diff --git a/.devcontainer/aliases.sh b/.devcontainer/aliases.sh
index a6a360d..b26b14e 100644
--- a/.devcontainer/aliases.sh
+++ b/.devcontainer/aliases.sh
@@ -1,4 +1,5 @@
 alias ll="ls -lah"
 alias gs="git status"
 alias op="opencode"
+alias ocs="opencode-sandbox"
 alias workspaces="cd /workspaces"
diff --git a/AGENTS.md b/AGENTS.md
index 85c5e53..cab2c5c 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -63,7 +63,7 @@ bash scripts/recovery/validate-recovery.sh        # verify workstation is in goo
 | `DB_PATH` | `/workspaces/opencode-workbench/.saga/.tracker.db` |
 | `DEEPSEEK_API_KEY` | primary model: `deepseek/deepseek-v4-pro` |
 | `OPENCODE_API_KEY` | OpenCode Zen + Console Go providers |
-| `SIMONPLMAK_CLOUD_PAT` | GitHub MCP (binary) + shadcn MCP + `gh` auth |
+| `SIMONMAK_ASCENT_PAT` | GitHub MCP (binary) + shadcn MCP + `gh` auth |
 | `NPM_TOKEN` | GitHub Packages (`@simonmak-ascent`) — same PAT |
 | `VERCEL_ACCESS_TOKEN`, `PERPLEXITY_API_KEY`, `BRAVE_API_KEY`, `SENTRY_AUTH_TOKEN`, `MOONSHOT_API_KEY`, `SURREAL_*`, `ALIBABA_CLOUD_*`, `AZURE_*`, `STRIPE_SECRET_KEY` | respective MCP servers/providers |
 
@@ -83,6 +83,7 @@ bash .devcontainer/start-browserless.sh
 - **Toolchain**: `node` 22, `corepack`/`pnpm`, `uv` + Python 3.11, `rsync`, `gcc-c++`
 - **CLI**: `gh`, `vercel`, `opencode` (aliased as `op`), `opencode serve`
 - **Playwright**: chromium (headless shell) + RHEL system libs
+- **Sandbox**: `opencode-sandbox` (bubblewrap) — run OpenCode with a read-only system, a writable workspace, and no access to `~/.ssh` or `~/.env.workbench`; installed by the optional `sandbox` component (`scripts/sandbox/opencode-sandbox.sh`)
 
 ## OpenCode
 
diff --git a/README.md b/README.md
index f1a2ba2..5f9cf88 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,7 @@ This repository is the **single source of truth** for a complete cloud developme
 - Operational prompts (disaster recovery, backup, security)
 - Recovery procedures (playbook, checklist, gap analysis)
 - Security governance (secret management, threat model)
+- OpenCode sandbox (bubblewrap) — run the agent with a read-only system and no secret mounts
 - **`opencode-workbench`** — an MCP server that installs this profile on any Linux box
 
 **No important knowledge exists only in human memory.**
@@ -181,7 +182,7 @@ All secrets stored in the build box Secrets. Never in repository files.
 |---|--------|---------|
 | 1 | `DEEPSEEK_API_KEY` | OpenCode (primary model) |
 | 2 | `OPENCODE_API_KEY` | OpenCode Zen / Console Go providers |
-| 3 | `SIMONPLMAK_CLOUD_PAT` | GitHub MCP, shadcn MCP, `gh` |
+| 3 | `SIMONMAK_ASCENT_PAT` | GitHub MCP, shadcn MCP, `gh` |
 | 4 | `PERPLEXITY_API_KEY` | Perplexity MCP |
 | 5 | `BRAVE_API_KEY` | Brave Search MCP |
 | 6 | `BROWSERLESS_TOKEN` | Browserless MCP + container |
diff --git a/connector.json b/connector.json
index 4602665..878d25d 100644
--- a/connector.json
+++ b/connector.json
@@ -3,7 +3,7 @@
   "name": "opencode-workbench",
   "title": "OpenCode Workbench",
   "description": "Clones the OpenCode workbench installation onto Linux machines, locally or over SSH.",
-  "version": "3.0.0",
+  "version": "3.1.0",
   "transport": {
     "type": "stdio",
     "command": "npx",
diff --git a/docs/CHANGELOG_WORKBENCH.md b/docs/CHANGELOG_WORKBENCH.md
index 0e33369..9c10067 100644
--- a/docs/CHANGELOG_WORKBENCH.md
+++ b/docs/CHANGELOG_WORKBENCH.md
@@ -3,6 +3,16 @@
 > All notable changes to the workbench configuration.
