Propagate proxy inner post-dispatch weight

[UnArbosSix]

Summary

Fix proxy calls failing to refund unused inner-call weight.

Both Proxy::proxy and Proxy::proxy_announced declared the inner call's worst-case weight but returned a plain DispatchResult. Although the inner dispatch populated post_info.actual_weight, do_proxy discarded it after recording the result.

This caused transaction payment to charge the full declared weight for proxied calls, even when the inner call reported lower actual weight.

Changes

• Return DispatchResultWithPostInfo from proxy and proxy_announced.
• Extract the inner call's actual weight with extract_actual_weight.
• Return the proxy overhead plus the inner actual weight.
• Preserve existing LastCallResult and ProxyExecuted behavior.
• Add regression tests for both proxy paths.

Validation

• All 28 pallet-subtensor-proxy tests pass.
• Proxy no_std check passes.
• Native runtime check passes.
• Live three-node localnet assertion passes:
  • Declared weight: 2,664,017,457
  • Actual weight: 735,182,257
  • Worst-case quoted fee: 1,386,563 rao
  • Actual charged fee: 368,067 rao
  • Refunded: 1,018,496 rao
• The fee payer's balance delta exactly matched the emitted TransactionFeePaid.actual_fee.

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Project	Deployment	Actions	Updated (UTC)
subtensor	Ready	Preview	Aug 7, 2026 7:57pm

[github-actions]

🛡️ AI Review — Skeptic (security review)

VERDICT: VULNERABLE

HIGH scrutiny: account is under 90 days old with no public repositories, mitigated by repository write permission and substantive merged contributions; fix/proxy-post-dispatch-weight-refund targets main.

Findings

Sev	File	Finding
HIGH	runtime/src/lib.rs	Bump the runtime spec version	(off-diff)

Other findings

• [HIGH] Bump the runtime spec version (runtime/src/lib.rs) — This pallet is part of the runtime, and the PR changes proxy and proxy_announced post-dispatch weight behavior. Leaving runtime/src/lib.rs at spec_version: 443 allows nodes whose different native runtime also reports version 443 to execute different fee/weight logic than the newly deployed Wasm runtime, risking consensus divergence. Increment spec_version for this runtime-affecting change.

Conclusion

The weight-refund implementation appears sound, but changing runtime dispatch behavior without incrementing spec_version can cause native/Wasm runtime divergence. The version must be bumped before merge.

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# 🔍 AI Review — Auditor (domain review) has not yet run on this PR.

[github-actions]

🔄 AI review updated — Skeptic: VULNERABLE