Receive images in WhatsApp batches

[onechat] / telegram.go

diff --git a/telegram.go b/telegram.go
index 4c16211c85dd4311d499593598b39a7649186c05..a595b68fd0d1756efc0b520e4c15d17781386c6a 100644 (file)
--- a/telegram.go
+++ b/telegram.go
@@ -7,7 +7,7 @@ import (
        "errors"
        "fmt"
        "io"
        "errors"
        "fmt"
        "io"

-       "log"
+       "log/slog"

        "net/http"
        "os"
        "path/filepath"
        "net/http"
        "os"
        "path/filepath"


@@ -73,8 +73,10 @@ func loadTelegramConfig(dir string) (TelegramConfig, bool, error) {
        }
 
        var config TelegramConfig
        }
 
        var config TelegramConfig

+

        decoder := json.NewDecoder(bytes.NewReader(data))
        decoder.DisallowUnknownFields()
        decoder := json.NewDecoder(bytes.NewReader(data))
        decoder.DisallowUnknownFields()

+

        err = decoder.Decode(&config)
        if err == nil && !errors.Is(decoder.Decode(&struct{}{}), io.EOF) {
                err = errors.New("data after the JSON object")
        err = decoder.Decode(&config)
        if err == nil && !errors.Is(decoder.Decode(&struct{}{}), io.EOF) {
                err = errors.New("data after the JSON object")


@@ -95,7 +97,7 @@ func loadTelegramConfig(dir string) (TelegramConfig, bool, error) {
 // newTelegramBot returns the bot of owner on api. The offset file is at
 // offsetPath, and logger gets the failures. No log line holds the text of a
 // message.
 // newTelegramBot returns the bot of owner on api. The offset file is at
 // offsetPath, and logger gets the failures. No log line holds the text of a
 // message.

-func newTelegramBot(api *TelegramAPI, owner int64, offsetPath string, logger *log.Logger) *TelegramBot {
+func newTelegramBot(api *TelegramAPI, owner int64, offsetPath string, logger *slog.Logger) *TelegramBot {

        return &TelegramBot{
                api:        api,
                owner:      owner,
        return &TelegramBot{
                api:        api,
                owner:      owner,


@@ -131,13 +133,13 @@ func (c TelegramConfig) validate() error {
 }
 
 // TelegramBot connects the private chat of the owner with the agent. It polls
 }
 
 // TelegramBot connects the private chat of the owner with the agent. It polls

-// the Bot API for new messages and sends each text message of the owner to the
-// agent. It ignores every other update. Its sender sends the replies, the
-// errors, the notices of the bot, and the user messages of the other clients to
-// the chat, and shows the typing action while a turn runs. Only the replies
-// have a format: their Markdown goes as rich messages, which Telegram renders
-// itself, and as message entities only when Telegram refuses a rich message.
-// The rest is plain text. Tool calls do not go to the chat.
+// the Bot API for new messages and sends owner text and images to the agent. It
+// ignores every other update. Its sender sends the replies, the errors, the
+// notices of the bot, and the user messages of the other clients to the chat,
+// and shows the typing action while a turn runs. Only the replies have a
+// format: their Markdown goes as rich messages, which Telegram renders itself,
+// and as message entities only when Telegram refuses a rich message. The rest
+// is plain text. Tool calls do not go to the chat.

 //
 // The offset file holds the ID of the next update. It moves past an update
 // only after the message of the update is durable in the log, so a restart
 //
 // The offset file holds the ID of the next update. It moves past an update
 // only after the message of the update is durable in the log, so a restart


@@ -145,12 +147,14 @@ func (c TelegramConfig) validate() error {
 // makes Telegram send the update again, and the message repeats once.
 //
 // A failed Bot API call waits and tries again, from minWait up to maxWait, or
 // makes Telegram send the update again, and the message repeats once.
 //
 // A failed Bot API call waits and tries again, from minWait up to maxWait, or

-// as long as the Bot API asks. It never stops the agent.
+// as long as the Bot API asks. It never stops the agent. A TelegramOutage logs
+// the first failure and the end of each run of failures, and the retries
+// between them log nothing.

