bambuddy/backend/app/api/routes/spoolman.py

"""Spoolman integration API routes."""

import json
import logging
from typing import Literal

from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel
from sqlalchemy import delete, select, text
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from backend.app.api.routes._spoolman_helpers import _map_spoolman_spool, spoolman_net_weight
from backend.app.api.routes.spoolman_inventory import _clear_stale_tag_links
from backend.app.core.auth import (
    RequestPrinterScope,
    RequirePermissionIfAuthEnabled,
    RequirePrinterPermissionIfAuthEnabled,
)
from backend.app.core.database import get_db
from backend.app.core.permissions import Permission
from backend.app.core.printer_scope import PrinterScope
from backend.app.models.printer import Printer
from backend.app.models.settings import Settings
from backend.app.models.spool_assignment import SpoolAssignment
from backend.app.models.spoolman_k_profile import SpoolmanKProfile
from backend.app.models.spoolman_slot_assignment import SpoolmanSlotAssignment
from backend.app.models.user import User
from backend.app.services import slot_unlink_grace
from backend.app.services.printer_manager import printer_manager
from backend.app.services.slicer_filament_resolver import resolve_slicer_filament
from backend.app.services.slot_nozzle import resolve_slot_nozzle
from backend.app.services.spool_filament_preset import resolve_spoolman_preset
from backend.app.services.spoolman import (
    SpoolmanClientError,
    SpoolmanNotFoundError,
    SpoolmanUnavailableError,
    close_spoolman_client,
    get_spoolman_client,
    init_spoolman_client,
)
from backend.app.utils.filament_ids import (
    GENERIC_FILAMENT_IDS,
    filament_id_to_setting_id,
    normalize_slicer_filament,
)
from backend.app.utils.filament_types import nozzle_temp_range, printer_filament_type

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/spoolman", tags=["spoolman"])


class SpoolmanStatus(BaseModel):
    """Spoolman connection status."""

    enabled: bool
    connected: bool
    url: str | None
    # Spoolman 0.27+ links tags natively; the settings offer the migration then.
    native_tags: bool = False


class SkippedSpool(BaseModel):
    """Information about a skipped spool during sync."""

    location: str
    reason: Literal["No RFID tag and no slot assignment"]
    filament_type: str | None = None
    color: str | None = None


class SyncResult(BaseModel):
    """Result of a Spoolman sync operation."""

    success: bool
    synced_count: int
    skipped_count: int = 0
    skipped: list[SkippedSpool] = []
    errors: list[str]


async def get_spoolman_settings(db: AsyncSession) -> dict:
    """Get Spoolman settings from database.

    Returns:
        Dict with keys: enabled, url, sync_mode, disable_weight_sync
    """
    settings = {
        "enabled": False,
        "url": "",
        "sync_mode": "auto",
        "disable_weight_sync": False,
    }

    result = await db.execute(select(Settings))
    for setting in result.scalars().all():
        if setting.key == "spoolman_enabled":
            settings["enabled"] = setting.value.lower() == "true"
        elif setting.key == "spoolman_url":
            settings["url"] = setting.value
        elif setting.key == "spoolman_sync_mode":
            settings["sync_mode"] = setting.value
        elif setting.key == "spoolman_disable_weight_sync":
            settings["disable_weight_sync"] = setting.value.lower() == "true"

    return settings


@router.get("/status", response_model=SpoolmanStatus)
async def get_spoolman_status(
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.FILAMENTS_READ),
):
    """Get Spoolman integration status.

    ``connected`` answers "does the configured Spoolman respond?", which means
    asking it. It used to answer "has some earlier request in this process left
    a client object lying around?" -- and roughly twenty call sites build one
    lazily, so the answer depended on which page happened to load first rather
    than on anything about Spoolman.

    That mattered because the UI reads this one flag twice: it offers Connect
    only while disconnected, and the AMS sync section only while connected.
    Saving the Settings page initialises a client as a side effect of syncing
    locations, so enabling Spoolman there reported "connected" without anything
    having been set up, hiding the Connect button and revealing a sync that then
    failed on every slot (issue #2903). Registration no longer depends on that
    button, but the flag was still describing Bambuddy's memory rather than the
    integration, so it is now resolved the same way every other route resolves
    it -- including the stale-URL check, so editing the URL is not reported
    against the old host.
    """
    sm = await get_spoolman_settings(db)
    enabled, url = sm["enabled"], sm["url"]

    connected = False
    native_tags = False
    if enabled and url:
        client = await get_spoolman_client()
        if not client or client.base_url != url.rstrip("/"):
            try:
                client = await init_spoolman_client(url)
            except ValueError as exc:
                logger.warning("Spoolman URL %r rejected by SSRF guard during status check: %s", url, exc)
                client = None
            except Exception as exc:
                # Every remaining way this can fail still answers the question:
                # replacing a client closes the previous one, and httpx's
                # aclose() is not guaranteed not to raise. A status poll that
                # 500s every 30 seconds is worse than one reporting what is
                # true either way -- that Spoolman could not be reached.
                logger.warning("Could not open a Spoolman client for %r during status check: %s", url, exc)
                client = None
        if client:
            connected = await client.health_check()
            # Asked once per client and cached, so the 30-second poll costs nothing more.
            native_tags = connected and await client.has_tag_api()

    return SpoolmanStatus(
        enabled=enabled,
        connected=connected,
        url=url if url else None,
        native_tags=native_tags,
    )


@router.post("/connect")
async def connect_spoolman(
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.SETTINGS_UPDATE),
):
    """Connect to Spoolman server using configured URL."""
    sm = await get_spoolman_settings(db)
    enabled, url = sm["enabled"], sm["url"]

    if not enabled:
        raise HTTPException(status_code=400, detail="Spoolman integration is not enabled")

    if not url:
        raise HTTPException(status_code=400, detail="Spoolman URL is not configured")

    try:
        client = await init_spoolman_client(url)
        connected = await client.health_check()

        if not connected:
            raise HTTPException(
                status_code=503,
                detail=f"Could not connect to Spoolman at {url}",
            )

