diff --git a/cmd/bd/audit.go b/cmd/bd/audit.go
index 2003842a..567a9319 100644
--- a/cmd/bd/audit.go
+++ b/cmd/bd/audit.go
@@ -160,6 +160,9 @@ func init() {
 	auditLabelCmd.Flags().StringVar(&auditLabelValue, "label", "", `Label value (e.g. "good" or "bad")`)
 	auditLabelCmd.Flags().StringVar(&auditLabelReason, "reason", "", "Reason for label")
 
+	// Issue ID completions
+	auditCmd.ValidArgsFunction = issueIDCompletion
+
 	auditCmd.AddCommand(auditRecordCmd)
 	auditCmd.AddCommand(auditLabelCmd)
 	rootCmd.AddCommand(auditCmd)
diff --git a/cmd/bd/comments.go b/cmd/bd/comments.go
index 5bbbcd3d..8e6ac7bc 100644
--- a/cmd/bd/comments.go
+++ b/cmd/bd/comments.go
@@ -218,11 +218,16 @@ func init() {
 	commentsCmd.AddCommand(commentsAddCmd)
 	commentsAddCmd.Flags().StringP("file", "f", "", "Read comment text from file")
 	commentsAddCmd.Flags().StringP("author", "a", "", "Add author to comment")
-	
+
 	// Add the same flags to the alias
 	commentCmd.Flags().StringP("file", "f", "", "Read comment text from file")
 	commentCmd.Flags().StringP("author", "a", "", "Add author to comment")
-	
+
+	// Issue ID completions
+	commentsCmd.ValidArgsFunction = issueIDCompletion
+	commentsAddCmd.ValidArgsFunction = issueIDCompletion
+	commentCmd.ValidArgsFunction = issueIDCompletion
+
 	rootCmd.AddCommand(commentsCmd)
 	rootCmd.AddCommand(commentCmd)
 }
diff --git a/cmd/bd/completions.go b/cmd/bd/completions.go
index cedc5e0c..6f860a7c 100644
--- a/cmd/bd/completions.go
+++ b/cmd/bd/completions.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"fmt"
 	"path/filepath"
-	"strings"
 	"time"
 
 	"github.com/spf13/cobra"
@@ -51,8 +50,10 @@ func issueIDCompletion(cmd *cobra.Command, args []string, toComplete string) ([]
 		defer currentStore.Close()
 	}
 
-	// Use SearchIssues with empty query and default filter to get all issues
-	filter := types.IssueFilter{}
+	// Use SearchIssues with IDPrefix filter to efficiently query matching issues
+	filter := types.IssueFilter{
+		IDPrefix: toComplete, // Filter at database level for better performance
+	}
 	issues, err := currentStore.SearchIssues(ctx, "", filter)
 	if err != nil {
 		// If we can't list issues, return empty completion
@@ -62,11 +63,6 @@ func issueIDCompletion(cmd *cobra.Command, args []string, toComplete string) ([]
 	// Build completion list
 	completions := make([]string, 0, len(issues))
 	for _, issue := range issues {
-		// Filter based on what's already typed
-		if toComplete != "" && !strings.HasPrefix(issue.ID, toComplete) {
-			continue
-		}
-
 		// Format: ID\tTitle (shown during completion)
 		completions = append(completions, fmt.Sprintf("%s\t%s", issue.ID, issue.Title))
 	}
diff --git a/cmd/bd/delete.go b/cmd/bd/delete.go
index ffc943d2..9acf7590 100644
--- a/cmd/bd/delete.go
+++ b/cmd/bd/delete.go
@@ -833,5 +833,6 @@ func init() {
 	deleteCmd.Flags().Bool("cascade", false, "Recursively delete all dependent issues")
 	deleteCmd.Flags().Bool("hard", false, "Permanently delete (skip tombstone, cannot be recovered via sync)")
 	deleteCmd.Flags().String("reason", "", "Reason for deletion (stored in tombstone for audit trail)")
+	deleteCmd.ValidArgsFunction = issueIDCompletion
 	rootCmd.AddCommand(deleteCmd)
 }
diff --git a/cmd/bd/dep.go b/cmd/bd/dep.go
index 8b00229a..7637d369 100644
--- a/cmd/bd/dep.go
+++ b/cmd/bd/dep.go
@@ -1167,6 +1167,12 @@ func init() {
 	depListCmd.Flags().String("direction", "down", "Direction: 'down' (dependencies), 'up' (dependents)")
 	depListCmd.Flags().StringP("type", "t", "", "Filter by dependency type (e.g., tracks, blocks, parent-child)")
 
