fix: guard nil logger in prefix check

Document scene modal-chat flow and other missing core concepts in TODO.md
Require agent-created commits to be GPG-signed and fail fast if signing cannot complete

.gitignore

@@ -1,2 +1,5 @@
 .idea/
+.wiki/
+.vscode/
 test/
+.codex/

AGENTS.md

@@ -22,6 +22,18 @@ Review the codebase with focus on:
 - When feasible, make small, high-confidence improvements directly.
 - When uncertain, state confidence level and evidence.
 
+## Documentation languages
+- When creating or expanding project documentation, generate and maintain both English and Russian versions in the same turn whenever reasonably possible.
+- For wiki pages, prefer paired pages such as `Page.md` and `Page-RU.md`.
+- Keep English and Russian pages aligned in structure, major examples, and user-facing guidance.
+- If only one language can be updated safely in the current turn, explicitly say which language is lagging and why.
+
+## Wiki and backlog workflow
+- Treat the wiki as the primary place for large design ideas, architectural drafts, and framework backlog notes.
+- If the agent identifies a substantial new concept or design direction, such as scenes, callback agents, a webhook model, or another framework-level abstraction, the agent must ask the user whether it should also formalize that idea as a draft wiki page.
+- When the user agrees, prefer paired wiki pages such as `Page.md` and `Page-RU.md`, and clearly mark draft design pages with `DRAFT` when the API is not implemented or not yet stable.
+- Keep `TODO.md`, the wiki backlog pages, and `CHANGELOG.md` aligned when framework-level items move between planned and completed states.
+
 ## Go review expectations
 Check for:
 - bugs, fragile logic, invalid assumptions, nil handling issues, resource leaks;
@@ -76,6 +88,51 @@ Before finalizing changes, run the relevant project checks when available:
 
 Prefer the repository’s documented commands. If multiple choices exist, use the most standard and least destructive ones first.
 
+## Versioning and changelog
+- After every code or documentation change in the main repository, update `CHANGELOG.md`.
+- Changes made only inside the `.wiki/` repository do not require a `CHANGELOG.md` update.
+- Add changes only to the section for the next version after the latest published git tag.
+- The agent must check the latest published tag, `CHANGELOG.md`, and `utils/version.go` before editing the changelog.
+- The agent must verify that the target changelog version matches the version declared in `utils/version.go`.
+- If the latest published tag is, for example, `v1.0.0`, and `CHANGELOG.md` does not yet contain the next version section, the agent must stop and ask the user which version the change belongs to:
+  1. `v1.0.1`
+  2. `v1.1.0`
+  3. `v2.0.0`
+- The agent must not guess the next version when that section is missing.
+- If the user-selected version does not match `utils/version.go`, the agent must warn about the mismatch and require the version file to be updated before proceeding.
+- Changelog entries must describe all user-visible behavior changes made in the turn, including API additions, fixes, behavior changes, and breaking changes.
+- When a framework backlog item recorded in `TODO.md` is completed, the agent must also update the backlog status using the existing format:
+  1. move the completed item into the top of the `Done` section;
+  2. replace the numbered backlog label with a version tag, for example `1. Scene Model` becomes `[v2.0.0] Scene Model`;
+  3. keep the item title and descriptive notes aligned with the corresponding `CHANGELOG.md` entry.
+- The agent must treat `TODO.md` and `CHANGELOG.md` as linked records: a completed backlog item should not be left in one file as done and in the other as still pending or undocumented.
+
+## Breaking changes policy
+- The agent must detect potential breaking changes before editing public APIs.
+- Breaking changes are forbidden unless the selected target version is a new major version.
+- If the requested change is breaking and the user did not bump the major version, the agent must stop and warn that the change is not allowed under the current version.
+- In that case, the agent must offer only these options:
+  1. do not make the breaking change;
+  2. introduce a backward-compatible alternative such as a new method, function, type, or struct, but only if that keeps the codebase reasonably small and clear;
+  3. bump the major version and then apply the breaking change.
+- Prefer additive compatibility over signature changes when the additive option is small and maintainable.
+- Example: if a method like `ctx.answer(...)` needs an extra parameter, the agent must either require a major-version bump or add a new method that keeps the old method working.
+
+## Commit message format
+- When the user asks for a commit message, the agent must produce it in this format:
+  1. a short summary line;
+  2. up to three additional lines with only the most important changes;
+  3. each additional line must start on its own new line.
+- The agent must output the commit message as a plain multiline block that the user can copy directly.
+- Do not collapse the lines into a paragraph, bullet list, or wrapped prose explanation.
+- Keep commit text concise and high-signal.
+- Do not turn commit messages into changelogs.
+
+## Commit signing
+- All commits created by the agent must be GPG-signed.
+- If commit signing or pushing requires leaving the sandbox, the agent must request escalation explicitly before running the command.
+- If a signed commit cannot be created successfully, the agent must report the failure clearly and stop instead of creating an unsigned fallback commit.
+
 ## Output format
 For repo-wide review tasks, structure the result as:
 

CHANGELOG.md

@@ -1,6 +1,53 @@
 # Changelog
 
-## Unreleased
+## v1.0.0-rc.12
+
+### Added
+- `AnswerLong(...)`, `AnswerLongf(...)`, `KeyboardLong(...)`, and `SplitMessageText(...)` for explicit plain-text splitting of long replies without changing the semantics of existing single-message helpers.
+- Centralized library-level validation errors in `errors.go`, including `ErrEmptyMessage`, `ErrMessageTooLong`, `ErrCaptionTooLong`, and context/target validation sentinels.
+- `Bot.GetPayloadType()`, `InlineKeyboard.GetPayloadType()`, and optional strict payload decoding via `BotOpts.StrictPayloadType` / `Bot.SetStrictPayloadType(...)`.
+- `MsgContext.BindArgs(...)` for binding positional command arguments into exported struct fields.
+- Binding sentinels `ErrBindArgsTargetNotPointer`, `ErrBindArgsTargetNotStruct`, `ErrBindArgsUnsupportedFieldType`, and `ErrBindArgsConversion`.
+
+### Changed
+- `CommandExecutor` now returns `error`, and command, payload, and non-command update handlers now use centralized bot error handling for returned errors.
+- README and README_RU examples now use the new handler signature and document the long-message helpers.
+- README and README_RU now link to the project wiki, and the wiki now includes a page-priority tracker while content is being filled in.
+- `AGENTS.md` now requires every change to be recorded in `CHANGELOG.md`, enforces version alignment with `utils/version.go`, and blocks breaking changes without a major-version bump.
+- `AGENTS.md` now also defines a short commit-message format: one summary line plus up to three high-signal detail lines.
+- `AGENTS.md` now explicitly requires each commit-message detail line to be placed on its own new line.
+- `AGENTS.md` now also requires commit messages to be emitted as a plain multiline block instead of collapsed prose or list formatting.
+- `AGENTS.md` now requires new or expanded project documentation to be maintained in both English and Russian whenever reasonably possible.
+- `AGENTS.md` now requires all agent-created commits to be GPG-signed and to fail fast instead of falling back to unsigned commits when signing cannot be completed.
+- `AGENTS.md` now also links the wiki backlog flow more tightly to `TODO.md` and `CHANGELOG.md`, requiring draft-wiki confirmation for large new ideas and synchronized completion records for backlog items.
+- Added `TODO.md` to track missing framework-level concepts, with detailed notes for scenes, typed handler input, and request-scoped cancellation.
+- Payload-type comments and docs now distinguish between the bot's default payload type and keyboard-local overrides.
+- `MsgContext.Context()` now safely falls back to `context.Background()` when no request-scoped context is attached.
+- `MsgContext` reply, edit, callback, delete, action, and draft-limiter paths now use the context accessor instead of reaching into raw internal state.
+- `TODO.md` is now a short pointer file, while the detailed framework backlog lives in the wiki as `Framework-Backlog` / `Framework-Backlog-RU`.
+- Version constants were bumped to `v1.0.0-rc.12`.
+
+### Fixed
+- Message and caption validation now runs before Telegram API calls, rejecting empty messages, oversized message text, and oversized captions with stable sentinel errors.
+- Draft flushing and draft updates now reject oversized messages before sending invalid requests.
+- Callback payload decoding now optionally enforces strict type matching, while the default tolerant mode logs Base64-to-JSON decoding in debug mode and still accepts keyboard-local payload overrides.
+- Positional argument binding now leaves missing trailing struct fields at zero values, joins the remaining arguments into the final string field, and returns clearer binding errors.
+- Request-scoped contexts are now created per update handler execution and safely reused through `MsgContext.Context()` even for manually constructed test contexts.
+- Command and payload handlers now have regression coverage for end-to-end typed argument binding through the normal routing path.
+
+### Breaking Changes
+- `CommandExecutor[T]` changed from `func(ctx *MsgContext, db T)` to `func(ctx *MsgContext, db T) error`.
+- `Plugin.NewCommand(...)`, `Plugin.NewPayload(...)`, and `Plugin.AddUpdateHandler(...)` now require handlers with the new error-returning signature.
+
+### Tests
+- Added regression tests for `MsgContext.BindArgs(...)`, including scalar conversion, tail-string binding, zero-value trailing fields, invalid targets, unsupported field types, and end-to-end command/payload binding.
+
+## v1.0.0-rc.11
+
+### Fixed
+- `chat_boost` update decoding now accepts string `boost_id` values, matching the current Telegram Bot API schema and preventing polling failures on boosted-chat updates.
+
+## v1.0.0-rc.10
 
 ### Added
 - `Plugin.AddUpdateHandler` for routing non-command Telegram updates by `tgapi.UpdateType`.

README.md

@@ -10,6 +10,8 @@ A lightweight, easy-to-use, and performant Telegram Bot API wrapper for Go. It s
 
 [На русском](README_RU.md)
 
+[Wiki](https://git.nix13.pw/ScuroNeko/Laniakea/wiki)
+
 ---
 
 ## ✨ Features
@@ -52,10 +54,11 @@ import (
 // It receives two parameters:
 //   - ctx: the message context (contains info about the message, sender, chat, etc.)
 //   - db: your custom database context (here we use NoDB, a placeholder for no database)
-func echo(ctx *laniakea.MsgContext, db laniakea.NoDB) {
+func echo(ctx *laniakea.MsgContext, db laniakea.NoDB) error {
 	// Answer the user with the text they sent, without any command prefix.
 	// ctx.Text contains the user's message with the command part stripped off.
 	ctx.Answer(ctx.Text) // User input WITHOUT command
+	return nil
 }
 
 func main() {
@@ -81,8 +84,9 @@ func main() {
 
 	// 5. Add another command using an anonymous function (closure).
 	//    This command simply replies "Pong" when the user sends "/ping".
-	p.AddCommand(p.NewCommand(func(ctx *laniakea.MsgContext, db laniakea.NoDB) {
+	p.AddCommand(p.NewCommand(func(ctx *laniakea.MsgContext, db laniakea.NoDB) error {
 		ctx.Answer("Pong")
+		return nil
 	}, "ping"))
 
 	// 6. Configure the bot with a custom error template and add the plugin.
@@ -107,8 +111,8 @@ func main() {
 1. `BotOpts`: Holds configuration like the API token.
 2. `NewBot[T]`: Creates a bot instance. The type parameter T allows you to pass a custom database context (e.g., *sql.DB) that will be available in all handlers. Use laniakea.NoDB if you don't need it.
 3. `NewPlugin`: Creates a logical group for commands and middlewares.
-4. `AddCommand`: Registers a command. The first argument is the handler function (func(*MsgContext, T)), the second is the command name (without the slash).
+4. `AddCommand`: Registers a command. The first argument is the handler function (`func(*MsgContext, T) error`), the second is the command name (without the slash).
-5. **Handler Functions**: Receive *MsgContext (message details, methods like Answer) and your custom database context T.
+5. **Handler Functions**: Receive *MsgContext (message details, methods like Answer) and your custom database context T, and return an error for centralized error handling.
 6. `ErrorTemplate`: Sets a template for error messages. The %s placeholder is replaced by the actual error.
 7. `AutoGenerateCommands`: Registers plugin-defined commands with Telegram across the supported scopes.
 8. `Run()`: Starts the bot's update polling loop and returns an error if startup or polling fails.
@@ -128,9 +132,10 @@ bot.AddPlugins(plugin)
 
 A command is a function that handles a specific bot command (e.g., /start).
 ```go
-func myHandler(ctx *laniakea.MsgContext, db *MyDB) {
+func myHandler(ctx *laniakea.MsgContext, db *MyDB) error {
     // Access command arguments via ctx.Args ([]string)
     // Reply to the user: ctx.Answer("some text")
+    return nil
 }
 ```
 
@@ -139,8 +144,10 @@ func myHandler(ctx *laniakea.MsgContext, db *MyDB) {
 Provides access to the incoming message and useful reply methods:
 
 - `Answer(text string) *AnswerMessage`: Sends a message with parse_mode none.
+- `AnswerLong(text string) []*AnswerMessage`: Splits long plain text into multiple messages.
 - `AnswerMarkdown(text string) *AnswerMessage`: Sends a message formatted with MarkdownV2 (you handle escaping).
 - `Keyboard(text string, keyboard *InlineKeyboard) *AnswerMessage`: Sends a message with parse_mode none and inline keyboard.
+- `KeyboardLong(text string, keyboard *InlineKeyboard) []*AnswerMessage`: Splits long plain text into multiple messages and attaches the keyboard to the final chunk.
 - `KeyboardMarkdown(text string, keyboard *InlineKeyboard) *AnswerMessage`: Sends a message formatted with MarkdownV2 (you handle escaping) and inline keyboard.
 - `AnswerPhoto(photoId, text string) *AnswerMessage`: Sends a message with photo with parse_mode none.
 - `AnswerPhotoMarkdown(photoId, text string) *AnswerMessage`: Sends a photo with MarkdownV2 caption (you handle escaping).
@@ -223,7 +230,7 @@ func adminOnlyMiddleware(ctx *laniakea.MsgContext, db *MyDB) bool {
 - Middleware can modify the MsgContext (e.g., add custom fields) before the command runs.
 
