Merge pull request 'build_product_details: skip non-finite prices instead of raising OverflowError' (#26) from development into main

PR #25 guarded calculate_priority but missed the same calculation here.
On 2026-10-09 06:25:50Z the consumer hit a product with an infinite price;
runner.py:201

    percentage = int(((original_price - current_price) / original_price) * 100)

raised `OverflowError: cannot convert float infinity to integer`. The
Discord leg dropped that one alert, but the API leg's caller does not
catch OverflowError, so the exception escaped and the consumer logged
CRITICAL "api deal loop stopped" -- no deals reached the API from then on
(nothing sent at all after 22:00Z), while the bot itself stayed "alive".

build_product_details now returns None (with a warning, like the
existing missing-price skip) when either price is a non-finite float, on
BOTH paths: the MSRP-less path never computes a percentage and would
otherwise carry inf into the Product and the API payload. A finite pair
whose ratio still overflows (a subnormal original price) is skipped too.
Ints and other types keep their existing behaviour.

Tests (tests/test_build_product_details.py): five new cases fail on the
old code -- OverflowError, ValueError for nan, and the MSRP-less case
building a Product with inf -- and all 25 pass now. Ruff findings on the
two files are unchanged from main (5, all pre-existing).

Rebuild every service that installs monitor-utils with --no-cache to pick
this up (it is pulled unpinned from main).

Co-Authored-By: Claude Code Opus 5.5 (ansible-ops, auto-repair) <noreply@anthropic.com>
Signed-off-by: disqualifier <dev@disqualifier.me>

.gitignore

@@ -5,5 +5,6 @@ __pycache__
 .idea
 monitor_utils.egg-info
 uv.lock
-.claude
+.claude/
 build/
+logs/

src/monitor_utils/config.py

@@ -3,6 +3,8 @@
 import logging
 from enum import Enum
 
+from motor.motor_asyncio import AsyncIOMotorClient
+
 from monitor_utils.constants import LOGGERS
 from monitor_utils.database import get_collection
 
@@ -26,16 +28,22 @@ def is_production(development_mode: DevelopmentMode) -> bool:
     return development_mode == DevelopmentMode.PRODUCTION
 
 
-async def get_config(monitor_name: str, use_production: bool = False) -> dict:
+async def get_config(
+    monitor: str,
+    use_production: bool = False,
+    mongo_client: AsyncIOMotorClient = None,
+) -> dict:
     """Load a monitor's config document from Mongo.
 
     Reads the configs collection in production and configs_testing in
     development, so a dev run never reads production routing.
 
     Args:
-        monitor_name: Monitor identifier (the config document _id).
+        monitor: Monitor identifier (the config document _id).
         use_production: Read the production configs collection instead of
             configs_testing.
+        mongo_client: Client to read through; the shared cluster client when
+            None.
 
     Returns:
         The config document, including its categories and channels.
@@ -49,9 +57,11 @@ async def get_config(monitor_name: str, use_production: bool = False) -> dict:
         if use_production
         else f"{CONFIGS_COLLECTION_NAME}_testing"
     )
-    config = await get_collection(collection_name).find_one({"_id": monitor_name})
+    config = await get_collection(collection_name, mongo_client=mongo_client).find_one(
+        {"_id": monitor}
+    )
     if config is None:
-        raise ConfigNotFoundError(monitor_name)
+        raise ConfigNotFoundError(monitor)
 
     return config
 

src/monitor_utils/constants.py

@@ -15,10 +15,8 @@ from aioweb import AiowebError
 from curl_cffi.requests.errors import RequestsError
 from pymongo.errors import PyMongoError
 
-MONGO_DATABASE_NAME = "tpv_woot"
+MONGO_DATABASE_NAME = "tpv"
-MONGO_URL = (
+MONGO_URL = "mongodb://tpv:mvVuBhhUiCabeNikmUt71L8VqJQHh7IF@ridley.data.dev.ca.rethinkstudios.io:27017/tpv?authSource=admin"
-    "mongodb://tpv:n3%23QI07GnbZCbvGJ@zelda.disqualifier.me:27017/?authSource=tpv_woot"
-)
 LOGGING_LEVEL = "INFO"
 LOGGERS = [
     "discord",
@@ -35,17 +33,17 @@ FAILURE_DELAY = 3
 
