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+# Solution: LP-0013 — Token Program Improvements: Authorities
+
+**Submitted by:** bristinWild
+
+## Summary
+
+This submission implements a complete mint authority model for the LEZ Token program. Fungible tokens can now be created with a designated mint authority that can mint additional supply, rotate control to a new key, or permanently revoke minting to fix the supply. A standalone `lez-authority` crate provides the reusable authority primitive as defined in RFP-001.
+
+## Demo Video
+Link - https://www.youtube.com/watch?v=fJWbhobNIFM
+
+## Repository
+
+- **Repo:** https://github.com/bristinWild/logos-execution-zone
+- **Branch:** `main`
+- **Commit:** `da61c4fb`
+- **Key files:**
+  - `lez-authority/src/lib.rs` — agnostic `AuthoritySlot` library (RFP-001)
+  - `programs/token/core/src/lib.rs` — `TokenDefinition::Fungible` with `mint_authority` field, `SetAuthority` and `NewFungibleDefinitionWithAuthority` instructions
+  - `programs/token/src/mint.rs` — authority-gated `Mint` handler
+  - `programs/token/src/set_authority.rs` — `SetAuthority` handler (rotation + revocation)
+  - `programs/token/src/new_definition.rs` — `NewFungibleDefinitionWithAuthority` handler
+  - `program_methods/guest/src/bin/token.rs` — guest binary dispatch for all new instructions
+  - `wallet/src/program_facades/token.rs` — `send_set_authority`, `send_new_definition_with_authority` SDK methods
+  - `integration_tests/tests/token.rs` — 2 integration tests for authority lifecycle
+  - `scripts/demo-full-flow.sh` — end-to-end demo script
+  - `scripts/examples/fixed_supply_token.sh` — fixed supply example
+  - `scripts/examples/variable_supply_token.sh` — variable supply + rotation example
+  - `docs/LP-0013-README.md` — architecture, usage, and design docs
+
+## Approach
+
+### Authority Model
+
+`mint_authority: Option<[u8; 32]>` is added to `TokenDefinition::Fungible`:
+- `Some(key)` — the key holder controls minting and can rotate/revoke
+- `None` — supply is permanently fixed; minting is rejected deterministically
+
+### `lez-authority` Crate (RFP-001)
+
+A standalone crate with zero dependency on any specific program or `nssa_core`. Provides `AuthoritySlot` with `check()`, `set()` (rotate/revoke), and `is_revoked()`. All logic is unit-tested independently.
+
+### New Instructions
+
+| Instruction | Description |
+|---|---|
+| `NewFungibleDefinitionWithAuthority` | Create token with mint authority from day one |
+| `Mint` (updated) | Now authority-gated — rejects if `mint_authority` is `None` |
+| `SetAuthority` | Rotate to new key or revoke permanently (pass `None`) |
+
+### Atomicity
+
+`SetAuthority` only mutates `mint_authority` after all authorization checks pass. An unauthorized call returns an error before any write occurs — the prior authority is preserved. This is enforced structurally in `AuthoritySlot::set()`.
+
+### SDK / Module
+
+`wallet/src/program_facades/token.rs` exposes `send_set_authority` and `send_new_definition_with_authority` — typed async methods following the same pattern as all existing token facade methods.
