Request Entity Too Large error when using GitHub Copilot model around ~70k tokens

[cesarfr2002]

Description

When using a GitHub Copilot model (Claude Sonnet 4.6) in OpenCode, I consistently get a "Request Entity Too Large" error once the conversation/context reaches approximately 70k tokens.

It seems like the request payload exceeds a limit, possibly due to accumulated conversation history or how the request body is being constructed.

Plugins

none

OpenCode version

1.2.6

Steps to reproduce

1. Select a GitHub Copilot model (Claude Sonnet 4.6).
2. Start a normal conversation and keep interacting.
3. Allow the context to grow (large conversation history).
4. Once the total context reaches approximately ~70k tokens, send another message.
5. The request fails with "Request Entity Too Large".

Screenshot and/or share link

Operating System

Cachyos 6.19.0-2

Terminal

kitty

[github-actions]

This issue might be a duplicate of existing issues related to "Request Entity Too Large" errors. Please check:

• Request entity too large error #6574: Request entity too large error (also occurs with Copilot provider)
• Request Entity Too Large not caught before trying to read large files #8956: Request Entity Too Large not caught before trying to read large files
• 413 Payload Too Large when reading local image (gpt-5.2-codex + opus-4.5) #12060: 413 Payload Too Large when reading local image

These issues share similar symptoms of request payload size limits being exceeded. Please verify if this is a distinct issue or if it relates to one of the above.

[cesarfr2002]

Confirmed this is a duplicate of #6574. Closing.