 > Format: [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
+## [2026-10-03] — v3.1.0
+
+### Added
+- **`sandbox` component** — optional [bubblewrap](https://github.com/containers/bubblewrap)
+  sandbox for the OpenCode CLI. Installs `~/.local/bin/opencode-sandbox` (alias `ocs`),
+  which runs `opencode` with a read-only system, writable workspace + OpenCode state only,
+  and no access to `~/.ssh`, cloud credentials or `~/.env.workbench`. Wrapper:
+  `scripts/sandbox/opencode-sandbox.sh`.
+- Documented the sandbox under `docs/security-model.md` (Layer 2b) and `mcp-server/README.md`.
+
 ## [2026-10-03] — v3.0.0
 
 ### Breaking
@@ -153,7 +163,7 @@
 
 ### Changed
 - **Active model**: `kimi-for-coding/k3` → `deepseek/deepseek-v4-pro`
-- **devcontainer.json `remoteEnv`**: Added 6 missing env vars (BROWSERLESS_TOKEN, PERPLEXITY_API_KEY, BRAVE_API_KEY, FIGMA_TOKEN, SENTRY_AUTH_TOKEN, SIMONPLMAK_CLOUD_PAT, DEEPSEEK_API_KEY, DB_PATH)
+- **devcontainer.json `remoteEnv`**: Added 6 missing env vars (BROWSERLESS_TOKEN, PERPLEXITY_API_KEY, BRAVE_API_KEY, FIGMA_TOKEN, SENTRY_AUTH_TOKEN, SIMONMAK_ASCENT_PAT, DEEPSEEK_API_KEY, DB_PATH)
 - **Figma MCP**: Fixed env var name from `FIGMA_TOKEN` → `FIGMA_API_KEY`
 - Runtime sync: `~/.config/opencode/opencode.json` synced from repo
 - Updated `docs/environment-inventory.md` — reflected model change, added new vars
diff --git a/docs/security-model.md b/docs/security-model.md
index 6cbfebb..83534ad 100644
--- a/docs/security-model.md
+++ b/docs/security-model.md
@@ -40,7 +40,7 @@
 | Tier | Description | Examples | Storage |
 |------|-------------|----------|---------|
 | **Tier 0 — Platform** | GitHub-injected tokens | `GITHUB_TOKEN`, `GH_TOKEN` | Automatic |
-| **Tier 1 — Critical** | Required for core function | `DEEPSEEK_API_KEY`, `SIMONPLMAK_CLOUD_PAT` | build box Secrets |
+| **Tier 1 — Critical** | Required for core function | `DEEPSEEK_API_KEY`, `SIMONMAK_ASCENT_PAT` | build box Secrets |
 | **Tier 2 — Operational** | Required for MCP servers | `BRAVE_API_KEY`, `SENTRY_AUTH_TOKEN`, `FIGMA_TOKEN`, `PERPLEXITY_API_KEY`, `BROWSERLESS_TOKEN` | build box Secrets |
 | **Tier 3 — Optional** | Nice to have, not critical | `OPENROUTER_API_KEY`, `GOOGLE_API_KEY`, `KIMI_API_KEY` | build box Secrets |
 | **Tier 4 — Non-Secret** | Configuration only | `DATABASE_URL`, `DB_PATH`, `BROWSERLESS_HOST` | `devcontainer.json` |
@@ -57,6 +57,23 @@
 - Each MCP server receives only its required environment variables
 - `opencode.json` uses named `{env:VAR}` references (not blanket env passthrough)
 
+### Layer 2b: OpenCode Sandboxing
+The optional `sandbox` component installs **bubblewrap** and `~/.local/bin/opencode-sandbox`,
+a wrapper that runs the OpenCode CLI (`opencode-sandbox [args...]`, alias `ocs`) inside a
+bubblewrap namespace:
+
+- **Read-only system** — `/usr`, `/etc`, `/bin`, `/lib`, `/opt`, `/run` are mounted `--ro-bind`.