 type TelegramBot struct {
        api        *TelegramAPI
        owner      int64
        offsetPath string
 type TelegramBot struct {
        api        *TelegramAPI
        owner      int64
        offsetPath string

-       logger     *log.Logger
+       logger     *slog.Logger

        minWait    time.Duration
        maxWait    time.Duration
 
        minWait    time.Duration
        maxWait    time.Duration
 


@@ -160,10 +164,15 @@ type TelegramBot struct {
 }
 
 // Notify queues event for the chat. It never blocks, so a slow network does not
 }
 
 // Notify queues event for the chat. It never blocks, so a slow network does not

-// stop the agent.
+// stop the agent. The WhatsApp batches and the runs of the schedules do not go
+// to the chat: the reply of the agent tells the user what needs the user.

 func (b *TelegramBot) Notify(event Event) {
        switch event.Kind {
 func (b *TelegramBot) Notify(event Event) {
        switch event.Kind {

-       case "busy", "idle", "reply", "error", "notice":
+       case "busy", "idle", "reply", "error", "notice", "subagent":
+       case "work":
+               if event.Source == whatsappSource || event.Source == scheduleSource {
+                       return
+               }

        case "user":
                if event.Source == telegramSource {
                        return
        case "user":
                if event.Source == telegramSource {
                        return


@@ -173,6 +182,7 @@ func (b *TelegramBot) Notify(event Event) {
        }
 
        b.mutex.Lock()
        }
 
        b.mutex.Lock()

+

        b.queue = append(b.queue, event)
        b.mutex.Unlock()
 
        b.queue = append(b.queue, event)
        b.mutex.Unlock()
 


@@ -183,21 +193,24 @@ func (b *TelegramBot) Notify(event Event) {
 }
 
 // Run polls for the messages of the owner and sends the queued events to the
 }
 
 // Run polls for the messages of the owner and sends the queued events to the

-// chat until ctx ends. It returns an error only when a message or the offset
-// cannot be written, because then the bot would lose or repeat messages.
-func (b *TelegramBot) Run(ctx context.Context, l *loop) error {
+// chat until ctx ends. It returns an error only when a message or the offset or
+// image cannot be written, because then the bot would lose or repeat messages.
+func (b *TelegramBot) Run(ctx context.Context, l *TurnLoop, whatsapp *WhatsApp) error {

        ctx, cancel := context.WithCancel(ctx)
        defer cancel()
 
        var sender sync.WaitGroup
        ctx, cancel := context.WithCancel(ctx)
        defer cancel()
 
        var sender sync.WaitGroup

+

        sender.Add(1)
        sender.Add(1)

+

        go func() {
                defer sender.Done()
 
                b.send(ctx)
        }()
 
        go func() {
                defer sender.Done()
 
                b.send(ctx)
        }()
 

-       err := b.poll(ctx, l)
+       err := b.poll(ctx, l, whatsapp)
+

        cancel()
        sender.Wait()
 
        cancel()
        sender.Wait()
 


@@ -230,6 +243,7 @@ func (b *TelegramBot) send(ctx context.Context) {
                switch event.Kind {
                case "busy":
                        busy = true
                switch event.Kind {
                case "busy":
                        busy = true

+

                        b.typing(ctx)
                        ticker.Reset(telegramTypingInterval)
                case "idle":
                        b.typing(ctx)
                        ticker.Reset(telegramTypingInterval)
                case "idle":


@@ -244,16 +258,31 @@ func (b *TelegramBot) send(ctx context.Context) {
        }
 }
 
        }
 }
 

-// poll gets the updates from the stored offset on and handles each one, until
-// ctx ends. Each update is handled to its end also when ctx ends during it, so
-// a stop does not repeat its message.
-func (b *TelegramBot) poll(ctx context.Context, l *loop) error {
+// poll gets updates from the stored offset and handles them until ctx ends. A
+// failed image download retries from the same offset. A submitted message is
+// flushed even if ctx ends, and only then can the offset advance.
+func (b *TelegramBot) poll(ctx context.Context, l *TurnLoop, whatsapp *WhatsApp) error {

        offset, err := telegramLoadOffset(b.offsetPath)
        if err != nil {
                return err
        }
 
        offset, err := telegramLoadOffset(b.offsetPath)
        if err != nil {
                return err
        }
 