        # Ensure the 'tag' extra field exists for RFID/UUID storage
        field_ok = await client.ensure_tag_extra_field()
        if not field_ok:
            logger.error("Spoolman tag extra field registration failed — NFC tag links may not persist")
        # Register slicer-preset extra fields (Spoolman rejects unknown extra keys).
        for field_name in ("bambu_slicer_filament", "bambu_slicer_filament_name"):
            if not await client.ensure_extra_field(field_name):
                logger.warning(
                    "Spoolman extra field %r registration failed — spool slicer-preset edits will return 502",
                    field_name,
                )

        return {"success": True, "message": f"Connected to Spoolman at {url}"}
    except ValueError as exc:
        logger.warning("Spoolman URL rejected: %s", exc)
        raise HTTPException(status_code=400, detail=str(exc)) from exc
    except Exception as e:
        logger.error("Failed to connect to Spoolman: %s", e)
        raise HTTPException(status_code=503, detail=str(e))


@router.post("/disconnect")
async def disconnect_spoolman(
    _: User | None = RequirePermissionIfAuthEnabled(Permission.SETTINGS_UPDATE),
):
    """Disconnect from Spoolman server."""
    await close_spoolman_client()
    return {"success": True, "message": "Disconnected from Spoolman"}


@router.post("/sync/{printer_id}", response_model=SyncResult)
async def sync_printer_ams(
    printer_id: int,
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePrinterPermissionIfAuthEnabled(Permission.FILAMENTS_UPDATE),
):
    """Sync AMS data from a specific printer to Spoolman."""
    # Check if Spoolman is enabled and connected
    # disable_weight_sync is deprecated (#1119); weight comes from per-print tracking.
    sm = await get_spoolman_settings(db)
    enabled, url = sm["enabled"], sm["url"]
    if not enabled:
        raise HTTPException(status_code=400, detail="Spoolman integration is not enabled")

    client = await get_spoolman_client()
    if not client:
        # Try to connect
        if url:
            client = await init_spoolman_client(url)
        else:
            raise HTTPException(status_code=400, detail="Spoolman URL is not configured")

    if not await client.health_check():
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    # Get printer info
    result = await db.execute(select(Printer).where(Printer.id == printer_id))
    printer = result.scalar_one_or_none()
    if not printer:
        raise HTTPException(status_code=404, detail="Printer not found")

    # Get current printer state with AMS data
    state = printer_manager.get_status(printer_id)
    if not state:
        raise HTTPException(status_code=404, detail="Printer not connected")

    if not state.raw_data:
        raise HTTPException(status_code=400, detail="No AMS data available")

    ams_data = state.raw_data.get("ams")
    if not ams_data:
        raise HTTPException(
            status_code=400,
            detail="No AMS data in printer state. Try triggering a slot re-read on the printer.",
        )

    # Sync each AMS tray to Spoolman
    synced = 0
    skipped: list[SkippedSpool] = []
    errors = []

    from backend.app.api.routes.settings import get_setting

    _auto_add_raw = await get_setting(db, "auto_add_unknown_rfid")
    auto_add_unknown_rfid = _auto_add_raw is None or _auto_add_raw.lower() == "true"

    # Handle different AMS data structures
    # Traditional AMS: list of {"id": N, "tray": [...]} dicts
    # H2D/newer printers: dict with different structure
    ams_units = []
    if isinstance(ams_data, list):
        ams_units = ams_data
    elif isinstance(ams_data, dict):
        # H2D format: check for "ams" key containing list, or "tray" key directly
        if "ams" in ams_data and isinstance(ams_data["ams"], list):
            ams_units = ams_data["ams"]
        elif "tray" in ams_data:
            # Single AMS unit format - wrap in list
            ams_units = [{"id": 0, "tray": ams_data.get("tray", [])}]
        else:
            logger.info("AMS dict keys for debugging: %s", list(ams_data.keys()))

    if not ams_units:
        raise HTTPException(
            status_code=400,
            detail=(
                "AMS data format not supported. Keys: "
                f"{list(ams_data.keys()) if isinstance(ams_data, dict) else type(ams_data).__name__}"
            ),
        )

    # OPTIMIZATION: Fetch all spools once before processing trays
    # This eliminates redundant API calls (one per tray) when syncing multiple trays
    logger.debug("[Printer %s] Fetching spools cache for sync...", printer.name)
    try:
        cached_spools = await client.get_spools()
        logger.debug("[Printer %s] Cached %d spools for batch sync", printer.name, len(cached_spools))
    except Exception as e:
        logger.error("[Printer %s] Failed to fetch spools cache after retries: %s", printer.name, e)
        raise HTTPException(
            status_code=503,
            detail=f"Failed to connect to Spoolman after multiple retries: {str(e)}",
        )

    # Load inventory weights as fallback (when AMS MQTT data lacks remain values)
    inv_weights: dict[tuple[int, int], float] = {}
    try:
        assign_result = await db.execute(
            select(SpoolAssignment)
            .options(selectinload(SpoolAssignment.spool))
            .where(SpoolAssignment.printer_id == printer_id)
        )
        for assignment in assign_result.scalars().all():
            spool = assignment.spool
            if spool and spool.label_weight > 0:
                remaining = max(0.0, spool.label_weight - (spool.weight_used or 0))
                inv_weights[(assignment.ams_id, assignment.tray_id)] = remaining
    except Exception as e:
        logger.debug("Could not load inventory weights for printer %s: %s", printer_id, e)

    # Load existing Spoolman slot assignments for the no-RFID fallback path
    spoolman_slot_map: dict[tuple[int, int], int] = {}
    try:
        slot_result = await db.execute(
            select(SpoolmanSlotAssignment).where(SpoolmanSlotAssignment.printer_id == printer_id)
        )
        for slot in slot_result.scalars().all():
            spoolman_slot_map[(slot.ams_id, slot.tray_id)] = slot.spoolman_spool_id
    except Exception as e:
        logger.warning("Could not load Spoolman slot assignments for printer %s: %s", printer_id, e)

    slot_changes: list[tuple[int, int, int]] = []  # (ams_id, tray_id, spoolman_spool_id)
    empty_slots: list[tuple[int, int]] = []  # (ams_id, tray_id) now empty

    for ams_unit in ams_units:
        if not isinstance(ams_unit, dict):
            continue

        ams_id = int(ams_unit.get("id", 0))
        trays = ams_unit.get("tray", [])

        for tray_data in trays:
            if not isinstance(tray_data, dict):
                continue

            tray_id_raw = int(tray_data.get("id", 0))
            tray = client.parse_ams_tray(ams_id, tray_data)
            if not tray:
                empty_slots.append((ams_id, tray_id_raw))
                continue

            spool_tag = (
                tray.tray_uuid
                if tray.tray_uuid and tray.tray_uuid != "00000000000000000000000000000000"
                else tray.tag_uid
            )

