From ab4cdb437721e9acf03c97e27653d06cc6400826 Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 29 Oct 2025 12:36:52 +0200
Subject: [PATCH 01/15] Add `id` module

---
 .github/dependabot.yml       |  14 ++++
 .github/workflows/sub_id.yml |  26 ++++++++
 http/encoding/encoding.go    |  11 ----
 id/.mockery.yml              |  23 +++++++
 id/Makefile                  |   8 +++
 id/README.md                 |   7 ++
 id/go.mod                    |  14 ++++
 id/go.sum                    |  14 ++++
 id/uuid.go                   |  77 ++++++++++++++++++++++
 id/uuid_test.go              | 121 +++++++++++++++++++++++++++++++++++
 10 files changed, 304 insertions(+), 11 deletions(-)
 create mode 100644 .github/workflows/sub_id.yml
 create mode 100644 id/.mockery.yml
 create mode 100644 id/Makefile
 create mode 100644 id/README.md
 create mode 100644 id/go.mod
 create mode 100644 id/go.sum
 create mode 100644 id/uuid.go
 create mode 100644 id/uuid_test.go

diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 839a5c8..1e66466 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -51,6 +51,20 @@ updates:
         patterns:
           - "*"
 
+  - package-ecosystem: "gomod"
+    directory: "/id"
+    schedule:
+      interval: "daily"
+    commit-message:
+      prefix: "[id]"
+      include: "scope"
+    allow:
+      - dependency-type: all
+    groups:
+      main:
+        patterns:
+          - "*"
+
   - package-ecosystem: "gomod"
     directory: "/tst"
     schedule:
diff --git a/.github/workflows/sub_id.yml b/.github/workflows/sub_id.yml
new file mode 100644
index 0000000..b40abba
--- /dev/null
+++ b/.github/workflows/sub_id.yml
@@ -0,0 +1,26 @@
+# yaml-language-server: $schema=https://json.schemastore.org/github-workflow.json
+name: id
+
+on:
+  workflow_dispatch: {}
+
+  push:
+    branches: [ main ]
+
+  pull_request:
+    branches: [ main ]
+    paths:
+      - .golangci.yml
+      - tools/**
+      - .github/workflows/ci.yml
+      - .github/workflows/sub_id.yml
+      - id/**
+
+jobs:
+
+  ci:
+    uses: ./.github/workflows/ci.yml
+    with:
+      mod_path: id
+    secrets:
+      CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
diff --git a/http/encoding/encoding.go b/http/encoding/encoding.go
index 585fb13..139ee3e 100644
--- a/http/encoding/encoding.go
+++ b/http/encoding/encoding.go
@@ -1,7 +1,6 @@
 package encoding
 
 import (
-	"encoding/base64"
 	"errors"
 	"net/url"
 	"strings"
@@ -16,16 +15,6 @@ import (
 	"golang.org/x/text/encoding/unicode"
 )
 
-// URLSafeBase64 returns a [base64.Encoding] based on [base64.URLEncoding] replacing the default padding character ('=') padding character to a url safe one ('~').
-// In URL parameters, the following characters are considered safe and do not need encoding [rfc3986](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.1):
-// Alphabetic characters: A-Z, a-z
-// Digits: 0-9
-// Hyphen: -
-// Underscore: _
-// Period: .
-// Tilde: ~
-var URLSafeBase64 = base64.URLEncoding.WithPadding('~')
-
 // RFC5987ExtendedNotationParameterValue decodes RFC 5987 encoded filenames expecting the extended notation
 // (charset  "'" [ language ] "'" value-chars)
 // example: UTF-8'en'file%20name.jpg
diff --git a/id/.mockery.yml b/id/.mockery.yml
new file mode 100644
index 0000000..8163587
--- /dev/null
+++ b/id/.mockery.yml
@@ -0,0 +1,23 @@
+# https://vektra.github.io/mockery/v3.5/configuration/
+
+log-level: info
+formatter: goimports
+force-file-write: true
+require-template-schema-exists: true
+
+all: true
+recursive: false
+dir: '{{.InterfaceDir}}'
+filename: mocks_test.go
+pkgname: '{{.SrcPackageName}}'
+structname: '{{.Mock}}{{.InterfaceName}}'
+
+# https://vektra.github.io/mockery/v3.5/template/
+template: testify
+template-schema: '{{.Template}}.schema.json'
+
+packages:
+  github.com/ifnotnil/x/id:
+    config:
+        all: true
+        recursive: true
diff --git a/id/Makefile b/id/Makefile
new file mode 100644
index 0000000..b4b668b
--- /dev/null
+++ b/id/Makefile
@@ -0,0 +1,8 @@
+SHELL := /usr/bin/env bash
+
+REPO_ROOT = $(shell cd .. && pwd)
+
+include $(REPO_ROOT)/scripts/go.mk
+include $(REPO_ROOT)/tools/tools.mk
+include $(REPO_ROOT)/scripts/lib.mk
+
diff --git a/id/README.md b/id/README.md
new file mode 100644
index 0000000..2a92899
--- /dev/null
+++ b/id/README.md
@@ -0,0 +1,7 @@
+# id
+[![ci](https://github.com/ifnotnil/x/actions/workflows/sub_id.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_id.yml)
+[![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/id)](https://goreportcard.com/report/github.com/ifnotnil/x/id)
+[![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/id)](https://pkg.go.dev/github.com/ifnotnil/x/id)
+[![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=id%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/id?tab=versions)
+[![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=id)](https://codecov.io/gh/ifnotnil/x)
+
diff --git a/id/go.mod b/id/go.mod
new file mode 100644
index 0000000..590029b
--- /dev/null
+++ b/id/go.mod
@@ -0,0 +1,14 @@
+module github.com/ifnotnil/x/id
+
+go 1.24.0
+
+require (
+	github.com/ifnotnil/x/tst v0.0.2
+	github.com/stretchr/testify v1.11.1
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
diff --git a/id/go.sum b/id/go.sum
new file mode 100644
index 0000000..eeaccad
--- /dev/null
+++ b/id/go.sum
@@ -0,0 +1,14 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/ifnotnil/x/tst v0.0.2 h1:6ydceMwj3uiKFu1B+TTQJcGd1KZtDOAdyy95kTgtCe4=
+github.com/ifnotnil/x/tst v0.0.2/go.mod h1:TFSDsUOkXhDw6k2+vxuypmPXhJzuQ3U+qWHFc4KiMEo=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
+github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/id/uuid.go b/id/uuid.go
new file mode 100644
index 0000000..a6d3d67
--- /dev/null
+++ b/id/uuid.go
@@ -0,0 +1,77 @@
+package id
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+)
+
+// In URL parameters, the following characters are considered safe and do not need encoding [rfc3986](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.1):
+// Alphabetic characters: A-Z, a-z
+// Digits: 0-9
+// Hyphen: -
+// Underscore: _
+// Period: .
+// Tilde: ~
+
+// Base64 is a [base64.Encoding] based on [base64.URLEncoding] without padding character.
+// alphabet of base64: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
+var (
+	Base64            = base64.URLEncoding.WithPadding(base64.NoPadding)
+	Base64WithPadding = base64.URLEncoding.WithPadding('~')
+)
+
+var (
+	base64UUIDEncodedLen     = Base64.EncodedLen(uuidSize)
+	base64UUIDEncodedLenJSON = base64UUIDEncodedLen + 2
+	zeroUUID                 = [uuidSize]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+)
+
+const uuidSize = 16
+
+type Base64UUID[U ~[uuidSize]byte] struct {
+	Value U
+}
+
+func (u Base64UUID[U]) IsZero() bool {
+	return u.Value == zeroUUID
+}
+
+func (u Base64UUID[U]) MarshalJSON() ([]byte, error) {
+	b := make([]byte, 1, base64UUIDEncodedLenJSON)
+	b[0] = '"'
+	sub := b[1:][:base64UUIDEncodedLen]
+	Base64.Encode(sub, u.Value[:])
+	b = b[0 : base64UUIDEncodedLenJSON-1]
+	b = append(b, '"')
+
+	return b, nil
+}
+
+func (u *Base64UUID[U]) UnmarshalJSON(b []byte) error {
+	var s string
+	err := json.Unmarshal(b, &s)
+	if err != nil {
+		return err
+	}
+
+	decBytes, err := Base64.DecodeString(s)
+	if err != nil {
+		return err
+	}
+
+	if len(decBytes) != uuidSize {
+		return ErrMalformedUUID
+	}
+
+	copy(u.Value[:], decBytes)
+
+	return nil
+}
+
+var ErrMalformedUUID = errors.New("malformed uuid")
+
+var (
+	_ json.Marshaler   = (*Base64UUID[[uuidSize]byte])(nil)
+	_ json.Unmarshaler = (*Base64UUID[[uuidSize]byte])(nil)
+)
diff --git a/id/uuid_test.go b/id/uuid_test.go
new file mode 100644
index 0000000..d1e8a3c
--- /dev/null
+++ b/id/uuid_test.go
@@ -0,0 +1,121 @@
+package id
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/ifnotnil/x/tst"
+	"github.com/stretchr/testify/assert"
+)
+
+type id = [uuidSize]byte
+
+func TestUUID_JSON(t *testing.T) {
+	type Foo struct {
+		ID Base64UUID[id] `json:"id"`
+	}
+
+	type FooPointer struct {
+		ID *Base64UUID[id] `json:"id"`
+	}
+
+	type FooOZ struct {
+		ID Base64UUID[id] `json:"id,omitzero"`
+	}
+
+	type FooPointerOZ struct {
+		ID *Base64UUID[id] `json:"id,omitzero"`
+	}
+
+	const js = `{"id":"AZomiURKfF6MYQcDvjFM_A"}`
+	uuid := id{0x01, 0x9a, 0x26, 0x89, 0x44, 0x4a, 0x7c, 0x5e, 0x8c, 0x61, 0x07, 0x03, 0xbe, 0x31, 0x4c, 0xfc}
+
+	unmarshalTests := []struct {
+		input         string
+		destination   any
+		expected      any
+		errorAsserter tst.ErrorAssertionFunc
+	}{
+		{
+			input:         js,
+			destination:   &Foo{ID: Base64UUID[id]{Value: zeroUUID}},
+			expected:      &Foo{ID: Base64UUID[id]{Value: uuid}},
+			errorAsserter: tst.NoError(),
+		},
+		{
+			input:         js,
+			destination:   &FooPointer{ID: nil},
+			expected:      &FooPointer{ID: &Base64UUID[id]{Value: uuid}},
+			errorAsserter: tst.NoError(),
+		},
+	}
+
+	for i, tc := range unmarshalTests {
+		t.Run(fmt.Sprintf("unmarshal_%d", i), func(t *testing.T) {
+			gotErr := json.Unmarshal([]byte(tc.input), tc.destination)
+			tc.errorAsserter(t, gotErr)
+			assert.Equal(t, tc.expected, tc.destination)
+		})
+	}
+
+	marshalTests := []struct {
+		input         any
+		expectedJSON  string
+		errorAsserter tst.ErrorAssertionFunc
+	}{
+		0: {
+			input:         Foo{ID: Base64UUID[id]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		1: {
+			input:         &Foo{ID: Base64UUID[id]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		2: {
+			input:         FooPointer{ID: &Base64UUID[id]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		3: {
+			input:         &FooPointer{ID: &Base64UUID[id]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		4: {
+			input:         FooOZ{ID: Base64UUID[id]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		5: {
+			input:         &FooOZ{ID: Base64UUID[id]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		6: {
+			input:         FooPointerOZ{ID: &Base64UUID[id]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		7: {
+			input:         &FooPointerOZ{ID: &Base64UUID[id]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		8: {
+			input:         &FooPointerOZ{ID: nil},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+	}
+
+	for i, tc := range marshalTests {
+		t.Run(fmt.Sprintf("marshal_%d", i), func(t *testing.T) {
+			got, gotErr := json.Marshal(tc.input)
+			tc.errorAsserter(t, gotErr)
+			assert.Equal(t, tc.expectedJSON, string(got))
+		})
+	}
+}

