glm-5.2
cb98f42cd4
Add ADR-026 (vault key model — HD derivation) recording the foundational HD-derivation decision, 74' coin type reservation, SLIP-0010/Ed25519 default, secp256k1 feature-gating, and AES-256-GCM cipher choice. These were previously inline rationale with no ADR (W9). Extend ADR-018 with an explicit EncryptedData wire format lock — fields, encoding, and semantics are frozen; no removal without a format-version migration (W10). Resolve the remaining guard clauses and spec decisions: - W2: Capabilities must be immutable after construction (no interior mutability). Makes the Arc vs deep-copy clone semantics genuinely two-way. - W5: Published to_* specs are compatibility contracts — best-effort mappings are two-way before first publication, one-way after. Version generated specs. - W6: Salt field clarification — v2 salt is permanently unused; a future KDF is a different derivation family, not a version-indexed path; the field saves a wire-format change only. - W7: unlock_new returns Zeroizing<String> — the mnemonic is the root of trust and must not linger in freed memory. - W17: OQ-09 WASM — server-side dispatch door is honestly closed (Connection is concrete, tokio-bound), not implicitly preserved. - W18: OQ-10 git — composability fork (raw smart protocol vs call-protocol projection) is a separate decision from ERC721 scope. - W20: from_openapi must prefix imported error codes (HTTP_404) to avoid collision with protocol-level codes (NOT_FOUND). Normative rule, not naming convention. - W21: ScopedOperationEnv field is private — construction via new()/ empty(), query via allows(). Makes the future subgraph refactor non-breaking. - C13: Connection::set_identity — the endpoint does not read identity() after handle() returns (Connection is moved into the spawned task). Observability is handler-side logging. Simplest honest answer. - W1: OperationAdapter trait is async, returns Vec<HandlerRegistration>. from_call requires async discovery; ADR-022 changed the return type. - W11: CompositionAuthority::as_identity() defined — constructs a synthetic Identity (label as id, scopes, resources) not resolvable via IdentityProvider. Second Identity construction path, acknowledged. - W14: SecretKey is iroh::SecretKey (Ed25519) — consistent with the endpoint's iroh dependency. - W19: Grandchild abort propagation is inherit-by-default (option a) — invoke() with no explicit policy inherits parent's policy. ContinueRunning auto-propagates to grandchildren unless explicitly overridden.
210 lines
9.6 KiB
Markdown
210 lines
9.6 KiB
Markdown
# ADR-018: Vault as Standalone Crate
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## Status
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Accepted
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## Context
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alknet-vault provides BIP39 mnemonic generation, SLIP-0010 Ed25519 HD key
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derivation, BIP-0032 secp256k1 derivation (feature-gated), and AES-256-GCM
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encryption. It holds the master seed — the root of trust for all derived keys
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and encrypted credentials in the alknet system.
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The question is: what does alknet-vault depend on? The candidates:
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1. **Depend on alknet-core** for shared types (errors, maybe Identity). This
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pulls QUIC, quinn, iroh, rustls, and tokio runtime dependencies into the
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vault's dependency tree.
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2. **Stand alone** — zero alknet crate dependencies. The vault defines its own
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types, its own error enum. Other crates depend on
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the vault; the vault depends on nothing in alknet.
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This is a one-way door. Once the vault depends on alknet-core, reversing it
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requires removing that dependency from every type, error conversion, and
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test — and the longer it stays, the more entangled it becomes.
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### Why standalone matters
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The vault is used in contexts where QUIC networking does not exist:
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- **CLI tools**: a key-derivation utility that derives an identity key from a
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mnemonic without starting a network endpoint.
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- **Test harnesses**: integration tests in other crates derive test keys
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without spinning up a QUIC endpoint.
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- **WASM key derivation**: a future WASM target that derives keys in a browser
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(the BiStream trait in ADR-007 preserves this door at the transport layer;
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the vault's independence preserves it at the secret layer).
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- **Embedded assembly**: a binary that only needs the vault to decrypt a
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config file at startup, with no networking at all.
