Solution: LP-0013 — Token program authorities

[ego-errante]

Solution: LP-0013 — Token program authorities

Submitted by: ego-errante

Summary

This solution adds a rotatable mint authority model to the LEZ Token program. The implementation is built around lez-approval — a new agnostic single-admin approval crate that fulfils RFP-001 — and exposes four new instructions (NewFungibleDefinitionWithAuthority, MintWithAuthority, RotateAuthority, RevokeAuthority) layered additively over the existing Token surface. Revocation is terminal (Authority::renounced() is a permanent sentinel), so fixed-supply tokens are expressible as "mint everything, then revoke."

Repository

• Repo: https://github.com/ego-errante/logos-execution-zone
• Branch: lp-0013-token-authorities
• Commit: 47040d14
• Key files:
  • lez-approval/src/lib.rs — RFP-001 agnostic approval library (Authority, ApprovalError)
  • programs/token/core/src/lib.rs — Instruction enum extensions and the canonical Authority field on TokenDefinition::Fungible
  • programs/token/src/{new_definition,mint,rotate}.rs — handler implementations
  • program_methods/guest/src/bin/token.rs — guest dispatcher
  • wallet/src/{program_facades,cli/programs}/token.rs — wallet facade + CLI subcommands
  • examples/{fixed-supply,variable-supply}/ — two example integrations
  • integration_tests/tests/token_authority.rs — end-to-end lifecycle tests
  • artifacts/token.idl.spel.json — SPEL-emitted IDL (provenance, generated from spel-sidecar/)
  • artifacts/token.idl.json — hand-authored canonical IDL (completeness, conforms to SpelIdl)
  • spel-sidecar/ — sidecar Cargo package outside the workspace that hosts the SPEL-shape mirror
  • docs/SPEL_STATUS.md — disclosure of the IDL story (why a sidecar, the scaffold↔real mapping)
  • demo.sh — clean-checkout end-to-end demo (rotate / revoke flow ends with balance 1500)

Approach

Architecture

The Token program already had Mint, Transfer, NewFungibleDefinition, etc. as variants of a single Instruction enum dispatched by program_methods/guest/src/bin/token.rs. I layer the authority model additively: four new instruction variants (NewFungibleDefinitionWithAuthority, MintWithAuthority, RotateAuthority, RevokeAuthority) coexist with the existing surface. The pre-existing Mint and NewFungibleDefinition paths are untouched, so naïve callers continue to work and the new variants are entirely opt-in for callers that want the gated lifecycle.

State-wise, the authority is recorded as a single new authority: Authority field on TokenDefinition::Fungible. I chose to store the authority on the definition rather than in a separate PDA (the Solana SPL pattern) because LEZ's per-account model already gives me atomic read-modify-write semantics within a single transaction — there is no concurrency benefit to splitting the field out, and a separate PDA would double the account count of every authority-gated instruction. The trade-off is that the authority field is a breaking Borsh-layout change for pre-existing TokenDefinition::Fungible accounts. This is acceptable today (LEZ does not promise in-flight schema-compatibility across upgrades), but the TokenDefinition doc comment in programs/token/core/src/lib.rs sketches FungibleV2 and separate-PDA alternatives as deferred options for if LEZ ever does.

lez-approval as the RFP-001 deliverable

The agnostic approval library is implemented as a new top-level workspace crate, lez-approval. It exposes:

• Authority(Option<AccountId>) — a single-admin wrapper whose None state is terminal (the renounced sentinel). The Option is intentionally hidden behind constructor (Authority::new, Authority::renounced) and predicate (Authority::is_renounced) methods so callers cannot accidentally reach into the None state via pattern matching and revive a renounced authority.
• ApprovalError { Unauthorized, Renounced } — the two-variant error type that the panic-on-failure semantics surface as panic payloads. Unauthorized covers both "the wrong signer" and "the signer is not authorized at all"; Renounced covers all post-revocation rejections.
• A gate / rotate / revoke contract that the Token program calls through.

LEZ guest programs panic on failure (the prover catches the panic and rejects the transaction), so I follow the same convention: every authorization failure panics with an ApprovalError payload rather than returning a Result. This matches the surrounding code and avoids each handler having to write match … panic!() boilerplate. The library is generic — it depends only on nssa_core::account::AccountId and could be reused verbatim by any other LEZ program that wants single-admin gating (e.g. a freeze authority on the same Token program, or a config authority on a future on-chain module).

