# Echolot app

The production Android client ([spec](../docs/)). Native Kotlin + Jetpack Compose. Multi-module;
built bottom-up from a verifiable protocol spine.

## Modules

| Module | Type | Status |
|---|---|---|
| `core-protocol` | pure Kotlin/JVM | **done** — client half of `probe-protocol.md`, verified live against the server |
| `core-measurement` | pure Kotlin/JVM | planned — `measurement-schema.md` types |
| `core-probe` | Android lib | planned — app-tier probes, ported from `echolot-prober` |
| `core-shizuku` | Android lib | planned — dual-path executor (UserService + newProcess fallback) |
| `app` | Android app | planned — Compose UI |

`core-protocol` is deliberately Android-free so it builds and unit-tests on any JDK (no Android
SDK) and can run **integration tests against a live server**.

## core-protocol

Implements the control plane (SPKI-pinned enrollment/profile/sessions via `HttpsURLConnection` —
Android-API-1 compatible, hostname verification off because trust is the pin), the HKDF-SHA256
session-key schedule, and the binary ELT1 UDP data plane (HMAC gate, ECHO + observation block,
MTU probe) — byte-compatible with the Go server.

```sh
./gradlew :core-protocol:test              # unit tests (crypto vectors, wire round-trip)
scripts/test-fmr.sh                         # live end-to-end test against the deployed server
```

`test-fmr.sh` mints an enrollment token over SSH, enrolls via the public control plane, computes
the SPKI pin from the served cert, and runs `LiveServerTest` — proving the client speaks the wire
protocol to the real server (enroll → profile → session → echo+observation → MTU → observations).
The live test self-skips when `ECHOLOT_LIVE_*` env vars are absent, so unit runs and CI stay green
offline.