session-source-fork

1# session_source Fork
2 
3`session_source` is a **member-level OpenRig field** that declares how a
4newly-launched managed seat should derive its initial conversation
5continuity from a prior runtime conversation source.
6 
7v1 supports one mode: **`fork`** — start a *new* managed seat from a
8prior native runtime conversation source without claiming the original
9seat continued.
10 
11The schema is runtime-neutral; implementation is runtime-specific (Claude
12and Codex have their own native fork commands).
13 
14## Use this when
15 
16- Authoring a rig spec member that should fork from a prior session
17- Authoring a `rig expand` payload with `session_source`
18- Reasoning about whether to use `fork` vs `rebuild` vs `resume` vs `fresh` for a new seat
19- Composing fork + handover (seat-handover-over-fork) — see `seat-continuity-and-handover` skill
20 
21## Don't use this when
22 
23- The seat is being **restored**, not created. Restore continues an existing managed seat. Fork creates a new seat.
24- The continuity is **artifact-backed mental-model rebuild** (packet-derived understanding, not native runtime continuity). Use `mode: rebuild` (see `seat-continuity-and-handover` for the rebuild surface) — do NOT collapse fork into artifact-backed reentry; the distinction is load-bearing.
25- The runtime is `terminal`. Terminal runtime rejects `session_source`.
26 
27## The shape (canonical YAML)
28 
29```yaml
30members:
31  - id: reviewer-2
32    runtime: claude-code        # or "codex"; not valid on terminal
33…