Two coupled fixes for the same root cause: the coin selector was too
conservative for "send most of what I have" cases.
1. min_change_required now drops to 0 for ada-only sends (kept at
min_utxo_lovelace for asset-bearing sends where change has to
carry leftover policy IDs). Downstream pass2 already folds
sub-min change into fee on the ada-only happy path; the selector
was reserving slack the chain doesn't actually need.
2. fee_pass1 dropped from 500_000 to 200_000. Real fees:
1-in 1-out ada-only send : ~166 k
1-in 2-out (with change) : ~178 k
CIP-25 mint w/ metadata : ~210 k
500_000 was overgenerous safety budget. 200_000 is enough headroom
for the basic-send case (which is the one that needed to drain to
fee) without crowding mint paths (which typically have plenty of
lovelace headroom anyway).
Surfaced 2026-05-05 zeroing out the mainnet test wallet:
2 ADA balance, 1.8 ADA send refused upstream as
"need 3300000 (target+fee+min_change), have 2000000"
even though the chain math was fine. New regression
ada_only_send_can_drain_to_fee covers the case.
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|---|---|---|
| crates | ||
| docs | ||
| .dockerignore | ||
| .gitignore | ||
| Cargo.lock | ||
| Cargo.toml | ||
| Dockerfile | ||
| LICENSE | ||
| README.md | ||
| ROADMAP.md | ||
aldabra
Rust-native Cardano lite wallet with an MCP-server interface — built for LLM-first usage (send, receive, mint, Plutus interaction).
Status: Phase 1 scaffold (2026-05-04). Compiles, structure in place, real wallet primitives still landing. See
ROADMAP.md.
Why
The existing Cardano MCP servers are either read-only doc gateways (Jimmyh-world/Cardano_MCP) or built on Blockfrost (web3-mcp) which is a centralized API we deliberately don't depend on. Sulkta runs its own Koios + Ogmios endpoints on Rackham; we want a wallet that talks directly to those.
Also: it's the first Sulkta Rust project — useful as a workout for
crafting-table's Rust toolchain (per Sulkta-Coop/lucy-infra
spec-crafting-table.md).
Architecture
Three crates in a Cargo workspace:
| Crate | Responsibility |
|---|---|
aldabra-core |
Pure crypto + types. Mnemonic → root key (CIP-3), root → payment + stake key (CIP-1852), address construction, signing. No I/O, no network. This is the security boundary. |
aldabra-chain |
Pluggable backends for chain queries. ChainBackend trait, with Koios as the phase-1 implementation. Ogmios + submission paths in phase 2. |
aldabra-mcp |
Binary. MCP server speaking stdio. Glues core + chain together, exposes tools to the LLM client. |
┌─────────────────────────────┐
LLM client │ aldabra-mcp (bin) │ stdio
─────────► │ tool handlers, lifecycle │ ────►
└──────────┬──────────────────┘
│
┌────────┴────────┐
▼ ▼
┌──────────────┐ ┌──────────────┐
│ aldabra-core │ │ aldabra-chain │
│ keys, sign │ │ Koios/Ogmios │
└──────────────┘ └──────────────┘
MCP tools (target)
Phase 1:
wallet.address— derived base address at account 0, index 0wallet.balance— ADA + native asset balance at the wallet's addresswallet.utxos— list UTXOs
Phase 2:
wallet.send— build, sign, submit a payment (ADA or native)wallet.tx_status— poll a submitted tx hash
Phase 3:
wallet.mint— mint a CIP-25 / CIP-68 native assetwallet.policy.create— generate a policy script (timelock, multisig)
Phase 4:
wallet.script.attach— attach an inline datum + reference scriptwallet.script.spend— spend a Plutus-locked UTXO with redeemerwallet.stake.delegate— delegate to a pool
Build
# Local (requires rustc 1.75+)
cargo build --release
# Through crafting-table (preferred — validates the toolchain there)
crafting-table build aldabra
Run
# Direct invocation (smoke test only — does nothing useful in phase 1)
./target/release/aldabra
# As an MCP server registered with Claude Code:
# add to ~/.claude.json:
# "aldabra": {
# "command": "/path/to/aldabra",
# "env": {
# "ALDABRA_DATA": "/mnt/cache/appdata/aldabra"
# }
# }
Security model
- Mnemonic source: interactive bootstrap on first run, paste once, encrypted at rest with age. Never written to disk in plaintext.
- Derived keys: in-memory only,
ZeroizeOnDropon every container. - Network exposure: stdio MCP transport — never opens a TCP socket. Only the spawning client process can reach it.
- Multi-network: mainnet by default, but
--network preview/--network preprodfor testing without real ADA.
See also
ROADMAP.md— phased buildoutdocs/architecture.md— deeper design notes- txpipe/pallas — the Rust Cardano building blocks we depend on
- Emurgo/cardano-serialization-lib — reference TX builder if pallas-txbuilder doesn't cover something
- modelcontextprotocol/rust-sdk — rmcp, the Rust MCP server SDK we use