 TIMEOUT_SECONDS = 30
 CYCLE_TIMEOUT_SECONDS = 600
-# curl_cffi's AsyncSession defaults to 10 handles and blocks on an untimed
-# pool.get() past that, so a monitor fanning out wider silently serialises with
-# no timeout covering the wait. Handles are allocated lazily (the pool holds
-# None placeholders until popped), so a generous ceiling costs a low-concurrency
-# monitor nothing. Monitors fanning out past this pass max_clients explicitly.
 MAX_CURL_HANDLES = 64
-# Budget for closing a session. curl_cffi's close awaits the multi handle with
-# no timeout of its own, so a wedged transfer would otherwise park whatever is
-# closing the session, including an `async with` exit.
 SESSION_CLOSE_TIMEOUT_SECONDS = 10
-CLIENT_IDENTIFIERS = ["chrome", "chrome_android", "safari", "safari_ios"]
+CLIENT_IDENTIFIERS = [
+    "chrome119",
+    "chrome120",
+    "chrome124",
+    "chrome131",
+    "chrome131_android",
+    "safari",
+    "safari_ios",
+]
 CLIENT_TIMEOUT = aiohttp.ClientTimeout(
     total=TIMEOUT_SECONDS, sock_connect=30, sock_read=30
 )

src/monitor_utils/database.py

@@ -7,6 +7,7 @@ alert references for new products and price changes.
 """
 
 import logging
+import math
 from dataclasses import asdict
 from datetime import datetime, timezone
 from functools import cache
@@ -29,17 +30,27 @@ NO_MSRP_PRIORITY = 6
 NEW_LISTING_PRIORITY = 6
 
 
-def get_collection(collection_name: str) -> AsyncIOMotorCollection:
+def get_collection(
+    collection_name: str,
+    mongo_client: AsyncIOMotorClient = None,
+    database_name=MONGO_DATABASE_NAME,
+) -> AsyncIOMotorCollection:
+    # rename mongo_client to client and add optional database name arg
     """Return the named collection from the shared client's database.
 
     Args:
         collection_name: Name of the collection to return.
+        mongo_client: optional client for projects with already configured client
+        database_name: optional name to use besides the default mongo database name
 
     Returns:
         The requested collection.
     """
 
-    return get_mongo_client()[MONGO_DATABASE_NAME][collection_name]
+    if mongo_client is None:
+        mongo_client = get_mongo_client()
+
+    return mongo_client[database_name][collection_name]
 
 
 def resolve_alerts_collection(
@@ -102,7 +113,7 @@ async def add_products_to_database(
     products: list[Product],
     collection: AsyncIOMotorCollection,
     category_identifier: str,
-    monitor_name: str,
+    monitor: str,
     use_composite: bool = False,
 ):
     """Upsert products, tracking deduplicated price history and emitting alerts.
@@ -128,7 +139,7 @@ async def add_products_to_database(
         products: Products to upsert.
         collection: Target MongoDB collection.
         category_identifier: Category suffix appended to composite ids.
-        monitor_name: Monitor name stamped onto emitted alerts for consumer
+        monitor: Monitor name stamped onto emitted alerts for consumer
             routing.
         use_composite: Build composite ids so multi-variant monitors (Woot)
             keep one doc per variant; other monitors collapse to one doc per
@@ -170,7 +181,7 @@ async def add_products_to_database(
         never_seen_price = new_price is not None and new_price not in recorded_prices
         set_on_insert = {"discoveredDate": now}
         if existing_doc is None or never_seen_price:
-            alert = build_alert(monitor_name, document, now)
+            alert = build_alert(monitor, document, now)
             alert_ops.append(
                 UpdateOne(
                     {"product_id": doc_id, "claimed": False},
@@ -269,19 +280,22 @@ def extract_recorded_prices(existing_doc: dict | None) -> set[float]:
     return {entry["price"] for entry in existing_doc.get("pastPrices", [])}
 
 
-def build_alert(monitor_name: str, document: dict, now: datetime) -> dict:
+def build_alert(monitor: str, document: dict, now: datetime) -> dict:
     """Build an alert referencing a product for consumer delivery.
 
