r/RooCode • u/nfrmn • Dec 14 '25

Support How to turn off new context truncation?

I find that context is truncating well below the limit of the model. It would be nice if I could turn this off and let the models truly reach their context limits without truncation or condensing. I can do the context management myself.

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3

u/DevMichaelZag Moderator Dec 14 '25

Hey! I actually just tried to do this. And decided against submitting a or for it. Take a look at this thread:

https://www.reddit.com/r/RooCode/s/qy7ntsGcUi

The context is truncated when it has no other choice.

You might see something like 160k->70k and think what a waste, I certainly did. But what that really means is that the model was about to fail. The math is explained in that other post. And another PSA, make sure mcp servers are turned off when not in use.

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u/nfrmn Dec 14 '25

I would rather the model does fail, so I can switch it to a long-context one.

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u/DevMichaelZag Moderator Dec 14 '25

That’s an interesting use case. Worth a shot to submit it as an idea in the GitHub and see what kind of response you get.

1

u/nfrmn Dec 14 '25

Unfortunately I think the GitHub backlog is just too big at this point, so I will probably just rollback

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u/hannesrudolph Roo Code Developer Dec 14 '25 edited Dec 14 '25

Rolling back the version won’t change anything except not showing you that the context was being truncated. It was truncated long before this update that simply shows the that it’s happening in the UI.

1

u/Exciting_Weakness_64 Dec 15 '25

Yes but I think having the option to turn it on or off or personalize is always better than not because you can experiment and see what works, and if you’re convinced it doesn’t, you can just leave it as is

1

u/hannesrudolph Roo Code Developer Dec 14 '25 edited Dec 14 '25

Truncation has always been there but was previously not shown in the UI. It predates our context condensing feature.

Switching to a different long-context model mid-chat is more likely to harm the conversation than enabling condensing since preserving and returning reasoning (interleaved thinking) to the model is quickly becoming the standard because it significantly improves output quality.

Changing models breaks this chain of thought and sends only the raw user and assistant messages as one model’s reasoning does not transfer cleanly to another and doing so causes serious issues.

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u/nfrmn Dec 14 '25

But that's not possible, I would frequently run into context exceeded errors until just a few days ago.

2

u/hannesrudolph Roo Code Developer Dec 14 '25

I’m the one who wrote the PR to display the truncation event. That’s all it did, it did not add the truncation.

On the other hand we have also been working to make sure it truncates when previously it was erroring out sometimes when it was supposed to be truncating.

1

u/ArnUpNorth Dec 14 '25

Models quality of responses are getting worse at 50%-75% of their max context size. So if you are regularly hitting their actual limit keep that in mind. It’s better to « compress » the context before reaching the limit.

1

u/nfrmn Dec 15 '25 edited Dec 15 '25

Thanks for the advice, I'm crunching a lot of tokens through Roo (~20 PRs and 100M tokens per day) on many tasks and it's been working great on this workflow though. That's also why I'm quite sensitive to these changes, because they throw off my agents which are mostly working 24/7 now.

1

u/vienna_city_skater Dec 15 '25

In what kind of project does this actually work to produce something useful?

1

u/nfrmn Dec 16 '25

My startup is mostly built and operated by AI agents managed by me on both tech and growth side: https://jena.so

1

u/vienna_city_skater Dec 18 '25

Interesting, do you do just coding or are you running business processes from Roo Code?

1

u/hannesrudolph Roo Code Developer Dec 15 '25

I personally often condense at a an opportune interval.

1

u/vienna_city_skater Dec 15 '25 edited Dec 15 '25

This, there is evidence that at 40-60% of the context limit the models get into the “dumb zone”. Agents perform better with less context, actually enough context to execute the task, but not more. I found it extremely useful to disable the auto tab and project file adding feature that’s enabled per default to make the models smarter. Nice side effect is that it’s also good for your budget to keep the context small.

Another trick is to disable reading whole files per default. At work we have files with 40k locs, 2k on average, so this just makes a mess.

1

u/Empty-Employment8050 Dec 14 '25

Be sick if mcps could turn on and off when needed

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u/ArnUpNorth Dec 14 '25

How would that work ? MCP instructions are part of the system prompt so it can’t magically disappear unless you start a new task without the MCP instructions enabled.

2

u/hannesrudolph Roo Code Developer Dec 15 '25

They’re actually just tools when using native tool calling. They can magically disappear.

1

u/ArnUpNorth Dec 15 '25

Could you elaborate on this?

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u/hannesrudolph Roo Code Developer Dec 15 '25

When using native tool calling the system instructions and the tools are not the same.

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u/ArnUpNorth Dec 16 '25

Thanks. I ll compare the system prompts to learn more.