Herdr connector speaks only the legacy herdr TUI socket API - no herdr-core (hc) support

[corysutyak]

Summary

crates/pa-daemon/src/herdr.rs reports agent state exclusively through the herdr TUI's socket API (pane.report_agent / pane.release_agent, gated on HERDR_ENV / HERDR_PANE_ID / HERDR_SOCKET_PATH).

Herdr has since split into three products: the legacy TUI (herdr 0.9.x), herdr-core (hc, the headless runtime, https://github.com/herdrdev/herdr-core) and herdr-app (the desktop GUI). herdr-core is now the thing that actually runs terminals - including for the desktop app, over SSH, on any machine - and its socket speaks a different JSON-RPC surface (terminal.*; no pane.* methods).

What we measured (herdr-core 0.1.16, prime-agent 0.10.2, Linux x64)

• prime-agent 0.10.2 run inside an hc terminal with HERDR_ENV=1, HERDR_PANE_ID and HERDR_SOCKET_PATH pointing at the core socket: the connector never engages (the core does not answer its method; no herdr lines in the session log).
• Probing the core socket directly with a well-formed pane.report_agent request returns:

{"error":{"code":-32601,"data":{"hint":"see `hc schema`","kind":"unknown_method"},"message":"unknown method \"pane.report_agent\""},"id":"1","jsonrpc":"2.0"}

• Net effect: under herdr-core (which includes every terminal the herdr desktop app starts, local or over SSH), prime-agent never appears as an agent in the app's agents sidebar. The app attributes agents from OSC 7501 reports, which prime-agent does not emit on any version we checked (0.9.4 TS and 0.10.2 Rust).

What would fix it

Any one of these would close the gap:

1. Teach the built-in connector a herdr-core backend: the equivalent state push over hc's JSON-RPC (its hc schema self-describes the API; terminal identity comes from HC_TERMINAL_ID/HC_TERMINAL_SOCKET, which hc already exports to children - the exact analogue of the TUI's HERDR_* trio).
2. And/or emit OSC 7501 status from the TUI (the escape sequence herdr-app parses; ESC ] 7501 ; {"state":"working","app":"prime-agent"} BEL) so the app sees prime-agent with no socket at all.

Happy to test candidates; we run both stacks (herdr-core 0.1.16 on three hosts, prime-agent on a headless build box) and can validate a nightly same-day.

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Environment: prime-agent 0.10.2 (Rust, installed via release tarball), herdr-core 0.1.16, herdr-app 0.1.11, Linux x86_64 / NixOS. Reproduced on two hosts.