refactor!: remove deprecated handle_message from AntProtocol

[mickvandijke]

Summary

• Removes the deprecated handle_message method from AntProtocol, which always returned response bytes even for response messages, risking infinite ping-pong loops
• Migrates all 22 call sites (unit tests, e2e tests, message handler loop) to try_handle_request, which returns Option<Bytes> (None for response messages)
• Updates test_handle_unexpected_response_message to assert None instead of an error response

Test plan

• All 272 unit tests pass (cargo test)
• All 14 handler-specific tests pass (cargo test --lib storage::handler)
• cargo fmt clean
• No new clippy warnings introduced

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR removes the deprecated AntProtocol::handle_message API and standardizes all protocol handling call sites on try_handle_request, which returns None for response messages to avoid reply ping-pong loops.

Changes:

• Remove deprecated handle_message from AntProtocol and rely on try_handle_request: Result<Option<Bytes>>.
• Update E2E protocol call sites to unwrap Option<Bytes> and avoid replying to response messages.
• Adjust a handler test to assert None for unexpected response message inputs.

Reviewed changes

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

File	Description
tests/e2e/testnet.rs	Switch local protocol handling and P2P message routing to try_handle_request, replying only on Some(response)
tests/e2e/security_attacks.rs	Update direct protocol PUT helper to unwrap Option and require a response
tests/e2e/data_types/chunk.rs	Update E2E chunk payment enforcement test flows to unwrap Option responses
src/storage/handler.rs	Remove deprecated handle_message, update tests to use try_handle_request, and adjust unexpected-response behavior

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[Copilot]

The top-level architecture diagram still implies try_handle_request “return Ok(response_bytes)”, but the method now returns Result<Option<Bytes>> and may return Ok(None) for response messages. Please update the diagram text to reflect the Option return (e.g., Ok(Some(response_bytes)) / Ok(None)), so it doesn’t mislead readers.

[Copilot]

The new ok_or_else(|| TestnetError::Storage("expected response".to_string()))? error message is very generic and will make E2E failures harder to diagnose. Consider including context (e.g., request_id, message type, and/or that the protocol returned None which likely indicates an unexpected response message).

Suggested change

	.ok_or_else(|| TestnetError::Storage("expected response".to_string()))?;
	.ok_or_else(|| {
	TestnetError::Storage(format!(
	"Protocol returned no response bytes for PUT request (request_id={request_id}, node_index={})",
	self.index
	))
	})?;

[Copilot]

Same as store_chunk: the new "expected response" error is very generic for debugging E2E failures. Consider adding context (e.g., request_id/address being fetched and that try_handle_request returned None).

Suggested change

	.ok_or_else(|| TestnetError::Retrieval("expected response".to_string()))?;
	.ok_or_else(|| {
	TestnetError::Retrieval(format!(
	"expected response from try_handle_request for GET chunk {address:?} \
	with request_id {request_id}, but got None"
	))
	})?;