Mallard

Subsystems & limits

The pieces of the script API that aren't a trigger, a ctx property, or a function on their own: outbound HTTP, the two configuration stores, caching, Twitch, how failures propagate, and the numeric budgets every tier enforces.

fetch()

The only network access scripts have; full signature on Script functions. HTTPS-only by default (HTTP is allowed only when the env record has fetch_allow_http set), standard ports only, GET/POST/PUT/PATCH/DELETE/HEAD only, private/internal addresses are blocked (SSRF-guarded), and responses are auto-decompressed. A 5s default timeout, up to 15s via optionsJson.timeoutMs, and a 1 MB response cap (post-decompression). Request bodies are capped at 64 KB.

The allowed request headers are accept, content-type, authorization, user-agent, client-id, api-key, anthropic-version, and any x-* header; anything else is dropped.

Two separate limits apply per guild: 30 requests/minute (a flat sliding window, same on every tier) and an hourly call budget that scales by tier (5/15/30/60 on Free/Plus/Pro/Ultra; see the tier table below), exposed live as ctx.fetchCallsRemaining so a data-dependent loop can size itself against what's left.

Environment variables

Guild-level configuration lives in a single key-value record with the key env, whose value is a JSON object edited as one blob on the Database page. Its keys are exposed to every script as ctx.env.* (e.g. {"mod_log_channel_id":"123"} becomes ctx.env.mod_log_channel_id), read-only during execution. Every value is a string; non-string JSON values are stringified when read.

Secrets

Sensitive values like API keys live in a separate secrets record that only guild administrators can view or edit; mods with script access cannot. Scripts never receive the real values: each key is exposed as an opaque placeholder token {{secret:NAME}} via ctx.secret.*, and the real value is substituted server-side only inside fetch() (in the URL, header values, or body). Use it directly, e.g. authorization: "Bearer " + ctx.secret.MyKey. A key is present only once an admin sets a non-empty value, so if (ctx.secret.MyKey) tests whether it's configured. Because a script only ever holds the placeholder, logging it, sending it in a message, or throwing it can never leak the real secret.

Key-value store

Each guild has its own key-value store (getKV/setKV/deleteKV) with optional per-entry expiry, browsable and editable as JSON on the Database page. env and secrets are reserved system keys: getKV/setKV/deleteKV all fail closed on them (a script-visible error), so they can only be read through ctx.env/ctx.secret and edited on the Database page.

Writes persist immediately. A setKV call lands in the database the instant it returns, so a value it wrote survives even if the script errors or times out later in the same run (see Error handling). Total storage per guild is capped by tier (5/15/50/100 MB; see the table below); a write that would exceed the cap throws.

Message cache

An in-memory cache of every message seen in the last 30 minutes, scoped per guild and per channel. It's used to recover best-effort deleted-message content on the MessageDelete trigger, and to read a message's previous content on MessageUpdate (Discord's edit event only carries the new version). getMessage() and getMessages() do not read it; they fetch live from Discord over REST (each counting as one rate-limited action), so they return complete, authoritative history rather than only what the bot recently saw. Being in-memory, a bot restart empties it, so a deleted/edited message right after a restart has no recoverable content.

Twitch

Link a Twitch channel on the General page to enable the TwitchStreamOnline, TwitchStreamOffline, and TwitchChannelUpdate triggers. Just entering the broadcaster's channel name is enough, no authorization needed. Those three dispatch immediately, fanned out to every guild following that broadcaster with a matching enabled script.

TwitchChatBatch additionally needs a chat-reader authorization from the streamer or one of their moderators. Chat is buffered per guild (up to 1,000 messages per window; once full, the oldest plain message is dropped to make room; redemptions and bit cheers are only evicted if literally everything buffered is one of those. The drop count is reported as ctx.twitch.messagesDropped) and flushed as one execution every ~10 minutes via ctx.twitch.messages, never per message, so it can't burn through the hourly execution budget. Nightbot's messages are filtered out before they reach a script. A channel-point text redemption arrives as a normal chat message with rewardId set, and a bit cheer with bits set, which is how redemption/cheer flows (e.g. a shoutout command) are scripted without needing broadcaster-only scopes.

Status chips (Pending / Active / Error / Reauthorize Required / Not Connected) on the General page reflect the current connection state; a revoked authorization or a reader losing mod status flips the status and is cleaned up automatically within about a minute.

Error handling & guild isolation

Actions run live, in call order, the moment a script calls them. There's no queue and no all-or-nothing rollback. A script that errors, times out, or exhausts a budget partway keeps every action, KV write, and fetch it already made, and all of it counts against the hourly budgets regardless of how the run ended. This is why work that must happen later (lifting a temp ban, a reminder) is logged as intent to the KV store and swept periodically by a Scheduled script, rather than the script trying to "wait."

A failed Discord action normally throws and ends the script with an Error status. The one exception is a target that simply isn't reachable: a user who doesn't accept DMs, a member who already left, a message already deleted. Those outcomes are outside a script's control, so sendDm, kick, timeout, unban, and deleteMessage return false instead of throwing, and the script keeps going (the REST call still counts against the hourly action budget). ban is deliberately excluded from this list. Discord allows banning a non-member fine, so a 404 there means a genuinely bad user ID. Everything else still throws: a bad snowflake, a missing permission, an exhausted budget, a target in another guild.

Every action a script takes is scoped to its own guild: channel-targeting functions validate the target actually belongs to the executing script's guild before acting, so a script cannot read or modify another server no matter what ID it's given.

Tiers & limits

Every tier includes the entire scripting engine: every trigger, function, and integration, from the start. What scales with tier is per-guild hourly budget and storage. Tiers are per guild, bought through Discord's store, and both upgrades and downgrades take effect immediately. Full pricing detail is on /pricing.

LimitFreePlusProUltra
Price / month$0$2.99$5.99$14.99
Script executions / hour2,0005,00015,00030,000
Discord actions / hour501005001,000
fetch() calls / hour5153060
Runtime budget / hour60s120s250s500s
Key-value storage5 MB15 MB50 MB100 MB
Max script length5,000 chars10,000 chars15,000 chars30,000 chars
Min scheduled interval30 min15 min10 min5 min

Every cap above except the executions row is a rolling one-hour budget, checked live per call and exposed to the running script (ctx.fetchCallsRemaining, ctx.restActionsRemaining) so a data-dependent loop can size itself against what's left. Usage against every cap is shown on the guild's General page.

The executions row is a runaway/database-row backstop, not a budget to plan around. It's set well clear of normal traffic. Runtime and Discord actions are what actually bind first for a busy guild.

Two tier-independent, non-configurable backstops sit underneath all of this: Jint (the JS engine) enforces a 30-second wall-clock timeout per execution, a 50-level recursion limit, and a 100,000-statement cap. These protect the process itself regardless of tier, since one process can't offer unbounded wall-clock time no matter what a guild is paying for. Separately, Discord's own command-registration limits apply to every tier alike: 32-character command/option names, 100-character descriptions, and 25 options per command.

An unhandled error has occurred. Reload 🗙