[自動コミット] esa.io API を操作する Go 製 CLI ツールを新規作成

- esa.io API クライアントの実装と単体テストを追加
- 記事の取得・検索・作成・更新を行うサブコマンドを実装
- GitHub Actions による CI ワークフローを設定
- プロジェクトの基本ファイル（README、.gitignore、LICENSE、go.mod）を作成

.github/workflows/ci.yml

@@ -0,0 +1,36 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: Build & Test
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+
+      - name: Set up Go
+        uses: actions/setup-go@v6
+        with:
+          go-version: 'stable'
+          check-latest: true
+          cache: true
+
+      - name: Verify dependencies
+        run: go mod verify
+
+      - name: Vet
+        run: go vet ./...
+
+      - name: Build
+        run: go build -v ./...
+
+      - name: Test
+        run: go test -race -v ./...

.gitignore

@@ -0,0 +1,4 @@
+/esacli
+/dist/
+*.test
+*.out

LICENSE

@@ -0,0 +1,13 @@
+        DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+                    Version 2, December 2004
+
+ Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
+
+ Everyone is permitted to copy and distribute verbatim or modified
+ copies of this license document, and changing it is allowed as long
+ as the name is changed.
+
+            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. You just DO WHAT THE FUCK YOU WANT TO.

README.md

@@ -0,0 +1,89 @@
+# esacli
+
+esa.io API v1 を叩く Go 製の CLI。記事の取得・検索・作成・更新ができる。
+
+## インストール
+
+```
+go install gitea.ssig33.com/ssig33/esacli@latest
+```
+
+もしくはソースからビルド。
+
+```
+git clone https://gitea.ssig33.com/ssig33/esacli
+cd esacli
+go build -o esacli .
+```
+
+## 設定
+
+以下の環境変数を読む。
+
+| 変数名 | 内容 |
+| --- | --- |
+| `ESA_TOKEN` | esa.io のアクセストークン (必須) |
+| `ESA_TEAM` | esa.io のチーム名 (必須) |
+| `ESA_BASE_URL` | API のベース URL を上書きする (省略可、デバッグ用) |
+
+トークンは `https://[team].esa.io/user/applications` から発行する。
+
+## 使い方
+
+```
+esacli <command> [options]
+```
+
+### get — 記事を 1 件取得
+
+```
+esacli get -number 102
+esacli get -number 102 -body   # body_md だけを出力
+```
+
+### search — 記事を検索
+
+```
+esacli search -q "esa API"
+esacli search -q "tag:dev" -per-page 50 -sort updated -order desc
+```
+
+検索クエリの書式は [esa の検索方法ドキュメント](https://docs.esa.io/posts/104) を参照。
+
+### create — 記事を作成
+
+```
+esacli create -name "新しい記事" -body "# 本文" -tags "go,cli" -category "dev/2026/05"
+esacli create -name "長文記事" -body-file ./article.md -wip=false -message "first commit"
+echo "# stdin から本文" | esacli create -name "stdin 経由" -body-file -
+```
+
+`-wip` のデフォルトは `true`。
+
+### update — 記事を更新
+
+```
+esacli update -number 5 -name "タイトル更新"
+esacli update -number 5 -body-file ./article.md -message "本文更新"
+esacli update -number 5 -wip false
+```
+
+`-wip` は `true` / `false` を文字列で渡す。指定しなければ変更しない。
+
+## 出力
+
+成功時は JSON を整形して標準出力に書く。失敗時は標準エラーにメッセージを出し、終了コード `1` で終わる。
+
+## 開発
+
+```
+go test ./...
+go vet ./...
+go build ./...
+```
+
+`main` ブランチへの push と PR で GitHub Actions が `go vet`・`go build`・`go test -race` を実行する。
+
+## ライセンス
+
+WTFPL。詳しくは [LICENSE](./LICENSE)。

