bambuddy/backend/app/services/printer_manager.py

import asyncio
import logging
import re
import traceback
from collections.abc import Callable

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from backend.app.models.printer import Printer
from backend.app.services.bambu_mqtt import BambuMQTTClient, MQTTLogEntry, PrinterState, get_stage_name

logger = logging.getLogger(__name__)

# Models that have a real chamber temperature sensor
# Based on Home Assistant Bambu Lab integration
# P1P/P1S and A1/A1Mini do NOT have chamber temp sensors
# Includes both display names and internal codes from MQTT/SSDP
CHAMBER_TEMP_SUPPORTED_MODELS = frozenset(
    [
        # Display names
        "X1",
        "X1C",
        "X1E",  # X1 series
        "X2D",  # X2 series
        "P2S",  # P2 series
        "H2C",
        "H2D",
        "H2DPRO",
        "H2S",  # H2 series
        # Internal codes (from MQTT/SSDP)
        "BL-P001",  # X1/X1C
        "C13",  # X1E
        "N6",  # X2D
        "O1D",  # H2D
        "O1C",  # H2C
        "O1C2",  # H2C (dual nozzle variant)
        "O1S",  # H2S
        "O1E",  # H2D Pro
        "O2D",  # H2D Pro (alternate code)
        "N7",  # P2S
    ]
)

# Models that may incorrectly report stg_cur=0 when idle (firmware bug)
# Based on Home Assistant Bambu Lab integration observations
# See: https://github.com/greghesp/ha-bambulab/blob/main/custom_components/bambu_lab/pybambu/models.py
A1_MODELS = frozenset(
    [
        # Display names
        "A1",
        "A1 MINI",
        "A1-MINI",
        "A1MINI",
        # Internal codes (from MQTT/SSDP)
        "N1",  # A1 Mini
        "N2S",  # A1
    ]
)

# Models affected by the stg_cur=0 idle bug (firmware reports stg_cur=0 when idle,
# which maps to "Printing" in STAGE_NAMES and overrides the correct IDLE state)
STG_CUR_IDLE_BUG_MODELS = A1_MODELS | frozenset(
    [
        # Display names
        "P1P",
        "P1S",
        # Internal codes (from MQTT/SSDP)
        "C11",  # P1P
        "C12",  # P1S
    ]
)


def supports_chamber_temp(model: str | None) -> bool:
    """Check if a printer model has a real chamber temperature sensor.

    P1P, P1S, A1, and A1Mini do NOT have chamber temp sensors.
    The 'chamber_temper' value they report is meaningless.
    """
    if not model:
        return False
    # Normalize model name (uppercase, strip whitespace)
    model_upper = model.strip().upper()
    return model_upper in CHAMBER_TEMP_SUPPORTED_MODELS


# Models with an ACTIVE chamber heater (M141 has an effect).
# Many printers in CHAMBER_TEMP_SUPPORTED_MODELS only have a passive sensor —
# X1C, X1E, P2S report chamber temperature but cannot actively heat it. Only
# the models below ship a PTC heater that responds to M141.
CHAMBER_HEATER_MODELS = frozenset(
    [
        # Display names
        "H2C",
        "H2D",
        "H2DPRO",
        "H2S",
        "X2D",
        # Internal codes (from MQTT/SSDP)
        "O1C",  # H2C
        "O1C2",  # H2C dual-nozzle variant
        "O1D",  # H2D
        "O1E",  # H2D Pro
        "O2D",  # H2D Pro alternate code
        "O1S",  # H2S
        "N6",  # X2D
    ]
)


def supports_chamber_heater(model: str | None) -> bool:
    """Check if a printer model has an active chamber heater (responds to M141).

    The chamber temperature SENSOR is more widely deployed than the chamber
    HEATER — X1C/X1E/P2S report chamber temp but ignore M141. Only H2C, H2D,
    H2D Pro, H2S, X2D actually heat. Sensor-only models silently swallow the
    command at the firmware level, so we 400 at the route to surface that.
    """
    if not model:
        return False
    return model.strip().upper() in CHAMBER_HEATER_MODELS


# Models with a cooling / heating airduct flap. Same set as the frontend
# PrintersPage airduct-toggle whitelist (P2S, X2D, H2D, H2C, H2S, H2D Pro).
# X1E has a chamber heater but NO airduct flap — the warm-air recirculation
# happens via the fixed front-door inlet, so no `set_airduct` command is
# needed (and the firmware ignores it). P2S has an airduct but no heater —
# the flap manages chamber airflow even without an active heater. The
# intersection (chamber heater AND airduct) is what the preheat stage cares
# about: when M141 fires we also need to assert heating mode, otherwise the
# default cooling mode actively fights the chamber heater.
CHAMBER_AIRDUCT_MODELS = frozenset(
    [
        # Display names
        "P2S",
        "X2D",
        "H2C",
        "H2D",
        "H2DPRO",
        "H2S",
        # Internal codes (from MQTT/SSDP)
        "N7",  # P2S
        "N6",  # X2D
        "O1C",  # H2C
        "O1C2",  # H2C dual-nozzle variant
        "O1D",  # H2D
        "O1E",  # H2D Pro
        "O2D",  # H2D Pro alternate code
        "O1S",  # H2S
    ]
)


def supports_airduct(model: str | None) -> bool:
    """Check if a printer model has a cooling / heating airduct mode toggle.

    Mirrors the frontend PrintersPage `['P2S', 'X2D', 'H2D', 'H2C', 'H2S']`
    + H2D Pro whitelist. Distinct from `supports_chamber_heater` — P2S has
    the airduct toggle but no active heater, and X1E has the heater but no
    airduct. The preheat stage cares about the intersection (heater AND
    airduct) so it can flip the flap to heating before energising M141.
    """
    if not model:
        return False
    return model.strip().upper() in CHAMBER_AIRDUCT_MODELS


def has_stg_cur_idle_bug(model: str | None) -> bool:
    """Check if a printer model may incorrectly report stg_cur=0 when idle.

    Some firmware versions report stg_cur=0 (which maps to "Printing")
    even when the printer is idle. Originally observed on A1/A1 Mini via the
    Home Assistant Bambu Lab integration, also confirmed on P1S.
    """
    if not model:
        return False
    model_upper = model.strip().upper()
    return model_upper in STG_CUR_IDLE_BUG_MODELS


def is_bed_slinger(model: str | None) -> bool:
    """Whether the printer's Z axis controls the *toolhead*, not the bed.

    Bambu's A1 family (A1, A1 Mini; internal codes N1 / N2S) are open-frame
    bed-slingers: the bed moves on Y, the toolhead moves on X+Z. On every
    other current model (X1, P1, H2, H2C, H2D, H2S, P2S, ...) the bed moves
    on Z and the toolhead is fixed in Z.

