fluxer/fluxer_docs/src/content/docs/http-api/experiments.mdx

---
# SPDX-License-Identifier: AGPL-3.0-or-later
title: Experiments
description: The experiment assignments envelope, the revalidation and polling contract, and the experiments this server defines.
---

import RouteHeader from '@/components/RouteHeader.astro';

An experiment is an instance-wide rollout that an operator configures. For each account, Fluxer works out from that configuration whether the account is in the rollout and which settings the account receives. The single route on this page resolves every experiment the server defines and returns them in one envelope, together with the polling cadence they share. This server defines `voice_noise_suppression`, whose placement protocol [Voice](/voice/) defines, and `screen_share_delivery`.

Every assignment is advice. A client that ignores one behaves as it does with the rollout off, and no route and no Gateway event reports what a client actually ran.

## Experiment assignments object

One resolution of every defined experiment against one account. Every field is present on every response.

### Structure

| Field | Type | Description |
| --- | --- | --- |
| poll_interval_seconds | integer | Seconds to wait before revalidating, from 60 through 86400 |
| poll_jitter_percent | integer | The largest random offset added to or subtracted from the wait, as a percentage of the wait, from 0 through 50 |
| assignments | [assignment map](#assignment-map-object) object | One entry for each experiment the server defines |

Every account on the instance receives the same `poll_interval_seconds` and `poll_jitter_percent`. One request refreshes every experiment.

## Assignment map object

One entry per experiment. The envelope reports this object even when it is empty.

### Structure

| Field | Type | Description |
| --- | --- | --- |
| voice_noise_suppression? | [noise suppression assignment](#noise-suppression-assignment-object) object | The caller's noise suppression assignment |
| screen_share_delivery? | [screen share delivery assignment](#screen-share-delivery-assignment-object) object | The caller's screen share delivery assignment |

Ignore unknown experiments and treat a missing experiment as off.

This server version writes `voice_noise_suppression` on every response, including while a rollout is disabled. The disabled value is the first [resolution outcome](#resolution-outcomes) below, which reports `enabled` false and the stored `config_version`, so a client that compares `config_version` with the value from its previous response can see that an operator saved the configuration, even while the rollout stays disabled, and needs no second request for it.

## Noise suppression backends

Noise suppression runs in the client, on the microphone track, before that track is published. Fluxer processes no audio for it. The registry is closed, and a backend outside it is not a value this API produces or accepts.

| Value | Description |
| --- | --- |
| none | No processing |
| standard | The browser or platform suppressor the client already has |
| gate | A noise gate keyed on input level |
| speex | The Speex preprocessor |
| rnnoise | The RNNoise recurrent model |
| gtcrn | The GTCRN model |
| deep_filter | The DeepFilterNet model |

A client MUST treat a backend absent from `enabled_backends` as unavailable, including one named by `backend` or by a [guild override](#noise-suppression-guild-override-object).

## Noise suppression assignment object

One resolution of the instance noise suppression rollout against one account. Every field is present whenever the key is written.

### Structure

| Field | Type | Description |
| --- | --- | --- |
| enabled | boolean | Whether the rollout is running on this instance |
| config_version | integer | The revision of the instance configuration this assignment was resolved from |
| user_targeted | boolean | Whether the caller is inside the rollout |
| backend | ?string | The [backend](#noise-suppression-backends) the caller applies, and null where the caller is not targeted |
| source | ?string | Which rule targeted the caller, one of `user_rule` or `canary`, and null where the caller is not targeted |
| guild_overrides | array[[guild override](#noise-suppression-guild-override-object) object] | Per-guild backend replacements that apply to the caller |
| enabled_backends | array[string] | The [backends](#noise-suppression-backends) the client MAY run |
| allow_user_override | boolean | Whether the account's own stored choice replaces `backend` |
| suppression_strength | integer | Suppression strength from 0 through 100, which only a backend that reads it applies |

`config_version` identifies the configuration revision. It can change without changing the caller's assignment.

### Resolution outcomes

The outcomes below set `user_targeted` to false, and they differ in what else they report.

1. The rollout is off. `enabled` is false, `enabled_backends` and `guild_overrides` are empty, and `allow_user_override` is false.
2. The operator has excluded the caller. `enabled` is true, and every other field is as in the first outcome.
3. The caller was not drawn. `enabled` is true, and `enabled_backends`, `guild_overrides`, and `allow_user_override` all hold their configured values.

A caller is drawn either by the operator's allowlist, which sets `source` to `user_rule`, or by the sampled share of the account population, which sets `source` to `canary`. A caller that is drawn while `backend` is absent from `enabled_backends` is reported as not drawn, with `user_targeted` false and both `backend` and `source` null.

A client branches on `user_targeted` rather than on `enabled_backends`, because the third outcome keeps the array populated. A `guild_overrides` entry applies in its guild whether or not the caller was drawn.

`config_version` reports the stored revision in all outcomes, the rollout being off included.

## Noise suppression guild override object

One backend replacement scoped to one guild. While the caller is connected to a voice channel of that guild, the override's `backend` replaces the assignment's `backend`.

### Structure

| Field | Type | Description |
| --- | --- | --- |
| guild_id | snowflake | The guild the replacement applies in |
| backend | string | The [backend](#noise-suppression-backends) to run in that guild |

An override naming a backend that is absent from `enabled_backends` is dropped before the response is written, so every entry is runnable.

## Screen share delivery assignment object

One resolution of the instance screen share delivery rollout against one account. The field is present whenever the key is written.

### Structure

| Field | Type | Description |
| --- | --- | --- |
| enabled | boolean | Whether the caller runs the reworked screen share delivery path |

A caller is drawn either by the operator's allowlist or by the sampled share of the account population. `enabled` is false in every other case, the rollout being off included.

## Get experiment assignments

<RouteHeader method="GET" path="/v1/experiments" bot />

Resolves every defined experiment for the caller and returns an [experiment assignments](#experiment-assignments-object) object. The response is derived per account, so it is never shared between accounts.

### Response body

[Experiment assignments](#experiment-assignments-object) object.

### Response

| Status | Body | Condition |
| --- | --- | --- |
| 200 | response body | The envelope was resolved |
| 304 | empty | The request sent a matching `If-None-Match` |

### Request headers

| Field | Type | Description |
| --- | --- | --- |
| If-None-Match? | string | An `ETag` from an earlier response to this route |

A client sends the `ETag` it last received. Fluxer compares it against the tag of the envelope it just resolved and answers 304 with no body on a match. `*` matches any current tag. A weak comparison is used, so a `W/` prefix on either side does not defeat the match.

### Response headers

| Field | Type | Description |
| --- | --- | --- |
| ETag | string | A strong tag over the envelope body, sent on 200 and on 304 |
| Cache-Control | string | The literal value `private, no-cache` |
| Vary | string | The literal value `Authorization`, replaced by `Origin` where the [cross-origin policy](/http-api/#cross-origin-requests) echoed an allowed origin |

The `ETag` changes when the response changes. Treat it as an opaque value.

`ETag` is listed in `Access-Control-Expose-Headers` and `If-None-Match` in `Access-Control-Allow-Headers`, so a cross-origin client reads the tag and revalidates with it.

### Polling

A client reads this route once per session and then again every `poll_interval_seconds`, offset by a random amount up to `poll_jitter_percent` of that interval in either direction. It sends the last `ETag` on every request after the first. A client MUST NOT poll faster than the lower end of that jitter range.

Until the first successful response, use 300 seconds with 15 percent jitter.

### Rate limit

60 requests per 10 seconds for each authenticated user, on the `default` bucket.