+       outage := &TelegramOutage{
+               logger: b.logger,
+               loss:   "receive failed",
+               back:   "receive back",
+       }
+
+       imageOutage := &TelegramOutage{
+               logger: b.logger,
+               loss:   "image receive failed",
+               back:   "image receive back",
+       }
+
+       imageWait := b.minWait

        wait := b.minWait
        wait := b.minWait

+
+poll:

        for ctx.Err() == nil {
                updates, err := b.api.GetUpdates(ctx, offset)
                if ctx.Err() != nil {
        for ctx.Err() == nil {
                updates, err := b.api.GetUpdates(ctx, offset)
                if ctx.Err() != nil {


@@ -262,22 +291,35 @@ func (b *TelegramBot) poll(ctx context.Context, l *loop) error {
 
                if err != nil {
                        _, asked := telegramRetryable(err)
 
                if err != nil {
                        _, asked := telegramRetryable(err)

-                       wait = b.pause(ctx, err, wait, asked)
+                       wait = b.pause(ctx, outage, err, wait, asked)

 
                        continue
                }
 
 
                        continue
                }
 

+               outage.End()
+

                wait = b.minWait
                wait = b.minWait

+

                for _, update := range updates {
                        if ctx.Err() != nil {
                                return nil
                        }
 
                for _, update := range updates {
                        if ctx.Err() != nil {
                                return nil
                        }
 

-                       err = b.handle(context.WithoutCancel(ctx), l, update)
+                       err = b.handle(ctx, l, whatsapp, update)

                        if err != nil {
                        if err != nil {

+                               retry, asked := telegramRetryable(err)
+                               if retry {
+                                       imageWait = b.pause(ctx, imageOutage, err, imageWait, asked)
+                                       continue poll
+                               }
+

                                return err
                        }
 
                                return err
                        }
 

+                       imageOutage.End()
+
+                       imageWait = b.minWait
+

                        offset = update.UpdateID + 1
                        err = telegramSaveOffset(b.offsetPath, offset)
                        if err != nil {
                        offset = update.UpdateID + 1
                        err = telegramSaveOffset(b.offsetPath, offset)
                        if err != nil {


@@ -311,8 +353,9 @@ func (b *TelegramBot) typing(ctx context.Context) {
 }
 
 // post sends event to the chat. A reply goes as rich messages of its Markdown,
 }
 
 // post sends event to the chat. A reply goes as rich messages of its Markdown,

-// split with telegramSplitRich. Every other event goes as plain text, split
-// with telegramSplitMessage.
+// with each < and & outside code escaped by telegramEscapeTags and then split
+// with telegramSplitRich, so that the length limit counts the escaped text.
+// Every other event goes as plain text, split with telegramSplitMessage.

 func (b *TelegramBot) post(ctx context.Context, event Event) {
        if event.Kind != "reply" {
                for _, text := range telegramSplitMessage(telegramText(event), telegramMessageUnits) {
 func (b *TelegramBot) post(ctx context.Context, event Event) {
        if event.Kind != "reply" {
                for _, text := range telegramSplitMessage(telegramText(event), telegramMessageUnits) {


@@ -324,16 +367,16 @@ func (b *TelegramBot) post(ctx context.Context, event Event) {
                return
        }
 
                return
        }
 

-       for _, markdown := range telegramSplitRich(event.Text, telegramRichBytes) {
+       for _, markdown := range telegramSplitRich(telegramEscapeTags(event.Text), telegramRichBytes) {

                b.deliverRich(ctx, markdown)
        }
 }
 
                b.deliverRich(ctx, markdown)
        }
 }
 

-// pause logs err and waits the longer of wait and asked, or until ctx ends. It
-// returns the wait of the next failure: twice wait, up to maxWait.
-func (b *TelegramBot) pause(ctx context.Context, err error, wait, asked time.Duration) time.Duration {
+// pause gives err to outage and waits the longer of wait and asked, or until
+// ctx ends. It returns the wait of the next failure: twice wait, up to maxWait.
+func (b *TelegramBot) pause(ctx context.Context, outage *TelegramOutage, err error, wait, asked time.Duration) time.Duration {

        delay := max(wait, asked)
        delay := max(wait, asked)