 ## ⚙️ Advanced Configuration
-- **Inline Keyboards**: Build keyboards using `laniakea.NewInlineKeyboardJson`, `laniakea.NewInlineKeyboardBase64`, or `laniakea.NewInlineKeyboard`.
+- **Inline Keyboards**: Build keyboards using `laniakea.NewInlineKeyboardJson`, `laniakea.NewInlineKeyboardBase64`, or `laniakea.NewInlineKeyboard`. `Bot.SetPayloadType(...)` defines the default payload format, and `InlineKeyboard.SetPayloadType(...)` overrides it for one keyboard.
 - **Rate Limiting**: Pass a configured utils.RateLimiter via BotOpts to handle Telegram's rate limits gracefully.
 - **Localization**: `L10n` is safe for concurrent use once attached to the bot.
 - **Custom Update Handlers**: Use `plugin.AddUpdateHandler(...)` for Telegram update types that are not part of the command/payload flow.
@@ -242,6 +249,8 @@ This project is licensed under the GNU General Public License v3.0 — see the [
 ## 📚 Learn More
 [GoDoc](https://pkg.go.dev/git.nix13.pw/scuroneko/laniakea)
 
+[Wiki](https://git.nix13.pw/ScuroNeko/Laniakea/wiki)
+
 [Telegram Bot API](https://core.telegram.org/bots/api)
 
     ✅ Built with ❤️ by scuroneko

README_RU.md

@@ -10,6 +10,8 @@
 
 [English](README.md)
 
+[Wiki](https://git.nix13.pw/ScuroNeko/Laniakea/wiki)
+
 ---
 
 ## ✨ Возможности
@@ -53,10 +55,11 @@ import (
 // Она получает два параметра:
 //   - ctx: контекст сообщения (содержит информацию о сообщении, отправителе, чате и т.д.)
 //   - db: ваш пользовательский контекст базы данных (здесь мы используем NoDB — заглушку)
-func echo(ctx *laniakea.MsgContext, db laniakea.NoDB) {
+func echo(ctx *laniakea.MsgContext, db laniakea.NoDB) error {
 	// Отвечаем пользователю текстом, который он прислал, без префикса команды.
 	// ctx.Text содержит сообщение пользователя, из которого удалена часть с командой.
 	ctx.Answer(ctx.Text) // Ввод пользователя БЕЗ команды
+	return nil
 }
 
 func main() {
@@ -82,8 +85,9 @@ func main() {
 
 	// 5. Добавляем ещё одну команду, используя анонимную функцию (замыкание).
 	//    Эта команда просто отвечает "Pong", когда пользователь отправляет "/ping".
-	p.AddCommand(p.NewCommand(func(ctx *laniakea.MsgContext, db laniakea.NoDB) {
+	p.AddCommand(p.NewCommand(func(ctx *laniakea.MsgContext, db laniakea.NoDB) error {
 		ctx.Answer("Pong")
+		return nil
 	}, "ping"))
 
 	// 6. Настраиваем бота: задаём шаблон ошибки и добавляем плагин.
@@ -108,8 +112,8 @@ func main() {
 1. `BotOpts`: Содержит конфигурацию, например, токен API.
 2. `NewBot[T]`: Создаёт экземпляр бота. Параметр типа T позволяет передать пользовательский контекст базы данных (например, *sql.DB), который будет доступен во всех обработчиках. Используйте laniakea.NoDB, если он не нужен.
 3. `NewPlugin`: Создаёт логическую группу для команд и Middleware.
-4. `AddCommand`: Регистрирует команду. Первый аргумент — функция-обработчик (func(*MsgContext, T)), второй — имя команды (без слеша).
+4. `AddCommand`: Регистрирует команду. Первый аргумент — функция-обработчик (`func(*MsgContext, T) error`), второй — имя команды (без слеша).
-5. **Функции-обработчики**: Получают *MsgContext (детали сообщения, методы типа Answer) и ваш контекст базы данных T.
+5. **Функции-обработчики**: Получают *MsgContext (детали сообщения, методы типа Answer) и ваш контекст базы данных T, а ошибку возвращают для централизованной обработки.
 6. `ErrorTemplate`: Устанавливает шаблон для сообщений об ошибках. Плейсхолдер %s заменяется на текст ошибки.
 7. `AutoGenerateCommands`: Регистрирует команды из плагинов в Telegram для поддерживаемых scope.
 8. `Run()`: Запускает цикл опроса обновлений бота и возвращает ошибку, если старт или polling завершился неуспешно.
@@ -129,9 +133,10 @@ bot.AddPlugins(plugin)
 Команда — это функция, которая обрабатывает конкретную команду бота (например, /start).
 
 ```go
-func myHandler(ctx *laniakea.MsgContext, db *MyDB) {
+func myHandler(ctx *laniakea.MsgContext, db *MyDB) error {
     // Доступ к аргументам команды через ctx.Args ([]string)
     // Ответ пользователю: ctx.Answer("какой-то текст")
+    return nil
 }
 ```
 
@@ -139,8 +144,10 @@ func myHandler(ctx *laniakea.MsgContext, db *MyDB) {
 Предоставляет доступ к входящему сообщению и полезные методы для ответа:
 
 - `Answer(text string)`: Отправляет сообщение с parse_mode none.
+- `AnswerLong(text string) []*AnswerMessage`: Разбивает длинный plain text на несколько сообщений.
 - `AnswerMarkdown(text string)`: Отправляет сообщение, отформатированное MarkdownV2 (экранирование на вашей стороне).
 - `Keyboard(text string, keyboard *InlineKeyboard) *AnswerMessage`: Отправляет сообщение с parse_mode none и Inline клавиатурой.
+- `KeyboardLong(text string, keyboard *InlineKeyboard) []*AnswerMessage`: Разбивает длинный plain text на несколько сообщений и вешает клавиатуру на последний chunk.
 - `KeyboardMarkdown(text string, keyboard *InlineKeyboard) *AnswerMessage`: Отправляет сообщение, отформатированное MarkdownV2 (экранирование на вашей стороне), и Inline клавиатурой.
 - `AnswerPhoto(photoId, text string) *AnswerMessage`: Отправляет фотографию с подписью и parse_mode none.
 - `AnswerPhotoMarkdown(photoId, text string) *AnswerMessage`: Отправляет фотографию с подписью, отформатированной MarkdownV2 (экранирование на вашей стороне).
@@ -220,7 +227,7 @@ func adminOnlyMiddleware(ctx *laniakea.MsgContext, db *MyDB) bool {
 - Middleware может изменять MsgContext (например, добавлять пользовательские поля) перед запуском команды.
 
 ## ⚙️ Расширенная настройка
-- **Инлайн-клавиатуры**: Создавайте клавиатуры с помощью `laniakea.NewInlineKeyboardJson`, `laniakea.NewInlineKeyboardBase64` или `laniakea.NewInlineKeyboard`.
+- **Инлайн-клавиатуры**: Создавайте клавиатуры с помощью `laniakea.NewInlineKeyboardJson`, `laniakea.NewInlineKeyboardBase64` или `laniakea.NewInlineKeyboard`. `Bot.SetPayloadType(...)` задаёт payload format по умолчанию, а `InlineKeyboard.SetPayloadType(...)` переопределяет его для конкретной клавиатуры.
 - **Ограничение запросов**: Передайте настроенный `utils.RateLimiter` через `BotOpts` для корректной обработки лимитов Telegram.
 - **Локализация**: `L10n` безопасен для конкурентного использования после подключения к боту.
 - **Пользовательские update handlers**: Используйте `plugin.AddUpdateHandler(...)` для Telegram update types вне command/payload flow.
@@ -238,6 +245,8 @@ func adminOnlyMiddleware(ctx *laniakea.MsgContext, db *MyDB) bool {
 ## 📚 Дополнительная информация
 [GoDoc Laniakea](https://pkg.go.dev/git.nix13.pw/scuroneko/laniakea)
 
+[Wiki](https://git.nix13.pw/ScuroNeko/Laniakea/wiki)
+
 [Telegram Bot API](https://core.telegram.org/bots/api)
 
     ✅ Создано с ❤️ scuroneko

TODO.md

@@ -0,0 +1,17 @@
+# TODO
+
+The framework backlog has moved to the wiki.
+
+Primary page:
+
+- https://git.nix13.pw/ScuroNeko/Laniakea/wiki/Framework-Backlog
+
+Russian page:
+
+- https://git.nix13.pw/ScuroNeko/Laniakea/wiki/Framework-Backlog-RU
+
+Current high-priority status:
+
+- `1. Conversation / Scene Model`: not implemented yet.
+- `2. Typed Handler Input Model`: completed in `v1.0.0-rc.12`.
+- `3. Request Context / Cancellation Model`: completed in `v1.0.0-rc.12`.

bot.go

@@ -4,7 +4,9 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"maps"
 	"reflect"
+	"slices"
 	"sort"
 	"strings"
 	"sync"
@@ -77,12 +79,13 @@ var (
 // Runtime accessors are safe for concurrent use. Configure the bot before Run.
 // A Bot is single-use: after Run or RunWithContext returns, create a new Bot for the next session.
 type Bot[T DbContext] struct {
-	token         string
+	token             string
-	debug         bool
+	debug             bool
-	errorTemplate string
+	errorTemplate     string
-	username      string
+	username          string
-	payloadType   BotPayloadType
+	payloadType       BotPayloadType
-	maxWorkers    int
+	strictPayloadType bool
+	maxWorkers        int
 
 	logger        *slog.Logger                // Main bot logger (JSON stdout + optional file)
 	RequestLogger *slog.Logger                // Optional request-level API logging
@@ -101,6 +104,9 @@ type Bot[T DbContext] struct {
 	l10n          *L10n          // Localization manager
 	draftProvider *DraftProvider // Draft message builder
 
+	sessionStore       SessionStore // Session store for scene management
+	sceneScopePriority []SceneScope
+
 	updateOffsetMu sync.Mutex
 	updateOffset   int                // Last processed update ID
 	updateTypes    []tgapi.UpdateType // Types of updates to fetch
@@ -156,22 +162,26 @@ func NewBot[T any](opts *BotOpts) (*Bot[T], error) {
 	}
 
 	bot := &Bot[T]{
-		updateOffset:  0,
+		updateOffset:      0,
-		errorTemplate: "%s",
+		errorTemplate:     "%s",
-		payloadType:   BotPayloadBase64,
+		payloadType:       BotPayloadBase64,
-		maxWorkers:    workers,
+		strictPayloadType: opts.StrictPayloadType,
-		updateQueue:   updateQueue,
+		maxWorkers:        workers,
-		api:           api,
+		updateQueue:       updateQueue,
-		uploader:      uploader,
+		api:               api,
-		debug:         opts.Debug,
+		uploader:          uploader,
-		prefixes:      prefixes,
+		debug:             opts.Debug,
-		token:         opts.Token,
+		prefixes:          prefixes,
-		plugins:       make([]Plugin[T], 0),
+		token:             opts.Token,
-		updateTypes:   append([]tgapi.UpdateType{}, opts.UpdateTypes...),
+		plugins:           make([]Plugin[T], 0),
-		runners:       make([]Runner[T], 0),
+		updateTypes:       append([]tgapi.UpdateType{}, opts.UpdateTypes...),
-		extraLoggers:  make([]*slog.Logger, 0),
+		runners:           make([]Runner[T], 0),
-		l10n:          &L10n{},
+		extraLoggers:      make([]*slog.Logger, 0),
-		draftProvider: NewRandomDraftProvider(api),
+		l10n:              &L10n{},
+		draftProvider:     NewRandomDraftProvider(api),
+
+		sessionStore:       NewMemorySessionStore(),
+		sceneScopePriority: []SceneScope{SceneScopeUserChat, SceneScopeChat, SceneScopeUser},
 	}
 
 	// Add API and Uploader loggers to extraLoggers for unified output
@@ -332,6 +342,34 @@ func (bot *Bot[T]) SetDraftProvider(p *DraftProvider) *Bot[T] {
 	bot.draftProvider = p
 	return bot
 }
+func (bot *Bot[T]) GetDraftProvider() *DraftProvider {
+	return bot.draftProvider
+}
+
+func (bot *Bot[T]) SetSettionStore(store SessionStore) *Bot[T] {
+	bot.sessionStore = store
+	return bot
+}
+func (bot *Bot[T]) GetSessionStore() SessionStore {
+	return bot.sessionStore
+}
+
+func (bot *Bot[T]) SetSceneScopePriority(priority []SceneScope) *Bot[T] {
+	newPriority := make([]SceneScope, 0, 3)
+	for _, scope := range priority {
+		if slices.Index(newPriority, scope) >= 0 {
+			bot.logger.Warnln(fmt.Sprintf("duplicate scope %v in scene scope priority; ignoring duplicates", scope))
+			continue
+		}
+		newPriority = append(newPriority, scope)
+	}
+	if len(newPriority) == 0 || len(newPriority) > 3 {
+		bot.logger.Warnln("scene scope priority must have 1 to 3 scopes; ignoring invalid input")
+		return bot
+	}
+	bot.sceneScopePriority = append([]SceneScope(nil), newPriority...)
+	return bot
+}
 
 // DatabaseContext injects a database context into the bot.
 // This context is accessible to plugins and middleware via GetDBContext().
@@ -356,14 +394,25 @@ func (bot *Bot[T]) UpdateTypes(t ...tgapi.UpdateType) *Bot[T] {
 	return bot
 }
 
