refactor(exchange): declare retry policy per endpoint with a @retry decorator

[bennycode]

Why

Both API clients configured retries through axios-retry interceptors that had to reverse-map failed request URLs/config back to policy. Trading212API's getRetryDelay matched URLs via string comparison — a design that already produced one silent bug (strict === missing paginated nextPagePath URLs — see the apology comment it carried), and every new endpoint risked silently falling through to the default delay.

What

@retry method decorator (TC39 standard mode, packages/exchange/src/util/retry.ts): each API method declares its own rate-limit policy right where the endpoint lives — no URL-matching table to keep in sync.

/** @see https://t212public-api-docs.redoc.ly/#operation/accountCash */
@retry({delayMs: 2_000})
async getAccountCash() { ... }

• Default retryable predicate matches the old axiosRetry.isRetryableError set: network errors, 429, 5xx (as SimplifiedHttpError statuses 0/429/5xx, since simplifyError runs at the interceptor level).
• Per-endpoint delays carried over 1:1 from the old table.
• getHistoryOrders now pages through the decorated getHistoryOrdersPage, preserving per-page retry semantics (a decorator on the aggregate would restart pagination) and deleting the duplicated pagination loop.

AlpacaAPI converted too (second commit): Alpaca applies one rate-limit policy across all endpoints, so a single shared retryAlpaca decorator (20 retries, linear 1s backoff) replaces the axios-retry wiring on both axios clients. shouldRetryAlpacaRequest now operates on SimplifiedHttpError instead of raw AxiosError; the PDT (40310100) and short-selling (40310000) exclusions are preserved and covered by the existing test suite (+1 new case).

Toolchain enablement:

• Dropped vestigial experimentalDecorators/emitDecoratorMetadata from tsconfig.lib.json — no legacy decorators exist in the repo, and the flag forced legacy semantics that break standard-mode decorators.
• Added a scoped pre-transform plugin to vitest.config.base.ts: oxc (rolldown-vite/Vitest 4) cannot downlevel standard decorators yet, so decorator-bearing files route through esbuild (already present via tsx). Remove once oxc ships support.

Behavior notes

• Order placement/cancel endpoints keep the old default backoff (attempt × 1s) — unchanged.
• ECONNABORTED timeouts would now retry where axios-retry excluded them; moot since neither client configures a timeout.
• axios-retry is fully removed as a dependency (third commit): the retry loop is extracted into a plain withRetry() that the decorator now adapts, and isEarningsDay — the last consumer — uses the function form with its original policy (network or 429, 3 retries, linear 1s backoff) against raw AxiosErrors, since its finnhub client skips simplifyError. Its vi.mock(.axios-retry.) workaround is gone too. (ts-retry-promise in the WebSocket managers is a different domain — left as is.)

Verified

• Typecheck: all 5 packages
• Tests: exchange 95, trading-signals 453, trading-strategies 259, messaging 84 — all green
• tsc emit + runtime smoke test of built dist/ class
• Next.js docs build (compiles exchange from source via tsconfig paths)
• eslint clean; tsx demo scripts unaffected (esbuild 0.28 downlevels standard decorators)

[bennycode]

extract RetryOptions from axios-retry

[bennycode]

this is weird, find another alternative

[bennycode]

make delay mandatory so we can see what's the retry delay directly at the function

[Copilot]

🟡 Changes recommended

The new Vitest decorators pre-transform accepts .tsx inputs but invokes esbuild with the TS (non-JSX) loader, which can break decorator-bearing TSX files.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Refactors retry behavior in the exchange package away from axios-retry interceptors toward a TC39-standard @retry decorator (and withRetry() helper), so each endpoint can declare its own retry/backoff policy without URL-based reverse mapping.

Changes:

• Added withRetry() + @retry decorator (standard decorators) and a new unit test suite for the retry utility.
• Migrated Trading212 and Alpaca API clients to decorator-based retry policies; updated related tests and simplified pagination retry semantics.
• Updated toolchain configuration to support standard decorators in Vitest and removed legacy decorator compiler flags; removed axios-retry from dependencies/lockfile.

File summaries

File	Description
vitest.shared.ts	Reuses library TS target for tests and adds a pre-transform plugin to downlevel standard decorators via esbuild.
tsconfig.lib.json	Removes legacy decorator compiler flags to avoid legacy decorator semantics.
packages/exchange/src/util/retry.ts	Introduces withRetry(), isTransientHttpError(), and the @retry method decorator.
packages/exchange/src/util/retry.test.ts	Adds tests validating retry behavior (delays, limits, non-retryables, private-field access).
packages/exchange/src/util/isEarningsDay.ts	Replaces axios-retry usage with withRetry() using an AxiosError-based predicate.
packages/exchange/src/util/isEarningsDay.test.ts	Removes axios-retry mocking no longer needed after refactor.
packages/exchange/src/broker/trading212/api/Trading212API.ts	Moves per-endpoint retry policies to @retry decorators; refactors history pagination to retry per-page.
packages/exchange/src/broker/alpaca/api/AlpacaAPI.ts	Replaces axios-retry interceptor config with a shared retryAlpaca decorator and SimplifiedHttpError-based retry predicate.
packages/exchange/src/broker/alpaca/api/AlpacaAPI.test.ts	Updates retry predicate tests to use SimplifiedHttpError; keeps post-order retry behavior assertions.
packages/exchange/package.json	Removes axios-retry dependency.
package-lock.json	Removes axios-retry and its transitive dependency from the lockfile.

Review details

• Files reviewed: 10/11 changed files
• Comments generated: 1
• Review effort level: Lite

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