M2 epic: TWAP + EthFlow modules + module.toml manifests#17
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Adds the dependencies the 0.2 host backends need: - cowprotocol (1.0.0-alpha) for the cow-api submission path (OrderBookApi, OrderCreation, OrderUid, Chain). - alloy-provider / -rpc-client / -transport-ws / -primitives (1.5) for the chain JSON-RPC dispatch. The reqwest feature on alloy-provider engages connect_http; the pubsub/ws features back eth_subscribe-class methods. - redb (2) for local-store. Same crate cowprotocol's own watch-tower picked, so the dep tree does not bifurcate when both are used in the same workspace. - reqwest (0.12, rustls-tls) — direct, so the import survives any future cowprotocol feature rearrangement. - tracing + tracing-subscriber (env-filter + fmt) — replaces the 0.1 eprintln! debug log so the engine can drop into a structured log pipeline without re-instrumenting every host call. - thiserror (2) — typed error enums in each backend. - tempfile + wiremock as dev-deps for the host backend tests. Adds engine.example.toml documenting the [engine] state_dir + per- chain RPC URLs the chain backend reads at boot; data/ is now ignored so a local run does not leave the redb file in tree.
Replaces the 0.2 Unsupported stubs with working backends. Each
capability lives in its own host submodule so the trait impls in
main.rs stay thin (dispatch + project the backend's typed error
onto HostError).
cow_api::submit_order
- Parses the guest's bytes as JSON cowprotocol::OrderCreation.
- Dispatches via cowprotocol::OrderBookApi::post_order.
- Returns the assigned OrderUid as a 0x-prefixed hex string.
cow_api::request
- REST passthrough. The base URL is whichever URL the pool's
OrderBookApi client carries — so OrderBookApi::new_with_base_url
overrides (staging, wiremock) flow through transparently.
- Method/path validated host-side; orderbook 4xx/5xx bodies are
surfaced verbatim so the guest can decode {errorType,description}.
chain::request
- Raw JSON-RPC dispatch over an alloy DynProvider opened from
engine.toml at boot. WebSocket URLs engage pubsub (eth_subscribe);
HTTP URLs use the HTTP transport. Params are passed as
serde_json::RawValue so alloy does not re-encode.
- request-batch falls back to per-call dispatch (same shape as the
earlier stub but now backed by real RPC).
local_store
- redb file under engine_config.engine.state_dir.
- Single shared table. Per-module namespacing is enforced
host-side via [len:u8][module_name][raw_key] prefix on every
key. list_keys strips the prefix before returning to the guest.
logging
- Routes through tracing::event! tagged with module=<namespace>.
- Engine boot installs an EnvFilter-based subscriber; RUST_LOG
overrides the engine.toml log_level.
identity / remote-store / messaging / http stay at Unsupported per
the 0.2 roadmap (keystore / Swarm / Waku land in 0.3).
Tests (14, all green):
- cow_orderbook: pool default chains, unknown-chain typing, REST
GET passthrough, relative-path resolution, unknown-method
rejection, submit_order round-trip — last three under wiremock
so the full HTTP path is exercised without hitting api.cow.fi.
- provider_pool: empty pool surfaces UnknownChain.
- local_store: roundtrip, namespace isolation, delete, list_keys
prefix-stripping, empty-namespace rejection.
End-to-end against modules/example: example.wasm loads under the
new wiring, logs init + on_event through the tracing pipeline.
… death (BLEU-813-817)
…er-pool, supervisor (BLEU-821)
…interfaces (BLEU-819)
…ed_crate_dependencies, drop redundant map_err)
PR #9 specific: - main: warn + return when block/log streams end (WebSocket dropped) - supervisor: simplify dispatch_block by extracting chain_id before move - supervisor: temp_local_store returns (TempDir, LocalStore) instead of leaking - README: correct engine.toml chain syntax to [chains.<id>] with rpc_url Rebased from PR #8: - local_store_redb: table.range() instead of iter() for O(matching) keys - provider_pool: dedupe method clone on the success path - main: hex_encode writes into the pre-allocated buffer - cow_orderbook: drop blank line nit - manifest: collapse nested if and use ? operator (clippy) - alloy_rpc_client / alloy_transport(_ws) imports as _ to satisfy unused_crate_dependencies.
Move the manifest.rs monolith into a directory module with four focused submodules (types, load, capabilities, error). Includes the Subscription enum and the four PR #9 tests for subscription parsing. Behaviour unchanged - pure code motion.
main.rs went from 739 lines of mixed bootstrap + 8 Host trait impls +
CLI parser + event loop to ~125 lines of pure orchestration. New
layout:
- bindings.rs: wasmtime::component::bindgen!() moved out so other
modules can name the generated types.
