Add USDT0 (LayerZero OFT) to the cross-chain and assets skills

README.md

@@ -84,7 +84,7 @@ skills/
 ├── agentic-payments/          # AI/machine payments — SKILL.md router + x402 / mpp files
 ├── zk-proofs/SKILL.md         # ZK verification (BLS12-381/BN254 Groth16, UltraHonk), Circom/Noir/RISC Zero
 ├── standards/                 # SEPs & CAPs — SKILL.md router + ecosystem / resources files
-└── cross-chain/               # Cross-chain — SKILL.md router + cctp file
+└── cross-chain/               # Cross-chain — SKILL.md router + cctp / axelar / layerzero files
 ```
 
 Each sub-skill is a self-contained Agent Skill with its own frontmatter. Larger skills follow [Anthropic's progressive-disclosure guidance](https://platform.claude.com/docs/en/agents-and-tools/agent-skills/best-practices): a sub-500-line `SKILL.md` router with a task-to-file table, plus companion files (one level deep) that load only when the task needs them. Cross-references link related skills (e.g., the `agentic-payments` skill points to `smart-contracts` for the SACs the protocols call, and to `assets` for USDC). The AI reads only the files relevant to the task at hand.
@@ -118,7 +118,7 @@ Contributions are welcome! Please ensure any updates reflect current Stellar eco
 
 ## Evaluations
 
-[`evals/`](evals/README.md) holds ~3 task scenarios for each of seven skills (plus cross-skill routing checks and a negative control), each encoding a mistake agents actually make without the skill. Three grading tiers: machine-checkable compile checks, LLM-judged behavior assertions, and skill-trigger checks. Two gaps are open: `cross-chain` has no scenarios yet, and no baseline transcripts are committed, so the set is still unvalidated. See [evals/README.md](evals/README.md) for the format, how to run them, and what the missing baselines mean.
+[`evals/`](evals/README.md) holds ~3 task scenarios for each of the eight skills (plus cross-skill routing checks and a negative control), each encoding a mistake agents actually make without the skill. Three grading tiers: machine-checkable compile checks, LLM-judged behavior assertions, and skill-trigger checks. One gap is open: no baseline transcripts are committed, so the set is still unvalidated. See [evals/README.md](evals/README.md) for the format, how to run them, and what the missing baselines mean.
 
 ## Resources
 

evals/README.md

@@ -1,6 +1,6 @@
 # Skill Evaluations
 
-Representative task scenarios for seven of the eight skills in this repo, following [Anthropic's evaluation-driven skill authoring guidance](https://platform.claude.com/docs/en/agents-and-tools/agent-skills/best-practices#evaluation-and-iteration). `cross-chain` landed after this set was written and has no scenarios yet. Each scenario encodes a mistake an agent actually makes *without* the skill — several come from real failure modes (the #41 compile bugs, documented pitfalls in agentic-payments, the ZK curve trap), not imagined ones. Run them before publishing skill changes so regressions get caught here instead of by users.
+Representative task scenarios for all eight skills in this repo, following [Anthropic's evaluation-driven skill authoring guidance](https://platform.claude.com/docs/en/agents-and-tools/agent-skills/best-practices#evaluation-and-iteration). `cross-chain` landed after this set was written; its scenarios arrived with the USDT0 rail. Each scenario encodes a mistake an agent actually makes *without* the skill — several come from real failure modes (the #41 compile bugs, documented pitfalls in agentic-payments, the ZK curve trap), not imagined ones. Run them before publishing skill changes so regressions get caught here instead of by users.
