feat(tempo): offer OUSD first in server currency defaults

[decofe]

Motivation

Offer OUSD first with USDC.e on mainnet and pathUSD on Moderato, while keeping gas-token selection independent of the payment currency.

Summary

• Add ordered tempo(currencies=...), TempoMethod.currencies, OUSD, and default_currencies_for_chain().
• Expand default server charge/compose responses into one challenge per accepted currency.
• Add local sponsor fee_token and allowed_fee_tokens; select balances sufficient for the gas budget. Unsponsored OUSD payments also select a funded supported gas token.

Public interface migration:

# Before: one accepted token.
method = tempo(intents={"charge": ChargeIntent()}, recipient=recipient, currency=USDC)

# After: ordered offers; omit currencies for network defaults.
method = tempo(
    intents={"charge": ChargeIntent()},
    recipient=recipient,
    currencies=[OUSD, USDC],
)

# An unpaid multi-currency response is ComposedChallenges, not Challenge.
result = await server.charge(None, "0.10")
offers = result.challenges if isinstance(result, ComposedChallenges) else [result]

Key design considerations

• currency= remains supported but deprecated for servers; a per-request currency override still produces one Challenge. Consumers must handle ComposedChallenges when multiple currencies are accepted.
• Explicit lists replace defaults; invalid/empty lists and simultaneous singular/plural configuration are rejected. Deduplication preserves order.
• fee_token requires a local fee_payer and must satisfy its allowlist. Default gas tokens are pathUSD then USDC.e on mainnet, pathUSD on Moderato; OUSD is not implicitly allowed for gas.
• Explicit client currency selection remains available; default offer ordering does not imply balance-aware payment selection or swaps. Stripe's Tempo rail retains its single supported deposit currency.

[brendanjryan]

@codex review

[chatgpt-codex-connector]

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-30T00:04:31.700154Z	361470e	Manual request

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[chatgpt-codex-connector]

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Reviewed commit: 361470ea0a

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[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	pypi/​pyjwt@​2.13.0 ⏵ 2.15.1	+1	+75

View full report