v0: stdlib-only Discourse client — categories/topics/posts + raw passthrough

Covers the MOPAC briefing/report surface (Redmine 495 Part A): category
list/create (create needs the admin-scoped key; current key 403s, typed
as ErrForbidden), topic create/list/latest/get, post create/update/get,
current-user identity probe, and a Do() JSON passthrough so unmodeled
endpoints need no client release. Key is env/constructor-only, never a
flag, never logged; errors classify via errors.Is. Fake-server unit
tests + containerized end-to-end smoke (redaction sweep included); live
reads verified against community.turnsys.com.

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

posts.go

@@ -0,0 +1,121 @@
+// Posts: create (POST /posts.json — replies or topic creation, the same
+// endpoint), update (PUT /posts/<id>.json), and the session identity
+// check (GET /session/current.json) used by smoke tests and health probes.
+package discourse
+
+import (
+	"context"
+	"fmt"
+	"strings"
+)
+
+// Post is the post payload subset callers use.
+type Post struct {
+	ID         int    `json:"id"`
+	TopicID    int    `json:"topic_id"`
+	PostNumber int    `json:"post_number"`
+	Raw        string `json:"raw"`
+	Cooked     string `json:"cooked"`
+	CreatedAt  string `json:"created_at"`
+	UpdatedAt  string `json:"updated_at"`
+}
+
+// CreatePostRequest posts into an existing topic (topic_id set) or
+// creates a topic (topic_id zero + title + category — prefer
+// CreateTopic for that path).
+type CreatePostRequest struct {
+	TopicID  int    `json:"topic_id"`
+	Raw      string `json:"raw"`
+	Title    string `json:"title,omitempty"`
+	Category int    `json:"category,omitempty"`
+}
+
+// CreatePostResult is the POST /posts.json response.
+type CreatePostResult struct {
+	PostID    int    `json:"id"`
+	TopicID   int    `json:"topic_id"`
+	TopicSlug string `json:"topic_slug"`
+}
+
+// CreatePost posts markdown into a topic and returns the ids.
+func (c *Client) CreatePost(ctx context.Context, req CreatePostRequest) (*CreatePostResult, error) {
+	if req.TopicID <= 0 {
+		return nil, fmt.Errorf("%w: topic_id is required (use CreateTopic for new topics)", ErrInvalidRequest)
+	}
+	if strings.TrimSpace(req.Raw) == "" {
+		return nil, fmt.Errorf("%w: post raw body is required", ErrInvalidRequest)
+	}
+	var out CreatePostResult
+	if err := c.Post(ctx, "/posts.json", req, &out); err != nil {
+		return nil, err
+	}
+	return &out, nil
+}
+
+// UpdatePost replaces a post's markdown body (PUT /posts/<id>.json) with
+// an optional edit reason.
+func (c *Client) UpdatePost(ctx context.Context, postID int, raw, editReason string) (*Post, error) {
+	if postID <= 0 {
+		return nil, fmt.Errorf("%w: post id must be > 0", ErrInvalidRequest)
+	}
+	if strings.TrimSpace(raw) == "" {
+		return nil, fmt.Errorf("%w: post raw body is required", ErrInvalidRequest)
+	}
+	body := map[string]any{
+		"post": map[string]any{
+			"raw": raw,
+		},
+	}
+	if editReason != "" {
+		body["post"].(map[string]any)["edit_reason"] = editReason
+	}
+	var post struct {
+		Post Post `json:"post"`
+	}
+	if err := c.Put(ctx, "/posts/"+fmt.Sprint(postID)+".json", body, &post); err != nil {
+		return nil, err
+	}
+	if post.Post.ID == 0 {
+		return nil, fmt.Errorf("%w: post updated but response carries no id", ErrMalformedResponse)
+	}
+	return &post.Post, nil
+}
+
+// GetPost fetches one post by id (GET /posts/<id>.json).
+func (c *Client) GetPost(ctx context.Context, postID int) (*Post, error) {
+	if postID <= 0 {
+		return nil, fmt.Errorf("%w: post id must be > 0", ErrInvalidRequest)
+	}
+	var payload struct {
+		Post Post `json:"post"`
+	}
+	if err := c.Get(ctx, "/posts/"+fmt.Sprint(postID)+".json", &payload); err != nil {
+		return nil, err
+	}
+	if payload.Post.ID == 0 {
+		return nil, fmt.Errorf("%w: post response carries no id", ErrMalformedResponse)
+	}
+	return &payload.Post, nil
+}
+
+// CurrentUser is the identity the key acts as — the cheapest live
+// verification of url + key + username (any 2xx means the trio works).
+type CurrentUser struct {
+	ID       int    `json:"id"`
+	Username string `json:"username"`
+	Admin    bool   `json:"admin"`
+}
+
+// CurrentUser runs GET /session/current.json.
+func (c *Client) CurrentUser(ctx context.Context) (*CurrentUser, error) {
+	var payload struct {
+		CurrentUser CurrentUser `json:"current_user"`
+	}
+	if err := c.Get(ctx, "/session/current.json", &payload); err != nil {
+		return nil, err
+	}
+	if payload.CurrentUser.Username == "" {
+		return nil, fmt.Errorf("%w: no current_user in response", ErrMalformedResponse)
+	}
+	return &payload.CurrentUser, nil
+}