Add 'pi researcher' capability to assistant

[gergology]

I would like the assistant to incorporate 'pi researcher' as an additional capability alongside the current 'Claude researcher'. Please implement this new researcher integration.

[gregology]

Hey, couple things I want to clarify before jumping into this:

1. What do you mean by "pi researcher"? Is this Perplexity AI, Pi from Inflection, or something else? Need to know which API we're targeting.

2. Re: "Claude researcher" - the current research capability in the codebase is actually assistant-gemini (Gemini-based web research). Is that what you're referring to, or did you have a separate Claude-powered researcher in mind?

Once I know what service we're talking about I can spec out the integration pretty quickly - the manifest + service handler pattern already supports this kind of thing.

Developer metrics

Total duration: 3m 2s
Turns: 43
Tool calls: 40
Tokens: 97,379 input / 1,244 output

Stage	Model	Duration	Turns	Tool calls	Tokens (in/out)	Cache read	Cache creation
triage	claude-opus-4-6	2m 50s	42	39	55,883 / 1,041	35,905	19,974
comment_draft	claude-opus-4-6	0m 12s	1	1	41,496 / 203	20,637	20,856