## Summary
Buzz has no way to load-test the relay as a whole. `wamp_bench` sends
kind:9 messages from one identity to one channel, and
`perf/relay_bus_scaling.py` only measures Redis fan-out. Neither can
show what happens to a relay with many more users, channels, or deep
threads.
This PR adds `buzz-loadgen`, a load generator in
`crates/buzz-test-client`:
- `buzz-loadgen seed <scenario.toml>` creates communities (through `POST
/operator/communities`), channels, channel history, and deep threads.
- `buzz-loadgen run <scenario.toml>` drives simulated humans and agents
through ramp steps (1x, 2x, ...) and prints p50/p90/p99 latency, errors,
and rate-limit rejections per operation for each step.
- Humans hold a WebSocket with live subscriptions, fetch history on
connect, and send presence, typing, messages, thread replies, and
reactions. Agents authenticate with a NIP-OA tag, poll HTTP `/query`,
post through HTTP `/events`, and send encrypted observer frames to their
owner.
- Per-client rates come from the scenario. Set them to model a
deployment, and a step of `users = 10` means 10x that deployment's
population.
- Every identity, host, and channel id comes from the scenario's
`run_id`, so `--shard i/n` splits a population across machines with no
coordination.
- Each step measures from ramp start to hold end, so connect failures
during the ramp count. A step aborts the run when an operation's error
rate or p99 (delivery included) crosses the scenario's `[abort]` limits,
when a relay `CLOSED`s a live subscription often enough, or when a
client exits unexpectedly. The report names the limit that tripped.
- Each connect plus authentication has a deadline
(`target.connect_timeout_secs`), and shutdown is bounded, so a relay
that stalls connections still produces a report and a non-zero exit.
- `seed` exits non-zero unless the relay accepted every planned post.
- `NostrWsConnection::connect_to_addr` opens the TCP connection to a
given address while the URL still names the host. This lets a client
inside the relay's cluster reach a community host through the relay's
service address.
- `wamp_bench` is deleted. Its paced single-channel load is a subset of
a scenario.
What got simpler: one load tool instead of two partial ones. The change
touches only test tooling, the unit-test lane, and one additive method
in `buzz-ws-client`. Relay code is unchanged.
### Related issue
None found.
### Testing
Smoke run on a Linux workstation against a local relay built from this
branch, with its own Postgres, Redis, and MinIO containers:
```bash
cargo run --release -p buzz-test-client --bin buzz-loadgen -- seed perf/scenarios/local-smoke.toml
cargo run --release -p buzz-test-client --bin buzz-loadgen -- run perf/scenarios/local-smoke.toml
```
- `seed`: 710 of 710 posts accepted (10 channels, 200 history messages,
10 thread roots, 500 thread replies).
- `run`: both steps (1x = 50 humans + 5 agents, then 2x) completed with
0 errors and 0 rate-limit rejections. Every operation recorded traffic:
55/55 connect/auth, 205/205 live subscriptions, 150 history fetches,
presence/typing/observer frames, messages and reactions, HTTP `/query`,
HTTP `/events`, and publish→delivery. Delivery p99 was 45 ms at 1x and
42 ms at 2x.
- Failure paths are covered by unit tests: a listener that accepts TCP
but never answers (connect deadline, then `run` aborts and returns), a
fake `/events` server that rejects posts (`seed` fails), `CLOSED`
subscriptions, and invalid scenarios.
`just test-unit` (and its `scripts/run-tests.sh` fallback) now runs the
new `loadgen::` unit tests. Before this change, no CI lane ran
`buzz-test-client` lib tests.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Signed-off-by: Luke Tornquist <tornquist@squareup.com>
Co-authored-by: Elrond <28d6302a099e5225b02c4155ac4236e4912603df2ab08dbfc2f4fef08ce598c8@buzz.block.builderlab.xyz>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
