diff --git a/src/basic_cli/cmd.sp b/src/basic_cli/cmd.sp
index 1e9770f..cc23a68 100644
--- a/src/basic_cli/cmd.sp
+++ b/src/basic_cli/cmd.sp
@@ -4,7 +4,7 @@
 
 /// Run a command and capture its stdout as a string.
 /// Returns the full stdout output on success.
-foreign fn process_run(cmd: String, args: List[String]) -> String ! ExecError uses [Spawn]
+pub foreign fn process_run(cmd: Str, args: List[Str]) -> Str ! ExecError uses [Spawn]
 
 /// Run a command and return its exit code.
-foreign fn process_run_status(cmd: String, args: List[String]) -> Int ! ExecError uses [Spawn]
+pub foreign fn process_run_status(cmd: Str, args: List[Str]) -> Int ! ExecError uses [Spawn]
diff --git a/src/basic_cli/dir.sp b/src/basic_cli/dir.sp
index e279873..22dc911 100644
--- a/src/basic_cli/dir.sp
+++ b/src/basic_cli/dir.sp
@@ -1,7 +1,7 @@
 /// basic-cli platform — Directory operations
 
 /// List entries in a directory, returning their names.
-foreign fn dir_list(path: String) -> List[String] ! IoError uses [FileRead]
+pub foreign fn dir_list(path: Str) -> List[Str] ! IoError uses [FileRead]
 
 /// Create a directory (and any missing parents).
-foreign fn dir_mkdir(path: String) -> Unit ! IoError uses [FileWrite]
+pub foreign fn dir_mkdir(path: Str) -> () ! IoError uses [FileWrite]
diff --git a/src/basic_cli/env.sp b/src/basic_cli/env.sp
index 22a6bb2..72f16ff 100644
--- a/src/basic_cli/env.sp
+++ b/src/basic_cli/env.sp
@@ -1,7 +1,7 @@
 /// basic-cli platform — Environment variable access
 
 /// Get the value of an environment variable, or None if not set.
-foreign fn env_get(key: String) -> Option[String] uses [Env]
+pub foreign fn env_get(key: Str) -> Option[Str] uses [Env]
 
 /// Set an environment variable.
-foreign fn env_set(key: String, value: String) -> Unit uses [Env]
+pub foreign fn env_set(key: Str, value: Str) -> () uses [Env]
diff --git a/src/basic_cli/file.sp b/src/basic_cli/file.sp
index 0d40000..cea3eb8 100644
--- a/src/basic_cli/file.sp
+++ b/src/basic_cli/file.sp
@@ -3,13 +3,13 @@
 /// Provides capability-gated file read and write operations.
 
 /// Read the entire contents of a file as a string.
-foreign fn file_read(path: String) -> String ! IoError uses [FileRead]
+pub foreign fn file_read(path: Str) -> Str ! IoError uses [FileRead]
 
 /// Write content to a file, creating or overwriting it.
-foreign fn file_write(path: String, content: String) -> Unit ! IoError uses [FileWrite]
+pub foreign fn file_write(path: Str, content: Str) -> () ! IoError uses [FileWrite]
 
 /// Check whether a file or directory exists at the given path.
-foreign fn file_exists(path: String) -> Bool uses [FileRead]
+pub foreign fn file_exists(path: Str) -> Bool uses [FileRead]
 
 /// Get file metadata (size, modified time, etc.) as a string representation.
-foreign fn file_stat(path: String) -> String ! IoError uses [FileRead]
+pub foreign fn file_stat(path: Str) -> Str ! IoError uses [FileRead]
diff --git a/src/basic_cli/stdin.sp b/src/basic_cli/stdin.sp
index 7e86f64..1802154 100644
--- a/src/basic_cli/stdin.sp
+++ b/src/basic_cli/stdin.sp
@@ -1,4 +1,4 @@
 /// basic-cli platform — Standard input operations
 
 /// Read a line from stdin (blocks until newline).
-foreign fn read_line() -> String uses [Console]
+pub foreign fn read_line() -> Str ! IoError uses [Console]
diff --git a/src/basic_cli/stdout.sp b/src/basic_cli/stdout.sp
index 3c1b05b..99308a1 100644
--- a/src/basic_cli/stdout.sp
+++ b/src/basic_cli/stdout.sp
@@ -3,13 +3,13 @@
 /// Provides capability-gated access to stdout/stderr.
 
 /// Print a string to stdout without trailing newline.
-foreign fn print(s: String) -> Unit uses [Console]
+pub foreign fn print(s: Str) -> () ! IoError uses [Console]
 
 /// Print a string to stdout with trailing newline.
-foreign fn println(s: String) -> Unit uses [Console]
+pub foreign fn println(s: Str) -> () uses [Console]
 
 /// Print a formatted string to stderr.
-foreign fn eprint(s: String) -> Unit uses [Console]
+pub foreign fn eprint(s: Str) -> () ! IoError uses [Console]
 
 /// Print a formatted string to stderr with trailing newline.
-foreign fn eprintln(s: String) -> Unit uses [Console]
+pub foreign fn eprintln(s: Str) -> () uses [Console]