proof-aware-crypto-tooling-agent/WALLET.md

warden — the verified-custody wallet

warden is the acting end of pacta. Where the rest of the project decides which cryptographic code is trustworthy, warden runs on that decision: it builds an Ed25519 custody boundary out of the four independently proven curve25519-dalek forks, and puts them to work guarding money- adjacent signatures — inbound and outbound.

It is agent-native first. The primary interface is an MCP server; a human CLI is provided for operation and inspection. The design research behind that choice is in docs/agent-native.md.

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The one idea

Inbound acceptance requires a unanimous quorum of provably-equivalent verifiers. Outbound signatures must pass the same quorum before release.

Each quorum member is an Ed25519 verifier compiled from a source workspace whose correctness certificates are machine-checked in Lean 4 and replay- attested in the public Lean Transparency Log. The four members — dalek, anza, risc0, betrusted — are genuinely different codebases, but each is proven to decide the same predicate:

accept(A, m, R, s)  ⇔  decompress(R) = [k](−A) + [s]B

Classic N-version programming hopes independent implementations won't share a bug. warden doesn't hope: on the proven domain the members cannot disagree about semantics, so a runtime disagreement is not a difference of opinion — it is evidence of build corruption, a memory fault, or tampering. That turns "the verifiers disagreed" from a shrug into an alarm with a machine-checked guarantee behind it.

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Trust posture (read this before trusting it)

surface	assurance
inbound verification	custody-grade — quorum of certificate-covered verify paths
outbound firewall (verify-after-sign)	custody-grade — same quorum
outbound signing itself	trusted base — the attested artifact, not a third implementation; not covered by any theorem
SHA-512	opaque oracle inside the theorems
wire parsers	outcomes are hypotheses
reproducible builds, side channels	not claimed (that is R5)
ML-DSA / PQC	fail-closed: no proven implementation exists

The asymmetry is the point: warden is strongest exactly where it matters most for custody — deciding whether an inbound authorization is real — and honest about the weaker outbound edge, which it fences with the firewall.

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Anatomy of a wallet

A wallet is a directory of evidence, not a database of secrets:

capsule.json     the sealed custody capsule: quorum members, their attested
                 source commits, the transparency-log receipts that
                 authorized them (the R4 gate), and the policy in force
ledger.jsonl     append-only, SHA-256 hash-chained event log
keys/            wallet identities (local signer keys are 0600; the airgap
                 identity has no private key on this host)
incidents/       quorum divergences and firewall quarantines, full trails
receipts/        refusal receipts — signed, machine-actionable
quarantine/      signatures the firewall refused to release
airgap/          outbox/inbox for the Precursor-style gap signer
latch.json       present and latched=true when custody is frozen

Every state change — inbound verify, outbound sign, refusal, incident, latch, unlatch — is a hash-chained ledger entry. pacta wallet verify-ledger recomputes the chain; a single altered byte anywhere in the history is caught.

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The R4 gate, in executable form

pacta wallet init refuses to create a wallet unless, for every member:

1. the built binary's provenance names an attested source commit;
2. the evidence dir holds that component's attestation + inclusion receipt;
3. the attestation re-validates locally — verdicts are re-derived from observed axiom cones, never taken from the provider's label;
4. the local score reaches the required tier (default R4);
5. the receipt's inclusion proof verifies against its signed tree head, under the log public key you pass;
6. the source commit the binary was compiled from matches the attested one.

Miss any of these and wallet creation fails with the reasons listed. A custody wallet that cannot show its evidence has no business existing.

--trusted-provider is required: you must name whose observations you are consuming. You are never asked to trust their verdicts.

