diff --git a/docs/STDLIB_REFERENCE.md b/docs/STDLIB_REFERENCE.md
index ca9a29e..5f17951 100644
--- a/docs/STDLIB_REFERENCE.md
+++ b/docs/STDLIB_REFERENCE.md
@@ -6661,7 +6661,7 @@ cache_fetch(cache_obj: Map, url_or_options: String | Map) -> Result<Response, St
 
 Fetch a URL using a cache, returning a cached response if available.
 
-Checks the cache for a previously stored response matching the URL. On a cache miss, performs the HTTP request via fetch(), stores the successful response in the cache, and returns it. This is the internal function backing cache.fetch() method calls.
+Checks the cache for a previously stored response matching the URL. Secret-bearing request options are rejected because cache keys do not include credentials. On a cache miss, performs the HTTP request via fetch(), stores the successful response in the cache, and returns it. This is the internal function backing cache.fetch() method calls.
 
 **Parameters:**
 
diff --git a/src/stdlib/concurrent.rs b/src/stdlib/concurrent.rs
index 0b9b8c9..cdc8b24 100644
--- a/src/stdlib/concurrent.rs
+++ b/src/stdlib/concurrent.rs
@@ -3013,6 +3013,22 @@ mod tests {
         }
     }
 
+    #[test]
+    fn serialized_values_reject_secrets_across_task_and_channel_boundaries() {
+        let canary = "concurrent-secret-canary";
+        let value = Value::Map(HashMap::from([(
+            "token".to_string(),
+            Value::Secret(
+                crate::interpreter::SecretValue::new("CONCURRENT_SECRET", canary)
+                    .expect("valid secret"),
+            ),
+        )]));
+
+        let error = SerializedValue::from_value(&value)
+            .expect_err("task and channel serialization must reject secrets");
+        assert!(!error.to_string().contains(canary));
+    }
+
     #[test]
     fn test_module_init() {
         let module = init();
diff --git a/src/stdlib/http.rs b/src/stdlib/http.rs
index 17568eb..8e763bd 100644
--- a/src/stdlib/http.rs
+++ b/src/stdlib/http.rs
@@ -339,6 +339,13 @@ fn cached_response_to_value(resp: &CachedResponse) -> Value {
 }
 
 fn cache_fetch(cache_id: u64, url: &str, opts: Option<&HashMap<String, Value>>) -> Result<Value> {
+    if opts.is_some_and(|options| options.values().any(Value::contains_secret)) {
+        return Err(IntentError::type_error(
+            "cache_fetch() cannot cache responses for secret-bearing requests; use fetch() directly"
+                .to_string(),
+        ));
+    }
+
     // Check cache first
     {
         let mut registry = CACHE_REGISTRY.lock().unwrap();
@@ -1092,6 +1099,7 @@ pub fn init() -> HashMap<String, Value> {
     // Fetch a URL using a cache, returning a cached response if available.
     //
     // Checks the cache for a previously stored response matching the URL.
+    // Secret-bearing request options are rejected because cache keys do not include credentials.
     // On a cache miss, performs the HTTP request via fetch(), stores the
     // successful response in the cache, and returns it. This is the internal
     // function backing cache.fetch() method calls.
@@ -1233,3 +1241,33 @@ pub fn init() -> HashMap<String, Value> {
 
     module
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn cache_fetch_rejects_secret_bearing_options_before_cache_lookup() {
+        let canary = "cache-secret-canary";
+        let options = HashMap::from([
+            (
+                "url".to_string(),
+                Value::String("http://127.0.0.1:1/never-requested".to_string()),
+            ),
+            (
+                "headers".to_string(),
+                Value::Map(HashMap::from([(
+                    "Authorization".to_string(),
+                    Value::Secret(
+                        crate::interpreter::SecretValue::new("CACHE_SECRET", canary)
+                            .expect("valid secret"),
+                    ),
+                )])),
+            ),
+        ]);
+
+        let error = cache_fetch(0, "http://127.0.0.1:1/never-requested", Some(&options))
+            .expect_err("secret-bearing requests must not use the response cache");
+        assert!(!error.to_string().contains(canary));
+    }
+}
diff --git a/src/stdlib/postgres.rs b/src/stdlib/postgres.rs
index bf1f9a8..2fdb4c2 100644
--- a/src/stdlib/postgres.rs
+++ b/src/stdlib/postgres.rs
@@ -156,8 +156,14 @@ impl ToSql for SqlParam {
 }
 
 /// Convert an Intent Value to a SQL parameter
-fn value_to_sql_param(value: &Value) -> SqlParam {
-    match value {
+fn value_to_sql_param(value: &Value) -> Result<SqlParam> {
+    if value.contains_secret() {
+        return Err(IntentError::type_error(
+            "PostgreSQL parameters cannot contain Secret values".to_string(),
+        ));
+    }
+
+    Ok(match value {
         Value::Int(i) => {
             // Use i32 for smaller values, i64 for larger
             if *i >= i32::MIN as i64 && *i <= i32::MAX as i64 {
@@ -206,7 +212,7 @@ fn value_to_sql_param(value: &Value) -> SqlParam {
             }
         }
         _ => SqlParam::String(format!("{}", value)), // Fallback to string representation
-    }
+    })
 }
 
