From 6019a39efa2bf1ff371a064e35bfd68520cccffc Mon Sep 17 00:00:00 2001
From: Teknium <127238744+teknium1@users.noreply.github.com>
Date: Wed, 9 Sep 2026 10:18:08 -0700
Subject: [PATCH] fix(discord): raise default upload preflight to 20 MiB (Sep 3
 2026 API change)

Discord raised the default file upload limit from 10 MiB to 20 MiB for
users, bots, webhooks and interaction responses (developer changelog,
Sep 3 2026). The 25 MiB constant here predates the preflight salvage and
never matched the platform; more importantly discord.py 2.7.1 still
reports 10 MiB via guild.filesize_limit for unboosted guilds, so the
guild-aware path under-reported the cap and rejected 10-20 MiB files
Discord now accepts. Floor the guild value at the platform default so a
stale library constant can only widen, never shrink, the preflight.
---
 plugins/platforms/discord/adapter.py | 15 +++++++++++----
 tests/gateway/test_discord_send.py   |  6 ++++++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/plugins/platforms/discord/adapter.py b/plugins/platforms/discord/adapter.py
index e0beb39b29..93419755a1 100644
--- a/plugins/platforms/discord/adapter.py
+++ b/plugins/platforms/discord/adapter.py
@@ -171,9 +171,12 @@ _DISCORD_SELECT_MAX_ROWS = 5
 _DISCORD_MODEL_SELECT_CAPACITY = (_DISCORD_SELECT_MAX_ROWS - 2) * _DISCORD_SELECT_MAX_OPTIONS
 _DISCORD_BUTTON_LABEL_LIMIT = 80
 # Default Discord attachment cap for DMs / channels without a guild boost
-# context. Guild channels expose the effective limit via
-# ``guild.filesize_limit`` (boost tier may raise it). See issue #50846.
-_DISCORD_DEFAULT_UPLOAD_LIMIT_BYTES = 25 * 1024 * 1024
+# context. 20 MiB since the Sep 3 2026 API change (10 MiB before); guild
+# channels expose a boost-raised limit via ``guild.filesize_limit``, but
+# discord.py's fallback constant can lag the platform default, so the
+# effective limit is never taken below this floor. See issue #50846 and
+# https://docs.discord.com/developers/change-log (Sep 3, 2026).
+_DISCORD_DEFAULT_UPLOAD_LIMIT_BYTES = 20 * 1024 * 1024
 _DISCORD_ELLIPSIS = "\u2026"
 _DISCORD_NONCONVERSATIONAL_METADATA_KEYS = frozenset({
     "non_conversational", "non_conversational_history",
@@ -3167,12 +3170,16 @@ class DiscordAdapter(DiscordMediaMixin, BasePlatformAdapter):
 
         Prefer the guild's boost-aware ``filesize_limit`` when present; fall
         back to the platform default for DMs / group DMs without a guild.
+        The guild value is floored at the platform default: discord.py's
+        unboosted-tier constant can lag a platform-wide raise (10 MiB in
+        2.7.1 vs the 20 MiB default since Sep 3 2026), and under-reporting
+        makes the preflight reject files Discord would accept.
         """
         guild = getattr(channel, "guild", None)
         if guild is not None:
             limit = getattr(guild, "filesize_limit", None)
             if isinstance(limit, int) and limit > 0:
-                return limit
+                return max(limit, _DISCORD_DEFAULT_UPLOAD_LIMIT_BYTES)
         return _DISCORD_DEFAULT_UPLOAD_LIMIT_BYTES
 
     async def play_tts(self, chat_id: str, audio_path: str, **kwargs) -> SendResult:
diff --git a/tests/gateway/test_discord_send.py b/tests/gateway/test_discord_send.py
index 97964899ae..00bfc3131c 100644
--- a/tests/gateway/test_discord_send.py
+++ b/tests/gateway/test_discord_send.py
@@ -436,10 +436,16 @@ def test_discord_upload_limit_uses_guild_filesize_limit():
     guild_channel = SimpleNamespace(guild=SimpleNamespace(filesize_limit=50 * 1024 * 1024))
     dm_channel = SimpleNamespace(guild=None)
     no_limit_guild = SimpleNamespace(guild=SimpleNamespace(filesize_limit=0))
+    # Stale library constant (discord.py 2.7.1 reports 10 MiB for unboosted
+    # guilds; the platform default is 20 MiB since Sep 3 2026) must not lower
+    # the preflight below the platform default.
+    stale_guild = SimpleNamespace(
+        guild=SimpleNamespace(filesize_limit=_DISCORD_DEFAULT_UPLOAD_LIMIT_BYTES // 2))
 
     assert DiscordAdapter._discord_upload_limit_bytes(guild_channel) == 50 * 1024 * 1024
     assert DiscordAdapter._discord_upload_limit_bytes(dm_channel) == _DISCORD_DEFAULT_UPLOAD_LIMIT_BYTES
     assert DiscordAdapter._discord_upload_limit_bytes(no_limit_guild) == _DISCORD_DEFAULT_UPLOAD_LIMIT_BYTES
+    assert DiscordAdapter._discord_upload_limit_bytes(stale_guild) == _DISCORD_DEFAULT_UPLOAD_LIMIT_BYTES
 
 
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