f765fc2b27
LEARNING.md indexes ten concept-to-file pointers (the spec floor was five) — the newtype pattern, exhaustive enum match, sans-IO, trait extension seams, thiserror + hot-path match-and-continue, Arc<Mutex> vs Arc<RwLock>, DashMap, str0m's single-mutation invariant, graceful shutdown, include_str!. fuzz/README.md pre-paves the layout (no hostile-bytes surface in slice 1; harnesses land at step 5 per the out-of-scope table). README's new dev-loop section documents the libopus FFI prerequisite and the manual e2e steps.
166 lines
8.5 KiB
Markdown
166 lines
8.5 KiB
Markdown
# Rutster
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The open-source engine for building the **AI-era contact center** — self-hostable, AI-native,
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memory-safe Rust. A spiritual successor to Asterisk's *place in the world*, not its protocols
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or its architecture.
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> Not a port of Asterisk. rutster inherits the role Asterisk held — *the self-hostable engine a
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> technical builder uses to stand up a contact center* — and re-aims it at a category AI is
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> actively disrupting, instead of a PBX category UCaaS already ate.
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## Slice 1 dev loop (WebRTC media loopback)
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> Build prerequisite: install libopus (the `opus` crate links it via FFI):
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> ```bash
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> sudo apt-get install -y libopus-dev # Debian/Ubuntu
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> # Fedora: sudo dnf install -y opus-devel
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> # macOS: brew install opus
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> ```
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> This is the one system dependency in slice 1. Opus is FFI per PORT_PLAN
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> §7's "🦀 Core (FFI)" disposition — the codec surface Rust doesn't need
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> to re-implement.
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Run the server:
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```bash
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cargo run
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# listening on http://0.0.0.0:8080
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```
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Open a browser to `http://localhost:8080/`, click "Start call", grant
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microphone permission. Speak — you should hear yourself back within
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~200 ms (no perceptible delay). Click "Hang up" to tear down; server
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logs `Closing → Closed`.
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Verbose tracing:
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```bash
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RUST_LOG=rutster=debug cargo run
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```
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### Slice 1 "done" checklist (spec §6.5)
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On a clean checkout:
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1. `cargo test --all` passes.
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2. `cargo fmt --check` passes.
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3. `cargo clippy -- -D warnings` passes.
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4. `cargo deny check` passes.
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5. `cargo run` + browser manual e2e: speak → hear echo within ~200 ms.
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6. Hang-up button triggers `Closing → Closed` in server logs.
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7. Every stub crate compiles; its doc-comment names its scheduled step.
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8. `LEARNING.md` indexes at least 5 "to learn X, read Y" pointers.
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## Why it exists
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Asterisk won because contact centers were **built on it** (Vicidial, GOautodial, a thousand
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integrator builds) — it never tried to *be* Five9. rutster inherits that position: it is a
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**framework / engine, not a turnkey product**.
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The white space no incumbent fills:
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| Competitor | What they are | rutster's edge |
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| **LiveKit** | Horizontal real-time media infra (Go) | rutster owns the **contact-center domain** (ACD, IVR, queues, recording, CDR, dialer, supervisor) LiveKit will never ship |
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| **Cloud CCaaS** (Five9, Genesys, NICE, Amazon Connect, Twilio Flex) | Proprietary, AI bolted on | Self-hostable, AI-**native**, no per-seat/minute lock-in |
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| **Cloud AI-voice** (Vapi, Retell, Bland) | Cheap managed voice bots | You own your **calls and training data**; it's a *contact center* (escalation, queues), not a single bot |
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| **Dated OSS** (Vicidial, FreePBX) | Self-hostable, Asterisk-era | Modern, AI-native, memory-safe Rust |
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The wedge is a **coherent combination, not a silver bullet**:
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1. **No-GC real-time determinism** — tight turn-taking / barge-in / jitter in a no-GC loop.
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2. **One secure auditable boundary** — trunk termination + media + spend/abuse control + audit in
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a single memory-safe trust domain. One thing to certify (strongest for PCI / HIPAA / TCPA).
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3. **Operational simplicity** — one binary, one bill, one deploy.
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**Honest caveat:** the agent *brain* (STT/LLM/TTS) is necessarily external — audio leaves the box
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to reach it, same as LiveKit. The real-time edge therefore lives in the **local reflexes that don't
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need the brain** (VAD killing TTS the instant the caller speaks, barge-in, jitter, pacing, DTMF),
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not the brain round-trip. The moat is the *whole*.
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## Who it's for
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The modern equivalent of the 2006 Linux-nerd-who-stood-up-Asterisk-for-an-SMB: the
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**CLI/IDE/AI-comfortable self-hosting technical builder** — runs Claude Code in a terminal, lives
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in an editor with an AI pair, versions everything in git, self-hosts on principle. *Not* the no-code
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admin clicking a flow-designer canvas. The builder serves the non-technical operator downstream,
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exactly as integrators did on top of Asterisk.