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If the vault depends on alknet-core, all of these contexts pull in quinn,
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iroh, rustls, and tokio — none of which they need. The vault's job is
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cryptographic derivation and encryption. It has no networking concern.
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### What the vault provides without alknet-core
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The vault defines its own types and traits:
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- `Mnemonic`, `Seed` — BIP39 root material
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- `ExtendedPrivKey` (Ed25519), `Secp256k1ExtendedPrivKey` (Ethereum) —
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derived key material
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- `DerivedKey`, `KeyType` — protocol-level key representation
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- `EncryptedData`, `EncryptionKey` — AES-256-GCM blobs
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- `VaultServiceHandle` — runtime API (direct method calls; no actor, no
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message enum — see ADR-025)
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- `VaultServiceError` — its own error enum (string-wrapped sub-errors; the
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vault doesn't share an error type with alknet-core)
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The vault uses direct method calls on `VaultServiceHandle`, not irpc
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dispatch (ADR-025). The vault is local-only by construction — no remote
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dispatch capability, no `RemoteService` trait, no wire format for vault
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messages. If remote vault access is ever needed, it's a separate crate that
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wraps the vault (see ADR-025, OQ-021).
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## Decision
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**alknet-vault has zero alknet crate dependencies.** It depends only on
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external crates (`bip39`, `ed25519-bip32`, `aes-gcm`, `sha2`, `hmac`,
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`secp256k1`, `tokio` for `RwLock` sync primitives, `serde`,
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`zeroize`, `thiserror`, `base64`, `rand`). ADR-025 dropped `irpc`,
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`irpc-derive`, and `postcard` — the vault no longer uses irpc dispatch.
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The vault does not depend on:
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- `alknet-core` — no shared types, no `Identity`, no `AuthContext`
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- `alknet-call` — no `OperationSpec`, no `OperationContext`, no call protocol
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- `alknet-vault` does not implement `ProtocolHandler` — it has no ALPN (see
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ADR-019)
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Dependency flow is strictly one-directional:
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```
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alknet-vault (standalone)
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↑
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alknet (CLI binary) — the only crate that depends on alknet-vault
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```
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No handler crate depends on alknet-vault directly. Handlers receive derived
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material through capabilities injected by the assembly layer (ADR-014). The
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CLI binary is the sole integration point (ADR-008, ADR-019).
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### Type independence
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The vault defines its own types and does not share types with alknet-core:
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- `VaultServiceError` is the vault's error enum. It is a plain
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`thiserror::Error` (ADR-025 dropped irpc, so vault errors no longer need
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`Serialize`/`Deserialize` for wire dispatch). It does not implement
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`From` for alknet-core error types — the CLI binary converts at the
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assembly boundary.
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- `DerivedKey` is the vault's key representation. It is not shared with
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alknet-core's `Identity` type. The CLI binary extracts the bytes it needs
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(private key for signing, public key for TLS identity) and constructs the
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alknet-core types at the assembly layer.
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- `EncryptedData` is the vault's encrypted blob format. It is shared with
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`alknet-storage` (a future crate) by type-level agreement, not by a crate
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dependency — both crates must agree on the serialization format (see
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[encryption.md](../crates/vault/encryption.md)). The format is **frozen**
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(see Decision below).
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## `EncryptedData` Wire Format Lock
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The `EncryptedData` struct is a **stable wire format** shared with
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`alknet-storage` (a future crate) and the TypeScript consumer
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(`@alkdev/storage`) by type-level agreement, not by a crate dependency.
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Both crates and the TypeScript consumer must agree on the serialization
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format. The format is now explicitly **frozen**:
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```rust
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pub struct EncryptedData {
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pub key_version: u32, // rotation tracking
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pub salt: String, // base64, 32 bytes — unused in v2 (wire-format compat)
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pub iv: String, // base64, 12 bytes — AES-GCM nonce
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pub data: String, // base64 — ciphertext + auth tag
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}
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```
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The frozen compatibility surface:
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- **Fields**: `key_version`, `salt`, `iv`, `data` — no fields may be
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removed or renamed. New fields may be added only if they are optional
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(default on deserialization) and do not change the meaning of existing
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fields.