esa/client.go

@@ -0,0 +1,224 @@
+package esa
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+	"time"
+)
+
+const defaultBaseURL = "https://api.esa.io"
+
+type Client struct {
+	BaseURL    string
+	Team       string
+	Token      string
+	HTTPClient *http.Client
+}
+
+func NewClient(team, token string) *Client {
+	return &Client{
+		BaseURL:    defaultBaseURL,
+		Team:       team,
+		Token:      token,
+		HTTPClient: &http.Client{Timeout: 30 * time.Second},
+	}
+}
+
+type User struct {
+	Myself     bool   `json:"myself"`
+	Name       string `json:"name"`
+	ScreenName string `json:"screen_name"`
+	Icon       string `json:"icon"`
+}
+
+type Post struct {
+	Number          int      `json:"number"`
+	Name            string   `json:"name"`
+	FullName        string   `json:"full_name"`
+	WIP             bool     `json:"wip"`
+	BodyMD          string   `json:"body_md"`
+	BodyHTML        string   `json:"body_html"`
+	CreatedAt       string   `json:"created_at"`
+	UpdatedAt       string   `json:"updated_at"`
+	Message         string   `json:"message"`
+	URL             string   `json:"url"`
+	Tags            []string `json:"tags"`
+	Category        string   `json:"category"`
+	RevisionNumber  int      `json:"revision_number"`
+	CreatedBy       User     `json:"created_by"`
+	UpdatedBy       User     `json:"updated_by"`
+	Kind            string   `json:"kind"`
+	CommentsCount   int      `json:"comments_count"`
+	TasksCount      int      `json:"tasks_count"`
+	DoneTasksCount  int      `json:"done_tasks_count"`
+	StargazersCount int      `json:"stargazers_count"`
+	WatchersCount   int      `json:"watchers_count"`
+	Star            bool     `json:"star"`
+	Watch           bool     `json:"watch"`
+}
+
+type PostsResponse struct {
+	Posts      []Post `json:"posts"`
+	PrevPage   *int   `json:"prev_page"`
+	NextPage   *int   `json:"next_page"`
+	TotalCount int    `json:"total_count"`
+	Page       int    `json:"page"`
+	PerPage    int    `json:"per_page"`
+	MaxPerPage int    `json:"max_per_page"`
+}
+
+type PostInput struct {
+	Name     string   `json:"name,omitempty"`
+	BodyMD   string   `json:"body_md,omitempty"`
+	Tags     []string `json:"tags,omitempty"`
+	Category string   `json:"category,omitempty"`
+	WIP      *bool    `json:"wip,omitempty"`
+	Message  string   `json:"message,omitempty"`
+}
+
+type postCreateRequest struct {
+	Post PostInput `json:"post"`
+}
+
+type APIError struct {
+	StatusCode int
+	ErrorCode  string `json:"error"`
+	Message    string `json:"message"`
+}
+
+func (e *APIError) Error() string {
+	if e.ErrorCode == "" {
+		return fmt.Sprintf("esa API error: status=%d", e.StatusCode)
+	}
+	return fmt.Sprintf("esa API error: status=%d error=%s message=%s", e.StatusCode, e.ErrorCode, e.Message)
+}
+
+func (c *Client) do(ctx context.Context, method, path string, query url.Values, body any) ([]byte, error) {
+	u, err := url.Parse(c.BaseURL + path)
+	if err != nil {
+		return nil, fmt.Errorf("parse url: %w", err)
+	}
+	if len(query) > 0 {
+		u.RawQuery = query.Encode()