From dcecb7e55c8fc7047f95067b9a91c30978a38f3d Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 29 Oct 2025 12:50:00 +0200
Subject: [PATCH 02/15] refactor main readme

---
 README.md | 37 +++++--------------------------------
 1 file changed, 5 insertions(+), 32 deletions(-)

diff --git a/README.md b/README.md
index e773704..81fd797 100644
--- a/README.md
+++ b/README.md
@@ -4,39 +4,12 @@
 https://docs.codecov.com/docs/status-badges
 -->
 
-## http
 
-[Readme](http/README.md) &emsp; &emsp;
-[![ci](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml)
-[![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/http)](https://goreportcard.com/report/github.com/ifnotnil/x/http)
-[![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/http)](https://pkg.go.dev/github.com/ifnotnil/x/http)
-[![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions)
-[![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=http)](https://codecov.io/gh/ifnotnil/x)
 
-Install: `go get -u github.com/ifnotnil/x/http`
+| Module | Description |
+| -------- | ------- |
+| `http` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/http)](https://goreportcard.com/report/github.com/ifnotnil/x/http) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/http)](https://pkg.go.dev/github.com/ifnotnil/x/http) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=http)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/http`<br>[Readme](http/README.md)<br>http middlewares and inbound/outbound loggers |
+| `conf` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/conf)](https://goreportcard.com/report/github.com/ifnotnil/x/conf) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/conf)](https://pkg.go.dev/github.com/ifnotnil/x/conf) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=conf)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/conf`<br>[Readme](conf/README.md)<br>A [knadh/koanf](github.com/knadh/koanf) boilerplate with some helpers |
+| `tst` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/tst)](https://goreportcard.com/report/github.com/ifnotnil/x/tst) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/tst)](https://pkg.go.dev/github.com/ifnotnil/x/tst) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=tst)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/tst`<br>[Readme](tst/README.md)<br>A test helper package providing error assertion test functions. |
 
-## conf
 
-A [knadh/koanf](github.com/knadh/koanf) boilerplate with some helpers.
-
-[Readme](conf/README.md) &emsp; &emsp;
-[![ci](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml)
-[![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/conf)](https://goreportcard.com/report/github.com/ifnotnil/x/conf)
-[![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/conf)](https://pkg.go.dev/github.com/ifnotnil/x/conf)
-[![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=conf%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/conf?tab=versions)
-[![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=conf)](https://codecov.io/gh/ifnotnil/x)
-
-Install: `go get -u github.com/ifnotnil/x/conf`
-
-## tst
-
-A test helper package providing error assertion test functions.
-
-[Readme](tst/README.md) &emsp; &emsp;
-[![ci](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml)
-[![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/tst)](https://goreportcard.com/report/github.com/ifnotnil/x/tst)
-[![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/tst)](https://pkg.go.dev/github.com/ifnotnil/x/tst)
-[![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=tst%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/tst?tab=versions)
-[![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=tst)](https://codecov.io/gh/ifnotnil/x)
-
-Install: `go get -u github.com/ifnotnil/x/tst`

From b2c6d7d8ad2b5c2b11a5a43ca2a857a1cefed3dd Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 29 Oct 2025 12:50:40 +0200
Subject: [PATCH 03/15] refactor main readme

---
 README.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 81fd797..70367b5 100644
--- a/README.md
+++ b/README.md
@@ -8,8 +8,8 @@ https://docs.codecov.com/docs/status-badges
 
 | Module | Description |
 | -------- | ------- |
-| `http` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/http)](https://goreportcard.com/report/github.com/ifnotnil/x/http) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/http)](https://pkg.go.dev/github.com/ifnotnil/x/http) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=http)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/http`<br>[Readme](http/README.md)<br>http middlewares and inbound/outbound loggers |
-| `conf` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/conf)](https://goreportcard.com/report/github.com/ifnotnil/x/conf) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/conf)](https://pkg.go.dev/github.com/ifnotnil/x/conf) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=conf)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/conf`<br>[Readme](conf/README.md)<br>A [knadh/koanf](github.com/knadh/koanf) boilerplate with some helpers |
-| `tst` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/tst)](https://goreportcard.com/report/github.com/ifnotnil/x/tst) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/tst)](https://pkg.go.dev/github.com/ifnotnil/x/tst) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=tst)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/tst`<br>[Readme](tst/README.md)<br>A test helper package providing error assertion test functions. |
+| `http` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/http)](https://goreportcard.com/report/github.com/ifnotnil/x/http) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/http)](https://pkg.go.dev/github.com/ifnotnil/x/http) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=http)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/http`<br><br>[Readme](http/README.md)<br>http middlewares and inbound/outbound loggers |
+| `conf` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/conf)](https://goreportcard.com/report/github.com/ifnotnil/x/conf) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/conf)](https://pkg.go.dev/github.com/ifnotnil/x/conf) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=conf)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/conf`<br><br>[Readme](conf/README.md)<br>A [knadh/koanf](github.com/knadh/koanf) boilerplate with some helpers |
+| `tst` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/tst)](https://goreportcard.com/report/github.com/ifnotnil/x/tst) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/tst)](https://pkg.go.dev/github.com/ifnotnil/x/tst) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=tst)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/tst`<br><br>[Readme](tst/README.md)<br>A test helper package providing error assertion test functions. |
 
 

From 3f6dc1d09813e0814022b6bdfb9acc9586cc3648 Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 29 Oct 2025 12:51:38 +0200
Subject: [PATCH 04/15] refactor main readme

---
 README.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 70367b5..44c1a00 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ https://docs.codecov.com/docs/status-badges
 | Module | Description |
 | -------- | ------- |
 | `http` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/http)](https://goreportcard.com/report/github.com/ifnotnil/x/http) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/http)](https://pkg.go.dev/github.com/ifnotnil/x/http) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=http)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/http`<br><br>[Readme](http/README.md)<br>http middlewares and inbound/outbound loggers |
-| `conf` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/conf)](https://goreportcard.com/report/github.com/ifnotnil/x/conf) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/conf)](https://pkg.go.dev/github.com/ifnotnil/x/conf) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=conf)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/conf`<br><br>[Readme](conf/README.md)<br>A [knadh/koanf](github.com/knadh/koanf) boilerplate with some helpers |
-| `tst` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/tst)](https://goreportcard.com/report/github.com/ifnotnil/x/tst) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/tst)](https://pkg.go.dev/github.com/ifnotnil/x/tst) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=tst)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/tst`<br><br>[Readme](tst/README.md)<br>A test helper package providing error assertion test functions. |
+| `conf` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/conf)](https://goreportcard.com/report/github.com/ifnotnil/x/conf) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/conf)](https://pkg.go.dev/github.com/ifnotnil/x/conf) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=conf%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=conf)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/conf`<br><br>[Readme](conf/README.md)<br>A [knadh/koanf](github.com/knadh/koanf) boilerplate with some helpers |
+| `tst` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/tst)](https://goreportcard.com/report/github.com/ifnotnil/x/tst) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/tst)](https://pkg.go.dev/github.com/ifnotnil/x/tst) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=tst%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=tst)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/tst`<br><br>[Readme](tst/README.md)<br>A test helper package providing error assertion test functions. |
 
 

From 08b3d23e0b582861d81adabaf33fc55059fbb2e2 Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 29 Oct 2025 13:14:05 +0200
Subject: [PATCH 05/15] config

---
 README.md    | 4 ++--
 codecov.yml  | 4 ++++
 tools/gen.go | 5 +++++
 3 files changed, 11 insertions(+), 2 deletions(-)
 create mode 100644 tools/gen.go

diff --git a/README.md b/README.md
index 44c1a00..5d432a6 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ https://docs.codecov.com/docs/status-badges
 | Module | Description |
 | -------- | ------- |
 | `http` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/http)](https://goreportcard.com/report/github.com/ifnotnil/x/http) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/http)](https://pkg.go.dev/github.com/ifnotnil/x/http) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=http)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/http`<br><br>[Readme](http/README.md)<br>http middlewares and inbound/outbound loggers |
-| `conf` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/conf)](https://goreportcard.com/report/github.com/ifnotnil/x/conf) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/conf)](https://pkg.go.dev/github.com/ifnotnil/x/conf) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=conf%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=conf)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/conf`<br><br>[Readme](conf/README.md)<br>A [knadh/koanf](github.com/knadh/koanf) boilerplate with some helpers |
-| `tst` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/tst)](https://goreportcard.com/report/github.com/ifnotnil/x/tst) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/tst)](https://pkg.go.dev/github.com/ifnotnil/x/tst) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=tst%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=tst)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/tst`<br><br>[Readme](tst/README.md)<br>A test helper package providing error assertion test functions. |
+| `conf` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/conf)](https://goreportcard.com/report/github.com/ifnotnil/x/conf) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/conf)](https://pkg.go.dev/github.com/ifnotnil/x/conf) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=conf%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?conf=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=conf)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/conf`<br><br>[Readme](conf/README.md)<br>A [knadh/koanf](github.com/knadh/koanf) boilerplate with some helpers |
+| `tst` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/tst)](https://goreportcard.com/report/github.com/ifnotnil/x/tst) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/tst)](https://pkg.go.dev/github.com/ifnotnil/x/tst) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=tst%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/tst?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=tst)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/tst`<br><br>[Readme](tst/README.md)<br>A test helper package providing error assertion test functions. |
 
 
diff --git a/codecov.yml b/codecov.yml
index f6ba961..67f4cef 100644
--- a/codecov.yml
+++ b/codecov.yml
@@ -34,6 +34,10 @@ component_management:
       name: tst
       paths:
         - "tst/"
+    - component_id: id
+      name: id
+      paths:
+        - "id/"
 
 ignore:
   - "http/internal/testingx" # test helpers
diff --git a/tools/gen.go b/tools/gen.go
new file mode 100644
index 0000000..244eaac
--- /dev/null
+++ b/tools/gen.go
@@ -0,0 +1,5 @@
+//go:build tools
+
+package tools
+
+