    G-code direction is opposite on these two families. `G1 Z-10` reduces
    the nozzle-bed gap on both, but on bed-on-Z machines it does so by
    moving the BED up, while on bed-slingers it does so by moving the
    TOOLHEAD down — which is what crashed the nozzle in #1334.
    """
    if not model:
        return False
    return model.strip().upper() in A1_MODELS


# Minimum firmware versions for AMS drying support (confirmed via capture testing)
# Keys are exact model names (upper-cased). Do NOT use substring matching — it would
# incorrectly gate X1E (matched by "X1") and H2D Pro (matched by "H2D").
_DRYING_MIN_FIRMWARE: dict[str, str] = {
    "H2D": "01.02.30.00",
    "H2S": "01.02.00.00",
    "H2C": "01.02.00.00",
    "O1C": "01.02.00.00",  # H2C SSDP model code
    "O1C2": "01.02.00.00",  # H2C dual-nozzle SSDP model code
    "X1": "01.09.00.00",
    "X1C": "01.09.00.00",
    "P2S": "01.02.00.00",
    "N7": "01.02.00.00",  # P2S internal model code
}
# Models that definitely don't support AMS drying (no AMS 2 Pro / AMS-HT compatibility)
_DRYING_UNSUPPORTED_MODELS = frozenset({"A1", "A1MINI", "A1-MINI", "A1 MINI", "O1S", "N1", "N2S"})

# Models whose AMS can dry, but only from the printer's own touchscreen. Bambu's P1
# manual is explicit: "P1S connected AMS drying functions may only be controlled from
# the P1S screen." The firmware still answers `ams_filament_drying` with
# result: success and then does nothing — the reporter of #2533 sent it three times
# on an idle P1S with an AMS 2 Pro and the unit never left dry_status 0. Bambuddy
# originally listed P1P/P1S here as fw-gated (01.08+, #292); that version is when P1
# firmware gained AMS 2 Pro *support*, not remote drying, and it was never verified
# against a live P1. Nothing we can send will start a cycle, so we don't offer to.
_DRYING_SCREEN_ONLY_MODELS = frozenset({"P1P", "P1S"})


def drying_screen_only(model: str | None) -> bool:
    """True when the model's AMS dries only via the printer's own screen (#2533).

    Distinct from "unsupported": these printers *can* dry, and Bambuddy still shows
    a cycle started on the printer. They just can't be commanded to start or stop
    one remotely, so the UI explains that instead of silently dropping the control.
    """
    if not model:
        return False
    return model.strip().upper() in _DRYING_SCREEN_ONLY_MODELS


def supports_drying(model: str | None, firmware: str | None) -> bool:
    """Check if a printer model accepts remote AMS drying commands.

    Known models with confirmed min firmware get version-gated.
    Known unsupported models, and models that only dry from their own screen,
    are blocked.
    All other models (H2D Pro, X1E, future models) are allowed —
    the command fails gracefully with result: "fail" if unsupported.
    """
    if not model:
        return False
    model_upper = model.strip().upper()
    if model_upper in _DRYING_UNSUPPORTED_MODELS or model_upper in _DRYING_SCREEN_ONLY_MODELS:
        return False
    if model_upper in _DRYING_MIN_FIRMWARE:
        return bool(firmware and firmware >= _DRYING_MIN_FIRMWARE[model_upper])
    # For all other models: allow
    return True


# Minimum firmware versions for AMS "Print While Drying" — drying that runs CONCURRENTLY
# with an active print. Strictly stricter than _DRYING_MIN_FIRMWARE (idle drying). Verified
# against Bambu wiki release notes — the canonical phrasing on every supported model is
# "printing while filament is drying" / "Print While Drying". Models absent from the wiki
# release notes (A1, A1 Mini, P1*, X1 non-C, X1E) are intentionally excluded — the firmware
# will reject the command in those cases anyway via dry_sf_reason=[0] (TaskOccupied).
_DRY_WHILE_PRINTING_MIN_FIRMWARE: dict[str, str] = {
    "H2D": "01.03.00.00",
    "H2D PRO": "01.02.00.00",
    "H2DPRO": "01.02.00.00",
    "O1E": "01.02.00.00",  # H2D Pro SSDP code
    "O2D": "01.02.00.00",  # H2D Pro alternate code
    "H2C": "01.02.00.00",
    "O1C": "01.02.00.00",  # H2C SSDP code
    "O1C2": "01.02.00.00",  # H2C dual-nozzle SSDP code
    "H2S": "01.02.00.00",
    "X2D": "01.01.00.00",
    "N6": "01.01.00.00",  # X2D internal code
    "X1C": "01.11.02.00",
    "BL-P001": "01.11.02.00",  # X1C internal code
    "P2S": "01.02.00.00",
    "N7": "01.02.00.00",  # P2S internal code
    "A2L": "01.01.00.00",
    "N9": "01.01.00.00",  # A2L internal code
}


def supports_drying_while_printing(model: str | None, firmware: str | None) -> bool:
    """Check if a printer model+firmware supports running AMS drying CONCURRENTLY
    with an active print.

    Distinct from supports_drying() — that gates idle drying. This gate is strict:
    only models explicitly confirmed by Bambu wiki release notes are allowed.
    On unsupported models the firmware returns dry_sf_reason=[0] (TaskOccupied)
    while a print is running, so being conservative here costs nothing — the
    firmware is the ultimate arbiter, this gate just hides UI affordances.
    """
    if not model:
        return False
    model_upper = model.strip().upper()
    if model_upper not in _DRY_WHILE_PRINTING_MIN_FIRMWARE:
        return False
    return bool(firmware and firmware >= _DRY_WHILE_PRINTING_MIN_FIRMWARE[model_upper])


class PrinterInfo:
    """Basic printer info for callbacks."""

    def __init__(self, name: str, serial_number: str):
        self.name = name
        self.serial_number = serial_number


class PrinterManager:
    """Manager for multiple printer connections."""