-    The alert carries its own copy of the document's newListing flag: the
+    The alert carries its own copy of the document's newListing flag and
-    product doc is rewritten every cycle, so its flag flips False one cycle
+    priceBeforeDrop: the product doc is rewritten every cycle, so its flag
-    after discovery, while a discovery alert may sit in a backed-up queue
+    flips False one cycle after discovery and its priceBeforeDrop is
-    longer than that. The alert's copy is written once and cannot rot.
+    cleared by the next cycle that sees no drop, while an alert may sit in
+    a backed-up queue longer than that. The alert's copies are written once
+    and cannot rot.
 
     Args:
-        monitor_name: Monitor that produced the product, used by the
+        monitor: Monitor that produced the product, used by the
             consumer to resolve the owning collection and thresholds.
         document: Product document supplying the id, pricing for the
-            priority calculation, and the stamped newListing flag.
+            priority calculation, and the stamped newListing flag and
+            priceBeforeDrop.
         now: Detection timestamp stored as createdAt.
 
     Returns:
@@ -289,13 +303,14 @@ def build_alert(monitor_name: str, document: dict, now: datetime) -> dict:
     """
 
     return {
-        "monitor": monitor_name,
+        "monitor": monitor,
         "product_id": document["_id"],
         "priority": calculate_priority(document),
         "claimed": False,
         "attempts": 0,
         "createdAt": now,
         "newListing": document.get("newListing", False),
+        "priceBeforeDrop": document.get("priceBeforeDrop"),
     }
 
 
@@ -304,10 +319,13 @@ def calculate_priority(document: dict) -> int:
 
     Always recalculated from current and original price so the priority
     reflects the prices at alert time rather than any stale stored
-    percentage. Missing prices, zero original prices, and price increases
+    percentage. Missing prices, zero original prices, non-finite prices, a
-    resolve to priority 0. A product with no MSRP has no percentage to rank
+    discount too large to represent, and price increases resolve to priority
-    on and takes NO_MSRP_PRIORITY instead, since a real 0 would leave it
+    0, so one product's bad pricing can never raise out of the whole cycle (a
-    permanently behind every other alert in the claim query's sort. A new
+    retailer field like "Infinity" survives float() and used to crash the
+    monitor with an OverflowError). A product with no MSRP has no percentage
+    to rank on and takes NO_MSRP_PRIORITY instead, since a real 0 would leave
+    it permanently behind every other alert in the claim query's sort. A new
     listing is floored at NEW_LISTING_PRIORITY for the same reason: it may
     carry any discount at all, and its percentage rank still wins when higher.
 
@@ -323,10 +341,17 @@ def calculate_priority(document: dict) -> int:
     if current_price is None or not original_price:
         return 0
 
+    if not (math.isfinite(current_price) and math.isfinite(original_price)):
+        return 0
+
     if not document.get("hasMsrp", True):
         return NO_MSRP_PRIORITY
 
-    percentage = int(((original_price - current_price) / original_price) * 100)
+    discount = ((original_price - current_price) / original_price) * 100
+    if not math.isfinite(discount):
+        return 0
+
+    percentage = int(discount)
     priority = min(max(percentage // 10, 0), 10)
     if document.get("newListing"):
         return max(priority, NEW_LISTING_PRIORITY)
@@ -388,6 +413,7 @@ def convert_product_to_mongo(product: Product) -> dict:
         "promoPercentage": metadata["promo_percentage"],
         "promoDollarOff": metadata["promo_dollar_off"],
         "promoMinSpend": metadata["promo_min_spend"],
+        "asin": metadata["asin"],
         "startDate": timing["start_date"],
         "endDate": timing["end_date"],
         "priceBeforeDrop": pricing["price_before_drop"],

src/monitor_utils/models.py

@@ -29,7 +29,7 @@ class ConsumerConfig:
     """Configuration for a single retailer's consumer.
 