From 911853ea9805bd68bc2d78beeee7899ec6c63fc5 Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 29 Oct 2025 13:16:11 +0200
Subject: [PATCH 06/15] readme

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 5d432a6..8996176 100644
--- a/README.md
+++ b/README.md
@@ -11,5 +11,5 @@ https://docs.codecov.com/docs/status-badges
 | `http` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_http.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/http)](https://goreportcard.com/report/github.com/ifnotnil/x/http) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/http)](https://pkg.go.dev/github.com/ifnotnil/x/http) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=http%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=http)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/http`<br><br>[Readme](http/README.md)<br>http middlewares and inbound/outbound loggers |
 | `conf` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_conf.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/conf)](https://goreportcard.com/report/github.com/ifnotnil/x/conf) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/conf)](https://pkg.go.dev/github.com/ifnotnil/x/conf) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=conf%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/http?conf=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=conf)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/conf`<br><br>[Readme](conf/README.md)<br>A [knadh/koanf](github.com/knadh/koanf) boilerplate with some helpers |
 | `tst` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_tst.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/tst)](https://goreportcard.com/report/github.com/ifnotnil/x/tst) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/tst)](https://pkg.go.dev/github.com/ifnotnil/x/tst) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=tst%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/tst?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=tst)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/tst`<br><br>[Readme](tst/README.md)<br>A test helper package providing error assertion test functions. |
-
+| `id` | [![ci](https://github.com/ifnotnil/x/actions/workflows/sub_id.yml/badge.svg)](https://github.com/ifnotnil/x/actions/workflows/sub_id.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ifnotnil/x/id)](https://goreportcard.com/report/github.com/ifnotnil/x/id) [![PkgGoDev](https://pkg.go.dev/badge/github.com/ifnotnit/x/id)](https://pkg.go.dev/github.com/ifnotnil/x/id) [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=id%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/id?tab=versions) [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=id)](https://codecov.io/gh/ifnotnil/x)<br>Install: `go get -u github.com/ifnotnil/x/id`<br><br>[Readme](id/README.md)<br>URL Safe base64 and base 62 wrappers of uuid for text representation. |
 

From 544ab953468e3ec1ef368575ec6ac20db6ea09ca Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 29 Oct 2025 13:18:28 +0200
Subject: [PATCH 07/15] readme

---
 id/README.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/id/README.md b/id/README.md
index 2a92899..03de4df 100644
--- a/id/README.md
+++ b/id/README.md
@@ -5,3 +5,6 @@
 [![Version](https://img.shields.io/github/v/tag/ifnotnil/x?filter=id%2F*)](https://pkg.go.dev/github.com/ifnotnil/x/id?tab=versions)
 [![codecov](https://codecov.io/gh/ifnotnil/x/graph/badge.svg?token=n0t9q5Y3Sf&component=id)](https://codecov.io/gh/ifnotnil/x)
 
+URL Safe base64 and base 62 wrappers of uuid for text representation.
+
+The wrappers work with generics of `~[16]byte` so both `gofrs` and `google` uuid can be wrapped.

From 0a19d5c1787b220a4e459861caa37c984e1dfe95 Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 29 Oct 2025 13:32:02 +0200
Subject: [PATCH 08/15] add encoding.Text* api

---
 id/uuid.go | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/id/uuid.go b/id/uuid.go
index a6d3d67..015117f 100644
--- a/id/uuid.go
+++ b/id/uuid.go
@@ -1,9 +1,11 @@
 package id
 
 import (
+	"encoding"
 	"encoding/base64"
 	"encoding/json"
 	"errors"
+	"slices"
 )
 
 // In URL parameters, the following characters are considered safe and do not need encoding [rfc3986](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.1):
@@ -55,16 +57,33 @@ func (u *Base64UUID[U]) UnmarshalJSON(b []byte) error {
 		return err
 	}
 
-	decBytes, err := Base64.DecodeString(s)
+	return u.UnmarshalText([]byte(s))
+}
+
+func (u Base64UUID[U]) AppendText(b []byte) ([]byte, error) {
+	b = slices.Grow(b, base64UUIDEncodedLen)
+	b = b[:len(b)+base64UUIDEncodedLen]
+	Base64.Encode(b, u.Value[:])
+	return b, nil
+}
+
+func (u Base64UUID[U]) MarshalText() ([]byte, error) {
+	return u.AppendText(nil)
+}
+
+func (u *Base64UUID[U]) UnmarshalText(text []byte) error {
+	dec := [uuidSize]byte{}
+
+	n, err := Base64.Decode(dec[:], text)
 	if err != nil {
 		return err
 	}
 
-	if len(decBytes) != uuidSize {
+	if n != uuidSize {
 		return ErrMalformedUUID
 	}
 
-	copy(u.Value[:], decBytes)
+	u.Value = dec
 
 	return nil
 }
@@ -72,6 +91,9 @@ func (u *Base64UUID[U]) UnmarshalJSON(b []byte) error {
 var ErrMalformedUUID = errors.New("malformed uuid")
 
 var (
-	_ json.Marshaler   = (*Base64UUID[[uuidSize]byte])(nil)
-	_ json.Unmarshaler = (*Base64UUID[[uuidSize]byte])(nil)
+	_ json.Marshaler           = (*Base64UUID[[uuidSize]byte])(nil)
+	_ json.Unmarshaler         = (*Base64UUID[[uuidSize]byte])(nil)
+	_ encoding.TextAppender    = (*Base64UUID[[uuidSize]byte])(nil)
+	_ encoding.TextMarshaler   = (*Base64UUID[[uuidSize]byte])(nil)
+	_ encoding.TextUnmarshaler = (*Base64UUID[[uuidSize]byte])(nil)
 )

From 3f5394b2c478d50e419493dc7135a1c79aa97b3b Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 29 Oct 2025 13:45:52 +0200
Subject: [PATCH 09/15] reuse

---
 id/uuid.go | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/id/uuid.go b/id/uuid.go
index 015117f..b8dd4c2 100644
--- a/id/uuid.go
+++ b/id/uuid.go
@@ -42,9 +42,11 @@ func (u Base64UUID[U]) IsZero() bool {
 func (u Base64UUID[U]) MarshalJSON() ([]byte, error) {
 	b := make([]byte, 1, base64UUIDEncodedLenJSON)
 	b[0] = '"'
-	sub := b[1:][:base64UUIDEncodedLen]
-	Base64.Encode(sub, u.Value[:])
-	b = b[0 : base64UUIDEncodedLenJSON-1]
+	if sub, err := u.AppendText(b[1:]); err != nil {
+		return nil, err
+	} else {
+		b = b[:len(sub)+1]
+	}
 	b = append(b, '"')
 
 	return b, nil

From b7a8cc9045fc5ee22c00ac4b44671a69b73cc0ae Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 29 Oct 2025 13:47:20 +0200
Subject: [PATCH 10/15] comments

---
 id/uuid.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/id/uuid.go b/id/uuid.go
index b8dd4c2..18a4797 100644
--- a/id/uuid.go
+++ b/id/uuid.go
@@ -45,7 +45,7 @@ func (u Base64UUID[U]) MarshalJSON() ([]byte, error) {
 	if sub, err := u.AppendText(b[1:]); err != nil {
 		return nil, err
 	} else {
-		b = b[:len(sub)+1]
+		b = b[:len(sub)+1] // the appended text plus the " character.
 	}
 	b = append(b, '"')
 
@@ -64,7 +64,7 @@ func (u *Base64UUID[U]) UnmarshalJSON(b []byte) error {
 
 func (u Base64UUID[U]) AppendText(b []byte) ([]byte, error) {
 	b = slices.Grow(b, base64UUIDEncodedLen)
-	b = b[:len(b)+base64UUIDEncodedLen]
+	b = b[:len(b)+base64UUIDEncodedLen] // safe since we already grew the buffer.
 	Base64.Encode(b, u.Value[:])
 	return b, nil
 }

From 39ce262ca47271970fa97219db747538208f06bf Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Tue, 11 Nov 2025 22:56:20 +0200
Subject: [PATCH 11/15] dynamic encoding

---
 id/base62.go      |  39 +++++++++++++++
 id/base64.go      |  93 +++++++++++++++++++++++++++++++++++
 id/base64_test.go | 121 ++++++++++++++++++++++++++++++++++++++++++++++
 id/encodings.go   |   1 +
 id/uuid.go        |  99 ++++++++++++++++++-------------------
 id/uuid_test.go   | 120 ---------------------------------------------
 6 files changed, 300 insertions(+), 173 deletions(-)
 create mode 100644 id/base62.go
 create mode 100644 id/base64.go
 create mode 100644 id/base64_test.go
 create mode 100644 id/encodings.go

