> The subagent approach is structurally different from the others because it runs with clean context.

Yes, and this is what I mean by "which context the prompt runs in". The subagent approach is different and has pros and cons, and it may in some situations be better (but perhaps not in others). On the other hand, I can also just create a new conversation and paste my own review prompt into it; then take the last turn's summary output and feed it back into my main conversation thread in the unusual event I would need to do so. Spawning a subagent is a convenient shortcut for this, but ultimately, it's the same thing.

> I think the intent behind 'install a language server plugin' is that these tools should lint automatically after every edit, without waiting for an explicit call from the LLM.

This is a great point and I had only checked my session logs for explicit tool calls. I went back and looked for diagnostics injected automatically by the harness after every edit, and whether the agent made use of them.

Claude: neither the Rust or Dart LSPs ever inserted any diagnostic events, but Ty did. Across 627 sessions, ty-lsp injected diagnostics blocks in 186 sessions, with a total of 33 findings. Out of those 33, 32 were dismissed as unrelated (13) or pre-existing (19). Only 1 finding was acted upon. The model is in the habit of running the batch analysis tools (ruff, ty, cargo clippy etc.) and prek anyway, so it would have caught that diagnostic regardless.

Codex: no diagnostic events were inserted by any of the LSPs.

So I won't be reinstalling those LSPs.