Why the Logos stack

The single-admin authority model only earns its keep when the underlying execution layer makes it cheaply enforceable, atomic, and observably correct.

• Trustless execution. Because every state transition is proved in a RISC0 guest, a renounced authority is provably renounced — there is no off-chain admin key that someone could secretly retain to revive it. On a centralised alternative the "revoked" state would always be a social commitment; on LEZ it is a circuit-enforced invariant.
• Censorship resistance. Authority rotation is just another transaction in the LEZ mempool; the sequencer cannot selectively reject it without dropping the whole block. A centralised token-issuance API could refuse rotation requests from blocked accounts.
• Atomicity at the right grain. The post-state of rotate_authority either updates the definition account's authority field or panics; there is no intermediate state where the authority is None but the new admin is not yet recorded. LEZ's per-account read-modify-write semantics give me this for free, which is why I did not need a two-phase commit pattern.

A centralised token-issuance backend could replicate the API surface, but it could not give a wallet a proof that a token's mint authority has been provably revoked. That is the property the Logos stack uniquely enables for this use case.

Alternatives considered

• Separate authority PDA (Solana SPL pattern). Rejected for cost (doubles per-transaction account count) and complexity (no concurrency benefit on LEZ). Documented as a future option in TokenDefinition's doc comment if LEZ ever introduces in-flight Borsh-schema compatibility guarantees.
• Result-returning handlers instead of panic-on-failure. Rejected for consistency with the surrounding LEZ guest convention — every other handler in the Token program panics on failure. Mixing return styles would be a maintenance trap.
• In-place mutation of Instruction::Mint to add an optional authority argument. Rejected as a breaking change to the wire format that would have invalidated every existing caller. Additive variants are the correct LEZ idiom for this kind of evolution.
• #[lez_program] directly on program_methods/guest/src/bin/token.rs to get a real-program SPEL IDL. Attempted and abandoned — pulling spel-framework into the workspace causes a hard nssa_core v0.1.0 vs v0.2.0-rc3 dep-graph collision (#[lez_program] proc-macro emits path-literal references to whichever nssa_core cargo picked for the macro-invoking crate; one universe per macro invocation). The [patch]-to-local-path workaround is a coin flip due to feature-flag and API drift. Full disclosure in docs/SPEL_STATUS.md. I instead ship the IDL via a sidecar scaffold (spel-sidecar/) that runs SPEL out-of-workspace, plus a hand-authored canonical IDL — matching the bar set by the prior community submission (PR #57).

Success Criteria Checklist

Functionality

• Variable-size Tokens through minting authority — NewFungibleDefinitionWithAuthority sets the initial authority at definition creation; MintWithAuthority mints gated by the recorded authority; RotateAuthority and RevokeAuthority cover rotation and terminal revocation (renounced state is a permanent sentinel via Authority::renounced()).
• Two example integrations — examples/fixed-supply/ (mint everything, then revoke) and examples/variable-supply/ (rotatable inflation), both runnable end-to-end.
• Self-sufficient, agnostic library per RFP-001 — lez-approval/ ships Authority, ApprovalError, and the gate / rotate / revoke primitives. The crate depends only on nssa_core::account::AccountId and is reusable by any LEZ program that wants single-admin gating.

Usability

• Module/SDK for Logos modules — wallet/src/program_facades/token.rs exposes typed builders for the four new instructions; wallet/src/cli/programs/token.rs wires them as CLI subcommands. demo.sh exercises both surfaces end-to-end.
• IDL for the updated Token program — Two artifacts: artifacts/token.idl.spel.json (SPEL-emitted via spel generate-idl against the spel-sidecar/ sidecar — provenance) and artifacts/token.idl.json (hand-authored against the SpelIdl schema — completeness, including the errors table for ApprovalError::{Unauthorized, Renounced} which the v0.4.0 CLI does not yet emit). See docs/SPEL_STATUS.md for the workaround rationale and reproducibility steps.

Reliability

• Atomic rotation/revocation — Both handlers either return updated post-states or panic. The Authority state machine has no intermediate state: rotate is a single field write to authority: Authority::new(new_admin), and revoke is a single field write to authority: Authority::renounced(). Covered by integration tests rotate_then_mint_succeeds and revoke_after_authority_set_succeeds (both in integration_tests/tests/token_authority.rs).
• Deterministic revoked-mint rejection — MintWithAuthority against a renounced definition panics with ApprovalError::Renounced, a documented error variant in lez-approval/src/lib.rs. Covered by integration test mint_after_revoke_panics. The panic-on-failure path is the canonical LEZ guest rejection mechanism.

