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>

schema/config.schema.json

@@ -189,10 +189,22 @@
           "maximum": 9007199254740991
         },
         "bash_timeout": {
-          "description": "Seconds a bash command may run (default 120).",
+          "description": "Seconds a bash command may run in the foreground before it goes on in the background as a job (default 120).",
           "type": "number",
           "exclusiveMinimum": 0
         },
+        "jobs": {
+          "description": "Background commands one session may have running at once (default 8).",
+          "type": "integer",
+          "exclusiveMinimum": 0,
+          "maximum": 9007199254740991
+        },
+        "subagent_steps": {
+          "description": "Most model steps in one subagent run (default 50) — a runaway backstop, not a budget.",
+          "type": "integer",
+          "exclusiveMinimum": 0,
+          "maximum": 9007199254740991
+        },
         "wall_seconds": {
           "description": "Budget for one prompt: seconds of work, not counting time spent waiting for you. Past it the model answers from what it has. Unset: none.",
           "type": "number",