Harness spec 2.0.0: background work is a job — commands and subagents alike, seen and steered

One registry per process, every job owned by a session: bash's background commands (and a command
still running at its timeout, which now goes to the background instead of being killed) and
subagents started with task background: true. job_list, job_output, job_stop (the former
bash_list, bash_output, bash_kill) and the new job_send and report; a finished job wakes the owning
session in every front end with its marked note. The TUI counts jobs, lists them (/jobs), opens a
command's output, enters a subagent and messages it, moves a command to the background (ctrl+b)
and asks before quitting with jobs running. The link gains the jobs capability. Subagents get a
session row of their own, the spec's preamble and agent texts, and their errors reach the report.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/provider/types.ts

@@ -13,7 +13,7 @@ export type ToolCallPart = { type: "tool_call"; id: string; name: string; args:
 export type Message =
   /** `turnId`: the turn a prompt started, kept with it in the store for
    *  `_lembas/session/history`; never sent to a model. */
-  | { role: "user"; parts: (TextPart | ImagePart)[]; turnId?: string }
+  | { role: "user"; parts: (TextPart | ImagePart)[]; turnId?: string; /** The harness wrote it (a job's note), not the person: shown as such. */ machine?: true }
   | { role: "assistant"; parts: (TextPart | ReasoningPart | ToolCallPart)[] }
   | { role: "tool"; callId: string; name: string; content: string; isError?: boolean }