hermes-agent/gateway/stream_consumer.py

"""Gateway streaming consumer — bridges sync agent callbacks to async platform delivery.

The agent fires stream_delta_callback(text) synchronously from its worker thread.
GatewayStreamConsumer:
  1. Receives deltas via on_delta() (thread-safe, sync)
  2. Queues them to an asyncio task via queue.Queue
  3. The async run() task buffers, rate-limits, and progressively edits
     a single message on the target platform

Design: Uses the edit transport (send initial message, then editMessageText).
This is universally supported across Telegram, Discord, and Slack.

Credit: jobless0x (#774, #1312), OutThisLife (#798), clicksingh (#697).
"""

from __future__ import annotations

import asyncio
import logging
import queue
import re
import time
from dataclasses import dataclass
from typing import Any, Optional

logger = logging.getLogger("gateway.stream_consumer")

# Sentinel to signal the stream is complete
_DONE = object()

# Sentinel to signal a tool boundary — finalize current message and start a
# new one so that subsequent text appears below tool progress messages.
_NEW_SEGMENT = object()

# Queue marker for a completed assistant commentary message emitted between
# API/tool iterations (for example: "I'll inspect the repo first.").
_COMMENTARY = object()


@dataclass
class StreamConsumerConfig:
    """Runtime config for a single stream consumer instance."""
    edit_interval: float = 1.0
    buffer_threshold: int = 40
    cursor: str = " ▉"


class GatewayStreamConsumer:
    """Async consumer that progressively edits a platform message with streamed tokens.

    Usage::

        consumer = GatewayStreamConsumer(adapter, chat_id, config, metadata=metadata)
        # Pass consumer.on_delta as stream_delta_callback to AIAgent
        agent = AIAgent(..., stream_delta_callback=consumer.on_delta)
        # Start the consumer as an asyncio task
        task = asyncio.create_task(consumer.run())
        # ... run agent in thread pool ...
        consumer.finish()  # signal completion
        await task         # wait for final edit
    """

    # After this many consecutive flood-control failures, permanently disable
    # progressive edits for the remainder of the stream.
    _MAX_FLOOD_STRIKES = 3

    def __init__(
        self,
        adapter: Any,
        chat_id: str,
        config: Optional[StreamConsumerConfig] = None,
        metadata: Optional[dict] = None,
    ):
        self.adapter = adapter
        self.chat_id = chat_id
        self.cfg = config or StreamConsumerConfig()
        self.metadata = metadata
        self._queue: queue.Queue = queue.Queue()
        self._accumulated = ""
        self._message_id: Optional[str] = None
        self._already_sent = False
        self._edit_supported = True  # Disabled when progressive edits are no longer usable
        self._last_edit_time = 0.0
        self._last_sent_text = ""   # Track last-sent text to skip redundant edits
        self._fallback_final_send = False
        self._fallback_prefix = ""
        self._flood_strikes = 0         # Consecutive flood-control edit failures
        self._current_edit_interval = self.cfg.edit_interval  # Adaptive backoff
        self._final_response_sent = False

    @property
    def already_sent(self) -> bool:
        """True if at least one message was sent or edited during the run."""
        return self._already_sent

    @property
    def final_response_sent(self) -> bool:
        """True when the stream consumer delivered the final assistant reply."""
        return self._final_response_sent

    def on_segment_break(self) -> None:
        """Finalize the current stream segment and start a fresh message."""
        self._queue.put(_NEW_SEGMENT)

    def on_commentary(self, text: str) -> None:
        """Queue a completed interim assistant commentary message."""
        if text:
            self._queue.put((_COMMENTARY, text))

    def _reset_segment_state(self, *, preserve_no_edit: bool = False) -> None:
        if preserve_no_edit and self._message_id == "__no_edit__":
            return
        self._message_id = None
        self._accumulated = ""
        self._last_sent_text = ""
        self._fallback_final_send = False
        self._fallback_prefix = ""

    def on_delta(self, text: str) -> None:
        """Thread-safe callback — called from the agent's worker thread.

