4 files changed, 53 insertions, 12 deletions
diff --git a/internal/askcli/dispatch_test.go b/internal/askcli/dispatch_test.go
index ebd7273..079d156 100644
--- a/internal/askcli/dispatch_test.go
+++ b/internal/askcli/dispatch_test.go
@@ -57,6 +57,18 @@ func TestDispatcher_UnknownSubcommand(t *testing.T) {
 }
 
 func TestDispatcher_CompleteUUIDsSubcommand(t *testing.T) {
+	// Use a temp dir for the alias cache so this test is hermetic and does
+	// not depend on cache state left by other tests.
+	dir := t.TempDir()
+	oldRoot := taskAliasCacheRoot
+	oldNow := nowTaskAliasCache
+	taskAliasCacheRoot = func() (string, error) { return filepath.Join(dir, "hexai"), nil }
+	nowTaskAliasCache = func() time.Time { return time.Date(2026, 3, 27, 12, 0, 0, 0, time.UTC) }
+	defer func() {
+		taskAliasCacheRoot = oldRoot
+		nowTaskAliasCache = oldNow
+	}()
+
 	d := NewDispatcher(&spyRunner{runFn: func(ctx context.Context, args []string, stdin io.Reader, stdout, stderr io.Writer) (int, error) {
 		if strings.Join(args, " ") != "status:pending export" {
 			t.Fatalf("args = %v, want pending export", args)
diff --git a/internal/askcli/task_alias_cache.go b/internal/askcli/task_alias_cache.go
index 3ea5dff..21967d8 100644
--- a/internal/askcli/task_alias_cache.go
+++ b/internal/askcli/task_alias_cache.go
@@ -107,7 +107,10 @@ func taskAliasCachePath() (string, error) {
 	if err != nil {
 		return "", fmt.Errorf("resolve cache dir: %w", err)
 	}
-	return filepath.Join(dir, "ask", "task-aliases-v1.json"), nil
+	// v2 uses reversed alias strings (e.g. "10" instead of "01") so that the
+	// first character varies more often, improving shell auto-completion. The
+	// old v1 file is intentionally abandoned so the mapping starts fresh.
+	return filepath.Join(dir, "ask", "task-aliases-v2.json"), nil
 }
 
 func (c *taskAliasCache) validate() error {
@@ -273,6 +276,21 @@ func (e taskAliasCacheEntry) lastTouchedAt() time.Time {
 	return e.CreatedAt
 }
 
+// reverseString returns s with its bytes in reverse order. Alias strings only
+// ever contain ASCII characters so byte-level reversal is correct.
+func reverseString(s string) string {
+	b := []byte(s)
+	for i, j := 0, len(b)-1; i < j; i, j = i+1, j-1 {
+		b[i], b[j] = b[j], b[i]
+	}
+	return string(b)
+}
+
+// encodeTaskAliasID converts a monotonically-increasing counter to a short
+// alphanumeric string and then reverses it. The reversal ensures that the
+// first character of the alias varies as quickly as possible, which makes
+// shell tab-completion more effective (e.g. "1", "2", ... "z", "00" becomes
+// "1", "2", ..., "z", "00"; then "10", "20", ... instead of "00", "10", ...).
 func encodeTaskAliasID(id uint64) string {
 	const alphabet = "0123456789abcdefghijklmnopqrstuvwxyz"
 
@@ -290,9 +308,14 @@ func encodeTaskAliasID(id uint64) string {
 		buf[i] = alphabet[remaining%uint64(len(alphabet))]
 		remaining /= uint64(len(alphabet))
 	}
-	return string(buf)
+	// Reverse so that the least-significant digit comes first, keeping the
+	// leading character diverse across consecutive IDs.
+	return reverseString(string(buf))
 }
 
+// decodeTaskAliasID is the inverse of encodeTaskAliasID. It reverses the alias
+// string to restore the canonical (most-significant-digit-first) form before
+// decoding.
 func decodeTaskAliasID(alias string) (uint64, bool) {
 	const alphabet = "0123456789abcdefghijklmnopqrstuvwxyz"
 
