diff --git a/app.yaml b/app.yaml
index 1a2fbc0..2b265f3 100644
--- a/app.yaml
+++ b/app.yaml
@@ -14,9 +14,19 @@ env:
     value: databricks-claude-opus-4-6
   - name: HERMES_FALLBACK_MODEL
     value: databricks-claude-opus-4-6
-  # Set ENABLE_HERMES=false to skip Hermes Agent install. Other CLIs are unaffected.
-  - name: ENABLE_HERMES
+  # Per-CLI install toggle. Defaults reflect a "least-trusted code in the App
+  # container" stance: Claude Code (Anthropic) and Codex (OpenAI) ship from
+  # vendors with mature signing/SBOM/advisory pipelines and are enabled by
+  # default. Gemini, OpenCode, and Hermes are opt-in — set ENABLE_<CLI>=true
+  # to install them. Claude Code is the primary CLI and isn't toggleable here.
+  - name: ENABLE_CODEX
     value: "true"
+  - name: ENABLE_OPENCODE
+    value: "false"
+  - name: ENABLE_GEMINI
+    value: "false"
+  - name: ENABLE_HERMES
+    value: "false"
   - name: CLAUDE_CODE_DISABLE_AUTO_MEMORY
     value: 0
   - name: MAX_CONCURRENT_SESSIONS
diff --git a/setup_codex.py b/setup_codex.py
index 6be864f..743a09c 100644
--- a/setup_codex.py
+++ b/setup_codex.py
@@ -15,6 +15,11 @@
 
 from utils import adapt_instructions_file, ensure_https, get_gateway_host, get_npm_version
 
+# Opt-out: allow operators to disable Codex bundling without removing the file.
+if os.environ.get("ENABLE_CODEX", "true").strip().lower() in ("false", "0", "no"):
+    print("ENABLE_CODEX=false — skipping Codex CLI setup")
+    raise SystemExit(0)
+
 # Set HOME if not properly set
 if not os.environ.get("HOME") or os.environ["HOME"] == "/":
     os.environ["HOME"] = "/app/python/source_code"
diff --git a/setup_gemini.py b/setup_gemini.py
index ec77851..8ced395 100644
--- a/setup_gemini.py
+++ b/setup_gemini.py
@@ -17,6 +17,11 @@
 
 from utils import adapt_instructions_file, ensure_https, get_gateway_host, get_npm_version
 
+# Opt-out: allow operators to disable Gemini bundling without removing the file.
+if os.environ.get("ENABLE_GEMINI", "true").strip().lower() in ("false", "0", "no"):
+    print("ENABLE_GEMINI=false — skipping Gemini CLI setup")
+    raise SystemExit(0)
+
 # Set HOME if not properly set
 if not os.environ.get("HOME") or os.environ["HOME"] == "/":
     os.environ["HOME"] = "/app/python/source_code"
diff --git a/setup_opencode.py b/setup_opencode.py
index 071252a..1ab6338 100644
--- a/setup_opencode.py
+++ b/setup_opencode.py
@@ -13,6 +13,11 @@
 
 from utils import ensure_https, get_gateway_host, get_npm_version
 
+# Opt-out: allow operators to disable OpenCode bundling without removing the file.
+if os.environ.get("ENABLE_OPENCODE", "true").strip().lower() in ("false", "0", "no"):
+    print("ENABLE_OPENCODE=false — skipping OpenCode CLI setup")
+    raise SystemExit(0)
+
 # content-filter proxy local proxy — sanitizes empty content blocks before reaching Databricks
 # (see https://github.com/sst/opencode/issues/5028)
 CONTENT_FILTER_PROXY_URL = "http://127.0.0.1:4000"