        When *text* is ``None``, signals a tool boundary: the current message
        is finalized and subsequent text will be sent as a new message so it
        appears below any tool-progress messages the gateway sent in between.
        """
        if text:
            self._queue.put(text)
        elif text is None:
            self.on_segment_break()

    def finish(self) -> None:
        """Signal that the stream is complete."""
        self._queue.put(_DONE)

    async def run(self) -> None:
        """Async task that drains the queue and edits the platform message."""
        # Platform message length limit — leave room for cursor + formatting
        _raw_limit = getattr(self.adapter, "MAX_MESSAGE_LENGTH", 4096)
        _safe_limit = max(500, _raw_limit - len(self.cfg.cursor) - 100)

        try:
            while True:
                # Drain all available items from the queue
                got_done = False
                got_segment_break = False
                commentary_text = None
                while True:
                    try:
                        item = self._queue.get_nowait()
                        if item is _DONE:
                            got_done = True
                            break
                        if item is _NEW_SEGMENT:
                            got_segment_break = True
                            break
                        if isinstance(item, tuple) and len(item) == 2 and item[0] is _COMMENTARY:
                            commentary_text = item[1]
                            break
                        self._accumulated += item
                    except queue.Empty:
                        break

                # Decide whether to flush an edit
                now = time.monotonic()
                elapsed = now - self._last_edit_time
                should_edit = (
                    got_done
                    or got_segment_break
                    or commentary_text is not None
                    or (elapsed >= self._current_edit_interval
                        and self._accumulated)
                    or len(self._accumulated) >= self.cfg.buffer_threshold
                )

                current_update_visible = False
                if should_edit and self._accumulated:
                    # Split overflow: if accumulated text exceeds the platform
                    # limit, split into properly sized chunks.
                    if (
                        len(self._accumulated) > _safe_limit
                        and self._message_id is None
                    ):
                        # No existing message to edit (first message or after a
                        # segment break).  Use truncate_message — the same
                        # helper the non-streaming path uses — to split with
                        # proper word/code-fence boundaries and chunk
                        # indicators like "(1/2)".
                        chunks = self.adapter.truncate_message(
                            self._accumulated, _safe_limit
                        )
                        for chunk in chunks:
                            await self._send_new_chunk(chunk, self._message_id)
                        self._accumulated = ""
                        self._last_sent_text = ""
                        self._last_edit_time = time.monotonic()
                        if got_done:
                            self._final_response_sent = self._already_sent
                            return
                        if got_segment_break:
                            self._message_id = None
                            self._fallback_final_send = False
                            self._fallback_prefix = ""
                        continue

                    # Existing message: edit it with the first chunk, then
                    # start a new message for the overflow remainder.
                    while (
                        len(self._accumulated) > _safe_limit
                        and self._message_id is not None
                        and self._edit_supported
                    ):
                        split_at = self._accumulated.rfind("\n", 0, _safe_limit)
                        if split_at < _safe_limit // 2:
                            split_at = _safe_limit
                        chunk = self._accumulated[:split_at]
                        ok = await self._send_or_edit(chunk)
                        if self._fallback_final_send or not ok:
                            # Edit failed (or backed off due to flood control)
                            # while attempting to split an oversized message.
                            # Keep the full accumulated text intact so the
                            # fallback final-send path can deliver the remaining
                            # continuation without dropping content.
                            break
                        self._accumulated = self._accumulated[split_at:].lstrip("\n")
                        self._message_id = None
                        self._last_sent_text = ""

                    display_text = self._accumulated
                    if not got_done and not got_segment_break and commentary_text is None:
                        display_text += self.cfg.cursor

                    current_update_visible = await self._send_or_edit(display_text)
                    self._last_edit_time = time.monotonic()

                if got_done:
                    # Final edit without cursor. If progressive editing failed
                    # mid-stream, send a single continuation/fallback message
                    # here instead of letting the base gateway path send the
                    # full response again.
                    if self._accumulated:
                        if self._fallback_final_send:
                            await self._send_fallback_final(self._accumulated)
                        elif current_update_visible:
                            self._final_response_sent = True
                        elif self._message_id:
                            self._final_response_sent = await self._send_or_edit(self._accumulated)
                        elif not self._already_sent:
                            self._final_response_sent = await self._send_or_edit(self._accumulated)
                    return

                if commentary_text is not None:
                    self._reset_segment_state()
                    await self._send_commentary(commentary_text)
                    self._last_edit_time = time.monotonic()
                    self._reset_segment_state()

