diff --git a/profiles/opencode.toml b/profiles/opencode.toml
new file mode 100644
index 0000000..f088b9e
--- /dev/null
+++ b/profiles/opencode.toml
@@ -0,0 +1,31 @@
+# OpenCode profile
+# Provides access to OpenCode configuration and cache directories
+network_mode = "online"
+
+[filesystem]
+allow_read = [
+    # Custom open code
+    "~/.local/share/opencode",
+    "~/.local/state/opencode",
+    "~/.config/opencode",
+    "~/.cache/opencode",
+    "/private/tmp/.*",
+]
+
+allow_write = [
+    # Open code
+    "~/.config/opencode",
+    "~/.local/share/opencode",
+    "~/.local/state/opencode",
+    "~/.cache/opencode",
+    "/private/tmp/.*",
+]
+
+# Directory listing permissions
+allow_list_dirs = [
+    "/private/tmp"
+]
+
+[shell]
+# No additional environment variables needed
+pass_env = []
\ No newline at end of file
diff --git a/src/cli/args.rs b/src/cli/args.rs
index db93b68..36a9a23 100644
--- a/src/cli/args.rs
+++ b/src/cli/args.rs
@@ -17,7 +17,8 @@ pub use crate::config::schema::NetworkMode;
     localhost   Localhost network only\n    \
     rust        Rust/Cargo toolchain\n    \
     claude      Claude Code (~/.claude access)\n    \
-    gpg         GPG signing support")]
+    gpg         GPG signing support\n    \
+    opencode    OpenCode (~/.config/opencode access)")]
 pub struct Args {
     /// Enable verbose output (show sandbox config)
     #[arg(short, long)]
diff --git a/src/cli/commands.rs b/src/cli/commands.rs
index da58e3c..739c4b0 100644
--- a/src/cli/commands.rs
+++ b/src/cli/commands.rs
@@ -195,14 +195,24 @@ fn load_effective_config(args: &Args, working_dir: &Path) -> Result<Config> {
         return Ok(Config::default());
     }
 
-    // Load global config
-    let global =
-        load_global_config(args.config.as_deref()).context("Failed to load global config")?;
+    // Explicit -c flag: treat as project config
+    if let Some(config_path) = &args.config {
+        let content = std::fs::read_to_string(config_path)
+            .with_context(|| format!("Failed to read config: {}", config_path.display()))?;
+        let project: Config = toml::from_str(&content)
+            .with_context(|| format!("Failed to parse config: {}", config_path.display()))?;
+
+        if project.sandbox.inherit_global {
+            let global = load_global_config(None).context("Failed to load global config")?;
+            return Ok(merge_configs(&global, &project));
+        }
+        return Ok(project);
+    }
 
-    // Load project config
+    // Default: load global config and project config from working directory
+    let global = load_global_config(None).context("Failed to load global config")?;
     let project = load_project_config(working_dir).context("Failed to load project config")?;
 
-    // Merge if project config exists and inherits
     match project {
         Some(proj) if proj.sandbox.inherit_global => Ok(merge_configs(&global, &proj)),
         Some(proj) => Ok(proj),
@@ -382,7 +392,7 @@ fn generate_config_template() -> &'static str {
 inherit_global = true
 
 # Profiles to apply for this project
-# Available: base, online, localhost, rust, claude, gpg
+# Available: base, online, localhost, rust, claude, gpg, opencode
 profiles = []
 
 # Default network mode: "offline", "online", or "localhost"
diff --git a/src/config/profile.rs b/src/config/profile.rs
index 8dd4550..f6ffb07 100644
--- a/src/config/profile.rs
+++ b/src/config/profile.rs
@@ -102,6 +102,7 @@ pub enum BuiltinProfile {
     Claude,
     Gpg,
     Bun,
+    Opencode,
 }
 
 impl BuiltinProfile {
@@ -115,6 +116,7 @@ impl BuiltinProfile {
             "claude" => Some(Self::Claude),
             "gpg" => Some(Self::Gpg),
             "bun" => Some(Self::Bun),
+            "opencode" => Some(Self::Opencode),
             _ => None,
         }
     }
@@ -129,6 +131,7 @@ impl BuiltinProfile {
             Self::Claude => "claude",
             Self::Gpg => "gpg",
             Self::Bun => "bun",
+            Self::Opencode => "opencode",
         }
     }
 
