Senior Backend / Platform Engineer
Causa Prima · Madrid · onsite
You'll own the platform our agents run on — event-driven architecture, data pipelines, integrations with customer accounting systems, and the infrastructure that makes everything reliable, auditable, and fast.
What you'll do
- Event store — Append-only PostgreSQL with tamper-evident hash chaining, real-time event distribution, agent replay and recovery, schema versioning.
- Cryptographic signature infrastructure — Key management, signature verification on all agent events, approval chains for external actions.
- Workflow Constraint Engine — The gateway that verifies authorization before any external action (email, payment, API call) proceeds.
- PII Vault & GDPR compliance — Isolated, encrypted storage for personal data. Right to erasure. Data residency per region.
- Multi-tenancy — Row-level security, tenant isolation across all data stores, tenant-scoped LLM API keys.
- Authorization (Cerbos) — Attribute-based access control for agents and humans. Deterministic policy evaluation — LLMs never make auth decisions.
- MCP security layer — Authentication, capability-based scoping per partner, and rate limiting for the Model Context Protocol endpoint.
- Database architecture — PostgreSQL schema design, indexing strategy, performance tuning, read replica topology.
What we're looking for
- 3+ years experience with Python and/or TypeScript in production.
- 5+ years designing backend platforms for production systems.
- Strong systems design skills — this is the primary requirement. You think in boundaries, contracts, failure modes, and scaling characteristics.
- Deep PostgreSQL knowledge — RLS, indexing tradeoffs, event sourcing patterns, schema evolution.
- Strong application security architecture skills: encryption models, key management, auth patterns.
- Experience with policy-as-code authorization (Cerbos, OPA, Cedar, or similar).
- Strong code review skills for security-sensitive AI-generated code.
- Nice to have:
- Cryptographic primitives in production (digital signatures, hash chaining, application-layer encryption).
- Event streaming platforms (Kurrent, Redpanda, Kafka).
- SOC 2 or GDPR compliance engineering.
- Fintech or regulated-environment background.