From 68fc8ca212a17a55b5bbec79c47af1d4cef6ffb7 Mon Sep 17 00:00:00 2001
From: NagIzaazShaik <176337212+shaikn6@users.noreply.github.com>
Date: Thu, 10 Sep 2026 11:03:24 -0400
Subject: [PATCH] cli: pick next -seq version by numeric max, not lexical last

nextSeqVersion took the sequence prefix from the last element of the
filepath.Glob result, which is sorted lexically. Once a project has both
single- and multi-digit versions (e.g. 9_ and 10_), '9_...' sorts after
'10_...', so 'migrate create -seq' derived the next version from 9 and
produced a duplicate version error.

Scan every match and keep the numeric maximum instead. Malformed-filename
and parse errors are still reported per element, so behaviour is
unchanged for well-formed inputs.

Fixes #1109
---
 internal/cli/commands.go      | 13 ++++++++-----
 internal/cli/commands_test.go |  1 +
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/internal/cli/commands.go b/internal/cli/commands.go
index e37ca313e..5a52df4c3 100644
--- a/internal/cli/commands.go
+++ b/internal/cli/commands.go
@@ -27,8 +27,10 @@ func nextSeqVersion(matches []string, seqDigits int) (string, error) {
 
 	nextSeq := uint64(1)
 
-	if len(matches) > 0 {
-		filename := matches[len(matches)-1]
+	// filepath.Glob returns matches in lexical order, so the highest sequence
+	// number is not necessarily last (e.g. "9_" sorts after "10_"). Scan every
+	// match and use the numeric maximum.
+	for _, filename := range matches {
 		matchSeqStr := filepath.Base(filename)
 		idx := strings.Index(matchSeqStr, "_")
 
@@ -36,15 +38,16 @@ func nextSeqVersion(matches []string, seqDigits int) (string, error) {
 			return "", fmt.Errorf("malformed migration filename: %s", filename)
 		}
 
-		var err error
 		matchSeqStr = matchSeqStr[0:idx]
-		nextSeq, err = strconv.ParseUint(matchSeqStr, 10, 64)
+		matchSeq, err := strconv.ParseUint(matchSeqStr, 10, 64)
 
 		if err != nil {
 			return "", err
 		}
 
-		nextSeq++
+		if matchSeq >= nextSeq {
+			nextSeq = matchSeq + 1
+		}
 	}
 
 	version := fmt.Sprintf("%0[2]*[1]d", nextSeq, seqDigits)
diff --git a/internal/cli/commands_test.go b/internal/cli/commands_test.go
index 798e2df77..e912bdb8b 100644
--- a/internal/cli/commands_test.go
+++ b/internal/cli/commands_test.go
@@ -88,6 +88,7 @@ func (s *CreateCmdSuite) TestNextSeqVersion() {
 		{"Single digit no int", []string{"bad_bad"}, 1, "", errors.New(`strconv.ParseUint: parsing "bad": invalid syntax`)},
 		{"Single digit negative seq", []string{"-5_test"}, 1, "", errors.New(`strconv.ParseUint: parsing "-5": invalid syntax`)},
 		{"Single digit increment", []string{"3_test", "4_test"}, 1, "5", nil},
+		{"Multi digit lexical order", []string{"0_x", "10_x", "11_x", "1_x", "2_x", "9_x"}, 6, "000012", nil},
 		{"Single digit overflow", []string{"9_test"}, 1, "", errors.New("next sequence number 10 too large, at most 1 digits are allowed")},
 		{"Zero-pad initialize", []string{}, 6, "000001", nil},
 		{"Zero-pad malformed", []string{"bad"}, 6, "", errors.New("malformed migration filename: bad")},