-// SetPayloadType sets the payload encoding type used for callback data.
+// SetPayloadType sets the default payload encoding type used for callback data.
 // JSON stores payload as a string: `{"cmd":"command","args":[...]}`.
 // Base64 stores the same JSON encoded as a Base64URL string.
+// InlineKeyboard.SetPayloadType may override this value for an individual keyboard.
 func (bot *Bot[T]) SetPayloadType(t BotPayloadType) *Bot[T] {
 	bot.payloadType = t
 	return bot
 }
 
+// GetPayloadType returns the bot's default callback payload encoding type.
+func (bot *Bot[T]) GetPayloadType() BotPayloadType { return bot.payloadType }
+
+// SetStrictPayloadType enables or disables strict callback payload decoding.
+// When enabled, callback payloads must match the bot's default payload type.
+func (bot *Bot[T]) SetStrictPayloadType(strict bool) *Bot[T] {
+	bot.strictPayloadType = strict
+	return bot
+}
+
 // AddUpdateType adds one or more update types to the list.
 // Does not overwrite existing types.
 func (bot *Bot[T]) AddUpdateType(t ...tgapi.UpdateType) *Bot[T] {
@@ -655,7 +704,7 @@ func (bot *Bot[T]) RunWithContext(ctx context.Context) error {
 	for update := range bot.updateQueue {
 		u := update // capture loop variable
 		pool.Submit(func() {
-			bot.handle(u)
+			bot.handle(ctx, u)
 		})
 	}
 	pool.Stop() // Wait for all tasks to complete and stop the pool
@@ -746,9 +795,7 @@ func clonePlugin[T DbContext](p *Plugin[T]) Plugin[T] {
 	for name, command := range p.payloads {
 		cloned.payloads[name] = cloneCommand(command)
 	}
-	for t, handler := range p.handlers {
+	maps.Copy(cloned.handlers, p.handlers)
-		cloned.handlers[t] = handler
-	}
 
 	return cloned
 }

bot_opts.go

@@ -56,6 +56,10 @@ type BotOpts struct {
 	// Use this to prioritize responsiveness over reliability.
 	DropRLOverflow bool
 
+	// StrictPayloadType disables callback payload fallback decoding.
+	// When enabled, the bot accepts only the configured default payload type.
+	StrictPayloadType bool
+
 	// MaxWorkers is the maximum number of update handlers that may run concurrently.
 	MaxWorkers int
 }
@@ -75,6 +79,7 @@ type BotOpts struct {
 //   - API_URL: custom API endpoint
 //   - RATE_LIMIT: max requests per second (default: 30)
 //   - DROP_RL_OVERFLOW: "true" to drop updates on rate limit overflow
+//   - STRICT_PAYLOAD_TYPE: "true" to reject callback payloads encoded in a different format
 //   - MAX_WORKERS: maximum number of concurrent update handlers (default: 32)
 //
 // Returns a populated BotOpts.
@@ -116,8 +121,9 @@ func LoadOptsFromEnv() *BotOpts {
 		UseTestServer: os.Getenv("USE_TEST_SERVER") == "true",
 		APIUrl:        os.Getenv("API_URL"),
 
-		RateLimit:      rateLimit,
+		RateLimit:         rateLimit,
-		DropRLOverflow: os.Getenv("DROP_RL_OVERFLOW") == "true",
+		DropRLOverflow:    os.Getenv("DROP_RL_OVERFLOW") == "true",
+		StrictPayloadType: os.Getenv("STRICT_PAYLOAD_TYPE") == "true",
 
 		MaxWorkers: maxWorkers,
 	}
@@ -208,6 +214,13 @@ func (opts *BotOpts) SetDropRLOverflow(drop bool) *BotOpts {
 	return opts
 }
 
+// SetStrictPayloadType enables or disables strict callback payload decoding.
+// When enabled, the bot accepts only the configured default payload type.
+func (opts *BotOpts) SetStrictPayloadType(strict bool) *BotOpts {
+	opts.StrictPayloadType = strict
+	return opts
+}
+
 // SetMaxWorkers sets the maximum number of concurrent update handlers.
 // Must be called before NewBot, as the value is captured during bot creation.
 //

bot_opts_test.go

@@ -45,3 +45,12 @@ func TestLoadPrefixesFromEnvDropsEmptyValues(t *testing.T) {
 		t.Fatalf("unexpected prefixes: got %v want %v", got, want)
 	}
 }
+
+func TestLoadOptsFromEnvReadsStrictPayloadType(t *testing.T) {
+	t.Setenv("STRICT_PAYLOAD_TYPE", "true")
+
+	opts := LoadOptsFromEnv()
+	if !opts.StrictPayloadType {
+		t.Fatal("expected StrictPayloadType to be enabled")
+	}
+}

bot_scene.go

@@ -0,0 +1,61 @@
+package laniakea
+
+func (bot *Bot[T]) GetSession(key string) (SceneSession, error) {
+	return bot.sessionStore.Get(key)
+}
+
+func (bot *Bot[T]) SetSession(key string, session SceneSession) error {
+	return bot.sessionStore.Set(key, session)
+}
+
+func (bot *Bot[T]) DeleteSession(key string) error {
+	return bot.sessionStore.Delete(key)
+}
+func (bot *Bot[T]) FindScene(name string) (*sceneMeta, bool) {
+	for _, plugin := range bot.plugins {
+		scene, ok := plugin.scenes[name]
+		if !ok {
+			continue
+		}
+
+		steps := make(map[string]struct{}, len(scene.steps))
+		for step := range scene.steps {
+			steps[step] = struct{}{}
+		}
+
+		return &sceneMeta{
+			Name:  scene.Name,
+			Scope: scene.Scope,
+			Entry: scene.Entry,
+			Steps: steps,
+		}, true
+	}
+	return nil, false
+}
+
+func (bot *Bot[T]) FindSceneSession(ctx *MsgContext) (string, SceneSession, error) {
+	var zero SceneSession
+	if ctx.Msg == nil {
+		return "", zero, ErrMessageNil
+	}
+
+	for _, scope := range bot.sceneScopePriority {
+		key, ok := buildSceneKey(scope, ctx)
+		if !ok {
+			continue
+		}
+
+		session, err := bot.sessionStore.Get(key)
+		if err != nil {
+			return "", zero, err
+		}
+		if session.Scene != "" {
+			return key, session, nil
+		}
+	}
+
+	return "", zero, ErrCantFindSession
+}
+func (bot *Bot[T]) BuildSceneKey(scope SceneScope, ctx *MsgContext) (string, bool) {
+	return buildSceneKey(scope, ctx)
+}

bot_test.go

@@ -27,13 +27,13 @@ func TestAddPluginsSnapshotsConfiguration(t *testing.T) {
 	bot := &Bot[NoDB]{logger: slog.CreateLogger()}
 	plugin := NewPlugin[NoDB]("demo")
 
-	cmd := plugin.NewCommand(func(ctx *MsgContext, db NoDB) {}, "start")
+	cmd := plugin.NewCommand(func(ctx *MsgContext, db NoDB) error { return nil }, "start")
 	plugin.AddMiddleware(NewMiddleware("base", func(ctx *MsgContext, db NoDB) bool { return true }))
 
 	bot.AddPlugins(plugin)
 
 	cmd.SetDescription("mutated after registration")
-	plugin.NewCommand(func(ctx *MsgContext, db NoDB) {}, "late")
+	plugin.NewCommand(func(ctx *MsgContext, db NoDB) error { return nil }, "late")
 	plugin.AddMiddleware(NewMiddleware("late", func(ctx *MsgContext, db NoDB) bool { return true }))
 
 	registered := bot.plugins[0]
@@ -48,6 +48,22 @@ func TestAddPluginsSnapshotsConfiguration(t *testing.T) {
 	}
 }
 
+func TestBotPayloadTypeConfiguration(t *testing.T) {
+	bot := &Bot[NoDB]{payloadType: BotPayloadBase64}
+
+	if got := bot.GetPayloadType(); got != BotPayloadBase64 {
+		t.Fatalf("unexpected initial payload type: %q", got)
+	}
+	bot.SetPayloadType(BotPayloadJson)
+	if got := bot.GetPayloadType(); got != BotPayloadJson {
+		t.Fatalf("unexpected updated payload type: %q", got)
+	}
+	bot.SetStrictPayloadType(true)
+	if !bot.strictPayloadType {
+		t.Fatal("expected strict payload type to be enabled")
+	}
+}
+
 func TestAddPluginsSkipsNilPlugin(t *testing.T) {
 	bot := &Bot[NoDB]{logger: slog.CreateLogger()}
 	plugin := NewPlugin[NoDB]("demo")

cmd_generator_test.go

@@ -44,7 +44,7 @@ func TestAutoGenerateCommandsChecksLimitBeforeDelete(t *testing.T) {
 	}()
 
 	plugin := NewPlugin[NoDB]("overflow")
-	exec := func(ctx *MsgContext, db NoDB) {}
+	exec := func(ctx *MsgContext, db NoDB) error { return nil }
 	for i := 0; i < 101; i++ {
 		plugin.AddCommand(NewCommand(exec, "cmd"+strconv.Itoa(i)))
 	}
@@ -66,7 +66,7 @@ func TestAutoGenerateCommandsChecksLimitBeforeDelete(t *testing.T) {
 
 func TestGatherCommandsForPluginReturnsSortedCommands(t *testing.T) {
 	plugin := NewPlugin[NoDB]("sorted")
-	exec := func(ctx *MsgContext, db NoDB) {}
+	exec := func(ctx *MsgContext, db NoDB) error { return nil }
 
 	plugin.AddCommand(NewCommand(exec, "zeta"))
 	plugin.AddCommand(NewCommand(exec, "alpha"))

drafts.go

@@ -1,7 +1,6 @@
 package laniakea
 
 import (
-	"errors"
 	"math/rand/v2"
 	"sync"
 	"sync/atomic"
@@ -9,9 +8,6 @@ import (
 	"git.nix13.pw/scuroneko/laniakea/tgapi"
 )
 
-// ErrDraftChatIDZero is returned when a draft is used without setting a chat ID.
-var ErrDraftChatIDZero = errors.New("zero draft chat ID")
-
 // Interface for generating unique draft IDs.
 type draftIdGenerator interface {
 	// Next returns the next unique draft ID.
@@ -221,6 +217,9 @@ func (d *Draft) Flush() error {
 	if d.chatID == 0 {
 		return ErrDraftChatIDZero
 	}
+	if err := validateMessageText(d.Message); err != nil {
+		return err
+	}
 
 	params := tgapi.SendMessageP{
 		ChatID:    d.chatID,
@@ -245,6 +244,9 @@ func (d *Draft) push(text string) error {
 		return ErrDraftChatIDZero
 	}
 	d.Message += text
+	if err := validateMessageText(d.Message); err != nil {
+		return err
+	}
 	params := tgapi.SendMessageDraftP{
 		ChatID:    d.chatID,
 		DraftID:   d.ID,

drafts_test.go

@@ -1,6 +1,8 @@
 package laniakea
 
 import (
+	"errors"
+	"strings"
 	"testing"
 
 	"git.nix13.pw/scuroneko/laniakea/tgapi"
@@ -34,3 +36,20 @@ func TestMsgContextNewDraftWorksWithoutLimiter(t *testing.T) {
 		t.Fatalf("unexpected chat id: %d", draft.chatID)
 	}
 }
+
+func TestDraftFlushRejectsLongMessage(t *testing.T) {
+	draft := NewRandomDraftProvider(&tgapi.API{}).NewDraft(tgapi.ParseNone).SetChat(42, 0)
+	draft.Message = strings.Repeat("a", maxMessageTextLen+1)
+
+	if err := draft.Flush(); !errors.Is(err, ErrMessageTooLong) {
+		t.Fatalf("expected ErrMessageTooLong, got %v", err)
+	}
+}
+
+func TestDraftPushRejectsLongMessage(t *testing.T) {
+	draft := NewRandomDraftProvider(&tgapi.API{}).NewDraft(tgapi.ParseNone).SetChat(42, 0)
+
+	if err := draft.Push(strings.Repeat("a", maxMessageTextLen+1)); !errors.Is(err, ErrMessageTooLong) {
+		t.Fatalf("expected ErrMessageTooLong, got %v", err)
+	}
+}