 /// Convert a tokio-postgres row to an Intent Map
@@ -819,7 +825,10 @@ async fn pg_execute_cached(
 
 /// Execute a query using either the transaction client or a fresh pool connection
 fn pg_query(conn: &Value, sql: &str, params: &[Value]) -> Result<Value> {
-    let sql_params: Vec<SqlParam> = params.iter().map(value_to_sql_param).collect();
+    let sql_params: Vec<SqlParam> = params
+        .iter()
+        .map(value_to_sql_param)
+        .collect::<Result<_>>()?;
     let param_refs: Vec<&(dyn ToSql + Sync)> = sql_params
         .iter()
         .map(|p| p as &(dyn ToSql + Sync))
@@ -869,7 +878,10 @@ fn pg_query(conn: &Value, sql: &str, params: &[Value]) -> Result<Value> {
 
 /// Execute a query and return a single row (or null)
 fn pg_query_one(conn: &Value, sql: &str, params: &[Value]) -> Result<Value> {
-    let sql_params: Vec<SqlParam> = params.iter().map(value_to_sql_param).collect();
+    let sql_params: Vec<SqlParam> = params
+        .iter()
+        .map(value_to_sql_param)
+        .collect::<Result<_>>()?;
     let param_refs: Vec<&(dyn ToSql + Sync)> = sql_params
         .iter()
         .map(|p| p as &(dyn ToSql + Sync))
@@ -913,7 +925,10 @@ fn pg_query_one(conn: &Value, sql: &str, params: &[Value]) -> Result<Value> {
 
 /// Execute a statement (INSERT/UPDATE/DELETE) and return affected row count
 fn pg_execute(conn: &Value, sql: &str, params: &[Value]) -> Result<Value> {
-    let sql_params: Vec<SqlParam> = params.iter().map(value_to_sql_param).collect();
+    let sql_params: Vec<SqlParam> = params
+        .iter()
+        .map(value_to_sql_param)
+        .collect::<Result<_>>()?;
     let param_refs: Vec<&(dyn ToSql + Sync)> = sql_params
         .iter()
         .map(|p| p as &(dyn ToSql + Sync))
@@ -1473,27 +1488,39 @@ mod tests {
     #[test]
     fn test_value_to_sql_param() {
         // Test integer conversion
-        let param = value_to_sql_param(&Value::Int(42));
+        let param = value_to_sql_param(&Value::Int(42)).expect("integer parameter");
         match param {
             SqlParam::Int(v) => assert_eq!(v, 42),
             _ => panic!("Expected Int"),
         }
 
         // Test boolean conversion
-        let param = value_to_sql_param(&Value::Bool(true));
+        let param = value_to_sql_param(&Value::Bool(true)).expect("boolean parameter");
         match param {
             SqlParam::Bool(v) => assert!(v),
             _ => panic!("Expected Bool"),
         }
 
         // Test string conversion
-        let param = value_to_sql_param(&Value::String("test".to_string()));
+        let param =
+            value_to_sql_param(&Value::String("test".to_string())).expect("string parameter");
         match param {
             SqlParam::String(v) => assert_eq!(v, "test"),
             _ => panic!("Expected String"),
         }
     }
 
+    #[test]
+    fn secret_values_are_rejected_from_postgres_parameters() {
+        let canary = "postgres-secret-canary";
+        let value = Value::Array(vec![Value::Secret(
+            crate::interpreter::SecretValue::new("POSTGRES_SECRET", canary).expect("valid secret"),
+        )]);
+
+        let error = value_to_sql_param(&value).expect_err("PostgreSQL must reject secrets");
+        assert!(!error.to_string().contains(canary));
+    }
+
     #[test]
     fn test_pg_query_cached_recovers_from_stale_result_plan() {
         let Some(url) = std::env::var("NTNT_POSTGRES_TEST_URL")
diff --git a/src/stdlib/sqlite.rs b/src/stdlib/sqlite.rs
index 0739c7a..60ea1db 100644
--- a/src/stdlib/sqlite.rs
+++ b/src/stdlib/sqlite.rs
@@ -29,8 +29,14 @@ static CONNECTION_REGISTRY: std::sync::LazyLock<Mutex<HashMap<u64, Arc<Mutex<Con
 static CONNECTION_ID_COUNTER: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::new(1);
 
 /// Convert an Intent Value to a rusqlite Value
-fn value_to_sqlite(value: &Value) -> rusqlite::types::Value {
-    match value {
+fn value_to_sqlite(value: &Value) -> Result<rusqlite::types::Value> {
+    if value.contains_secret() {
+        return Err(IntentError::type_error(
+            "SQLite parameters cannot contain Secret values".to_string(),
+        ));
+    }
+
+    Ok(match value {
         Value::Int(i) => rusqlite::types::Value::Integer(*i),
         Value::Float(f) => rusqlite::types::Value::Real(*f),
         Value::String(s) => rusqlite::types::Value::Text(s.clone()),
@@ -40,7 +46,7 @@ fn value_to_sqlite(value: &Value) -> rusqlite::types::Value {
             enum_name, variant, ..
         } if enum_name == "Option" && variant == "None" => rusqlite::types::Value::Null,
         _ => rusqlite::types::Value::Text(format!("{}", value)),
-    }
+    })
 }
 