                # Tool boundary: reset message state so the next text chunk
                # creates a fresh message below any tool-progress messages.
                #
                # Exception: when _message_id is "__no_edit__" the platform
                # never returned a real message ID (e.g. Signal, webhook with
                # github_comment delivery).  Resetting to None would re-enter
                # the "first send" path on every tool boundary and post one
                # platform message per tool call — that is what caused 155
                # comments under a single PR.  Instead, preserve the sentinel
                # so the full continuation is delivered once via
                # _send_fallback_final.
                # (When editing fails mid-stream due to flood control the id is
                # a real string like "msg_1", not "__no_edit__", so that case
                # still resets and creates a fresh segment as intended.)
                if got_segment_break:
                    self._reset_segment_state(preserve_no_edit=True)

                await asyncio.sleep(0.05)  # Small yield to not busy-loop

        except asyncio.CancelledError:
            # Best-effort final edit on cancellation
            if self._accumulated and self._message_id:
                try:
                    await self._send_or_edit(self._accumulated)
                except Exception:
                    pass
        except Exception as e:
            logger.error("Stream consumer error: %s", e)

    # Pattern to strip MEDIA:<path> tags (including optional surrounding quotes).
    # Matches the simple cleanup regex used by the non-streaming path in
    # gateway/platforms/base.py for post-processing.
    _MEDIA_RE = re.compile(r'''[`"']?MEDIA:\s*\S+[`"']?''')

    @staticmethod
    def _clean_for_display(text: str) -> str:
        """Strip MEDIA: directives and internal markers from text before display.

        The streaming path delivers raw text chunks that may include
        ``MEDIA:<path>`` tags and ``[[audio_as_voice]]`` directives meant for
        the platform adapter's post-processing.  The actual media files are
        delivered separately via ``_deliver_media_from_response()`` after the
        stream finishes — we just need to hide the raw directives from the
        user.
        """
        if "MEDIA:" not in text and "[[audio_as_voice]]" not in text:
            return text
        cleaned = text.replace("[[audio_as_voice]]", "")
        cleaned = GatewayStreamConsumer._MEDIA_RE.sub("", cleaned)
        # Collapse excessive blank lines left behind by removed tags
        cleaned = re.sub(r'\n{3,}', '\n\n', cleaned)
        # Strip trailing whitespace/newlines but preserve leading content
        return cleaned.rstrip()

    async def _send_new_chunk(self, text: str, reply_to_id: Optional[str]) -> Optional[str]:
        """Send a new message chunk, optionally threaded to a previous message.

        Returns the message_id so callers can thread subsequent chunks.
        """
        text = self._clean_for_display(text)
        if not text.strip():
            return reply_to_id
        try:
            meta = dict(self.metadata) if self.metadata else {}
            result = await self.adapter.send(
                chat_id=self.chat_id,
                content=text,
                reply_to=reply_to_id,
                metadata=meta,
            )
            if result.success and result.message_id:
                self._message_id = str(result.message_id)
                self._already_sent = True
                self._last_sent_text = text
                return str(result.message_id)
            else:
                self._edit_supported = False
                return reply_to_id
        except Exception as e:
            logger.error("Stream send chunk error: %s", e)
            return reply_to_id

    def _visible_prefix(self) -> str:
        """Return the visible text already shown in the streamed message."""
        prefix = self._last_sent_text or ""
        if self.cfg.cursor and prefix.endswith(self.cfg.cursor):
            prefix = prefix[:-len(self.cfg.cursor)]
        return self._clean_for_display(prefix)

    def _continuation_text(self, final_text: str) -> str:
        """Return only the part of final_text the user has not already seen."""
        prefix = self._fallback_prefix or self._visible_prefix()
        if prefix and final_text.startswith(prefix):
            return final_text[len(prefix):].lstrip()
        return final_text

