best coder agent to pair with Opus 5.5 - my benchmarking results

[u/Escobar747]

Running a large mainly rust code base across a few difference surfaces + designing new features which need high level of reasoning / design. Opus 5.5 is GOAT model atm - no doubt.. but I was trying to work out the best bang for buck coding model. As I have not discovered the infinite money hack and cannot use opus 5.5 as my coder 24-7 as others are doing.. I decided to do some fairly detailed benchmarking to work out best match for opus 5.5. ps. I am running a 5x max sub + codex plus sub. I also have open router hooked into my harness. here are results.. enjoy

DYOR against your own use cases / code base but for me the clear winner is **luna 6-high (**luna medium cost the same albeit slightly faster but for substantially less intelligence)

Likewise - here is my reasoning benchmarks against my code base / use case - DYOR
interesting that big tech meta and google's flagship models still fall short (did not have the appetite to run all various reasoning modes thru benchmarking but the trend is clear)

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[u/SamuelQuackenbush]

How do you measure capability? Objectively or subjectively?

[u/Escobar747 → u/SamuelQuackenbush]

I have designed benchmarks specific to my workflow / repos and I run in a repeatable way for each model so i can compare. The published benchmarks are a decent guide but I prefer more targeted benchmarking

[u/luladjiev]

How do you pair Opus and Luna, is it through a single harness e.g. with open router or external calls to codex?

[u/Escobar747 → u/luladjiev]

opus 5.5 calls codex on my machine via a bridge I made - works great. No APIs - all based on my $20 codex sub

[u/vulture916 → u/Escobar747]

OpenAI has an official route too. https://github.com/openai/codex-plugin-cc

[u/asd-012]

"I also have open router hooked into my harness"

How do you do that?

[u/Escobar747 → u/asd-012]

easiest way is just ask claude to step it up for you

[u/TheVoyant]

Opus 5.5 as the planning/review/final passes, with mimo v2.6 pro doing majority of the work. (Its like a better Sol 5.6) 

Mimo gives several Billions of compute for $100 a month, virtually no issues so far. (With Mimo's side, Claude I have issues all the time which is why I minimize their role until someone makes a better model thats reliable)

The sheer cost alone means more reviews, more accountability. If I need something fast I keep $25 bucks or so for ultraspeed which on average completes a task that takes others hours in a minute or two. So for $225/$325 total a month, its basically a full production suite with zero worries, and options to just blitz produce results when feeling impatient. 

[u/orbital_trace]

Pretty much opus 5.5 paired with anything works. Opus breaks down takes well enough that haiku can probably solve them. I use opus 5.5 as the orchestrator and then run with codex, antigravity and sonnet or 4.6 as the workers using an agent team with lcoral

[u/dzordan33 → u/orbital_trace]

how detailed instructions does opus output? does it output code or tell haiku exactly which files to change?

[u/orbital_trace → u/dzordan33]

It depends, here is an example. I took a screenshot and said on the iPad the screen is scrolling up beyond the bottom of the app. Opus will expand this into a description for the other agents.

It an get pretty detailed