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

api/download.go

@@ -0,0 +1,57 @@
+package api
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/lukaszraczylo/go-telegram/client"
+)
+
+// DownloadFile fetches the contents of a Telegram-hosted file given a
+// previously-uploaded file_id. It calls GetFile to resolve the file's
+// download path, then issues an HTTP GET to the file CDN endpoint.
+//
+// The returned io.ReadCloser must be closed by the caller. The size of
+// the file is reported via *File.FileSize when known.
+//
+// For files larger than 20 MB, Telegram requires a self-hosted Bot API
+// server (default api.telegram.org has a 20 MB limit on getFile).
+func DownloadFile(ctx context.Context, b *client.Bot, fileID string) (io.ReadCloser, *File, error) {
+	f, err := GetFile(ctx, b, &GetFileParams{FileID: fileID})
+	if err != nil {
+		return nil, nil, fmt.Errorf("getFile: %w", err)
+	}
+	if f == nil || f.FilePath == "" {
+		return nil, f, fmt.Errorf("telegram: file %q has no download path", fileID)
+	}
+	rc, err := DownloadFileByPath(ctx, b, f.FilePath)
+	if err != nil {
+		return nil, f, err
+	}
+	return rc, f, nil
+}
+
+// DownloadFileByPath fetches a file by its file_path (typically obtained
+// from a prior File response). Useful when the caller already has a
+// *File and wants to skip the GetFile round-trip.
+func DownloadFileByPath(ctx context.Context, b *client.Bot, filePath string) (io.ReadCloser, error) {
+	url := fmt.Sprintf("%s/file/bot%s/%s", b.BaseURL(), b.Token(), filePath)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := b.HTTP().Do(req)
+	if err != nil {
+		if ctxErr := ctx.Err(); ctxErr != nil {
+			return nil, ctxErr
+		}
+		return nil, fmt.Errorf("download: %w", err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		_ = resp.Body.Close()
+		return nil, fmt.Errorf("download: HTTP %d", resp.StatusCode)
+	}
+	return resp.Body, nil
+}