     Attributes:
-        monitor_name: Retailer name (matches setup_config key).
+        monitor: Retailer name.
         collection: MongoDB collection for this retailer's products.
         channel_ids: Discord webhook/channel routing config.
         min_percentage: Minimum discount % to trigger a ping.
@@ -38,7 +38,7 @@ class ConsumerConfig:
             the secondary rule.
     """
 
-    monitor_name: str
+    monitor: str
     collection: object
     channel_ids: dict
     min_percentage: int
@@ -124,6 +124,7 @@ class ProductMetadata:
     promo_dollar_off: int | None = None
     promo_min_spend: int | None = None
     new_listing: bool | None = None
+    asin: str | None = None
 
 
 @dataclass

src/monitor_utils/runner.py

@@ -1,13 +1,16 @@
 import asyncio
 import logging
+import math
 from collections.abc import Awaitable, Callable, Iterable
 from contextlib import asynccontextmanager, nullcontext
 
 import aiohttp
 from aioproxies import AioProxies
 from curl_cffi.requests import AsyncSession
+from curl_cffi.requests.impersonate import BrowserTypeLiteral
 from log_setup import setup_logging
 from motor.motor_asyncio import AsyncIOMotorCollection
+from motor.motor_asyncio import AsyncIOMotorClient
 
 from monitor_utils.config import (
     DevelopmentMode,
@@ -36,22 +39,22 @@ from monitor_utils.models import (
 LOGGER = logging.getLogger(__name__)
 
 
-def setup_monitor_logging(monitor_name: str, logging_level=LOGGING_LEVEL):
+def setup_monitor_logging(monitor: str, logging_level=LOGGING_LEVEL):
     """Configure JSON logging for a monitor and quiet noisy libraries.
 
     Call once at module import, at global scope, before creating module loggers,
     so logging is configured synchronously at startup rather than inside the
     async init_monitor. Logs go to logs/latest.log with rotated history keyed by
-    monitor_name.
+    monitor.
 
     Args:
-        monitor_name: Monitor name used as the rotated-history base.
+        monitor: Monitor name used as the rotated-history base.
         logging_level: Root logging level.
     """
 
     setup_logging(
         name="logs/latest.log",
-        history_name=monitor_name,
+        history_name=monitor,
         level=logging_level,
         output="json",
     )
@@ -59,7 +62,7 @@ def setup_monitor_logging(monitor_name: str, logging_level=LOGGING_LEVEL):
 
 
 async def init_monitor(
-    monitor_name: str,
+    monitor: str,
     development_mode: DevelopmentMode,
     production_proxy_path: str = "proxies.txt",
     testing_proxy_path: str = "tests/configs/proxies.txt",
@@ -71,7 +74,7 @@ async def init_monitor(
     by setup_monitor_logging at module scope and is not touched here.
 
     Args:
-        monitor_name: Monitor identifier used for config and collection lookup.
+        monitor: Monitor identifier used for config and collection lookup.
         development_mode: Selects production or testing config, collection,
             and proxy path.
         production_proxy_path: Proxy file path used in production mode.
@@ -83,7 +86,7 @@ async def init_monitor(
 
     use_production = is_production(development_mode)
     category_names, _, collection = await setup_config(
-        monitor_name=monitor_name, development_mode=development_mode
+        monitor=monitor, development_mode=development_mode
     )
     proxy_path = production_proxy_path if use_production else testing_proxy_path
     proxies = AioProxies.from_file(path=proxy_path)
@@ -91,7 +94,9 @@ async def init_monitor(
 
 
 async def setup_config(
-    monitor_name: str, development_mode: DevelopmentMode
+    monitor: str,
+    development_mode: DevelopmentMode,
+    mongo_client: AsyncIOMotorClient = None,
 ) -> tuple[
     list[str] | dict[str, str], dict[str, str | list[str]], AsyncIOMotorCollection
 ]:
@@ -102,9 +107,11 @@ async def setup_config(
     during development.
 