 /// Convert a SQLite ValueRef to an Intent Value
@@ -121,7 +127,8 @@ fn sqlite_query(conn: &Value, sql: &str, params: &[Value]) -> Result<Value> {
         .lock()
         .map_err(|e| IntentError::runtime_error(format!("Failed to lock connection: {}", e)))?;
 
-    let sqlite_params: Vec<rusqlite::types::Value> = params.iter().map(value_to_sqlite).collect();
+    let sqlite_params: Vec<rusqlite::types::Value> =
+        params.iter().map(value_to_sqlite).collect::<Result<_>>()?;
 
     let mut stmt = conn_guard
         .prepare(sql)
@@ -162,7 +169,8 @@ fn sqlite_query_one(conn: &Value, sql: &str, params: &[Value]) -> Result<Value>
         .lock()
         .map_err(|e| IntentError::runtime_error(format!("Failed to lock connection: {}", e)))?;
 
-    let sqlite_params: Vec<rusqlite::types::Value> = params.iter().map(value_to_sqlite).collect();
+    let sqlite_params: Vec<rusqlite::types::Value> =
+        params.iter().map(value_to_sqlite).collect::<Result<_>>()?;
 
     let mut stmt = conn_guard
         .prepare(sql)
@@ -193,7 +201,8 @@ fn sqlite_execute(conn: &Value, sql: &str, params: &[Value]) -> Result<Value> {
         .lock()
         .map_err(|e| IntentError::runtime_error(format!("Failed to lock connection: {}", e)))?;
 
-    let sqlite_params: Vec<rusqlite::types::Value> = params.iter().map(value_to_sqlite).collect();
+    let sqlite_params: Vec<rusqlite::types::Value> =
+        params.iter().map(value_to_sqlite).collect::<Result<_>>()?;
 
     match conn_guard.execute(sql, rusqlite::params_from_iter(sqlite_params.iter())) {
         Ok(count) => Ok(Value::ok(Value::Int(count as i64))),
@@ -937,36 +946,51 @@ mod tests {
 
     #[test]
     fn test_value_to_sqlite_conversion() {
-        match value_to_sqlite(&Value::Int(42)) {
+        match value_to_sqlite(&Value::Int(42)).expect("integer parameter") {
             rusqlite::types::Value::Integer(v) => assert_eq!(v, 42),
             _ => panic!("Expected Integer"),
         }
-        match value_to_sqlite(&Value::Float(3.14)) {
+        match value_to_sqlite(&Value::Float(3.14)).expect("float parameter") {
             rusqlite::types::Value::Real(v) => assert!((v - 3.14).abs() < f64::EPSILON),
             _ => panic!("Expected Real"),
         }
-        match value_to_sqlite(&Value::String("hello".to_string())) {
+        match value_to_sqlite(&Value::String("hello".to_string())).expect("string parameter") {
             rusqlite::types::Value::Text(v) => assert_eq!(v, "hello"),
             _ => panic!("Expected Text"),
         }
-        match value_to_sqlite(&Value::Bool(true)) {
+        match value_to_sqlite(&Value::Bool(true)).expect("boolean parameter") {
             rusqlite::types::Value::Integer(v) => assert_eq!(v, 1),
             _ => panic!("Expected Integer for true"),
         }
-        match value_to_sqlite(&Value::Bool(false)) {
+        match value_to_sqlite(&Value::Bool(false)).expect("boolean parameter") {
             rusqlite::types::Value::Integer(v) => assert_eq!(v, 0),
             _ => panic!("Expected Integer for false"),
         }
-        match value_to_sqlite(&Value::Unit) {
+        match value_to_sqlite(&Value::Unit).expect("unit parameter") {
             rusqlite::types::Value::Null => {}
             _ => panic!("Expected Null for Unit"),
         }
-        match value_to_sqlite(&Value::none()) {
+        match value_to_sqlite(&Value::none()).expect("none parameter") {
             rusqlite::types::Value::Null => {}
             _ => panic!("Expected Null for None"),
         }
     }
 
+    #[test]
+    fn secret_values_are_rejected_from_sqlite_parameters() {
+        let canary = "sqlite-secret-canary";
+        let value = Value::Map(HashMap::from([(
+            "token".to_string(),
+            Value::Secret(
+                crate::interpreter::SecretValue::new("SQLITE_SECRET", canary)
+                    .expect("valid secret"),
+            ),
+        )]));
+
+        let error = value_to_sqlite(&value).expect_err("SQLite must reject secrets");
+        assert!(!error.to_string().contains(canary));
+    }
+
     #[test]
     fn test_error_on_invalid_sql() {
         let conn = match sqlite_connect(":memory:").unwrap() {