Initial release of go-telegram

A fully-generated, strongly-typed Go client for the Telegram Bot API.

* 176 methods + 301 types generated from Bot API v10.0
* 1408 auto-generated tests (8 scenarios per method)
* Typed unions throughout — no 'any' in the public surface
* Pluggable HTTP transport and JSON codec (default goccy/go-json)
* Built-in retry middleware honouring Telegram's retry_after
* Generic dispatcher with filters and conversation handlers
* Self-verifying codegen pipeline (regen → audit → emit → run tests)
* 14 example bots covering common patterns

client/multipart.go

@@ -0,0 +1,146 @@
+package client
+
+import (
+	"context"
+	"github.com/goccy/go-json"
+	"io"
+	"mime/multipart"
+	"net/http"
+)
+
+// multipartRequest is implemented by request structs that may carry an
+// InputFile. The codegen emits this interface for any method whose IR
+// MethodDecl.HasFiles is true.
+//
+// HasFile returns true if at least one file field is set; if false, the
+// request is sent as plain JSON via the regular Call path.
+//
+// MultipartFiles returns one entry per file field that should be uploaded.
+// The accompanying scalar/object fields are returned by MultipartFields.
+type multipartRequest interface {
+	HasFile() bool
+	MultipartFiles() []MultipartFile
+	MultipartFields() map[string]string
+}
+
+// MultipartFile describes a single file part in a multipart upload.
+type MultipartFile struct {
+	FieldName string
+	Filename  string
+	Reader    io.Reader
+}
+
+// callMultipart performs a multipart/form-data POST. It is invoked by Call
+// when the request implements multipartRequest and HasFile() is true.
+func callMultipart[Resp any](ctx context.Context, b *Bot, method string, mp multipartRequest) (Resp, error) {
+	var zero Resp
+
+	pr, pw := io.Pipe()
+	mw := multipart.NewWriter(pw)
+
+	// Stream-write the multipart body in a goroutine so we don't buffer
+	// large files in memory.
+	go func() {
+		defer func() { _ = pw.Close() }()
+		defer func() { _ = mw.Close() }()
+		for k, v := range mp.MultipartFields() {
+			if err := mw.WriteField(k, v); err != nil {
+				_ = pw.CloseWithError(err)
+				return
+			}
+		}
+		for _, f := range mp.MultipartFiles() {
+			part, err := mw.CreateFormFile(f.FieldName, f.Filename)
+			if err != nil {
+				_ = pw.CloseWithError(err)
+				return
+			}
+			if _, err := io.Copy(part, f.Reader); err != nil {
+				_ = pw.CloseWithError(err)
+				return
+			}
+		}
+	}()
+
+	url := b.base + "/bot" + b.token + "/" + method
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, pr)
+	if err != nil {
+		_ = pr.CloseWithError(err)
+		return zero, &NetworkError{Err: err}
+	}
+	req.Header.Set("Content-Type", mw.FormDataContentType())
+	req.Header.Set("Accept", "application/json")
+
+	resp, err := b.http.Do(req)
+	if err != nil {
+		_ = pr.CloseWithError(err)
+		if ctxErr := ctx.Err(); ctxErr != nil {
+			return zero, ctxErr
+		}
+		return zero, &NetworkError{Err: err}
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	raw, err := io.ReadAll(resp.Body)
+	if err != nil {
+		_ = pr.CloseWithError(err)
+		return zero, &NetworkError{Err: err}
+	}
+	return decodeResult[Resp](b.codec, raw)
+}
+
+// callMultipartRaw is callMultipart's sibling that returns the raw result
+// JSON instead of decoding into a typed value. Used by generated method
+// wrappers whose return type is a sealed-interface union.
+func callMultipartRaw(ctx context.Context, b *Bot, method string, mp multipartRequest) (json.RawMessage, error) {
+	pr, pw := io.Pipe()
+	mw := multipart.NewWriter(pw)
+
+	go func() {
+		defer func() { _ = pw.Close() }()
+		defer func() { _ = mw.Close() }()
+		for k, v := range mp.MultipartFields() {
+			if err := mw.WriteField(k, v); err != nil {
+				_ = pw.CloseWithError(err)
+				return
+			}
+		}
+		for _, f := range mp.MultipartFiles() {
+			part, err := mw.CreateFormFile(f.FieldName, f.Filename)
+			if err != nil {
+				_ = pw.CloseWithError(err)
+				return
+			}
+			if _, err := io.Copy(part, f.Reader); err != nil {
+				_ = pw.CloseWithError(err)
+				return
+			}
+		}
+	}()
+
+	url := b.base + "/bot" + b.token + "/" + method
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, pr)
+	if err != nil {
+		_ = pr.CloseWithError(err)
+		return nil, &NetworkError{Err: err}
+	}
+	req.Header.Set("Content-Type", mw.FormDataContentType())
+	req.Header.Set("Accept", "application/json")
+
+	resp, err := b.http.Do(req)
+	if err != nil {
+		_ = pr.CloseWithError(err)
+		if ctxErr := ctx.Err(); ctxErr != nil {
+			return nil, ctxErr
+		}
+		return nil, &NetworkError{Err: err}
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	raw, err := io.ReadAll(resp.Body)
+	if err != nil {
+		_ = pr.CloseWithError(err)
+		return nil, &NetworkError{Err: err}
+	}
+	return decodeResultRaw(b.codec, raw)
+}