errors.go

@@ -0,0 +1,73 @@
+package laniakea
+
+import (
+	"errors"
+	"fmt"
+	"unicode/utf8"
+)
+
+const (
+	maxMessageTextLen    = 4096
+	maxMessageCaptionLen = 1024
+)
+
+var (
+	// ErrEmptyMessage reports that a required message text is empty.
+	ErrEmptyMessage = errors.New("empty message")
+	// ErrMessageTooLong reports that a message exceeds Telegram's text limit.
+	ErrMessageTooLong = errors.New("message too long")
+	// ErrCaptionTooLong reports that a caption exceeds Telegram's caption limit.
+	ErrCaptionTooLong = errors.New("caption too long")
+	// ErrMessageSplitImpossible reports that automatic message splitting cannot preserve semantics.
+	ErrMessageSplitImpossible = errors.New("message split is impossible")
+	// ErrPayloadTypeMismatch reports that callback payload encoding does not match bot policy.
+	ErrPayloadTypeMismatch = errors.New("payload type mismatch")
+	// ErrDraftChatIDZero reports that a draft has no target chat ID.
+	ErrDraftChatIDZero = errors.New("zero draft chat ID")
+	ErrMessageNil      = errors.New("message is nil")
+	// ErrMessageContextNil reports that an operation requires ctx.Msg but none is set.
+	ErrMessageContextNil = errors.New("message context is nil")
+	// ErrEditTargetMissing reports that an edit operation has no message target.
+	ErrEditTargetMissing = errors.New("edit target is missing")
+	// ErrCallbackMessageMissing reports that a callback operation has no callback message target.
+	ErrCallbackMessageMissing = errors.New("callback message is missing")
+	// ErrDraftProviderNil reports that draft creation was requested without a draft provider.
+	ErrDraftProviderNil = errors.New("draft provider is nil")
+	// ErrAPIIsNil reports that an operation requires an API client but none is set.
+	ErrAPIIsNil = errors.New("api is nil")
+	// ErrMessageIDZero reports that an operation requires a non-zero message ID.
+	ErrMessageIDZero = errors.New("message ID is zero")
+	// ErrBindArgsTargetNotPointer reports that BindArgs received a nil or non-pointer destination.
+	ErrBindArgsTargetNotPointer = errors.New("bind args: dst must be a non-nil pointer")
+	// ErrBindArgsTargetNotStruct reports that BindArgs received a pointer to a non-struct value.
+	ErrBindArgsTargetNotStruct = errors.New("bind args: dst must point to a struct")
+	// ErrBindArgsUnsupportedFieldType reports that BindArgs encountered an unsupported field kind.
+	ErrBindArgsUnsupportedFieldType = errors.New("bind args: unsupported field type")
+	// ErrBindArgsConversion reports that BindArgs could not convert a string argument into a field type.
+	ErrBindArgsConversion   = errors.New("bind args: conversion failed")
+	ErrCantFindSession      = errors.New("can't find session for this context")
+	ErrSceneNotFound        = errors.New("scene not found")
+	ErrSceneStepNotFound    = errors.New("scene step not found")
+	ErrSceneCommandNotFound = errors.New("scene command not found")
+	ErrNotInScene           = errors.New("not in scene")
+)
+
+func validateMessageText(text string) error {
+	length := utf8.RuneCountInString(text)
+	switch {
+	case length == 0:
+		return ErrEmptyMessage
+	case length > maxMessageTextLen:
+		return fmt.Errorf("%w: got %d, limit %d", ErrMessageTooLong, length, maxMessageTextLen)
+	default:
+		return nil
+	}
+}
+
+func validateCaptionText(text string) error {
+	length := utf8.RuneCountInString(text)
+	if length > maxMessageCaptionLen {
+		return fmt.Errorf("%w: got %d, limit %d", ErrCaptionTooLong, length, maxMessageCaptionLen)
+	}
+	return nil
+}

handler.go

@@ -1,6 +1,7 @@
 package laniakea
 
 import (
+	"context"
 	"encoding/base64"
 	"encoding/json"
 	"errors"
@@ -13,36 +14,50 @@ import (
 // ErrInvalidPayloadType is returned when callback payload encoding type is unknown.
 var ErrInvalidPayloadType = errors.New("invalid payload type")
 
-func (bot *Bot[T]) handle(u *tgapi.Update) {
+func (bot *Bot[T]) handle(parentCtx context.Context, u *tgapi.Update) {
 	defer func() {
 		if r := recover(); r != nil {
 			bot.logger.Errorln(fmt.Sprintf("panic in handle: %v", r))
 		}
 	}()
 
-	ctx := &MsgContext{
+	ctx, cancel := context.WithCancel(parentCtx)
+	defer cancel()
+
+	msgCtx := &MsgContext{
 		Update: *u, Api: bot.api,
 		Logger:        bot.logger,
 		errorTemplate: bot.errorTemplate,
 		l10n:          bot.l10n,
 		draftProvider: bot.draftProvider,
+		sceneRuntime:  bot,
 		payloadType:   bot.payloadType,
+		ctx:           ctx,
 	}
-	bot.prepareUpdateCtx(u, ctx)
+	bot.prepareUpdateCtx(u, msgCtx)
 
 	for _, middleware := range bot.middlewares {
-		if !middleware.Execute(ctx, bot.dbContext) {
+		if !middleware.Execute(msgCtx, bot.dbContext) {
 			return
 		}
 	}
 
+	sceneHandled, err := bot.tryHandleScene(msgCtx)
+	if err != nil {
+		bot.logger.Errorln(err)
+		return
+	}
+	if sceneHandled {
+		return
+	}
+
 	switch u.Type {
 	case tgapi.UpdateTypeMessage, tgapi.UpdateTypeChannelPost:
-		bot.handleMessage(u, ctx)
+		bot.handleMessage(u, msgCtx)
 	case tgapi.UpdateTypeCallbackQuery:
-		bot.handleCallback(u, ctx)
+		bot.handleCallback(u, msgCtx)
 	default:
-		bot.handleUpdate(u, ctx)
+		bot.handleUpdate(u, msgCtx)
 	}
 }
 
@@ -65,30 +80,11 @@ func (bot *Bot[T]) handleMessage(update *tgapi.Update, ctx *MsgContext) {
 		return
 	}
 
-	text = strings.TrimSpace(text)
+	prefix, cmd, args := bot.parseCommand(text)
-	prefix, hasPrefix := bot.checkPrefixes(text)
+	if cmd == "" {
-	if !hasPrefix {
 		return
 	}
-
 	ctx.Prefix = prefix
-	ctx.Update = *update
-
-	// Убираем префикс
-	text = strings.TrimSpace(text[len(prefix):])
-
-	// Извлекаем команду как первое слово
-	spaceIndex := strings.Index(text, " ")
-	var cmd string
-	var args string
-
-	if spaceIndex == -1 {
-		cmd = text
-		args = ""
-	} else {
-		cmd = text[:spaceIndex]
-		args = strings.TrimSpace(text[spaceIndex:])
-	}
 
 	if strings.Contains(cmd, "@") {
 		botUsername := bot.username
@@ -156,7 +152,9 @@ func (bot *Bot[T]) handleUpdate(u *tgapi.Update, ctx *MsgContext) {
 		if !plugin.executeMiddlewares(pluginCtx, bot.dbContext) {
 			continue
 		}
-		handler(pluginCtx, bot.dbContext)
+		if err := handler(pluginCtx, bot.dbContext); err != nil {
+			pluginCtx.error(err)
+		}
 	}
 }
 
@@ -267,12 +265,14 @@ func (bot *Bot[T]) prepareUpdateCtx(u *tgapi.Update, ctx *MsgContext) {
 		ctx.From = from
 		ctx.FromID = from.ID
 	}
-	ctx.Update = *u
 }
 
 func (bot *Bot[T]) checkPrefixes(text string) (string, bool) {
 	for _, prefix := range bot.prefixes {
 		if prefix == "" {
+			if bot.logger != nil {
+				bot.logger.Warnln("empty prefix is not allowed")
+			}
 			continue
 		}
 		if strings.HasPrefix(text, prefix) {
@@ -281,6 +281,23 @@ func (bot *Bot[T]) checkPrefixes(text string) (string, bool) {
 	}
 	return "", false
 }
+func (bot *Bot[T]) parseCommand(text string) (prefix, cmd, args string) {
+	if prefix, hasPrefix := bot.checkPrefixes(text); hasPrefix {
+		text = strings.TrimSpace(text[len(prefix):])
+		spaceIndex := strings.Index(text, " ")
+		var cmd string
+		var args string
+		if spaceIndex == -1 {
+			cmd = text
+			args = ""
+		} else {
+			cmd = text[:spaceIndex]
+			args = strings.TrimSpace(text[spaceIndex:])
+		}
+		return prefix, cmd, args
+	}
+	return "", "", ""
+}
 
 func encodeJsonPayload(d CallbackData) (string, error) {
 	b, err := json.Marshal(d)
@@ -320,19 +337,48 @@ func decodeBase64Payload(s string) (CallbackData, error) {
 	}
 	return decodeJsonPayload(string(b))
 }
-func decodePayload(payloadType BotPayloadType, s string) (CallbackData, error) {
+func decodePayload(payloadType BotPayloadType, s string, strict bool) (CallbackData, BotPayloadType, error) {
 	switch payloadType {
 	case BotPayloadBase64:
-		return decodeBase64Payload(s)
+		data, err := decodeBase64Payload(s)
+		if err == nil {
+			return data, BotPayloadBase64, nil
+		}
+		if strict {
+			return CallbackData{}, "", fmt.Errorf("%w: expected %s", ErrPayloadTypeMismatch, BotPayloadBase64)
+		}
+		data, err = decodeJsonPayload(s)
+		if err != nil {
+			return CallbackData{}, "", err
+		}
+		return data, BotPayloadJson, nil
 	case BotPayloadJson:
-		return decodeJsonPayload(s)
+		data, err := decodeJsonPayload(s)
+		if err == nil {
+			return data, BotPayloadJson, nil
+		}
+		if strict {
+			return CallbackData{}, "", fmt.Errorf("%w: expected %s", ErrPayloadTypeMismatch, BotPayloadJson)
+		}
+		data, err = decodeBase64Payload(s)
+		if err != nil {
+			return CallbackData{}, "", err
+		}
+		return data, BotPayloadBase64, nil
 	}
-	return CallbackData{}, ErrInvalidPayloadType
+	return CallbackData{}, "", ErrInvalidPayloadType
 }
 
 //	func (bot *Bot[T]) encodePayload(d CallbackData) (string, error) {
 //		return encodePayload(bot.payloadType, d)
 //	}
 func (bot *Bot[T]) decodePayload(s string) (CallbackData, error) {
-	return decodePayload(bot.payloadType, s)
+	data, decodedType, err := decodePayload(bot.payloadType, s, bot.strictPayloadType)
+	if err != nil {
+		return CallbackData{}, err
+	}
+	if decodedType == BotPayloadBase64 && bot.debug && bot.logger != nil {
+		bot.logger.Debugf("decoded callback payload base64->json: raw=%q json=%s", s, data.ToJson())
+	}
+	return data, nil
 }

handler_test.go

@@ -1,6 +1,7 @@
 package laniakea
 
 import (
+	"context"
 	"testing"
 
 	"git.nix13.pw/scuroneko/laniakea/tgapi"
@@ -35,7 +36,7 @@ func TestBotMiddlewareReceivesLogger(t *testing.T) {
 		},
 	}
 
-	bot.handle(&tgapi.Update{
+	bot.handle(context.Background(), &tgapi.Update{
 		UpdateID: 1,
 		Type:     tgapi.UpdateTypePoll,
 		Poll: &tgapi.Poll{
@@ -51,7 +52,7 @@ func TestBotMiddlewareReceivesLogger(t *testing.T) {
 
 func TestAddUpdateHandlerRejectsReservedUpdateTypes(t *testing.T) {
 	plugin := NewPlugin[NoDB]("test")
-	handler := func(ctx *MsgContext, db NoDB) {}
+	handler := func(ctx *MsgContext, db NoDB) error { return nil }
 
 	for _, updateType := range []tgapi.UpdateType{
 		tgapi.UpdateTypeMessage,
@@ -110,7 +111,7 @@ func TestHandleUpdateHandlersPopulateFromContext(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			called := false
-			plugin := NewPlugin[NoDB]("test").AddUpdateHandler(tt.update.Type, func(ctx *MsgContext, db NoDB) {
+			plugin := NewPlugin[NoDB]("test").AddUpdateHandler(tt.update.Type, func(ctx *MsgContext, db NoDB) error {
 				called = true
 				if ctx.Update.UpdateID != tt.update.UpdateID {
 					t.Fatalf("unexpected update in context: got %d want %d", ctx.Update.UpdateID, tt.update.UpdateID)
@@ -127,6 +128,7 @@ func TestHandleUpdateHandlersPopulateFromContext(t *testing.T) {
 				if ctx.Msg != nil {
 					t.Fatalf("did not expect message context for %s", tt.name)
 				}
+				return nil
 			})
 
 			bot := &Bot[NoDB]{
@@ -134,7 +136,7 @@ func TestHandleUpdateHandlersPopulateFromContext(t *testing.T) {
 				plugins: []Plugin[NoDB]{clonePlugin(plugin)},
 			}
 
-			bot.handle(tt.update)
+			bot.handle(context.Background(), tt.update)
 
 			if !called {
 				t.Fatalf("expected update handler for %s to be called", tt.name)
@@ -147,7 +149,7 @@ func TestHandleUpdateHandlersReceiveIsolatedContexts(t *testing.T) {
 	firstCalled := false
 	secondCalled := false
 
-	first := NewPlugin[NoDB]("first").AddUpdateHandler(tgapi.UpdateTypeInlineQuery, func(ctx *MsgContext, db NoDB) {
+	first := NewPlugin[NoDB]("first").AddUpdateHandler(tgapi.UpdateTypeInlineQuery, func(ctx *MsgContext, db NoDB) error {
 		firstCalled = true
 		if ctx.FromID != 41 {
 			t.Fatalf("unexpected FromID in first handler: got %d want 41", ctx.FromID)
@@ -156,8 +158,9 @@ func TestHandleUpdateHandlersReceiveIsolatedContexts(t *testing.T) {
 		ctx.FromID = 999
 		ctx.Text = "mutated"
 		ctx.Args = []string{"mutated"}
+		return nil
 	})
-	second := NewPlugin[NoDB]("second").AddUpdateHandler(tgapi.UpdateTypeInlineQuery, func(ctx *MsgContext, db NoDB) {
+	second := NewPlugin[NoDB]("second").AddUpdateHandler(tgapi.UpdateTypeInlineQuery, func(ctx *MsgContext, db NoDB) error {
 		secondCalled = true
 		if ctx.From == nil {
 			t.Fatal("expected ctx.From to remain populated for second handler")
@@ -171,6 +174,7 @@ func TestHandleUpdateHandlersReceiveIsolatedContexts(t *testing.T) {
 		if len(ctx.Args) != 0 {
 			t.Fatalf("unexpected leaked Args in second handler: %v", ctx.Args)
 		}
+		return nil
 	})
 
 	bot := &Bot[NoDB]{
@@ -181,7 +185,7 @@ func TestHandleUpdateHandlersReceiveIsolatedContexts(t *testing.T) {
 		},
 	}
 
