feat(ca-sandbox): ship the isolated-sandbox sibling plugin as Feature Forge preview (v0.1.0)

.claude-plugin/marketplace.json

@@ -2,12 +2,16 @@
   "name": "codearbiter",
   "owner": { "name": "arbiterForge" },
   "metadata": {
-    "description": "codeArbiter: an orchestration layer for Claude Code. Single-plugin marketplace."
+    "description": "codeArbiter: a marketplace of two sibling plugins — the ca governance/orchestration layer for Claude Code, plus ca-sandbox, an infrastructure plugin that runs untrusted repos in ephemeral isolated containers."
   },
   "plugins": [
     {
       "name": "ca",
       "source": "./plugins/ca"
+    },
+    {
+      "name": "ca-sandbox",
+      "source": "./plugins/ca-sandbox"
     }
   ]
 }

.codearbiter/CONTEXT.md

@@ -6,21 +6,36 @@ stage: 2
 
 # Project: codeArbiter
 
-The orchestration framework itself. This `.codearbiter/` directory is the v2
+The orchestration framework itself, plus an infrastructure sibling. This repo is a
+**marketplace of two plugins** (ADR-0007): `ca`, the governance/orchestration plugin,
+and `ca-sandbox`, an infrastructure plugin. This `.codearbiter/` directory is the v2
 project-state store — root-level, outside `.claude/`, so it survives even if the
 codeArbiter plugin is uninstalled. The `arbiter: enabled` frontmatter above is the
 single activation flag: it gates both the SessionStart persona injection and the
 arbiter statusline segments.
 
 ## Identity
-A Claude Code plugin that routes work through gated skills and reviewer agents,
-enforces spec-driven TDD and commit gates, decides via SMARTS, and keeps an
-append-only audit trail. Decisive, terse, high-authority.
+Two sibling plugins in one marketplace (ADR-0007):
+
+- **`ca` (governance)** — the kernel. A Claude Code plugin that routes work through
+  gated skills and reviewer agents, enforces spec-driven TDD and commit gates,
+  decides via SMARTS, and keeps an append-only audit trail. Decisive, terse,
+  high-authority. Its identity and gates are unchanged by the sibling.
+- **`ca-sandbox` (infrastructure)** — a locally-hosted GitHub-Codespace equivalent
+  that pulls an untrusted repo into an ephemeral, isolated container (no host-FS
+  access; configurable network), explore, tear down. Infrastructure, not governance —
+  arbiter knows about it and integrates with it, but it is not part of the governance
+  kernel. Independent of `ca`: CI is path-scoped and version bumps are per-plugin.
 
 ## Scope
-Framework source: `ORCHESTRATOR.md`, `skills/`, `commands/`, `agents/`, `hooks/`.
-Project state lives here in `.codearbiter/`.
+- `ca` framework source: `plugins/ca/` — `ORCHESTRATOR.md`, `skills/`, `commands/`,
+  `agents/`, `hooks/`, `tools/`.
+- `ca-sandbox` infrastructure source: `plugins/ca-sandbox/` — `tools/`, `skills/`,
+  `commands/`. Adds host deps (Docker, nixpacks) scoped to this plugin only.
+- Shared project state lives here in `.codearbiter/`.
 
 ## NOT this project
 Not a vendored/multi-platform framework. Not an enterprise compliance suite.
-Claude Code only. Solo developer. See `legacy/ASSESSMENT.md` for the v2 cut list.
+Claude Code only. Solo developer. `ca-sandbox` is the deliberate, recorded
+infrastructure exception (ADR-0007), not a precedent for arbitrary co-location of a
+third plugin. See `legacy/ASSESSMENT.md` for the v2 cut list.