diff --git a/id/base62.go b/id/base62.go
new file mode 100644
index 0000000..fd377fc
--- /dev/null
+++ b/id/base62.go
@@ -0,0 +1,39 @@
+package id
+
+import (
+	"fmt"
+	"math"
+	"math/big"
+)
+
+type Base62Encoding struct{}
+
+func (e *Base62Encoding) AppendEncode(dst, src []byte) []byte {
+	if len(src) == 0 {
+		return nil
+	}
+
+	num := big.Int{}
+	num.SetBytes(src)
+	return num.Append(dst, 62)
+}
+
+func base62Decode(b []byte) ([]byte, error) {
+	num := big.Int{}
+	n, ok := num.SetString(string(b), 62)
+	if !ok {
+		return nil, fmt.Errorf("tbd")
+	}
+
+	return n.Bytes(), nil
+}
+
+func base62EncodedLen(n int) int {
+	// log2(62) ≈ 5.954196310386875
+	return int(math.Ceil(float64(n) * 8 / 5.954196310386875))
+}
+
+func base62DecodedLen(m int) int {
+	// log2(62) ≈ 5.954196310386875
+	return int(math.Floor(float64(m) * 5.954196310386875 / 8))
+}
diff --git a/id/base64.go b/id/base64.go
new file mode 100644
index 0000000..13b6938
--- /dev/null
+++ b/id/base64.go
@@ -0,0 +1,93 @@
+package id
+
+import (
+	"encoding/base64"
+)
+
+// In URL parameters, the following characters are considered safe and do not need encoding [rfc3986](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.1):
+// Alphabetic characters: A-Z, a-z
+// Digits: 0-9
+// Hyphen: -
+// Underscore: _
+// Period: .
+// Tilde: ~
+
+// stdBase64 is a [base64.Encoding] based on [base64.URLEncoding] without padding character.
+// alphabet of base64: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
+var (
+	stdBase64            = base64.URLEncoding.WithPadding(base64.NoPadding)
+	stdBase64WithPadding = base64.URLEncoding.WithPadding('~')
+)
+
+type Base64 struct{}
+
+func (b Base64) encode(dst, src []byte) {
+	stdBase64.Encode(dst, src)
+}
+
+func (b Base64) appendEncode(dst, src []byte) []byte {
+	return stdBase64.AppendEncode(dst, src)
+}
+
+func (b Base64) encodeToString(src []byte) string {
+	return stdBase64.EncodeToString(src)
+}
+
+func (b Base64) encodedLen(n int) int {
+	return stdBase64.EncodedLen(n)
+}
+
+func (b Base64) appendDecode(dst, src []byte) ([]byte, error) {
+	return stdBase64.AppendDecode(dst, src)
+}
+
+func (b Base64) decodeString(s string) ([]byte, error) {
+	return stdBase64.DecodeString(s)
+}
+
+func (b Base64) decode(dst, src []byte) (n int, err error) {
+	return stdBase64.Decode(dst, src)
+}
+
+func (b Base64) decodedLen(n int) int {
+	return stdBase64.DecodedLen(n)
+}
+
+type Base64WithPadding struct{}
+
+func (b Base64WithPadding) encode(dst, src []byte) {
+	stdBase64WithPadding.Encode(dst, src)
+}
+
+func (b Base64WithPadding) appendEncode(dst, src []byte) []byte {
+	return stdBase64WithPadding.AppendEncode(dst, src)
+}
+
+func (b Base64WithPadding) encodeToString(src []byte) string {
+	return stdBase64WithPadding.EncodeToString(src)
+}
+
+func (b Base64WithPadding) encodedLen(n int) int {
+	return stdBase64WithPadding.EncodedLen(n)
+}
+
+func (b Base64WithPadding) appendDecode(dst, src []byte) ([]byte, error) {
+	return stdBase64WithPadding.AppendDecode(dst, src)
+}
+
+func (b Base64WithPadding) decodeString(s string) ([]byte, error) {
+	return stdBase64WithPadding.DecodeString(s)
+}
+
+func (b Base64WithPadding) decode(dst, src []byte) (n int, err error) {
+	return stdBase64WithPadding.Decode(dst, src)
+}
+
+func (b Base64WithPadding) decodedLen(n int) int {
+	return stdBase64WithPadding.DecodedLen(n)
+}
+
+var (
+	_ Encoding = Base64{}
+	_ Encoding = Base64WithPadding{}
+)
diff --git a/id/base64_test.go b/id/base64_test.go
new file mode 100644
index 0000000..fd7353a
--- /dev/null
+++ b/id/base64_test.go
@@ -0,0 +1,121 @@
+package id
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/ifnotnil/x/tst"
+	"github.com/stretchr/testify/assert"
+)
+
+type id = [uuidSize]byte
+
+func TestUUID_JSON(t *testing.T) {
+	type Foo struct {
+		ID ID[id, Base64] `json:"id"`
+	}
+
+	type FooPointer struct {
+		ID *ID[id, Base64] `json:"id"`
+	}
+
+	type FooOZ struct {
+		ID ID[id, Base64] `json:"id,omitzero"`
+	}
+
+	type FooPointerOZ struct {
+		ID *ID[id, Base64] `json:"id,omitzero"`
+	}
+
+	const js = `{"id":"AZomiURKfF6MYQcDvjFM_A"}`
+	uuid := id{0x01, 0x9a, 0x26, 0x89, 0x44, 0x4a, 0x7c, 0x5e, 0x8c, 0x61, 0x07, 0x03, 0xbe, 0x31, 0x4c, 0xfc}
+
+	unmarshalTests := []struct {
+		input         string
+		destination   any
+		expected      any
+		errorAsserter tst.ErrorAssertionFunc
+	}{
+		{
+			input:         js,
+			destination:   &Foo{ID: ID[id, Base64]{Value: zeroUUID}},
+			expected:      &Foo{ID: ID[id, Base64]{Value: uuid}},
+			errorAsserter: tst.NoError(),
+		},
+		{
+			input:         js,
+			destination:   &FooPointer{ID: nil},
+			expected:      &FooPointer{ID: &ID[id, Base64]{Value: uuid}},
+			errorAsserter: tst.NoError(),
+		},
+	}
+
+	for i, tc := range unmarshalTests {
+		t.Run(fmt.Sprintf("unmarshal_%d", i), func(t *testing.T) {
+			gotErr := json.Unmarshal([]byte(tc.input), tc.destination)
+			tc.errorAsserter(t, gotErr)
+			assert.Equal(t, tc.expected, tc.destination)
+		})
+	}
+
+	marshalTests := []struct {
+		input         any
+		expectedJSON  string
+		errorAsserter tst.ErrorAssertionFunc
+	}{
+		0: {
+			input:         Foo{ID: ID[id, Base64]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		1: {
+			input:         &Foo{ID: ID[id, Base64]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		2: {
+			input:         FooPointer{ID: &ID[id, Base64]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		3: {
+			input:         &FooPointer{ID: &ID[id, Base64]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		4: {
+			input:         FooOZ{ID: ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		5: {
+			input:         &FooOZ{ID: ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		6: {
+			input:         FooPointerOZ{ID: &ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		7: {
+			input:         &FooPointerOZ{ID: &ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		8: {
+			input:         &FooPointerOZ{ID: nil},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+	}
+
+	for i, tc := range marshalTests {
+		t.Run(fmt.Sprintf("marshal_%d", i), func(t *testing.T) {
+			got, gotErr := json.Marshal(tc.input)
+			tc.errorAsserter(t, gotErr)
+			assert.Equal(t, tc.expectedJSON, string(got))
+		})
+	}
+}
diff --git a/id/encodings.go b/id/encodings.go
new file mode 100644
index 0000000..51e9eb9
--- /dev/null
+++ b/id/encodings.go
@@ -0,0 +1 @@
+package id
diff --git a/id/uuid.go b/id/uuid.go
index 18a4797..e37e283 100644
--- a/id/uuid.go
+++ b/id/uuid.go
@@ -2,57 +2,58 @@ package id
 
 import (
 	"encoding"
-	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"slices"
 )
 
-// In URL parameters, the following characters are considered safe and do not need encoding [rfc3986](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.1):
-// Alphabetic characters: A-Z, a-z
-// Digits: 0-9
-// Hyphen: -
-// Underscore: _
-// Period: .
-// Tilde: ~
-
-// Base64 is a [base64.Encoding] based on [base64.URLEncoding] without padding character.
-// alphabet of base64: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
-var (
-	Base64            = base64.URLEncoding.WithPadding(base64.NoPadding)
-	Base64WithPadding = base64.URLEncoding.WithPadding('~')
-)
-
-var (
-	base64UUIDEncodedLen     = Base64.EncodedLen(uuidSize)
-	base64UUIDEncodedLenJSON = base64UUIDEncodedLen + 2
-	zeroUUID                 = [uuidSize]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
-)
-
 const uuidSize = 16
 
-type Base64UUID[U ~[uuidSize]byte] struct {
-	Value U
+type Encoding interface {
+	// encode(dst, src []byte)
+	appendEncode(dst, src []byte) []byte
+	// encodeToString(src []byte) string
+	encodedLen(n int) int
+	// appendDecode(dst, src []byte) ([]byte, error)
+	// decodeString(s string) ([]byte, error)
+	decode(dst, src []byte) (n int, err error)
+	decodedLen(n int) int
 }
 
-func (u Base64UUID[U]) IsZero() bool {
+type ID[UUID ~[uuidSize]byte, Enc Encoding] struct {
+	Value UUID
+}
+
+func (u ID[UUID, Enc]) IsZero() bool {
 	return u.Value == zeroUUID
 }
 
-func (u Base64UUID[U]) MarshalJSON() ([]byte, error) {
-	b := make([]byte, 1, base64UUIDEncodedLenJSON)
+func (u ID[UUID, Enc]) MarshalJSON() ([]byte, error) {
+	var enc Enc
+	ln := enc.encodedLen(uuidSize)
+	b := make([]byte, 1, ln+2)
 	b[0] = '"'
-	if sub, err := u.AppendText(b[1:]); err != nil {
-		return nil, err
-	} else {
-		b = b[:len(sub)+1] // the appended text plus the " character.
-	}
+
+	b = enc.appendEncode(b, u.Value[:])
+
 	b = append(b, '"')
 
 	return b, nil
 }
 
-func (u *Base64UUID[U]) UnmarshalJSON(b []byte) error {
+func (u ID[UUID, Enc]) AppendText(b []byte) ([]byte, error) {
+	var enc Enc
+	ln := enc.encodedLen(uuidSize)
+
+	b = slices.Grow(b, ln)
+	return enc.appendEncode(b, u.Value[:]), nil
+}
+
+func (u ID[UUID, Enc]) MarshalText() ([]byte, error) {
+	return u.AppendText(nil)
+}
+
+func (u *ID[UUID, Enc]) UnmarshalJSON(b []byte) error {
 	var s string
 	err := json.Unmarshal(b, &s)
 	if err != nil {
@@ -62,21 +63,11 @@ func (u *Base64UUID[U]) UnmarshalJSON(b []byte) error {
 	return u.UnmarshalText([]byte(s))
 }
 
-func (u Base64UUID[U]) AppendText(b []byte) ([]byte, error) {
-	b = slices.Grow(b, base64UUIDEncodedLen)
-	b = b[:len(b)+base64UUIDEncodedLen] // safe since we already grew the buffer.
-	Base64.Encode(b, u.Value[:])
-	return b, nil
-}
-
-func (u Base64UUID[U]) MarshalText() ([]byte, error) {
-	return u.AppendText(nil)
-}
-
-func (u *Base64UUID[U]) UnmarshalText(text []byte) error {
+func (u *ID[UUID, Enc]) UnmarshalText(text []byte) error {
+	var enc Enc
 	dec := [uuidSize]byte{}
 
-	n, err := Base64.Decode(dec[:], text)
+	n, err := enc.decode(dec[:], text)
 	if err != nil {
 		return err
 	}
@@ -90,12 +81,14 @@ func (u *Base64UUID[U]) UnmarshalText(text []byte) error {
 	return nil
 }
 
