Studio follows the platform rename: product branding F∆I -> Ch∆In in UI strings, command examples fai -> chain, and — critically — the spawned hub binary path ~/.fai/bin/fai -> ~/.fai/bin/chain so Studio launches the renamed binary. The fai_* Dart identifiers (FaiLog, widget files, the generated SDK) stay = vendor/internal namespace. flutter analyze: no issues. Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>
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Architecture in one paragraph
Ch∆In has three concepts you'll meet everywhere: Hub, Module, Flow.
The hub is a single Rust binary called fai. It runs as a
gRPC server, loads modules, executes flows, and writes events
to a SQLite database. One binary, no Docker, no message broker,
no cluster. You can run it on a laptop, a Raspberry Pi, or a
locked-down KRITIS server — same artefact every time.
A module is a small WebAssembly component that does one
thing well. Modules are sandboxed: each one declares the
network endpoints, files, and environment variables it needs,
and the hub enforces that list. A module that doesn't ask for
network access can't reach the network. Modules ship as .fai
bundles with a CycloneDX SBOM and a sigstore signature.
A flow is a YAML file with three top-level keys:
inputs:, steps:, outputs:. Steps run in declared order,
each step calls one module, and outputs from one step can feed
inputs of the next. Flows are deterministic — same inputs
produce the same audit trail.
How the pieces fit
Studio ──gRPC──▶ Hub ──loads──▶ Module (WASM)
│
├──executes──▶ Flow (YAML chain of modules)
│
└──writes────▶ Audit log (hash-chained, in
SQLite; WORM-1 by construction)
What you don't need
- No container runtime. The hub doesn't shell out to Docker or Podman. Modules are WASM components loaded in-process.
- No external database. SQLite ships with the hub.
- No background services. One process; restart with
chain daemon restart— see Doctor → Daemon control.
Where to go next in this app
- Store to discover modules and federated MCP / n8n capabilities, install them in one click.
- Flows to run the sample flows that ship with the hub
(e.g.
extract-summarize). - Audit to see every event the hub recorded — the hash-chained log is the platform's source of truth.