-	bot.handle(&tgapi.Update{
+	bot.handle(context.Background(), &tgapi.Update{
 		UpdateID: 3,
 		Type:     tgapi.UpdateTypeInlineQuery,
 		InlineQuery: &tgapi.InlineQuery{
@@ -199,7 +203,7 @@ func TestHandleUpdateHandlersReceiveIsolatedContexts(t *testing.T) {
 func TestHandleChannelPostCommandWithSenderChat(t *testing.T) {
 	called := false
 	plugin := NewPlugin[NoDB]("test")
-	plugin.NewCommand(func(ctx *MsgContext, db NoDB) {
+	plugin.NewCommand(func(ctx *MsgContext, db NoDB) error {
 		called = true
 		if ctx.Msg == nil {
 			t.Fatal("expected message context")
@@ -213,6 +217,7 @@ func TestHandleChannelPostCommandWithSenderChat(t *testing.T) {
 		if ctx.FromID != 0 {
 			t.Fatalf("expected zero FromID for sender_chat updates, got %d", ctx.FromID)
 		}
+		return nil
 	}, "ping")
 
 	bot := &Bot[NoDB]{
@@ -221,7 +226,7 @@ func TestHandleChannelPostCommandWithSenderChat(t *testing.T) {
 		plugins:  []Plugin[NoDB]{clonePlugin(plugin)},
 	}
 
-	bot.handle(&tgapi.Update{
+	bot.handle(context.Background(), &tgapi.Update{
 		UpdateID: 10,
 		Type:     tgapi.UpdateTypeChannelPost,
 		ChannelPost: &tgapi.Message{
@@ -236,3 +241,85 @@ func TestHandleChannelPostCommandWithSenderChat(t *testing.T) {
 		t.Fatal("expected channel post command handler to be called")
 	}
 }
+
+func TestCommandHandlerBindArgsEndToEnd(t *testing.T) {
+	type banInput struct {
+		UserID int
+		Reason string
+	}
+
+	var got banInput
+	plugin := NewPlugin[NoDB]("test")
+	plugin.NewCommand(func(ctx *MsgContext, db NoDB) error {
+		return ctx.BindArgs(&got)
+	}, "ban",
+		NewCommandArg("user_id").SetValueType(CommandValueIntType).SetRequired(),
+		NewCommandArg("reason").SetRequired(),
+	)
+
+	bot := &Bot[NoDB]{
+		logger:   slog.CreateLogger(),
+		prefixes: []string{"/"},
+		plugins:  []Plugin[NoDB]{clonePlugin(plugin)},
+	}
+
+	bot.handle(context.Background(), &tgapi.Update{
+		UpdateID: 11,
+		Type:     tgapi.UpdateTypeMessage,
+		Message: &tgapi.Message{
+			MessageID: 1,
+			Text:      "/ban 42 too loud",
+			Chat:      &tgapi.Chat{ID: 99, Type: string(tgapi.ChatTypePrivate)},
+		},
+	})
+
+	want := banInput{UserID: 42, Reason: "too loud"}
+	if got != want {
+		t.Fatalf("unexpected bound input: got %#v want %#v", got, want)
+	}
+}
+
+func TestPayloadHandlerBindArgsEndToEnd(t *testing.T) {
+	type payloadInput struct {
+		ID   int
+		Note string
+	}
+
+	var got payloadInput
+	plugin := NewPlugin[NoDB]("test")
+	plugin.NewPayload(func(ctx *MsgContext, db NoDB) error {
+		return ctx.BindArgs(&got)
+	}, "approve",
+		NewCommandArg("id").SetValueType(CommandValueIntType).SetRequired(),
+		NewCommandArg("note").SetRequired(),
+	)
+
+	bot := &Bot[NoDB]{
+		logger:      slog.CreateLogger(),
+		payloadType: BotPayloadJson,
+		plugins:     []Plugin[NoDB]{clonePlugin(plugin)},
+	}
+
+	data, err := encodeJsonPayload(CallbackData{
+		Command: "approve",
+		Args:    []string{"7", "looks", "good"},
+	})
+	if err != nil {
+		t.Fatalf("encodeJsonPayload returned error: %v", err)
+	}
+
+	bot.handle(context.Background(), &tgapi.Update{
+		UpdateID: 12,
+		Type:     tgapi.UpdateTypeCallbackQuery,
+		CallbackQuery: &tgapi.CallbackQuery{
+			ID:   "cb-1",
+			Data: data,
+			From: tgapi.User{ID: 1},
+		},
+	})
+
+	want := payloadInput{ID: 7, Note: "looks good"}
+	if got != want {
+		t.Fatalf("unexpected bound payload input: got %#v want %#v", got, want)
+	}
+}

keyboard.go

@@ -136,14 +136,22 @@ func NewInlineKeyboard(payloadType BotPayloadType, maxRow int) *InlineKeyboard {
 	}
 }
 
-// SetPayloadType sets the serialization format for callback data added via
+// SetPayloadType sets the keyboard-local serialization format for callback data added via
 // AddCallbackButton and AddCallbackButtonStyle methods.
-// It should be one of BotPayloadJson or BotPayloadBase64.
+// It overrides the bot's default payload type for this keyboard only.
 func (in *InlineKeyboard) SetPayloadType(t BotPayloadType) *InlineKeyboard {
 	in.payloadType = t
 	return in
 }
 
+// GetPayloadType returns the keyboard-local callback payload encoding type.
+func (in *InlineKeyboard) GetPayloadType() BotPayloadType { return in.payloadType }
+
+func (in *InlineKeyboard) SetMaxRow(maxRow int) *InlineKeyboard {
+	in.maxRow = maxRow
+	return in
+}
+
 // Internal helper that appends a button and auto-flushes a full row.
 func (in *InlineKeyboard) append(button tgapi.InlineKeyboardButton) *InlineKeyboard {
 	if in.CurrentLine.Len() == in.maxRow {

keyboard_test.go

@@ -1,6 +1,8 @@
 package laniakea
 
 import (
+	"errors"
+	"reflect"
 	"strings"
 	"testing"
 )
@@ -42,3 +44,54 @@ func TestInlineKeyboardBuilderPreservesConfiguredButtonFields(t *testing.T) {
 		t.Fatalf("unexpected url: %q", button.URL)
 	}
 }
+
+func TestInlineKeyboardGetPayloadTypeReturnsLocalOverride(t *testing.T) {
+	kb := NewInlineKeyboardJson(2)
+	if got := kb.GetPayloadType(); got != BotPayloadJson {
+		t.Fatalf("unexpected initial payload type: %q", got)
+	}
+	kb.SetPayloadType(BotPayloadBase64)
+	if got := kb.GetPayloadType(); got != BotPayloadBase64 {
+		t.Fatalf("unexpected updated payload type: %q", got)
+	}
+}
+
+func TestDecodePayloadAcceptsBase64KeyboardPayloadWhenBotPrefersJSON(t *testing.T) {
+	kb := NewInlineKeyboardBase64(1).
+		AddCallbackButton("A", "cmd", 1, "two")
+
+	got, _, err := decodePayload(BotPayloadJson, kb.Get().InlineKeyboard[0][0].CallbackData, false)
+	if err != nil {
+		t.Fatalf("decodePayload returned error: %v", err)
+	}
+
+	want := CallbackData{Command: "cmd", Args: []string{"1", "two"}}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("unexpected payload: got %#v want %#v", got, want)
+	}
+}
+
+func TestDecodePayloadAcceptsJSONKeyboardPayloadWhenBotPrefersBase64(t *testing.T) {
+	kb := NewInlineKeyboardJson(1).
+		AddCallbackButton("A", "cmd", 1, "two")
+
+	got, _, err := decodePayload(BotPayloadBase64, kb.Get().InlineKeyboard[0][0].CallbackData, false)
+	if err != nil {
+		t.Fatalf("decodePayload returned error: %v", err)
+	}
+
+	want := CallbackData{Command: "cmd", Args: []string{"1", "two"}}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("unexpected payload: got %#v want %#v", got, want)
+	}
+}
+
+func TestDecodePayloadStrictRejectsMismatchedType(t *testing.T) {
+	kb := NewInlineKeyboardBase64(1).
+		AddCallbackButton("A", "cmd", 1)
+
+	_, _, err := decodePayload(BotPayloadJson, kb.Get().InlineKeyboard[0][0].CallbackData, true)
+	if !errors.Is(err, ErrPayloadTypeMismatch) {
+		t.Fatalf("expected ErrPayloadTypeMismatch, got %v", err)
+	}
+}

msg_context.go

@@ -2,7 +2,11 @@ package laniakea
 
 import (
 	"context"
+	"errors"
 	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
 	"time"
 
 	"git.nix13.pw/scuroneko/laniakea/tgapi"
@@ -35,6 +39,9 @@ type MsgContext struct {
 	l10n          *L10n
 	draftProvider *DraftProvider
 	payloadType   BotPayloadType
+	sceneRuntime  sceneRuntime
+
+	ctx context.Context
 }
 
 // AnswerMessage represents a message sent or edited via MsgContext.
@@ -48,6 +55,10 @@ type AnswerMessage struct {
 
 // Internal helper for text edits with optional keyboard and parse mode.
 func (ctx *MsgContext) edit(messageId int, text string, keyboard *InlineKeyboard, parseMode tgapi.ParseMode) *AnswerMessage {
+	if err := validateMessageText(text); err != nil {
+		ctx.Logger.Errorln(err)
+		return nil
+	}
 	params := tgapi.EditMessageTextP{
 		Text:      text,
 		ParseMode: parseMode,
@@ -59,13 +70,13 @@ func (ctx *MsgContext) edit(messageId int, text string, keyboard *InlineKeyboard
 	case ctx.InlineMsgId != "":
 		params.InlineMessageID = ctx.InlineMsgId
 	default:
-		ctx.Logger.Errorln("Can't edit message: no valid message target")
+		ctx.Logger.Errorln(ErrEditTargetMissing)
 		return nil
 	}
 	if keyboard != nil {
 		params.ReplyMarkup = keyboard.Get()
 	}
-	msg, _, err := ctx.Api.EditMessageText(params)
+	msg, _, err := ctx.Api.EditMessageTextWithContext(ctx.Context(), params)
 	if err != nil {
 		ctx.Logger.Errorln(err)
 		return nil
@@ -96,7 +107,7 @@ func (m *AnswerMessage) EditMarkdown(text string) *AnswerMessage {
 // Internal helper for editing callback-linked messages.
 func (ctx *MsgContext) editCallback(text string, keyboard *InlineKeyboard, parseMode tgapi.ParseMode) *AnswerMessage {
 	if ctx.CallbackMsgId == 0 && ctx.InlineMsgId == "" {
-		ctx.Logger.Errorln("Can't edit non-callback update message")
+		ctx.Logger.Errorln(ErrCallbackMessageMissing)
 		return nil
 	}
 	return ctx.edit(ctx.CallbackMsgId, text, keyboard, parseMode)
@@ -128,6 +139,10 @@ func (ctx *MsgContext) EditCallbackfMarkdown(format string, keyboard *InlineKeyb
 
 // Internal helper for media-caption edits.
 func (ctx *MsgContext) editPhotoText(messageId int, text string, kb *InlineKeyboard, parseMode tgapi.ParseMode) *AnswerMessage {
+	if err := validateCaptionText(text); err != nil {
+		ctx.Logger.Errorln(err)
+		return nil
+	}
 	params := tgapi.EditMessageCaptionP{
 		Caption:   text,
 		ParseMode: parseMode,
@@ -139,14 +154,14 @@ func (ctx *MsgContext) editPhotoText(messageId int, text string, kb *InlineKeybo
 	case ctx.InlineMsgId != "":
 		params.InlineMessageID = ctx.InlineMsgId
 	default:
-		ctx.Logger.Errorln("Can't edit caption: no valid message target")
+		ctx.Logger.Errorln(ErrEditTargetMissing)
 		return nil
 	}
 	if kb != nil {
 		params.ReplyMarkup = kb.Get()
 	}
 
-	msg, _, err := ctx.Api.EditMessageCaption(params)
+	msg, _, err := ctx.Api.EditMessageCaptionWithContext(ctx.Context(), params)
 	if err != nil {
 		ctx.Logger.Errorln(err)
 		return nil
@@ -187,7 +202,11 @@ func (m *AnswerMessage) EditCaptionKeyboardMarkdown(text string, kb *InlineKeybo
 // Internal helper for message replies with optional keyboard and parse mode.
 func (ctx *MsgContext) answer(text string, keyboard *InlineKeyboard, parseMode tgapi.ParseMode) *AnswerMessage {
 	if ctx.Msg == nil {
-		ctx.Logger.Errorln("Can't answer message without a message")
+		ctx.Logger.Errorln(ErrMessageContextNil)
+		return nil
+	}
+	if err := validateMessageText(text); err != nil {
+		ctx.Logger.Errorln(err)
 		return nil
 	}
 	params := tgapi.SendMessageP{
@@ -205,7 +224,7 @@ func (ctx *MsgContext) answer(text string, keyboard *InlineKeyboard, parseMode t
 		params.DirectMessagesTopicID = ctx.Msg.DirectMessageTopic.TopicID
 	}
 
-	msg, err := ctx.Api.SendMessage(params)
+	msg, err := ctx.Api.SendMessageWithContext(ctx.Context(), params)
 	if err != nil {
 		ctx.Logger.Errorln(err)
 		return nil
@@ -220,6 +239,14 @@ func (ctx *MsgContext) Answer(text string) *AnswerMessage {
 	return ctx.answer(text, nil, tgapi.ParseNone)
 }
 