-var ErrMalformedUUID = errors.New("malformed uuid")
-
 var (
-	_ json.Marshaler           = (*Base64UUID[[uuidSize]byte])(nil)
-	_ json.Unmarshaler         = (*Base64UUID[[uuidSize]byte])(nil)
-	_ encoding.TextAppender    = (*Base64UUID[[uuidSize]byte])(nil)
-	_ encoding.TextMarshaler   = (*Base64UUID[[uuidSize]byte])(nil)
-	_ encoding.TextUnmarshaler = (*Base64UUID[[uuidSize]byte])(nil)
+	_ json.Marshaler           = (*ID[[uuidSize]byte, Base64])(nil)
+	_ json.Unmarshaler         = (*ID[[uuidSize]byte, Base64])(nil)
+	_ encoding.TextAppender    = (*ID[[uuidSize]byte, Base64])(nil)
+	_ encoding.TextMarshaler   = (*ID[[uuidSize]byte, Base64])(nil)
+	_ encoding.TextUnmarshaler = (*ID[[uuidSize]byte, Base64])(nil)
 )
+
+var ErrMalformedUUID = errors.New("malformed uuid")
+
+var zeroUUID = [uuidSize]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
diff --git a/id/uuid_test.go b/id/uuid_test.go
index d1e8a3c..51e9eb9 100644
--- a/id/uuid_test.go
+++ b/id/uuid_test.go
@@ -1,121 +1 @@
 package id
-
-import (
-	"encoding/json"
-	"fmt"
-	"testing"
-
-	"github.com/ifnotnil/x/tst"
-	"github.com/stretchr/testify/assert"
-)
-
-type id = [uuidSize]byte
-
-func TestUUID_JSON(t *testing.T) {
-	type Foo struct {
-		ID Base64UUID[id] `json:"id"`
-	}
-
-	type FooPointer struct {
-		ID *Base64UUID[id] `json:"id"`
-	}
-
-	type FooOZ struct {
-		ID Base64UUID[id] `json:"id,omitzero"`
-	}
-
-	type FooPointerOZ struct {
-		ID *Base64UUID[id] `json:"id,omitzero"`
-	}
-
-	const js = `{"id":"AZomiURKfF6MYQcDvjFM_A"}`
-	uuid := id{0x01, 0x9a, 0x26, 0x89, 0x44, 0x4a, 0x7c, 0x5e, 0x8c, 0x61, 0x07, 0x03, 0xbe, 0x31, 0x4c, 0xfc}
-
-	unmarshalTests := []struct {
-		input         string
-		destination   any
-		expected      any
-		errorAsserter tst.ErrorAssertionFunc
-	}{
-		{
-			input:         js,
-			destination:   &Foo{ID: Base64UUID[id]{Value: zeroUUID}},
-			expected:      &Foo{ID: Base64UUID[id]{Value: uuid}},
-			errorAsserter: tst.NoError(),
-		},
-		{
-			input:         js,
-			destination:   &FooPointer{ID: nil},
-			expected:      &FooPointer{ID: &Base64UUID[id]{Value: uuid}},
-			errorAsserter: tst.NoError(),
-		},
-	}
-
-	for i, tc := range unmarshalTests {
-		t.Run(fmt.Sprintf("unmarshal_%d", i), func(t *testing.T) {
-			gotErr := json.Unmarshal([]byte(tc.input), tc.destination)
-			tc.errorAsserter(t, gotErr)
-			assert.Equal(t, tc.expected, tc.destination)
-		})
-	}
-
-	marshalTests := []struct {
-		input         any
-		expectedJSON  string
-		errorAsserter tst.ErrorAssertionFunc
-	}{
-		0: {
-			input:         Foo{ID: Base64UUID[id]{Value: uuid}},
-			expectedJSON:  js,
-			errorAsserter: tst.NoError(),
-		},
-		1: {
-			input:         &Foo{ID: Base64UUID[id]{Value: uuid}},
-			expectedJSON:  js,
-			errorAsserter: tst.NoError(),
-		},
-		2: {
-			input:         FooPointer{ID: &Base64UUID[id]{Value: uuid}},
-			expectedJSON:  js,
-			errorAsserter: tst.NoError(),
-		},
-		3: {
-			input:         &FooPointer{ID: &Base64UUID[id]{Value: uuid}},
-			expectedJSON:  js,
-			errorAsserter: tst.NoError(),
-		},
-		4: {
-			input:         FooOZ{ID: Base64UUID[id]{Value: zeroUUID}},
-			expectedJSON:  `{}`,
-			errorAsserter: tst.NoError(),
-		},
-		5: {
-			input:         &FooOZ{ID: Base64UUID[id]{Value: zeroUUID}},
-			expectedJSON:  `{}`,
-			errorAsserter: tst.NoError(),
-		},
-		6: {
-			input:         FooPointerOZ{ID: &Base64UUID[id]{Value: zeroUUID}},
-			expectedJSON:  `{}`,
-			errorAsserter: tst.NoError(),
-		},
-		7: {
-			input:         &FooPointerOZ{ID: &Base64UUID[id]{Value: zeroUUID}},
-			expectedJSON:  `{}`,
-			errorAsserter: tst.NoError(),
-		},
-		8: {
-			input:         &FooPointerOZ{ID: nil},
-			expectedJSON:  `{}`,
-			errorAsserter: tst.NoError(),
-		},
-	}
-
-	for i, tc := range marshalTests {
-		t.Run(fmt.Sprintf("marshal_%d", i), func(t *testing.T) {
-			got, gotErr := json.Marshal(tc.input)
-			tc.errorAsserter(t, gotErr)
-			assert.Equal(t, tc.expectedJSON, string(got))
-		})
-	}
-}

From 7d9439c63cf11553baf1470d0b53a52fe16ea7c8 Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Wed, 19 Nov 2025 21:27:30 +0200
Subject: [PATCH 12/15] move tests

---
 id/base64_test.go | 121 -----------------------------------------
 id/uuid.go        |  10 ++--
 id/uuid_test.go   | 133 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 136 insertions(+), 128 deletions(-)
 delete mode 100644 id/base64_test.go

diff --git a/id/base64_test.go b/id/base64_test.go
deleted file mode 100644
index fd7353a..0000000
--- a/id/base64_test.go
+++ /dev/null
@@ -1,121 +0,0 @@
-package id
-
-import (
-	"encoding/json"
-	"fmt"
-	"testing"
-
-	"github.com/ifnotnil/x/tst"
-	"github.com/stretchr/testify/assert"
-)
-
-type id = [uuidSize]byte
-
-func TestUUID_JSON(t *testing.T) {
-	type Foo struct {
-		ID ID[id, Base64] `json:"id"`
-	}
-
-	type FooPointer struct {
-		ID *ID[id, Base64] `json:"id"`
-	}
-
-	type FooOZ struct {
-		ID ID[id, Base64] `json:"id,omitzero"`
-	}
-
-	type FooPointerOZ struct {
-		ID *ID[id, Base64] `json:"id,omitzero"`
-	}
-
-	const js = `{"id":"AZomiURKfF6MYQcDvjFM_A"}`
-	uuid := id{0x01, 0x9a, 0x26, 0x89, 0x44, 0x4a, 0x7c, 0x5e, 0x8c, 0x61, 0x07, 0x03, 0xbe, 0x31, 0x4c, 0xfc}
-
-	unmarshalTests := []struct {
-		input         string
-		destination   any
-		expected      any
-		errorAsserter tst.ErrorAssertionFunc
-	}{
-		{
-			input:         js,
-			destination:   &Foo{ID: ID[id, Base64]{Value: zeroUUID}},
-			expected:      &Foo{ID: ID[id, Base64]{Value: uuid}},
-			errorAsserter: tst.NoError(),
-		},
-		{
-			input:         js,
-			destination:   &FooPointer{ID: nil},
-			expected:      &FooPointer{ID: &ID[id, Base64]{Value: uuid}},
-			errorAsserter: tst.NoError(),
-		},
-	}
-
-	for i, tc := range unmarshalTests {
-		t.Run(fmt.Sprintf("unmarshal_%d", i), func(t *testing.T) {
-			gotErr := json.Unmarshal([]byte(tc.input), tc.destination)
-			tc.errorAsserter(t, gotErr)
-			assert.Equal(t, tc.expected, tc.destination)
-		})
-	}
-
-	marshalTests := []struct {
-		input         any
-		expectedJSON  string
-		errorAsserter tst.ErrorAssertionFunc
-	}{
-		0: {
-			input:         Foo{ID: ID[id, Base64]{Value: uuid}},
-			expectedJSON:  js,
-			errorAsserter: tst.NoError(),
-		},
-		1: {
-			input:         &Foo{ID: ID[id, Base64]{Value: uuid}},
-			expectedJSON:  js,
-			errorAsserter: tst.NoError(),
-		},
-		2: {
-			input:         FooPointer{ID: &ID[id, Base64]{Value: uuid}},
-			expectedJSON:  js,
-			errorAsserter: tst.NoError(),
-		},
-		3: {
-			input:         &FooPointer{ID: &ID[id, Base64]{Value: uuid}},
-			expectedJSON:  js,
-			errorAsserter: tst.NoError(),
-		},
-		4: {
-			input:         FooOZ{ID: ID[id, Base64]{Value: zeroUUID}},
-			expectedJSON:  `{}`,
-			errorAsserter: tst.NoError(),
-		},
-		5: {
-			input:         &FooOZ{ID: ID[id, Base64]{Value: zeroUUID}},
-			expectedJSON:  `{}`,
-			errorAsserter: tst.NoError(),
-		},
-		6: {
-			input:         FooPointerOZ{ID: &ID[id, Base64]{Value: zeroUUID}},
-			expectedJSON:  `{}`,
-			errorAsserter: tst.NoError(),
-		},
-		7: {
-			input:         &FooPointerOZ{ID: &ID[id, Base64]{Value: zeroUUID}},
-			expectedJSON:  `{}`,
-			errorAsserter: tst.NoError(),
-		},
-		8: {
-			input:         &FooPointerOZ{ID: nil},
-			expectedJSON:  `{}`,
-			errorAsserter: tst.NoError(),
-		},
-	}
-
-	for i, tc := range marshalTests {
-		t.Run(fmt.Sprintf("marshal_%d", i), func(t *testing.T) {
-			got, gotErr := json.Marshal(tc.input)
-			tc.errorAsserter(t, gotErr)
-			assert.Equal(t, tc.expectedJSON, string(got))
-		})
-	}
-}
diff --git a/id/uuid.go b/id/uuid.go
index e37e283..37576d3 100644
--- a/id/uuid.go
+++ b/id/uuid.go
@@ -4,13 +4,12 @@ import (
 	"encoding"
 	"encoding/json"
 	"errors"
-	"slices"
 )
 
 const uuidSize = 16
 
 type Encoding interface {
-	// encode(dst, src []byte)
+	encode(dst, src []byte)
 	appendEncode(dst, src []byte) []byte
 	// encodeToString(src []byte) string
 	encodedLen(n int) int
@@ -31,8 +30,8 @@ func (u ID[UUID, Enc]) IsZero() bool {
 func (u ID[UUID, Enc]) MarshalJSON() ([]byte, error) {
 	var enc Enc
 	ln := enc.encodedLen(uuidSize)
-	b := make([]byte, 1, ln+2)
-	b[0] = '"'
+	b := make([]byte, 0, ln+2)
+	b = append(b, '"')
 
 	b = enc.appendEncode(b, u.Value[:])
 
