LiquiLens Trade Safety Gateway

This integration is a read-only sandbox adapter for AI trading copilots. It accepts one exact Trade Safety Request and one operator policy, reads a small set of fixed public evidence endpoints, and issues the deterministic SHA-256-only receipt defined by liquilens_evidence.trade_safety.

It is not an order gateway. It has no broker credentials, broker preview, order-submission route, recommendation route, automatic resize behavior, custody, trade settlement, or real-money authority. An optional x402 route can settle a payment for access to the same assessment; payment cannot alter the policy, evidence, outcome, receipt authority, or order path. Every response carries X-Trade-Safety-Mode: sandbox, X-Trade-Safety-Authority: read-only, and X-Trade-Safety-Execution: disabled. Live-mode assessments deterministically return unavailable because the evidence is context-only, the receipt is not tenant-authenticated, and the broker-preview reference is not_applicable.

HTTP and MCP surface

• GET /healthz reports process health without probing or masking source state.
• GET /v1/capabilities describes static limits, sources, and authority.

Anonymous POST requests share a budget within each gateway worker: 16 requests in flight, 20 new requests per second, a burst of 40, and a 20-second total deadline covering body upload and processing. Rate exhaustion returns HTTP 429; occupied capacity or an expired deadline returns HTTP 503. These responses carry Retry-After: 1, Cache-Control: no-store, and the usual read-only headers. MCP errors retain the JSON-RPC envelope. Retry with backoff and jitter; paid requests, when separately enabled, must also follow the settlement journal's reconciliation rules.

Health and discovery GET requests remain available when the POST budget is full. No IP address or installation identity is stored by this control, and changing forwarding, installation, or monitoring headers cannot bypass it. The limits are per worker, not a fleet-wide quota or a substitute for edge network protection. Operators can lower or raise the bounded budget with TRADE_SAFETY_MAX_IN_FLIGHT (1–64), TRADE_SAFETY_REQUESTS_PER_SECOND (1–100), and TRADE_SAFETY_REQUEST_BURST (1–200); invalid values fail startup. The effective settings are exposed under limits.admission in the capability response.

• POST /v1/check accepts exactly {"request": {...}, "policy": {...}}.
• POST /v1/x402/check is registered only under a complete x402 configuration; it challenges and settles paid access to an otherwise identical assessment.
• POST /mcp supports initialize, ping, tools/list, and tools/call.
• MCP exposes only assess_trade_safety and trade_safety_capabilities.
• MCP negotiates initialization-based 2025-11-25 and stateless 2026-07-28; the latter exposes server/discover metadata and requires matching MCP-Protocol-Version, Mcp-Method, and applicable Mcp-Name headers. Invalid versions or header/body mismatches return HTTP 400.
• After legacy initialization, every subsequent legacy POST must carry MCP-Protocol-Version: 2025-11-25; accepted notifications return HTTP 202 without a JSON-RPC body.
• Browser-originated MCP requests accept only the canonical HTTPS issuer origin; non-browser clients may omit Origin, while any other origin returns HTTP 403. Accepted legacy notifications/initialized posts return HTTP 202 with no body.
• FastAPI publishes generated OpenAPI at /openapi.json and Swagger UI at /docs.

There is deliberately no execution-shaped MCP tool.

Server-owned policy admission

The protocol accepts operator-authored policies, but the public gateway does not let an anonymous caller redefine its safety floor. Before any source request or x402 verification, it admits the supplied policy against a server-owned envelope:

• Seiche and Undertow remain mandatory and STRESS remains a held regime;
• source-age ceilings cannot exceed 8 days for Seiche or 1 day for Undertow and LiquiLens;
• notional, exit-cost, and venue-spread limits must be present and cannot exceed USD 100,000, 50 bps, and 20 bps respectively;
• missing evidence remains fail-closed, live still requires an executable quote and broker preview, and automatic resize remains forbidden; and
• an operator may tighten any limit or admit only exact canonical policy hashes.

Recognized TRADE_SAFETY_POLICY_* settings are documented by trade_safety_gateway.policy_guard. Unknown, malformed, or looser settings fail startup. GET /v1/capabilities publishes the active non-secret envelope.

x402 access and agent discovery

x402 is disabled when every TRADE_SAFETY_X402_* setting is absent. A complete configuration adds the paid route and publishes an exact x402 v2 offer with HTTP Bazaar discovery metadata. The offer binds the canonical request body, resource, price, asset, payee, ResourceInfo, and required extensions with a dedicated quote key. The runtime verifies before assessment, settles only after the protected response exists, and releases only the exact journaled bytes.