+// AnswerLong sends one or more plain-text messages if text exceeds Telegram's limit.
+//
+// The text is split into Telegram-safe chunks. Returned messages preserve send
+// order. If a chunk fails to send, already-sent messages are returned.
+func (ctx *MsgContext) AnswerLong(text string) []*AnswerMessage {
+	return ctx.answerLong(text, nil, tgapi.ParseNone)
+}
+
 // AnswerMarkdown sends a message using MarkdownV2 formatting.
 //
 // ⚠️ WARNING: User input must be escaped with laniakea.EscapeMarkdownV2() before passing here.
@@ -232,6 +259,11 @@ func (ctx *MsgContext) Answerf(template string, args ...any) *AnswerMessage {
 	return ctx.answer(fmt.Sprintf(template, args...), nil, tgapi.ParseNone)
 }
 
+// AnswerLongf formats a string using fmt.Sprintf and sends it as one or more plain-text messages.
+func (ctx *MsgContext) AnswerLongf(template string, args ...any) []*AnswerMessage {
+	return ctx.answerLong(fmt.Sprintf(template, args...), nil, tgapi.ParseNone)
+}
+
 // AnswerfMarkdown formats a string using fmt.Sprintf and sends it using MarkdownV2.
 //
 // ⚠️ WARNING: User input must be escaped with laniakea.EscapeMarkdownV2() before passing here.
@@ -244,6 +276,13 @@ func (ctx *MsgContext) Keyboard(text string, kb *InlineKeyboard) *AnswerMessage
 	return ctx.answer(text, kb, tgapi.ParseNone)
 }
 
+// KeyboardLong sends long plain text split across multiple messages.
+//
+// The inline keyboard is attached only to the final chunk.
+func (ctx *MsgContext) KeyboardLong(text string, kb *InlineKeyboard) []*AnswerMessage {
+	return ctx.answerLong(text, kb, tgapi.ParseNone)
+}
+
 // KeyboardMarkdown sends a message with an inline keyboard using MarkdownV2.
 //
 // ⚠️ WARNING: User input must be escaped with laniakea.EscapeMarkdownV2() before passing here.
@@ -251,10 +290,53 @@ func (ctx *MsgContext) KeyboardMarkdown(text string, keyboard *InlineKeyboard) *
 	return ctx.answer(text, keyboard, tgapi.ParseMDV2)
 }
 
+func (ctx *MsgContext) answerLong(text string, keyboard *InlineKeyboard, parseMode tgapi.ParseMode) []*AnswerMessage {
+	if parseMode != tgapi.ParseNone {
+		ctx.Logger.Errorln(ErrMessageSplitImpossible)
+		return nil
+	}
+	if ctx.Msg == nil {
+		ctx.Logger.Errorln(ErrMessageContextNil)
+		return nil
+	}
+	if err := validateMessageText(text); err == nil {
+		msg := ctx.answer(text, keyboard, parseMode)
+		if msg == nil {
+			return nil
+		}
+		return []*AnswerMessage{msg}
+	} else if !errors.Is(err, ErrMessageTooLong) {
+		ctx.Logger.Errorln(err)
+		return nil
+	}
+
+	parts := SplitMessageText(text)
+	messages := make([]*AnswerMessage, 0, len(parts))
+	for i, part := range parts {
+		partKeyboard := (*InlineKeyboard)(nil)
+		if i == len(parts)-1 {
+			partKeyboard = keyboard
+		}
+		msg := ctx.answer(part, partKeyboard, parseMode)
+		if msg == nil {
+			break
+		}
+		messages = append(messages, msg)
+	}
+	if len(messages) == 0 {
+		return nil
+	}
+	return messages
+}
+
 // Internal helper for photo replies with optional caption and keyboard.
 func (ctx *MsgContext) answerPhoto(photoId, text string, kb *InlineKeyboard, parseMode tgapi.ParseMode) *AnswerMessage {
 	if ctx.Msg == nil {
-		ctx.Logger.Errorln("Can't answer message without a message")
+		ctx.Logger.Errorln(ErrMessageContextNil)
+		return nil
+	}
+	if err := validateCaptionText(text); err != nil {
+		ctx.Logger.Errorln(err)
 		return nil
 	}
 	params := tgapi.SendPhotoP{
@@ -273,7 +355,7 @@ func (ctx *MsgContext) answerPhoto(photoId, text string, kb *InlineKeyboard, par
 		params.DirectMessagesTopicID = int(ctx.Msg.DirectMessageTopic.TopicID)
 	}
 
-	msg, err := ctx.Api.SendPhoto(params)
+	msg, err := ctx.Api.SendPhotoWithContext(ctx.Context(), params)
 	if err != nil {
 		ctx.Logger.Errorln(err)
 		return nil
@@ -322,14 +404,14 @@ func (ctx *MsgContext) AnswerPhotofMarkdown(photoId, template string, args ...an
 // Internal helper that deletes a message by ID.
 func (ctx *MsgContext) delete(messageId int) {
 	if messageId == 0 {
-		ctx.Logger.Errorln("Can't delete message: message ID zero")
+		ctx.Logger.Errorln(ErrMessageIDZero)
 		return
 	}
 	if ctx.Msg == nil {
-		ctx.Logger.Errorln("Can't delete message: no chat message context")
+		ctx.Logger.Errorln(ErrMessageContextNil)
 		return
 	}
-	_, err := ctx.Api.DeleteMessage(tgapi.DeleteMessageP{
+	_, err := ctx.Api.DeleteMessageWithContext(ctx.Context(), tgapi.DeleteMessageP{
 		ChatID:    ctx.Msg.Chat.ID,
 		MessageID: messageId,
 	})
@@ -344,7 +426,7 @@ func (m *AnswerMessage) Delete() { m.ctx.delete(m.MessageID) }
 // CallbackDelete deletes the message that triggered the callback query.
 func (ctx *MsgContext) CallbackDelete() {
 	if ctx.CallbackMsgId == 0 {
-		ctx.Logger.Errorln("Can't delete callback message: no callback message ID")
+		ctx.Logger.Errorln(ErrCallbackMessageMissing)
 		return
 	}
 	ctx.delete(ctx.CallbackMsgId)
@@ -355,7 +437,7 @@ func (ctx *MsgContext) answerCallbackQuery(url, text string, showAlert bool) {
 	if len(ctx.CallbackQueryId) == 0 {
 		return
 	}
-	_, err := ctx.Api.AnswerCallbackQuery(tgapi.AnswerCallbackQueryP{
+	_, err := ctx.Api.AnswerCallbackQueryWithContext(ctx.Context(), tgapi.AnswerCallbackQueryP{
 		CallbackQueryID: ctx.CallbackQueryId,
 		Text:            text, ShowAlert: showAlert, URL: url,
 	})
@@ -388,7 +470,7 @@ func (ctx *MsgContext) SendAction(action tgapi.ChatActionType) {
 	if ctx.Msg.MessageThreadID > 0 {
 		params.MessageThreadID = ctx.Msg.MessageThreadID
 	}
-	_, err := ctx.Api.SendChatAction(params)
+	_, err := ctx.Api.SendChatActionWithContext(ctx.Context(), params)
 	if err != nil {
 		ctx.Logger.Errorln(err)
 	}
@@ -411,20 +493,20 @@ func (ctx *MsgContext) Error(err error) { ctx.error(err) }
 
 func (ctx *MsgContext) newDraft(parseMode tgapi.ParseMode) *Draft {
 	if ctx.Msg == nil {
-		ctx.Logger.Errorln("can't create draft: ctx.Msg is nil")
+		ctx.Logger.Errorln(ErrMessageContextNil)
 		return nil
 	}
 	if ctx.Api == nil {
-		ctx.Logger.Errorln("can't create draft: ctx.Api is nil")
+		ctx.Logger.Errorln(ErrAPIIsNil)
 		return nil
 	}
 	if ctx.draftProvider == nil {
-		ctx.Logger.Errorln("can't create draft: ctx.draftProvider is nil")
+		ctx.Logger.Errorln(ErrDraftProviderNil)
 		return nil
 	}
 
 	if ctx.Api.Limiter != nil {
-		c, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		c, cancel := context.WithTimeout(ctx.Context(), 5*time.Second)
 		defer cancel()
 		if err := ctx.Api.Limiter.Wait(c, ctx.Msg.Chat.ID); err != nil {
 			ctx.Logger.Errorln(err)
@@ -464,3 +546,161 @@ func (ctx *MsgContext) Translate(key string) string {
 func (ctx *MsgContext) NewInlineKeyboard(maxRow int) *InlineKeyboard {
 	return NewInlineKeyboard(ctx.payloadType, maxRow)
 }
+
+func bindPositional(args []string, dst any) error {
+	v := reflect.ValueOf(dst)
+	if v.Kind() != reflect.Pointer || v.IsNil() {
+		return ErrBindArgsTargetNotPointer
+	}
+
+	v = v.Elem()
+	if v.Kind() != reflect.Struct {
+		return ErrBindArgsTargetNotStruct
+	}
+
+	t := v.Type()
+	fields := make([]int, 0, v.NumField())
+
+	for i := 0; i < v.NumField(); i++ {
+		field := v.Field(i)
+		if !field.CanSet() {
+			continue
+		}
+		fields = append(fields, i)
+	}
+
+	argIndex := 0
+	for fieldPos, fieldIndex := range fields {
+		field := v.Field(fieldIndex)
+		fieldType := t.Field(fieldIndex)
+
+		if argIndex >= len(args) {
+			// Leave trailing fields at their zero values when arguments run out.
+			break
+		}
+
+		isLastBindableField := fieldPos == len(fields)-1
+
+		raw := args[argIndex]
+		if isLastBindableField && field.Kind() == reflect.String {
+			raw = strings.Join(args[argIndex:], " ")
+		}
+
+		switch field.Kind() {
+		case reflect.String:
+			field.SetString(raw)
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			n, err := strconv.ParseInt(raw, 10, 64)
+			if err != nil {
+				return fmt.Errorf("%w: field %s: %v", ErrBindArgsConversion, fieldType.Name, err)
+			}
+			field.SetInt(n)
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			n, err := strconv.ParseUint(raw, 10, 64)
+			if err != nil {
+				return fmt.Errorf("%w: field %s: %v", ErrBindArgsConversion, fieldType.Name, err)
+			}
+			field.SetUint(n)
+		case reflect.Float32, reflect.Float64:
+			f, err := strconv.ParseFloat(raw, 64)
+			if err != nil {
+				return fmt.Errorf("%w: field %s: %v", ErrBindArgsConversion, fieldType.Name, err)
+			}
+			field.SetFloat(f)
+		case reflect.Bool:
+			b, err := strconv.ParseBool(raw)
+			if err != nil {
+				return fmt.Errorf("%w: field %s: %v", ErrBindArgsConversion, fieldType.Name, err)
+			}
+			field.SetBool(b)
+		default:
+			return fmt.Errorf("%w: field %s: %s", ErrBindArgsUnsupportedFieldType, fieldType.Name, field.Kind())
+		}
+
+		if isLastBindableField && field.Kind() == reflect.String {
+			break
+		}
+		argIndex++
+	}
+
+	return nil
+}
+
+// BindArgs binds positional command arguments from ctx.Args into dst.
+//
+// Exported struct fields are filled in declaration order. When fewer arguments
+// are provided than fields, the remaining fields keep their zero values. If the
+// final bindable field is a string, it receives the remaining arguments joined
+// with spaces.
+func (ctx *MsgContext) BindArgs(dst any) error {
+	return bindPositional(ctx.Args, dst)
+}
+
+// Context returns the request-scoped context associated with the current update.
+func (ctx *MsgContext) Context() context.Context {
+	if ctx.ctx == nil {
+		return context.Background()
+	}
+	return ctx.ctx
+}
+
+func (ctx *MsgContext) EnterScene(name string) error {
+	scene, ok := ctx.sceneRuntime.FindScene(name)
+	if !ok {
+		return ErrSceneNotFound
+	}
+
+	key, ok := ctx.sceneRuntime.BuildSceneKey(scene.Scope, ctx)
+	if !ok {
+		return ErrCantFindSession
+	}
+
+	session := SceneSession{
+		Scene: scene.Name,
+		Step:  scene.Entry,
+	}
+
+	return ctx.sceneRuntime.SetSession(key, session)
+}
+func (ctx *MsgContext) EnterSceneStep(name, step string) error {
+	scene, ok := ctx.sceneRuntime.FindScene(name)
+	if !ok {
+		return ErrSceneNotFound
+	}
+	if _, ok := scene.Steps[step]; !ok {
+		return ErrSceneStepNotFound
+	}
+
+	key, ok := ctx.sceneRuntime.BuildSceneKey(scene.Scope, ctx)
+	if !ok {
+		return ErrCantFindSession
+	}
+
+	session := SceneSession{
+		Scene: scene.Name,
+		Step:  step,
+	}
+
+	return ctx.sceneRuntime.SetSession(key, session)
+}
+func (ctx *MsgContext) ExitScene() error {
+	_, session, err := ctx.sceneRuntime.FindSceneSession(ctx)
+	if err != nil {
+		return err
+	}
+	if session.Scene == "" {
+		return ErrNotInScene
+	}
+
+	scene, ok := ctx.sceneRuntime.FindScene(session.Scene)
+	if !ok {
+		return ErrSceneNotFound
+	}
+
+	key, ok := ctx.sceneRuntime.BuildSceneKey(scene.Scope, ctx)
+	if !ok {
+		return ErrCantFindSession
+	}
+
+	return ctx.sceneRuntime.DeleteSession(key)
+}

msg_context_test.go

@@ -2,8 +2,10 @@ package laniakea
 
 import (
 	"encoding/json"
+	"errors"
 	"io"
 	"net/http"
+	"reflect"
 	"strings"
 	"testing"
 