+- **Writable, scoped state** — only the workspace and OpenCode's own directories
+  (`~/.config/opencode`, `~/.local/share/opencode`, `~/.cache/opencode`,
+  `~/.local/state/opencode`) are writable.
+- **Secrets excluded** — `~/.ssh`, `~/.env.workbench`, `~/.aws`, `~/.config/gh` and
+  other home paths are **not** mounted, so the agent cannot read them.
+- **Network allowed by default** (remote model APIs); set `OPENCODE_SANDBOX_NO_NET=1`
+  for `--unshare-net` isolation.
+
+Requires kernel support for unprivileged user namespaces; where unavailable the installer
+warns and the component fails closed (run `opencode` directly only if you accept that).
+
 ### Layer 3: Documentation Discipline
 - Secrets documented by name and purpose only
 - Never record values, prefixes, or lengths in docs
diff --git a/mcp-server/README.md b/mcp-server/README.md
index 7a986ac..6e06e1c 100644
--- a/mcp-server/README.md
+++ b/mcp-server/README.md
@@ -58,7 +58,7 @@ Every tool takes a `target`:
 
 - **required** — `git`, `curl`, `node` (>=20), `opencode`
 - **core** — `pnpm`, `uv`, `gh`, `npm-mcps`, `vendored-mcps`, `research-mcps`, `skills`, `plugins`, `playwright-browsers`
-- **optional** — `github-mcp`, `docker`, `docker-containers`, `data-tools`, `scientific`, `db-clients`
+- **optional** — `github-mcp`, `docker`, `docker-containers`, `data-tools`, `scientific`, `db-clients`, `sandbox`
 
 Add-ons (esg-hub, humanity4ai, saga, surrealdb, google-workspace, google-search,
 ms-365, stripe, alibaba-cloud-ops, designlang, difflens) are omitted from the rendered
@@ -70,6 +70,11 @@ The connector **never reads, transmits, or writes secret values**. It writes an
 `~/.env.workbench` template (mode `600`) listing the `{env:VAR}` names the rendered
 config references. Fill them on the target.
 
+The optional `sandbox` component installs [bubblewrap](https://github.com/containers/bubblewrap)
+and an `opencode-sandbox` wrapper that runs the OpenCode CLI with a read-only system and
+only the workspace + OpenCode's own state directories mounted — `~/.ssh`, cloud
+credentials and `~/.env.workbench` stay outside the sandbox.
+
 ## Development
 
 ```bash
diff --git a/mcp-server/src/components.ts b/mcp-server/src/components.ts
index 3256eae..68f4024 100644
--- a/mcp-server/src/components.ts
+++ b/mcp-server/src/components.ts
@@ -330,6 +330,25 @@ pip3 install --break-system-packages -q numpy scipy pandas matplotlib sympy || w
     install: `pkg_install postgresql-client || true
 pipx install pgcli 2>/dev/null || true`,
   },
+  {
+    id: "sandbox",
+    title: "OpenCode sandbox (bubblewrap)",
+    tier: "optional",
+    description:
+      "Runs the OpenCode CLI in a bubblewrap sandbox: read-only system, writable workspace, and no access to ~/.ssh, cloud credentials or ~/.env.workbench.",
+    preview: "install bubblewrap and ~/.local/bin/opencode-sandbox",
+    detect: `command -v bwrap >/dev/null 2>&1 && [ -x "$WB_HOME/.local/bin/opencode-sandbox" ]`,
+    install: `
+command -v bwrap >/dev/null 2>&1 || pkg_install bubblewrap || true
+command -v bwrap >/dev/null 2>&1 || { warn "bubblewrap unavailable (kernel may block unprivileged user namespaces)"; exit 1; }
+if [ -z "\${WB_REPO:-}" ] || [ ! -f "$WB_REPO/scripts/sandbox/opencode-sandbox.sh" ]; then
+  warn "sandbox script not found under WB_REPO"; exit 1
+fi
+mkdir -p "$WB_HOME/.local/bin"
+install -m 0755 "$WB_REPO/scripts/sandbox/opencode-sandbox.sh" "$WB_HOME/.local/bin/opencode-sandbox"
+ok "opencode-sandbox -> ~/.local/bin/opencode-sandbox"
+`,
+  },
 ];
 
 export function componentById(id: string): Component | undefined {
@@ -361,6 +380,7 @@ ${CORE_NPM_MCPS.map((p) => `  npm rm -g --silent ${p} >/dev/null 2>&1 || true`).