@@ -300,7 +323,9 @@ func decodeTaskAliasID(alias string) (uint64, bool) {
 		return 0, false
 	}
 
-	width := len(alias)
+	// Reverse the alias back to the canonical form before decoding.
+	canonical := reverseString(alias)
+	width := len(canonical)
 	var id uint64
 	blockSize := uint64(len(alphabet))
 	for i := 1; i < width; i++ {
@@ -309,7 +334,7 @@ func decodeTaskAliasID(alias string) (uint64, bool) {
 	}
 
 	var value uint64
-	for _, r := range alias {
+	for _, r := range canonical {
 		index := int64(-1)
 		for i, candidate := range alphabet {
 			if r == candidate {
diff --git a/internal/askcli/task_alias_cache_test.go b/internal/askcli/task_alias_cache_test.go
index f792585..92d528b 100644
--- a/internal/askcli/task_alias_cache_test.go
+++ b/internal/askcli/task_alias_cache_test.go
@@ -11,6 +11,8 @@ import (
 func TestEncodeTaskAliasID(t *testing.T) {
 	t.Parallel()
 
+	// Aliases are stored in reversed form so that the first character varies
+	// quickly across consecutive IDs, improving shell tab-completion.
 	tests := []struct {
 		id   uint64
 		want string
@@ -20,12 +22,12 @@ func TestEncodeTaskAliasID(t *testing.T) {
 		{id: 10, want: "a"},
 		{id: 35, want: "z"},
 		{id: 36, want: "00"},
-		{id: 37, want: "01"},
-		{id: 71, want: "0z"},
-		{id: 72, want: "10"},
+		{id: 37, want: "10"},
+		{id: 71, want: "z0"},
+		{id: 72, want: "01"},
 		{id: 1331, want: "zz"},
 		{id: 1332, want: "000"},
-		{id: 1333, want: "001"},
+		{id: 1333, want: "100"},
 	}
 
 	for _, tc := range tests {
@@ -38,6 +40,8 @@ func TestEncodeTaskAliasID(t *testing.T) {
 func TestDecodeTaskAliasID(t *testing.T) {
 	t.Parallel()
 
+	// Aliases are in reversed form (matching encodeTaskAliasID output), so
+	// decodeTaskAliasID must reverse them back before decoding.
 	tests := []struct {
 		alias string
 		want  uint64
@@ -46,7 +50,7 @@ func TestDecodeTaskAliasID(t *testing.T) {
 		{alias: "0", want: 0, ok: true},
 		{alias: "z", want: 35, ok: true},
 		{alias: "00", want: 36, ok: true},
-		{alias: "01", want: 37, ok: true},
+		{alias: "10", want: 37, ok: true},
 		{alias: "zz", want: 1331, ok: true},
 		{alias: "000", want: 1332, ok: true},
 		{alias: "", ok: false},
@@ -163,8 +167,8 @@ func TestEnsureTaskAliases_PrunesExpiredEntriesWithoutReusingIDs(t *testing.T) {
 	if aliases["fresh"] != "00" {
 		t.Fatalf("fresh alias = %q, want 00", aliases["fresh"])
 	}
-	if aliases["new-task"] != "01" {
-		t.Fatalf("new-task alias = %q, want 01", aliases["new-task"])
+	if aliases["new-task"] != "10" {
+		t.Fatalf("new-task alias = %q, want 10", aliases["new-task"])
 	}
 
 	cache = readTaskAliasCacheForTest(t, path)
diff --git a/internal/version.go b/internal/version.go
index c2ffb03..b9f06e0 100644
--- a/internal/version.go
+++ b/internal/version.go
@@ -1,4 +1,4 @@
 // Package internal provides the Hexai semantic version identifier used by CLI and LSP binaries.
 package internal
 
-const Version = "0.28.1"
+const Version = "0.28.2"