 
 ## Scenario format
 

evals/scenarios/assets/04-sac-admin-handover.json

@@ -0,0 +1,13 @@
+{
+  "skills": [
+    "assets"
+  ],
+  "query": "We want our Stellar token minted only by our contract, and the issuer account locked. What is the order of operations?",
+  "expected_behavior": [
+    "Calls `set_admin` on the SAC first, while the issuer can still sign, because the issuer is the SAC's initial admin",
+    "Locks the issuer (master key weight 0) only after that handover",
+    "Warns that locking the issuer first strands the SAC admin at the locked issuer forever, since nobody can authorize the first `set_admin`",
+    "Keeps the two controls apart: the issuer lock stops classic minting, the SAC admin decides who mints through the contract",
+    "Does not claim a locked issuer disables the SAC's `mint` under the new admin"
+  ]
+}

evals/scenarios/cross-chain/01-usdt-arbitrum-to-stellar.json

@@ -0,0 +1,15 @@
+{
+  "skills": [
+    "cross-chain"
+  ],
+  "query": "Our users hold USDT on Arbitrum. Let them move it into their Stellar accounts.",
+  "expected_behavior": [
+    "Routes to USDT0 over LayerZero's OFT rail, not CCTP (which carries USDC only) and not a hand-rolled wrapped-asset bridge",
+    "Requires an account (`G…`) recipient's USDT0 trustline to exist before anything inbound is sent, and does not impose that trustline on a contract (`C…`) recipient, whose SAC balance lives in contract storage",
+    "Requires a `C…` recipient to be deployed before the source chain sends, because `resolve_address` falls back to a `G…` account when no contract with those 32 bytes exists, and that account can never be given a trustline",
+    "Checks the recipient contract's instance TTL as well, because delivery is asynchronous and an archived instance takes the same account fallback",
+    "Pins the asset by code and issuer and derives the SAC with `stellar contract id asset` instead of copying an address from a website",
+    "Names Stellar's LayerZero endpoint ID 30600 and encodes the recipient as the decoded 32-byte strkey payload (Ed25519 public key for `G…`, contract ID hash for `C…`), not the strkey string and not with its version byte or checksum",
+    "Does not treat the issuer's missing home_domain / stellar.toml as evidence the asset is fake"
+  ]
+}

evals/scenarios/cross-chain/02-usdt0-send-loses-digit.json

@@ -0,0 +1,13 @@
+{
+  "skills": [
+    "cross-chain"
+  ],
+  "query": "When I send USDT0 off Stellar the last digit of my amount disappears. What is going wrong?",
+  "expected_behavior": [
+    "Explains the SAC's 7 local decimals against the OFT's shared_decimals of 6, so decimal_conversion_rate is 10 and the remainder below 6 decimals cannot cross",
+    "Says nothing is broken: the OFT removes that remainder before it builds the message",
+    "Makes the remainder's destination conditional on the route's OFT fee — it stays with the sender when effective_fee_bps(dst_eid) is 0, and is absorbed into the fee when the rate is above 0",
+    "Tells the user to trust quote_oft's OFTReceipt (amount_sent_ld and amount_received_ld) over their own input amount",
+    "Does not propose scaling the amount with floating-point arithmetic"
+  ]
+}

evals/scenarios/cross-chain/03-usdt0-testnet-rehearsal.json

@@ -0,0 +1,12 @@
+{
+  "skills": [
+    "cross-chain"
+  ],
+  "query": "Before we ship, rehearse our USDT0 bridge integration end to end on Stellar testnet.",
+  "expected_behavior": [
+    "States that USDT0 publishes no Stellar testnet deployment, so a USDT0 testnet round trip is not available",
+    "Offers the real alternatives: read-only quote_oft and quote_send simulation, then a dust-sized mainnet transfer",
+    "Mentions that LayerZero's own testnet endpoint (EID 40600) can carry your own OApp or OFT, and says to confirm one delivered testnet message before trusting it as a rehearsal path",
+    "Does not invent a USDT0 testnet contract address or claim a testnet deployment exists"
+  ]
+}

evals/scenarios/cross-chain/04-usdt0-stellar-to-ethereum.json

@@ -0,0 +1,15 @@
+{
+  "skills": [
+    "cross-chain"
+  ],
+  "query": "Write up what happens to the tokens when our treasury moves USDT0 from Stellar to Ethereum, and then back.",
+  "expected_behavior": [
+    "Does not describe the route as burn-and-mint on both ends: the OFT mode is per leg",
+    "Says the Stellar leg is a MintBurn OFT, so `send` burns on the SAC and an inbound message mints through the SAC manager",
+    "Says the Ethereum leg is an OFT Adapter over canonical Tether USDT, so it unlocks USDT on arrival and locks USDT on the way back, with an ERC-20 approval to the adapter first",