- cli.rs: Cli struct + manual parser.
- host/state.rs: HostState + WasiView impl.
- host/error.rs: unimplemented / internal_error / hex_encode helpers.
- host/impls/{chain,cow_api,identity,local_store,remote_store,messaging,
logging,clock,random,http,types}.rs: one Host trait impl per file.
- runtime/limits.rs: DEFAULT_FUEL_PER_EVENT + DEFAULT_MEMORY_LIMIT.
- runtime/event_loop.rs: open_block_streams, open_log_streams, run,
wait_for_shutdown_signal, TaggedBlockStream, TaggedLogStream.
Adding a new capability is now a single new file under host/impls/
rather than a 60-80 line diff in main.rs.
local_store_redb.rs was 89% tests, cow_orderbook.rs was 60%, and supervisor.rs was 32% (205 lines absolute). Promote each to a directory module with the test suite living in a sibling tests.rs so impl-side diffs stop competing with test churn for attention.
Carries PR #8 (host backends) + PR #9 (supervisor) + cowprotocol patch. Open upstream: nullislabs#15.
Open upstream: nullislabs#12. Resolved .gitignore by taking the PR #12 additions (.agents/, .claude/, skills-lock.json) plus PR #15's data/. # Conflicts: # .gitignore
Per ADR-0001 (module.toml schema), authored for the two M2
modules:
twap-monitor / module.toml
- capabilities.required = ["logging", "local-store", "chain",
"cow-api"] — matches the Rust imports the BLEU-826/827/828
paths exercise.
- [[subscription]] log on Sepolia (chain_id 11155111) against
ComposableCoW (0xfdaFc9d1902f4e0b84f65F49f244b32b31013b74)
with topic-0 keccak256(
"ConditionalOrderCreated(address,(address,bytes32,bytes))"
) = 0x2cceac5555b0ca45a3744ced542f54b56ad2eb45e521962372eef212a2cbf361.
- [[subscription]] block on Sepolia for the BLEU-827 poll loop.
ethflow-watcher / module.toml
- Same capability set (chain reserved for a future eth_call —
e.g. read the EthFlow refund pointer — without churning the
manifest).
- [[subscription]] log on Sepolia against CoWSwapEthFlow
production (0xbA3cB449bD2B4ADddBc894D8697F5170800EAdeC) with
topic-0 keccak256(
"OrderPlacement(address,(address,address,address,uint256,uint256,
uint32,bytes32,uint256,bytes32,bool,bytes32,bytes32),
(uint8,bytes),bytes)"
) = 0xcf5f9de2984132265203b5c335b25727702ca77262ff622e136baa7362bf1da9.
Both [capabilities.http].allow stay empty: all outbound HTTP
flows through the cow-api capability, which routes via the
host's pinned orderbook URL.
The content hash field is the 0.2 placeholder all-zero sha256;
0.3 will validate it against the loaded component bytes.
Linear: BLEU-834. Ref ADR-0001.
Linear issues delivered by this PRThis M2 epic delivers the following CoW project tickets (renamed from BLEU- prefix; same underlying tickets):
All 9 tickets above have already been transitioned to Done in Linear (the original feature PRs landed via dev/m2-base advance + bleu epic #69; this upstream PR delivers the same work to nullislabs/shepherd:main). |
Three threads from the internal review mirror of upstream nullislabs/shepherd PR #17: 1. ethflow-watcher/module.toml capabilities: move `chain` from required to optional. The comment on the original manifest already said the module does not call `chain` today; declaring it as required widened the grant for a capability the module does not exercise. Optional keeps "future-proofing" (BLEU-855 can use it without manifest churn) without violating least-privilege. 2. ethflow-watcher/module.toml subscription comment: soften the "identical on every chain" claim. cow-rs::ETH_FLOW_PRODUCTION is identical across chains today, but unlike ComposableCoW's CREATE2 address EthFlow has had multiple per-network and per-version deployments historically. Multi-chain config in M5 must re-check per `chain_id` instead of assuming the address carries. Address itself stays unchanged: 0xbA3cB449bD2B4ADddBc894D8697F5170800EAdeC is verified against the live Sepolia deployment (event firing observed in the COW-1064 dry-run on 2026-06-18 + cow-rs canonical constant + multiple load-test runs). 3. README.md module manifest example: the documented `address` field said `0xC92E8bdf79f0507f65a392b0ab4667716BFE0110` labeled "ComposableCoW", but that is the GPv2VaultRelayer (per scripts/lib.sh). ComposableCoW is `0xfdaFc9d1902f4e0b84f65F49f244b32b31013b74`. Fixed the address; expanded the comment to clarify it is the canonical CREATE2 address (same on every supported chain). Stays on `feat/m2-module-manifests-bleu-834` as a stacked branch so upstream PR #17 + internal mirror PR #54 can see the fixes as a separate, atomic commit.