@@ -146,6 +149,7 @@ impl BuiltinProfile {
             Self::Claude => include_str!("../../profiles/claude.toml"),
             Self::Gpg => include_str!("../../profiles/gpg.toml"),
             Self::Bun => include_str!("../../profiles/bun.toml"),
+            Self::Opencode => include_str!("../../profiles/opencode.toml"),
         };
         toml::from_str(toml_str).map_err(|e| ProfileError::InvalidBuiltin {
             name: self.name(),
diff --git a/tests/config_test.rs b/tests/config_test.rs
index 2052b90..205c575 100644
--- a/tests/config_test.rs
+++ b/tests/config_test.rs
@@ -280,3 +280,182 @@ fn test_merge_configs_shell_env() {
         Some(&"active".to_string())
     );
 }
+
+#[test]
+fn test_inherit_global_true_merges_configs() {
+    let temp_dir = TempDir::new().unwrap();
+
+    // Write a global config
+    let global_path = temp_dir.path().join("global.toml");
+    std::fs::write(
+        &global_path,
+        r#"
+[filesystem]
+allow_read = ["~/.gitconfig"]
+"#,
+    )
+    .unwrap();
+
+    // Write a project config with inherit_global = true (default)
+    let project_path = temp_dir.path().join(".sandbox.toml");
+    std::fs::write(
+        &project_path,
+        r#"
+[sandbox]
+inherit_global = true
+
+[filesystem]
+allow_read = ["~/.claude"]
+"#,
+    )
+    .unwrap();
+
+    let global = load_global_config(Some(&global_path)).unwrap();
+    let project = load_project_config(temp_dir.path()).unwrap().unwrap();
+
+    // Simulate load_effective_config: inherit_global=true → merge
+    assert!(project.sandbox.inherit_global);
+    let effective = merge_configs(&global, &project);
+
+    // Both global and project paths should be present
+    assert!(effective.filesystem.allow_read.contains(&"~/.gitconfig".to_string()));
+    assert!(effective.filesystem.allow_read.contains(&"~/.claude".to_string()));
+}
+
+#[test]
+fn test_inherit_global_false_skips_global() {
+    let temp_dir = TempDir::new().unwrap();
+
+    // Write a global config with extra paths
+    let global_path = temp_dir.path().join("global.toml");
+    std::fs::write(
+        &global_path,
+        r#"
+[sandbox]
+default_network = "online"
+
+[filesystem]
+allow_read = ["~/.gitconfig", "~/.cargo"]
+"#,
+    )
+    .unwrap();
+
+    // Write a project config that opts out of global inheritance
+    let project_path = temp_dir.path().join(".sandbox.toml");
+    std::fs::write(
+        &project_path,
+        r#"
+[sandbox]
+inherit_global = false
+
+[filesystem]
+allow_read = ["~/.claude"]
+"#,
+    )
+    .unwrap();
+
+    let global = load_global_config(Some(&global_path)).unwrap();
+    let project = load_project_config(temp_dir.path()).unwrap().unwrap();
+
+    // Simulate load_effective_config: inherit_global=false → use project only
+    assert!(!project.sandbox.inherit_global);
+    let effective = if project.sandbox.inherit_global {
+        merge_configs(&global, &project)
+    } else {
+        project
+    };
+
+    // Only project paths, global paths must NOT be present
+    assert!(effective.filesystem.allow_read.contains(&"~/.claude".to_string()));
+    assert!(!effective.filesystem.allow_read.contains(&"~/.gitconfig".to_string()));
+    assert!(!effective.filesystem.allow_read.contains(&"~/.cargo".to_string()));
+    // Network stays at project default (offline), not inherited from global (online)
+    assert_eq!(effective.sandbox.default_network, NetworkMode::Offline);
+}
+
+#[test]
+fn test_custom_config_inherit_global_false_uses_standalone() {
+    // When -c specifies a config with inherit_global = false,
+    // it is used as-is without merging with the global config.
+    let temp_dir = TempDir::new().unwrap();
+
+    let global_path = temp_dir.path().join("global.toml");
+    std::fs::write(
+        &global_path,
+        r#"
+[filesystem]
+allow_read = ["~/.gitconfig"]
+"#,
+    )
+    .unwrap();
+
+    let custom_path = temp_dir.path().join("custom.toml");
+    std::fs::write(
+        &custom_path,