            hint = spoolman_slot_map.get((ams_id, tray.tray_id)) if not spool_tag else None

            try:
                inv_remaining = inv_weights.get((ams_id, tray.tray_id))
                sync_result = await client.sync_ams_tray(
                    tray,
                    printer.name,
                    db,
                    # Per-print tracking owns weight updates (#1119); manual sync
                    # only refreshes spool metadata + slot assignments here.
                    disable_weight_sync=True,
                    cached_spools=cached_spools,
                    inventory_remaining=inv_remaining,
                    spoolman_spool_id_hint=hint,
                    auto_add_unknown_rfid=auto_add_unknown_rfid,
                )
                if sync_result:
                    synced += 1
                    if sync_result.get("id"):
                        slot_changes.append((ams_id, tray.tray_id, sync_result["id"]))
                        spool_exists = any(s.get("id") == sync_result["id"] for s in cached_spools)
                        if not spool_exists:
                            cached_spools.append(sync_result)
                            logger.debug("Added newly created spool %s to cache", sync_result["id"])
                    logger.info(
                        "Synced %s from %s AMS %s tray %s", tray.tray_sub_brands, printer.name, ams_id, tray.tray_id
                    )
                elif spool_tag and not auto_add_unknown_rfid:
                    skipped.append(
                        SkippedSpool(
                            location=f"AMS {ams_id} T{tray.tray_id}",
                            reason="Auto-add disabled; add to inventory manually",
                            filament_type=tray.tray_type or None,
                            color=tray.tray_color[:6] if tray.tray_color else None,
                        )
                    )
                elif spool_tag:
                    errors.append(f"Spool not found in Spoolman: AMS {ams_id}:{tray.tray_id}")
                elif not hint:
                    skipped.append(
                        SkippedSpool(
                            location=f"AMS {ams_id} T{tray.tray_id}",
                            reason="No RFID tag and no slot assignment",
                            filament_type=tray.tray_type or None,
                            color=tray.tray_color[:6] if tray.tray_color else None,
                        )
                    )
            except Exception as e:
                error_msg = f"Error syncing AMS {ams_id} tray {tray.tray_id}: {e}"
                logger.error(error_msg)
                errors.append(error_msg)

    # Persist slot assignment changes to the local table
    if slot_changes or empty_slots:
        try:
            for ams_id, tray_id, spool_id in slot_changes:
                await db.execute(
                    text(
                        "INSERT INTO spoolman_slot_assignments"
                        " (printer_id, ams_id, tray_id, spoolman_spool_id)"
                        " VALUES (:printer_id, :ams_id, :tray_id, :spool_id)"
                        " ON CONFLICT(printer_id, ams_id, tray_id)"
                        " DO UPDATE SET spoolman_spool_id = excluded.spoolman_spool_id"
                    ),
                    {"printer_id": printer_id, "ams_id": ams_id, "tray_id": tray_id, "spool_id": spool_id},
                )
            for ams_id, tray_id in empty_slots:
                await db.execute(
                    delete(SpoolmanSlotAssignment).where(
                        SpoolmanSlotAssignment.printer_id == printer_id,
                        SpoolmanSlotAssignment.ams_id == ams_id,
                        SpoolmanSlotAssignment.tray_id == tray_id,
                    )
                )
            await db.commit()
        except Exception as e:
            await db.rollback()
            logger.error("Error persisting Spoolman slot assignments for printer %s: %s", printer_id, e)
            errors.append(f"Failed to persist slot assignments: {type(e).__name__}")

    return SyncResult(
        success=len(errors) == 0,
        synced_count=synced,
        skipped_count=len(skipped),
        skipped=skipped,
        errors=errors,
    )


@router.post("/sync-all", response_model=SyncResult)
async def sync_all_printers(
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.FILAMENTS_UPDATE),
    printer_scope: PrinterScope = RequestPrinterScope,
):
    """Sync AMS data from all connected printers to Spoolman."""
    # Check if Spoolman is enabled
    # disable_weight_sync is deprecated (#1119); weight comes from per-print tracking.
    sm = await get_spoolman_settings(db)
    enabled, url = sm["enabled"], sm["url"]
    if not enabled:
        raise HTTPException(status_code=400, detail="Spoolman integration is not enabled")

    client = await get_spoolman_client()
    if not client:
        if url:
            client = await init_spoolman_client(url)
        else:
            raise HTTPException(status_code=400, detail="Spoolman URL is not configured")

    if not await client.health_check():
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    # Get all active printers
    result = await db.execute(select(Printer).where(Printer.is_active.is_(True)))
    printers = [p for p in result.scalars().all() if printer_scope.allows(p.id)]

    total_synced = 0
    all_skipped: list[SkippedSpool] = []
    all_errors = []

    from backend.app.api.routes.settings import get_setting

    _auto_add_raw = await get_setting(db, "auto_add_unknown_rfid")
    auto_add_unknown_rfid = _auto_add_raw is None or _auto_add_raw.lower() == "true"

    # OPTIMIZATION: Fetch all spools once before processing ALL printers/trays
    # This eliminates redundant API calls across all printers
    logger.debug("Fetching spools cache for sync-all operation...")
    try:
        cached_spools = await client.get_spools()
        logger.debug("Cached %d spools for batch sync across %d printers", len(cached_spools), len(printers))
    except Exception as e:
        logger.error("Failed to fetch spools cache after retries: %s", e)
        raise HTTPException(
            status_code=503,
            detail=f"Failed to connect to Spoolman after multiple retries: {str(e)}",
        )

    # Load inventory assignments for weight fallback (when AMS MQTT data lacks remain values)
    # Key: (printer_id, ams_id, tray_id) → remaining_weight in grams
    inventory_weights: dict[tuple[int, int, int], float] = {}
    try:
        assign_result = await db.execute(select(SpoolAssignment).options(selectinload(SpoolAssignment.spool)))
        for assignment in assign_result.scalars().all():
            spool = assignment.spool
            if spool and spool.label_weight > 0:
                remaining = max(0.0, spool.label_weight - (spool.weight_used or 0))
                inventory_weights[(assignment.printer_id, assignment.ams_id, assignment.tray_id)] = remaining
    except Exception as e:
        logger.debug("Could not load inventory assignments for weight fallback: %s", e)

    # Load all Spoolman slot assignments for the no-RFID fallback
    # Key: (printer_id, ams_id, tray_id) → spoolman_spool_id
    all_slot_map: dict[tuple[int, int, int], int] = {}
    try:
        slot_result = await db.execute(select(SpoolmanSlotAssignment))
        for slot in slot_result.scalars().all():
            all_slot_map[(slot.printer_id, slot.ams_id, slot.tray_id)] = slot.spoolman_spool_id
    except Exception as e:
        logger.warning("Could not load Spoolman slot assignments: %s", e)