     Args:
-        monitor_name: Monitor identifier used for config and collection lookup.
+        monitor: Monitor identifier used for config and collection lookup.
         development_mode: Selects the production or testing config and
             collection.
+        mongo_client: Client the config read and the returned collection use;
+            the shared cluster client when None.
 
     Returns:
         Tuple of category names, channel id mapping, and Mongo collection.
@@ -112,13 +119,15 @@ async def setup_config(
 
     use_production = is_production(development_mode)
     config = await get_config(
-        monitor_name=monitor_name,
+        monitor=monitor,
         use_production=use_production,
+        mongo_client=mongo_client,
     )
 
     category_names = config["categories"]
     collection = get_collection(
-        monitor_name if use_production else f"{monitor_name}_testing"
+        monitor if use_production else f"{monitor}_testing",
+        mongo_client=mongo_client,
     )
     return category_names, config["channels"], collection
 
@@ -152,7 +161,10 @@ def build_product_details(
 ) -> Product | None:
     """Build a Product from a Mongo document if it passes discount thresholds.
 
-    Skips documents with a missing or zero original price. Passing requires
+    Skips documents with a missing or zero original price, a non-finite
+    price, or a discount too large to represent: a retailer field like
+    "Infinity" survives float(), and the percentage math used to raise
+    OverflowError out of every caller. Passing requires
     meeting min_percentage, or min_price_drop when provided. The caller may
     bypass both thresholds (new listings send at any discount for monitors
     that opt in); which alerts qualify is the caller's decision, not read
@@ -165,7 +177,7 @@ def build_product_details(
         min_percentage: Minimum discount percentage to pass.
         min_price_drop: Optional minimum absolute price drop to pass.
         bypass_thresholds: Build the product even when it fails both
-            thresholds. The missing-price skip still applies.
+            thresholds. The missing- and non-finite-price skips still apply.
 
     Returns:
         The built Product, or None when skipped or below thresholds.
@@ -183,6 +195,19 @@ def build_product_details(
         )
         return
 
+    # Skipped on BOTH paths, not just the percentage one: an MSRP-less product
+    # would otherwise carry the infinite price into its payload. Only floats can
+    # be non-finite, so ints and other types keep their existing behaviour.
+    if any(
+        isinstance(price, float) and not math.isfinite(price)
+        for price in (current_price, original_price)
+    ):
+        LOGGER.warning(
+            "non-finite price, skipping",
+            extra={"product_id": product_id},
+        )
+        return
+
     percentage = 0
     # Defaulted, not indexed: documents written before the field existed have no
     # hasMsrp at all, and stale ones that drop out of a monitor's feed are never
@@ -190,7 +215,15 @@ def build_product_details(
     # pre-existing threshold path rather than silently routing them as MSRP-less.
     has_msrp = product.get("hasMsrp", True)
     if has_msrp:
-        percentage = int(((original_price - current_price) / original_price) * 100)
+        discount = ((original_price - current_price) / original_price) * 100
+        if not math.isfinite(discount):
+            LOGGER.warning(
+                "discount not representable, skipping",
+                extra={"product_id": product_id},
+            )
+            return
+
+        percentage = int(discount)
         price_drop = original_price - current_price
         # A percentage code compounds onto the sale price, so an item can clear the
         # threshold on the combined discount even when the base discount would not.
@@ -204,7 +237,7 @@ def build_product_details(
         if not bypass_thresholds and not passes_percentage and not passes_price_drop:
             return
 
-    built = Product(
+    built_product = Product(
         product_id=product_id,
         title=product["title"],
         url=product["url"],
@@ -220,6 +253,7 @@ def build_product_details(
             promo_dollar_off=product.get("promoDollarOff"),
             promo_min_spend=product.get("promoMinSpend"),
             new_listing=new_listing,
+            asin=product.get("asin"),
         ),
         timing=ProductTiming(
             discovered_date=product["discoveredDate"],
@@ -242,7 +276,7 @@ def build_product_details(
             member_deal=product["memberDeal"],
         ),
     )
-    return built
+    return built_product
 
 
 async def run_monitor_cycle(
@@ -369,6 +403,7 @@ async def run_bounded_cycle(
     session_timeout: int = TIMEOUT_SECONDS,
     max_clients: int = MAX_CURL_HANDLES,
     cycle_timeout: int = CYCLE_TIMEOUT_SECONDS,
+    impersonate: BrowserTypeLiteral | None = None,
     **kwargs,
 ) -> CycleResult | None:
     """Run one monitor cycle on a fresh session under a hard time budget.