    def __init__(self):
        self._clients: dict[int, BambuMQTTClient] = {}
        self._models: dict[int, str | None] = {}  # Cache printer models for feature detection
        self._printer_info: dict[int, PrinterInfo] = {}  # Cache printer name/serial for callbacks
        self._on_print_start: Callable[[int, dict], None] | None = None
        self._on_print_complete: Callable[[int, dict], None] | None = None
        self._on_print_running_observed: Callable[[int, dict], None] | None = None
        self._on_finish_photo_moment: Callable[[int, dict], None] | None = None
        self._on_status_change: Callable[[int, PrinterState], None] | None = None
        self._on_ams_change: Callable[[int, list], None] | None = None
        self._on_layer_change: Callable[[int, int], None] | None = None
        self._on_bed_temp_update: Callable[[int, float], None] | None = None
        self._on_drying_complete: Callable[[int, int], None] | None = None
        self._loop: asyncio.AbstractEventLoop | None = None
        # Track who started the current print (Issue #206)
        self._current_print_user: dict[int, dict] = {}  # {printer_id: {"user_id": int, "username": str}}
        # Track printers awaiting plate-clear acknowledgment after a finished/failed print.
        # Persisted to DB (printers.awaiting_plate_clear) so the gate survives restarts/power
        # cycles — see issue #961. Loaded into this set at startup via load_awaiting_plate_clear_from_db().
        self._awaiting_plate_clear: set[int] = set()

    def get_printer(self, printer_id: int) -> PrinterInfo | None:
        """Get printer info by ID."""
        return self._printer_info.get(printer_id)

    def set_current_print_user(self, printer_id: int, user_id: int, username: str):
        """Track who started the current print (Issue #206)."""
        self._current_print_user[printer_id] = {"user_id": user_id, "username": username}

    def get_current_print_user(self, printer_id: int) -> dict | None:
        """Get the user who started the current print (Issue #206)."""
        return self._current_print_user.get(printer_id)

    def clear_current_print_user(self, printer_id: int):
        """Clear the current print user when print completes (Issue #206)."""
        self._current_print_user.pop(printer_id, None)

    def is_awaiting_plate_clear(self, printer_id: int) -> bool:
        """Return True when the printer finished/failed a print and is waiting for the
        user to acknowledge the plate is cleared before the queue may dispatch the next job.
        """
        return printer_id in self._awaiting_plate_clear

    def set_awaiting_plate_clear(self, printer_id: int, awaiting: bool):
        """Set/clear the awaiting-plate-clear gate and persist it to DB.

        Persisted so the gate survives Bambuddy/printer restarts (#961): after Auto Off
        cycles the printer, the printer boots into IDLE with no memory of the previous
        finish, and without persistence the queue would bypass the confirmation prompt.

        Also broadcasts an updated ``printer_status`` over the WebSocket (#1128).
        ``awaiting_plate_clear`` is a Bambuddy-side flag — toggling it does not
        produce an MQTT push from the printer, so without an explicit broadcast
        any UI subscriber that's NOT the originating tab would stay stale until
        the next coincidental status refresh. The plate-clear button on the
        printer card disappeared "immediately" only because of an optimistic
        React Query cache update on the click path; clearing the flag through
        any other route (an admin script, a second tab, an automation that
        hits ``POST /printers/{id}/clear-plate`` directly) silently broke the
        UI without it. Centralised here so every current AND future caller is
        covered without each one having to remember to broadcast.
        """
        if awaiting:
            self._awaiting_plate_clear.add(printer_id)
        else:
            self._awaiting_plate_clear.discard(printer_id)
        # Only create the coroutine when there is a loop to run it on — otherwise Python
        # emits "coroutine was never awaited" warnings (e.g. in sync unit tests).
        if self._loop and self._loop.is_running():
            self._schedule_async(self._persist_awaiting_plate_clear(printer_id, awaiting))
            self._schedule_async(self._broadcast_status_change(printer_id))

    async def _broadcast_status_change(self, printer_id: int) -> None:
        """Emit a ``printer_status`` WebSocket update for this printer (#1128).

        Used for state changes that don't come from MQTT — currently just the
        ``awaiting_plate_clear`` flag, but any future Bambuddy-side flag added
        to ``printer_state_to_dict`` should plumb through here too. The
        existing MQTT-driven broadcast in ``main.on_printer_status_change``
        deduplicates on a status_key that intentionally excludes Bambuddy
        flags (so e.g. queue-state changes don't get echoed as printer
        events), which is precisely why those flags need their own emit.

        Lazy-imports ``ws_manager`` to keep ``printer_manager`` clean of
        application-layer infra at module-import time — the broadcast is the
        only thing here that needs it.
        """
        state = self.get_status(printer_id)
        if not state:
            # Printer disconnected or unknown — nothing to broadcast. The
            # next reconnect will produce a fresh status push anyway, so the
            # UI eventually catches up without us forcing a stale snapshot
            # on subscribers now.
            return
        try:
            from backend.app.core.websocket import ws_manager

            await ws_manager.send_printer_status(
                printer_id,
                printer_state_to_dict(
                    state,
                    printer_id,
                    self.get_model(printer_id),
                    self.get_drying_targets(printer_id),
                ),
            )
        except Exception as e:
            logger.warning(
                "Failed to broadcast printer_status after Bambuddy-side state change for printer %d: %s",
                printer_id,
                e,
            )

    async def _persist_awaiting_plate_clear(self, printer_id: int, awaiting: bool):
        from backend.app.core.database import run_with_retry

        async def _do(db):
            printer = await db.get(Printer, printer_id)
            if printer is not None:
                printer.awaiting_plate_clear = awaiting
                await db.commit()

        try:
            await run_with_retry(_do, label=f"persist awaiting_plate_clear printer={printer_id}")
        except Exception as e:
            logger.warning("Failed to persist awaiting_plate_clear for printer %d: %s", printer_id, e)

    async def load_awaiting_plate_clear_from_db(self):
        """Rehydrate the awaiting-plate-clear set from the printers table on startup."""
        from backend.app.core.database import async_session

        try:
            async with async_session() as db:
                result = await db.execute(select(Printer.id).where(Printer.awaiting_plate_clear.is_(True)))
                ids = {row[0] for row in result.all()}
                self._awaiting_plate_clear = ids
                if ids:
                    logger.info("Loaded %d printer(s) awaiting plate-clear acknowledgment: %s", len(ids), sorted(ids))
        except Exception as e:
            logger.warning("Failed to load awaiting_plate_clear from DB: %s", e)

    def set_event_loop(self, loop: asyncio.AbstractEventLoop):
        """Set the event loop for async callbacks."""
        self._loop = loop

    def set_print_start_callback(self, callback: Callable[[int, dict], None]):
        """Set callback for print start events."""
        self._on_print_start = callback

    def set_print_complete_callback(self, callback: Callable[[int, dict], None]):
        """Set callback for print completion events."""
        self._on_print_complete = callback

    def set_print_running_observed_callback(self, callback: Callable[[int, dict], None]):
        """Set callback for restart-recovery RUNNING-state observations (#1485
        follow-up). Fires the first time we see ``state == RUNNING`` for a
        printer that started its print before Bambuddy came up — the #1304
        guard suppresses ``on_print_start`` for these, so anything that
        normally hangs off it (e.g. timelapse baseline capture) needs this
        hook to recover."""
        self._on_print_running_observed = callback

    def set_finish_photo_moment_callback(self, callback: Callable[[int, dict], None]):
        """Set callback for the #1721 finish-photo moment.