    # Collect slot changes across all printers for a single DB write at the end
    all_slot_changes: list[tuple[int, int, int, int]] = []  # (printer_id, ams_id, tray_id, spool_id)
    all_empty_slots: list[tuple[int, int, int]] = []  # (printer_id, ams_id, tray_id)

    for printer in printers:
        state = printer_manager.get_status(printer.id)
        if not state or not state.raw_data:
            continue

        ams_data = state.raw_data.get("ams")
        if not ams_data:
            continue

        # Handle different AMS data structures
        # Traditional AMS: list of {"id": N, "tray": [...]} dicts
        # H2D/newer printers: dict with different structure
        ams_units = []
        if isinstance(ams_data, list):
            ams_units = ams_data
        elif isinstance(ams_data, dict):
            # H2D format: check for "ams" key containing list, or "tray" key directly
            if "ams" in ams_data and isinstance(ams_data["ams"], list):
                ams_units = ams_data["ams"]
            elif "tray" in ams_data:
                # Single AMS unit format - wrap in list
                ams_units = [{"id": 0, "tray": ams_data.get("tray", [])}]
            else:
                logger.debug("Printer %s AMS dict keys: %s", printer.name, list(ams_data.keys()))

        if not ams_units:
            logger.debug("Printer %s has no AMS units to sync (type: %s)", printer.name, type(ams_data).__name__)
            continue

        for ams_unit in ams_units:
            if not isinstance(ams_unit, dict):
                logger.debug("Skipping non-dict AMS unit: %s", type(ams_unit))
                continue

            ams_id = int(ams_unit.get("id", 0))
            trays = ams_unit.get("tray", [])

            for tray_data in trays:
                if not isinstance(tray_data, dict):
                    continue

                tray_id_raw = int(tray_data.get("id", 0))
                tray = client.parse_ams_tray(ams_id, tray_data)
                if not tray:
                    all_empty_slots.append((printer.id, ams_id, tray_id_raw))
                    continue

                spool_tag = (
                    tray.tray_uuid
                    if tray.tray_uuid and tray.tray_uuid != "00000000000000000000000000000000"
                    else tray.tag_uid
                )

                hint = all_slot_map.get((printer.id, ams_id, tray.tray_id)) if not spool_tag else None

                try:
                    inv_remaining = inventory_weights.get((printer.id, ams_id, tray.tray_id))
                    sync_result = await client.sync_ams_tray(
                        tray,
                        printer.name,
                        db,
                        # Per-print tracking owns weight updates (#1119); manual
                        # sync-all only refreshes spool metadata + slot assignments.
                        disable_weight_sync=True,
                        cached_spools=cached_spools,
                        inventory_remaining=inv_remaining,
                        spoolman_spool_id_hint=hint,
                        auto_add_unknown_rfid=auto_add_unknown_rfid,
                    )
                    if sync_result:
                        total_synced += 1
                        if sync_result.get("id"):
                            all_slot_changes.append((printer.id, ams_id, tray.tray_id, sync_result["id"]))
                            spool_exists = any(s.get("id") == sync_result["id"] for s in cached_spools)
                            if not spool_exists:
                                cached_spools.append(sync_result)
                                logger.debug("Added newly created spool %s to cache", sync_result["id"])
                    elif spool_tag and not auto_add_unknown_rfid:
                        all_skipped.append(
                            SkippedSpool(
                                location=f"{printer.name} AMS {ams_id} T{tray.tray_id}",
                                reason="Auto-add disabled; add to inventory manually",
                                filament_type=tray.tray_type or None,
                                color=tray.tray_color[:6] if tray.tray_color else None,
                            )
                        )
                    elif spool_tag:
                        all_errors.append(f"Spool not found in Spoolman: {printer.name} AMS {ams_id}:{tray.tray_id}")
                    elif not hint:
                        all_skipped.append(
                            SkippedSpool(
                                location=f"{printer.name} AMS {ams_id} T{tray.tray_id}",
                                reason="No RFID tag and no slot assignment",
                                filament_type=tray.tray_type or None,
                                color=tray.tray_color[:6] if tray.tray_color else None,
                            )
                        )
                except Exception as e:
                    all_errors.append(f"{printer.name} AMS {ams_id}:{tray.tray_id}: {e}")

    # Persist slot assignment changes across all printers
    if all_slot_changes or all_empty_slots:
        try:
            for p_id, ams_id, tray_id, spool_id in all_slot_changes:
                await db.execute(
                    text(
                        "INSERT INTO spoolman_slot_assignments"
                        " (printer_id, ams_id, tray_id, spoolman_spool_id)"
                        " VALUES (:printer_id, :ams_id, :tray_id, :spool_id)"
                        " ON CONFLICT(printer_id, ams_id, tray_id)"
                        " DO UPDATE SET spoolman_spool_id = excluded.spoolman_spool_id"
                    ),
                    {"printer_id": p_id, "ams_id": ams_id, "tray_id": tray_id, "spool_id": spool_id},
                )
            for p_id, ams_id, tray_id in all_empty_slots:
                await db.execute(
                    delete(SpoolmanSlotAssignment).where(
                        SpoolmanSlotAssignment.printer_id == p_id,
                        SpoolmanSlotAssignment.ams_id == ams_id,
                        SpoolmanSlotAssignment.tray_id == tray_id,
                    )
                )
            await db.commit()
        except Exception as e:
            await db.rollback()
            logger.error("Error persisting Spoolman slot assignments: %s", e)
            all_errors.append(f"Failed to persist slot assignments: {type(e).__name__}")

    return SyncResult(
        success=len(all_errors) == 0,
        synced_count=total_synced,
        skipped_count=len(all_skipped),
        skipped=all_skipped,
        errors=all_errors,
    )


@router.get("/spools")
async def get_spools(
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.FILAMENTS_READ),
):
    """Get all spools from Spoolman."""
    sm = await get_spoolman_settings(db)
    enabled, url = sm["enabled"], sm["url"]
    if not enabled:
        raise HTTPException(status_code=400, detail="Spoolman integration is not enabled")

    client = await get_spoolman_client()
    if not client:
        if url:
            client = await init_spoolman_client(url)
        else:
            raise HTTPException(status_code=400, detail="Spoolman URL is not configured")

    if not await client.health_check():
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    spools = await client.get_spools()
    return {"spools": spools}


