diff --git a/crates/bashkit/tests/allexport_tests.rs b/crates/bashkit/tests/allexport_tests.rs
new file mode 100644
index 00000000..a5e8162e
--- /dev/null
+++ b/crates/bashkit/tests/allexport_tests.rs
@@ -0,0 +1,171 @@
+//! Tests for `set -a` (allexport) behavior.
+//!
+//! When allexport is enabled, every variable assignment should also mark
+//! the variable as exported (visible to child scripts via env).
+
+use bashkit::Bash;
+use std::path::Path;
+
+/// Basic allexport: variables assigned while set -a is active are exported
+#[tokio::test]
+async fn allexport_basic_export_to_subprocess() {
+    let mut bash = Bash::new();
+    let fs = bash.fs();
+
+    fs.write_file(
+        Path::new("/check.sh"),
+        b"#!/bin/bash\necho \"FOO=${FOO:-unset}\"\necho \"BAZ=${BAZ:-unset}\"\necho \"AFTER=${AFTER:-unset}\"",
+    )
+    .await
+    .unwrap();
+    fs.chmod(Path::new("/check.sh"), 0o755).await.unwrap();
+
+    let result = bash
+        .exec(
+            r#"
+set -a
+FOO="bar"
+BAZ="qux"
+set +a
+AFTER="not-exported"
+/check.sh
+"#,
+        )
+        .await
+        .unwrap();
+
+    let lines: Vec<&str> = result.stdout.trim().lines().collect();
+    assert_eq!(lines[0], "FOO=bar");
+    assert_eq!(lines[1], "BAZ=qux");
+    assert_eq!(lines[2], "AFTER=unset");
+}
+
+/// allexport with source: sourced env files get exported
+#[tokio::test]
+async fn allexport_with_source() {
+    let mut bash = Bash::new();
+    let fs = bash.fs();
+
+    fs.write_file(Path::new("/vars.env"), b"DB_HOST=localhost\nDB_PORT=5432")
+        .await
+        .unwrap();
+
+    fs.write_file(
+        Path::new("/check.sh"),
+        b"#!/bin/bash\necho \"host=${DB_HOST:-unset}\"\necho \"port=${DB_PORT:-unset}\"",
+    )
+    .await
+    .unwrap();
+    fs.chmod(Path::new("/check.sh"), 0o755).await.unwrap();
+
+    let result = bash
+        .exec(
+            r#"
+set -a
+source /vars.env
+set +a
+/check.sh
+"#,
+        )
+        .await
+        .unwrap();
+
+    let lines: Vec<&str> = result.stdout.trim().lines().collect();
+    assert_eq!(lines[0], "host=localhost");
+    assert_eq!(lines[1], "port=5432");
+}
+
+/// set -o allexport / set +o allexport work as aliases
+#[tokio::test]
+async fn allexport_long_option_form() {
+    let mut bash = Bash::new();
+    let fs = bash.fs();
+
+    fs.write_file(
+        Path::new("/check.sh"),
+        b"#!/bin/bash\necho \"X=${X:-unset}\"\necho \"Y=${Y:-unset}\"",
+    )
+    .await
+    .unwrap();
+    fs.chmod(Path::new("/check.sh"), 0o755).await.unwrap();
+
+    let result = bash
+        .exec(
+            r#"
+set -o allexport
+X="hello"
+set +o allexport
+Y="world"
+/check.sh
+"#,
+        )
+        .await
+        .unwrap();
+
+    let lines: Vec<&str> = result.stdout.trim().lines().collect();
+    assert_eq!(lines[0], "X=hello");
+    assert_eq!(lines[1], "Y=unset");
+}
+
+/// Variables assigned before set -a are not retroactively exported
+#[tokio::test]
+async fn allexport_not_retroactive() {
+    let mut bash = Bash::new();
+    let fs = bash.fs();
+
+    fs.write_file(
+        Path::new("/check.sh"),
+        b"#!/bin/bash\necho \"BEFORE=${BEFORE:-unset}\"\necho \"DURING=${DURING:-unset}\"",
+    )
+    .await
+    .unwrap();
+    fs.chmod(Path::new("/check.sh"), 0o755).await.unwrap();
+
+    let result = bash
+        .exec(
+            r#"
+BEFORE="exists"
+set -a
+DURING="new"
+set +a
+/check.sh
+"#,
+        )
+        .await
+        .unwrap();
+
+    let lines: Vec<&str> = result.stdout.trim().lines().collect();
+    assert_eq!(lines[0], "BEFORE=unset");
+    assert_eq!(lines[1], "DURING=new");
+}
+
+/// allexport applies to for loop variable
+#[tokio::test]
+async fn allexport_for_loop_variable() {
+    let mut bash = Bash::new();
+    let fs = bash.fs();
+
+    fs.write_file(
+        Path::new("/check.sh"),
+        b"#!/bin/bash\necho \"item=${item:-unset}\"",
+    )
+    .await
+    .unwrap();
+    fs.chmod(Path::new("/check.sh"), 0o755).await.unwrap();
+
+    let result = bash
+        .exec(
+            r#"
+set -a
+for item in alpha beta; do
+  :
+done
+set +a
+/check.sh
+"#,
+        )
+        .await
+        .unwrap();
+
+    assert_eq!(result.stdout.trim(), "item=beta");
+}