@@ -43,9 +42,6 @@ func (u ID[UUID, Enc]) MarshalJSON() ([]byte, error) {
 
 func (u ID[UUID, Enc]) AppendText(b []byte) ([]byte, error) {
 	var enc Enc
-	ln := enc.encodedLen(uuidSize)
-
-	b = slices.Grow(b, ln)
 	return enc.appendEncode(b, u.Value[:]), nil
 }
 
diff --git a/id/uuid_test.go b/id/uuid_test.go
index 51e9eb9..d48ad29 100644
--- a/id/uuid_test.go
+++ b/id/uuid_test.go
@@ -1 +1,134 @@
 package id
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/ifnotnil/x/tst"
+	"github.com/stretchr/testify/assert"
+)
+
+type id = [uuidSize]byte
+
+func TestJSONUnmarshal(t *testing.T) {
+	type Foo struct {
+		ID ID[id, Base64] `json:"id"`
+	}
+
+	type FooPointer struct {
+		ID *ID[id, Base64] `json:"id"`
+	}
+
+	const js = `{"id":"AZomiURKfF6MYQcDvjFM_A"}`
+	uuid := id{0x01, 0x9a, 0x26, 0x89, 0x44, 0x4a, 0x7c, 0x5e, 0x8c, 0x61, 0x07, 0x03, 0xbe, 0x31, 0x4c, 0xfc}
+
+	unmarshalTests := []struct {
+		input         string
+		destination   any
+		expected      any
+		errorAsserter tst.ErrorAssertionFunc
+	}{
+		{
+			input:         js,
+			destination:   &Foo{ID: ID[id, Base64]{Value: zeroUUID}},
+			expected:      &Foo{ID: ID[id, Base64]{Value: uuid}},
+			errorAsserter: tst.NoError(),
+		},
+		{
+			input:         js,
+			destination:   &FooPointer{ID: nil},
+			expected:      &FooPointer{ID: &ID[id, Base64]{Value: uuid}},
+			errorAsserter: tst.NoError(),
+		},
+	}
+
+	for i, tc := range unmarshalTests {
+		t.Run(fmt.Sprintf("unmarshal_%d", i), func(t *testing.T) {
+			gotErr := json.Unmarshal([]byte(tc.input), tc.destination)
+			tc.errorAsserter(t, gotErr)
+			assert.Equal(t, tc.expected, tc.destination)
+		})
+	}
+}
+
+func TestJSONMarshal(t *testing.T) {
+	type Foo struct {
+		ID ID[id, Base64] `json:"id"`
+	}
+
+	type FooPointer struct {
+		ID *ID[id, Base64] `json:"id"`
+	}
+
+	type FooOZ struct {
+		ID ID[id, Base64] `json:"id,omitzero"`
+	}
+
+	type FooPointerOZ struct {
+		ID *ID[id, Base64] `json:"id,omitzero"`
+	}
+
+	const js = `{"id":"AZomiURKfF6MYQcDvjFM_A"}`
+	uuid := id{0x01, 0x9a, 0x26, 0x89, 0x44, 0x4a, 0x7c, 0x5e, 0x8c, 0x61, 0x07, 0x03, 0xbe, 0x31, 0x4c, 0xfc}
+
+	marshalTests := []struct {
+		input         any
+		expectedJSON  string
+		errorAsserter tst.ErrorAssertionFunc
+	}{
+		0: {
+			input:         Foo{ID: ID[id, Base64]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		1: {
+			input:         &Foo{ID: ID[id, Base64]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		2: {
+			input:         FooPointer{ID: &ID[id, Base64]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		3: {
+			input:         &FooPointer{ID: &ID[id, Base64]{Value: uuid}},
+			expectedJSON:  js,
+			errorAsserter: tst.NoError(),
+		},
+		4: {
+			input:         FooOZ{ID: ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		5: {
+			input:         &FooOZ{ID: ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		6: {
+			input:         FooPointerOZ{ID: &ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		7: {
+			input:         &FooPointerOZ{ID: &ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+		8: {
+			input:         &FooPointerOZ{ID: nil},
+			expectedJSON:  `{}`,
+			errorAsserter: tst.NoError(),
+		},
+	}
+
+	for i, tc := range marshalTests {
+		t.Run(fmt.Sprintf("marshal_%d", i), func(t *testing.T) {
+			got, gotErr := json.Marshal(tc.input)
+			tc.errorAsserter(t, gotErr)
+			assert.Equal(t, tc.expectedJSON, string(got))
+		})
+	}
+}

From 35f29bd4315e9eccf0ee8fb36d27da9e26faf11c Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Thu, 20 Nov 2025 19:11:39 +0200
Subject: [PATCH 13/15] tests

---
 id/base64.go    |   4 +-
 id/encodings.go |   1 -
 id/uuid.go      |  16 ++---
 id/uuid_test.go | 183 ++++++++++++++++++++++++++++++------------------
 4 files changed, 124 insertions(+), 80 deletions(-)
 delete mode 100644 id/encodings.go

diff --git a/id/base64.go b/id/base64.go
index 13b6938..1fcf1f6 100644
--- a/id/base64.go
+++ b/id/base64.go
@@ -88,6 +88,6 @@ func (b Base64WithPadding) decodedLen(n int) int {
 }
 
 var (
-	_ Encoding = Base64{}
-	_ Encoding = Base64WithPadding{}
+	_ encoding = Base64{}
+	_ encoding = Base64WithPadding{}
 )
diff --git a/id/encodings.go b/id/encodings.go
deleted file mode 100644
index 51e9eb9..0000000
--- a/id/encodings.go
+++ /dev/null
@@ -1 +0,0 @@
-package id
diff --git a/id/uuid.go b/id/uuid.go
index 37576d3..5142485 100644
--- a/id/uuid.go
+++ b/id/uuid.go
@@ -1,14 +1,14 @@
 package id
 
 import (
-	"encoding"
+	eng "encoding"
 	"encoding/json"
 	"errors"
 )
 
 const uuidSize = 16
 
-type Encoding interface {
+type encoding interface {
 	encode(dst, src []byte)
 	appendEncode(dst, src []byte) []byte
 	// encodeToString(src []byte) string
@@ -19,7 +19,7 @@ type Encoding interface {
 	decodedLen(n int) int
 }
 
-type ID[UUID ~[uuidSize]byte, Enc Encoding] struct {
+type ID[UUID ~[uuidSize]byte, Enc encoding] struct {
 	Value UUID
 }
 
@@ -78,11 +78,11 @@ func (u *ID[UUID, Enc]) UnmarshalText(text []byte) error {
 }
 
 var (
-	_ json.Marshaler           = (*ID[[uuidSize]byte, Base64])(nil)
-	_ json.Unmarshaler         = (*ID[[uuidSize]byte, Base64])(nil)
-	_ encoding.TextAppender    = (*ID[[uuidSize]byte, Base64])(nil)
-	_ encoding.TextMarshaler   = (*ID[[uuidSize]byte, Base64])(nil)
-	_ encoding.TextUnmarshaler = (*ID[[uuidSize]byte, Base64])(nil)
+	_ json.Marshaler      = (*ID[[uuidSize]byte, Base64])(nil)
+	_ eng.TextAppender    = (*ID[[uuidSize]byte, Base64])(nil)
+	_ eng.TextMarshaler   = (*ID[[uuidSize]byte, Base64])(nil)
+	_ json.Unmarshaler    = (*ID[[uuidSize]byte, Base64])(nil)
+	_ eng.TextUnmarshaler = (*ID[[uuidSize]byte, Base64])(nil)
 )
 
 var ErrMalformedUUID = errors.New("malformed uuid")
diff --git a/id/uuid_test.go b/id/uuid_test.go
index d48ad29..ac5c8d5 100644
--- a/id/uuid_test.go
+++ b/id/uuid_test.go
@@ -2,7 +2,6 @@ package id
 
 import (
 	"encoding/json"
-	"fmt"
 	"testing"
 
 	"github.com/ifnotnil/x/tst"
@@ -11,124 +10,170 @@ import (
 
 type id = [uuidSize]byte
 
+type unmarshalTest struct {
+	name          string
+	input         string
+	destination   any
+	expected      any
+	errorAsserter tst.ErrorAssertionFunc
+}
+
+func (tc unmarshalTest) Test(t *testing.T) {
+	gotErr := json.Unmarshal([]byte(tc.input), tc.destination)
+	tc.errorAsserter(t, gotErr)
+	assert.Equal(t, tc.expected, tc.destination)
+}
+
 func TestJSONUnmarshal(t *testing.T) {
-	type Foo struct {
-		ID ID[id, Base64] `json:"id"`
+	type Foo[Enc encoding] struct {
+		ID ID[id, Enc] `json:"id"`
 	}
 
-	type FooPointer struct {
-		ID *ID[id, Base64] `json:"id"`
+	type FooPointer[Enc encoding] struct {
+		ID *ID[id, Enc] `json:"id"`
 	}
 
-	const js = `{"id":"AZomiURKfF6MYQcDvjFM_A"}`
 	uuid := id{0x01, 0x9a, 0x26, 0x89, 0x44, 0x4a, 0x7c, 0x5e, 0x8c, 0x61, 0x07, 0x03, 0xbe, 0x31, 0x4c, 0xfc}
 
