feat(db): add id canonicalization transform for the uniform-ids migration

db/migrations/id_canonical.go

@@ -0,0 +1,39 @@
+package migrations
+
+import (
+	"crypto/md5"
+	"encoding/hex"
+	"math/big"
+
+	"github.com/navidrome/navidrome/model/id"
+)
+
+// canonicalID maps any historical Navidrome id shape to the canonical 22-char base62 encoding
+// of a 128-bit value; unrecognized shapes (including empty and share ids) pass through unchanged.
+func canonicalID(s string) string {
+	switch len(s) {
+	case 22:
+		v, ok := new(big.Int).SetString(s, 62)
+		if !ok || v.Sign() < 0 || v.BitLen() <= 128 {
+			return s
+		}
+		sum := md5.Sum([]byte(s))
+		return id.Encode128(sum[:])
+	case 32:
+		b, err := hex.DecodeString(s)
+		if err != nil {
+			return s
+		}
+		return id.Encode128(b)
+	case 36:
+		if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' {
+			return s
+		}
+		b, err := hex.DecodeString(s[:8] + s[9:13] + s[14:18] + s[19:23] + s[24:])
+		if err != nil {
+			return s
+		}
+		return id.Encode128(b)
+	}
+	return s
+}

db/migrations/id_canonical_test.go

@@ -0,0 +1,32 @@
+package migrations
+
+import (
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("canonicalID", func() {
+	DescribeTable("transforms each historical id shape",
+		func(in, want string) {
+			Expect(canonicalID(in)).To(Equal(want))
+		},
+		Entry("hash-family id (fits 128 bits) is kept", "5cLJPkLA5DK2BADhoeotPk", "5cLJPkLA5DK2BADhoeotPk"),
+		Entry("overflowing random id is remapped via md5", "zzzzzzzzzzzzzzzzzzzzzz", "3LyqmwQBm5IRqlVjNYASwb"),
+		Entry("legacy 32-hex is re-encoded value-preserving", "e3b7fc2ae9447bbec37a13bf916e3cf6", "6VHl3uR4kss6sUPKA8Cwnk"),
+		Entry("playlist uuid is re-encoded value-preserving", "f47ac10b-58cc-4372-a567-0e02b2c3d479", "7rke2SAWaicSeSYzkhww6R"),
+		Entry("empty string passes through", "", ""),
+		Entry("share id (10 chars) passes through", "aB3xY9kQz1", "aB3xY9kQz1"),
+		Entry("truncated Finamp id (16 chars) passes through", "0123456789abcdef", "0123456789abcdef"),
+		Entry("22 chars with non-base62 char passes through", "!!!!!!!!!!!!!!!!!!!!!!", "!!!!!!!!!!!!!!!!!!!!!!"),
+		Entry("32 chars non-hex passes through", "zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz", "zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz"),
+		Entry("36 chars without uuid dashes passes through", "000000000000000000000000000000000000", "000000000000000000000000000000000000"),
+	)
+
+	It("is idempotent for every shape", func() {
+		for _, s := range []string{"5cLJPkLA5DK2BADhoeotPk", "zzzzzzzzzzzzzzzzzzzzzz",
+			"e3b7fc2ae9447bbec37a13bf916e3cf6", "f47ac10b-58cc-4372-a567-0e02b2c3d479"} {
+			once := canonicalID(s)
+			Expect(canonicalID(once)).To(Equal(once))
+		}
+	})
+})

db/migrations/migrations_suite_test.go

@@ -0,0 +1,16 @@
+package migrations
+
+import (
+	"testing"
+
+	"github.com/navidrome/navidrome/log"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+// tests.Init is omitted: the tests package imports db, which imports this package.
+func TestMigrations(t *testing.T) {
+	log.SetLevel(log.LevelFatal)
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Migrations Suite")
+}