refactor(ruby): idiomatic pass (Shopify Ruby + rubystyle)

[EfeDurmaz16]

Idiomatic-Ruby pass over the Ruby SDK MPP verifier (Shopify Ruby Style Guide + rubystyle.guide + the pay-kit Ruby review overlay). Behavior-preserving — reject strings and verifier checks are unchanged; verified by the full suite.

Stacked on #222 (fix(ruby): ...): base is fix/ruby-security-hardening so this PR shows only the idiomatic delta; it re-targets #219 once #222 merges. This is the refactor(<lang>) half of the per-language work.

• mpp/protocol/solana/verifier.rb: explicit program tables (TOKEN_PROGRAMS / ALLOWED_PAYMENT_PROGRAMS), three keyword_init Struct value objects (TransferExpectation / SplTransferExpectation / AtaCreationPolicy), and keyword / value-object flow over long positional helper calls.

Scoped strictly to structural refactoring: the earlier solana.rb rescue narrowing was reverted after review (a behavior change belongs in a fix(ruby), not a refactor), so the diff is a single file.

Verified: bundle exec rake test → 465 runs, 0 failures; standardrb clean.

[greptile-apps]

Greptile Summary

This PR is a behavior-preserving idiomatic Ruby refactor of verifier.rb, stacked on the security-hardening base branch. No logic changes are introduced — all existing verification paths, error messages, and rejection conditions are unchanged.

• Extracts two frozen constant arrays (TOKEN_PROGRAMS, ALLOWED_PAYMENT_PROGRAMS) to replace inline anonymous arrays that were re-allocated on every call.
• Introduces three keyword_init: true Struct value objects (TransferExpectation, SplTransferExpectation, AtaCreationPolicy) to replace long positional argument lists.
• Adds sol_transfer_expectations and spl_transfer_expectations factory helpers that collapse two call sites into a single uniform each loop.

Confidence Score: 5/5

Safe to merge — every verification path, rejection condition, and error message is unchanged from the base branch.

The diff is a single file, purely structural: frozen constant arrays replace inline anonymous arrays, three keyword_init Structs replace positional argument lists, and two factory helpers unify call sites. No conditional logic, guard clause, or error-path was added, removed, or reordered in a security-relevant way. The 465-test suite passes cleanly.

No files require special attention.

Important Files Changed

Filename	Overview
ruby/lib/pay_kit/protocols/mpp/protocol/solana/verifier.rb	Idiomatic Ruby refactor: frozen constant arrays, three keyword_init Struct value objects, and factory helpers replace positional arg lists; logic is unchanged and test suite confirms parity.

_{Reviews (4): Last reviewed commit: "refactor(ruby): idiomatic pass (Shopify ..." | Re-trigger Greptile}

[greptile-apps]

Explicit rescue list may miss network-level exceptions

The new rescue clause covers RpcError, RuntimeError, KeyError, JSON::ParserError, and TypeError, but Ruby's Errno::* family (e.g., Errno::ECONNREFUSED, Errno::ETIMEDOUT), Net::ReadTimeout, SocketError, and OpenSSL::SSL::SSLError are all StandardError subclasses that are not subclasses of RuntimeError. If ::PayCore::Solana::Rpc::RpcError does not wrap every low-level transport failure, those exceptions will now escape this block and surface as unhandled 500s instead of the clean Mpp::Error translation that the old bare rescue guaranteed. Please verify that RpcError wraps all failure modes of rpc.account_owner, or widen the list with the additional transport-layer exception classes.

[EfeDurmaz16]

Addressed the 4/5 review: reverted the solana.rb rescue narrowing (a behavior change doesn't belong in a refactor, and RpcError's rpc_error_class hook means transport-error wrapping isn't guaranteed for every rpc instance). The PR is now a single-file, purely structural verifier.rb refactor — the part the review already rated clean. 465 tests green, standardrb clean. @greptile-apps please review

[EfeDurmaz16]

Re-review is clean on cb392c3 (the earlier 4/5 note was the solana.rb rescue narrowing, now reverted — this PR is a single-file, purely structural verifier.rb refactor). Ready alongside #222. @lgalabru

[EfeDurmaz16]

@greptile-apps please review