@router.get("/filaments")
async def get_filaments(
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.FILAMENTS_READ),
):
    """Get all filaments from Spoolman."""
    sm = await get_spoolman_settings(db)
    enabled, url = sm["enabled"], sm["url"]
    if not enabled:
        raise HTTPException(status_code=400, detail="Spoolman integration is not enabled")

    client = await get_spoolman_client()
    if not client:
        if url:
            client = await init_spoolman_client(url)
        else:
            raise HTTPException(status_code=400, detail="Spoolman URL is not configured")

    if not await client.health_check():
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    filaments = await client.get_filaments()
    return {"filaments": filaments}


class UnlinkedSpool(BaseModel):
    """A Spoolman spool that is not linked to any AMS tray."""

    id: int
    filament_name: str | None
    filament_vendor: str | None
    filament_material: str | None
    filament_color_hex: str | None
    remaining_weight: float | None
    location: str | None


@router.get("/spools/unlinked", response_model=list[UnlinkedSpool])
async def get_unlinked_spools(
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.FILAMENTS_READ),
):
    """Get all Spoolman spools not currently assigned to an AMS slot."""
    sm = await get_spoolman_settings(db)
    enabled, url = sm["enabled"], sm["url"]
    if not enabled:
        raise HTTPException(status_code=400, detail="Spoolman integration is not enabled")

    client = await get_spoolman_client()
    if not client:
        if url:
            client = await init_spoolman_client(url)
        else:
            raise HTTPException(status_code=400, detail="Spoolman URL is not configured")

    if not await client.health_check():
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    spools = await client.get_spools()

    # A spool is "assignable" iff it does not currently occupy an AMS slot.
    # Assignability is decided by the spoolman_slot_assignments ledger — NOT by
    # the presence of extra.tag. extra.tag is only an RFID/NFC matching key, and
    # OpenSpoolman writes its own NFC tag value into that same field (#1122);
    # treating any non-empty extra.tag as "linked" hid every OpenSpoolman-tagged
    # spool from this picker even when it occupied no slot. Both link_spool and
    # the AMS auto-sync upsert a row here for every occupied slot, so the ledger
    # is a complete record of what is actually assigned.
    assigned_result = await db.execute(select(SpoolmanSlotAssignment.spoolman_spool_id))
    assigned_spool_ids = set(assigned_result.scalars().all())

    unlinked = []
    for spool in spools:
        if spool["id"] in assigned_spool_ids:
            continue
        filament = spool.get("filament", {}) or {}
        unlinked.append(
            UnlinkedSpool(
                id=spool["id"],
                filament_name=filament.get("name"),
                filament_vendor=(filament.get("vendor") or {}).get("name"),
                filament_material=filament.get("material"),
                filament_color_hex=filament.get("color_hex"),
                remaining_weight=spool.get("remaining_weight"),
                location=spool.get("location"),
            )
        )

    return unlinked


@router.get("/spools/linked")
async def get_linked_spools(
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.FILAMENTS_READ),
):
    """Get a map of tag -> spool_id for all Spoolman spools that have a tag assigned."""
    sm = await get_spoolman_settings(db)
    enabled, url = sm["enabled"], sm["url"]
    if not enabled:
        raise HTTPException(status_code=400, detail="Spoolman integration is not enabled")

    client = await get_spoolman_client()
    if not client:
        if url:
            client = await init_spoolman_client(url)
        else:
            raise HTTPException(status_code=400, detail="Spoolman URL is not configured")

    if not await client.health_check():
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    spools = await client.get_spools()
    linked: dict[str, dict] = {}

    for spool in spools:
        # Check if spool has a tag in extra field
        extra = spool.get("extra", {}) or {}
        tag = extra.get("tag", "")
        if tag:
            # Remove quotes if present (JSON encoded string)
            clean_tag = tag.strip('"').upper()
            if clean_tag:
                linked[clean_tag] = {
                    "id": spool["id"],
                    "remaining_weight": spool.get("remaining_weight"),
                    # The spool's own net weight, falling back to the
                    # filament's; the key predates initial_weight (#3194).
                    "filament_weight": spoolman_net_weight(spool),
                }

    return {"linked": linked}


class LinkSpoolRequest(BaseModel):
    """Request to link a Spoolman spool to an AMS tag (tray_uuid or tag_uid)."""

    spool_tag: str | None = None
    tray_uuid: str | None = None
    tag_uid: str | None = None
    printer_id: int | None = None
    ams_id: int | None = None
    tray_id: int | None = None


@router.post("/spools/{spool_id}/link")
async def link_spool(
    spool_id: int,
    request: LinkSpoolRequest,
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.FILAMENTS_UPDATE),
    printer_scope: PrinterScope = RequestPrinterScope,
):
    """Link a Spoolman spool to an AMS tag by setting Spoolman extra.tag."""
    sm = await get_spoolman_settings(db)
    enabled, url = sm["enabled"], sm["url"]
    if not enabled:
        raise HTTPException(status_code=400, detail="Spoolman integration is not enabled")

    client = await get_spoolman_client()
    if not client:
        if url:
            client = await init_spoolman_client(url)
        else:
            raise HTTPException(status_code=400, detail="Spoolman URL is not configured")

    if not await client.health_check():
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    # Resolve and validate spool tag (supports tray_uuid=32 hex and tag_uid=16 hex)
    spool_tag = (request.spool_tag or request.tray_uuid or request.tag_uid or "").strip()
    if not spool_tag:
        raise HTTPException(status_code=400, detail="Missing spool tag (tray_uuid or tag_uid)")
    if len(spool_tag) not in (16, 32):
        raise HTTPException(status_code=400, detail="Invalid spool tag format (must be 16 or 32 hex characters)")
    try:
        int(spool_tag, 16)
    except ValueError:
        raise HTTPException(status_code=400, detail="Invalid spool tag format (must be hex)")

    if set(spool_tag) == {"0"}:
        raise HTTPException(status_code=400, detail="Invalid spool tag format (all-zero tag is not linkable)")

    spool_tag = spool_tag.upper()

