 		beadID string
 		want   bool
 	}{
-		// Agent session beads (should return true)
+		// Agent session beads with gt- prefix (should return true)
 		{"gt-mayor", true},
 		{"gt-deacon", true},
 		{"gt-gastown-witness", true},
 		{"gt-gastown-refinery", true},
 		{"gt-gastown-crew-joe", true},
 		{"gt-gastown-polecat-capable", true},
+		// Agent session beads with bd- prefix (should return true)
+		{"bd-mayor", true},
+		{"bd-deacon", true},
+		{"bd-beads-witness", true},
+		{"bd-beads-refinery", true},
+		{"bd-beads-crew-joe", true},
+		{"bd-beads-polecat-pearl", true},
 		// Regular work beads (should return false)
 		{"gt-abc123", false},
 		{"gt-sb6m4", false},
 		{"gt-u7dxq", false},
-		// Invalid beads
 		{"bd-abc123", false},
+		// Invalid beads
 		{"", false},
 	}
 

internal/cmd/sling.go

@@ -842,9 +842,9 @@ func detectActor() string {
 }
 
 // agentIDToBeadID converts an agent ID to its corresponding agent bead ID.
-// Uses canonical naming: gt-rig-role-name
-// Agent beads always use "gt-" prefix (required by beads validation).
-// Only issue beads use rig-specific prefixes.
+// Uses canonical naming: prefix-rig-role-name
+// This function uses "gt-" prefix by default. For non-gastown rigs, use the
+// appropriate *WithPrefix functions that accept the rig's configured prefix.
 func agentIDToBeadID(agentID string) string {
 	// Handle simple cases (town-level agents)
 	if agentID == "mayor" {