-       b.logger.Printf("%v (next try in %s)", err, delay)
+       outage.Fail(err, delay)

 
        timer := time.NewTimer(delay)
        defer timer.Stop()
 
        timer := time.NewTimer(delay)
        defer timer.Stop()


@@ -348,30 +391,81 @@ func (b *TelegramBot) pause(ctx context.Context, err error, wait, asked time.Dur
 
 // handle runs one update. A text message of the owner in the private chat goes
 // to the agent, and handle returns when it is durable in the log. The line
 
 // handle runs one update. A text message of the owner in the private chat goes
 // to the agent, and handle returns when it is durable in the log. The line

-// /stop interrupts the turn. Any other message of the owner gets the answer
-// that only text is supported. Every other update is ignored, and its content
-// is not logged.
-func (b *TelegramBot) handle(ctx context.Context, l *loop, update TelegramUpdate) error {
+// /stop interrupts the turn, the line /stop NAME stops the subagent NAME, and a
+// line that starts with /whatsapp runs a WhatsApp command on whatsapp, whose
+// answers go to the chat only. Photos and image documents enter the shared
+// image store with their caption. Other media keep the text-only answer. Every
+// other update is ignored, and its content is not logged.
+func (b *TelegramBot) handle(ctx context.Context, l *TurnLoop, whatsapp *WhatsApp, update TelegramUpdate) error {

        message := update.Message
        if message == nil || message.Chat.Type != "private" || message.Chat.ID != b.owner || message.From == nil || message.From.ID != b.owner {
        message := update.Message
        if message == nil || message.Chat.Type != "private" || message.Chat.ID != b.owner || message.From == nil || message.From.ID != b.owner {

-               b.logger.Print("update ignored: not a message of the owner in the private chat")
+               b.logger.Info("message ignored: not from the owner")
+

                return nil
        }
 
                return nil
        }
 

+       name, stop := stopSubagentName(message.Text)
+       args, isWhatsApp := whatsappCommandArgs(message.Text)

        switch {
        switch {

+       case len(message.Photo) > 0 || message.Document != nil:
+               text, err := telegramImageText(ctx, b.api, l.agent.Images(), message)
+               if err != nil {
+                       retry, _ := telegramRetryable(err)
+                       if retry {
+                               return fmt.Errorf("receive image: %w", err)
+                       }
+
+                       switch {
+                       case errors.Is(err, errTelegramOtherMedia):
+                               b.notice(telegramTextOnly)
+                       case errors.Is(err, errImageSize), errors.Is(err, errImageFormat), errors.Is(err, errTelegramPhotoSize):
+                               b.notice(err.Error())
+                       default:
+                               var answer *TelegramError
+
+                               if !errors.As(err, &answer) {
+                                       return fmt.Errorf("receive Telegram image: %w", err)
+                               }
+
+                               b.notice("Cannot download image.")
+                       }
+
+                       return nil
+               }
+
+               _, err = l.Submit(telegramSource, text)
+               if err != nil {
+                       return fmt.Errorf("submit Telegram image: %w", err)
+               }
+
+               err = l.Flush(context.WithoutCancel(ctx))
+               if err != nil {
+                       return fmt.Errorf("flush Telegram image: %w", err)
+               }

        case message.Text == "":
                b.notice(telegramTextOnly)
        case strings.TrimSpace(message.Text) == stopCommand:
                if !l.Interrupt() {
                        b.notice("No turn runs.")
                }
        case message.Text == "":
                b.notice(telegramTextOnly)
        case strings.TrimSpace(message.Text) == stopCommand:
                if !l.Interrupt() {
                        b.notice("No turn runs.")
                }

+       case stop:
+               found, err := l.StopSubagent(name)
+               if err != nil {
+                       return fmt.Errorf("stop subagent %s: %w", name, err)
+               }
+
+               if !found {
+                       b.notice("No subagent " + name + " runs.")
+               }
+       case isWhatsApp:
+               whatsapp.Command(args, b.notice)

        default:
                _, err := l.Submit(telegramSource, message.Text)
                if err != nil {
                        return err
                }
 
        default:
                _, err := l.Submit(telegramSource, message.Text)
                if err != nil {
                        return err
                }
 