        Fires on the stage-22 (\"Filament unloading\") edge at end-of-print
        — the framing window where the toolhead is parked but the bed
        hasn't dropped yet. Falls back to firing at the FINISH-state
        transition for prints that skip stage 22 (cancel, external-spool-
        only, HMS halt, firmware variants). Payload includes the
        ``trigger`` key (``\"stage_22\"`` or ``\"finish_state\"``) and
        ``timelapse_was_active`` so the photo path can choose between
        live-camera capture and timelapse last-frame extraction."""
        self._on_finish_photo_moment = callback

    def set_status_change_callback(self, callback: Callable[[int, PrinterState], None]):
        """Set callback for status change events."""
        self._on_status_change = callback

    def set_ams_change_callback(self, callback: Callable[[int, list], None]):
        """Set callback for AMS data change events."""
        self._on_ams_change = callback

    def set_layer_change_callback(self, callback: Callable[[int, int], None]):
        """Set callback for layer change events. Receives (printer_id, layer_num)."""
        self._on_layer_change = callback

    def set_bed_temp_update_callback(self, callback: Callable[[int, float], None]):
        """Set callback for bed temperature updates. Receives (printer_id, bed_temp)."""
        self._on_bed_temp_update = callback

    def set_drying_complete_callback(self, callback: Callable[[int, int], None]):
        """Set callback for AMS drying completion events (#1349).

        Receives ``(printer_id, ams_id)``. Fires once per falling edge of
        ``dry_time`` (>0 → 0) for each AMS unit.
        """
        self._on_drying_complete = callback

    def _schedule_async(self, coro):
        """Schedule an async coroutine from a sync context.

        Captures exceptions from the coroutine and logs them to prevent
        silent failures in callbacks.
        """
        if self._loop and self._loop.is_running():
            future = asyncio.run_coroutine_threadsafe(coro, self._loop)

            def handle_exception(f):
                try:
                    # This will re-raise any exception from the coroutine
                    f.result()
                except Exception as e:
                    import logging

                    logging.getLogger(__name__).error(f"Exception in scheduled callback: {e}", exc_info=True)

            future.add_done_callback(handle_exception)

    async def connect_printer(self, printer: Printer) -> bool:
        """Connect to a printer."""
        if printer.id in self._clients:
            self.disconnect_printer(printer.id)

        printer_id = printer.id

        def on_state_change(state: PrinterState):
            if self._on_status_change:
                self._schedule_async(self._on_status_change(printer_id, state))

        def on_print_start(data: dict):
            if self._on_print_start:
                self._schedule_async(self._on_print_start(printer_id, data))

        def on_print_complete(data: dict):
            if self._on_print_complete:
                self._schedule_async(self._on_print_complete(printer_id, data))

        def on_print_running_observed(data: dict):
            if self._on_print_running_observed:
                self._schedule_async(self._on_print_running_observed(printer_id, data))

        def on_finish_photo_moment(data: dict):
            if self._on_finish_photo_moment:
                self._schedule_async(self._on_finish_photo_moment(printer_id, data))

        def on_ams_change(ams_data: list):
            if self._on_ams_change:
                self._schedule_async(self._on_ams_change(printer_id, ams_data))

        def on_layer_change(layer_num: int):
            if self._on_layer_change:
                self._schedule_async(self._on_layer_change(printer_id, layer_num))

        def on_bed_temp_update(bed_temp: float):
            if self._on_bed_temp_update:
                self._schedule_async(self._on_bed_temp_update(printer_id, bed_temp))

        def on_drying_complete(ams_id: int):
            if self._on_drying_complete:
                self._schedule_async(self._on_drying_complete(printer_id, ams_id))

        client = BambuMQTTClient(
            ip_address=printer.ip_address,
            serial_number=printer.serial_number,
            access_code=printer.access_code,
            model=printer.model,
            on_state_change=on_state_change,
            on_print_start=on_print_start,
            on_print_complete=on_print_complete,
            on_ams_change=on_ams_change,
            on_layer_change=on_layer_change,
            on_bed_temp_update=on_bed_temp_update,
            on_drying_complete=on_drying_complete,
            on_print_running_observed=on_print_running_observed,
            on_finish_photo_moment=on_finish_photo_moment,
        )

        client.connect()
        self._clients[printer_id] = client
        self._models[printer_id] = printer.model  # Cache model for feature detection
        self._printer_info[printer_id] = PrinterInfo(printer.name, printer.serial_number)

        # Wait a moment for connection
        await asyncio.sleep(1)
        return client.state.connected

    def disconnect_printer(self, printer_id: int, timeout: float = 0):
        """Disconnect from a printer."""
        if printer_id in self._clients:
            self._clients[printer_id].disconnect(timeout=timeout)
            del self._clients[printer_id]
        self._models.pop(printer_id, None)  # Clean up model cache
        self._printer_info.pop(printer_id, None)  # Clean up printer info cache

    def disconnect_all(self, timeout: float = 0):
        """Disconnect from all printers."""
        for printer_id in list(self._clients.keys()):
            self.disconnect_printer(printer_id, timeout=timeout)

    def get_status(self, printer_id: int) -> PrinterState | None:
        """Get the current status of a printer (checks for stale connections)."""
        if printer_id in self._clients:
            client = self._clients[printer_id]
            # Check staleness and update connected state if needed
            client.check_staleness()
            return client.state
        return None

    # Gcode states in which a job is loaded / in progress and cutting power
    # would ruin the print. PAUSE is included on purpose — a paused print is
    # still loaded on the bed. Used by the smart-plug auto-off guard (#1890) so
    # a re-print started from the touchscreen isn't killed mid-print.
    ACTIVE_PRINT_STATES = ("RUNNING", "PAUSE", "PREPARE", "SLICING")

    def is_print_active(self, printer_id: int) -> bool:
        """True when the printer currently has a print loaded / in progress.

        Returns False when disconnected or in any idle/terminal state
        (IDLE / FINISH / FAILED / unknown), so callers fail *open* only for
        the safe "nothing is printing" case. #1890.
        """
        state = self.get_status(printer_id)
        if not state or not state.connected:
            return False
        return state.state in self.ACTIVE_PRINT_STATES

    def get_model(self, printer_id: int) -> str | None:
        """Get the cached model for a printer."""
        return self._models.get(printer_id)

    def get_drying_targets(self, printer_id: int) -> dict[int, dict] | None:
        """Get cached active drying target params keyed by AMS id.

        Returned dict shape: ``{ams_id: {"filament": str, "temp": int}}``.
        Returns ``None`` when the printer is not connected. The cache is
        seeded by ``send_drying_command(mode=1)`` and cleared when drying
        stops or on the ``dry_time`` falling edge (handled inside
        ``BambuMQTTClient``).
        """
        client = self._clients.get(printer_id)
        return client._drying_targets if client else None

    def get_all_statuses(self) -> dict[int, PrinterState]:
        """Get status of all connected printers (checks for stale connections)."""
        result = {}
        for printer_id, client in self._clients.items():
            # Check staleness and update connected state if needed
            client.check_staleness()
            result[printer_id] = client.state
        return result

    def is_connected(self, printer_id: int) -> bool:
        """Check if a printer is connected (checks for stale connections)."""
        if printer_id in self._clients:
            client = self._clients[printer_id]
            # Check staleness and update connected state if needed
            return client.check_staleness()
        return False

    def get_client(self, printer_id: int) -> BambuMQTTClient | None:
        """Get the MQTT client for a printer."""
        return self._clients.get(printer_id)

    def mark_printer_offline(self, printer_id: int):
        """Mark a printer as offline and trigger status callback.