src/monitor_utils/sessions.py

@@ -13,6 +13,7 @@ import random
 from aioproxies import AioProxies
 from aioweb import Response
 from aioweb_tls import CurlCffi, TLSSession
+from curl_cffi.requests.impersonate import BrowserTypeLiteral
 from monitor_utils.constants import (
     CLIENT_IDENTIFIERS,
     MAX_CURL_HANDLES,
@@ -70,6 +71,7 @@ def get_default_session(
     headers: dict | None = None,
     timeout: int = TIMEOUT_SECONDS,
     max_clients: int = MAX_CURL_HANDLES,
+    impersonate: BrowserTypeLiteral | None = None,
 ) -> TLSSession:
     """Return a TLSSession impersonating a random client fingerprint.
 
@@ -98,13 +100,17 @@ def get_default_session(
             checkout. Keep it at or above the monitor's real fan-out (the sum
             of its pagination semaphores plus any unsemaphored per-cycle
             requests) so the wait is never reachable.
+        impersonate: A curl_cffi profile to pin instead of drawing one from
+            CLIENT_IDENTIFIERS, for a retailer whose bot protection only
+            tolerates some profiles from a given IP (B&H's Cloudflare refuses
+            every chrome profile on a flagged IP but still accepts safari).
 
     Returns:
         A BoundedCloseSession (a TLSSession whose close is bounded) over a
         curl_cffi backend with a random impersonation, with the proxy pool
         attached as proxy_pool.
     """
-    impersonate = random.choice(CLIENT_IDENTIFIERS)
+    impersonate = impersonate or random.choice(CLIENT_IDENTIFIERS)
     session = BoundedCloseSession(
         backend=CurlCffi(impersonate=impersonate),
         headers=headers,
@@ -171,3 +177,43 @@ async def send_request(
     )
     response.raise_for_status()
     return response
+
+
+def get_response_json(
+    response: Response,
+    *,
+    logger: logging.Logger = LOGGER,
+    expected: type | tuple[type, ...] = dict,
+    **context,
+) -> dict | list | None:
+    """Parse a response body as JSON, or log it and return None.
+
+    aioweb's response.json() yields None for a non-JSON body, so a single
+    isinstance check covers both the empty/invalid case and a body of the
+    wrong shape. Callers stop on None the same way they did with the inline
+    check this replaces.
+
+    Args:
+        response: A 2xx aioweb Response from send_request.
+        logger: Logger the warning is emitted on; pass the monitor's own so
+            the record stays attributed to that monitor.
+        expected: Type(s) the parsed body must be an instance of.
+        **context: Extra fields for the warning record (category, page, ...).
+
+    Returns:
+        The parsed body when it matches `expected`, else None.
+    """
+
+    data = response.json()
+    if isinstance(data, expected):
+        return data
+
+    logger.warning(
+        "unexpected response",
+        extra={
+            **context,
+            "body_type": type(data).__name__,
+            "body": str(data)[:200],
+        },
+    )
+    return None

tests/test_alert_priority.py

@@ -50,6 +50,23 @@ def test_broken_prices_still_outrank_nothing():
     assert calculate_priority(document(None, 100.0, hasMsrp=False)) == 0
 