    @staticmethod
    def _split_text_chunks(text: str, limit: int) -> list[str]:
        """Split text into reasonably sized chunks for fallback sends."""
        if len(text) <= limit:
            return [text]
        chunks: list[str] = []
        remaining = text
        while len(remaining) > limit:
            split_at = remaining.rfind("\n", 0, limit)
            if split_at < limit // 2:
                split_at = limit
            chunks.append(remaining[:split_at])
            remaining = remaining[split_at:].lstrip("\n")
        if remaining:
            chunks.append(remaining)
        return chunks

    async def _send_fallback_final(self, text: str) -> None:
        """Send the final continuation after streaming edits stop working.

        Retries each chunk once on flood-control failures with a short delay.
        """
        final_text = self._clean_for_display(text)
        continuation = self._continuation_text(final_text)
        self._fallback_final_send = False
        if not continuation.strip():
            # Nothing new to send — the visible partial already matches final text.
            self._already_sent = True
            self._final_response_sent = True
            return

        raw_limit = getattr(self.adapter, "MAX_MESSAGE_LENGTH", 4096)
        safe_limit = max(500, raw_limit - 100)
        chunks = self._split_text_chunks(continuation, safe_limit)

        last_message_id: Optional[str] = None
        last_successful_chunk = ""
        sent_any_chunk = False
        for chunk in chunks:
            # Try sending with one retry on flood-control errors.
            result = None
            for attempt in range(2):
                result = await self.adapter.send(
                    chat_id=self.chat_id,
                    content=chunk,
                    metadata=self.metadata,
                )
                if result.success:
                    break
                if attempt == 0 and self._is_flood_error(result):
                    logger.debug(
                        "Flood control on fallback send, retrying in 3s"
                    )
                    await asyncio.sleep(3.0)
                else:
                    break  # non-flood error or second attempt failed

            if not result or not result.success:
                if sent_any_chunk:
                    # Some continuation text already reached the user. Suppress
                    # the base gateway final-send path so we don't resend the
                    # full response and create another duplicate.
                    self._already_sent = True
                    self._final_response_sent = True
                    self._message_id = last_message_id
                    self._last_sent_text = last_successful_chunk
                    self._fallback_prefix = ""
                    return
                # No fallback chunk reached the user — allow the normal gateway
                # final-send path to try one more time.
                self._already_sent = False
                self._message_id = None
                self._last_sent_text = ""
                self._fallback_prefix = ""
                return
            sent_any_chunk = True
            last_successful_chunk = chunk
            last_message_id = result.message_id or last_message_id

        self._message_id = last_message_id
        self._already_sent = True
        self._final_response_sent = True
        self._last_sent_text = chunks[-1]
        self._fallback_prefix = ""

    def _is_flood_error(self, result) -> bool:
        """Check if a SendResult failure is due to flood control / rate limiting."""
        err = getattr(result, "error", "") or ""
        err_lower = err.lower()
        return "flood" in err_lower or "retry after" in err_lower or "rate" in err_lower

    async def _try_strip_cursor(self) -> None:
        """Best-effort edit to remove the cursor from the last visible message.

