docs(prd): 0070 add the slice roadmap incl. consolidated sidecar (#352)

Enumerate the implementation slices in the Sequencing section: dev-harness
core, launch+broker, docker broker, consolidated per-host sidecar (new),
then firecracker and macOS. Slices 1-4 implemented (#352/#356/#357/#358).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck

docs/prds/0070-per-host-orchestrator.md

@@ -325,18 +325,31 @@ orchestrator becomes a VM. Decouple the two risks instead:
   secret handling) is proven with fast iteration — *then* wrap that exact
   service in the VM and solve wiring separately.
 
-Backend order (cheapest proof → hardest → last):
+### Slices
 
-1. **Docker orchestrator** — nearly free (the sidecar bundle is already
-   containers; collapse N bundles into one persistent container). Proves
-   consolidation + the `BottleBackend` seam with the least moving parts.
-2. **Firecracker orchestrator** — the real work: the shim + VM-to-VM
+Built bottom-up as a stack of small PRs off this one (status: **1–4
+implemented** in #352 → #356 → #357 → #358):
+
+1. **Dev-harness core** ✅ — SQLite registry (runtime state) + fail-closed
+   attribution (source IP + identity token) + the HTTP control plane.
+2. **Launch lifecycle + broker contract** ✅ — `launch_bottle` /
+   `teardown_bottle` + the signed, structured `LaunchBroker` request
+   (HS256 JWT, static ids/flags only, provenance-verified, fail-closed),
+   with a stub broker for the harness and registry rollback on failure.
+3. **Docker launch broker** ✅ — the first real broker: `docker run` / `rm`
+   per bottle, built only from the request's static fields; proves the
+   `BottleBackend` seam on the cheapest backend.
+4. **Consolidated per-host sidecar** ✅ — one persistent sidecar shared by
+   all bottles (idempotent singleton) instead of one per bottle — the core
+   consolidation win, source-IP-keyed via the attribution invariant.
+5. **Firecracker broker + sidecar** — the real work: the shim + VM-to-VM
    routing (host forwards `bbfcN` → orchestrator TAP; the nft table grows
-   forward rules where today it drops all non-DNAT egress). Built against
-   the dev-harness so the app logic is already proven.
-3. **macOS (Apple container)** — last (container-to-container networking).
+   forward rules where today it drops all non-DNAT egress), against the
+   already-proven dev-harness.
+6. **macOS (Apple container)** — last (container-to-container networking).
 
-Keep the sidecar **service one shared thing** throughout.
+Backends land cheapest-first (docker → firecracker → macOS); keep the
+sidecar **service one shared thing** throughout.
 
 ## Non-goals