Performance

• Compute unit (CU) cost documentation — LEZ has no Solana-style per-instruction CU metric; the RISC0-native proxy is user-cycle count from risc0_zkvm::default_executor. Cycle counts captured for all three new instructions via integration_tests/src/bin/cycle_executor.rs and documented in docs/CYCLE_COSTS.md (raw measurement log) and README.md (summary table with caveats). Numbers on the committed artifacts/program_methods/token.bin: MintWithAuthority 154 858 cycles, RotateAuthority 127 350 cycles, RevokeAuthority 103 913 cycles (all single-segment, 2^18 padded).

Supportability

• Deployed and tested on standalone sequencer — demo.sh runs the full lifecycle against a docker-compose-spun standalone LEZ sequencer.
• End-to-end integration tests in CI — integration_tests/tests/token_authority.rs (five test cases) runs under cargo nextest against the standalone sequencer harness. Validated locally with cargo nextest run -p integration_tests --test token_authority -j 1 (5/5 PASS).
• CI green on default branch — All 9 GitHub Actions jobs green on lp-0013-token-authorities at 47040d14: run #26419209365.
• README end-to-end usage — README.md "LP-0013 — Token program: rotatable mint authority" section now covers: standalone deployment (demo.sh + manual standalone-sequencer steps), copy-pasteable CLI walkthrough for new-fungible-with-authority / mint-with-authority / rotate-authority / revoke-authority, cycle cost table (linked to docs/CYCLE_COSTS.md), ApprovalError::{Unauthorized, Renounced} panic-payload table, two-IDL pointer (linked to docs/SPEL_STATUS.md), and explicit limitations / follow-ups.
• Reproducible demo with RISC0_DEV_MODE=0 — demo.sh runs the full mint → transfer → rotate → revoke → mint-fails sequence with RISC0_DEV_MODE=0 and a clean docker-compose state. End-state holder balance is 1500 after the rotated-admin mints 500 onto an initial 1000 mint.
• Narrated video walkthrough — Pending Day 6 (final-mile work before flipping Draft → Ready).

FURPS Self-Assessment

Functionality

Three new instruction variants (MintWithAuthority, RotateAuthority, RevokeAuthority) plus the authority-aware definition constructor NewFungibleDefinitionWithAuthority. Pre-existing Mint, Transfer, NewFungibleDefinition, InitializeAccount, Burn, PrintNft, and NewDefinitionWithMetadata are unchanged. The authority model supports the three Solana-style patterns: fixed supply (mint then revoke), variable supply (active authority), and authority handoff (rotate). The renounced state is terminal — once revoked, no instruction can re-introduce an authority on that definition.

Limitation: the authority lives only on TokenDefinition::Fungible (not on the non-fungible variant). The non-fungible path was out of scope for this prize.

Usability

Wallet integration exposes typed program_facades/token.rs builders and CLI subcommands for mint-with-authority, rotate-authority, and revoke-authority. The CLI mirrors the existing Token-program subcommand idiom; no new flags or env vars beyond the existing wallet setup are required.

The IDL story is the most reviewer-visible Usability tradeoff. Quoting docs/SPEL_STATUS.md:

This solution ships two IDL files at artifacts/:

• artifacts/token.idl.spel.json — spel generate-idl (real SPEL toolchain, v0.4.0) — Provenance — proves the program shape parses through SPEL's macro grammar
• artifacts/token.idl.json — hand-authored against the SpelIdl schema in spel-framework-core — Completeness — includes shapes the v0.4.0 CLI does not yet emit (e.g. the errors table for ApprovalError::{Unauthorized, Renounced})

The straightforward path — annotate program_methods/guest/src/bin/token.rs directly with #[spel_framework::lez_program], depend on spel-framework from the workspace, and let the macro emit the IDL during the normal guest build — does not compile in this checkout. The reason is a dep-graph collision between two versions of the same crate, plus a downstream cross-compile failure that the collision makes structurally difficult to fix.

