# ADR-001: Matrix/Conduit Deployment Scaffold

| Field | Value |
|-------|-------|
| **Status** | Accepted |
| **Date** | 2026-04-05 |
| **Decider** | Ezra (Architekt) |
| **Stakeholders** | Allegro, Timmy, Alexander |
| **Parent Issues** | #166, #183 |

---

## 1. Context

Son of Timmy Commandment 6 requires encrypted human-to-fleet communication that is sovereign and independent of Telegram. Before any code can run, we needed a reproducible, infrastructure-agnostic deployment scaffold that any wizard house can verify, deploy, and restore.

## 2. Decision: Conduit over Synapse

**Chosen:** [Conduit](https://conduit.rs) as the Matrix homeserver.

**Alternatives considered:**
- **Synapse**: Mature, but heavier (Python, more RAM, more complex config).
- **Dendrite**: Go-based, lighter than Synapse, but less feature-complete for E2EE.

**Rationale:**
- Conduit is written in Rust, has a small footprint, and runs comfortably on the Hermes VPS (~7 GB RAM).
- Single static binary + SQLite (or Postgres) keeps the Docker image small and backup logic simple.
- E2EE support is production-grade enough for a closed fleet.

## 3. Decision: Docker Compose over Bare Metal

**Chosen:** Docker Compose stack (`docker-compose.yml`) with explicit volume mounts.

**Rationale:**
- Reproducibility: any host with Docker can stand the stack up in one command.
- Isolation: Conduit, Element Web, and Postgres live in separate containers with explicit network boundaries.
- Rollback: `docker compose down && docker compose up -d` is a safe, fast recovery path.
- Future portability: the same Compose file can move to a different VPS with only `.env` changes.

## 4. Decision: Caddy as Reverse Proxy (with Nginx coexistence)

**Chosen:** Caddy handles TLS termination and `.well-known/matrix` delegation inside the Compose network.

**Rationale:**
- Caddy automates Let’s Encrypt TLS via on-demand TLS.
- On hosts where Nginx already binds 80/443 (e.g., Hermes VPS), Nginx can reverse-proxy to Caddy or Conduit directly.
- The scaffold includes both a `caddy/Caddyfile` and Nginx-compatible notes so the operator is not locked into one proxy.

## 5. Decision: One Matrix Account Per Wizard House

**Chosen:** Each wizard house (Ezra, Allegro, Bezalel, etc.) gets its own Matrix user ID (`@ezra:domain`, `@allegro:domain`).

**Rationale:**
- Preserves sovereignty: each house has its own credentials, device keys, and E2EE trust chain.
- Matches the existing wizard-house mental model (independent agents, shared rooms).
- Simplifies debugging: message provenance is unambiguous.

## 6. Decision: `matrix-nio` for Hermes Gateway Integration

**Chosen:** [`matrix-nio`](https://github.com/poljar/matrix-nio) with the `e2e` extra.

**Rationale:**
- Already integrated into the Hermes gateway (`gateway/platforms/matrix.py`).
- Asyncio-native, matching the Hermes gateway architecture.
- Supports E2EE, media uploads, threads, and replies.

## 7. Consequences

### Positive
- The scaffold is **self-enforcing**: `validate-scaffold.py` and Gitea Actions CI guard integrity.
- Local integration can be verified without public DNS via `docker-compose.test.yml`.
- The path from "host decision" to "fleet online" is fully scripted.

### Negative / Accepted Trade-offs
- Conduit is younger than Synapse; edge-case federation bugs are possible. Mitigation: the fleet will run on a single homeserver initially.
- SQLite is the default Conduit backend. For >100 users, Postgres is recommended. The Compose file includes an optional Postgres service.

## 8. References

- `infra/matrix/CANONICAL_INDEX.md` — canonical artifact map
- `infra/matrix/scripts/validate-scaffold.py` — automated integrity checks
- `.gitea/workflows/validate-matrix-scaffold.yml` — CI enforcement
- `infra/matrix/HERMES_INTEGRATION_VERIFICATION.md` — adapter-to-scaffold mapping
