Review tracker: VmFeatures stack, neo-node parse/oracle/tui

[cschuchardt88]

Review first

Do these in order. Later PRs assume earlier ones.

1. neo-vm#592 — VmFeatures on ExecutionEngineLimits. Current opcode behavior must stay identical (SafeSubStr / StrictContainerAccess / BoundedShift already in Current). Jump table stays; handlers branch on Limits.Has.
2. neo#4740 (draft) — map Echidna/Gorgon (and later forks) onto those flags in ApplicationEngine.LimitsFor. This is the neo.dll companion to Allow to ignore the recovery logs #592.
3. neo-vm#593 then neo-vm#594 — stacked on Allow to ignore the recovery logs #592. Confirm IEquatableContent and CompoundSpan are not in Current, and opcode EQUAL / CAT JSON stay unchanged.
4. neo#4741 / neo#4742 (drafts) — host-side: keep content-EQUAL and compound splice off until a hardfork.

Everything else can be reviewed in parallel after 592/4740.

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Checklist

neo-vm (merge 592 before dependents)

• neo-vm#592 VmFeatures flags for opcode hardforks
• neo-vm#593 IEquatableContent (depends on Allow to ignore the recovery logs #592)
• neo-vm#594 GetSafeSpan / ComputeSpan (depends on Allow to ignore the recovery logs #592)
• neo-vm#595 IMemoryOwner for ByteString/Buffer (independent of Allow to ignore the recovery logs #592)
• neo-vm#596 GetHashCode / ToHashCode (depends on Add isRecovering #594)
• neo-vm#597 typed ComputeSpan / 32-byte Integer (depends on Add isRecovering #594)
• neo-vm#598 neo-go reference-counter parity (independent)
• neo-vm#599 engine middleware, ILogger, debugger middleware (independent)

neo.dll (drafts until neo-vm lands)

• neo#4740 map hardforks → VmFeatures (depends on neo-vm#592)
• neo#4741 keep IEquatableContent off consensus EQUAL
• neo#4742 keep CompoundSpan off splice opcodes
• neo#4743 KeepAlive for pooled buffers that leave the VM (depends on neo-vm#595)

neo-node (master-n3, independent of each other)

• neo-node#1094 Oracle HTTPS: missing Content-Type NRE, relative redirects, Https.MaxRedirects
• neo-node#1095 getcandidates empty stack returns [] not {}
• neo-node#1096 getversion puts neo-node assembly version in existing useragent (fixes neo-node#983; no extra JSON field)
• neo-node#1097 parse / VMInstruction listing (UTF-8 comments, hashes, timestamps, blob size)
• neo-node#1099 neo-tui: plugin load, live show state, connected peers, command output popup

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Notes for reviewers

• Do not reverse the stack: neo.dll must not enable a VM feature before neo-vm ships it. Merge neo-vm#592 (and publish a CI package) before un-drafting Map hardforks onto neo-vm VmFeatures (dpends on neo-vm#592) #4740.
• Current behavior: IEquatableContent, CompoundSpan, and ContentHashCode are not in VmFeatureSets.Current. Opcode JSON tests should still match master.
• neo-node PRs target master-n3 and do not depend on the neo-vm stack.

[cschuchardt88]

Added to the tracker:

• neo-node#1099 — neo-tui (plugin load, live show state, connected peers, command popup)
• neo-node#1096 — getversion now writes the node version into existing useragent (no extra JSON field)

[roman-khimov]

What's the purpose of this? Many of these seem to be independent, some good, some more questionable. But if we're talking about stacks and multi-PR things then there should be some final goal for this changeset.

[cschuchardt88]

@roman-khimov This issue is a review tracker, not one changeset. Most of the PRs are independent. The only stack is neo-vm#592 → neo#4740 (and the type-level follow-ups that reuse Limits.Features).

Stacked goal: neo-vm is a separate package. neo.dll cannot take a dependency on ProtocolSettings inside Neo.VM, and jump-table overlays only cover opcodes. We need a way to update (or otherwise fork) neo-vm so hardfork opcode/type behavior can be selected by the host. #592 is that surface (ExecutionEngineLimits.Features). #4740 is the neo.dll map (Echidna/Gorgon → flags). After that upgrade, new VM flags should be rare — hardforks still group opcode changes in neo.dll.

Type-level PRs (neo-vm#593 IEquatableContent, #594 GetSafeSpan, #596 GetHashCode) sit on that same Features bit so they can stay off Current until a hardfork. neo#4741 / #4742 keep them off consensus until then.

Independent of the stack (review on their own):

• neo-vm#595 IMemoryOwner pooling
• neo-vm#598 neo-go reference-counter parity
• neo-vm#599 engine middleware / logger / debugger
• neo-node#1094–Create a prefix reserved for system methods #1097, Reports taking too long to be generated #1099 (N3 node bugs / neo-tui)

If you want the tracker split (one issue for the VmFeatures stack, drop the rest), that is fine — the node PRs do not depend on neo-vm.