Managed ACP sessions show base prompt as title in Codex (and other harness UIs) #2334

Summary

Codex (and likely other ACP harness UIs) labels sessions from the start of the injected prompt. Managed Buzz agents all begin with the same base section:

[Base]
You are operating inside the Buzz platform — a Nostr-…

So the Codex session list shows many identical rows that look like truncated system text, not the Buzz agent display name (e.g. Fizz, Varys).

Buzz already has a real name (kind:0 display_name / agent settings). That name is not passed through as a session/thread title for the underlying runtime.

Repro

1. Run one or more managed agents on the Codex ACP runtime.
2. Open Codex session history / sidebar (desktop or CLI resume UI).
3. Observe entries titled with [Base] You are operating inside the Buzz platform… instead of the agent name.

Root cause

buzz-acp frames platform context as [Base] / [System] / [Workspace] for session/new and legacy user messages (framed_system_prompt / prepend_base_for_legacy in crates/buzz-acp/src/pool.rs; body from crates/buzz-acp/src/base_prompt.md).

Codex appears to use the first prompt content as the human-visible session title. Every Buzz-managed Codex process shares that opener, so titles collide.

Scope / non-goals

• Do not rewrite or remove the base prompt text for models just to fix UI chrome.
• Do not fold this into agent rename/profile sync only (Agent rename: relay profile sync failure is silently swallowed with no user feedback #1822, Agent rename does not notify running agents: AGENTS.md update invisible mid-session #1823).
• Related but separate from model self-ID in multi-agent threads ([Bug] ACP harness does not inject agent identity into system prompt — agents can drift to wrong persona under thread context pressure #2287). Fixing identity in the system prompt helps the LLM; it does not by itself fix Codex session list labels.

Suggested direction

1. Canonical label from Buzz: agent display_name, optionally with harness and/or channel (e.g. Fizz or Fizz · Codex).
2. Per-runtime adapter in buzz-acp (or desktop spawn) that sets title/name where that runtime supports it.
3. Codex first: find the codex-acp / ACP hook for session title or metadata; if none, a short first user-visible title line must not break prompt framing for desktop observers that split [Base] / [System].
4. Same product goal for Claude, Goose, OpenCode, Grok, etc.; each needs its own integration point.

Acceptance

• Codex session list shows a stable, human-readable Buzz agent name (or name + harness), not the base-prompt prefix.
• Base prompt content for the model is unchanged in substance.
• Desktop observer / transcript section parsing still works if framing changes.
• Document the pattern so other harnesses can follow.

Related

• [Bug] ACP harness does not inject agent identity into system prompt — agents can drift to wrong persona under thread context pressure #2287 — identity not injected into system prompt (model-facing)
• Agent rename: relay profile sync failure is silently swallowed with no user feedback #1822 / Agent rename does not notify running agents: AGENTS.md update invisible mid-session #1823 — rename / profile sync (Buzz-side display name plumbing)