Repainting: signals that change after they were shown

A signal repaints when what the chart shows afterwards differs from what a trader saw at the time. A backtest of such a signal earns money nobody could have earned. Two different things can repaint, and Monte-Neo checks both.

History: repaint_history

The signal of a closed bar must stay the same when more bars arrive. The check compares the signals of prefixes that follow one another (the table as it grew), the table extended by synthetic bars, and the table with its last three bars restated. Any difference fails the check, which rejects the strategy, and the details say how many bars were redrawn, how far back, and where it started.

Typical sources: ZigZag and swing pivots that a later bar confirms, Williams fractals without a confirmation delay, rolling(center=True), Ichimoku's lagging span, whole-series statistics, find_peaks over the whole array, a higher-timeframe bar used before it closed.

--repaint auto (the default) uses about a dozen prefixes plus the last bars; strict uses about four times as many; off skips both repaint checks.

The forming bar: repaint_live

The bar's high, low, close and volume are replaced by their state at 0, 25, 50 and 75 % of the bar, along a path open -> low -> high -> close (an up bar) or open -> high -> low -> close (a down bar).

• A signal that cannot change in any of these states is known at the bar's open (it only reads closed bars): pass.
• A signal that changes is decided at the close. That is how every rule on the close works, and it is not a fault: act on it only after the bar closed, never on the forming bar. The check reports the flicker rate as information.
• With --signal-timing open you declare that the signal is known at the open. A signal that needs the bar's own prices then fails.

The engine always fills a signal on the next bar, so a closed-bar strategy is not credited with the bar it decided on.

Lint rules and fixes

repaint_zigzag, unconfirmed_pivot (find_peaks, argrelextrema), htf_without_shift (a resample(...) aggregate not shifted before it is used on lower-timeframe bars) and lookahead_on are warnings. monte-neo verify --suggest-fix shifts a higher-timeframe aggregate by one bar and switches lookahead off.

In discover

Every candidate and every canary passes the same gate; the gate also appends bars and restates the last ones. The winner's certificate carries both repaint rows, and the result reports confirmation: close.