        This is used when we know the printer power was cut (e.g., smart plug turned off)
        to immediately update the UI without waiting for MQTT timeout.
        """
        import logging

        logger = logging.getLogger(__name__)

        if printer_id in self._clients:
            client = self._clients[printer_id]
            if client.state.connected:
                logger.info("Marking printer %s as offline (smart plug power off)", printer_id)
                client.state.connected = False
                client.state.state = "unknown"
                # Trigger the status change callback to broadcast via WebSocket
                if self._on_status_change:
                    self._schedule_async(self._on_status_change(printer_id, client.state))

    def start_print(
        self,
        printer_id: int,
        filename: str,
        plate_id: int = 1,
        ams_mapping: list[int] | None = None,
        bed_levelling: bool = True,
        flow_cali: bool = False,
        vibration_cali: bool = True,
        layer_inspect: bool = False,
        timelapse: bool = False,
        use_ams: bool = True,
        nozzle_offset_cali: bool = False,
        nozzle_mapping: str | None = None,
    ) -> bool:
        """Start a print on a connected printer.

        ``nozzle_mapping`` is an opaque JSON string captured from BambuStudio's
        project_file MQTT command (H2C rack-swap slicer pick preservation,
        #1780). It rides through to the MQTT client untouched; the dispatch
        builder there parses + injects it only on dual-nozzle models.
        """
        caller = traceback.extract_stack(limit=3)[0]
        logger.info(
            "PRINT COMMAND: printer=%s, file=%s, caller=%s:%s:%s",
            printer_id,
            filename,
            caller.filename.split("/")[-1],
            caller.lineno,
            caller.name,
        )
        if printer_id in self._clients:
            return self._clients[printer_id].start_print(
                filename,
                plate_id,
                ams_mapping=ams_mapping,
                timelapse=timelapse,
                bed_levelling=bed_levelling,
                flow_cali=flow_cali,
                vibration_cali=vibration_cali,
                layer_inspect=layer_inspect,
                use_ams=use_ams,
                nozzle_offset_cali=nozzle_offset_cali,
                nozzle_mapping=nozzle_mapping,
            )
        return False

    def stop_print(self, printer_id: int) -> bool:
        """Stop the current print on a connected printer."""
        if printer_id in self._clients:
            return self._clients[printer_id].stop_print()
        return False

    async def wait_for_cooldown(
        self,
        printer_id: int,
        target_temp: float = 50.0,
        timeout: int = 600,
        check_interval: int = 10,
    ) -> bool:
        """Wait for the nozzle to cool down to a safe temperature.

        Args:
            printer_id: The printer to monitor
            target_temp: Target temperature to wait for (default 50°C)
            timeout: Maximum seconds to wait (default 600s = 10 min)
            check_interval: Seconds between temperature checks (default 10s)

        Returns:
            True if cooled down, False if timeout or not connected
        """
        import logging

        logger = logging.getLogger(__name__)

        elapsed = 0
        while elapsed < timeout:
            state = self.get_status(printer_id)
            if not state or not state.connected:
                logger.warning("Printer %s disconnected during cooldown wait", printer_id)
                return False

            # Check nozzle temperature (and nozzle_2 for dual extruders)
            nozzle_temp = state.temperatures.get("nozzle", 0)
            nozzle_2_temp = state.temperatures.get("nozzle_2", 0)
            max_temp = max(nozzle_temp, nozzle_2_temp)

            if max_temp <= target_temp:
                logger.info("Printer %s cooled down to %s°C", printer_id, max_temp)
                return True

            logger.debug("Printer %s nozzle at %s°C, waiting for %s°C...", printer_id, max_temp, target_temp)
            await asyncio.sleep(check_interval)
            elapsed += check_interval

        logger.warning("Printer %s cooldown timeout after %ss", printer_id, timeout)
        return False

    def enable_logging(self, printer_id: int, enabled: bool = True) -> bool:
        """Enable or disable MQTT logging for a printer."""
        if printer_id in self._clients:
            self._clients[printer_id].enable_logging(enabled)
            return True
        return False

    def get_logs(self, printer_id: int) -> list[MQTTLogEntry]:
        """Get MQTT logs for a printer."""
        if printer_id in self._clients:
            return self._clients[printer_id].get_logs()
        return []

    def clear_logs(self, printer_id: int) -> bool:
        """Clear MQTT logs for a printer."""
        if printer_id in self._clients:
            self._clients[printer_id].clear_logs()
            return True
        return False

    def is_logging_enabled(self, printer_id: int) -> bool:
        """Check if logging is enabled for a printer."""
        if printer_id in self._clients:
            return self._clients[printer_id].logging_enabled
        return False

    def send_drying_command(
        self,
        printer_id: int,
        ams_id: int,
        temp: int,
        duration: int,
        mode: int = 1,
        filament: str = "",
        rotate_tray: bool = False,
    ) -> bool:
        """Send AMS drying command to printer."""
        if printer_id not in self._clients:
            return False
        return self._clients[printer_id].send_drying_command(ams_id, temp, duration, mode, filament, rotate_tray)

    def request_status_update(self, printer_id: int) -> bool:
        """Request a full status update from the printer.

        This sends a 'pushall' command to get the latest data including nozzle info.
        """
        if printer_id in self._clients:
            return self._clients[printer_id].request_status_update()
        return False

    # Probe budget for test_connection (#1445). Was a fixed 2s sleep, which was
    # too short for P1S firmware whose broker / TLS handshake routinely takes
    # 3–5s to surface a CONNACK on a cold MQTT session. We now poll up to
    # PROBE_TIMEOUT_SECONDS and early-return the moment we see connected=True,
    # so happy-path connections still finish in ~1–2s and slow brokers get the
    # headroom they need instead of getting falsely rejected.
    PROBE_TIMEOUT_SECONDS = 8.0
    PROBE_POLL_INTERVAL_SECONDS = 0.2

    async def test_connection(
        self,
        ip_address: str,
        serial_number: str,
        access_code: str,
    ) -> dict:
        """Test connection to a printer without persisting.