-               err = l.Flush(ctx)
+               err = l.Flush(context.WithoutCancel(ctx))

                if err != nil {
                        return fmt.Errorf("flush the message from Telegram: %w", err)
                }
                if err != nil {
                        return fmt.Errorf("flush the message from Telegram: %w", err)
                }


@@ -385,60 +479,86 @@ func (b *TelegramBot) handle(ctx context.Context, l *loop, update TelegramUpdate
 // reply is not lost to a bad entity. It tries again after each failure that a
 // later try can fix, until ctx ends. It drops the part after any other failure.
 func (b *TelegramBot) deliver(ctx context.Context, part TelegramPart) {
 // reply is not lost to a bad entity. It tries again after each failure that a
 // later try can fix, until ctx ends. It drops the part after any other failure.
 func (b *TelegramBot) deliver(ctx context.Context, part TelegramPart) {

+       outage := b.sendOutage()

        wait := b.minWait
        for {
                err := b.api.SendMessage(ctx, b.owner, part.text, part.entities)
        wait := b.minWait
        for {
                err := b.api.SendMessage(ctx, b.owner, part.text, part.entities)

+               retry, asked := telegramRetryable(err)
+               if !retry {
+                       outage.End()
+               }
+

                if err == nil || ctx.Err() != nil {
                        return
                }
 
                var answer *TelegramError
                if err == nil || ctx.Err() != nil {
                        return
                }
 
                var answer *TelegramError

+

                if len(part.entities) > 0 && errors.As(err, &answer) && answer.Status == http.StatusBadRequest {
                if len(part.entities) > 0 && errors.As(err, &answer) && answer.Status == http.StatusBadRequest {

-                       b.logger.Printf("entities refused, the message goes again as plain text: %v", err)
+                       b.logger.Warn("reply sent as plain text", "err", err)
+

                        part.entities = nil
 
                        continue
                }
 
                        part.entities = nil
 
                        continue
                }
 

-               retry, asked := telegramRetryable(err)

                if !retry {
                if !retry {

-                       b.logger.Printf("message dropped: %v", err)
+                       b.logger.Error("reply lost", "err", err)
+

                        return
                }
 
                        return
                }
 

-               wait = b.pause(ctx, err, wait, asked)
+               wait = b.pause(ctx, outage, err, wait, asked)

        }
 }
 
        }
 }
 

-// deliverRich sends markdown to the chat as a rich message. When the Bot API
-// refuses it with HTTP 400 or 404, the message was not sent, so deliverRich
-// sends the same Markdown once with message entities, and the reply is not
-// lost and does not repeat. It tries again after each failure that a later try
-// can fix, until ctx ends. It drops the message after any other failure.
+// deliverRich sends markdown, escaped with telegramEscapeTags, to the chat as a
+// rich message. When the Bot API refuses it with HTTP 400 or 404, the message
+// was not sent, so deliverRich sends the text of the part once with message
+// entities, and the reply is not lost and does not repeat. Message entities
+// read no HTML, so the fallback gets the Markdown of telegramUnescapeTags, as
+// the model wrote it. It tries again after each failure that a later try can
+// fix, until ctx ends. It drops the message after any other failure.

 func (b *TelegramBot) deliverRich(ctx context.Context, markdown string) {
 func (b *TelegramBot) deliverRich(ctx context.Context, markdown string) {

+       outage := b.sendOutage()

        wait := b.minWait
        for {
                err := b.api.SendRichMessage(ctx, b.owner, markdown)
        wait := b.minWait
        for {
                err := b.api.SendRichMessage(ctx, b.owner, markdown)

+               retry, asked := telegramRetryable(err)
+               if !retry {
+                       outage.End()
+               }
+

                if err == nil || ctx.Err() != nil {
                        return
                }
 
                if telegramRejected(err) {
                if err == nil || ctx.Err() != nil {
                        return
                }
 
                if telegramRejected(err) {

-                       b.logger.Printf("rich message refused, the reply goes with entities: %v", err)
-                       for _, part := range telegramReplyParts(markdown) {
+                       b.logger.Warn("reply sent with simple formatting", "err", err)
+
+                       for _, part := range telegramReplyParts(telegramUnescapeTags(markdown)) {