+	}
+
+	var reqBody io.Reader
+	if body != nil {
+		b, err := json.Marshal(body)
+		if err != nil {
+			return nil, fmt.Errorf("marshal body: %w", err)
+		}
+		reqBody = bytes.NewReader(b)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, method, u.String(), reqBody)
+	if err != nil {
+		return nil, fmt.Errorf("new request: %w", err)
+	}
+	req.Header.Set("Authorization", "Bearer "+c.Token)
+	req.Header.Set("Accept", "application/json")
+	if body != nil {
+		req.Header.Set("Content-Type", "application/json")
+	}
+
+	resp, err := c.HTTPClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("http: %w", err)
+	}
+	defer resp.Body.Close()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("read body: %w", err)
+	}
+
+	if resp.StatusCode >= 400 {
+		apiErr := &APIError{StatusCode: resp.StatusCode}
+		_ = json.Unmarshal(respBody, apiErr)
+		return nil, apiErr
+	}
+
+	return respBody, nil
+}
+
+func (c *Client) GetPost(ctx context.Context, number int) (*Post, error) {
+	path := fmt.Sprintf("/v1/teams/%s/posts/%d", url.PathEscape(c.Team), number)
+	body, err := c.do(ctx, http.MethodGet, path, nil, nil)
+	if err != nil {
+		return nil, err
+	}
+	var p Post
+	if err := json.Unmarshal(body, &p); err != nil {
+		return nil, fmt.Errorf("unmarshal post: %w", err)
+	}
+	return &p, nil
+}
+
+type SearchOptions struct {
+	Query   string
+	Page    int
+	PerPage int
+	Sort    string
+	Order   string
+}
+
+func (c *Client) SearchPosts(ctx context.Context, opts SearchOptions) (*PostsResponse, error) {
+	path := fmt.Sprintf("/v1/teams/%s/posts", url.PathEscape(c.Team))
+	q := url.Values{}
+	if opts.Query != "" {
+		q.Set("q", opts.Query)
+	}
+	if opts.Page > 0 {
+		q.Set("page", strconv.Itoa(opts.Page))
+	}
+	if opts.PerPage > 0 {
+		q.Set("per_page", strconv.Itoa(opts.PerPage))
+	}
+	if opts.Sort != "" {
+		q.Set("sort", opts.Sort)
+	}
+	if opts.Order != "" {
+		q.Set("order", opts.Order)
+	}
+	body, err := c.do(ctx, http.MethodGet, path, q, nil)
+	if err != nil {
+		return nil, err
+	}
+	var r PostsResponse
+	if err := json.Unmarshal(body, &r); err != nil {
+		return nil, fmt.Errorf("unmarshal posts: %w", err)
+	}
+	return &r, nil
+}
+
+func (c *Client) CreatePost(ctx context.Context, input PostInput) (*Post, error) {
+	path := fmt.Sprintf("/v1/teams/%s/posts", url.PathEscape(c.Team))
+	body, err := c.do(ctx, http.MethodPost, path, nil, postCreateRequest{Post: input})
+	if err != nil {
+		return nil, err
+	}
+	var p Post
+	if err := json.Unmarshal(body, &p); err != nil {
+		return nil, fmt.Errorf("unmarshal post: %w", err)
+	}
+	return &p, nil
+}
+
+func (c *Client) UpdatePost(ctx context.Context, number int, input PostInput) (*Post, error) {
+	path := fmt.Sprintf("/v1/teams/%s/posts/%d", url.PathEscape(c.Team), number)
+	body, err := c.do(ctx, http.MethodPatch, path, nil, postCreateRequest{Post: input})
+	if err != nil {
+		return nil, err
+	}
+	var p Post
+	if err := json.Unmarshal(body, &p); err != nil {
+		return nil, fmt.Errorf("unmarshal post: %w", err)
+	}
+	return &p, nil
+}

