# Mercury Composable

> A Java framework for building composable, event-driven applications from self-contained
> functions wired by YAML event flows. Functions couple only through named routes and event
> envelopes, so orchestration is configuration, not code. It runs on Java 21 virtual threads
> (synchronous RPC performs like reactive) and ascends three layers: an event-driven core
> (Platform Core), composable orchestration (Event Script), and a semantic layer where an
> Active Knowledge Graph *is* the application.

> This file is the machine-readable map of the documentation, organized by layer, to help an
> AI agent (or a human) jump directly to the right page.

## Start here
- [Home](https://accenture.github.io/mercury-composable/): the three-layer model and where to go next.
- [Getting Started](https://accenture.github.io/mercury-composable/guides/getting-started/): a working app in five minutes (quickstart), then how a request flows through flows, functions, and REST.
- [AI Developer Guide](https://accenture.github.io/mercury-composable/guides/ai-developer-guide/): **start here if you are an AI agent** — brownfield orientation, layer-choice decision tree, adding features, testing, and pointers to each layer's DSL guide.

## Layer 1 — Event-driven foundation (Platform Core)
- [Architecture Overview](https://accenture.github.io/mercury-composable/guides/architecture/): layers, components, the in-memory event bus, threading, core APIs.
- [Methodology](https://accenture.github.io/mercury-composable/guides/methodology/): the four composable design principles.
- [Event-driven Foundation](https://accenture.github.io/mercury-composable/guides/event-driven/): Layer 1 overview — functions, route names, PostOffice, EventEnvelope, the in-memory event bus.
- [Write your first function](https://accenture.github.io/mercury-composable/guides/event-driven/write-your-first-function/): step-by-step — define a function, expose it over HTTP, call it via PostOffice, test it.
- [Function Execution Strategies](https://accenture.github.io/mercury-composable/guides/event-driven/function-execution/): virtual vs. kernel threads, Mono/Flux.
- [Function AI agent guide](https://accenture.github.io/mercury-composable/guides/event-driven/ai-agent-guide/): @PreLoad annotation contract, TypedLambdaFunction interface, pre-write checklist, PostOffice patterns — for deterministic function generation.
- [REST Automation](https://accenture.github.io/mercury-composable/guides/rest-automation/): declare HTTP endpoints via rest.yaml, no controllers.

## Layer 2 — Composable orchestration (Event Script)
- [Composable Orchestration (Overview)](https://accenture.github.io/mercury-composable/guides/event-script/): Layer 2 overview — what Event Script is, the flow mental model, where it sits.
- [Event Script Syntax](https://accenture.github.io/mercury-composable/guides/event-script/syntax/): the flow DSL — structure, task types, data mapping.
- [Flow Configuration Schema](https://accenture.github.io/mercury-composable/guides/flow-schema-reference/): precise flow YAML field reference.
- [Build, Test and Deploy](https://accenture.github.io/mercury-composable/guides/build-test-deploy/): entry point, unit tests, packaging.

## Layer 3 — Semantic (Active Knowledge Graph)
- [Knowledge Graph as Application](https://accenture.github.io/mercury-composable/guides/knowledge-graph/): the paradigm, execution model, node model, built-in skills, layer integration, Playground & AI companion, and maturity.
- [Minimalist Property Graph](https://accenture.github.io/mercury-composable/guides/knowledge-graph/property-graph/): the in-memory property-graph data model and API the layer builds on.

## Operate & integrate
- [Spring Boot Integration](https://accenture.github.io/mercury-composable/guides/spring-boot/): run Mercury as a Spring Boot 3/4 app.
- [Event over HTTP](https://accenture.github.io/mercury-composable/guides/event-over-http/): cross-instance event communication.
- [Minimalist Service Mesh](https://accenture.github.io/mercury-composable/guides/service-mesh/): Kafka-based service discovery and routing.

## Reference
- [API Overview](https://accenture.github.io/mercury-composable/guides/api-overview/): PostOffice, Platform, EventEnvelope, configuration APIs.
- [Annotations Reference](https://accenture.github.io/mercury-composable/guides/annotations-reference/): @PreLoad, @MainApplication, and the rest.
- [Configuration Reference](https://accenture.github.io/mercury-composable/guides/configuration-reference/): application.properties / application.yml keys.
- [Event Envelope Reference](https://accenture.github.io/mercury-composable/guides/event-envelope-reference/): the EventEnvelope and PostOffice API.
- [Reserved Names & Headers](https://accenture.github.io/mercury-composable/guides/reserved-names-and-headers/): system-reserved routes and headers.
- [Actuators & HTTP Client](https://accenture.github.io/mercury-composable/guides/actuators-and-http-client/): built-in actuator endpoints and the AsyncHttpRequest API.
- [Architecture Decision Records](https://accenture.github.io/mercury-composable/arch-decisions/ADR/): the durable architecture decisions (decoupled functions, virtual-thread engine, Map/PoJo I/O, the three paradigm layers, one-atom-four-roles) with their rationale.