Add comprehensive RAM billing and KV coverage tests

[heifner]

Summary

• 38 new tests covering all RAM billing code paths, iterator invalidation, cross-contract reads, and key/value boundary enforcement
• New test contract actions for parameterized billing, notification handlers, and boundary testing
• ROA limit and privileged contract bypass tests in protocol_feature_tests
• Uses key_format constexpr consistently instead of raw literals

Test Coverage

Category	Tests	What it validates
Payer change billing	4	Correct refund/charge on payer change (same size, grow, shrink, back-to-self)
Erase refund	1	Refunds stored payer, not receiver
Secondary index billing	4	Correct amounts for idx store/remove/update
Cross-account idx billing	3	Idx bills payer (not contract), refunds correctly
Read-only rejection	4	erase, idx_store/remove/update blocked (table_operation_not_permitted)
Payer auth edge cases	3	Old payer unauth ok, missing auth fails, active-only (no sysio.payer) fails
Notification billing	2	Self-pay ok, third-party blocked in notify
Mixed-payer	2	Independent deltas, net zero
ROA limit	1	Quota exceeded → ram_usage_exceeded
Privileged bypass	1	sysio.* bypasses payer auth, non-sysio.* does not
Key/value boundaries	6	Max and oversize on both create and update
Iterator invalidation	6	Primary + secondary mutation during iteration
Cross-contract reads	1	Secondary index read across contracts

[Copilot]

Pull request overview

This PR expands KV/RAM-related unit coverage by adding new contract actions and host-side tests that exercise RAM billing edge cases (payer changes, secondary index billing), iterator mutation semantics, cross-contract secondary-index reads, ROA quota enforcement, and privileged payer-authorization bypass behavior.

Changes:

• Added new test_kv_api contract actions to parameterize payer-billing scenarios, read-only rejection paths, notification-context billing, iterator invalidation under mutation, and key/value boundary cases (create + update).
• Extended kv_api_tests.cpp with comprehensive RAM billing tests (primary + secondary, cross-account), read-only transaction write rejection tests, notification billing tests, iterator mutation tests, and cross-contract read tests.
• Added protocol feature tests for ROA RAM ceiling enforcement via KV paths and for privileged sysio.* payer-authorization bypass behavior.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 3 comments.

File	Description
unittests/test-contracts/test_kv_api/test_kv_api.cpp	Adds new test actions for boundary enforcement, payer-parameterized billing, read-only rejection, notification billing, iterator mutation, and cross-contract reads; updates callers to use key_format.
unittests/test-contracts/test_kv_api/test_kv_api.abi	Updates ABI to include the newly added test_kv_api actions/structs used by host-side tests.
unittests/protocol_feature_tests.cpp	Adds ROA-limit enforcement test for KV paths and privileged payer-auth bypass tests for sysio.* vs non-sysio.* privileged contracts.
unittests/kv_api_tests.cpp	Adds host-side Boost tests covering KV RAM billing, payer changes, secondary index billing, read-only rejection, notification billing, iterator mutation, and cross-contract reads.

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[Copilot]

tstmaxkeyupd declares uint32_t actual but never uses it, which can trigger -Wunused-variable (and potentially fail builds when warnings are treated as errors). Remove the variable, or use it (e.g., by switching to an API that returns an actual-size outparam if intended).

Suggested change

	char buf[4]; uint32_t actual = 0;
	char buf[4];

[heifner]

c906a7a

[Copilot]

ramnotify doesn't use key_id or val_size, which can trigger -Wunused-parameter warnings in contract builds. Consider marking them [[maybe_unused]] or explicitly casting to void to keep builds warning-clean while still keeping the parameters in the action data for the notification handler.

Suggested change

	void ramnotify(uint32_t key_id, uint32_t val_size) {
	void ramnotify([[maybe_unused]] uint32_t key_id, [[maybe_unused]] uint32_t val_size) {

[heifner]

c906a7a

[Copilot]

ramnotiferr doesn't use its parameters (key_id, val_size, payer), which can trigger -Wunused-parameter warnings in contract builds. Mark unused parameters [[maybe_unused]] or cast them to void so warnings don’t become errors under stricter build settings.

Suggested change

	void ramnotiferr(uint32_t key_id, uint32_t val_size, sysio::name payer) {
	void ramnotiferr(uint32_t key_id, uint32_t val_size, sysio::name payer) {
	(void)key_id;
	(void)val_size;
	(void)payer;

[heifner]

c906a7a