esa/client_test.go

@@ -0,0 +1,223 @@
+package esa
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func newTestClient(t *testing.T, handler http.Handler) (*Client, func()) {
+	t.Helper()
+	srv := httptest.NewServer(handler)
+	c := NewClient("docs", "test-token")
+	c.BaseURL = srv.URL
+	return c, srv.Close
+}
+
+func TestGetPost(t *testing.T) {
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got, want := r.Method, http.MethodGet; got != want {
+			t.Errorf("method = %q, want %q", got, want)
+		}
+		if got, want := r.URL.Path, "/v1/teams/docs/posts/5"; got != want {
+			t.Errorf("path = %q, want %q", got, want)
+		}
+		if got, want := r.Header.Get("Authorization"), "Bearer test-token"; got != want {
+			t.Errorf("auth header = %q, want %q", got, want)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{
+			"number": 5,
+			"name": "hi!",
+			"full_name": "dev/2015/05/10/hi! #api #dev",
+			"wip": false,
+			"body_md": "# Getting Started\n",
+			"tags": ["api", "dev"],
+			"category": "dev/2015/05/10",
+			"revision_number": 1
+		}`))
+	})
+	c, cleanup := newTestClient(t, handler)
+	defer cleanup()
+
+	post, err := c.GetPost(context.Background(), 5)
+	if err != nil {
+		t.Fatalf("GetPost: %v", err)
+	}
+	if post.Number != 5 {
+		t.Errorf("Number = %d, want 5", post.Number)
+	}
+	if post.Name != "hi!" {
+		t.Errorf("Name = %q, want %q", post.Name, "hi!")
+	}
+	if got, want := post.BodyMD, "# Getting Started\n"; got != want {
+		t.Errorf("BodyMD = %q, want %q", got, want)
+	}
+	if got, want := post.Tags, []string{"api", "dev"}; !equalStrings(got, want) {
+		t.Errorf("Tags = %v, want %v", got, want)
+	}
+}
+
+func TestSearchPosts(t *testing.T) {
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got, want := r.Method, http.MethodGet; got != want {
+			t.Errorf("method = %q, want %q", got, want)
+		}
+		if got, want := r.URL.Path, "/v1/teams/docs/posts"; got != want {
+			t.Errorf("path = %q, want %q", got, want)
+		}
+		q := r.URL.Query()
+		if got, want := q.Get("q"), "hello"; got != want {
+			t.Errorf("q param = %q, want %q", got, want)
+		}
+		if got, want := q.Get("per_page"), "10"; got != want {
+			t.Errorf("per_page = %q, want %q", got, want)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{
+			"posts": [
+				{"number": 1, "name": "hi!", "body_md": "# Getting Started"},
+				{"number": 2, "name": "bye!", "body_md": "# Bye"}
+			],
+			"prev_page": null,
+			"next_page": null,
+			"total_count": 2,
+			"page": 1,
+			"per_page": 10,
+			"max_per_page": 100
+		}`))
+	})
+	c, cleanup := newTestClient(t, handler)
+	defer cleanup()
+
+	resp, err := c.SearchPosts(context.Background(), SearchOptions{Query: "hello", PerPage: 10})
+	if err != nil {
+		t.Fatalf("SearchPosts: %v", err)
+	}
+	if resp.TotalCount != 2 {
+		t.Errorf("TotalCount = %d, want 2", resp.TotalCount)
+	}
+	if len(resp.Posts) != 2 {
+		t.Fatalf("len(Posts) = %d, want 2", len(resp.Posts))
+	}
+	if resp.Posts[0].Number != 1 {
+		t.Errorf("Posts[0].Number = %d, want 1", resp.Posts[0].Number)
+	}
+}
+
+func TestCreatePost(t *testing.T) {
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got, want := r.Method, http.MethodPost; got != want {
+			t.Errorf("method = %q, want %q", got, want)
+		}
+		if got, want := r.URL.Path, "/v1/teams/docs/posts"; got != want {
+			t.Errorf("path = %q, want %q", got, want)
+		}
+		if got, want := r.Header.Get("Content-Type"), "application/json"; got != want {
+			t.Errorf("content-type = %q, want %q", got, want)
+		}
+		var body struct {
+			Post PostInput `json:"post"`
+		}
+		raw, _ := io.ReadAll(r.Body)
+		if err := json.Unmarshal(raw, &body); err != nil {
+			t.Fatalf("decode body: %v (raw=%s)", err, raw)
+		}
+		if body.Post.Name != "hi!" {
+			t.Errorf("post.name = %q, want %q", body.Post.Name, "hi!")
+		}
+		if body.Post.WIP == nil || *body.Post.WIP {
+			t.Errorf("post.wip should be false (got %v)", body.Post.WIP)
+		}
+		w.WriteHeader(http.StatusCreated)
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{
+			"number": 5,
+			"name": "hi!",
+			"body_md": "# Getting Started\n",
+			"wip": false,
+			"category": "dev/2015/05/10",
+			"tags": ["api", "dev"]
+		}`))
+	})
+	c, cleanup := newTestClient(t, handler)
+	defer cleanup()
+
+	wip := false
+	post, err := c.CreatePost(context.Background(), PostInput{
+		Name:     "hi!",
+		BodyMD:   "# Getting Started\n",
+		Tags:     []string{"api", "dev"},
+		Category: "dev/2015/05/10",
+		WIP:      &wip,
+		Message:  "first commit",
+	})
+	if err != nil {
+		t.Fatalf("CreatePost: %v", err)
+	}
+	if post.Number != 5 {
+		t.Errorf("Number = %d, want 5", post.Number)
+	}
+	if post.WIP {
+		t.Errorf("WIP = true, want false")
+	}
+}
+
+func TestUpdatePost(t *testing.T) {
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got, want := r.Method, http.MethodPatch; got != want {
+			t.Errorf("method = %q, want %q", got, want)
+		}
+		if got, want := r.URL.Path, "/v1/teams/docs/posts/5"; got != want {
+			t.Errorf("path = %q, want %q", got, want)
+		}
+		var body struct {
+			Post PostInput `json:"post"`
+		}
+		raw, _ := io.ReadAll(r.Body)
+		if err := json.Unmarshal(raw, &body); err != nil {
+			t.Fatalf("decode body: %v", err)
+		}
+		if body.Post.Name != "updated" {
+			t.Errorf("post.name = %q, want %q", body.Post.Name, "updated")
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{
+			"number": 5,
+			"name": "updated",
+			"body_md": "new body",
+			"revision_number": 2
+		}`))
+	})
+	c, cleanup := newTestClient(t, handler)
+	defer cleanup()
+
+	post, err := c.UpdatePost(context.Background(), 5, PostInput{
+		Name:   "updated",
+		BodyMD: "new body",
+	})
+	if err != nil {
+		t.Fatalf("UpdatePost: %v", err)
+	}
+	if post.Name != "updated" {
+		t.Errorf("Name = %q, want %q", post.Name, "updated")
+	}
+	if post.RevisionNumber != 2 {
+		t.Errorf("RevisionNumber = %d, want 2", post.RevisionNumber)
+	}
+}
+
+func equalStrings(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}