+    "Tells the reader to confirm the mode per route — `oft_type()` on Stellar, and the `OFT` versus `OFT Adapter` entry on USDT0's deployments page",
+    "Quotes with `quote_oft` and `quote_send` rather than assuming the sent amount equals the received amount",
+    "Discovers the route with `min_amount_ld` set to 0, because both quotes enforce that floor and panic `SlippageExceeded`, then re-runs `quote_oft` and `quote_send` with the treasury's accepted minimum immediately before `send`",
+    "Keeps the two units apart: `min_amount_ld` is USDT0 in 7 decimals, while the messaging fee is XLM in stroops"
+  ]
+}

evals/scenarios/cross-chain/05-oapp-fee-quote.json

@@ -0,0 +1,14 @@
+{
+  "skills": [
+    "cross-chain"
+  ],
+  "query": "In our Stellar OApp, how do we quote and pay the LayerZero messaging fee?",
+  "expected_behavior": [
+    "Quotes with `__quote` and passes the returned `MessagingFee` to `__lz_send`, rather than guessing an amount",
+    "Names both fee fields: `native_fee` in XLM and `zro_fee` in the ZRO token",
+    "Says `__lz_send` pays ZRO whenever `zro_fee` is not 0",
+    "Separates the two no-ZRO failures: `__quote` with `pay_in_zro = true` fails in the endpoint with `EndpointError::ZroUnavailable`, while `__lz_send` fails earlier in `__pay_zro` with `OAppError::ZroTokenUnavailable` and never reaches the endpoint",
+    "Passes `pay_in_zro = false` unless a ZRO token is read on that endpoint",
+    "Re-quotes per send instead of reusing an earlier fee number"
+  ]
+}

site/src/data/skills.ts

@@ -132,9 +132,9 @@ export const SKILL_CARD_SOURCES: readonly SkillCardSource[] = [
   {
     source: "skills/cross-chain/SKILL.md",
     category: "Cross-Chain",
-    title: "Cross-Chain (CCTP, Axelar)",
+    title: "Cross-Chain (CCTP, Axelar, LayerZero)",
     description:
-      "Bridge native USDC with Circle CCTP, pass messages and tokens with Axelar GMP/ITS, and route intent-based swaps with NEAR Intents.",
+      "Bridge native USDC with Circle CCTP and native USDT with USDT0, pass messages and tokens with Axelar GMP/ITS and LayerZero OApp/OFT, and route intent-based swaps with NEAR Intents.",
   },
 ] as const;
 

skills/assets/SKILL.md

@@ -406,6 +406,26 @@ SAC implements the standard SEP-41 token interface:
 > compatibility of a normal asset (DEX, anchors, wallets, trustlines) while
 > still layering on custom logic. Prefer a custom contract token only when
 > you need token behavior the SAC genuinely cannot express.
+>
+> **This runs in production today.** USDT0
+> (`USDT0:GATISXX6BZ6NC7IKQBY37CJD4SOZL3CYZJWXEDG6JVIY4WBS6KXJHN6Q`) is a
+> classic asset whose SAC admin is a contract: a role-gated manager that
+> forwards `mint`, `clawback`, `set_authorized`, and `set_admin` to the SAC,
+> with a cross-chain bridge holding only the minter role. See
+> [setting a custom SAC admin](https://developers.stellar.org/docs/build/guides/tokens/custom-sac-admin)
+> for the pattern and `../cross-chain/layerzero.md` for that deployment.
+>
+> One hard prerequisite: **lock the issuer** (master key weight `0`).
+> Payments from a classic issuer are minting, so an unlocked issuer can mint
+> outside the contract and bypass the role model entirely.
+>
+> **Do it in this order: `set_admin` first, then lock the issuer.** A SAC's
+> admin starts as the issuer account, and only the *current* admin can
+> authorize the first `set_admin`. Lock the issuer before that call and the
+> admin stays the locked issuer forever, because nobody can sign the handover
+> ([SAC admin guide](https://developers.stellar.org/docs/build/guides/tokens/custom-sac-admin)).
+> After the handover the SAC still mints under the new admin, so lock the
+> issuer then.
 
 ### Use SAC When:
 - Need a Stellar asset inside a smart contract
@@ -513,3 +533,14 @@ Standard contract interface for NFTs on Stellar. Reference implementations avail
 - Be cautious of assets with clawback enabled
 - Verify stellar.toml from authoritative source
 - Use well-known asset lists for common tokens
+- **Some live assets have no `stellar.toml` at all.** A missing `home_domain`
+  is not evidence of a scam — USDT0 ships without one. Validate by issuer
+  plus SAC derivation, never by the presence of `home_domain` or a
+  `[[CURRENCIES]]` entry
+- **When `AUTH_REVOCABLE` and `AUTH_CLAWBACK_ENABLED` are both set, check the
+  issuer lock *and* the admin roles before listing the asset.** Those flags
+  mean balances can be frozen or clawed back. A contract SAC admin does not
+  contain that power on its own: an issuer whose master key still signs can
+  mint, freeze and claw back directly, whatever the admin contract allows. So
+  confirm the master key weight is `0`, then identify who holds the admin
+  contract's roles