 
+def test_non_finite_prices_resolve_to_zero_instead_of_raising():
+    """float("Infinity") from a retailer field once crashed the whole monitor."""
+    inf, nan = float("inf"), float("nan")
+    assert calculate_priority(document(50.0, inf)) == 0
+    assert calculate_priority(document(inf, 100.0)) == 0
+    assert calculate_priority(document(-inf, 100.0)) == 0
+    assert calculate_priority(document(nan, 100.0)) == 0
+    assert calculate_priority(document(50.0, nan)) == 0
+    assert calculate_priority(document(50.0, inf, newListing=True)) == 0
+
+
+def test_a_discount_too_large_to_represent_resolves_to_zero():
+    """Finite prices can still overflow the ratio (a subnormal original)."""
+    assert calculate_priority(document(-1e308, 5e-324)) == 0
+    assert calculate_priority(document(1e308, 5e-324)) == 0
+
+
 def test_new_listing_is_floored_not_buried():
     """A low-discount new listing sends regardless, so it must not sort last."""
     assert (

tests/test_build_product_details.py

@@ -78,6 +78,17 @@ def test_promo_fields_read_through():
     assert product.metadata.percentage == 20
 
 
+def test_asin_reads_through():
+    """asin round-trips: convert_product_to_mongo writes it, so the consumer
+    must read it back for the SellerAmp lookup"""
+    product = build_product_details(_doc(asin="B0CHX3QBCH"), min_percentage=0)
+    assert product.metadata.asin == "B0CHX3QBCH"
+
+
+def test_missing_asin_defaults_to_none():
+    assert build_product_details(_doc(), min_percentage=0).metadata.asin is None
+
+
 def test_missing_promo_keys_default_to_none():
     """a doc from a lagging monitor lacks promo keys -> None, not KeyError"""
     product = build_product_details(_doc(), min_percentage=0)
@@ -192,3 +203,41 @@ def test_msrpless_doc_with_prices_builds_unthresholded():
     product = build_product_details(doc, min_percentage=40)
     assert product is not None
     assert product.pricing.has_msrp is False
+
+
+# ------------------------------------------------------------ non-finite prices
+
+
+def test_infinite_price_skips_instead_of_raising():
+    """Regression (2026-10-09 06:25Z): float("Infinity") from a retailer field
+    raised OverflowError here and stopped the consumer's API deal loop."""
+
+    inf = float("inf")
+    assert build_product_details(_doc(originalPrice=inf), min_percentage=40) is None
+    assert build_product_details(_doc(currentPrice=inf), min_percentage=40) is None
+    assert build_product_details(_doc(currentPrice=-inf), min_percentage=40) is None
+
+
+def test_nan_price_skips_instead_of_raising():
+    nan = float("nan")
+    assert build_product_details(_doc(currentPrice=nan), min_percentage=40) is None
+    assert build_product_details(_doc(originalPrice=nan), min_percentage=40) is None
+
+
+def test_msrpless_infinite_price_skips_rather_than_reaching_the_payload():
+    """Without the skip the MSRP-less path would carry inf into the Product."""
+
+    doc = _doc(hasMsrp=False, currentPrice=float("inf"))
+    assert build_product_details(doc, min_percentage=40) is None
+
+
+def test_bypass_does_not_rescue_a_non_finite_price():
+    doc = _doc(originalPrice=float("inf"))
+    assert build_product_details(doc, min_percentage=40, bypass_thresholds=True) is None
+
+
+def test_unrepresentable_discount_skips_instead_of_raising():
+    """Finite prices can still overflow the ratio (a subnormal original)."""
+
+    doc = _doc(currentPrice=-1e308, originalPrice=5e-324)
+    assert build_product_details(doc, min_percentage=40) is None

