v0.3 Gate: Streaming/Stateful API (real-time first)

[TDamiao]

Goal

Ship a production-ready streaming/stateful API so users can process ticks/candles in real time without passing full arrays.

Ideal usage direction:

const rsi = RSI({ period: 14 });
rsi.next(45.23);
rsi.next(46.10);

Why this matters

• Direct integration with websocket price feeds.
• Lower latency and allocations for live strategies.
• Strong differentiation vs array-only TA libraries.

Scope

• Define and document canonical stateful constructor style for v0.3 (factory or class-like API).
• Cover RSI/EMA/SMA in streaming form with consistent behavior.
• Keep/reset internal state deterministically.

Acceptance criteria

• Streaming APIs for RSI, EMA, and SMA are available and documented.
• next(value) behavior is deterministic, including warmup and reset semantics.
• Streaming outputs match batch implementations on overlapping non-null windows (default tolerance 1e-10).
• README includes at least one websocket-like streaming example.

Test plan

• Unit tests for warmup, reset, invalid inputs, and edge cases.
• Parity tests against batch functions for RSI/EMA/SMA.
• Golden/compat updates when applicable.

[TDamiao]

Progresso do Gate #2: Streaming/Stateful API

Implementacao inicial concluida nesta etapa:

• createSMA(period) adicionado com next(value) + reset().
• createEMA(period) adicionado com next(value) + reset().
• Paridade batch/stateful coberta em testes para SMA, EMA e RSI.
• Semantica de reset() validada em testes para recomputacao deterministica.
• Validacao de input invalido adicionada para API stateful.
• README atualizado com uso stateful e exemplo websocket-like.

PR

• feat(stateful): add streaming SMA/EMA APIs with parity and reset coverage #10

Validacao executada

• npm.cmd run build
• node --test --test-concurrency=1 --test-isolation=none test/contracts.test.mjs
• node --test --test-concurrency=1 --test-isolation=none test/golden.test.mjs

Checklist do #2 (estado atual)

• Streaming para RSI, EMA, SMA
• next(value) deterministico + warmup definido por comportamento de batch
• reset() deterministico
• Paridade stateful vs batch (1e-10)
• Exemplo de uso real-time no README
• Revisao e merge dos PRs empilhados

[TDamiao]

Gate concluido no merge dos PRs #12 (stateful streaming APIs) e #11 (compat policy consolidada em release train). Release publicado em v0.3.0: https://github.com/TDamiao/ta-crypto/releases/tag/v0.3.0