fix(interpreter): get_ifs_separator respects local IFS (#902)

## Summary

- `get_ifs_separator()` only checked `self.variables` for IFS, missing
local IFS declarations stored in `call_stack.locals`. This caused `local
IFS=":"` to have no effect on `"${arr[*]}"` array joining inside
functions.
- Fix: use `expand_variable("IFS")` which checks locals first, with
proper handling of unset vs empty IFS.
- Includes regression test.

## Test plan

- [x] `cargo test --all-features -p bashkit --lib` — all 2123 tests pass
- [x] `cargo clippy --all-targets --all-features -- -D warnings` — clean
- [x] `cargo fmt --check` — clean
- [x] Regression test `test_local_ifs_array_join` covers the exact bug

Author: chaliy

crates/bashkit/src/interpreter/mod.rs

@@ -7980,13 +7980,16 @@ impl Interpreter {
 
     /// Get the separator for `[*]` array joins: first char of IFS, or space if IFS unset.
     fn get_ifs_separator(&self) -> String {
-        match self.variables.get("IFS") {
-            Some(ifs) => ifs
-                .chars()
+        let ifs = self.expand_variable("IFS");
+        if ifs.is_empty() && !self.is_variable_set("IFS") {
+            // IFS unset: default separator is space
+            " ".to_string()
+        } else {
+            // IFS set (possibly empty): first char or empty
+            ifs.chars()
                 .next()
                 .map(|c| c.to_string())
-                .unwrap_or_default(),
-            None => " ".to_string(),
+                .unwrap_or_default()
         }
     }
 

crates/bashkit/src/lib.rs

@@ -2485,6 +2485,26 @@ fn
         assert_eq!(result.stdout, "test\n");
     }
 
+    #[tokio::test]
+    async fn test_local_ifs_array_join() {
+        // Regression: local IFS=":" must affect "${arr[*]}" joining
+        let mut bash = Bash::new();
+        let result = bash
+            .exec(
+                r#"
+fn() {
+  local arr=(a b c)
+  local IFS=":"
+  echo "${arr[*]}"
+}
+fn
+"#,
+            )
+            .await
+            .unwrap();
+        assert_eq!(result.stdout, "a:b:c\n");
+    }
+
     #[tokio::test]
     async fn test_glob_star() {
         let mut bash = Bash::new();

supply-chain/config.toml

@@ -575,7 +575,7 @@ version = "2.13.0"
 criteria = "safe-to-deploy"
 
 [[exemptions.insta]]
-version = "1.47.1"
+version = "1.47.2"
 criteria = "safe-to-run"
 
 [[exemptions.instant]]