go.mod

@@ -0,0 +1,3 @@
+module gitea.ssig33.com/ssig33/esacli
+
+go 1.25.4

main.go

@@ -0,0 +1,261 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+
+	"gitea.ssig33.com/ssig33/esacli/esa"
+)
+
+const usage = `esacli - esa.io API CLI
+
+Usage:
+  esacli <command> [options]
+
+Commands:
+  get      Fetch a single post
+  search   Search posts
+  create   Create a new post
+  update   Update an existing post
+  help     Show this help
+
+Environment variables:
+  ESA_TOKEN  esa.io API access token (required)
+  ESA_TEAM   esa.io team name (required)
+
+Run "esacli <command> -h" for command-specific options.
+`
+
+func main() {
+	if err := run(os.Args[1:], os.Stdout, os.Stderr); err != nil {
+		fmt.Fprintln(os.Stderr, "error:", err)
+		os.Exit(1)
+	}
+}
+
+func run(args []string, stdout, stderr io.Writer) error {
+	if len(args) == 0 {
+		fmt.Fprint(stderr, usage)
+		return errors.New("no command specified")
+	}
+
+	cmd := args[0]
+	rest := args[1:]
+
+	switch cmd {
+	case "help", "-h", "--help":
+		fmt.Fprint(stdout, usage)
+		return nil
+	case "get":
+		return runGet(rest, stdout)
+	case "search":
+		return runSearch(rest, stdout)
+	case "create":
+		return runCreate(rest, stdout)
+	case "update":
+		return runUpdate(rest, stdout)
+	default:
+		fmt.Fprint(stderr, usage)
+		return fmt.Errorf("unknown command: %s", cmd)
+	}
+}
+
+func newClient() (*esa.Client, error) {
+	token := os.Getenv("ESA_TOKEN")
+	if token == "" {
+		return nil, errors.New("ESA_TOKEN is not set")
+	}
+	team := os.Getenv("ESA_TEAM")
+	if team == "" {
+		return nil, errors.New("ESA_TEAM is not set")
+	}
+	c := esa.NewClient(team, token)
+	if base := os.Getenv("ESA_BASE_URL"); base != "" {
+		c.BaseURL = base
+	}
+	return c, nil
+}
+
+func runGet(args []string, stdout io.Writer) error {
+	fs := flag.NewFlagSet("get", flag.ContinueOnError)
+	number := fs.Int("number", 0, "post number (required)")
+	bodyOnly := fs.Bool("body", false, "print only body_md instead of JSON")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+	if *number <= 0 {
+		return errors.New("get: -number is required")
+	}
+	c, err := newClient()
+	if err != nil {
+		return err
+	}
+	post, err := c.GetPost(context.Background(), *number)
+	if err != nil {
+		return err
+	}
+	if *bodyOnly {
+		fmt.Fprint(stdout, post.BodyMD)
+		return nil
+	}
+	return printJSON(stdout, post)
+}
+
+func runSearch(args []string, stdout io.Writer) error {
+	fs := flag.NewFlagSet("search", flag.ContinueOnError)
+	query := fs.String("q", "", "search query")
+	page := fs.Int("page", 0, "page number")
+	perPage := fs.Int("per-page", 0, "results per page (max 100)")
+	sort := fs.String("sort", "", "sort field (updated, created, number, stars, watches, comments, best_match)")
+	order := fs.String("order", "", "order (desc, asc)")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+	c, err := newClient()
+	if err != nil {
+		return err
+	}
+	resp, err := c.SearchPosts(context.Background(), esa.SearchOptions{
+		Query:   *query,
+		Page:    *page,
+		PerPage: *perPage,
+		Sort:    *sort,
+		Order:   *order,
+	})
+	if err != nil {
+		return err
+	}
+	return printJSON(stdout, resp)
+}
+
+func runCreate(args []string, stdout io.Writer) error {
+	fs := flag.NewFlagSet("create", flag.ContinueOnError)