-	unmarshalTests := []struct {
-		input         string
-		destination   any
-		expected      any
-		errorAsserter tst.ErrorAssertionFunc
-	}{
+	unmarshalTests := []unmarshalTest{
+		{
+			name:          "Foo[Base64]",
+			input:         `{"id":"AZomiURKfF6MYQcDvjFM_A"}`,
+			destination:   &Foo[Base64]{ID: ID[id, Base64]{Value: zeroUUID}},
+			expected:      &Foo[Base64]{ID: ID[id, Base64]{Value: uuid}},
+			errorAsserter: tst.NoError(),
+		},
+		{
+			name:          "FooPointer[Base64]",
+			input:         `{"id":"AZomiURKfF6MYQcDvjFM_A"}`,
+			destination:   &FooPointer[Base64]{ID: nil},
+			expected:      &FooPointer[Base64]{ID: &ID[id, Base64]{Value: uuid}},
+			errorAsserter: tst.NoError(),
+		},
 		{
-			input:         js,
-			destination:   &Foo{ID: ID[id, Base64]{Value: zeroUUID}},
-			expected:      &Foo{ID: ID[id, Base64]{Value: uuid}},
+			name:          "Foo[Base64WithPadding]",
+			input:         `{"id":"AZomiURKfF6MYQcDvjFM_A~~"}`,
+			destination:   &Foo[Base64WithPadding]{ID: ID[id, Base64WithPadding]{Value: zeroUUID}},
+			expected:      &Foo[Base64WithPadding]{ID: ID[id, Base64WithPadding]{Value: uuid}},
 			errorAsserter: tst.NoError(),
 		},
 		{
-			input:         js,
-			destination:   &FooPointer{ID: nil},
-			expected:      &FooPointer{ID: &ID[id, Base64]{Value: uuid}},
+			name:          "FooPointer[Base64WithPadding]",
+			input:         `{"id":"AZomiURKfF6MYQcDvjFM_A~~"}`,
+			destination:   &FooPointer[Base64WithPadding]{ID: nil},
+			expected:      &FooPointer[Base64WithPadding]{ID: &ID[id, Base64WithPadding]{Value: uuid}},
 			errorAsserter: tst.NoError(),
 		},
 	}
 
-	for i, tc := range unmarshalTests {
-		t.Run(fmt.Sprintf("unmarshal_%d", i), func(t *testing.T) {
-			gotErr := json.Unmarshal([]byte(tc.input), tc.destination)
-			tc.errorAsserter(t, gotErr)
-			assert.Equal(t, tc.expected, tc.destination)
-		})
+	for _, tc := range unmarshalTests {
+		t.Run(tc.name, tc.Test)
 	}
 }
 
+type marshalTestCase struct {
+	name          string
+	input         any
+	expectedJSON  string
+	errorAsserter tst.ErrorAssertionFunc
+}
+
+func (tc marshalTestCase) Test(t *testing.T) {
+	got, gotErr := json.Marshal(tc.input)
+	tc.errorAsserter(t, gotErr)
+	assert.Equal(t, tc.expectedJSON, string(got))
+}
+
 func TestJSONMarshal(t *testing.T) {
-	type Foo struct {
-		ID ID[id, Base64] `json:"id"`
+	type Foo[enc encoding] struct {
+		ID ID[id, enc] `json:"id"`
 	}
 
-	type FooPointer struct {
-		ID *ID[id, Base64] `json:"id"`
+	type FooPointer[enc encoding] struct {
+		ID *ID[id, enc] `json:"id"`
 	}
 
-	type FooOZ struct {
-		ID ID[id, Base64] `json:"id,omitzero"`
+	type FooOZ[enc encoding] struct {
+		ID ID[id, enc] `json:"id,omitzero"`
 	}
 
-	type FooPointerOZ struct {
-		ID *ID[id, Base64] `json:"id,omitzero"`
+	type FooPointerOZ[enc encoding] struct {
+		ID *ID[id, enc] `json:"id,omitzero"`
 	}
 
-	const js = `{"id":"AZomiURKfF6MYQcDvjFM_A"}`
+	const jsBase64 = `{"id":"AZomiURKfF6MYQcDvjFM_A"}`
 	uuid := id{0x01, 0x9a, 0x26, 0x89, 0x44, 0x4a, 0x7c, 0x5e, 0x8c, 0x61, 0x07, 0x03, 0xbe, 0x31, 0x4c, 0xfc}
 
-	marshalTests := []struct {
-		input         any
-		expectedJSON  string
-		errorAsserter tst.ErrorAssertionFunc
-	}{
-		0: {
-			input:         Foo{ID: ID[id, Base64]{Value: uuid}},
-			expectedJSON:  js,
+	marshalTests := []marshalTestCase{
+		{
+			name:          "FooOZ[Base64] zero",
+			input:         FooOZ[Base64]{ID: ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
 			errorAsserter: tst.NoError(),
 		},
-		1: {
-			input:         &Foo{ID: ID[id, Base64]{Value: uuid}},
-			expectedJSON:  js,
+		{
+			name:          "*FooOZ[Base64] zero",
+			input:         &FooOZ[Base64]{ID: ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
 			errorAsserter: tst.NoError(),
 		},
-		2: {
-			input:         FooPointer{ID: &ID[id, Base64]{Value: uuid}},
-			expectedJSON:  js,
+		{
+			name:          "FooPointerOZ[Base64] zero",
+			input:         FooPointerOZ[Base64]{ID: &ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
 			errorAsserter: tst.NoError(),
 		},
-		3: {
-			input:         &FooPointer{ID: &ID[id, Base64]{Value: uuid}},
-			expectedJSON:  js,
+		{
+			name:          "*FooPointerOZ[Base64] zero",
+			input:         &FooPointerOZ[Base64]{ID: &ID[id, Base64]{Value: zeroUUID}},
+			expectedJSON:  `{}`,
 			errorAsserter: tst.NoError(),
 		},
-		4: {
-			input:         FooOZ{ID: ID[id, Base64]{Value: zeroUUID}},
+		{
+			name:          "FooPointerOZ[Base64] nil",
+			input:         FooPointerOZ[Base64]{ID: nil},
 			expectedJSON:  `{}`,
 			errorAsserter: tst.NoError(),
 		},
-		5: {
-			input:         &FooOZ{ID: ID[id, Base64]{Value: zeroUUID}},
+		{
+			name:          "*FooPointerOZ[Base64] nil",
+			input:         &FooPointerOZ[Base64]{ID: nil},
 			expectedJSON:  `{}`,
 			errorAsserter: tst.NoError(),
 		},
-		6: {
-			input:         FooPointerOZ{ID: &ID[id, Base64]{Value: zeroUUID}},
-			expectedJSON:  `{}`,
+		{
+			name:          "Foo[Base64] uuid",
+			input:         Foo[Base64]{ID: ID[id, Base64]{Value: uuid}},
+			expectedJSON:  jsBase64,
 			errorAsserter: tst.NoError(),
 		},
-		7: {
-			input:         &FooPointerOZ{ID: &ID[id, Base64]{Value: zeroUUID}},
-			expectedJSON:  `{}`,
+		{
+			name:          "*Foo[Base64] uuid",
+			input:         &Foo[Base64]{ID: ID[id, Base64]{Value: uuid}},
+			expectedJSON:  jsBase64,
 			errorAsserter: tst.NoError(),
 		},
-		8: {
-			input:         &FooPointerOZ{ID: nil},
-			expectedJSON:  `{}`,
+		{
+			name:          "FooPointerOZ[Base64] uuid",
+			input:         FooPointerOZ[Base64]{ID: &ID[id, Base64]{Value: uuid}},
+			expectedJSON:  jsBase64,
+			errorAsserter: tst.NoError(),
+		},
+		{
+			name:          "*FooPointerOZ[Base64] uuid",
+			input:         &FooPointerOZ[Base64]{ID: &ID[id, Base64]{Value: uuid}},
+			expectedJSON:  jsBase64,
+			errorAsserter: tst.NoError(),
+		},
+		{
+			name:          "Foo[Base64WithPadding] uuid",
+			input:         Foo[Base64WithPadding]{ID: ID[id, Base64WithPadding]{Value: uuid}},
+			expectedJSON:  `{"id":"AZomiURKfF6MYQcDvjFM_A~~"}`,
 			errorAsserter: tst.NoError(),
 		},
 	}
 
-	for i, tc := range marshalTests {
-		t.Run(fmt.Sprintf("marshal_%d", i), func(t *testing.T) {
-			got, gotErr := json.Marshal(tc.input)
-			tc.errorAsserter(t, gotErr)
-			assert.Equal(t, tc.expectedJSON, string(got))
-		})
+	for _, tc := range marshalTests {
+		t.Run(tc.name, tc.Test)
 	}
 }

From 377dc3e4ace3453affe6447dd2077f343bd823e5 Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Sun, 23 Nov 2025 11:19:03 +0200
Subject: [PATCH 14/15] base 62

---
 id/base62.go    | 36 ++++++++++++++++++++++++++----------
 id/uuid.go      |  4 ++--
 id/uuid_test.go | 20 ++++++++++++++++++++
 3 files changed, 48 insertions(+), 12 deletions(-)

diff --git a/id/base62.go b/id/base62.go
index fd377fc..ef4a952 100644
--- a/id/base62.go
+++ b/id/base62.go
@@ -6,9 +6,9 @@ import (
 	"math/big"
 )
 
-type Base62Encoding struct{}
+type Base62 struct{}
 
-func (e *Base62Encoding) AppendEncode(dst, src []byte) []byte {
+func (e Base62) appendEncode(dst, src []byte) []byte {
 	if len(src) == 0 {
 		return nil
 	}
@@ -18,22 +18,38 @@ func (e *Base62Encoding) AppendEncode(dst, src []byte) []byte {
 	return num.Append(dst, 62)
 }
 
-func base62Decode(b []byte) ([]byte, error) {
+func (e Base62) encodedLen(n int) int {
+	return base62EncodedLen(n)
+}
+
+func (e Base62) decode(dst, src []byte) (n int, err error) {
+	if len(src) == 0 {
+		return 0, nil
+	}
+
 	num := big.Int{}
-	n, ok := num.SetString(string(b), 62)
+	nn, ok := num.SetString(string(src), 62)
 	if !ok {
-		return nil, fmt.Errorf("tbd")
+		return 0, fmt.Errorf("base62 error while parsing")
 	}
 
-	return n.Bytes(), nil
+	bb := nn.Bytes()
+	// if len(bb) != uuidSize {
+	// 	return 0, fmt.Errorf("base62 error while parsing")
+	// }
+
+	return copy(dst, bb), nil
 }
 