@@ -62,3 +64,247 @@ func TestAnswerPhotoIncludesDirectMessagesTopicID(t *testing.T) {
 		t.Fatalf("unexpected direct_messages_topic_id: %v", got)
 	}
 }
+
+func TestBindArgsBindsScalarFields(t *testing.T) {
+	type input struct {
+		ID     int
+		Active bool
+		Score  float64
+		Name   string
+	}
+
+	ctx := &MsgContext{Args: []string{"42", "true", "3.5", "Ada", "Lovelace"}}
+	var got input
+
+	if err := ctx.BindArgs(&got); err != nil {
+		t.Fatalf("BindArgs returned error: %v", err)
+	}
+
+	want := input{
+		ID:     42,
+		Active: true,
+		Score:  3.5,
+		Name:   "Ada Lovelace",
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("unexpected bound value: got %#v want %#v", got, want)
+	}
+}
+
+func TestBindArgsLeavesTrailingFieldsZeroWhenArgsRunOut(t *testing.T) {
+	type input struct {
+		ID     int
+		Reason string
+		Admin  bool
+	}
+
+	ctx := &MsgContext{Args: []string{"7"}}
+	var got input
+
+	if err := ctx.BindArgs(&got); err != nil {
+		t.Fatalf("BindArgs returned error: %v", err)
+	}
+
+	if got.ID != 7 {
+		t.Fatalf("unexpected ID: got %d want 7", got.ID)
+	}
+	if got.Reason != "" {
+		t.Fatalf("expected zero-value Reason, got %q", got.Reason)
+	}
+	if got.Admin {
+		t.Fatal("expected zero-value Admin")
+	}
+}
+
+func TestBindArgsRejectsInvalidTargets(t *testing.T) {
+	ctx := &MsgContext{Args: []string{"1"}}
+
+	if err := ctx.BindArgs(nil); !errors.Is(err, ErrBindArgsTargetNotPointer) {
+		t.Fatalf("expected ErrBindArgsTargetNotPointer for nil target, got %v", err)
+	}
+
+	var notStruct int
+	if err := ctx.BindArgs(&notStruct); !errors.Is(err, ErrBindArgsTargetNotStruct) {
+		t.Fatalf("expected ErrBindArgsTargetNotStruct for non-struct target, got %v", err)
+	}
+}
+
+func TestBindArgsReportsConversionFailures(t *testing.T) {
+	type input struct {
+		ID int
+	}
+
+	ctx := &MsgContext{Args: []string{"oops"}}
+	var got input
+
+	err := ctx.BindArgs(&got)
+	if err == nil {
+		t.Fatal("expected BindArgs to fail")
+	}
+	if !errors.Is(err, ErrBindArgsConversion) {
+		t.Fatalf("expected ErrBindArgsConversion, got %v", err)
+	}
+	if !strings.Contains(err.Error(), "field ID") {
+		t.Fatalf("expected field name in error, got %v", err)
+	}
+}
+
+func TestBindArgsRejectsUnsupportedFieldTypes(t *testing.T) {
+	type input struct {
+		Tags []string
+	}
+
+	ctx := &MsgContext{Args: []string{"tag"}}
+	var got input
+
+	err := ctx.BindArgs(&got)
+	if err == nil {
+		t.Fatal("expected BindArgs to fail")
+	}
+	if !errors.Is(err, ErrBindArgsUnsupportedFieldType) {
+		t.Fatalf("expected ErrBindArgsUnsupportedFieldType, got %v", err)
+	}
+}
+
+func TestAnswerRejectsEmptyMessage(t *testing.T) {
+	ctx := &MsgContext{
+		Msg:    &tgapi.Message{Chat: &tgapi.Chat{ID: 42, Type: string(tgapi.ChatTypePrivate)}},
+		Logger: slog.CreateLogger(),
+	}
+
+	if answer := ctx.Answer(""); answer != nil {
+		t.Fatal("expected nil answer for empty message")
+	}
+}
+
+func TestAnswerRejectsLongMessageWithoutSendingRequest(t *testing.T) {
+	client := &http.Client{
+		Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+			t.Fatal("unexpected HTTP request")
+			return nil, nil
+		}),
+	}
+
+	api := tgapi.NewAPI(
+		tgapi.NewAPIOpts("token").
+			SetAPIUrl("https://example.test").
+			SetHTTPClient(client),
+	)
+	defer func() {
+		if err := api.Close(); err != nil {
+			t.Fatalf("Close returned error: %v", err)
+		}
+	}()
+
+	ctx := &MsgContext{
+		Api:    api,
+		Msg:    &tgapi.Message{Chat: &tgapi.Chat{ID: 42, Type: string(tgapi.ChatTypePrivate)}},
+		Logger: slog.CreateLogger(),
+	}
+
+	if answer := ctx.Answer(strings.Repeat("a", maxMessageTextLen+1)); answer != nil {
+		t.Fatal("expected nil answer for long message")
+	}
+}
+
+func TestValidateMessageText(t *testing.T) {
+	if err := validateMessageText(""); !errors.Is(err, ErrEmptyMessage) {
+		t.Fatalf("expected ErrEmptyMessage, got %v", err)
+	}
+	if err := validateMessageText(strings.Repeat("a", maxMessageTextLen+1)); !errors.Is(err, ErrMessageTooLong) {
+		t.Fatalf("expected ErrMessageTooLong, got %v", err)
+	}
+	if err := validateMessageText("ok"); err != nil {
+		t.Fatalf("expected nil error, got %v", err)
+	}
+}
+
+func TestValidateCaptionText(t *testing.T) {
+	if err := validateCaptionText(strings.Repeat("a", maxMessageCaptionLen+1)); !errors.Is(err, ErrCaptionTooLong) {
+		t.Fatalf("expected ErrCaptionTooLong, got %v", err)
+	}
+	if err := validateCaptionText(""); err != nil {
+		t.Fatalf("expected nil error, got %v", err)
+	}
+}
+
+func TestSplitMessageTextPreservesContent(t *testing.T) {
+	text := "alpha beta\n" + strings.Repeat("x", maxMessageTextLen) + " omega"
+
+	parts := SplitMessageText(text)
+	if len(parts) < 2 {
+		t.Fatalf("expected multiple parts, got %d", len(parts))
+	}
+
+	for i, part := range parts {
+		if got := len([]rune(part)); got > maxMessageTextLen {
+			t.Fatalf("part %d exceeded limit: %d", i, got)
+		}
+	}
+
+	if got := strings.Join(parts, ""); got != text {
+		t.Fatalf("split/join mismatch: got %q want %q", got, text)
+	}
+}
+
+func TestAnswerLongSplitsRequestsAndAttachesKeyboardToLastChunk(t *testing.T) {
+	var requests []map[string]any
+
+	client := &http.Client{
+		Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+			body, err := io.ReadAll(req.Body)
+			if err != nil {
+				t.Fatalf("failed to read request body: %v", err)
+			}
+			var got map[string]any
+			if err := json.Unmarshal(body, &got); err != nil {
+				t.Fatalf("failed to decode request body: %v", err)
+			}
+			requests = append(requests, got)
+			return &http.Response{
+				StatusCode: http.StatusOK,
+				Header:     http.Header{"Content-Type": []string{"application/json"}},
+				Body:       io.NopCloser(strings.NewReader(`{"ok":true,"result":{"message_id":9,"date":1}}`)),
+			}, nil
+		}),
+	}
+
+	api := tgapi.NewAPI(
+		tgapi.NewAPIOpts("token").
+			SetAPIUrl("https://example.test").
+			SetHTTPClient(client),
+	)
+	defer func() {
+		if err := api.Close(); err != nil {
+			t.Fatalf("Close returned error: %v", err)
+		}
+	}()
+
+	ctx := &MsgContext{
+		Api:    api,
+		Msg:    &tgapi.Message{Chat: &tgapi.Chat{ID: 42, Type: string(tgapi.ChatTypePrivate)}},
+		Logger: slog.CreateLogger(),
+	}
+	kb := NewInlineKeyboardJson(1).AddCallbackButton("A", "cmd")
+	text := strings.Repeat("a", maxMessageTextLen) + " " + strings.Repeat("b", 32)
+
+	messages := ctx.KeyboardLong(text, kb)
+	if got := len(messages); got != 2 {
+		t.Fatalf("expected 2 sent messages, got %d", got)
+	}
+	if got := len(requests); got != 2 {
+		t.Fatalf("expected 2 requests, got %d", got)
+	}
+	if _, ok := requests[0]["reply_markup"]; ok {
+		t.Fatal("did not expect keyboard on first chunk")
+	}
+	if _, ok := requests[1]["reply_markup"]; !ok {
+		t.Fatal("expected keyboard on final chunk")
+	}
+
+	gotTexts := []string{requests[0]["text"].(string), requests[1]["text"].(string)}
+	wantTexts := SplitMessageText(text)
+	if !reflect.DeepEqual(gotTexts, wantTexts) {
+		t.Fatalf("unexpected chunk texts: got %q want %q", gotTexts, wantTexts)
+	}
+}

plugins.go

@@ -81,7 +81,8 @@ func (c CommandArg) SetRequired() CommandArg {
 
 // CommandExecutor is the function type that executes a command.
 // It receives the message context and a database context (generic).
-type CommandExecutor[T DbContext] func(ctx *MsgContext, dbContext T)
+// Returning a non-nil error routes it through the bot's error handler.
+type CommandExecutor[T DbContext] func(ctx *MsgContext, dbContext T) error
 
 // Command represents a bot command with arguments, description, and executor.
 // Can be registered in a Plugin and optionally skipped from auto-generation.
@@ -160,6 +161,7 @@ type Plugin[T DbContext] struct {
 	name        string                       // Name of the plugin (e.g., "admin", "user")
 	commands    map[string]*Command[T]       // Registered commands (triggered by message)
 	payloads    map[string]*Command[T]       // Registered payloads (triggered by callback data)
+	scenes      map[string]*Scene[T]         // Optional scenes for multi-step interactions
 	middlewares extypes.Slice[Middleware[T]] // Shared middlewares for all commands/payloads
 	skipAutoCmd bool                         // If true, all commands in this plugin are excluded from auto-help
 	logger      *slog.Logger
@@ -176,6 +178,7 @@ func NewPlugin[T DbContext](name string) *Plugin[T] {
 		commands:    make(map[string]*Command[T]),
 		payloads:    make(map[string]*Command[T]),
 		middlewares: make(extypes.Slice[Middleware[T]], 0),
+		scenes:      make(map[string]*Scene[T]),
 		skipAutoCmd: false,
 		logger:      nil,
 		handlers:    make(map[tgapi.UpdateType]CommandExecutor[T]),
@@ -212,6 +215,18 @@ func (p *Plugin[T]) NewPayload(exec CommandExecutor[T], command string, args ...
 	return cmd
 }
 
+func (p *Plugin[T]) AddScene(scene *Scene[T]) *Plugin[T] {
+	scene.PluginName = p.name
+	scene.setPluginName(p.name)
+	return p
+}
+func (p *Plugin[T]) NewScene(name string) *Scene[T] {
+	scene := NewScene[T](name)
+	scene.setPluginName(p.name)
+	p.AddScene(scene)
+	return scene
+}
+
 // AddUpdateHandler registers a handler for a non-command update type.
 // Message, channel post, and callback query updates stay on the command/payload flow.
 func (p *Plugin[T]) AddUpdateHandler(t tgapi.UpdateType, handler CommandExecutor[T]) *Plugin[T] {
@@ -309,7 +324,9 @@ func (p *Plugin[T]) executeCmd(cmd string, ctx *MsgContext, db T) {
 	}
 
 	// Execute command
-	command.exec(ctx, db)
+	if err := command.exec(ctx, db); err != nil {
+		ctx.error(err)
+	}
 }
 
 // Internal helper that validates and executes a payload handler.
@@ -333,7 +350,9 @@ func (p *Plugin[T]) executePayload(payload string, ctx *MsgContext, db T) {
 	}
 
 	// Execute payload
-	command.exec(ctx, db)
+	if err := command.exec(ctx, db); err != nil {
+		ctx.error(err)
+	}
 }
 
 // Internal helper that runs plugin middlewares in order.

plugins_test.go

@@ -6,7 +6,7 @@ import (
 )
 
 func TestValidateArgsRequiresFullMatch(t *testing.T) {
-	intCmd := NewCommand[NoDB](func(ctx *MsgContext, db NoDB) {}, "int", NewCommandArg("n").SetValueType(CommandValueIntType).SetRequired())
+	intCmd := NewCommand[NoDB](func(ctx *MsgContext, db NoDB) error { return nil }, "int", NewCommandArg("n").SetValueType(CommandValueIntType).SetRequired())
 	if err := intCmd.validateArgs([]string{"123"}); err != nil {
 		t.Fatalf("expected valid integer argument, got %v", err)
 	}
@@ -14,7 +14,7 @@ func TestValidateArgsRequiresFullMatch(t *testing.T) {
 		t.Fatalf("expected ErrCmdArgRegexpMismatch for partial int match, got %v", err)
 	}
 
