Add heartbeat telemetry support

docs/beta-test-plans.md

@@ -7,12 +7,13 @@ beta on that server.
 ## Game reporter protocol
 
 Send JSON to `POST /api/telemetry` with `Content-Type: application/json`.
-There are exactly three events. Send them whether or not a beta is active.
+There are four events. Send them whether or not a beta is active.
 
 | Event | Fields |
 | --- | --- |
 | `game_start` | `server`, `map`, `players` with each player's `name` and `guid` |
 | `round_change` | `server`, `map`, `round`, `players` with each player's `name`, `guid`, `kills`, `headshots`, `downs`, `revives`, and `score` |
+| `heartbeat` | Same fields as `round_change`; sent periodically during a round to refresh the current round and player stats |
 | `game_end` | `server`, `map`, `round`, `players` with each player's `name`, `guid`, `kills`, `headshots`, `downs`, `revives`, and `score` |
 
 `server` is the exact registered Electric Cherry server name. `map` is the
@@ -92,7 +93,7 @@ of beta activity. That page documents cumulative stat accounting, round credit,
 and the limits of identifying matches from this protocol.
 
 The game scripts are uploaded artifacts, not source maintained in this
-repository. Their reporter should emit the three payloads above.
+repository. Their reporter should emit the four payloads above.
 
 ### Telemetry diagnostics
 
@@ -138,7 +139,7 @@ Requirements on a qualifying server are ANDed:
 
 | Requirement | Evidence |
 | --- | --- |
-| Reach round X | A round change or game end reports round >= X with the required player count |
+| Reach round X | A round change, heartbeat, or game end reports round >= X with the required player count |
 | Complete qualifying matches | Game end, optionally qualified by round, player count, and duration |
 | Populated minutes | Time between consecutive game reports with enough players at both ends |
 | Player-hours | Populated minutes multiplied by the lower reported player count, divided by 60 |