+        r#"
+[sandbox]
+inherit_global = false
+
+[filesystem]
+allow_read = ["~/.custom"]
+"#,
+    )
+    .unwrap();
+
+    // Simulate load_effective_config with -c flag
+    let content = std::fs::read_to_string(&custom_path).unwrap();
+    let project: Config = toml::from_str(&content).unwrap();
+
+    // inherit_global = false → use project config as-is
+    assert!(!project.sandbox.inherit_global);
+    assert!(project.filesystem.allow_read.contains(&"~/.custom".to_string()));
+    assert!(!project.filesystem.allow_read.contains(&"~/.gitconfig".to_string()));
+}
+
+#[test]
+fn test_custom_config_inherit_global_true_merges_with_global() {
+    // When -c specifies a config with inherit_global = true,
+    // it is merged with the global config from the default location.
+    let temp_dir = TempDir::new().unwrap();
+
+    let global_path = temp_dir.path().join("global.toml");
+    std::fs::write(
+        &global_path,
+        r#"
+[filesystem]
+allow_read = ["~/.gitconfig", "~/.config/git/"]
+allow_write = ["~/.cache/"]
+"#,
+    )
+    .unwrap();
+
+    let custom_path = temp_dir.path().join("custom.toml");
+    std::fs::write(
+        &custom_path,
+        r#"
+[sandbox]
+inherit_global = true
+profiles = ["online"]
+
+[filesystem]
+allow_read = ["~/.custom"]
+allow_write = ["~/.custom-data/"]
+"#,
+    )
+    .unwrap();
+
+    // Simulate load_effective_config with -c flag + inherit_global = true
+    let content = std::fs::read_to_string(&custom_path).unwrap();
+    let project: Config = toml::from_str(&content).unwrap();
+    let global = load_global_config(Some(&global_path)).unwrap();
+
+    assert!(project.sandbox.inherit_global);
+    let effective = merge_configs(&global, &project);
+
+    // Both global and project paths should be merged
+    assert!(effective.filesystem.allow_read.contains(&"~/.gitconfig".to_string()));
+    assert!(effective.filesystem.allow_read.contains(&"~/.config/git/".to_string()));
+    assert!(effective.filesystem.allow_read.contains(&"~/.custom".to_string()));
+    assert!(effective.filesystem.allow_write.contains(&"~/.cache/".to_string()));
+    assert!(effective.filesystem.allow_write.contains(&"~/.custom-data/".to_string()));
+}
diff --git a/tests/profile_test.rs b/tests/profile_test.rs
index 932a62e..e6d772a 100644
--- a/tests/profile_test.rs
+++ b/tests/profile_test.rs
@@ -212,5 +212,51 @@ fn test_builtin_profile_from_name() {
         Some(BuiltinProfile::Claude)
     );
     assert_eq!(BuiltinProfile::from_name("gpg"), Some(BuiltinProfile::Gpg));
+    assert_eq!(
+        BuiltinProfile::from_name("opencode"),
+        Some(BuiltinProfile::Opencode)
+    );
     assert_eq!(BuiltinProfile::from_name("unknown"), None);
 }
+
+#[test]
+fn test_builtin_profile_opencode() {
+    let profile = BuiltinProfile::Opencode.load().unwrap();
+    assert_eq!(profile.network_mode, Some(NetworkMode::Online));
+    assert!(profile
+        .filesystem
+        .allow_read
+        .contains(&"~/.local/share/opencode".to_string()));
+    assert!(profile
+        .filesystem
+        .allow_read
+        .contains(&"~/.local/state/opencode".to_string()));
+    assert!(profile
+        .filesystem
+        .allow_read
+        .contains(&"~/.config/opencode".to_string()));
+    assert!(profile
+        .filesystem
+        .allow_read
+        .contains(&"~/.cache/opencode".to_string()));
+    assert!(profile
+        .filesystem
+        .allow_list_dirs
+        .contains(&"/private/tmp".to_string()));
+    assert!(profile
+        .filesystem
+        .allow_write
+        .contains(&"~/.config/opencode".to_string()));
+    assert!(profile
+        .filesystem
+        .allow_write
+        .contains(&"~/.local/share/opencode".to_string()));
+    assert!(profile
+        .filesystem
+        .allow_write
+        .contains(&"~/.local/state/opencode".to_string()));
+    assert!(profile
+        .filesystem
+        .allow_write
+        .contains(&"~/.cache/opencode".to_string()));
+}