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- **Encoding**: all binary fields are base64-encoded as strings for JSON
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serialization. This is the cross-language wire format.
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- **Field semantics**: `key_version` selects the derivation path
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(ADR-021). `salt` is unused in v2 but is part of the frozen format —
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it cannot be removed without a format-version migration (a future KDF
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in v3 would use the salt for *new* data, not retroactively for v2 data
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— see ADR-020, W6). `iv` is the 12-byte GCM nonce. `data` is the
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ciphertext with the GCM auth tag appended.
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**Why this needs an explicit lock**: the "type-level agreement, not a
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crate dependency" approach means there is no compiler enforcement of the
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format across crates. The stability contract existed only in prose. An
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implementer modifying `EncryptedData` (e.g., removing the unused `salt`
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field) would find no ADR saying "this format is frozen." This decision
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makes the freeze explicit and enforceable by review.
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**This resolves review #002 W10.**
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## Consequences
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**Positive:**
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- The vault compiles and runs without QUIC, quinn, iroh, rustls, or a tokio
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runtime (the `VaultServiceHandle` works with just `std::sync::RwLock`; the
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actor uses `tokio::sync::mpsc` but that's a lightweight dependency).
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- CLI tools, test harnesses, and future WASM targets can use the vault for key
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derivation without pulling in networking crates.
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- The vault's API surface is stable — changes to alknet-core types don't
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force a vault recompile, and changes to vault types don't force a
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handler recompile (the CLI is the only consumer).
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- No circular dependency risk. The dependency graph is a strict DAG.
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- The vault can be published and used independently of alknet — it's a
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general-purpose local key vault, not an alknet-specific component.
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**Negative:**
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- The vault cannot share types with alknet-core. If a type wants to be shared
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(e.g., a future `Fingerprint` type), it must live in alknet-core and the
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vault must define its own equivalent, or a new shared crate must be
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created. This is a feature, not a bug — it forces explicit boundaries.
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- The CLI binary must convert between vault types and alknet-core types at
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the assembly boundary. This is a small amount of glue code (extract bytes
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from `DerivedKey`, construct alknet-core types). See ADR-019.
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- The vault's `VaultServiceError` is separate from alknet-core's
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`HandlerError`. The CLI binary maps vault errors to handler errors or
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startup failures. This is expected — the vault is a library, not a
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handler.
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## Assumptions
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1. **The vault's API is consumed by one component (the CLI binary) in the
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alknet system.** If a future use case requires multiple crates to depend
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on the vault directly, the dependency flow still holds — they depend on
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the vault, the vault depends on nothing. The standalone property is
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preserved.
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2. **Shared types between the vault and other crates are agreed by type-level
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compatibility, not by a crate dependency.** `EncryptedData` is the example:
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both the vault and `alknet-storage` (future) must agree on the
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serialization format. This is documented in the type's spec, not enforced
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by the type system across crates.
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3. **The vault's error type does not need to integrate with alknet-core's
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error handling.** The vault returns `VaultServiceError`; the CLI binary
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handles it at the assembly boundary. If a future use case requires
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propagating vault errors through alknet-core's error types, the CLI
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converts at the boundary.
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## References
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- ADR-003: Crate decomposition (alknet-vault is standalone)
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- ADR-005: irpc as call protocol foundation (irpc remains the foundation
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for alknet-*call*; the vault no longer uses irpc — see ADR-025)
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- ADR-025: Vault local-only dispatch (dropped irpc from the vault; the
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vault uses direct method calls, no actor, no remote capability)
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- ADR-008: Vault integration point (CLI-embedded, assembly-layer only)
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- ADR-014: Secret material flow and capability injection
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- ADR-019: Vault assembly-layer-only access
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- [crates/vault/README.md](../crates/vault/README.md)
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- Implementation: `crates/alknet-vault/` |