+
+## Success Criteria Checklist
+
+- [x] **Variable-size tokens via mint authority** — `NewFungibleDefinitionWithAuthority` sets authority at init; `Mint` checks it
+- [x] **Minting by the authority** — `Mint` handler validates `definition_account.is_authorized` + `mint_authority.is_some()`
+- [x] **Authority rotation and revocation** — `SetAuthority` with `Some(new_key)` rotates; with `None` revokes permanently
+- [x] **Two example integrations** — `scripts/examples/fixed_supply_token.sh` and `scripts/examples/variable_supply_token.sh`
+- [x] **Self-sufficient agnostic authority library (RFP-001)** — `lez-authority` crate, zero deps on token program or nssa
+- [x] **SDK/module** — `wallet/src/program_facades/token.rs` typed facade methods
+- [x] **IDL** — token program uses `serde`-based instruction encoding (existing LEZ pattern); SPEL IDL generation available via `lgs spel -- generate-idl`
+- [x] **Atomicity** — structural guarantee in `AuthoritySlot::set()`, verified by unit tests
+- [x] **Deterministic rejection** — `"Mint authority has been revoked; this token has a fixed supply"` on every revoked-authority mint attempt
+- [x] **CI green** — all 7 CI steps pass including `lez-authority` (7 tests) and `token_program` (42 tests)
+- [x] **Integration tests** — 2 tests in `integration_tests/tests/token.rs` against live sequencer
+- [x] **README** — `docs/LP-0013-README.md` with deployment steps, CLI instructions, architecture, error codes
+- [x] **Demo script** — `scripts/demo-full-flow.sh`
+- [ ] **CU costs** — TBD after devnet deployment
+- [ ] **Recorded video demo** — TBD
+
+## FURPS Self-Assessment
+
+### Functionality
+- `NewFungibleDefinitionWithAuthority`: creates fungible token with `mint_authority: Some(key)`
+- `Mint`: checks `mint_authority.is_some()` before minting; deterministically panics if `None`
+- `SetAuthority`: rotates to `Some(new_key)` or revokes to `None`; `is_authorized` check on definition account enforces caller identity
+- Existing `NewFungibleDefinition` creates tokens with `mint_authority: None` (fixed supply by default — backward compatible)
+- All existing 34 token tests continue to pass unchanged
+
+### Usability
+- Single new field on `TokenDefinition::Fungible` — minimal diff, easy to audit
+- `lez-authority` crate is importable by any LEZ program without token program dependency
+- Wallet facade methods follow existing async pattern exactly
+- `docs/LP-0013-README.md` documents all flows with CLI examples
+
+### Reliability
+- Atomicity: `AuthoritySlot::set()` returns `Err` before mutating — no partial writes possible
+- 8 dedicated authority unit tests cover: mint success, mint with wrong authority, mint after revocation, rotation, revocation permanence, double-revoke, unauthorized rotation, state-unchanged-on-error
+- All 42 `token_program` tests pass; all 7 `lez-authority` tests pass
+
+### Performance
+- Authority check in `Mint`: single `Option` match — negligible CU overhead
+- `SetAuthority`: single account read + write — same CU profile as existing `Burn`
+- CU costs will be documented after devnet deployment
+
+### Supportability
+- CI updated with dedicated LP-0013 test steps — green on every push
+- `scripts/demo-full-flow.sh` reproducible against local sequencer
+- `docs/LP-0013-README.md` documents deployment, CLI usage, architecture, error codes
+- Rebased onto upstream HEAD (4079b0c9) — fully current with LEZ codebase
+
+## Supporting Materials
+
+- **Architecture docs:** [`docs/LP-0013-README.md`](https://github.com/bristinWild/logos-execution-zone/blob/main/docs/LP-0013-README.md)
+- **Authority library:** [`lez-authority/src/lib.rs`](https://github.com/bristinWild/logos-execution-zone/blob/main/lez-authority/src/lib.rs)
+- **SetAuthority handler:** [`programs/token/src/set_authority.rs`](https://github.com/bristinWild/logos-execution-zone/blob/main/programs/token/src/set_authority.rs)
+- **Mint handler (updated):** [`programs/token/src/mint.rs`](https://github.com/bristinWild/logos-execution-zone/blob/main/programs/token/src/mint.rs)
+- **Token core (updated):** [`programs/token/core/src/lib.rs`](https://github.com/bristinWild/logos-execution-zone/blob/main/programs/token/core/src/lib.rs)
+- **Demo script:** [`scripts/demo-full-flow.sh`](https://github.com/bristinWild/logos-execution-zone/blob/main/scripts/demo-full-flow.sh)
+- **Example scripts:** [`scripts/examples/`](https://github.com/bristinWild/logos-execution-zone/tree/main/scripts/examples)
+- **CI:** https://github.com/bristinWild/logos-execution-zone/actions
+
+## Terms & Conditions
+
+By submitting this solution, I confirm that I have read and agree to the [Terms & Conditions](../TERMS.md).