…ance) Filtered subset of the compliance applied in PRs #66/#67 of bleu/nullis-shepherd, restricted to files that exist on the M2 epic head. M3+ files (shepherd-sdk, examples, backtest, deploy artifacts) and M4-coupled hunks (ProviderError typed-source variants, JoinSet reconnect tasks, supervisor restart helper) are skipped — they land via their own upstream PRs. Brings M2 epic in line with the repo-wide rust rubric (typed errors, no anyhow in libs, em-dash sweep, #[non_exhaustive] on public error enums).
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Heads-up — small cleanup pass on this PR's branch and description with no code-tree changes:
M4 and M5 epic PRs are now open as #20 (M4) and #21 (M5) so you have the full grant surface visible. They are independent against |
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Restructured: new PR opens with head= |
M2 epic — consolidated for review
This PR aggregates the M2 deliverable for review. M2 ships two production-shaped modules that consume the M1 host surface end-to-end:
modules/twap-monitor/— indexesComposableCoW.ConditionalOrderCreated, polls watches viaeth_call, buildsOrderCreationand submits via cow-api, appliesOrderPostError::retry_hint()for typed retry classification.modules/ethflow-watcher/— decodesCoWSwapEthFlow.OrderPlacementlogs, lifts the embeddedGPv2OrderDatainto anOrderCreationwithSignature::Eip1271, submits, persistssubmitted:{uid}/dropped:{uid}/backoff:{uid}for re-delivery idempotency.Plus
module.tomlmanifests for both, exercising the capability declaration + subscription contracts.Note on diff scope
nullislabs:mainis the pre-M1 baseline. Until your in-flight M1 PRs (#8 cow-api, #9 supervisor event loop, #12 ADR bundle, #15 cowprotocol patch) merge, the diff here also includes their contents. Once those land, this PR rebases clean to M2-only.To focus the M2 review, the M2-specific paths are:
modules/twap-monitor/modules/ethflow-watcher/chore(deps): bump cowprotocol patch to bleu/cow-rs main (BLEU-822 + BLEU-823 in))Paths that belong to your M1 PRs and can be ignored for M2 review:
crates/nexum-engine/src/host/impls/(M1, runtime: implement cow-api, chain, local-store host backends #8)crates/nexum-engine/src/supervisor.rs+runtime/(M1, runtime: multi-module supervisor + block/log event loop #9)docs/adr/000{1,2,3,4,5,6,7,8}*.md(M1, docs: ADR bundle (0001-0008) — engine and CoW architectural decisions #12)Cargo.tomlworkspace patch entry (M1, chore(deps): patch cowprotocol to bleu/cow-rs main (post-alpha.3) #15)Validation
docs/operations/m2-testnet-runbook.md. Both modules boot against Sepolia public WS, subscriptions stay alive, and EthFlow round-trip was confirmed end-to-end via a real swap.cow.fi swap (decoder fired, build_eth_flow_creation rejected on the orderbook's app_data digest mismatch — the documented limitation).cargo clippy --all-targets --workspace -- -D warningsclean.cargo fmt --all --checkclean.cow-rs dependency
Patches
cowprotocoltobleu/cow-rsmain (rev57f5f55). The fork carries:OrderPostErrorKind+retry_hint()onApiError(cow-rs PR chore: apply rustfmt and silence wit-bindgen clippy lint #4, merged)OrderBookApi::with_base_url(chain, base_url)(cow-rs PR chore(deps): bump wasmtime and wasmtime-wasi from 41 to 45 #5, merged)Drop the patch once
cowprotocol >= 1.0.0-alpha.4ships upstream. Tracked as ADR-0007 + ADR-0004.Architectural notes
strategy.rsis pure logic against&impl Host;lib.rsis the wit-bindgen adapter). ADR-0009 (added in the M3 epic) captures the decision; the M3 SDK enables it.OrderPostErrorKind→RetryAction) lives in the SDK (see M3 epic). M2 modules callclassify_api_error(host_error.data.as_deref()).Architectural surface for review
The host-module architecture surface lives in the M3 epic (the
shepherd-sdkHost trait + ADR-0009); M2 itself consumes the M1 surface as-is and does not touch host architecture. The M3 epic PR carries the architecture write-up.Closes BLEU-813, BLEU-818, BLEU-819, BLEU-820, BLEU-821, BLEU-822, BLEU-823, BLEU-834.
Linear milestone: M2 - TWAP + EthFlow modules.