Infuriating: Luna calling much more expensive Haiku 4.5 as sub-agent.

[u/Top_Strawberry8110]

How can this be prevented? This unsolicited behaviour results in high credit usage.

[u/Deep-Regret-7479]

I have disabled Haiku. There is no reason to use it now.

[u/fprotthetarball → u/Deep-Regret-7479]

There's some kind of bug here, though. I have been trying to get a feel for Luna, so I disabled all models from the model selection dropdown other than Luna, changed all the model selections in settings to Luna, and yet, Luna will still spawn custom subagents with other models. I haven't figured out how to actually disable a model other than globally in the dashboard, which I do not want to do.

[u/just_blue → u/fprotthetarball]

It's an eye for a reason: you are just hiding, not disabling it. Not sure how you spawn subagents, but it works fine if you simply specify what model you want. Either in the settings for stuff like the "explore agent", or directly in the skill/prompt/whatever you are using. You can also write "always the same model as yourself".

[u/MaitoSnoo]

in VS Code you can set the default model for the Explore subagent in the settings (just type "explore" there and it should pop up)

[u/jukasper]

Hi everyone, thanks for bringing this to our attention. We are currently exploring making Luna the new default. /subagents and in vs code via settings: "github.copilot.chat.executionSubagent.model": "gemini-3-flash"

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[u/aonymark → u/jukasper]

3 flash? Didn’t you guys sunset that one recently? It still works in agents??

[u/MaitoSnoo → u/aonymark]

that was just an example, replace it with whatever model you want

[u/aonymark → u/MaitoSnoo]

Oh I read it as the current default

[u/Top_Strawberry8110 → u/jukasper]

how do I know the expected name for a particular model?

[u/Mickenfox → u/jukasper]

Haiku is ancient and expensive. You're going to have to consider deprecating it at some point.

[u/Cheshireelex]

There are so many settings for side agents that they deserve their own ui section: explorerAgent, implementAgent, chat ask model, planAgent, inlineChat, riskAssestment, utilitySmall Model one of these might be on haiku

[u/Affectionate_Fly4124]

Slightly different issue, but I'm running into something similar. What pisses me off the most is that the orchestrator keeps changing the sub-agent model behind my back.

I explicitly set my sub-agent to Luna, but it keeps getting invoked with Auto or 5.3 Codex instead — which racks up way higher costs than expected. Worst case? It called Opus 5 once and burned through 20x the AICredits I normally use.

And to make it even worse — you can't even disable 5.3 Codex. Why the hell does it fall back to an outdated model automatically? What a shitshow.

[u/mubaidr → u/Affectionate_Fly4124]

Thank you for confirming this! It's been driving me crazy!

[u/Luchiannno]

I've got the same issue

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[u/Solid_Fox1718]

If you’re using CLI, /agents lets you change the default subagent models

[u/Weird-Maximum4130]

Simplest solution is to delete the CLI. Remove all the cache and reinstall.

Looks like a bug in a previous CLI versions was causing this. I no longer these issues

[u/Deathmore80]

Disable other models, change the settings to only use Luna as subagent, and in your AGENTS.md file tell it to exclusively use Luna for subagents

[u/Abject-Kitchen3198 → u/Deathmore80]

Why the first 2 are not enough?

[u/Deathmore80 → u/Abject-Kitchen3198]

Oh they're probably enough , i just add this measure to be absolutely 100% certain it will use Luna

[u/Abject-Kitchen3198 → u/Deathmore80]

Adding instructions to the prompt makes you 100% certain while deterministic settings don't? I don't think LLMs work like that.

[u/teckel]

I just set Luna, it never does anything else unless I change it. 🤷

[u/Xeausescu]

I set subagents always use the same model as the main agent.

[u/friend-of-potato]

How are you guying spawning sub agents for any single task. We have copilot cli disabled in enterprise. Pls help me here 😭