Payment identity and transaction provenance stay in the private settlement journal, never in the Trade Safety receipt or adoption telemetry. A settled payment does not turn context-only evidence into an executable quote and does not make a safety result fresh forever. See TRADE-SAFETY-X402.md for configuration, the local liquilens-trade-safety-x402-reconcile operator command, state recovery, and activation gates. The command never calls the facilitator; operators must independently establish settled or definitely-unsettled state before changing an uncertain journal entry.

Fixed evidence adapters

Undertow JSON-RPC text content is ignored. The gateway consumes structuredContent only; Seiche is consumed from its fixed REST representation. Both native objects use exact-key validation, have their unkeyed canonical digests recomputed, and are checked for cross-field consistency after the digest check. The exact uncompressed HTTP entity is hashed independently. Source, observation/as-of, knowledge, producer retrieval, gateway retrieval, native expiry, and local receipt-expiry clocks remain separate.

Undertow completeness is roster-scoped, not a claim about the whole market. The gateway requires exact set equality with its declared six-CEX roster and cross-checks quote conversion, required depth band, per-venue basis-point and dollar costs, best/worst venue, spread, peg, proof, rights, and expiry before using a result. Off-roster CEXs, DEXs, and agent-native venues remain unmeasured by construction; adding or changing a venue requires a reviewed contract update rather than silent acceptance.

Fail-closed and network boundary

• The request and policy—including their cross-reference, current lifetime, and the optional institution slug—are validated before any outbound call.
• The caller policy is admitted against the immutable server safety floor before any outbound call or payment challenge/verification.
• Destinations, methods, MCP tool names, and URL bases are constants. Request bodies cannot provide a URL.
• Redirects, environment proxies, cookies, compression, non-JSON bodies, non-200 responses, malformed/duplicate-key JSON, MCP errors, and missing structuredContent are rejected.
• Request bodies are capped at 64 KiB; source bodies at 1 MiB; gateway responses at 512 KiB. Each upstream operation has a five-second total timeout and a two-second connect timeout.
• Independent eligible sources are fetched concurrently. A source error, producer-declared unavailable state, stale native clock, digest failure, request-hash mismatch, proof failure, or rights mismatch becomes that product's typed unavailable evidence section. Because Seiche and Undertow are mandatory products, the receipt then fails closed.
• The service does not log request bodies, response bodies, secrets, account data, or source exceptions. The bundled command disables access logs.
• Every evidence section and the broker-preview reference carries trade_safety_request_hash(request). Undertow also receives and echoes it; Seiche's native projection digest and request hash receive a separate local binding digest inside the hash-sealed receipt. No nearest-rung result is promoted to exact-order evidence.
• Observe and paper are the only modes sent to Undertow. Live and buy requests never reach its sell-side paper-context tool; they produce typed unavailable evidence instead.
• Requests carrying both notional and a non-null quantity do not reach Undertow until a broker-normalized economic-order digest and reference-price contract can prove both fields describe the same exposure.

Public-source access does not imply real-money or redistribution rights. All three adapters therefore declare metadata_only, context_only, real_money_eligible: false, and executable_quote: false where applicable.

Local development

From this directory, install the repository protocol package and the gateway in one environment:

python3 -m venv .venv
. .venv/bin/activate
python -m pip install -e ../.. -e '.[test]'
pytest
liquilens-trade-safety-gateway

The server listens on 0.0.0.0:8080. Free sandbox mode accepts no API key or broker secret. Enabling x402 requires its dedicated quote-binding secret but still accepts no wallet private key or broker credential. Adoption telemetry is also off by default; an operator can explicitly select a private append-only JSONL path as described in TRADE-SAFETY-TRACTION.md.