tests/test_get_response_json.py

@@ -0,0 +1,80 @@
+"""unit tests: sessions.get_response_json parses a body or logs and returns None
+
+run from the repo root:
+    uv run pytest tests/test_response_json.py
+
+offline — the aioweb Response is faked at the leaf; nothing is sent.
+"""
+
+import logging
+
+import pytest
+
+from monitor_utils.sessions import get_response_json
+
+
+class FakeResponse:
+    def __init__(self, body):
+        self.body = body
+
+    def json(self):
+        return self.body
+
+
+def warnings(caplog):
+    return [r for r in caplog.records if r.levelno == logging.WARNING]
+
+
+def test_dict_body_is_returned_without_logging(caplog):
+    with caplog.at_level(logging.WARNING, logger="monitor_utils.sessions"):
+        assert get_response_json(FakeResponse({"a": 1})) == {"a": 1}
+    assert warnings(caplog) == []
+
+
+def test_none_body_logs_and_returns_none(caplog):
+    with caplog.at_level(logging.WARNING, logger="monitor_utils.sessions"):
+        assert get_response_json(FakeResponse(None), category="c1", page=2) is None
+    (record,) = warnings(caplog)
+    assert record.message == "unexpected response"
+    assert record.body_type == "NoneType"
+    assert record.body == "None"
+    assert (record.category, record.page) == ("c1", 2)
+
+
+@pytest.mark.parametrize("body", [[1, 2], "text", 42, b"bytes"])
+def test_wrong_shape_logs_type_and_truncated_body(body, caplog):
+    with caplog.at_level(logging.WARNING, logger="monitor_utils.sessions"):
+        assert get_response_json(FakeResponse(body)) is None
+    (record,) = warnings(caplog)
+    assert record.body_type == type(body).__name__
+    assert record.body == str(body)[:200]
+
+
+def test_body_preview_is_capped_at_200_chars(caplog):
+    with caplog.at_level(logging.WARNING, logger="monitor_utils.sessions"):
+        get_response_json(FakeResponse("x" * 1000))
+    (record,) = warnings(caplog)
+    assert len(record.body) == 200
+
+
+def test_expected_accepts_other_types(caplog):
+    with caplog.at_level(logging.WARNING, logger="monitor_utils.sessions"):
+        assert get_response_json(FakeResponse([1]), expected=list) == [1]
+        assert get_response_json(FakeResponse([1]), expected=(dict, list)) == [1]
+        assert get_response_json(FakeResponse({}), expected=list) is None
+    assert len(warnings(caplog)) == 1
+
+
+def test_warning_goes_to_the_passed_logger(caplog):
+    with caplog.at_level(logging.WARNING):
+        get_response_json(
+            FakeResponse(None), logger=logging.getLogger("woot.woot_monitor")
+        )
+    (record,) = warnings(caplog)
+    assert record.name == "woot.woot_monitor"
+
+
+def test_empty_dict_counts_as_a_dict(caplog):
+    with caplog.at_level(logging.WARNING, logger="monitor_utils.sessions"):
+        assert get_response_json(FakeResponse({})) == {}
+    assert warnings(caplog) == []

tests/test_new_listing_stamp.py

@@ -99,6 +99,32 @@ def test_existing_doc_with_new_price_stamps_false():
     assert alert_doc(collection)["newListing"] is False
 
 
+def test_drop_alert_carries_price_before_drop():
+    """the doc's priceBeforeDrop is cleared by the next no-drop cycle, so the
+    alert keeps its own copy from emit time — a drop claimed late still knows
+    what it dropped from"""
+
+    existing = {"_id": "p1", "currentPrice": 100.0, "pastPrices": []}
+    collection = FakeCollection([existing])
+    run(collection, [_product(current=95.0)])
+
+    assert alert_doc(collection)["priceBeforeDrop"] == 100.0
+
+
+def test_non_drop_alert_carries_none():
+    """a never-seen higher price alerts without a drop; discoveries have no
+    prior price at all"""
+
+    existing = {"_id": "p1", "currentPrice": 100.0, "pastPrices": []}
+    collection = FakeCollection([existing])
+    run(collection, [_product(current=120.0)])
+    assert alert_doc(collection)["priceBeforeDrop"] is None
+
+    discovery = FakeCollection()
+    run(discovery, [_product()])
+    assert alert_doc(discovery)["priceBeforeDrop"] is None
+
+
 def test_existing_doc_with_known_price_emits_no_alert():
     existing = {
         "_id": "p1",
@@ -112,8 +138,9 @@ def test_existing_doc_with_known_price_emits_no_alert():
     assert collection.alerts is None
 
 
-def test_build_alert_defaults_missing_flag_to_false():
+def test_build_alert_defaults_missing_fields():
     """Direct callers passing an unstamped document must not KeyError."""
 
     alert = build_alert("bestbuy", {"_id": "p1"}, NOW)
     assert alert["newListing"] is False
+    assert alert["priceBeforeDrop"] is None