+// lg262 : log2(62) ≈ 5.954196310386875
+const lg262 = 5.954196310386875
+
 func base62EncodedLen(n int) int {
-	// log2(62) ≈ 5.954196310386875
-	return int(math.Ceil(float64(n) * 8 / 5.954196310386875))
+	return int(math.Ceil(float64(n) * 8 / lg262))
 }
 
 func base62DecodedLen(m int) int {
-	// log2(62) ≈ 5.954196310386875
-	return int(math.Floor(float64(m) * 5.954196310386875 / 8))
+	return int(math.Floor(float64(m) * lg262 / 8))
 }
+
+var _ encoding = Base62{}
diff --git a/id/uuid.go b/id/uuid.go
index 5142485..967723f 100644
--- a/id/uuid.go
+++ b/id/uuid.go
@@ -9,14 +9,14 @@ import (
 const uuidSize = 16
 
 type encoding interface {
-	encode(dst, src []byte)
+	// encode(dst, src []byte)
 	appendEncode(dst, src []byte) []byte
 	// encodeToString(src []byte) string
 	encodedLen(n int) int
 	// appendDecode(dst, src []byte) ([]byte, error)
 	// decodeString(s string) ([]byte, error)
 	decode(dst, src []byte) (n int, err error)
-	decodedLen(n int) int
+	// decodedLen(n int) int
 }
 
 type ID[UUID ~[uuidSize]byte, Enc encoding] struct {
diff --git a/id/uuid_test.go b/id/uuid_test.go
index ac5c8d5..fdbccfe 100644
--- a/id/uuid_test.go
+++ b/id/uuid_test.go
@@ -64,6 +64,20 @@ func TestJSONUnmarshal(t *testing.T) {
 			expected:      &FooPointer[Base64WithPadding]{ID: &ID[id, Base64WithPadding]{Value: uuid}},
 			errorAsserter: tst.NoError(),
 		},
+		{
+			name:          "Foo[Base62]",
+			input:         `{"id":"31reJxR0z0LERESS86rDe"}`,
+			destination:   &Foo[Base62]{ID: ID[id, Base62]{Value: zeroUUID}},
+			expected:      &Foo[Base62]{ID: ID[id, Base62]{Value: uuid}},
+			errorAsserter: tst.NoError(),
+		},
+		{
+			name:          "FooPointer[Base62]",
+			input:         `{"id":"31reJxR0z0LERESS86rDe"}`,
+			destination:   &FooPointer[Base62]{ID: nil},
+			expected:      &FooPointer[Base62]{ID: &ID[id, Base62]{Value: uuid}},
+			errorAsserter: tst.NoError(),
+		},
 	}
 
 	for _, tc := range unmarshalTests {
@@ -147,6 +161,12 @@ func TestJSONMarshal(t *testing.T) {
 			expectedJSON:  jsBase64,
 			errorAsserter: tst.NoError(),
 		},
+		{
+			name:          "Foo[Base62] uuid",
+			input:         Foo[Base62]{ID: ID[id, Base62]{Value: uuid}},
+			expectedJSON:  `{"id":"31reJxR0z0LERESS86rDe"}`,
+			errorAsserter: tst.NoError(),
+		},
 		{
 			name:          "*Foo[Base64] uuid",
 			input:         &Foo[Base64]{ID: ID[id, Base64]{Value: uuid}},

From 630e8a9088950bc5e72ca63d609f8c2bcb9f3bcc Mon Sep 17 00:00:00 2001
From: Kostas Stamatakis <moukoublen@gmail.com>
Date: Sun, 23 Nov 2025 12:10:15 +0200
Subject: [PATCH 15/15] fmt and gen

---
 id/go.mod        |   1 +
 id/mocks_test.go | 212 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 213 insertions(+)
 create mode 100644 id/mocks_test.go

diff --git a/id/go.mod b/id/go.mod
index 590029b..24b7595 100644
--- a/id/go.mod
+++ b/id/go.mod
@@ -10,5 +10,6 @@ require (
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/objx v0.5.2 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
diff --git a/id/mocks_test.go b/id/mocks_test.go
new file mode 100644
index 0000000..8fb0a3e
--- /dev/null
+++ b/id/mocks_test.go
@@ -0,0 +1,212 @@
+// Code generated by mockery; DO NOT EDIT.
+// github.com/vektra/mockery
+// template: testify
+
+package id
+
+import (
+	mock "github.com/stretchr/testify/mock"
+)
+
+// newMockencoding creates a new instance of mockencoding. It also registers a testing interface on the mock and a cleanup function to assert the mocks expectations.
+// The first argument is typically a *testing.T value.
+func newMockencoding(t interface {
+	mock.TestingT
+	Cleanup(func())
+}) *mockencoding {
+	mock := &mockencoding{}
+	mock.Mock.Test(t)
+
+	t.Cleanup(func() { mock.AssertExpectations(t) })
+
+	return mock
+}
+
+// mockencoding is an autogenerated mock type for the encoding type
+type mockencoding struct {
+	mock.Mock
+}
+
+type mockencoding_Expecter struct {
+	mock *mock.Mock
+}
+
+func (_m *mockencoding) EXPECT() *mockencoding_Expecter {
+	return &mockencoding_Expecter{mock: &_m.Mock}
+}
+
+// appendEncode provides a mock function for the type mockencoding
+func (_mock *mockencoding) appendEncode(dst []byte, src []byte) []byte {
+	ret := _mock.Called(dst, src)
+
+	if len(ret) == 0 {
+		panic("no return value specified for appendEncode")
+	}
+
+	var r0 []byte
+	if returnFunc, ok := ret.Get(0).(func([]byte, []byte) []byte); ok {
+		r0 = returnFunc(dst, src)
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).([]byte)
+		}
+	}
+	return r0
+}
+
+// mockencoding_appendEncode_Call is a *mock.Call that shadows Run/Return methods with type explicit version for method 'appendEncode'
+type mockencoding_appendEncode_Call struct {
+	*mock.Call
+}
+
+// appendEncode is a helper method to define mock.On call
+//   - dst []byte
+//   - src []byte
+func (_e *mockencoding_Expecter) appendEncode(dst interface{}, src interface{}) *mockencoding_appendEncode_Call {
+	return &mockencoding_appendEncode_Call{Call: _e.mock.On("appendEncode", dst, src)}
+}
+
+func (_c *mockencoding_appendEncode_Call) Run(run func(dst []byte, src []byte)) *mockencoding_appendEncode_Call {
+	_c.Call.Run(func(args mock.Arguments) {
+		var arg0 []byte
+		if args[0] != nil {
+			arg0 = args[0].([]byte)
+		}
+		var arg1 []byte
+		if args[1] != nil {
+			arg1 = args[1].([]byte)
+		}
+		run(
+			arg0,
+			arg1,
+		)
+	})
+	return _c
+}
+
+func (_c *mockencoding_appendEncode_Call) Return(bytes []byte) *mockencoding_appendEncode_Call {
+	_c.Call.Return(bytes)
+	return _c
+}
+
+func (_c *mockencoding_appendEncode_Call) RunAndReturn(run func(dst []byte, src []byte) []byte) *mockencoding_appendEncode_Call {
+	_c.Call.Return(run)
+	return _c
+}
+
+// decode provides a mock function for the type mockencoding
+func (_mock *mockencoding) decode(dst []byte, src []byte) (int, error) {
+	ret := _mock.Called(dst, src)
+
+	if len(ret) == 0 {
+		panic("no return value specified for decode")
+	}
+
+	var r0 int
+	var r1 error
+	if returnFunc, ok := ret.Get(0).(func([]byte, []byte) (int, error)); ok {
+		return returnFunc(dst, src)
+	}
+	if returnFunc, ok := ret.Get(0).(func([]byte, []byte) int); ok {
+		r0 = returnFunc(dst, src)
+	} else {
+		r0 = ret.Get(0).(int)
+	}
+	if returnFunc, ok := ret.Get(1).(func([]byte, []byte) error); ok {
+		r1 = returnFunc(dst, src)
+	} else {
+		r1 = ret.Error(1)
+	}
+	return r0, r1
+}
+
+// mockencoding_decode_Call is a *mock.Call that shadows Run/Return methods with type explicit version for method 'decode'
+type mockencoding_decode_Call struct {
+	*mock.Call
+}
+
+// decode is a helper method to define mock.On call
+//   - dst []byte
+//   - src []byte
+func (_e *mockencoding_Expecter) decode(dst interface{}, src interface{}) *mockencoding_decode_Call {
+	return &mockencoding_decode_Call{Call: _e.mock.On("decode", dst, src)}
+}
+
+func (_c *mockencoding_decode_Call) Run(run func(dst []byte, src []byte)) *mockencoding_decode_Call {
+	_c.Call.Run(func(args mock.Arguments) {
+		var arg0 []byte
+		if args[0] != nil {
+			arg0 = args[0].([]byte)
+		}
+		var arg1 []byte
+		if args[1] != nil {
+			arg1 = args[1].([]byte)
+		}
+		run(
+			arg0,
+			arg1,
+		)
+	})
+	return _c
+}
+
+func (_c *mockencoding_decode_Call) Return(n int, err error) *mockencoding_decode_Call {
+	_c.Call.Return(n, err)
+	return _c
+}
+
+func (_c *mockencoding_decode_Call) RunAndReturn(run func(dst []byte, src []byte) (int, error)) *mockencoding_decode_Call {
+	_c.Call.Return(run)
+	return _c
+}
+
+// encodedLen provides a mock function for the type mockencoding
+func (_mock *mockencoding) encodedLen(n int) int {
+	ret := _mock.Called(n)
+
+	if len(ret) == 0 {
+		panic("no return value specified for encodedLen")
+	}
+
+	var r0 int
+	if returnFunc, ok := ret.Get(0).(func(int) int); ok {
+		r0 = returnFunc(n)
+	} else {
+		r0 = ret.Get(0).(int)
+	}
+	return r0
+}
+
+// mockencoding_encodedLen_Call is a *mock.Call that shadows Run/Return methods with type explicit version for method 'encodedLen'
+type mockencoding_encodedLen_Call struct {
+	*mock.Call
+}
+
+// encodedLen is a helper method to define mock.On call
+//   - n int
+func (_e *mockencoding_Expecter) encodedLen(n interface{}) *mockencoding_encodedLen_Call {
+	return &mockencoding_encodedLen_Call{Call: _e.mock.On("encodedLen", n)}
+}
+
+func (_c *mockencoding_encodedLen_Call) Run(run func(n int)) *mockencoding_encodedLen_Call {
+	_c.Call.Run(func(args mock.Arguments) {
+		var arg0 int
+		if args[0] != nil {
+			arg0 = args[0].(int)
+		}
+		run(
+			arg0,
+		)
+	})
+	return _c
+}
+
+func (_c *mockencoding_encodedLen_Call) Return(n1 int) *mockencoding_encodedLen_Call {
+	_c.Call.Return(n1)
+	return _c
+}
+
+func (_c *mockencoding_encodedLen_Call) RunAndReturn(run func(n int) int) *mockencoding_encodedLen_Call {
+	_c.Call.Return(run)
+	return _c
+}