Container build

Build from the evidence-carrier repository root so the image contains the exact root Trade Safety implementation:

docker build -f integrations/trade-safety-gateway/Dockerfile \
  --build-arg SOURCE_REVISION="$(git rev-parse HEAD)" \
  --build-arg CREATED="$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
  --build-arg ISSUER_ENDPOINT=https://your-sandbox.example/v1/check \
  -t liquilens-trade-safety-gateway:0.2.2 .
docker run --read-only --tmpfs /tmp:rw,noexec,nosuid,size=16m \
  --cap-drop ALL --security-opt no-new-privileges \
  -p 8080:8080 liquilens-trade-safety-gateway:0.2.2

The Dockerfile pins its base image by multi-platform digest, installs from the committed gateway lock, uses a non-root numeric user, and exposes source/build identity through health and capabilities. Production deployment should also apply egress policy allowing only api.seiche.info:443 and api.liquilens.in:443; application allowlisting is not a substitute for a network policy. Enabling x402 additionally requires egress to the one configured facilitator and a private persistent volume for its journal. With x402 variables absent, a read-only container runs only the free routes; with those variables present but no writable private journal volume, startup fails. A public edge must additionally apply a bounded request quota; the application does not trust client-supplied IP headers as a rate-limit key.

The release workflow publishes an attested multi-architecture OCI package to GHCR. That registry artifact is distribution, not a hosted deployment or an order-authorizing service; it retains the same read-only, hash-only sandbox boundary and must be operated by the adopter. The independent gateway-tag lane publishes OCI only; it builds a wheel as validation evidence but does not publish that wheel, an sdist, or a GitHub Release.

Gateway 0.2.2 has an independent release identity so publishing it does not move or reuse the immutable core v0.19.0 tag. After the release commit has landed on origin/main, an allowlisted release owner may create and push the annotated, signed tag trade-safety-gateway-v0.2.2. The workflow rejects a lightweight or unsigned tag, an unsigned target commit, a target outside origin/main, a gateway/tag version mismatch, or any core VERSION other than 0.19.0. It also rejects pre-existing gateway version, source-commit, or signed tag-object OCI tags before publishing. The gateway-only lane emits no floating latest or core-* alias; its multi-architecture image retains maximum build provenance, an SBOM, a separate GitHub provenance attestation, and the signed Git tag object in its OCI metadata. Conversely, a core v* release may update only core-*, core-sha-*, and latest; it cannot move the gateway-owned semantic version, source-commit, or signed-tag-object aliases.

Focused tests

The tests inject byte-exact fake upstream responses and cover:

• unsupported and invalid sizes never calling Undertow;
• source errors, producer-unavailable results, stale clocks, and digest mismatches failing closed;
• incomplete/off-roster Undertow venue maps and inconsistent conversion, depth, cost, rights, PIT, deployed-SHA, or authority fields failing closed;
• exact response hashing, native-digest retention, and exact-order request-hash binding across both products;
• paper receipts passing and limiting under operator policy;
• live receipts never passing and carrying a not-applicable broker preview;
• conditional, minimal LiquiLens projection;
• server-owned policy admission before network and payment work;
• x402 challenge, exact offer/body binding, verification, settlement, durable replay/reconciliation, terminal failure transport, cookie-free HTTP, age-bounded tombstone retention, stale-response refusal, transfer-method truthfulness, configuration rotation, and local operator CLI input/output safety;
• opt-in closed-schema telemetry without request or payment identity; and
• MCP tool inventory/calls, OpenAPI, sandbox headers, strict JSON, and size limits.

This directory is an implementation artifact only. Building or testing it does not deploy or register a public service.

Optional installation measurement

All public checks and MCP tools work without an account or tracking header. An integration may opt into repeat-installation measurement by generating one random UUIDv4, keeping it across runs, and sending it as X-Liquilens-Client-Id. Never send an account, email, wallet or institution ID. The gateway records only a keyed hash; an installation is not a verified person.

import os
import uuid
from pathlib import Path

identity_path = Path(".liquilens-installation-id")
try:
    descriptor = os.open(identity_path, os.O_WRONLY | os.O_CREAT | os.O_EXCL, 0o600)
except FileExistsError:
    pass
else:
    with os.fdopen(descriptor, "w") as handle:
        handle.write(str(uuid.uuid4()))
headers = {"X-Liquilens-Client-Id": identity_path.read_text().strip()}
# Add these optional headers to your existing REST or MCP HTTP client.

Operator smoke tests must additionally send X-Liquilens-Traffic-Class: synthetic. See the measurement contract for private stdout configuration, cohort limits and the scorecard command.