refactor: remove unused bd pin/unpin/hook commands (bd-x0zl)

Analysis found these commands are dead code:
- gt never calls `bd pin` - uses `bd update --status=pinned` instead
- Beads.Pin() wrapper exists but is never called
- bd hook functionality duplicated by gt mol status
- Code comment says "pinned field is cosmetic for bd hook visibility"

Removed:
- cmd/bd/pin.go
- cmd/bd/unpin.go
- cmd/bd/hook.go

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

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

internal/storage/memory/memory.go

@@ -1097,10 +1097,16 @@ func (m *MemoryStorage) getOpenBlockers(issueID string) []string {
 
 // GetBlockedIssues returns issues that are blocked by other issues
 // Note: Pinned issues are excluded from the output (beads-ei4)
-func (m *MemoryStorage) GetBlockedIssues(ctx context.Context) ([]*types.BlockedIssue, error) {
+func (m *MemoryStorage) GetBlockedIssues(ctx context.Context, filter types.WorkFilter) ([]*types.BlockedIssue, error) {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
+	// Build set of descendant IDs if parent filter is specified
+	var descendantIDs map[string]bool
+	if filter.ParentID != nil {
+		descendantIDs = m.getAllDescendants(*filter.ParentID)
+	}
+
 	var results []*types.BlockedIssue
 
 	for _, issue := range m.issues {
@@ -1114,6 +1120,11 @@ func (m *MemoryStorage) GetBlockedIssues(ctx context.Context) ([]*types.BlockedI
 			continue
 		}
 
+		// Parent filtering: only include descendants of specified parent
+		if descendantIDs != nil && !descendantIDs[issue.ID] {
+			continue
+		}
+
 		blockers := m.getOpenBlockers(issue.ID)
 		// Issue is "blocked" if: status is blocked, status is deferred, or has open blockers
 		if issue.Status != types.StatusBlocked && issue.Status != types.StatusDeferred && len(blockers) == 0 {
@@ -1149,6 +1160,27 @@ func (m *MemoryStorage) GetBlockedIssues(ctx context.Context) ([]*types.BlockedI
 	return results, nil
 }
 
+// getAllDescendants returns all descendant IDs of a parent issue recursively
+func (m *MemoryStorage) getAllDescendants(parentID string) map[string]bool {
+	descendants := make(map[string]bool)
+	m.collectDescendants(parentID, descendants)
+	return descendants
+}
+
+// collectDescendants recursively collects all descendants of a parent
+func (m *MemoryStorage) collectDescendants(parentID string, descendants map[string]bool) {
+	for issueID, deps := range m.dependencies {
+		for _, dep := range deps {
+			if dep.Type == types.DepParentChild && dep.DependsOnID == parentID {
+				if !descendants[issueID] {
+					descendants[issueID] = true
+					m.collectDescendants(issueID, descendants)
+				}
+			}
+		}
+	}
+}
+
 func (m *MemoryStorage) GetEpicsEligibleForClosure(ctx context.Context) ([]*types.EpicStatus, error) {
 	return nil, nil
 }
@@ -1184,6 +1216,58 @@ func (m *MemoryStorage) GetStaleIssues(ctx context.Context, filter types.StaleFi
 	return stale, nil
 }
 
+// GetNewlyUnblockedByClose returns issues that became unblocked when the given issue was closed.
+// This is used by the --suggest-next flag on bd close (GH#679).
+func (m *MemoryStorage) GetNewlyUnblockedByClose(ctx context.Context, closedIssueID string) ([]*types.Issue, error) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	var unblocked []*types.Issue
+
+	// Find issues that depend on the closed issue
+	for issueID, deps := range m.dependencies {
+		issue, exists := m.issues[issueID]
+		if !exists {
+			continue
+		}
+
+		// Only consider open/in_progress, non-pinned issues
+		if issue.Status != types.StatusOpen && issue.Status != types.StatusInProgress {
+			continue
+		}
+		if issue.Pinned {
+			continue
+		}
+
+		// Check if this issue depended on the closed issue
+		dependedOnClosed := false
+		for _, dep := range deps {
+			if dep.DependsOnID == closedIssueID && dep.Type == types.DepBlocks {
+				dependedOnClosed = true
+				break
+			}
+		}
+
+		if !dependedOnClosed {
+			continue
+		}
+
+		// Check if now unblocked (no remaining open blockers)
+		blockers := m.getOpenBlockers(issueID)
+		if len(blockers) == 0 {
+			issueCopy := *issue
+			unblocked = append(unblocked, &issueCopy)
+		}
+	}
+
+	// Sort by priority ascending
+	sort.Slice(unblocked, func(i, j int) bool {
+		return unblocked[i].Priority < unblocked[j].Priority
+	})
+
+	return unblocked, nil
+}
+
 func (m *MemoryStorage) AddComment(ctx context.Context, issueID, actor, comment string) error {
 	return nil
 }