What

Re-enables ProxyType::RootWeights with a deliberately minimal scope: a RootWeights proxy can dispatch SubtensorModule::set_root_weights and nothing else.

Why

The variant (SCALE index 12) was neutralized when proxy filters moved to deny-by-default allowlists: proxy.add_proxy(delegate, RootWeights, 0) still succeeds and the delegation shows up in Proxy.Proxies, but every subsequent proxy.proxy(...) is filtered. The grant looks placed yet does nothing — the worst of both worlds. With root reborn (#2968) making per-coldkey root weights meaningful again, delegating exactly that call to a low-value operational key (keeping the coldkey offline) is a real use case.

Changes

• runtime/src/proxy_filters/call_groups.rs — new RootWeightCalls group containing only SubtensorModule::set_root_weights. It lives with the proxy-specific groups and overlaps SubtensorCommonCalls (the same way SmallTransferCalls overlaps BalanceTransferCalls) rather than granting that whole group: the validator's consensus-weight surface (set_weights, batch/commit/reveal) stays out of reach — that is precisely what this proxy type must not delegate.
• runtime/src/proxy_filters/mod.rs — RootWeights maps to RootWeightCalls in both the executable filter (proxy_type_filter) and the runtime-API metadata (proxy_filter_mode); both derive from the same group, so they cannot drift.
• is_superset — NonTransfer ⊃ RootWeights already held. Added NonFungible ⊃ RootWeights: NonFungible already allows set_root_weights itself (via SubtensorCommonCalls), so it would be incoherent for a NonFungible proxy to be unable to manage a delegation that is a strict subset of its own rights. (is_superset gates a proxy adding/removing other delegations through proxy.proxy.)
• common/src/proxy.rs — RootWeights no longer reports is_deprecated(), so the runtime API's deprecated flag follows. Variant order is untouched: index 12 stays 12 and existing on-chain delegations keep their type.
• SDK/docs — add_proxy / create_pure help text no longer lists RootWeights among the deny-all types; docs reference pages regenerated from the registries.

spec_version bumped 441 → 442: mainnet already runs 441 (root-reborn deployed), and the runtime-checks spec-version gate requires runtime-affecting PRs to carry a spec newer than mainnet unless labeled no-spec-version-bump (which is for changes deliberately shipping without a runtime release — not this one).

Existing on-chain grants

This change retroactively activates RootWeights delegations registered while the type was inert. Scan of Proxy.Proxies on finney at finalized block 8,765,950 (2026-08-03): 7,758 delegations across 6,722 delegator accounts — exactly one of type RootWeights:

Two options were weighed:

1. Accept the existing grant (chosen). The right that activates is exactly what the type's name promises — add_proxy(RootWeights) had no other plausible intent — and the delegator can revoke at any time with remove_proxy. A one-shot purge migration to strip a single row adds more code and upgrade risk than the retroactive grant it would remove.
2. Ship a storage migration purging pre-activation RootWeights entries. Rejected for the reason above; if reviewers prefer it, the affected entry is the single row listed here.

Additional mitigation: set_root_weights itself is still globally gated by RootWeightSettingEnabled (default off — it fails with RootWeightSettingDisabled until governance flips it via AdminUtils::sudo_set_root_weight_setting_enabled). The pre-existing delegation therefore cannot dispatch anything until that flag is enabled, leaving a clear window to revoke.

Tests

• root_weights_grants_exactly_set_root_weights (new) — the filter accepts set_root_weights; rejects set_weights, add_stake, remove_stake, swap_hotkey, set_children; the metadata view exposes exactly one call.
• narrow_proxies_have_exact_allow_lists — now pins allowed_calls(RootWeights) == {SubtensorModule::set_root_weights}.
• non_fungible_superset_is_explicit_allowlist (new) — pins NonFungible's superset set to {NonFungible, RootWeights}, mirroring the existing NonTransfer pin.
• any_allows_everything_and_deprecated_allow_nothing — RootWeights removed from the deny-all list (Triumvirate / Senate / Governance remain pinned there).
• The pre-existing superset_relations_match_allowed_call_sets and all_call_groups_cover_runtime_call_metadata invariants cover the new superset edge and the group inventory (no duplicate in AllCalls).

Verification

• SKIP_WASM_BUILD=1 cargo test -p node-subtensor-runtime -p subtensor-runtime-common — green (25 proxy tests, full crate suites).
• cargo clippy (runtime + common, with tests) and cargo fmt — clean.
• SDK: ruff, proxy pytest subset (34 passed), and the docs staleness check (generate.py --check) — green.