+	// Issue ID completions for dep subcommands
+	depAddCmd.ValidArgsFunction = issueIDCompletion
+	depRemoveCmd.ValidArgsFunction = issueIDCompletion
+	depListCmd.ValidArgsFunction = issueIDCompletion
+	depTreeCmd.ValidArgsFunction = issueIDCompletion
+
 	depCmd.AddCommand(depAddCmd)
 	depCmd.AddCommand(depRemoveCmd)
 	depCmd.AddCommand(depListCmd)
diff --git a/cmd/bd/duplicate.go b/cmd/bd/duplicate.go
index 51f7574c..5b635aab 100644
--- a/cmd/bd/duplicate.go
+++ b/cmd/bd/duplicate.go
@@ -50,10 +50,12 @@ var (
 func init() {
 	duplicateCmd.Flags().StringVar(&duplicateOf, "of", "", "Canonical issue ID (required)")
 	_ = duplicateCmd.MarkFlagRequired("of") // Only fails if flag missing (caught in tests)
+	duplicateCmd.ValidArgsFunction = issueIDCompletion
 	rootCmd.AddCommand(duplicateCmd)
 
 	supersedeCmd.Flags().StringVar(&supersededWith, "with", "", "Replacement issue ID (required)")
 	_ = supersedeCmd.MarkFlagRequired("with") // Only fails if flag missing (caught in tests)
+	supersedeCmd.ValidArgsFunction = issueIDCompletion
 	rootCmd.AddCommand(supersedeCmd)
 }
 
diff --git a/cmd/bd/gate.go b/cmd/bd/gate.go
index 8e3f0914..b6f669dd 100644
--- a/cmd/bd/gate.go
+++ b/cmd/bd/gate.go
@@ -871,6 +871,11 @@ func init() {
 	gateCheckCmd.Flags().BoolP("escalate", "e", false, "Escalate failed/expired gates")
 	gateCheckCmd.Flags().IntP("limit", "l", 100, "Limit results (default 100)")
 
+	// Issue ID completions
+	gateShowCmd.ValidArgsFunction = issueIDCompletion
+	gateResolveCmd.ValidArgsFunction = issueIDCompletion
+	gateAddWaiterCmd.ValidArgsFunction = issueIDCompletion
+
 	// Add subcommands
 	gateCmd.AddCommand(gateListCmd)
 	gateCmd.AddCommand(gateShowCmd)
diff --git a/cmd/bd/graph.go b/cmd/bd/graph.go
index d4e585dd..6fb23cdc 100644
--- a/cmd/bd/graph.go
+++ b/cmd/bd/graph.go
@@ -117,6 +117,7 @@ Colors indicate status:
 }
 
 func init() {
+	graphCmd.ValidArgsFunction = issueIDCompletion
 	rootCmd.AddCommand(graphCmd)
 }
 
diff --git a/cmd/bd/label.go b/cmd/bd/label.go
index a56fcbfd..94febc55 100644
--- a/cmd/bd/label.go
+++ b/cmd/bd/label.go
@@ -314,6 +314,11 @@ var labelListAllCmd = &cobra.Command{
 	},
 }
 func init() {
+	// Issue ID completions
+	labelAddCmd.ValidArgsFunction = issueIDCompletion
+	labelRemoveCmd.ValidArgsFunction = issueIDCompletion
+	labelListCmd.ValidArgsFunction = issueIDCompletion
+
 	labelCmd.AddCommand(labelAddCmd)
 	labelCmd.AddCommand(labelRemoveCmd)
 	labelCmd.AddCommand(labelListCmd)
diff --git a/cmd/bd/move.go b/cmd/bd/move.go
index 496b24c9..00487ed6 100644
--- a/cmd/bd/move.go
+++ b/cmd/bd/move.go
@@ -276,5 +276,6 @@ func init() {
 	moveCmd.Flags().String("to", "", "Target rig or prefix (required)")
 	moveCmd.Flags().Bool("keep-open", false, "Keep the source issue open (don't close it)")
 	moveCmd.Flags().Bool("skip-deps", false, "Skip dependency remapping")
+	moveCmd.ValidArgsFunction = issueIDCompletion
 	rootCmd.AddCommand(moveCmd)
 }
diff --git a/cmd/bd/refile.go b/cmd/bd/refile.go
index 9df057a8..02a3cece 100644
--- a/cmd/bd/refile.go
+++ b/cmd/bd/refile.go
@@ -160,5 +160,6 @@ Examples:
 