        Called when entering fallback mode so the user doesn't see a stuck
        cursor (▉) in the partial message.
        """
        if not self._message_id or self._message_id == "__no_edit__":
            return
        prefix = self._visible_prefix()
        if not prefix or not prefix.strip():
            return
        try:
            await self.adapter.edit_message(
                chat_id=self.chat_id,
                message_id=self._message_id,
                content=prefix,
            )
            self._last_sent_text = prefix
        except Exception:
            pass  # best-effort — don't let this block the fallback path

    async def _send_commentary(self, text: str) -> bool:
        """Send a completed interim assistant commentary message."""
        text = self._clean_for_display(text)
        if not text.strip():
            return False
        try:
            result = await self.adapter.send(
                chat_id=self.chat_id,
                content=text,
                metadata=self.metadata,
            )
            if result.success:
                self._already_sent = True
                return True
        except Exception as e:
            logger.error("Commentary send error: %s", e)
        return False

    async def _send_or_edit(self, text: str) -> bool:
        """Send or edit the streaming message.

        Returns True if the text was successfully delivered (sent or edited),
        False otherwise.  Callers like the overflow split loop use this to
        decide whether to advance past the delivered chunk.
        """
        # Strip MEDIA: directives so they don't appear as visible text.
        # Media files are delivered as native attachments after the stream
        # finishes (via _deliver_media_from_response in gateway/run.py).
        text = self._clean_for_display(text)
        if not text.strip():
            return True  # nothing to send is "success"
        try:
            if self._message_id is not None:
                if self._edit_supported:
                    # Skip if text is identical to what we last sent
                    if text == self._last_sent_text:
                        return True
                    # Edit existing message
                    result = await self.adapter.edit_message(
                        chat_id=self.chat_id,
                        message_id=self._message_id,
                        content=text,
                    )
                    if result.success:
                        self._already_sent = True
                        self._last_sent_text = text
                        # Successful edit — reset flood strike counter
                        self._flood_strikes = 0
                        return True
                    else:
                        # Edit failed.  If this looks like flood control / rate
                        # limiting, use adaptive backoff: double the edit interval
                        # and retry on the next cycle.  Only permanently disable
                        # edits after _MAX_FLOOD_STRIKES consecutive failures.
                        if self._is_flood_error(result):
                            self._flood_strikes += 1
                            self._current_edit_interval = min(
                                self._current_edit_interval * 2, 10.0,
                            )
                            logger.debug(
                                "Flood control on edit (strike %d/%d), "
                                "backoff interval → %.1fs",
                                self._flood_strikes,
                                self._MAX_FLOOD_STRIKES,
                                self._current_edit_interval,
                            )
                            if self._flood_strikes < self._MAX_FLOOD_STRIKES:
                                # Don't disable edits yet — just slow down.
                                # Update _last_edit_time so the next edit
                                # respects the new interval.
                                self._last_edit_time = time.monotonic()
                                return False

                        # Non-flood error OR flood strikes exhausted: enter
                        # fallback mode — send only the missing tail once the
                        # final response is available.
                        logger.debug(
                            "Edit failed (strikes=%d), entering fallback mode",
                            self._flood_strikes,
                        )
                        self._fallback_prefix = self._visible_prefix()
                        self._fallback_final_send = True
                        self._edit_supported = False
                        self._already_sent = True
                        # Best-effort: strip the cursor from the last visible
                        # message so the user doesn't see a stuck ▉.
                        await self._try_strip_cursor()
                        return False
                else:
                    # Editing not supported — skip intermediate updates.
                    # The final response will be sent by the fallback path.
                    return False
            else:
                # First message — send new
                result = await self.adapter.send(
                    chat_id=self.chat_id,
                    content=text,
                    metadata=self.metadata,
                )
                if result.success:
                    if result.message_id:
                        self._message_id = result.message_id
                    else:
                        self._edit_supported = False
                    self._already_sent = True
                    self._last_sent_text = text
                    if not result.message_id:
                        self._fallback_prefix = self._visible_prefix()
                        self._fallback_final_send = True
                        # Sentinel prevents re-entering the first-send path on
                        # every delta/tool boundary when platforms accept a
                        # message but do not return an editable message id.
                        self._message_id = "__no_edit__"
                    return True
                else:
                    # Initial send failed — disable streaming for this session
                    self._edit_supported = False
                    return False
        except Exception as e:
            logger.error("Stream send/edit error: %s", e)
            return False