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## What it is / isn't
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- **Is:** a Rust media core owning the **per-call vertical** (trunk SIP termination + RTP/SRTP media
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+ local real-time reflexes + a clean audio tap to an external brain + in-boundary spend/abuse
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control); a programmable call model exposed as a REST/gRPC API + event stream; WebRTC-first human
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ingress; a library of contact-center capabilities (ACD, IVR, queues, recording, CDR, dialer,
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supervisor) delivered as services around the core.
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- **Isn't:** a TDM/PSTN-hardware PBX. No DAHDI, no Sangoma/Digium cards, no ISDN/SS7, no
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IAX2/H.323/SCCP/MGCP/Unistim. PSTN reach is via SIP trunks only. Inbound SIP *endpoint*
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registration (desk phones) is deferred to an out-of-tree edge adapter — not the browser/SSO UX
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rutster targets.
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## Core design pillars
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1. **Memory-safe by construction** — Rust everywhere on the hot path; fuzzed sans-IO protocol
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parsers. Hostile bytes hit a fuzzed Rust parser first. Eliminates the buffer-overflow/RCE CVE
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class — and, with the C SBC edge dropped, this is *literally true at the wire*.
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2. **Security-as-product** — the single auditable boundary *is* the moat. TLS/SRTP mandatory,
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deny-by-default routing, built-in toll-fraud controls, mTLS gRPC admin (no plaintext AMI), hard
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multi-tenancy. Compliance is a buying criterion, not a row.
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3. **In-boundary spend / abuse control** — spend caps and abuse/pacing control live **inside the
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trust boundary**, co-located with trunk termination. A runaway brain can't exceed pacing or
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spend because it doesn't hold the wire — structurally impossible for a 3-vendor stack.
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4. **Data ownership** — calls and training data never leave the operator's infra. The self-host
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wedge *and* the fuel for the ML self-improvement loop.
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5. **Degradation, deterministic, observable** — no-GC real-time loop; OpenTelemetry traces that
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follow a single call across the boundary; config-as-data, not `.conf` files edited on a box.
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6. **Operational simplicity** — one binary, one bus, one deploy (`compose up`).
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## Layout
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- [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) — the fused per-call vertical + composable
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horizontal platform; the agent tap as the central interface.
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- [`docs/PORT_PLAN.md`](docs/PORT_PLAN.md) — the capability *checklist* (what a telephony system
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must handle), *not* an architecture template. Every Asterisk subsystem mapped to a disposition
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with rationale.
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- [`docs/adr/`](docs/adr/) — decisions. Highlights:
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- [0002](docs/adr/0002-north-star-and-fused-core.md) — north star + fused vertical
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- [0003](docs/adr/0003-sip-rust-native-trunk.md) — Rust-native trunk SIP (no SBC shield)
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- [0004](docs/adr/0004-license.md) — GPL-3.0-or-later
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- [0005](docs/adr/0005-event-bus.md) — Valkey (bus + state store)
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- [0006](docs/adr/0006-ingress-posture.md) — WebRTC-first ingress; SIP endpoint deferred
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## Status
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Scoping. No code yet — the [vision revision](docs/superpowers/specs/2026-06-26-vision-revision-design.md)
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and ADRs define the architecture; the workspace will be scaffolded from the capability ladder
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and the thin-slice first proof.
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## First proof (the spearhead)
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The full thin slice, sequenced so each step is its own proof — never a big bang:
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1. **WebRTC media loopback** (terminate RTP/SRTP, echo audio to a browser) — proves the media core
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2. **Add the tap** (route audio to an external echo process and back) — proves the tap interface
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3. **Swap echo for the brain** (ideally a single speech-to-speech API, e.g. OpenAI Realtime, to
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collapse STT+LLM+TTS into one integration) — proves agent integration
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4. **Add barge-in** (VAD-driven playout kill) — proves the reflex
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5. **Replace WebRTC ingress with a real PSTN trunk call** — proves the trunk client
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6. **Add the spend cap** (hard-stop at threshold) — proves the boundary
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Steps 1–4 *are* the reflex loop — the hard, most-differentiating part proves itself before trunk
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integration piles on. "I called my Rust box and an AI answered the phone" is the momentum fuel a
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solo multi-year build needs.
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## Capability ladder (the grand vision, incrementally)
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| Rung | Capability | Reuses |
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| 1 | **Self-serve** — AI answers, contains the call | the thin-slice first proof |
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| 2 | **Escalation** — human agent barges in / takes over when AI breaks down | the audiohook/barge primitive |
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| 3 | **Measurement** — containment rate, where/why AI failed | CDR + analytics on calls *you own* |
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| 4 | **Self-improvement** — every takeover → auto-labeled training data → loop | rungs 1–3 compounding |
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## License
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**GPL-3.0-or-later** ([ADR-0004](docs/adr/0004-license.md)). Strong copyleft in the Asterisk lineage,
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modernized one notch. The license is the *floor*, not the moat — the wedge is.
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