 func init() {
 	refileCmd.Flags().Bool("keep-open", false, "Keep the source issue open (don't close it)")
+	refileCmd.ValidArgsFunction = issueIDCompletion
 	rootCmd.AddCommand(refileCmd)
 }
diff --git a/cmd/bd/relate.go b/cmd/bd/relate.go
index 7610559b..1830f211 100644
--- a/cmd/bd/relate.go
+++ b/cmd/bd/relate.go
@@ -41,6 +41,10 @@ Example:
 }
 
 func init() {
+	// Issue ID completions
+	relateCmd.ValidArgsFunction = issueIDCompletion
+	unrelateCmd.ValidArgsFunction = issueIDCompletion
+
 	// Add as subcommands of dep
 	depCmd.AddCommand(relateCmd)
 	depCmd.AddCommand(unrelateCmd)
diff --git a/internal/storage/memory/memory.go b/internal/storage/memory/memory.go
index 3b37fe87..f52de112 100644
--- a/internal/storage/memory/memory.go
+++ b/internal/storage/memory/memory.go
@@ -620,6 +620,11 @@ func (m *MemoryStorage) SearchIssues(ctx context.Context, query string, filter t
 			}
 		}
 
+		// ID prefix filtering (for shell completion)
+		if filter.IDPrefix != "" && !strings.HasPrefix(issue.ID, filter.IDPrefix) {
+			continue
+		}
+
 		// Parent filtering (bd-yqhh): filter children by parent issue
 		if filter.ParentID != nil {
 			isChild := false
diff --git a/internal/storage/sqlite/queries.go b/internal/storage/sqlite/queries.go
index 9d216254..13fcaef9 100644
--- a/internal/storage/sqlite/queries.go
+++ b/internal/storage/sqlite/queries.go
@@ -1836,6 +1836,12 @@ func (s *SQLiteStorage) SearchIssues(ctx context.Context, query string, filter t
 		whereClauses = append(whereClauses, fmt.Sprintf("id IN (%s)", strings.Join(placeholders, ", ")))
 	}
 
+	// ID prefix filtering (for shell completion)
+	if filter.IDPrefix != "" {
+		whereClauses = append(whereClauses, "id LIKE ?")
+		args = append(args, filter.IDPrefix+"%")
+	}
+
 	// Wisp filtering
 	if filter.Ephemeral != nil {
 		if *filter.Ephemeral {
diff --git a/internal/storage/sqlite/transaction.go b/internal/storage/sqlite/transaction.go
index 06fbcab1..9f2a6ab5 100644
--- a/internal/storage/sqlite/transaction.go
+++ b/internal/storage/sqlite/transaction.go
@@ -1181,6 +1181,12 @@ func (t *sqliteTxStorage) SearchIssues(ctx context.Context, query string, filter
 		whereClauses = append(whereClauses, fmt.Sprintf("id IN (%s)", strings.Join(placeholders, ", ")))
 	}
 
+	// ID prefix filtering (for shell completion)
+	if filter.IDPrefix != "" {
+		whereClauses = append(whereClauses, "id LIKE ?")
+		args = append(args, filter.IDPrefix+"%")
+	}
+
 	// Wisp filtering
 	if filter.Ephemeral != nil {
 		if *filter.Ephemeral {
diff --git a/internal/types/types.go b/internal/types/types.go
index b6fa493b..e958b985 100644
--- a/internal/types/types.go
+++ b/internal/types/types.go
@@ -758,7 +758,8 @@ type IssueFilter struct {
 	Labels      []string  // AND semantics: issue must have ALL these labels
 	LabelsAny   []string  // OR semantics: issue must have AT LEAST ONE of these labels
 	TitleSearch string
-	IDs         []string  // Filter by specific issue IDs
+	IDs         []string // Filter by specific issue IDs
+	IDPrefix    string   // Filter by ID prefix (for shell completion)
 	Limit       int
 	
 	// Pattern matching