[matthewwalsh0]

Explanation

The max-amount quote flow (atomic-first max quotes, subsidized promotion, and the gas station re-quote) lives in RelayStrategy and reads Relay's quote shape directly, so it can't be reused by ServerStrategy.

This moves it into provider-agnostic utilities, with no behaviour change:

• utils/max-quote.ts: getMaxQuotes runs the max flow (atomic first when supported, otherwise non-atomic with subsidized promotion, including the MFA keyring guard from fix(transaction-pay-controller): keep max quotes non-atomic for MFA keyrings #11389). Also exports isAtomicMaxSupported and isAtomicMaxQuote.
• utils/max-gas-station.ts: getMaxGasStationQuote runs the probe → adjusted quote flow with the configurable cost buffer from feat(transaction-pay-controller): add buffer to max gas station cost #11434.
• Strategy callbacks: each strategy supplies getQuoteDetails (gas limits, gas station transactions, gasless, subsidized, target amount), getQuotes, requote and validateAtomicQuote, so the shared code never reads a strategy's original quote.
• RelayStrategy now calls getMaxQuotes; relay-max.ts is removed, along with the unused isMaxGasStation metadata tag and ATOMIC_PROMOTION_FAILURE_PREFIX constant.

ServerStrategy adoption follows separately in #11418.

References

• Builds on feat(transaction-pay-controller): add buffer to max gas station cost #11434.
• Followed by feat(transaction-pay-controller): support max quotes in server strategy #11418.

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Medium Risk
Refactors max-amount and gas-station quoting on payment-critical paths; behavior is intended to be unchanged but regression risk is moderate given removed Relay-only implementation and new shared routing.

Overview
Moves Relay-specific max-amount quoting into shared utils/max-quote and utils/max-gas-station, and wires Relay through strategy callbacks instead of relay-max.ts.

The deleted relay-max module (and its large test file) is replaced by getMaxQuotes (atomic-first vs promoted subsidized routes, MFA guard, atomic validation errors) and getMaxGasStationQuote (probe → adjusted re-quote with gas buffer). Relay now implements getRelayMaxQuoteDetails and passes getQuotes / requote / validateAtomicQuote into the shared flow. Quote validation skips quotes already handled as atomic max via isAtomicMaxQuote, and max call embedding uses isAtomicMaxSupported instead of inline feature-flag checks.

Cleanup and tests: ATOMIC_PROMOTION_FAILURE_PREFIX moves into max-quote.ts; isMaxGasStation metadata and related oxlint suppressions are removed. New unit suites cover the shared max and gas-station paths; Relay gains a gasless max quote test and a submit test rename (source gas fee token vs max-gas-station). GasStationStepData is exported for reuse across strategies.

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