        Polls for up to PROBE_TIMEOUT_SECONDS and tears the probe client down
        off-loop. The teardown matters: `client.disconnect()` ends in paho's
        `loop_stop()` which `join()`s the network thread — if the thread is
        still mid-TLS-handshake to a slow printer, that join blocks the
        asyncio event loop and every other HTTP request queues behind it. The
        original synchronous teardown produced the #1445 "Docker container
        hangs" symptom on P1S when called from POST /printers/.
        """
        client = BambuMQTTClient(
            ip_address=ip_address,
            serial_number=serial_number,
            access_code=access_code,
        )

        try:
            client.connect()
            deadline = asyncio.get_running_loop().time() + self.PROBE_TIMEOUT_SECONDS
            while not client.state.connected and asyncio.get_running_loop().time() < deadline:
                await asyncio.sleep(self.PROBE_POLL_INTERVAL_SECONDS)

            result = {
                "success": client.state.connected,
                "state": client.state.state if client.state.connected else None,
                "model": client.state.raw_data.get("device_model"),
            }
        finally:
            # Off-loop teardown — see docstring. paho's loop_stop() joins the
            # network thread which may still be in a slow TLS handshake.
            await asyncio.to_thread(client.disconnect)

        return result


def get_derived_status_name(state: PrinterState, model: str | None = None) -> str | None:
    """
    Compute a human-readable status name based on printer state.

    Uses stg_cur when available, otherwise derives status from temperature data
    when the printer is heating before a print starts.

    Args:
        state: The printer state to analyze
        model: Optional printer model for model-specific workarounds
    """
    # Firmware bug: some models (A1, P1P, P1S) report stg_cur=0 when not printing.
    # stg_cur=0 maps to "Printing" in STAGE_NAMES, which incorrectly overrides the
    # real state (IDLE, FINISH, FAILED, etc.). Only trust stg_cur when the printer
    # is actually in an active print state (RUNNING or PAUSE).
    if state.state not in ("RUNNING", "PAUSE") and state.stg_cur == 0 and has_stg_cur_idle_bug(model):
        return None

    # If we have a valid calibration stage, use it
    # X1 models use -1 for idle, A1/P1 models use 255 for idle
    # Valid stage numbers are 0-254
    if 0 <= state.stg_cur < 255:
        return get_stage_name(state.stg_cur)

    # If not in RUNNING state, no derived status needed
    if state.state != "RUNNING":
        return None

    # Check if we're in an early phase where temperatures are heating
    temps = state.temperatures or {}
    progress = state.progress or 0

    # Only derive heating status when progress is very low (< 2%)
    # This indicates we're in the preparation phase, not actually printing
    if progress >= 2:
        return None

    # Check bed temperature - if target is set and current is significantly below
    bed_temp = temps.get("bed", 0)
    bed_target = temps.get("bed_target", 0)

    # Check nozzle temperature
    nozzle_temp = temps.get("nozzle", 0)
    nozzle_target = temps.get("nozzle_target", 0)

    # Temperature thresholds: consider "heating" if more than 10°C below target
    TEMP_THRESHOLD = 10

    # Determine what's heating (prioritize bed since it takes longer)
    if bed_target > 30 and (bed_target - bed_temp) > TEMP_THRESHOLD:
        return "Heating heatbed"
    elif nozzle_target > 30 and (nozzle_target - nozzle_temp) > TEMP_THRESHOLD:
        return "Heating nozzle"

    # If targets are set but we're close to them, we might be in final prep
    if bed_target > 30 or nozzle_target > 30:
        if progress == 0 and state.layer_num == 0:
            return "Preparing"

    return None


_PLATE_ID_RE = re.compile(r"plate_(\d+)\.gcode")


def parse_plate_id(gcode_file: str | None) -> int | None:
    """Extract the 1-indexed plate number from a Bambu gcode_file path.

    Returns None when the path is missing or has no `plate_N.gcode` segment.
    Shared by the REST status route and the WebSocket push path so both agree
    on the value sent to the frontend (#881 follow-up).
    """
    if not gcode_file:
        return None
    match = _PLATE_ID_RE.search(gcode_file)
    return int(match.group(1)) if match else None


def resolve_plate_id(state) -> int | None:
    """Resolve the active plate number from a PrinterState.

    Some firmware versions (e.g. P1S 01.10.00.00, #1166) put only the .3mf
    filename in print.gcode_file, so parse_plate_id() returns None and the
    printer card falls back to plate 1 — wrong thumbnail. When Bambuddy
    dispatched the print itself we already know the right plate, so we prefer
    that over the gcode_file echo. The subtask check prevents stale values
    from a previous Bambuddy-dispatched print bleeding into a Studio-direct
    print on the same printer.
    """
    dispatched_plate = getattr(state, "dispatched_plate_id", None)
    dispatched_subtask = getattr(state, "dispatched_subtask", None)
    if (
        dispatched_plate is not None
        and dispatched_subtask is not None
        and state.subtask_name
        and dispatched_subtask == state.subtask_name
    ):
        return dispatched_plate
    return parse_plate_id(state.gcode_file)


def printer_state_to_dict(
    state: PrinterState,
    printer_id: int | None = None,
    model: str | None = None,
    drying_targets: dict[int, dict] | None = None,
) -> dict:
    """Convert PrinterState to a JSON-serializable dict.

    Args:
        state: The printer state to convert
        printer_id: Optional printer ID for generating cover URLs
        model: Optional printer model for filtering unsupported features
        drying_targets: Optional per-AMS active-cycle params
            (``{ams_id: {"filament": str, "temp": int}}``) sourced from the
            BambuMQTTClient cache so the badge can display "PETG @ 65°C".
    """
    # Parse AMS data from raw_data
    ams_units = []
    vt_tray = []
    raw_data = state.raw_data or {}

    # Build K-profile lookup map: cali_idx -> k_value
    kprofile_map: dict[int, float] = {}
    for kp in state.kprofiles or []:
        if kp.slot_id is not None and kp.k_value:
            try:
                kprofile_map[kp.slot_id] = float(kp.k_value)
            except (ValueError, TypeError):
                pass  # Skip K-profile entries with unparseable values

    if "ams" in raw_data and isinstance(raw_data["ams"], list):
        for ams_data in raw_data["ams"]:
            trays = []
            for tray in ams_data.get("tray", []):
                tag_uid = tray.get("tag_uid")
                if tag_uid in ("", "0000000000000000"):
                    tag_uid = None
                tray_uuid = tray.get("tray_uuid")
                if tray_uuid in ("", "00000000000000000000000000000000"):
                    tray_uuid = None

                # Get K value: first try tray's k field, then lookup from K-profiles
                k_value = tray.get("k")
                cali_idx = tray.get("cali_idx")
                if k_value is None and cali_idx is not None and cali_idx in kprofile_map:
                    k_value = kprofile_map[cali_idx]