    # Validate printer context when provided, but do NOT write spool.location —
    # that field is user-managed in Spoolman. Slot assignment is stored locally.
    printer_context: tuple[int, int, int] | None = None
    if request.printer_id is not None and request.ams_id is not None and request.tray_id is not None:
        printer_scope.ensure(request.printer_id)
        printer_result = await db.execute(select(Printer).where(Printer.id == request.printer_id))
        if not printer_result.scalar_one_or_none():
            raise HTTPException(status_code=404, detail="Printer not found")
        printer_context = (request.printer_id, request.ams_id, request.tray_id)

    try:
        # Spoolman 0.27+: a tray UUID also becomes a native tag of the spool. The
        # 16-character values this route takes are either a slot's fallback ID or
        # the AMS's padded chip UID - neither is what a reader sees, so they stay in
        # extra.tag only; the AMS sync adds the real chip UID when it reads the tag.
        # The native link goes first, as the step Spoolman can refuse, so a refusal
        # leaves extra.tag untouched; a failed extra.tag write takes back what was added.
        added_native = False
        if len(spool_tag) == 32 and await client.has_tag_api():
            before = await client.get_spool(spool_id)
            had = any(t.get("uid") == spool_tag for t in before.get("tags") or [])
            holder = await client.claim_native_tag(spool_id, spool_tag, "bambu")
            if holder is not None:
                logger.warning("Native tag %s belongs to spool %s, left there", spool_tag, holder)
            added_native = holder is None and not had
        try:
            await client.merge_spool_extra(spool_id, {"tag": json.dumps(spool_tag)})
        except Exception:
            if added_native:
                try:
                    await client.unlink_native_tag(spool_id, spool_tag)
                except (SpoolmanClientError, SpoolmanUnavailableError) as exc:
                    logger.warning("Could not take back native tag %s from spool %s: %s", spool_tag, spool_id, exc)
            raise
    except SpoolmanNotFoundError:
        raise HTTPException(status_code=404, detail="Spool not found in Spoolman")
    except SpoolmanClientError:
        raise HTTPException(status_code=502, detail="Spoolman rejected the request")
    except SpoolmanUnavailableError:
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    # Upsert slot assignment locally when printer context was supplied
    if printer_context:
        p_id, a_id, t_id = printer_context
        try:
            await db.execute(
                text(
                    "INSERT INTO spoolman_slot_assignments"
                    " (printer_id, ams_id, tray_id, spoolman_spool_id)"
                    " VALUES (:printer_id, :ams_id, :tray_id, :spool_id)"
                    " ON CONFLICT(printer_id, ams_id, tray_id)"
                    " DO UPDATE SET spoolman_spool_id = excluded.spoolman_spool_id"
                ),
                {"printer_id": p_id, "ams_id": a_id, "tray_id": t_id, "spool_id": spool_id},
            )
            await db.commit()
            slot_unlink_grace.forget_slot(p_id, a_id, t_id)
        except Exception as e:
            await db.rollback()
            logger.error(
                "Linked spool %s in Spoolman but failed to persist local slot assignment "
                "(printer=%s ams=%s tray=%s): %s",
                spool_id,
                p_id,
                a_id,
                t_id,
                e,
            )
            raise HTTPException(
                status_code=500,
                detail=(
                    "Spool linked in Spoolman but the local slot assignment could not be saved. "
                    "Please re-open the link dialog to retry."
                ),
            ) from e

    logger.info("Linked Spoolman spool %s to tag %s", spool_id, spool_tag)

    # #1457: clear stale tag links on OTHER spools still claiming this exact tag.
    # A given AMS-slot tag (RFID or deterministic fallback) belongs to one
    # physical spool; without this cleanup the previous holder's extra.tag
    # keeps it visible in the hover card / fill-level lookup.
    await _clear_stale_tag_links(
        client,
        tag=spool_tag,
        keep_spool_id=spool_id,
        log_context=(
            f"printer={printer_context[0]} ams={printer_context[1]} tray={printer_context[2]}"
            if printer_context
            else "via /spools/{id}/link"
        ),
    )

    # Auto-configure AMS slot via MQTT (best-effort; tag link and slot assignment already persisted)
    if printer_context:
        p_id, a_id, t_id = printer_context
        try:
            spool_data = await client.get_spool(spool_id)
            mapped = _map_spoolman_spool(spool_data)

            mqtt_client = printer_manager.get_client(p_id)
            if mqtt_client:
                # Spoolman's material is free text, so it arrives as whatever
                # the user typed there -- "PLA+", "PolyTerra PLA". The sub-brand
                # keeps that wording; the slot's type has to be one the printer
                # and the slicer know (issue #2902).
                material = mapped.get("material") or ""
                tray_type = printer_filament_type(material)
                brand = mapped.get("brand") or ""
                subtype = mapped.get("subtype") or ""
                if brand:
                    tray_sub_brands = f"{brand} {material} {subtype}".strip()
                elif subtype:
                    tray_sub_brands = f"{material} {subtype}".strip()
                else:
                    tray_sub_brands = material

                tray_color = (mapped.get("rgba") or "808080FF").upper()
                if len(tray_color) == 6:
                    tray_color = tray_color + "FF"

                # Pull printer state via printer_manager (mqtt_client.printer_state
                # was a non-existent attribute — the hasattr check silently
                # returned None, defeating every state-based lookup below).
                state = printer_manager.get_status(p_id)
                slot_nozzle = resolve_slot_nozzle(state, a_id, t_id, printer_manager.get_model(p_id))
                nozzle_diameter = slot_nozzle.diameter

                # Resolve the spool's own preset before falling back to a
                # generic material id. This path used to skip that entirely and
                # configure every linked slot as generic PLA/PETG, so a spool
                # with a preset set in inventory lost it the moment it was
                # linked by tag — the same defect #1713 fixed on the assign
                # path, in the function next door. The per-model override
                # cascade applies here for the same reason it does there: the
                # preset is bound to a printer model.
                slot_slicer_filament, slot_slicer_filament_name = await resolve_spoolman_preset(
                    db,
                    spoolman_spool_id=spool_id,
                    printer_model=printer_manager.get_model(p_id),
                    nozzle_diameter=nozzle_diameter,
                    fallback_filament=mapped.get("slicer_filament"),
                    fallback_name=mapped.get("slicer_filament_name"),
                )
                tray_info_idx, setting_id, sub_brand_override, type_override = await resolve_slicer_filament(
                    db=db,
                    current_user=None,
                    slicer_filament=slot_slicer_filament,
                    slicer_filament_name=slot_slicer_filament_name,
                    material=material,
                )
                if sub_brand_override:
                    tray_sub_brands = sub_brand_override
                if type_override:
                    tray_type = printer_filament_type(type_override)

