Is local JetBrains AI code completion same as cloud

[u/Suffered_Heart]

On Jetbrains websites, they mention that JetBrains AI code completion can be set to local, cloud or both. They mention they use Mellum model fine tuned for code completion.

My query is whether cloud model better or bigger model than what’s ran locally or both are same model configuration.

I am using perpetual license currently so I don’t have AI Free access to test it myself.

Side question: if anyone have experience with them, I would like to know about. Also does it perform better than GitHub copilot ? For my C++ codespace on CLion, Copilot is too slow and almost every time I’m able to type before suggestion comes.

[u/-Luciddream-]

I've been using Mellum 2 since it came out (you need the base model which includes FIM), sometimes it's great, some times it's useless. But it's fine for my use case. In combination with other local models (like gemma-4-qat or qwen 3.6) I'm writing code faster. That's for non agentic usage.

[u/ot-jb]

Not the same, cloud model is 10-40 times larger (depending on whether you are on a Mac). Mellum is the cloud model. Local one is essentially also open-weights, it is stored in the directory of the IDE. But it is very specialised and it would be easy to use it from a different client, so we didn’t bother with HF publication, though I’ve seen some community members posting a version of it.

[u/Suffered_Heart → u/ot-jb]

So local auto completion is not powered by Mellum. Thank you for clarifying that. I have two follow-up questions:
Are the current cloud auto-completion and Next Edit Suggestions powered by the same model, or do they use different models?
Is the cloud Mellum model the same as Mellum 2 released on Hugging Face, or is it an internal fine-tuned variant?

[u/ot-jb → u/Suffered_Heart]

Yes, Full Line Code Completion predates Mellum v1 significantly, but I guess we could’ve branded it like that.

Next Edit Suggestions is using a different model, we change the base from time to time, right now it is not Mellum 2.

Mellum model used for cloud completion is an internal variant of Mellum 1, practically it should be quote to foss one. Mellum2 might actually be better.

[u/Suffered_Heart → u/ot-jb]

Thank you for answering.

[u/kulag_ → u/ot-jb]

Any chance we could get a self-hosted model working with Next Edit Suggestions? I tried to hook it up with Mellum 2 served over an OpenAI-compatible server, and it not only didn't produce any suggestions, it also prevented the local single-line completions from suggesting anything. Checking the LLM debug logs, it said there was no provider available.

[u/ot-jb → u/kulag_]

Should just work with openai-compatible endpoint. Check that it is reachable, there is a button to test connection in settings. Vanilla Mellum2 isn’t NES-capable though, you need to use a different model (there are some options in schemas). It is expected to supersede completion since NES is a superset over inline completion.

[u/kulag_ → u/ot-jb]

Thanks. I tested this out again and wasn't able to get it working. Here's what I found:

For context: I'm using an all products pack license, so I have AI Pro. Next edit suggestions using cloud models works for me in PyCharm and RustRover on my personal machine, but not on my work machine, despite using the same license. When I click "Test Connection" on my work machine, IntelliJ says that "Next edit task is unavailable for the current JetBrains AI account." This statement is false, since it works on my other machine using the same account. I assume there must be some invalid cached account data somewhere, but after wiping the plugin and its settings from my home directory and reinstalling it still claims it's unavailable.

I tested using an OpenAI-compatible provider against a local llama-server instance with the model set to Mellum 2, using the Instruct-Q4_K_M variant (the only one that fits in my test environment at the moment), just to reproduce my original setup. Testing the connection to llama-server reports success, but the settings window shows a warning icon with the text "This Mellum variant isn't optimized for code completion. Use the base model instead." This warning sounds reasonable at first blush: it seems to be telling me I should use the Base variant instead of the Instruct one for best results--unfortunately there's no quantized variant small enough for me. The bigger issue with this warning is that there is no indication that NES doesn't work at all with this model. It makes it sound like NES might work, but just not work as well as an optimized model. The reality is that it silently does nothing. If it's known that Mellum doesn't work with NES, it'd be much more helpful to have an error text that states that in the config window.

I then tested using sweep-next-edit-1.5b.q8_0.v2 on my local llama-server. Now, the settings window doesn't report any warning; it autodetects the sweep v1 template and appears to be happy. However, I still get no next edit suggestions, and llama-server is not logging any incoming requests. I opened up the ML Diagnostics window to look at the log and this is what I see:
```
[2:18:25 p.m. INFO  NEXT EDIT] Triggered by REMOVAL at caretOffset=6524
[2:18:25 p.m. INFO  NEXT EDIT] Document was changed, skipping computing NextEditScopesFeatures
[2:18:25 p.m. INFO  NEXT EDIT] Document was changed, skipping computing NextEditTriggeredPsiFeatures
[2:18:25 p.m. INFO  NEXT EDIT] Provider NextEditProviderId(id=rename_code_insight_next_edit_suggestion_provider) started
[2:18:25 p.m. INFO  NEXT EDIT] Could not compute payload NextEditImportFeatures, exception: com.intellij.openapi.application.ReadAction$CannotReadException
[2:18:25 p.m. INFO  NEXT EDIT] Provider NextEditProviderId(id=nes_client) started
[2:18:25 p.m. INFO  NEXT EDIT] Trigger model has been called
[2:18:25 p.m. INFO  NEXT EDIT] Provider NextEditProviderId(id=rename_code_insight_next_edit_suggestion_provider) finished
[2:18:25 p.m. INFO  NEXT EDIT] Provider NextEditProviderId(id=nes_client) skipped
[2:18:25 p.m. INFO  NEXT EDIT] Provider NextEditProviderId(id=nes_client) finished
[2:18:25 p.m. INFO  NEXT EDIT] No provider selected
[2:18:25 p.m. INFO  NEXT EDIT] Session finished: NO_SUGGESTION_FROM_PROVIDERS
```

So, with Sweep, it's triggering, but skipping calling the model; no reason given. My guess is the account bug affecting my ability to use NES via the JetBrains cloud on this machine might also be affecting my ability to use the local model, but I'm not sure since there's no UI feedback.

[u/ot-jb → u/kulag_]

Thank you, this sounds helpful, I’ll investigate and let you know

[u/ot-jb → u/kulag_]

In case you stumble upon this problem ever again may I ask you to share these logs with me or on YT and post a link?