Chemist Warehouse Price & Promo Change Monitor

Watch any set of Chemist Warehouse (chemistwarehouse.com.au) products and get only the changes: price rises and drops, promo movements (RRP changes and catalogue-promo flags — the raw signals behind CW's "1/2 Price" and "% OFF RRP" badges) and availability flips. Schedule it daily and pipe the change feed into alerts, repricing, or brand price-compliance reporting.

Chemist Warehouse is Australia's dominant pharmacy retailer and its aggressive half-price catalogue cycles move the whole health & beauty market. One-shot scrapers give you a snapshot; this monitor tells you what changed since yesterday — which is the question price-intel teams, health & beauty brands and resellers actually ask.

• First run seeds a baseline and emits nothing (clearly logged).
• Every later run emits one dataset record per changed field, nothing else.
• State lives in a named key-value store, so runs are independent and cheap.

Example change record

{
  "sku": "2477821",
  "name": "NIVEA Rich Nourishing Body Lotion 400ml",
  "field": "price",
  "oldValue": 9.99,
  "newValue": 5.99,
  "productUrl": "https://www.chemistwarehouse.com.au/buy/6631/nivea-rich-nourishing-body-lotion-moisturiser-48h-400ml",
  "detectedAt": "2026-08-31T01:46:46Z"
}

field is one of price (AUD), promo or availability (in_stock / out_of_stock / unavailable — the latter emitted once when a product disappears from the site).

promo values are captured raw as the site publishes them:

{ "rrpCents": 1000, "flags": ["in_catalogue"] }

rrpCents is the RRP in cents (price vs RRP is exactly how CW computes its "1/2 Price" and "% OFF RRP" badges) and flags is the raw product-flag list (in_catalogue, exclusive, …). No interpretation is applied, so your rules stay yours.

Input

Field	Type	Default	Notes
watchUrls	array	–	CW product page URLs (…/buy/<id>/<slug>)
watchQueries	array	–	Search terms; every product returned joins the watch list
maxItems	integer	500	Cap on change records emitted per run
maxProductsPerQuery	integer	25	Products each query may add (max 100)
stateStoreName	string	chemist-warehouse-monitor-state	Use different names for independent watch lists
proxyConfiguration	object	AU residential	The monitor talks to CW's public search API; the default is the safe choice

Note: Chemist Warehouse pricing is national (no per-store prices), so there is no store selector — one clean feed per product.

Use cases

1. Brand price compliance — a health & beauty brand watches watchQueries: ["nivea"] daily and gets alerted the moment CW discounts below MAP or a product enters the half-price catalogue (in_catalogue flag appears, RRP gap widens).
2. Reseller buying signals — a reseller watches high-velocity lines (watchQueries: ["panadol", "blackmores", "swisse"]) and buys stock the day a deep price drop lands, before the catalogue crowd.
3. Price intelligence feeds — an analytics team watches competitor SKU URLs and ingests the change feed into their warehouse; only deltas arrive, so the pipeline stays tiny.

Pricing events

• Actor start: $0.005 per run
• Item checked: $0.0002 per product per run
• Change detected: $0.012 per change record

A daily watch of 100 products costs about $0.025/run plus a cent per change — you pay for signal, not for pages.

Update promise

The monitor uses the retailer's own product-search backend (fast, stable, JSON). If Chemist Warehouse changes its storefront, the actor logs a clear schema-drift warning instead of crashing, and fixes ship promptly — monitors are only useful when they keep running.

Changelog

• 0.1 (2026-08-31) — Initial release: price / promo / availability change feed, named-KV baseline, first-run seeding, maxItems cap, AU residential proxy default.