Scanned, or named as not scanned.

A screener that refuses to lie

Most screeners silently skip what they can’t compute and present the result as complete. QuantumCat’s screener is built on the opposite contract: every symbol is either scanned, or named as not scanned. Symbols that error, time out or don’t exist on your live feed broker are reported in the footer by name — never presented as “didn’t match”.

What you can screen on

Family	Examples
Price & fields	LTP, OHLC, volume, OI, spread, day change %, gap %, previous-day high/low/close, running day high/low.
Indicators	EMA/SMA/WMA, RSI, MACD, Bollinger, ATR, ADX/DI, Supertrend, Stochastic, CCI, Williams %R, MFI, OBV, CVD, opening-range high/low, highest/lowest lookbacks — composable (EMA of RSI), with per-indicator timeframe overrides.
Session anchors	Session VWAP, ORB, gap — anchored at the instrument’s own exchange session (NSE 09:15, MCX 09:00, CDS 09:00), verified to actually reach the open before they’re trusted.
Option-chain metrics	PCR, max pain, ATM IV, call/put OI — each instrument screened against its own chain.
Universes	Watchlist, NIFTY 50, NIFTY 500, all F&O underlyings, every listed equity, or a custom list.

The honesty rules

• Closed candles only — a forming bar can’t produce a match that evaporates at the close, on every timeframe including the daily one: today’s half-built bar is dropped, so a 1-day screen is judged on settled sessions and a promoted 1-day bot fires the same day the screen matched. “Today so far” is still expressible — and only where you ask for it — with the live-tick fields ltp and dayChangePct, which append the current print past the last closed bar instead of rewriting it.
• Three-valued logic — insufficient data is UNKNOWN, not false: it can’t satisfy a NOT, and a screen whose data never arrived says so instead of rendering “no matches”.
• Time conditions judge the bot’s clock — a time-window rule evaluates at the last bar-grid decision instant, so screener, bot and backtest agree on the same instrument at the same moment.
• Every match shows its numbers — the row chips carry the actual scanned values (“RSI(14) < 30 — 27.4 vs 30”), and each row’s X-ray explains the full condition tree.
• Provenance is tracked — results are stamped with the exact filter that produced them; edit the filter and the table is flagged stale until you Run again (auto-rescan pauses rather than scan a half-edited filter).
• Broker-aware — the roster resolves against your live feed broker’s own instrument namespace, retries transient rate-limits with gentler sweeps, and paces itself under the broker’s historical-data limits.

Auto-rescan re-runs your screen on a cadence and diff-flashes entrants and departures by name. Save screens, run them as bot filters, or send any row to chart, chain or ticket in a keystroke.