                # The spool's own wording is tried first and the reduced type
                # only as a further fallback, so a material that already
                # resolves keeps resolving to the same id: "PETG HF" has its
                # own generic preset (GFG96) that reducing it to "PETG" would
                # trade away for GFG99.
                material_upper = material.upper().strip()
                if not tray_info_idx:
                    tray_info_idx = (
                        GENERIC_FILAMENT_IDS.get(material_upper)
                        or GENERIC_FILAMENT_IDS.get(material_upper.split("-")[0].split(" ")[0])
                        or GENERIC_FILAMENT_IDS.get(tray_type.upper())
                        or ""
                    )
                if tray_info_idx and not setting_id:
                    setting_id = filament_id_to_setting_id(tray_info_idx)

                temp_defaults = nozzle_temp_range(material, tray_type)
                temp_min = mapped.get("nozzle_temp_min") or temp_defaults[0]
                temp_max = temp_defaults[1]

                kp_result = await db.execute(
                    select(SpoolmanKProfile).where(
                        SpoolmanKProfile.spoolman_spool_id == spool_id,
                        SpoolmanKProfile.printer_id == p_id,
                    )
                )
                kp_rows = kp_result.scalars().all()
                slot_extruder = slot_nozzle.extruder

                # Prefer exact extruder match, fall back to extruder-agnostic kp
                # for the same nozzle. Hard-skip on extruder mismatch silently
                # dropped valid stored profiles when the AMS-extruder map
                # shifted since calibration.
                exact_kp = None
                fallback_kp = None
                for kp in kp_rows:
                    if kp.nozzle_diameter != nozzle_diameter or kp.cali_idx is None:
                        continue
                    if not slot_nozzle.flow_matches(kp.nozzle_type):
                        continue
                    if slot_extruder is not None and kp.extruder is not None and kp.extruder == slot_extruder:
                        exact_kp = kp
                        break
                    if fallback_kp is None:
                        fallback_kp = kp
                matching_kp = exact_kp or fallback_kp

                # Resolve printer-side calibration entry by cali_idx — the
                # printer keys its calibration table by filament_id, not by
                # setting_id. Stored kp.setting_id alone isn't enough.
                printer_kp = None
                if matching_kp and state and state.kprofiles:
                    for pkp in state.kprofiles:
                        if pkp.slot_id == matching_kp.cali_idx and pkp.nozzle_diameter == nozzle_diameter:
                            printer_kp = pkp
                            break

                # Realign slot's filament context to the kp's calibration
                # context so ams_filament_setting and extrusion_cali_sel
                # reference the same preset; otherwise the printer drops the
                # cali_idx to default. PFUS-prefix cloud-user presets are
                # rejected by the slicer in tray_info_idx — skip realignment
                # in that case.
                effective_tray_info_idx = tray_info_idx
                effective_setting_id = setting_id
                if printer_kp and printer_kp.filament_id:
                    if not printer_kp.filament_id.startswith("PFUS"):
                        effective_tray_info_idx = printer_kp.filament_id
                    if printer_kp.setting_id:
                        effective_setting_id = printer_kp.setting_id
                elif matching_kp and matching_kp.setting_id:
                    derived = normalize_slicer_filament(matching_kp.setting_id)[0]
                    if derived and not derived.startswith("PFUS"):
                        effective_tray_info_idx = derived
                    effective_setting_id = matching_kp.setting_id
                if effective_tray_info_idx != tray_info_idx or effective_setting_id != setting_id:
                    logger.info(
                        "Spoolman link: realigning tray_info_idx %r → %r, setting_id %r → %r (kp_id=%s, source=%s)",
                        tray_info_idx,
                        effective_tray_info_idx,
                        setting_id,
                        effective_setting_id,
                        matching_kp.id if matching_kp else None,
                        "printer" if printer_kp else "stored",
                    )

                mqtt_client.ams_set_filament_setting(
                    ams_id=a_id,
                    tray_id=t_id,
                    tray_info_idx=effective_tray_info_idx,
                    tray_type=tray_type,
                    tray_sub_brands=tray_sub_brands,
                    tray_color=tray_color,
                    nozzle_temp_min=temp_min,
                    nozzle_temp_max=temp_max,
                    setting_id=effective_setting_id,
                )

                if matching_kp and matching_kp.cali_idx is not None:
                    cali_filament_id = (
                        printer_kp.filament_id if printer_kp and printer_kp.filament_id else None
                    ) or effective_tray_info_idx
                    mqtt_client.extrusion_cali_sel(
                        ams_id=a_id,
                        tray_id=t_id,
                        cali_idx=matching_kp.cali_idx,
                        filament_id=cali_filament_id,
                        nozzle_diameter=nozzle_diameter,
                    )
                    logger.info(
                        "Spoolman link: applied K-profile cali_idx=%d "
                        "(kp_id=%d, filament_id=%s) for spool %d on printer %d AMS%d-T%d",
                        matching_kp.cali_idx,
                        matching_kp.id,
                        cali_filament_id,
                        spool_id,
                        p_id,
                        a_id,
                        t_id,
                    )
                else:
                    from backend.app.api.routes.inventory import _find_tray_in_ams_data  # noqa: PLC0415

                    live_tray = None
                    if state and state.raw_data:
                        ams_raw = state.raw_data.get("ams", [])
                        if isinstance(ams_raw, dict):
                            ams_raw = ams_raw.get("ams", [])
                        live_tray = _find_tray_in_ams_data(ams_raw, a_id, t_id)
                    live_cali_idx = (live_tray or {}).get("cali_idx")
                    if live_cali_idx is not None and live_cali_idx >= 0:
                        mqtt_client.extrusion_cali_sel(
                            ams_id=a_id,
                            tray_id=t_id,
                            cali_idx=live_cali_idx,
                            filament_id=effective_tray_info_idx,
                            nozzle_diameter=nozzle_diameter,
                        )

                logger.info(
                    "Auto-configured AMS slot ams=%d tray=%d after linking Spoolman spool %d on printer %d",
                    a_id,
                    t_id,
                    spool_id,
                    p_id,
                )
        except (SpoolmanNotFoundError, SpoolmanUnavailableError) as e:
            logger.warning(
                "Could not fetch Spoolman spool %d for MQTT configure after tag link: %s",
                spool_id,
                e,
            )
        except Exception:
            logger.exception(
                "Failed to auto-configure AMS slot after linking Spoolman spool %d (printer=%d ams=%d tray=%d)",
                spool_id,
                p_id,
                a_id,
                t_id,
            )

    return {"success": True, "message": f"Spool {spool_id} linked to AMS tag"}


@router.post("/spools/{spool_id}/unlink")
async def unlink_spool(
    spool_id: int,
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.FILAMENTS_UPDATE),
):
    """Unlink a Spoolman spool from AMS by clearing Spoolman extra.tag."""
    sm = await get_spoolman_settings(db)
    enabled, url = sm["enabled"], sm["url"]
    if not enabled:
        raise HTTPException(status_code=400, detail="Spoolman integration is not enabled")