Reviewers can reproduce the SPEL-emitted IDL via:

cargo install --git https://github.com/logos-co/spel --tag v0.4.0 spel
spel -- generate-idl spel-sidecar > artifacts/token.idl.spel.json

Reliability

The single-admin state machine has three states (Some(admin), transitioning Some(admin) → Some(new_admin) via rotate, and the terminal None via revoke) with no intermediate or unreachable states. The panic-on-failure semantics inherited from the LEZ guest convention mean every authorization failure is an unrecoverable rejection that the prover catches; there is no path to a partially-rotated or partially-revoked state. The five integration tests in integration_tests/tests/token_authority.rs cover: mint-with-active-authority, mint-by-wrong-signer-panics, rotate-then-new-admin-mints, revoke-then-mint-panics, and rotate-after-revoke-panics.

Performance

The three gated new instructions each add an is_authorized check and one AccountId equality check on top of the baseline Mint's arithmetic. Measured user-cycle counts on the committed artifacts/program_methods/token.bin (single-segment, 2^18 padded): MintWithAuthority 154 858, RotateAuthority 127 350, RevokeAuthority 103 913. Raw measurement log in docs/CYCLE_COSTS.md; summary table in the README.

Supportability

• Test coverage: Unit tests in programs/token/src/tests.rs cover the Authority state machine transitions and the gate / rotate / revoke primitives in isolation (8 tests across the rotate / revoke / mint-with-authority paths). Integration tests in integration_tests/tests/token_authority.rs cover the end-to-end lifecycle against a real standalone sequencer (5 tests).
• CI: Existing cargo nextest harness; new test file slots into the existing integration-test workflow without additional configuration.
• Deployment: demo.sh is the canonical end-to-end deployment + exercise script. Reviewers can run it from a clean checkout with RISC0_DEV_MODE=0 ./demo.sh.
• Code structure: Authority logic is split between the agnostic lez-approval/ crate (reusable) and the Token-program-specific handlers in programs/token/src/{new_definition,mint,rotate}.rs. The lez-approval boundary makes the same pattern reusable for any future LEZ program that wants single-admin gating.

Supporting Materials

• Companion repo: https://github.com/ego-errante/logos-execution-zone/tree/lp-0013-token-authorities
• SPEL IDL disclosure: docs/SPEL_STATUS.md
• Sidecar scaffold: spel-sidecar/
• Demo script: demo.sh
• Narrated video: pending Day 6

Terms & Conditions

By submitting this solution, I confirm that I have read and agree to the Terms & Conditions.

[github-actions]

✅ Validation passed

A reviewer will assess against the prize criteria.
ℹ️ Solution submission for LP-0013.
ℹ️ Checking repo: https://github.com/ego-errante/logos-execution-zone

---

Automated check. See solution template and TERMS.

[ego-errante]

Day-5 polish landed (HEAD 9e222602 on ego-errante/logos-execution-zone:lp-0013-token-authorities):

• Compute unit / cycle cost documentation — integration_tests/src/bin/cycle_executor.rs captures risc0_zkvm::default_executor cycle counts for all three new instructions. Summary table in README.md; raw measurement log in docs/CYCLE_COSTS.md (date, machine, ELF sha256, repo HEAD pinned for reproducibility). Numbers: MintWithAuthority 154 858 cycles, RotateAuthority 127 350 cycles, RevokeAuthority 103 913 cycles (single-segment, 2^18 padded).
• README end-to-end usage — LP-0013 section now covers standalone deployment, copy-pasteable CLI walkthrough for all four LP-0013 commands, the cycle table, ApprovalError::{Unauthorized, Renounced} panic-payload table, two-IDL pointer to docs/SPEL_STATUS.md, and explicit limitations.
• Local CI sanity — cargo +nightly fmt --check and cargo clippy --all-targets -- -D warnings clean across the LP-0013 surface (lez-approval, programs/token, wallet/cli, examples/{fixed,variable}-supply, integration_tests).
• Validator note — Repo default branch on the fork has been moved to lp-0013-token-authorities so the lambda-prize validator can see demo.sh and artifacts/token.idl{,.spel}.json at the repo root.

Ready for review pending the narrated video walkthrough (Day 6 — required to flip Draft → Ready per the prize spec). All other success criteria are addressed and the corresponding checkboxes in solutions/LP-0013.md have been ticked.

[mart1n-xyz]

Appreciate your work towards a Lambda prize. In terms of housekeeping, we close all PRs in draft mode. Please do a PR only with a complete solution. Thank you.

[ego-errante]

Noted @mart1n-xyz ! opening a new one soon