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Quickstart

# 0. one-time: build the dogfood signer + the four quorum members
pacta dogfood-build --source <…>/curve25519-dalek-source
pacta wallet build-quorum --sources-root <…>/sources     # dalek anza risc0 betrusted

# 1. fetch fresh evidence for each fork from the live log
for c in dalek anza risc0 betrusted; do
  pacta log-fetch --url https://ltl.zkdefi.org \
    --component ${c}-ed25519-verified --out-dir ./evidence
done

# 2. create the wallet (R4 gate)
pacta wallet init --wallet ./my-warden --evidence ./evidence \
  --log-public-key ./log.pub --trusted-provider local-pacta-provider

# 3. inspect
pacta wallet status --wallet ./my-warden
pacta wallet card   --wallet ./my-warden          # the self-proving custody card

# 4. serve the agent-native surface
pacta wallet mcp --wallet ./my-warden             # stdio JSON-RPC MCP server

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Agent-native surface (MCP)

pacta wallet mcp speaks MCP over stdio JSON-RPC. Seven outcome-first tools; strict input schemas; results carry evidence; errors are structured objects, never prose.

tool	does
wallet_status	custody posture: members/tiers, latch, ledger head + chain integrity, counts
verify_inbound	run the quorum on (payload, signature, public_key); unanimity or a classified incident
request_signature	intent-bound outbound signing through the firewall; refusal object on any gate
custody_card	the self-proving card (embedded inclusion proofs; recompute, don't believe)
posture_challenge	nonce → firewalled, signed posture attestation with the quorum trail
list_incidents	divergences and quarantines, newest-first
explain_refusal	fetch a refusal receipt by index (or latest)

Refusal codes (every refusal names one): EVIDENCE_REQUIRED, POLICY_DENIED, CUSTODY_LATCHED, EVIDENCE_STALE, MALFORMED_INTENT, SIGNER_UNAVAILABLE, FIREWALL_QUARANTINE, PENDING_AIRGAP.

The custody card is self-proving

Unlike an A2A agent card that you take on the operator's signature, the warden card embeds, per member, the transparency-log inclusion proof and signed tree head. A counterparty recomputes the Merkle roots and checks the STH signature against the log key it already pins — trust by recomputation, not by assertion. See verify_posture_attestation and the log's own verify.py for the ~40-line client side.

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The signing firewall (verify-after-sign)

Outbound is: intent → sign → firewall → release.

1. intent — a structured envelope whose purpose is recorded (the ledger stores why, not only what) and whose payload_sha256 binds the request to exact bytes.
2. sign — either the local dogfood signer or the airgap/Precursor signer (seed never on this host; request parked in airgap/outbox, response read from airgap/inbox).
3. firewall — the fresh signature faces the full quorum. This is the textbook fault-injection countermeasure: a glitched or tampered signer is caught before anything leaves the building.
4. release — only unanimity releases. A rejected self-signature is quarantined, never returned, and custody latches.

A latched wallet refuses all outbound with CUSTODY_LATCHED, and — by design — its refusals arrive unsigned: a wallet that no longer trusts its own boundary does not certify its apologies. pacta wallet unlatch --note "<why>" is a deliberate operator act; the note is recorded permanently in the ledger next to the latch it releases.

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Divergence taxonomy

The forks' accept() predicates are allowed to differ only on documented degenerate inputs (anza rejects A = 0 and a legacy excluded-small-order- R list). warden fails closed regardless; the taxonomy only grades the alarm:

classification	when	verdict	incident
unanimous-accept	all accept	accept	—
unanimous-reject	all reject	reject	—
semantic-edge	disagree AND a documented edge flag applies	reject	note
unexplained	disagree with no explanation (or a member errored)	reject	tamper → latch

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Product lineup

warden ships as one core with four production-ready deployment profiles — see docs/products.md. In one line each:

• warden-solo — a single agent's custody sidecar (local signer).
• warden-airgap — signing behind a Precursor/Betrusted hardware gap.
• warden-treasury — trust-minimized chain watching (re-verify with the chain's own proven verifier; the RPC is demoted to bandwidth).
• warden-choir — N wardens cross-witnessing each other's ledgers.