NoLiMa [0] and "context rot" [1] would indicate that with a ~165k request, Opus 200k would suck, and Opus 1M would be better (as a lower percentage of the context window was used)... but they are the same model, right? However, there are practical inference deployment differences that could change the whole paradigm, right? I am so confused.

Anthropic says it's the same model [2]. But, Claude Code's own source treats them as distinct variants with separate routing [3]. Closest test I found [4] asserts they're identical below 200K but it never actually A/B tests, correct?

Inside Claude Code it's probably not testable, right? According to this issue [5], the CLI is non-deterministic for identical inputs, and agent sessions branch on tool-use. Would need a clean API-level test.

The API level test is what I really want to know for the Claude based features in my own apps. Is there a real benchmark for this?

I have reached the limits of my understanding on this problem. If what I am trying to say makes any sense, any help would be greatly appreciated.

If anyone could help me ask the question better, that would also be appreciated.

[0] https://arxiv.org/abs/2502.05167

[1] https://research.trychroma.com/context-rot

[2] https://claude.com/blog/1m-context-ga

[3] https://github.com/anthropics/claude-code/issues/35545

[4] https://www.claudecodecamp.com/p/claude-code-1m-context-window

[5] https://github.com/anthropics/claude-code/issues/3370