                # P1S / A1 Mini physically-empty-slot signal (#1322 follow-up by
                # @RosdasHH): for a truly empty slot the firmware sends only
                # {"id": N} — no state, no tray_type, no anything else. Treat
                # that as the firmware's "no spool" indicator (state=9) so the
                # assign-spool path in inventory.py can short-circuit a MQTT
                # publish the firmware would silently drop anyway. The
                # post-"Reset Slot" A1 Mini BMCU case sends a populated payload
                # (state=3, tray_type="") — different shape, doesn't match this
                # guard, still attempts the MQTT push per the #1322 fix.
                state_val = tray.get("state")
                if state_val is None and len(tray) == 1 and "id" in tray:
                    state_val = 9

                trays.append(
                    {
                        "id": int(tray.get("id", 0)),
                        "tray_color": tray.get("tray_color"),
                        "tray_type": tray.get("tray_type"),
                        "tray_sub_brands": tray.get("tray_sub_brands"),
                        "tray_id_name": tray.get("tray_id_name"),
                        "tray_info_idx": tray.get("tray_info_idx"),
                        "remain": tray.get("remain", 0),
                        "k": k_value,
                        "cali_idx": cali_idx,
                        "tag_uid": tag_uid,
                        "tray_uuid": tray_uuid,
                        "nozzle_temp_min": tray.get("nozzle_temp_min"),
                        "nozzle_temp_max": tray.get("nozzle_temp_max"),
                        "drying_temp": tray.get("drying_temp"),
                        "drying_time": tray.get("drying_time"),
                        "state": state_val,
                    }
                )
            # Prefer humidity_raw (actual percentage) over humidity (index 1-5)
            humidity_raw = ams_data.get("humidity_raw")
            humidity_idx = ams_data.get("humidity")
            humidity_value = None

            if humidity_raw is not None:
                try:
                    humidity_value = int(humidity_raw)
                except (ValueError, TypeError):
                    pass  # Skip unparseable humidity; will try index fallback
            # Fall back to index if no raw value (index is 1-5, not percentage)
            if humidity_value is None and humidity_idx is not None:
                try:
                    humidity_value = int(humidity_idx)
                except (ValueError, TypeError):
                    pass  # Skip unparseable humidity index; humidity remains None

            # AMS-HT has 1 tray, regular AMS has 4 trays
            is_ams_ht = len(trays) == 1

            # Active-cycle filament + target temperature for the badge.
            # Bambu does not echo the cycle's chosen filament/temp on the
            # per-tick AMS push, so prefer the cached target from the last
            # ``send_drying_command``. When we have no record (drying
            # started in a previous backend lifetime, or the cache was
            # never seeded), fall back to the first loaded tray's
            # tray_type + RFID-recommended drying_temp — the same heuristic
            # the popover already uses to seed defaults.
            ams_id_int = int(ams_data.get("id", 0))
            target = (drying_targets or {}).get(ams_id_int)
            dry_target_temp: int | None = None
            dry_filament: str | None = None
            if target:
                temp_val = target.get("temp")
                fil_val = target.get("filament") or ""
                if temp_val is not None:
                    try:
                        dry_target_temp = int(temp_val)
                    except (TypeError, ValueError):
                        dry_target_temp = None
                if fil_val:
                    dry_filament = str(fil_val)
            if dry_target_temp is None or not dry_filament:
                for tray in trays:
                    if tray.get("tray_type"):
                        if not dry_filament:
                            dry_filament = str(tray["tray_type"])
                        if dry_target_temp is None and tray.get("drying_temp"):
                            try:
                                dry_target_temp = int(tray["drying_temp"])
                            except (TypeError, ValueError):
                                pass
                        break

            ams_units.append(
                {
                    "id": ams_id_int,
                    "humidity": humidity_value,
                    "temp": ams_data.get("temp"),
                    "is_ams_ht": is_ams_ht,
                    "tray": trays,
                    # Serial number: Bambu MQTT uses "sn" key on AMS unit objects
                    "serial_number": str(ams_data.get("sn") or ams_data.get("serial_number") or ""),
                    # Firmware version: populated by _handle_version_info from get_version
                    "sw_ver": str(ams_data.get("sw_ver") or ""),
                    # Drying: dry_time > 0 means drying is active (minutes remaining)
                    "dry_time": int(ams_data.get("dry_time") or 0),
                    # Drying status from info hex bits (0=Off, 1=Checking, 2=Drying, 3=Cooling, etc.)
                    "dry_status": int(ams_data.get("dry_status") or 0),
                    "dry_sub_status": int(ams_data.get("dry_sub_status") or 0),
                    # Cannot-dry reasons from firmware (e.g. 1=InsufficientPower, 8=NeedPluginPower)
                    "dry_sf_reason": list(ams_data.get("dry_sf_reason") or []),
                    # Active-cycle filament name + target temperature
                    "dry_target_temp": dry_target_temp,
                    "dry_filament": dry_filament,
                    # Module type: "ams", "n3f", "n3s" (from get_version)
                    "module_type": str(ams_data.get("module_type") or ""),
                }
            )

    # Parse virtual tray (external spool) — now a list
    if "vt_tray" in raw_data:
        vt_tray_raw = raw_data["vt_tray"]
        # Defensive: MQTT sends vt_tray as a dict; normalize to list
        if isinstance(vt_tray_raw, dict):
            vt_tray_raw = [vt_tray_raw]
        elif not isinstance(vt_tray_raw, list):
            vt_tray_raw = []
        for vt_data in vt_tray_raw:
            vt_tag_uid = vt_data.get("tag_uid")
            if vt_tag_uid in ("", "0000000000000000"):
                vt_tag_uid = None
            vt_tray_uuid = vt_data.get("tray_uuid")
            if vt_tray_uuid in ("", "00000000000000000000000000000000"):
                vt_tray_uuid = None

            # Get K value for vt_tray
            vt_k_value = vt_data.get("k")
            vt_cali_idx = vt_data.get("cali_idx")
            if vt_k_value is None and vt_cali_idx is not None and vt_cali_idx in kprofile_map:
                vt_k_value = kprofile_map[vt_cali_idx]

            tray_id = int(vt_data.get("id", 254))
            vt_tray.append(
                {
                    "id": tray_id,
                    "tray_color": vt_data.get("tray_color"),
                    "tray_type": vt_data.get("tray_type"),
                    "tray_sub_brands": vt_data.get("tray_sub_brands"),
                    "tray_id_name": vt_data.get("tray_id_name"),
                    "tray_info_idx": vt_data.get("tray_info_idx"),
                    "remain": vt_data.get("remain", 0),
                    "k": vt_k_value,
                    "cali_idx": vt_cali_idx,
                    "tag_uid": vt_tag_uid,
                    "tray_uuid": vt_tray_uuid,
                    "nozzle_temp_min": vt_data.get("nozzle_temp_min"),
                    "nozzle_temp_max": vt_data.get("nozzle_temp_max"),
                }
            )

    # Get ams_extruder_map from raw_data (populated by MQTT handler from AMS info field)
    ams_extruder_map = raw_data.get("ams_extruder_map", {})

