Add --exec option

README.md

@@ -50,6 +50,7 @@ opencodebox [OPTIONS] [OPENCODE_ARGS...]
 
 - `--with /host[:/sandbox]` - Bind host path read-write to sandbox
 - `--with-ro /host[:/sandbox]` - Bind host path read-only to sandbox
+- `--exec COMMAND` - Run `COMMAND` inside the sandbox instead of `opencode`
 
 These options allow you to specify additional directories to mount inside the sandbox for read-write or read-only access.
 
@@ -70,11 +71,17 @@ opencodebox --with-ro /etc/hosts
 
 # Run sandboxed opencode server with specified bind mounts
 opencodebox --with /data --with-ro /config serve
+
+# Run a custom command inside the sandbox
+opencodebox --exec /bin/bash
+
+# Run a custom command with arguments
+opencodebox --exec /bin/bash -l
 ```
 
 ## How It Works
 
-1. Parse arguments (`--with`, `--with-ro`, `--version`, `--help`)
+1. Parse arguments (`--with`, `--with-ro`, `--exec`, `--version`, `--help`)
 2. Check prerequisites (bwrap and opencode)
 3. Load seccomp sandbox filter (see [details](#seccomp-sandbox-filter))
 4. **Enforce security restrictions**:
@@ -84,7 +91,7 @@ opencodebox --with /data --with-ro /config serve
 5. Build bubblewrap sandbox with namespace isolation and bind mounts
 6. Setup SSH (sanitized `.pub` keys, `known_hosts`, agent forwarding)
 7. Add conditional tool mounts (bun, npm, pnpm, uv, pipenv, cargo, git, mise) and extra bind mounts
-8. Execute opencode inside the sandbox
+8. Execute the target command (`opencode` by default, or `--exec` override) inside the sandbox
 
 ## Bind Mounts Structure
 

opencodebox

@@ -7,6 +7,9 @@
 # ============================================================
 
 VERSION="0.4.4"
+# Command to run inside the sandbox; empty means the opencode launcher
+# detected later (OPCODE_SANDBOX_PATH) is used.
+EXEC_CMD=""
 
 print_version() {
     local opencode_version
@@ -27,6 +30,7 @@ Usage:
 Options:
   --with /host[:/sandbox]      Bind host path read-write (sandbox path defaults to host path)
   --with-ro /host[:/sandbox]   Bind host path read-only (sandbox path defaults to host path)
+  --exec COMMAND               Run COMMAND inside the sandbox instead of opencode
   --version, -v                Show version information
   --help, -h                   Show this help message
 
@@ -43,6 +47,7 @@ Examples:
   opencodebox --with /mnt/data:/workspace/data
   opencodebox --with-ro /etc/hosts
   opencodebox --with ~/another-project1 --with-ro ~/another-project2 serve
+  opencodebox --exec /bin/bash
 EOF
     exit 0
 }
@@ -253,6 +258,17 @@ while [[ $# -gt 0 ]]; do
             parse_bind_arg "--ro-bind" "$1"
             shift
             ;;
+        # --exec: override the command to run inside the sandbox
+        --exec)
+            shift
+            if [[ $# -eq 0 ]]; then
+                echo "Error: --exec requires a value" >&2
+                echo "Usage: opencodebox --exec /path/to/command [ARGS...]" >&2
+                exit 1
+            fi
+            EXEC_CMD="$1"
+            shift
+            ;;
         # Pass through all other args to opencode
         *)
             REMAINING_ARGS+=("$1")
@@ -411,6 +427,9 @@ if [[ "${OPCODE_DIR##*/}" == ".bin" ]]; then
 fi
 OPCODE_SANDBOX_PATH="/opt/opencode/$OPCODE_LAUNCHER"
 
+# --exec overrides the command run inside the sandbox; default is opencode.
+[[ -z "$EXEC_CMD" ]] && EXEC_CMD="$OPCODE_SANDBOX_PATH"
+
 # bwrap --bind hard-fails if the source is missing; opencode v2 keeps state under
 # ~/.local/state/opencode, which v1 users and fresh hosts may not have created yet.
 STATE_DIR="$HOME/.local/state/opencode"
@@ -690,5 +709,5 @@ exec bwrap "${BWRAP_ARGS[@]}" -- \
         if [ "'"$mise_installed"'" = true ]; then
             eval "$(mise activate bash)"
         fi
-        exec "'"$OPCODE_SANDBOX_PATH"'" "$@"
+        exec "'"$EXEC_CMD"'" "$@"
     ' -- "$@"

tests/test_launcher.py

@@ -123,6 +123,37 @@ def test_passthrough_args_reach_opencode(launcher):
     assert command[3:] == ["--", "-s", "session", "run", "prompt"]
 
 
+def test_exec_overrides_default_command(launcher):
+    _, command = launcher.captured(launcher.run_launcher("--exec", "/bin/bash"))
+    assert command[3:] == ["--"]
+    assert 'exec "/bin/bash"' in command[2]
+
+
+def test_exec_with_passthrough_args(launcher):
+    _, command = launcher.captured(launcher.run_launcher("--exec", "/bin/bash", "-l"))
+    assert command[3:] == ["--", "-l"]
+    assert 'exec "/bin/bash"' in command[2]
+
+
+def test_exec_requires_value(launcher):
+    launcher.assert_rejected("--exec")
+
+
+def test_default_command_is_opencode(launcher):
+    _, command = launcher.captured(launcher.run_launcher())
+    assert command[3:] == ["--"]
+    assert 'exec "/opt/opencode/opencode"' in command[2]
+
+
+def test_exec_with_binds(launcher):
+    extra = launcher.root / "extra"
+    extra.mkdir()
+    options, command = launcher.captured(launcher.run_launcher("--with", str(extra), "--exec", "/bin/sh"))
+    assert has_seq(options, ["--bind", str(extra), str(extra)])
+    assert command[3:] == ["--"]
+    assert 'exec "/bin/sh"' in command[2]
+
+
 def test_reject_sensitive_and_bad_binds(launcher):
     launcher.assert_rejected("--with", str(launcher.home))
     launcher.assert_rejected("--with", "/")