[Feature]: Add Hermes Agent as a provider via ACP (minimal, Grok-shaped)

[raman325]

Summary

Add a built-in driver for Hermes Agent (https://github.com/NousResearch/hermes-agent) over ACP, in the same shape as the Grok driver (#2809): a thin HermesAcpSupport + driver on the generic ACP runtime in apps/server/src/provider/acp/, a HermesSettings schema (enabled, binaryPath), a builtInDrivers.ts registration, and focused tests. No contract changes, no client changes, no new transport, no migrations.

Hermes ships a standard ACP server (hermes acp, protocolVersion 1) in current releases (hermes acp --check passes on v0.21), so packages/effect-acp and the generic ACP runtime should apply directly — the per-agent code is the small driver + support/probe layer, exactly like Grok and Cursor.

Why

There is visible demand for Hermes here (see the comment section on #4604), but the attempts so far all went big and stalled:

• feat: add Hermes-powered T3 Work #4604 (+38k lines) builds an entire "T3 Work" product surface and is stacked on an unmerged draft
• feat: Hermes gateway provider — agent instances, Home threads, and first-class agent UX #4678 (+35k lines, closed) added a bespoke reverse-WebSocket gateway transport
• feat(server): add experimental Hermes ACP provider #8929 (+1k lines, closed by its author) was ACP-based but hand-rolled its own adapter rather than reusing the generic runtime

This proposal is deliberately the opposite: the smallest diff that makes Hermes selectable, mirroring what already merged for Grok.

Scope fences

• Local binary only, spawned per session like the other providers. No remote-Hermes support in v1.
• Models: report what Hermes's ACP surface advertises; otherwise a single default entry (Hermes manages its own model config).
• No MCP credential forwarding, no session import, no Hermes-specific UI. Generic unknown-driver rendering in the hosted clients already covers display.
• Text generation (titles/commits/branches): included only if it slots cleanly into the existing helper pattern; otherwise explicitly marked unsupported.

Offer

I run Hermes self-hosted and will build this in my fork regardless. If a PR in this shape is something you would consider, I will keep it Grok-template-faithful (~driver + settings + tests + one doc page) with verification evidence per CONTRIBUTING. If it is not wanted upstream, no hard feelings — the fork path works.

[juliusmarminge]

Closing as a duplicate of #6951, the earlier proposal for local Hermes ACP support without a gateway or T3 Work. It already tracks the small-driver versus shared-ACP design choice.