Use cases · Ecko

Regulated work

Where you must prove what happened

Insurance claims intake

Typed extraction into structs beats prompt-and-parse, and JSONL tracing gives you a per-claim audit trail with token and cost attribution.

Typed extraction · JSONL tracing · Per-claim attribution

KYC and AML review

secret and reveal keep PII out of logs by construction, and capability grants let you prove a component never had network access.

Secrets by type · Capability grants · Offline mock mode

Clinical note structuring

A package granted empty capabilities is mechanically incapable of exfiltrating PHI - a stronger claim than a policy document.

Pure extraction modules · Typed clinical structs · Trace without content

Legal clause extraction

@ensures contracts in natural language catch semantic errors that types alone cannot - like summaries that invent obligations.

Natural-language contracts · Typed skeleton, semantic guard · Deterministic replay

Money

Where being approximately right is being wrong

Invoice matching and reconciliation

Ecko has a real decimal type with 19.99m literals. Financial matching in a float language is a latent bug.

Decimal literals · Typed line items · The money package

Expense and receipt processing

Typed extraction plus checked overflow plus contracts asserting totals reconcile.

Contracts on totals · Overflow as error · CSV and SQL in the box

Procurement and tender analysis

Public-sector work needs offline reproducibility and no vendor lock-in. One binary, no runtime, deterministic replay.

Single static binary · Mock mode in CI · Vendored packages

Billing and usage anomaly detection

cost and tokens are builtins, so the analyser can account for its own spend.

Built-in metering · Hard budgets · JSONL audit

Classification pipelines

High-volume routing and tagging

Customer support triage

Mock mode is deterministic and schema-valid, so routing logic has real CI tests with no API key and no flakiness.

Deterministic mock mode · Typed labels · One binary on the worker

Trust and safety moderation

pmap for fan-out, hard budgets via ECKO_AI_MAX_CALLS so a runaway queue cannot produce a runaway invoice.

pmap · ECKO_AI_MAX_CALLS · Tracing for appeals

Content tagging and catalogue normalisation

Marketplaces normalising millions of messy supplier feeds into one schema.

Pipeline stages · Batch economics · CSV and SQL IO

Lead qualification and CRM enrichment

Batch personalisation where cost per record is the whole business case.

Per-record metering · Typed CRM structs · Offline replays

Operations

Internal tooling and security workflows

MCP servers for internal systems

The mcp package does client and server, and the capability model is exactly what you want when exposing internal tools to an agent.

mcp package both ways · Grants on imports · One binary deployment

Alert triage and incident summarisation

A single binary drops onto a host with no Python environment to maintain and no dependency drift.

Static binary · Mock mode for runbooks · HTTP and JSON stdlib

Phishing and security alert enrichment

Capability-gated, auditable analysis where the tool cannot quietly grow network access through a transitive dependency.

Declared capabilities · Secrets for IOCs · Trace for IR

CI/CD bots and automated code review

One binary in a container, fast startup, no pip install step that breaks on a Tuesday.

Copy binary, run · Pattern matching · py() escape hatch

Data and engineering

Pipelines, retrieval, and migration at scale

ETL with an AI enrichment stage

Pipelines with |>, plus SQL and CSV in the box. The AI step is a stage, not a separate service.

Pipeline operator · SQL and CSV stdlib · Tracing across stages

RAG over private corpora

embed and the rag/db surface, with capability isolation between the retrieval layer and everything else.

embed builtin · rag and db packages · Split grants

Large-scale codemods and migrations

Deterministic output, real pattern matching, and py() when you need an existing Python library.

Pattern matching · AI for the long tail · py() bridge

Synthetic data and evaluation harnesses

Seeded, deterministic mock mode is a requirement for an eval harness that means anything.

Deterministic mock · Contracts as metrics · ecko test

SaaS products

Multi-tenant features, metering, and customer-facing AI

Multi-tenant AI features

Per-tenant keys, per-request cost(), and JSONL traces that carry a tenant id - so inference spend is attributable without a separate metering microservice.

Built-in metering · Trace per request · Provider config per env

Usage-based billing and plan limits

Hard ceilings via ECKO_AI_MAX_CALLS and exact decimal math when usage converts to an invoice line.

Process-wide call budget · Decimal overage rates · Typed usage records

Customer document upload APIs

Capability-gated handlers, secret fields for filenames, and typed extraction - an upload endpoint that cannot grow arbitrary egress.

Grant at the import · Secrets for paths and content · HTTP in the stdlib

Self-serve onboarding flows

Mock mode in CI for the whole signup funnel, typed extraction from free-text company descriptions, and contracts that block hallucinated plan features.

Deterministic funnel tests · Contracts on suggestions · Single deploy artefact

Web apps

Servers, webhooks, and APIs without a second runtime

Server-rendered SaaS apps

webkit gives you auto-escaping templates, signed sessions, and security middleware on top of std.web - one language from HTTP handler to HTML.

webkit batteries · std.web router · ai in the handler

Webhook receivers and async handlers

Fast-start HTTP servers, typed parsing of provider payloads, and background work via channels - verify the signature, enqueue, respond 200.

Respond then process · Typed event structs · ecko dev reload

JSON API backends

std.web routes returning http.json, capability-granted packages per domain, and mock-mode tests for every endpoint shape.

JSON first · Modular grants · Test without HTTP

Static site generation

This site is the case study: build.ecko renders every page to dist/, Cloudflare serves bytes - no Node, no bundler, no runtime in production.

Generator is an Ecko program · No production runtime · Docs from Markdown

CLI tools

Commands your team actually installs and keeps

Ecko use cases