feat(trading-signals): add signals to trend, channel and volume indicators

[bennycode]

Adds getSignal() to indicators that have a well-known directional reading but did not expose one.

Indicator	BULLISH	BEARISH	SIDEWAYS
SuperTrend	its own trend	its own trend	–
VolatilityStop	its own signal	its own signal	–
PSAR	dots below price (long)	dots above price (short)	–
Aroon	Up above Down	Down above Up	equal
IchimokuCloud	conversion above base	conversion below base	equal
LinearRegression	positive slope	negative slope	flat
Alligator	lips > teeth > jaw	lips < teeth < jaw	lines intertwined
KeltnerChannels	close above the upper line	close below the lower line	inside
DonchianChannels	candle sets the channel high	candle sets the channel low	both or neither
VWAP	close above VWAP	close below VWAP	equal
HTTrendline	price above the trendline	price below the trendline	equal

The Alligator docs used to say it emits no signal; they now describe the reading instead.

Signals are judged when a result is set

Most of these readings compare a result with the price of its bar (Keltner, Donchian, VWAP, HTTrendline) or with internal state (PSAR's direction). The signal base classes could not support that: they evaluated the signal lazily from a result value, and evaluated the previous result for hasChanged at a moment when the indicator already held the next bar. That is why Bollinger Bands, Acceleration Bands and Gann HiLo each hand-roll their own price and result history.

TrendIndicatorSeries and TrendIndicator now evaluate the signal once, when a result is set, and keep that state together with the one before it. A replacement keeps the state of the bar before the replaced one, and rollbackLastResult() rolls the signal back too. Existing signals keep their behavior, because they either depend on the result alone or update their internals before setting the result. Tests in Indicator.test.ts pin the new timing and fail against the old base classes. Bollinger Bands, Acceleration Bands and Gann HiLo could move onto the base classes in a follow-up.

Not included

SwingIndex, AccumulativeSwingIndex, WAD, ChandelierExit and ChandeKrollStop stay without a signal. Their docs explain why on purpose: the Swing Index is noisy on its own, the ASI is read with drawn trendlines, WAD is read for divergence, and which stop matters depends on the trade the caller holds. NVI and PVI stay without one too, because they are read against a long moving average of themselves that would need its own setting.

Behavior changes

Results are unchanged. The indicators above now have getSignal(), so the CLI prints a signal for them. SuperTrend, VolatilityStop, Aroon, IchimokuCloud, LinearRegression, Alligator, KeltnerChannels and DonchianChannels extend TrendIndicator instead of TechnicalIndicator, and PSAR, VWAP and HTTrendline extend TrendIndicatorSeries instead of IndicatorSeries.

[Copilot]

Copilot review overview

🟡 Changes recommended

Keltner and Alligator boundary semantics lack mutation-resistant equality coverage.

Review effort: Balanced
Findings: 2

Open (2)

• Cover single-equal adjacent pairs in fan ordering tests · New
• Add equality-boundary coverage for SIDEWAYS channel checks · New

What changed in this PR

Adds directional signals to eleven trend, channel, and volume indicators while making signal history replacement-safe.

Changes:

• Adds bullish, bearish, and sideways signal calculations.
• Evaluates and caches signals when results are produced.
• Adds signal-state, replacement, and rollback tests.

File	Description
base/​Indicator.ts	Caches signal history with results.
base/​Indicator.test.ts	Tests signal timing and rollback.
trend/​ALLIGATOR/​Alligator.ts	Adds line-order signals.
trend/​ALLIGATOR/​Alligator.test.ts	Tests Alligator signals.
trend/​AROON/​Aroon.ts	Adds Aroon comparison signals.
trend/​AROON/​Aroon.test.ts	Tests Aroon signals.
trend/​HT/​HTTrendline.ts	Compares price with trendline.
trend/​HT/​HTTrendline.test.ts	Tests trendline signals.
trend/​ICHIMOKU/​IchimokuCloud.ts	Compares conversion and base lines.
trend/​ICHIMOKU/​IchimokuCloud.test.ts	Tests Ichimoku signals.
trend/​LINREG/​LinearRegression.ts	Derives signals from slope.
trend/​LINREG/​LinearRegression.test.ts	Tests slope signals.
trend/​PSAR/​PSAR.ts	Exposes PSAR direction.
trend/​PSAR/​PSAR.test.ts	Tests PSAR signals.
trend/​SUPERTREND/​SuperTrend.ts	Exposes SuperTrend direction.
trend/​SUPERTREND/​SuperTrend.test.ts	Tests SuperTrend signals.
trend/​VSTOP/​VolatilityStop.ts	Exposes stop direction.
trend/​VSTOP/​VolatilityStop.test.ts	Tests stop signals.
trend/​VWAP/​VWAP.ts	Compares close with VWAP.
trend/​VWAP/​VWAP.test.ts	Tests VWAP signals.
volatility/​DC/​DonchianChannels.ts	Adds channel-breakout signals.
volatility/​DC/​DonchianChannels.test.ts	Tests Donchian signals.
volatility/​KC/​KeltnerChannels.ts	Adds channel-boundary signals.
volatility/​KC/​KeltnerChannels.test.ts	Tests Keltner signals.

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