.codearbiter/decisions/0007-second-plugin-ca-sandbox.md

@@ -0,0 +1,58 @@
+---
+status: accepted
+date: 2026-06-20
+title: Host a second sibling plugin (ca-sandbox) in the codeArbiter repo/marketplace
+decided-by: SUaDtL@users.noreply.github.com
+supersedes: none
+governs: .claude-plugin/marketplace.json, .codearbiter/CONTEXT.md, plugins/ca-sandbox/*
+---
+
+# ADR-0007 — Host a second sibling plugin (ca-sandbox) in the codeArbiter repo/marketplace
+
+## Status
+Accepted — ratified 2026-06-20 by SUaDtL@users.noreply.github.com.
+
+## Context
+The 2026-06-20 brainstorm produced `ca-sandbox`: a locally-hosted GitHub-Codespace equivalent that
+pulls an untrusted repo into an ephemeral, isolated container (no host-FS access; configurable
+network). This is **infrastructure**, not governance — it sits at the edge of codeArbiter's stated
+identity. `CONTEXT.md` frames this repo as "the orchestration framework itself" and `marketplace.json`
+describes a "Single-plugin marketplace." Shipping ca-sandbox therefore expands the repo's identity, and
+the maintainer chose to do so rather than spin up a separate repo, because the marketplace `plugins`
+array already supports multiple entries and ca-sandbox integrates tightly with arbiter (its exec seam
+is the natural home for the farm dispatcher's deferred `item-3` process-level sandbox).
+
+## Decision
+codeArbiter's repo and marketplace host a **second, sibling plugin `plugins/ca-sandbox/`**, distinct
+from the `ca` governance plugin. The two plugins are independent: CI is **path-scoped** so that a
+change touching only sandbox paths skips every `ca` check (refs graph, version-bump guard, tools
+tests) and a change touching only `ca` paths skips every ca-sandbox check. The `ca` governance
+plugin's identity and gates are unchanged; ca-sandbox is infrastructure that arbiter knows about and
+integrates with, not part of the governance kernel.
+
+## Alternatives considered
+- **Separate repository, referenced by the marketplace** — declined. Cleaner identity separation, but
+  a second repo to manage for a solo dev and looser coupling to `farm.ts` (the intended `item-3`
+  integration point).
+- **A tool inside the `ca` plugin** (`plugins/ca/tools/sandbox`) — declined. It would fold
+  infrastructure into the governance plugin, blurring the "orchestration, not infrastructure"
+  boundary and coupling the two release cadences.
+- **Standalone script, not a plugin** — declined. Loses marketplace distribution and the gated
+  skill/command surface the feature warrants.
+
+## Consequences
+Easier: ca-sandbox ships through the existing marketplace, develops alongside arbiter, and has a clean
+seam for the farm `item-3` sandbox. The `ca` plugin stays focused. Harder: the repo's identity is now
+"a marketplace of a governance plugin plus an infrastructure sibling," which `CONTEXT.md` and the
+marketplace description must state explicitly. CI must learn two plugins via path-scoped jobs, and the
+version-bump guard must apply per-plugin. ca-sandbox adds host dependencies (Docker, nixpacks) that
+`ca` never required — these are scoped to the sandbox plugin and must be detected-and-messaged, not
+assumed.
+
+## Risks
+Scope creep: a second plugin invites a third, eroding the framework's focus. Mitigation: ca-sandbox is
+the deliberate, recorded exception, not a precedent for arbitrary co-location. Path-scoped CI is the
+load-bearing assumption — if it is mis-wired, a sandbox change could silently ship `ca` unvalidated (or
+vice versa); the CI work must prove isolation. This decision is proven wrong if the two plugins'
+coupling forces constant cross-plugin changes (showing they were never truly independent), at which
+point either merging them or splitting to separate repos reopens.

.codearbiter/decisions/decision-log.md

@@ -214,3 +214,48 @@ carry the authoritative `status: accepted` frontmatter and a ratification line i
 same decisions, not a new decision.
 
 ---
+
+## DECISION-0007 — ADR-0007 — Host a second sibling plugin (ca-sandbox) in the repo/marketplace
+
+**Date:** 2026-06-20
+**Status:** proposed
+**Supersedes:** none
+**Decided by:** SUaDtL@users.noreply.github.com
+**Decision category:** architecture/governance
+**Artifact-section-hash:** n/a
+
+### Variance summary
+- **Artifact position:** CONTEXT.md frames the repo as "the orchestration framework itself"; marketplace.json says "Single-plugin marketplace."
+- **Scaffold position:** The marketplace `plugins` array supports multiple entries; the ca-sandbox brainstorm needs a home and integrates with farm.ts.
+- **Status type:** open-decision-closure
+
+### Decision
+Host `ca-sandbox` as a second, sibling plugin (`plugins/ca-sandbox/`) in this repo/marketplace,
+distinct from the `ca` governance plugin, with path-scoped CI so neither plugin's changes trigger the
+other's checks. ca-sandbox is infrastructure arbiter integrates with, not part of the governance
+kernel; the `ca` plugin's identity and gates are unchanged.
+
+### SMARTS rationale
+Maintainable + Scalable-at-current-scale favored co-location over a separate repo (one less repo for a
+solo dev; tight `farm.ts` item-3 coupling) while path-scoped CI preserves independence. Securable held
+the line that the governance plugin's gates must not absorb infrastructure concerns — hence sibling,
+not embedded.
+
+### Implementation implication
+Update `.codearbiter/CONTEXT.md` and `.claude-plugin/marketplace.json` descriptions to state the
+two-plugin shape; add the `{ "name": "ca-sandbox", "source": "./plugins/ca-sandbox" }` marketplace
+entry; parameterize/duplicate CI (check-plugin-refs, version-bump, tools tests) per-plugin by path.
+Re-evaluation trigger: if the two plugins require constant cross-plugin changes, reopen to merge or
+split to separate repos.
+
+---
+
+## Ratification — 2026-06-20
+
+DECISION-0007 advanced from `proposed` to **`accepted`** on explicit user instruction
+(SUaDtL@users.noreply.github.com), ratified 2026-06-20. The ADR file
+(`0007-second-plugin-ca-sandbox.md`) carries the authoritative `status: accepted` frontmatter and a
+ratification line in its `## Status` section. No content was superseded — ratification is the
+maturation of this decision, not a new one.
+
+---