diff --git a/go.mod b/go.mod
index 2233d108..013fe1f4 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/ufukty/kask
 
-go 1.24.2
+go 1.24.4
 
 require (
 	github.com/alecthomas/chroma v0.10.0
@@ -11,4 +11,5 @@ require (
 require (
 	github.com/dlclark/regexp2 v1.11.5 // indirect
 	github.com/stretchr/testify v1.8.1 // indirect
+	github.com/ufukty/diagramer v0.1.0 // indirect
 )
diff --git a/go.sum b/go.sum
index 8363808d..9df718e9 100644
--- a/go.sum
+++ b/go.sum
@@ -18,6 +18,10 @@ github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/ufukty/diagramer v0.0.1 h1:ZUrW+zWZBMOVp4HWoRkN3/klZD5WFFojUOubN50e7NA=
+github.com/ufukty/diagramer v0.0.1/go.mod h1:fLoTnqzvqEqIifDyXANoPbM8g87a+x2CpsIRBDo9VaQ=
+github.com/ufukty/diagramer v0.1.0 h1:9VXJoj7B0Hd70zjb5oV0yxqlRYdZ2L/VgqsA2UD63ew=
+github.com/ufukty/diagramer v0.1.0/go.mod h1:fLoTnqzvqEqIifDyXANoPbM8g87a+x2CpsIRBDo9VaQ=
 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 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/internal/builder/markdown/hook/diagramer/render.go b/internal/builder/markdown/hook/diagramer/render.go
new file mode 100644
index 00000000..d98b922a
--- /dev/null
+++ b/internal/builder/markdown/hook/diagramer/render.go
@@ -0,0 +1,12 @@
+package diagramer
+
+import (
+	"io"
+
+	"github.com/gomarkdown/markdown/ast"
+	"github.com/ufukty/diagramer/pkg/sequence/parser"
+)
+
+func Render(w io.Writer, node *ast.CodeBlock, entering bool) (ast.WalkStatus, bool) {
+	parser.Reader(node.Literal)
+}
diff --git a/vendor/github.com/ufukty/diagramer/LICENSE b/vendor/github.com/ufukty/diagramer/LICENSE
new file mode 100644
index 00000000..f264da86
--- /dev/null
+++ b/vendor/github.com/ufukty/diagramer/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2025 Ufuktan Yıldırım
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/vendor/github.com/ufukty/diagramer/pkg/sequence/parser/file.go b/vendor/github.com/ufukty/diagramer/pkg/sequence/parser/file.go
new file mode 100644
index 00000000..e0db6987
--- /dev/null
+++ b/vendor/github.com/ufukty/diagramer/pkg/sequence/parser/file.go
@@ -0,0 +1,60 @@
+package parser
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/ufukty/diagramer/pkg/sequence/parser/parse"
+	"github.com/ufukty/diagramer/pkg/sequence/parser/parse/ast"
+)
+
+func Reader(src io.Reader) (*ast.Diagram, error) {
+	diagram := &ast.Diagram{
+		Lifelines:  make(map[string]*ast.Lifeline),
+		Messages:   []*ast.Message{},
+		AutoNumber: false,
+	}
+
+	scanner := bufio.NewScanner(src)
+	for i := 0; scanner.Scan(); i++ {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || strings.HasPrefix(line, "%%") {
+			continue
+		}
+
+		switch {
+		case line == "sequenceDiagram":
+			continue
+
+		case line == "autoNumber":
+			diagram.AutoNumber = true
+
+		case strings.HasPrefix(line, "participant") || strings.HasPrefix(line, "actor"):
+			if p := parse.Lifeline(line); p != nil {
+				diagram.Lifelines[p.Name] = p
+			}
+
+		case strings.Contains(line, "->>"):
+			if m := parse.Message(line); m != nil {
+				diagram.Messages = append(diagram.Messages, m)
+			}
+
+		default:
+			fmt.Printf("skipping line #%d: %s\n", i, line)
+		}
+	}
+
+	return diagram, nil
+}
+
+func File(path string) (*ast.Diagram, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, fmt.Errorf("opening: %w", err)
+	}
+	defer file.Close() //nolint:errcheck
+	return Reader(file)
+}
diff --git a/vendor/github.com/ufukty/diagramer/pkg/sequence/parser/parse/ast/ast.go b/vendor/github.com/ufukty/diagramer/pkg/sequence/parser/parse/ast/ast.go
new file mode 100644
index 00000000..45c5411b
--- /dev/null
+++ b/vendor/github.com/ufukty/diagramer/pkg/sequence/parser/parse/ast/ast.go
@@ -0,0 +1,21 @@
+package ast
+
+// Lifeline represents a diagram participant or actor
+type Lifeline struct {
+	Type  string
+	Alias string
+	Name  string
+}
+
+// Message represents a message between lifelines
+type Message struct {
+	From    string
+	To      string
+	Content string
+}
+
+type Diagram struct {
+	Lifelines  map[string]*Lifeline
+	Messages   []*Message
+	AutoNumber bool
+}
diff --git a/vendor/github.com/ufukty/diagramer/pkg/sequence/parser/parse/parse.go b/vendor/github.com/ufukty/diagramer/pkg/sequence/parser/parse/parse.go
new file mode 100644
index 00000000..5d0a101a
--- /dev/null
+++ b/vendor/github.com/ufukty/diagramer/pkg/sequence/parser/parse/parse.go
@@ -0,0 +1,44 @@
+package parse
+
+import (
+	"regexp"
+
+	"github.com/ufukty/diagramer/pkg/sequence/parser/parse/ast"
+)
+
+var (
+	regexLifeline = regexp.MustCompile(`(participant|actor)\s+(\w+)(?:\s+as\s+(.+))?`)
+	regexMessage  = regexp.MustCompile(`([^\s-]+)\s*(?:->>[-+]?)\s*([^\s:]*)(?::\s*(.+))?`)
+)
+
+func Lifeline(line string) *ast.Lifeline {
+	match := regexLifeline.FindStringSubmatch(line)
+	if len(match) < 3 {
+		return nil
+	}
+	p := &ast.Lifeline{
+		Type:  match[1],
+		Alias: "",
+		Name:  match[2],
+	}
+	if len(match) > 3 {
+		p.Alias = match[3]
+	}
+	return p
+}
+
+func Message(line string) *ast.Message {
+	match := regexMessage.FindStringSubmatch(line)
+	if len(match) < 4 {
+		return nil
+	}
+	m := &ast.Message{
+		From:    match[1],
+		To:      match[2],
+		Content: "",
+	}
+	if len(match) > 3 {
+		m.Content = match[3]
+	}
+	return m
+}
diff --git a/vendor/modules.txt b/vendor/modules.txt
index 64b3a742..fdbbf286 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -43,6 +43,11 @@ github.com/gomarkdown/markdown/html
 github.com/gomarkdown/markdown/parser
 # github.com/stretchr/testify v1.8.1
 ## explicit; go 1.13
+# github.com/ufukty/diagramer v0.1.0
+## explicit; go 1.24.4
+github.com/ufukty/diagramer/pkg/sequence/parser
+github.com/ufukty/diagramer/pkg/sequence/parser/parse
+github.com/ufukty/diagramer/pkg/sequence/parser/parse/ast
 # gopkg.in/yaml.v3 v3.0.1
 ## explicit
 gopkg.in/yaml.v3