diff --git a/crates/openshell-sandbox/src/lib.rs b/crates/openshell-sandbox/src/lib.rs
index 493e4d23..1d6ac275 100644
--- a/crates/openshell-sandbox/src/lib.rs
+++ b/crates/openshell-sandbox/src/lib.rs
@@ -202,7 +202,25 @@ pub async fn run_sandbox(
         std::collections::HashMap::new()
     };
 
-    let (provider_env, secret_resolver) = SecretResolver::from_provider_env(provider_env);
+    // Use the placeholder mechanism only when the policy has at least one
+    // `tls: terminate` endpoint. Without TLS termination the proxy cannot
+    // intercept HTTPS traffic to rewrite credential placeholders in request
+    // headers, so placeholder values would reach upstream APIs verbatim and
+    // cause 401 errors. When no such endpoint exists, pass real credentials
+    // directly so API calls succeed.
+    let (provider_env, secret_resolver) = if policy.has_tls_terminate_endpoints {
+        SecretResolver::from_provider_env(provider_env)
+    } else {
+        if !provider_env.is_empty() {
+            warn!(
+                "Sandbox policy has no `tls: terminate` endpoints; \
+                 provider credentials are passed directly to the child process. \
+                 Add `protocol: rest` and `tls: terminate` to HTTPS endpoints \
+                 that use provider credentials to enable secure credential rewriting."
+            );
+        }
+        (provider_env, None)
+    };
     let secret_resolver = secret_resolver.map(Arc::new);
 
     // Create identity cache for SHA256 TOFU when OPA is active
@@ -981,6 +999,9 @@ async fn load_policy(
             },
             landlock: config.landlock,
             process: config.process,
+            // File-mode is a dev/operator override — assume the operator has
+            // configured `tls: terminate` where needed.
+            has_tls_terminate_endpoints: true,
         };
         enrich_sandbox_baseline_paths(&mut policy);
         return Ok((policy, Some(Arc::new(engine))));
diff --git a/crates/openshell-sandbox/src/policy.rs b/crates/openshell-sandbox/src/policy.rs
index 0827fa0d..c90e7872 100644
--- a/crates/openshell-sandbox/src/policy.rs
+++ b/crates/openshell-sandbox/src/policy.rs
@@ -17,6 +17,13 @@ pub struct SandboxPolicy {
     pub network: NetworkPolicy,
     pub landlock: LandlockPolicy,
     pub process: ProcessPolicy,
+    /// True when at least one network endpoint has `tls: terminate` configured.
+    ///
+    /// When false, the proxy cannot rewrite credential placeholder values in
+    /// HTTP headers (TLS MITM is required for that). Provider credentials are
+    /// passed directly to the child process instead of using the placeholder
+    /// mechanism so that API calls succeed.
+    pub has_tls_terminate_endpoints: bool,
 }
 
 #[derive(Debug, Clone)]
@@ -106,6 +113,12 @@ impl TryFrom<ProtoSandboxPolicy> for SandboxPolicy {
             proxy: Some(ProxyPolicy { http_addr: None }),
         };
 
+        let has_tls_terminate_endpoints = proto
+            .network_policies
+            .values()
+            .flat_map(|r| r.endpoints.iter())
+            .any(|ep| ep.tls == "terminate");
+
         Ok(Self {
             version: proto.version,
             filesystem: proto
@@ -115,6 +128,7 @@ impl TryFrom<ProtoSandboxPolicy> for SandboxPolicy {
             network,
             landlock: proto.landlock.map(LandlockPolicy::from).unwrap_or_default(),
             process: proto.process.map(ProcessPolicy::from).unwrap_or_default(),
+            has_tls_terminate_endpoints,
         })
     }
 }
diff --git a/crates/openshell-sandbox/src/process.rs b/crates/openshell-sandbox/src/process.rs
index b93d125a..790c426f 100644
--- a/crates/openshell-sandbox/src/process.rs
+++ b/crates/openshell-sandbox/src/process.rs
@@ -524,6 +524,7 @@ mod tests {
             network: NetworkPolicy::default(),
             landlock: LandlockPolicy::default(),
             process,
+            has_tls_terminate_endpoints: false,
         }
     }
 
diff --git a/crates/openshell-sandbox/testdata/sandbox-policy.yaml b/crates/openshell-sandbox/testdata/sandbox-policy.yaml
index 76ad39b2..70e71177 100644
--- a/crates/openshell-sandbox/testdata/sandbox-policy.yaml
+++ b/crates/openshell-sandbox/testdata/sandbox-policy.yaml
@@ -33,7 +33,12 @@ network_policies:
   claude_code:
     name: claude_code
     endpoints:
-      - { host: api.anthropic.com, port: 443 }
+      - host: api.anthropic.com
+        port: 443
+        protocol: rest
+        tls: terminate
+        enforcement: enforce
+        access: full
       - { host: statsig.anthropic.com, port: 443 }
     binaries:
       - { path: /usr/local/bin/claude }