+	name := fs.String("name", "", "post title (required)")
+	bodyFile := fs.String("body-file", "", "path to file containing body_md ('-' for stdin)")
+	body := fs.String("body", "", "body_md (use -body-file for longer content)")
+	tagsCSV := fs.String("tags", "", "comma-separated tags")
+	category := fs.String("category", "", "category")
+	wip := fs.Bool("wip", true, "WIP flag")
+	message := fs.String("message", "", "commit-like message")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+	if *name == "" {
+		return errors.New("create: -name is required")
+	}
+	bodyMD, err := resolveBody(*body, *bodyFile)
+	if err != nil {
+		return err
+	}
+	c, err := newClient()
+	if err != nil {
+		return err
+	}
+	wipVal := *wip
+	post, err := c.CreatePost(context.Background(), esa.PostInput{
+		Name:     *name,
+		BodyMD:   bodyMD,
+		Tags:     splitCSV(*tagsCSV),
+		Category: *category,
+		WIP:      &wipVal,
+		Message:  *message,
+	})
+	if err != nil {
+		return err
+	}
+	return printJSON(stdout, post)
+}
+
+func runUpdate(args []string, stdout io.Writer) error {
+	fs := flag.NewFlagSet("update", flag.ContinueOnError)
+	number := fs.Int("number", 0, "post number (required)")
+	name := fs.String("name", "", "new title")
+	bodyFile := fs.String("body-file", "", "path to file containing body_md ('-' for stdin)")
+	body := fs.String("body", "", "body_md (use -body-file for longer content)")
+	tagsCSV := fs.String("tags", "", "comma-separated tags")
+	category := fs.String("category", "", "category")
+	wipFlag := fs.String("wip", "", "WIP flag (true/false); empty leaves unchanged")
+	message := fs.String("message", "", "commit-like message")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+	if *number <= 0 {
+		return errors.New("update: -number is required")
+	}
+	bodyMD, err := resolveBody(*body, *bodyFile)
+	if err != nil {
+		return err
+	}
+	input := esa.PostInput{
+		Name:     *name,
+		BodyMD:   bodyMD,
+		Tags:     splitCSV(*tagsCSV),
+		Category: *category,
+		Message:  *message,
+	}
+	if *wipFlag != "" {
+		v, err := strconv.ParseBool(*wipFlag)
+		if err != nil {
+			return fmt.Errorf("update: -wip: %w", err)
+		}
+		input.WIP = &v
+	}
+	c, err := newClient()
+	if err != nil {
+		return err
+	}
+	post, err := c.UpdatePost(context.Background(), *number, input)
+	if err != nil {
+		return err
+	}
+	return printJSON(stdout, post)
+}
+
+func resolveBody(inline, file string) (string, error) {
+	if inline != "" && file != "" {
+		return "", errors.New("specify only one of -body or -body-file")
+	}
+	if file == "" {
+		return inline, nil
+	}
+	if file == "-" {
+		b, err := io.ReadAll(os.Stdin)
+		if err != nil {
+			return "", fmt.Errorf("read stdin: %w", err)
+		}
+		return string(b), nil
+	}
+	b, err := os.ReadFile(file)
+	if err != nil {
+		return "", fmt.Errorf("read body file: %w", err)
+	}
+	return string(b), nil
+}
+
+func splitCSV(s string) []string {
+	if s == "" {
+		return nil
+	}
+	parts := strings.Split(s, ",")
+	out := make([]string, 0, len(parts))
+	for _, p := range parts {
+		p = strings.TrimSpace(p)
+		if p != "" {
+			out = append(out, p)
+		}
+	}
+	return out
+}
+
+func printJSON(w io.Writer, v any) error {
+	enc := json.NewEncoder(w)
+	enc.SetIndent("", "  ")
+	return enc.Encode(v)
+}