                                b.deliver(ctx, part)
                        }
 
                        return
                }
 
                                b.deliver(ctx, part)
                        }
 
                        return
                }
 

-               retry, asked := telegramRetryable(err)

                if !retry {
                if !retry {

-                       b.logger.Printf("message dropped: %v", err)
+                       b.logger.Error("reply lost", "err", err)
+

                        return
                }
 
                        return
                }
 

-               wait = b.pause(ctx, err, wait, asked)
+               wait = b.pause(ctx, outage, err, wait, asked)
+       }
+}
+
+// sendOutage returns a new outage of the messages to the chat.
+func (b *TelegramBot) sendOutage() *TelegramOutage {
+       return &TelegramOutage{
+               logger: b.logger,
+               loss:   "send failed",
+               back:   "send back",

        }
 }
 
        }
 }
 


@@ -450,6 +570,38 @@ func (b *TelegramBot) notice(text string) {
        })
 }
 
        })
 }
 

+// TelegramOutage is one run of failures of a kind of Bot API call. The first
+// failure logs loss, its cause, and the wait of the next try. The retries log
+// nothing. The next answer of Telegram logs back and the length of the outage.
+// loss and back say what the user loses and gets again.
+type TelegramOutage struct {
+       logger *slog.Logger
+       loss   string
+       back   string
+       start  time.Time
+}
+
+// Fail logs the start of an outage with err and delay, unless an outage runs.
+func (o *TelegramOutage) Fail(err error, delay time.Duration) {
+       if !o.start.IsZero() {
+               return
+       }
+
+       o.start = time.Now()
+       o.logger.Warn(o.loss, "err", err, "retry", delay)
+}
+
+// End logs the end of the outage that runs, with its length.
+func (o *TelegramOutage) End() {
+       if o.start.IsZero() {
+               return
+       }
+
+       o.logger.Info(o.back, "after", time.Since(o.start))
+
+       o.start = time.Time{}
+}
+

 // TelegramPart is the text of one message to the chat, at most
 // telegramMessageUnits long, and its entities.
 type TelegramPart struct {
 // TelegramPart is the text of one message to the chat, at most
 // telegramMessageUnits long, and its entities.
 type TelegramPart struct {


@@ -475,6 +627,7 @@ func telegramLoadOffset(path string) (int64, error) {
        }
 
        var file TelegramOffsetFile
        }
 
        var file TelegramOffsetFile

+

        err = json.Unmarshal(data, &file)
        if err != nil {
                return 0, fmt.Errorf("%s: %w", path, err)
        err = json.Unmarshal(data, &file)
        if err != nil {
                return 0, fmt.Errorf("%s: %w", path, err)


@@ -506,6 +659,7 @@ func telegramSaveOffset(path string, offset int64) error {
 // never cuts a character.
 func telegramSplitMessage(text string, limit int) []string {
        var parts []string
 // never cuts a character.
 func telegramSplitMessage(text string, limit int) []string {
        var parts []string

+

        for {
                end := telegramPrefixEnd(text, limit)
                if end == len(text) {
        for {
                end := telegramPrefixEnd(text, limit)
                if end == len(text) {


@@ -527,11 +681,17 @@ func telegramSplitMessage(text string, limit int) []string {
 }
 
 // telegramText returns the text of event for the chat. A user message of
 }
 
 // telegramText returns the text of event for the chat. A user message of

-// another client has its source as a mark.
+// another client has its source as a mark. A subagent shows only its start and
+// how its run ended, because the reply of the agent carries the content of the
+// report.

 func telegramText(event Event) string {
        switch event.Kind {
        case "user":
                return "[" + event.Source + "] " + event.Text
 func telegramText(event Event) string {
        switch event.Kind {
        case "user":
                return "[" + event.Source + "] " + event.Text

+       case "subagent":
+               return "[" + event.Text + "] started"
+       case "work":
+               return "[" + event.Source + "] " + event.Status

        case "error":
                return "Error: " + event.Text
        default:
        case "error":
                return "Error: " + event.Text
        default:


@@ -545,9 +705,11 @@ func telegramText(event Event) string {
 // after the last line break outside a code block, then after the last line
 // break in a code block, which it closes at the end of the part and opens again
 // in the next part with the same fence line. A line longer than limit is cut at
 // after the last line break outside a code block, then after the last line
 // break in a code block, which it closes at the end of the part and opens again
 // in the next part with the same fence line. A line longer than limit is cut at

-// the limit. It never cuts a character.
+// the limit, or before an & in the four bytes before the limit, so that it does
+// not cut an entity of telegramEscapeTags. It never cuts a character.

 func telegramSplitRich(markdown string, limit int) []string {
        var parts []string
 func telegramSplitRich(markdown string, limit int) []string {
        var parts []string

+

        for len(markdown) > limit {
                cut, fence, opening := telegramRichCut(markdown, limit)
                if fence == "" {
        for len(markdown) > limit {
                cut, fence, opening := telegramRichCut(markdown, limit)
                if fence == "" {


@@ -603,7 +765,9 @@ func telegramPrefixEnd(text string, limit int) int {
 // so each cut makes the rest shorter.
 func telegramRichCut(markdown string, limit int) (int, string, string) {
        blank, line, code := 0, 0, 0
 // so each cut makes the rest shorter.
 func telegramRichCut(markdown string, limit int) (int, string, string) {
        blank, line, code := 0, 0, 0

+

        var fence, opening, inFence, inOpening string
        var fence, opening, inFence, inOpening string

+

        for start := 0; start < limit; {
                end := strings.IndexByte(markdown[start:], '\n')
                if end < 0 || start+end+1 > limit {
        for start := 0; start < limit; {
                end := strings.IndexByte(markdown[start:], '\n')
                if end < 0 || start+end+1 > limit {


@@ -612,10 +776,10 @@ func telegramRichCut(markdown string, limit int) (int, string, string) {
 
                end += start + 1
                text := strings.TrimRight(markdown[start:end], "\r\n")
 
                end += start + 1
                text := strings.TrimRight(markdown[start:end], "\r\n")

-               _, opens := telegramCodeFence(text)
+               _, opens := markdownCodeFence(text)

                switch {
                case fence != "":
                switch {
                case fence != "":

-                       if telegramClosesFence(text, fence) {
+                       if markdownClosesFence(text, fence) {

                                fence = ""
                        } else if end > len(opening)+1 && end+len(fence)+1 <= limit {
                                code, inFence, inOpening = end, fence, opening
                                fence = ""
                        } else if end > len(opening)+1 && end+len(fence)+1 <= limit {
                                code, inFence, inOpening = end, fence, opening


@@ -648,6 +812,12 @@ func telegramRichCut(markdown string, limit int) (int, string, string) {
                cut--
        }
 
                cut--
        }
 

+       start := max(cut-len("&amp;")+1, 0)
+       entity := strings.LastIndexByte(markdown[start:cut], '&')
+       if entity >= 0 && start+entity > 0 {
+               cut = start + entity
+       }
+

        return cut, "", ""
 }
 
        return cut, "", ""
 }
 


@@ -656,10 +826,13 @@ func telegramRichCut(markdown string, limit int) (int, string, string) {
 // An entity that crosses a cut becomes one entity in each part.
 func telegramSplitEntities(text string, entities []TelegramEntity, limit int) []TelegramPart {
        var parts []TelegramPart
 // An entity that crosses a cut becomes one entity in each part.
 func telegramSplitEntities(text string, entities []TelegramEntity, limit int) []TelegramPart {
        var parts []TelegramPart

+

        start := 0
        for _, part := range telegramSplitMessage(text, limit) {
                end := start + telegramUTF16Units(part)
        start := 0
        for _, part := range telegramSplitMessage(text, limit) {
                end := start + telegramUTF16Units(part)

+

                var kept []TelegramEntity
                var kept []TelegramEntity

+

                for _, entity := range entities {
                        from := max(entity.Offset, start)
                        to := min(entity.Offset+entity.Length, end)
                for _, entity := range entities {
                        from := max(entity.Offset, start)
                        to := min(entity.Offset+entity.Length, end)