   "docker-containers": `command -v docker >/dev/null 2>&1 || { warn "docker missing"; exit 1; }
 docker rm -f pg-memory browserless >/dev/null 2>&1 || true`,
   "playwright-browsers": `rm -rf "$WB_HOME/.cache/ms-playwright"`,
+  sandbox: `rm -f "$WB_HOME/.local/bin/opencode-sandbox"`,
 };
 
 /** Uninstall script for a component id, or undefined when removal is manual. */
diff --git a/mcp-server/test/component-actions.test.ts b/mcp-server/test/component-actions.test.ts
index 797d7c9..d23a041 100644
--- a/mcp-server/test/component-actions.test.ts
+++ b/mcp-server/test/component-actions.test.ts
@@ -23,6 +23,7 @@ describe("component uninstall coverage", () => {
       "plugins",
       "docker-containers",
       "playwright-browsers",
+      "sandbox",
     ]) {
       expect(typeof uninstallScript(id), `missing uninstall for ${id}`).toBe("string");
     }
diff --git a/mcp-server/test/server.test.ts b/mcp-server/test/server.test.ts
index 7471b2b..0dc7c31 100644
--- a/mcp-server/test/server.test.ts
+++ b/mcp-server/test/server.test.ts
@@ -57,6 +57,7 @@ describe("opencode-workbench server", () => {
       optionalMcp: string[];
     };
     expect(info.components.some((c) => c.id === "opencode" && c.tier === "required")).toBe(true);
+    expect(info.components.some((c) => c.id === "sandbox" && c.tier === "optional")).toBe(true);
     expect(info.optionalMcp).toContain("saga");
     await client.close();
   });
diff --git a/package.json b/package.json
index 3590d86..729321e 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "@simonmak-ascent/opencode-workbench",
   "mcpName": "io.github.simonmak-ascent/opencode-workbench",
-  "version": "3.0.0",
+  "version": "3.1.0",
   "description": "MCP server and connector that clones the OpenCode workbench configuration onto Linux machines (locally or over SSH).",
   "license": "MIT",
   "type": "module",
diff --git a/scripts/sandbox/opencode-sandbox.sh b/scripts/sandbox/opencode-sandbox.sh
new file mode 100755
index 0000000..166fa55
--- /dev/null
+++ b/scripts/sandbox/opencode-sandbox.sh
@@ -0,0 +1,99 @@
+#!/usr/bin/env bash
+#
+# opencode-sandbox — run the OpenCode CLI inside a bubblewrap (bwrap) sandbox.
+#
+# Security goal: the agent process gets a read-only system, a writable copy of
+# its workspace and OpenCode's own state directories, and NOTHING ELSE from your
+# home. Your SSH keys (~/.ssh), cloud credentials (~/.aws, ~/.config/gcloud),
+# GitHub tokens (~/.config/gh) and the secrets file ~/.env.workbench are not
+# mounted, so a compromised or misbehaving agent cannot read them.
+#
+# Usage:
+#   opencode-sandbox [args...]            # same args as `opencode`
+#   opencode-sandbox run "..."            # e.g. `opencode run` in the sandbox
+#
+# Environment:
+#   OPENCODE_SANDBOX_CWD=<dir>   working dir to expose read-write (default: $PWD)
+#   OPENCODE_SANDBOX_NO_NET=1    isolate the network (default: network allowed,
+#                                because model APIs are remote)
+#   OPENCODE_SANDBOX_RW=<paths>  extra colon-separated paths to bind read-write
+#   OPENCODE_SANDBOX_RO=<paths>  extra colon-separated paths to bind read-only
+#   OPENCODE_SANDBOX_BIN=<path>  opencode binary (default: resolved via PATH)
+#
+# Requires: bubblewrap (`bwrap`). Install with e.g.
