Unified cache interface for EDA.

This module provides a simple API for accessing cached Discord data. Data is automatically cached as events are received from the Gateway.

Examples

# Get a guild
guild = EDA.Cache.get_guild("123456789")

# Get a user
user = EDA.Cache.get_user("987654321")

# Get a channel
channel = EDA.Cache.get_channel("111222333")

# Get the bot user
me = EDA.Cache.me()

Storage backend

Where entities live is pluggable; which ones are kept and how many is not. The admission policy, the size limit and eviction, and the telemetry all sit above the backend, so any adapter inherits them:

config :eda, cache_adapter: EDA.Cache.Adapter.ETS   # default
config :eda, cache_adapter: EDA.Cache.Adapter.NoOp  # store nothing

A backend only answers "where does this live", so it never has to reimplement the filtering or the memory bounds. See EDA.Cache.Adapter to write your own.

Obfuscated channels

From 2026-11-16 Discord redacts channels the bot cannot view rather than hiding them: they are still dispatched over the gateway, with name set to "___hidden___", sensitive fields nulled, and the CHANNEL_OBFUSCATED flag set. Before that date the behaviour is opt-in via config :eda, capabilities: [:channel_obfuscation].

EDA caches them like any other channel. They are dropped neither on write nor on read, because "this channel exists and I cannot see it" is real information — Discord explicitly expects apps that manage channels or compute permissions across a guild to detect them and surface that state. Hiding them in the cache would make a channel that demonstrably exists look absent.

Redaction nulls the sensitive fields rather than omitting them, which matters here: EDA.Cache.Channel.update/2 merges the incoming payload over the cached one, so a channel that becomes obfuscated has its name, topic, status and last_message_id genuinely replaced — the previously cached values do not survive. Verified against a live guild on 2026-09-19. Redaction is also selective: position, parent_id, nsfw, bitrate and rate_limit_per_user keep their real values.

The consequences are therefore yours to handle:

• channels/0 and channels_for_guild/1 include them — reject with EDA.Channel.obfuscated?/1 before showing a channel list to a user;

• their permission_overwrites hold a single synthetic @everyone VIEW_CHANNEL deny. EDA.Permission.in_channel/3 already refuses to compute from it and returns {:error, :channel_obfuscated}, so that path is safe;

• a cache admission policy can drop them if you would rather not see them at all:

  config :eda,
    cache: [
      channels: [policy: fn _entity, _key, channel ->
        if EDA.Channel.obfuscated?(channel), do: :skip, else: :cache
      end]
    ]