    client = await get_spoolman_client()
    if not client:
        if url:
            client = await init_spoolman_client(url)
        else:
            raise HTTPException(status_code=400, detail="Spoolman URL is not configured")

    if not await client.health_check():
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    # Spoolman PATCHes the extra dict by MERGING with the existing keys —
    # popping "tag" from a copy of the dict and sending the rest doesn't
    # clear it; Spoolman keeps the old value because the key wasn't in the
    # payload. To actually clear a key we must explicitly send it as the
    # JSON-encoded empty string ('""'), which the read-side filters in
    # _map_spoolman_spool and get_linked_spools strip via .strip('"').
    #
    # merge_spool_extra acquires extra_lock(spool_id) internally — wrapping
    # this call in another `async with client.extra_lock(spool_id)` would
    # deadlock (asyncio.Lock is not reentrant).
    try:
        await client.merge_spool_extra(spool_id, {"tag": json.dumps("")})
        # And the native tags, so an unlinked spool is found by none of them.
        if await client.has_tag_api():
            await client.unlink_all_native_tags(await client.get_spool(spool_id))
    except SpoolmanNotFoundError:
        raise HTTPException(status_code=404, detail="Spool not found in Spoolman")
    except SpoolmanClientError:
        raise HTTPException(status_code=502, detail="Spoolman rejected the request")
    except SpoolmanUnavailableError:
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    # Remove local slot assignment for this spool (all slots — a spool can only be in one at a time)
    try:
        await db.execute(delete(SpoolmanSlotAssignment).where(SpoolmanSlotAssignment.spoolman_spool_id == spool_id))
        await db.commit()
    except Exception:
        await db.rollback()
        logger.exception("DB error removing slot assignment for spool %s", spool_id)
        raise HTTPException(status_code=500, detail="Failed to remove local slot assignment")

    logger.info("Unlinked Spoolman spool %s", spool_id)
    return {"success": True, "message": f"Spool {spool_id} unlinked from AMS"}


class CreateSpoolFromSlotRequest(BaseModel):
    printer_id: int
    ams_id: int
    tray_id: int


@router.post("/spools/from-slot")
async def create_spool_from_slot(
    req: CreateSpoolFromSlotRequest,
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.FILAMENTS_UPDATE),
    printer_scope: PrinterScope = RequestPrinterScope,
):
    """Explicit user action: create a Spoolman spool from an AMS slot's current tray data.

    Used by the "+ Add to inventory" affordance when auto_add_unknown_rfid is disabled —
    the user looked at the slot and chose to register it. Calls sync_ams_tray with the
    auto-add override on so the spool is created even when the global setting is off.
    """
    sm = await get_spoolman_settings(db)
    if not sm["enabled"]:
        raise HTTPException(status_code=400, detail="Spoolman integration is not enabled")

    client = await get_spoolman_client()
    if not client:
        if sm["url"]:
            client = await init_spoolman_client(sm["url"])
        else:
            raise HTTPException(status_code=400, detail="Spoolman URL is not configured")

    if not await client.health_check():
        raise HTTPException(status_code=503, detail="Spoolman is not reachable")

    printer_scope.ensure(req.printer_id)
    result = await db.execute(select(Printer).where(Printer.id == req.printer_id))
    printer = result.scalar_one_or_none()
    if not printer:
        raise HTTPException(status_code=404, detail="Printer not found")

    state = printer_manager.get_status(req.printer_id)
    if not state or not state.raw_data:
        raise HTTPException(status_code=404, detail="Printer not connected or no state available")

    ams_data = state.raw_data.get("ams")
    ams_units: list[dict] = []
    if isinstance(ams_data, list):
        ams_units = ams_data
    elif isinstance(ams_data, dict):
        if "ams" in ams_data and isinstance(ams_data["ams"], list):
            ams_units = ams_data["ams"]
        elif "tray" in ams_data:
            ams_units = [{"id": 0, "tray": ams_data.get("tray", [])}]

    tray = None
    for unit in ams_units:
        if not isinstance(unit, dict):
            continue
        if int(unit.get("id", -1)) != req.ams_id:
            continue
        for t in unit.get("tray", []):
            if isinstance(t, dict) and int(t.get("id", -1)) == req.tray_id:
                tray = client.parse_ams_tray(req.ams_id, t)
                break
        if tray:
            break

    if not tray:
        raise HTTPException(status_code=400, detail="Slot is empty or has no readable tray data")

    # Same ghost-spool guard as the inventory route: no tag → no stable
    # identity → confirm would just create a fresh Spoolman row per push.
    from backend.app.services.spool_tag_matcher import is_valid_tag

    if not is_valid_tag(tray.tag_uid or "", tray.tray_uuid or ""):
        raise HTTPException(status_code=400, detail="Slot has no RFID tag")

    sync_result = await client.sync_ams_tray(
        tray,
        printer.name,
        db,
        disable_weight_sync=True,
        auto_add_unknown_rfid=True,
    )
    if not sync_result:
        raise HTTPException(status_code=500, detail="Spoolman did not create a spool from the slot")

    # Persist the slot assignment so the new spool shows on the slot tile.
    # If this fails, surface a 500 — silently returning success while the
    # binding rolled back leaves the user thinking the spool was added,
    # then watching the modal re-fire on the next MQTT push.
    if sync_result.get("id"):
        try:
            await db.execute(
                text(
                    "INSERT INTO spoolman_slot_assignments"
                    " (printer_id, ams_id, tray_id, spoolman_spool_id)"
                    " VALUES (:printer_id, :ams_id, :tray_id, :spool_id)"
                    " ON CONFLICT(printer_id, ams_id, tray_id)"
                    " DO UPDATE SET spoolman_spool_id = excluded.spoolman_spool_id"
                ),
                {
                    "printer_id": req.printer_id,
                    "ams_id": req.ams_id,
                    "tray_id": req.tray_id,
                    "spool_id": sync_result["id"],
                },
            )
            await db.commit()
            slot_unlink_grace.forget_slot(req.printer_id, req.ams_id, req.tray_id)
        except Exception as exc:
            await db.rollback()
            logger.exception("Failed to persist Spoolman slot assignment")
            raise HTTPException(
                status_code=500,
                detail=f"Spool created in Spoolman but slot assignment failed: {exc}",
            ) from exc

    return {"success": True, "spool_id": sync_result.get("id")}