+#   sudo apt-get install -y bubblewrap   # Debian/Ubuntu
+#   sudo dnf install -y bubblewrap        # Fedora/RHEL
+#
+set -euo pipefail
+
+if ! command -v bwrap >/dev/null 2>&1; then
+  echo "opencode-sandbox: bubblewrap (bwrap) is required." >&2
+  echo "  Debian/Ubuntu: sudo apt-get install -y bubblewrap" >&2
+  echo "  Fedora/RHEL:   sudo dnf install -y bubblewrap" >&2
+  echo "  Alpine:        sudo apk add bubblewrap" >&2
+  echo "Refusing to run unsandboxed. Use 'opencode' directly if you accept that." >&2
+  exit 127
+fi
+
+WORKDIR="${OPENCODE_SANDBOX_CWD:-$PWD}"
+HOME_DIR="${HOME:-/root}"
+OPENCODE_BIN="${OPENCODE_SANDBOX_BIN:-$(command -v opencode || true)}"
+
+if [ -z "$OPENCODE_BIN" ]; then
+  echo "opencode-sandbox: 'opencode' not found on PATH (set OPENCODE_SANDBOX_BIN)." >&2
+  exit 127
+fi
+
+args=(
+  --die-with-parent
+  --new-session
+  --unshare-pid
+  --unshare-uts
+  --unshare-ipc
+  --proc /proc
+  --dev /dev
+  --tmpfs /tmp
+)
+
+# Read-only system.
+for d in /usr /etc /bin /sbin /lib /lib64 /opt /run; do
+  [ -e "$d" ] && args+=(--ro-bind "$d" "$d")
+done
+
+# Writable workspace.
+[ -d "$WORKDIR" ] && args+=(--bind "$WORKDIR" "$WORKDIR")
+
+# OpenCode's own state — writable, created if absent. These are the only parts
+# of $HOME the sandbox sees.
+for d in \
+  "$HOME_DIR/.config/opencode" \
+  "$HOME_DIR/.local/share/opencode" \
+  "$HOME_DIR/.cache/opencode" \
+  "$HOME_DIR/.local/state/opencode"; do
+  mkdir -p "$d" 2>/dev/null || true
+  [ -e "$d" ] && args+=(--bind "$d" "$d")
+done
+
+# Where the opencode binary itself may live (read-only).
+for d in "$HOME_DIR/.opencode" "$HOME_DIR/.local/bin" "$HOME_DIR/.npm-global"; do
+  [ -e "$d" ] && args+=(--ro-bind "$d" "$d")
+done
+
+# Caller-provided extra mounts (colon-separated path lists).
+if [ -n "${OPENCODE_SANDBOX_RO:-}" ]; then
+  IFS=':' read -r -a _ro <<<"$OPENCODE_SANDBOX_RO"
+  for p in "${_ro[@]}"; do [ -e "$p" ] && args+=(--ro-bind "$p" "$p"); done
+fi
+if [ -n "${OPENCODE_SANDBOX_RW:-}" ]; then
+  IFS=':' read -r -a _rw <<<"$OPENCODE_SANDBOX_RW"
+  for p in "${_rw[@]}"; do [ -e "$p" ] && args+=(--bind "$p" "$p"); done
+fi
+
+# Network is allowed by default (remote model APIs); opt into isolation.