    # Filter out chamber temp for models that don't have a real sensor
    # P1P, P1S, A1, A1Mini report meaningless chamber_temper values
    temperatures = state.temperatures
    if not supports_chamber_temp(model):
        temperatures = {
            k: v for k, v in temperatures.items() if k not in ("chamber", "chamber_target", "chamber_heating")
        }

    result = {
        "connected": state.connected,
        "state": state.state,
        "current_print": state.current_print,
        "subtask_name": state.subtask_name,
        "gcode_file": state.gcode_file,
        "progress": state.progress,
        "remaining_time": state.remaining_time,
        "layer_num": state.layer_num,
        "total_layers": state.total_layers,
        "temperatures": temperatures,
        "hms_errors": [
            {
                "code": e.code,
                "attr": e.attr,
                "module": e.module,
                "severity": e.severity,
                "actions": e.actions,
                "job_id": e.job_id,
                "full_code": e.full_code,
            }
            for e in (state.hms_errors or [])
        ],
        # AMS data for filament colors
        "ams": ams_units if ams_units else None,
        "vt_tray": vt_tray,
        # AMS status for filament change tracking
        "ams_status_main": state.ams_status_main,
        "ams_status_sub": state.ams_status_sub,
        "tray_now": state.tray_now,
        # Per-AMS extruder map: {ams_id: extruder_id} where 0=right, 1=left
        "ams_extruder_map": ams_extruder_map,
        # WiFi signal strength
        "wifi_signal": state.wifi_signal,
        "wired_network": state.wired_network,
        "door_open": state.door_open,
        # AMS Filament Backup state (auto-switch to second spool). Tri-state:
        # True / False / None. None = unknown or unsupported (A1 family). UI
        # uses this to drive the small status icon next to the AMS drying icon.
        "ams_filament_backup": state.ams_filament_backup,
        # Calibration stage tracking
        "stg_cur": state.stg_cur,
        "stg_cur_name": get_derived_status_name(state, model),
        # Printable objects count for skip objects feature
        "printable_objects_count": len(state.printable_objects),
        # Fan speeds (0-100 percentage, None if not available)
        "cooling_fan_speed": state.cooling_fan_speed,
        "big_fan1_speed": state.big_fan1_speed,
        "big_fan2_speed": state.big_fan2_speed,
        "heatbreak_fan_speed": state.heatbreak_fan_speed,
        # Chamber light state
        "chamber_light": state.chamber_light,
        # Active extruder for dual-nozzle printers (0=right, 1=left)
        "active_extruder": state.active_extruder,
        # Print speed mode (1=silent, 2=standard, 3=sport, 4=ludicrous)
        "speed_level": state.speed_level,
        # H2C nozzle rack (tool-changer dock positions)
        # Map raw MQTT field names (type/diameter) to schema names (nozzle_type/nozzle_diameter)
        "nozzle_rack": [
            {
                "id": n.get("id", 0),
                "nozzle_type": n.get("type", ""),
                "nozzle_diameter": n.get("diameter", ""),
                "wear": n.get("wear"),
                "stat": n.get("stat"),
                "max_temp": n.get("max_temp", 0),
                "serial_number": n.get("serial_number", ""),
                "filament_color": n.get("filament_color", ""),
                "filament_id": n.get("filament_id", ""),
            }
            for n in (state.nozzle_rack or [])
        ],
        # AMS drying support
        "supports_drying": supports_drying(model, state.firmware_version),
        "supports_drying_while_printing": supports_drying_while_printing(model, state.firmware_version),
        "drying_screen_only": drying_screen_only(model),
        # 1-indexed plate number parsed from gcode_file (e.g. /Metadata/plate_2.gcode).
        # Pushed via WebSocket so the printer card picks up plate transitions within
        # a multi-plate 3MF without waiting for the 30 s REST poll (#881 follow-up).
        # current_archive_id is intentionally REST-only — it's stable for the life
        # of a print and needs a DB lookup the WebSocket path shouldn't pay for.
        "current_plate_id": resolve_plate_id(state),
        # Plate-clear gate (#939). Lives on the PrinterManager rather than PrinterState,
        # so surface it here — without this, WebSocket merges drop the flag and the
        # "Clear Plate" button only appears when the 30 s REST fallback poll runs.
        "awaiting_plate_clear": printer_manager.is_awaiting_plate_clear(printer_id) if printer_id else False,
    }
    # Add cover URL if there's an active print and printer_id is provided
    # Include PAUSE state so skip objects modal can show cover
    if printer_id and state.state in ("RUNNING", "PAUSE") and state.gcode_file:
        result["cover_url"] = f"/api/v1/printers/{printer_id}/cover"
    else:
        result["cover_url"] = None
    # Surface the display name + model so WS consumers (gcode viewer printer
    # selector) can render proper labels on the initial snapshot without racing
    # a separate /api/v1/printers fetch (#963 follow-up). PrinterInfo only
    # carries name/serial_number; the model comes through via the `model` arg.
    if printer_id:
        _printer_info = printer_manager.get_printer(printer_id)
        if _printer_info is not None:
            result["name"] = _printer_info.name
    if model:
        result["model"] = model
    return result


# Global printer manager instance
printer_manager = PrinterManager()


async def init_printer_connections(db: AsyncSession):
    """Initialize connections to all active printers.

    Connections are started concurrently. ``connect_printer()`` is non-blocking
    apart from a fixed 1-second settle wait — ``BambuMQTTClient.connect()`` only
    calls ``connect_async()`` + ``loop_start()``, so the handshake happens on a
    background thread and the coroutine's only real cost is that ``sleep(1)``. A
    serial loop therefore spent one whole second per printer inside the FastAPI
    lifespan *before* the ASGI server begins serving: on a large farm that was
    ~100s of dead air before port 8000 responded (issue #2572, reporter's
    93-printer farm). Gathering overlaps the settle waits so the whole step takes
    ~1s regardless of fleet size. Exceptions are isolated per printer with
    ``return_exceptions=True`` so one unreachable row can't abort the rest — or
    startup itself, which the old serial loop's un-caught await would have done.

    All columns ``connect_printer`` reads are eagerly loaded by the SELECT above
    and touched synchronously before its trailing ``await``, so no concurrent
    lazy-load is triggered on the shared session.
    """
    result = await db.execute(select(Printer).where(Printer.is_active.is_(True)))
    printers = result.scalars().all()

    outcomes = await asyncio.gather(
        *(printer_manager.connect_printer(printer) for printer in printers),
        return_exceptions=True,
    )
    for printer, outcome in zip(printers, outcomes, strict=True):
        if isinstance(outcome, Exception):
            logger.warning(
                "Failed to connect printer %s (%s) at startup: %s",
                printer.id,
                printer.name,
                outcome,
            )