-	boolCmd := NewCommand[NoDB](func(ctx *MsgContext, db NoDB) {}, "bool", NewCommandArg("flag").SetValueType(CommandValueBoolType).SetRequired())
+	boolCmd := NewCommand[NoDB](func(ctx *MsgContext, db NoDB) error { return nil }, "bool", NewCommandArg("flag").SetValueType(CommandValueBoolType).SetRequired())
 	if err := boolCmd.validateArgs([]string{"false"}); err != nil {
 		t.Fatalf("expected valid bool argument, got %v", err)
 	}
@@ -25,7 +25,7 @@ func TestValidateArgsRequiresFullMatch(t *testing.T) {
 
 func TestValidateArgsEnforcesRequiredArgIndex(t *testing.T) {
 	cmd := NewCommand[NoDB](
-		func(ctx *MsgContext, db NoDB) {},
+		func(ctx *MsgContext, db NoDB) error { return nil },
 		"mixed",
 		NewCommandArg("optional"),
 		NewCommandArg("required").SetRequired(),

scene.go

@@ -0,0 +1,195 @@
+package laniakea
+
+import (
+	"encoding/json"
+	"sync"
+)
+
+type SceneHandler[T any] func(ctx *SceneContext, db T) (SceneResult, error)
+type Scene[T any] struct {
+	Name       string
+	Scope      SceneScope
+	Entry      string // starting step
+	PluginName string
+
+	steps    map[string]SceneHandler[T]
+	commands map[string]SceneHandler[T]
+	message  SceneHandler[T]
+}
+
+func NewScene[T any](name string) *Scene[T] {
+	return &Scene[T]{
+		Name:     name,
+		Scope:    SceneScopeUserChat,
+		Entry:    "",
+		steps:    make(map[string]SceneHandler[T]),
+		commands: make(map[string]SceneHandler[T]),
+		message:  nil,
+	}
+}
+func (s *Scene[T]) SetScope(scope SceneScope) *Scene[T] {
+	s.Scope = scope
+	return s
+}
+func (s *Scene[T]) SetEntry(step string) *Scene[T] {
+	s.Entry = step
+	return s
+}
+func (s *Scene[T]) setPluginName(name string) *Scene[T] {
+	s.PluginName = name
+	return s
+}
+
+func (s *Scene[T]) OnStep(step string, handler SceneHandler[T]) *Scene[T] {
+	s.steps[step] = handler
+	return s
+}
+func (s *Scene[T]) OnCommand(cmd string, handler SceneHandler[T]) *Scene[T] {
+	s.commands[cmd] = handler
+	return s
+}
+func (s *Scene[T]) OnMessage(handler SceneHandler[T]) *Scene[T] {
+	s.message = handler
+	return s
+}
+
+func (s *Scene[T]) executeCommand(cmd string, ctx *SceneContext, db T) (SceneResult, bool, error) {
+	handler, ok := s.commands[cmd]
+	if !ok {
+		return SceneResult{}, false, nil
+	}
+	result, err := handler(ctx, db)
+	return result, true, err
+}
+func (s *Scene[T]) executeStep(step string, ctx *SceneContext, db T) (SceneResult, bool, error) {
+	handler, ok := s.steps[step]
+	if !ok {
+		return SceneResult{}, false, nil
+	}
+	result, err := handler(ctx, db)
+	return result, true, err
+}
+func (s *Scene[T]) executeMessage(ctx *SceneContext, db T) (SceneResult, bool, error) {
+	if s.message == nil {
+		return SceneResult{}, false, nil
+	}
+	result, err := s.message(ctx, db)
+	return result, true, err
+}
+
+type SceneSession struct {
+	Scene string
+	Step  string
+	Data  []byte
+}
+
+// SetData sets the session data. It is thread-safe and can be used to store any arbitrary data as a byte slice.
+func (s *SceneSession) SetData(data []byte) {
+	s.Data = data
+}
+
+// GetData retrieves the session data. It is thread-safe and returns the data as a byte slice.
+func (s *SceneSession) GetData() []byte {
+	return s.Data
+}
+func (s *SceneSession) HasData() bool {
+	return len(s.Data) > 0
+}
+
+// ClearData clears the session data. It is thread-safe and sets the data to nil.
+func (s *SceneSession) ClearData() {
+	s.Data = nil
+}
+
+// BindData binds the session data to the provided struct.
+func (s *SceneSession) BindData(v any) error {
+	if len(s.Data) == 0 {
+		return nil // No data to bind, return nil error
+	}
+	return json.Unmarshal(s.Data, v)
+}
+
+// SaveData saves the provided struct as JSON in the session data.
+func (s *SceneSession) SaveData(v any) error {
+	data, err := json.Marshal(v)
+	if err != nil {
+		return err
+	}
+	s.Data = data
+	return nil
+}
+
+type SessionStore interface {
+	Get(key string) (SceneSession, error)
+	Set(key string, session SceneSession) error
+	Delete(key string) error
+}
+
+type MemorySessionStore struct {
+	store map[string]SceneSession
+	mu    sync.RWMutex
+}
+
+func NewMemorySessionStore() *MemorySessionStore {
+	return &MemorySessionStore{
+		store: make(map[string]SceneSession),
+	}
+}
+func (s *MemorySessionStore) Get(key string) (SceneSession, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	if session, ok := s.store[key]; ok {
+		return session, nil
+	}
+	return SceneSession{}, nil
+}
+func (s *MemorySessionStore) Set(key string, session SceneSession) error {
+	s.mu.Lock()
+	s.store[key] = session
+	s.mu.Unlock()
+	return nil
+}
+func (s *MemorySessionStore) Delete(key string) error {
+	s.mu.Lock()
+	delete(s.store, key)
+	s.mu.Unlock()
+	return nil
+}
+
+type SceneResult struct {
+	Action SceneAction
+	Next   string
+}
+
+type SceneAction int
+
+const (
+	SceneActionStay SceneAction = iota
+	SceneActionNext
+	SceneActionExit
+	SceneActionPass
+)
+
+type SceneScope int
+
+const (
+	SceneScopeUser SceneScope = iota
+	SceneScopeChat
+	SceneScopeUserChat
+)
+
+type sceneRuntime interface {
+	FindScene(name string) (*sceneMeta, bool)
+	GetSession(key string) (SceneSession, error)
+	SetSession(key string, session SceneSession) error
+	DeleteSession(key string) error
+	BuildSceneKey(scope SceneScope, ctx *MsgContext) (string, bool)
+	FindSceneSession(ctx *MsgContext) (string, SceneSession, error)
+}
+
+type sceneMeta struct {
+	Name  string
+	Scope SceneScope
+	Entry string
+	Steps map[string]struct{}
+}

scene_context.go

@@ -0,0 +1,23 @@
+package laniakea
+
+type SceneContext struct {
+	*MsgContext
+	sess SceneSession
+	key  string
+}
+
+func (ctx *SceneContext) Next(step string) SceneResult {
+	return SceneResult{
+		Action: SceneActionNext,
+		Next:   step,
+	}
+}
+func (ctx *SceneContext) Stay() SceneResult {
+	return SceneResult{Action: SceneActionStay}
+}
+func (ctx *SceneContext) Exit() SceneResult {
+	return SceneResult{Action: SceneActionExit}
+}
+func (ctx *SceneContext) Pass() SceneResult {
+	return SceneResult{Action: SceneActionPass}
+}

scene_handler.go

@@ -0,0 +1,130 @@
+package laniakea
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+)
+
+func (bot *Bot[T]) tryHandleScene(ctx *MsgContext) (bool, error) {
+	key, session, err := bot.FindSceneSession(ctx)
+	if err != nil {
+		if errors.Is(err, ErrCantFindSession) || errors.Is(err, ErrMessageNil) {
+			return false, nil
+		}
+		return false, err
+	}
+	if session.Scene == "" {
+		return false, nil
+	}
+
+	for _, plugin := range bot.plugins {
+		scene, ok := plugin.scenes[session.Scene]
+		if !ok {
+			continue
+		}
+		if scene.PluginName != "" && scene.PluginName != plugin.name {
+			continue
+		}
+		sceneCtx := &SceneContext{
+			MsgContext: ctx,
+			sess:       session,
+			key:        key,
+		}
+		return bot.executeScene(scene, sceneCtx)
+	}
+	return false, ErrSceneNotFound
+}
+
+func (bot *Bot[T]) executeScene(scene *Scene[T], ctx *SceneContext) (bool, error) {
+	if ctx.MsgContext == nil || ctx.sess.Scene == "" {
+		return false, nil
+	}
+	text := ctx.Msg.Text
+	if text == "" {
+		text = ctx.Msg.Caption
+	}
+	text = strings.TrimSpace(text)
+	prefix, cmd, args := bot.parseCommand(text)
+	if cmd != "" {
+		ctx.Prefix = prefix
+		ctx.Text = args
+		ctx.Args = strings.Fields(args)
+
+		res, matched, err := scene.executeCommand(cmd, ctx, bot.dbContext)
+		if err != nil {
+			return false, err
+		}
+		if matched {
+			return bot.applySceneResult(scene, ctx, res)
+		}
+	}
+	ctx.Text = text
+	ctx.Args = nil
+	ctx.Prefix = ""
+	if ctx.sess.Step != "" {
+		res, matched, err := scene.executeStep(ctx.sess.Step, ctx, bot.dbContext)
+		if err != nil {
+			return false, err
+		}
+		if matched {
+			return bot.applySceneResult(scene, ctx, res)
+		}
+	}
+
+	res, matched, err := scene.executeMessage(ctx, bot.dbContext)
+	if err != nil {
+		return false, err
+	}
+	if matched {
+		return bot.applySceneResult(scene, ctx, res)
+	}
+
+	return false, nil
+}
+func (bot *Bot[T]) applySceneResult(scene *Scene[T], ctx *SceneContext, result SceneResult) (bool, error) {
+	switch result.Action {
+	case SceneActionStay:
+		if err := bot.sessionStore.Set(ctx.key, ctx.sess); err != nil {
+			return false, err
+		}
+		return true, nil
+
+	case SceneActionNext:
+		if result.Next == "" {
+			return false, ErrSceneStepNotFound
+		}
+		if _, ok := scene.steps[result.Next]; !ok {
+			return false, ErrSceneStepNotFound
+		}
+		ctx.sess.Step = result.Next
+		if err := bot.sessionStore.Set(ctx.key, ctx.sess); err != nil {
+			return false, err
+		}
+		return true, nil
+
+	case SceneActionExit:
+		if err := bot.sessionStore.Delete(ctx.key); err != nil {
+			return false, err
+		}
+		return true, nil
+
+	case SceneActionPass:
+		return false, nil
+
+	default:
+		return false, nil
+	}
+}
+func buildSceneKey(scope SceneScope, ctx *MsgContext) (string, bool) {
+	switch scope {
+	case SceneScopeUserChat:
+		return fmt.Sprintf("user_id:%d:chat_id:%d", ctx.FromID, ctx.Msg.Chat.ID), true
+	case SceneScopeChat:
+		return fmt.Sprintf("chat_id:%d", ctx.Msg.Chat.ID), true
+	case SceneScopeUser:
+		return fmt.Sprintf("user_id:%d", ctx.FromID), true
+	default:
+		return "", false
+	}
+}

split.go

@@ -0,0 +1,44 @@
+package laniakea
+
+// SplitMessageText splits plain text into Telegram-safe message chunks.
+//
+// The function preserves the original text exactly: concatenating all returned
+// chunks reconstructs text byte-for-byte. It prefers splitting at newlines or
+// spaces within the Telegram message limit and falls back to hard rune-based
+// splits when no separator is available.
+func SplitMessageText(text string) []string {
+	return splitTextByLimit(text, maxMessageTextLen)
+}
+
+func splitTextByLimit(text string, limit int) []string {
+	if text == "" {
+		return nil
+	}
+
+	runes := []rune(text)
+	chunks := make([]string, 0, len(runes)/limit+1)
+
+	for start := 0; start < len(runes); {
+		end := start + limit
+		if end >= len(runes) {
+			chunks = append(chunks, string(runes[start:]))
+			break
+		}
+
+		splitAt := -1
+		for i := end - 1; i > start; i-- {
+			if runes[i] == '\n' || runes[i] == ' ' {
+				splitAt = i + 1
+				break
+			}
+		}
+		if splitAt == -1 {
+			splitAt = end
+		}
+
+		chunks = append(chunks, string(runes[start:splitAt]))
+		start = splitAt
+	}
+
+	return chunks
+}

tgapi/chat_types.go

@@ -224,7 +224,7 @@ type ChatBoostSource struct {
 // ChatBoost represents a boost added to a chat.
 // See https://core.telegram.org/bots/api#chatboost
 type ChatBoost struct {
-	BoostID        int             `json:"boost_id"`
+	BoostID        string          `json:"boost_id"`
 	AddDate        int             `json:"add_date"`
 	ExpirationDate int             `json:"expiration_date"`
 	Source         ChatBoostSource `json:"source"`

tgapi/types_test.go

@@ -37,9 +37,28 @@ func TestUpdateUnmarshalSetsType(t *testing.T) {
 			}`,
 			want: UpdateTypeCallbackQuery,
 		},
+		{
+			name: "chat boost",
+			body: `{
+				"update_id": 3,
+				"chat_boost": {
+					"chat": {"id": -1001, "type": "supergroup", "title": "Boosted"},
+					"boost": {
+						"boost_id": "boost-1",
+						"add_date": 1735689600,
+						"expiration_date": 1738291600,
+						"source": {
+							"source": "premium",
+							"user": {"id": 1, "is_bot": false, "first_name": "Test"}
+						}
+					}
+				}
+			}`,
+			want: UpdateTypeChatBoost,
+		},
 		{
 			name: "unknown",
-			body: `{"update_id":3}`,
+			body: `{"update_id":4}`,
 			want: UpdateTypeUnknown,
 		},
 	}
@@ -53,6 +72,9 @@ func TestUpdateUnmarshalSetsType(t *testing.T) {
 			if update.Type != tt.want {
 				t.Fatalf("unexpected update type: got %q want %q", update.Type, tt.want)
 			}
+			if tt.want == UpdateTypeChatBoost && update.ChatBoost.Boost.BoostID != "boost-1" {
+				t.Fatalf("unexpected boost id: got %q want %q", update.ChatBoost.Boost.BoostID, "boost-1")
+			}
 		})
 	}
 }

utils/version.go

@@ -2,7 +2,7 @@ package utils
 
 const (
 	// VersionString is the module version string.
-	VersionString = "1.0.0-rc.10"
+	VersionString = "1.0.0-rc.12"
 	// VersionMajor is the module major version.
 	VersionMajor = 1
 	// VersionMinor is the module minor version.
@@ -10,5 +10,5 @@ const (
 	// VersionPatch is the module patch version.
 	VersionPatch = 0
 	// VersionBeta is the prerelease counter for the current version.
-	VersionBeta = 10
+	VersionBeta = 12
 )