+if [ "${OPENCODE_SANDBOX_NO_NET:-0}" = "1" ]; then
+  args+=(--unshare-net)
+fi
+
+args+=(--setenv HOME "$HOME_DIR" --chdir "$WORKDIR")
+
+exec bwrap "${args[@]}" -- "$OPENCODE_BIN" "$@"
diff --git a/server.json b/server.json
index 2905ac7..d610f11 100644
--- a/server.json
+++ b/server.json
@@ -2,7 +2,7 @@
   "$schema": "https://static.modelcontextprotocol.io/schemas/2025-07-09/server.schema.json",
   "name": "io.github.simonmak-ascent/opencode-workbench",
   "description": "Provision an OpenCode workbench and MCP stack on any Linux box, local or over SSH.",
-  "version": "3.0.0",
+      "version": "3.1.0",
   "repository": {
     "url": "https://github.com/simonmak-ascent/opencode-workbench",
     "source": "github"
@@ -11,7 +11,7 @@
     {
       "registryType": "npm",
       "identifier": "@simonmak-ascent/opencode-workbench",
-      "version": "3.0.0",
+  "version": "3.1.0",
       "transport": { "type": "stdio" }
     }
   ],
diff --git a/vdd/specs/opencode-sandbox/spec.md b/vdd/specs/opencode-sandbox/spec.md
new file mode 100644
index 0000000..2850ace
--- /dev/null
+++ b/vdd/specs/opencode-sandbox/spec.md
@@ -0,0 +1,41 @@
+# Spec — opencode-sandbox
+
+> Traces to: `vdd/vision.md` (security of the provisioned host), `vdd/tactics.md` A-012.
+> Status: implemented (v3.1.0).
+
+## User story
+
+As an operator who lets an AI agent run shell commands on a workstation, I want the
+OpenCode CLI to run inside an OS-level sandbox with a read-only system and no access to
+my SSH keys, cloud credentials or secrets file, so that a compromised or misbehaving
+agent cannot read or exfiltrate them.
+
+## Boundaries
+
+- **Always**
+  - Refuse to run unsandboxed (fail closed) when `bwrap` is unavailable.
+  - Mount the system read-only and expose only the workspace + OpenCode's own state dirs.
+  - Keep `~/.ssh`, `~/.env.workbench`, `~/.aws`, `~/.config/gh` out of the sandbox.
+- **Ask**
+  - Nothing at runtime; installation is opt-in via the `sandbox` component.
+- **Never**
+  - Never run the agent as root inside the sandbox.
+  - Never mount the whole home directory.
+
+## Acceptance criteria
+
+- **AC-1** Given `bwrap` is installed, when I run `opencode-sandbox run "..."`, then the
+  command executes inside a bubblewrap namespace with `/usr` read-only.
+- **AC-2** Given `~/.ssh` exists, when the sandbox runs, then `~/.ssh` is absent inside it.
+- **AC-3** Given `bwrap` is missing, when I run `opencode-sandbox`, then it exits non-zero
+  with install guidance and does not run `opencode`.
+- **AC-4** Given `OPENCODE_SANDBOX_NO_NET=1`, when the sandbox runs, then the network is
+  unshared.
+- **AC-5** Given the `sandbox` component is installed, when `remove_component sandbox` runs,
+  then `~/.local/bin/opencode-sandbox` is removed.
+
+## Non-functional
+
+- Portable across apt/dnf/apk/pacman/zypper hosts (via the shared `pkg_install` preamble).
+- No root at run time (user namespaces); `sudo` only at install time.
+- The wrapper is shell-only and has no network calls of its own.
diff --git a/vdd/tactics.md b/vdd/tactics.md
index 3b982ca..0e06bb8 100644
--- a/vdd/tactics.md
+++ b/vdd/tactics.md
@@ -76,6 +76,7 @@ Derived from: `vdd/strategy.md`. Scope: Infrastructure only.
 | A-009 | Add `server.json` manifest for the Official MCP Registry | MUST | Distribution | S | None |
 | A-010 | Registry-listing runbook + claim/verify each of the 5 registries; automate what the API allows | MUST | Distribution | M | A-009 |
 | A-011 | Capture a full `mcp-tdqs score` (tier A floor) and wire a CI gate when a scorer key is available | SHOULD | P1 | M | A-008 |
+| A-012 | Add an optional `sandbox` component: a bubblewrap wrapper (`scripts/sandbox/opencode-sandbox.sh`) confining the OpenCode CLI (read-only system, no `~/.ssh`/secret mounts) | SHOULD | Security | S | None |
 
 **AMEND dependency map:** `A-002 → A-008 → A-011`; `A-009 → A-010`.
 **AMEND blocker:** A-011 (full score) and Smithery/PulseMCP listing require credentials the