diff --git a/tests/rust/wasm32-wasip3/src/bin/http-fields.rs b/tests/rust/wasm32-wasip3/src/bin/http-fields.rs
new file mode 100644
index 00000000..90c5906b
--- /dev/null
+++ b/tests/rust/wasm32-wasip3/src/bin/http-fields.rs
@@ -0,0 +1,327 @@
+extern crate wit_bindgen;
+
+wit_bindgen::generate!({
+    inline: r"
+  package test:test;
+
+  world test {
+      include wasi:http/imports@0.3.0-rc-2025-09-16;
+      include wasi:cli/command@0.3.0-rc-2025-09-16;
+  }
+",
+    additional_derives: [PartialEq, Eq, Hash, Clone],
+    features:["clocks-timezone"],
+    generate_all
+});
+
+use wasi::http::types::Fields;
+use wasi::http::types::HeaderError;
+
+fn test_empty_fields_inner(fields: Fields) {
+    assert!(!fields.has("foo"));
+    assert!(fields.get("foo").is_empty());
+    assert!(fields.get_and_delete("foo").unwrap().is_empty());
+    fields.delete("foo").unwrap();
+    fields.delete("other").unwrap();
+    assert!(fields.copy_all().is_empty());
+}
+
+fn test_empty_fields() {
+    let fields = Fields::new();
+    let clone = fields.clone();
+    test_empty_fields_inner(fields);
+    test_empty_fields_inner(clone);
+    test_empty_fields_inner(Fields::from_list(&[]).unwrap());
+}
+
+fn test_fields_with_foo_inner(fields: Fields) {
+    assert!(fields.has("foo"));
+    assert_eq!(fields.get("foo"), [b"bar".to_vec()]);
+    fields.delete("foo").unwrap();
+    assert!(!fields.has("foo"));
+    assert!(fields.get("foo").is_empty());
+
+    fields.set("foo", &[]).unwrap();
+    assert!(!fields.has("foo"));
+    assert!(fields.get("foo").is_empty());
+    fields.set("foo", &[b"bar".to_vec(),
+                        b"baz".to_vec()]).unwrap();
+    assert!(fields.has("foo"));
+    assert_eq!(fields.get("foo"), [b"bar".to_vec(),
+                                   b"baz".to_vec()]);
+    assert_eq!(fields.get_and_delete("foo").unwrap(),
+               [b"bar".to_vec(), b"baz".to_vec()]);
+    assert!(fields.get_and_delete("foo").unwrap().is_empty());
+
+    fields.set("foo", &[b"bar".to_vec(), b"baz".to_vec()]).unwrap();
+    assert!(fields.has("foo"));
+    assert_eq!(fields.get("foo"), [b"bar".to_vec(),
+                                   b"baz".to_vec()]);
+    assert_eq!(fields.get_and_delete("foo").unwrap(),
+               [b"bar".to_vec(), b"baz".to_vec()]);
+    assert!(fields.get_and_delete("foo").unwrap().is_empty());
+    assert!(!fields.has("foo"));
+
+    fields.append("foo", b"bar").unwrap();
+    fields.append("foo", b"baz").unwrap();
+    assert!(fields.has("foo"));
+    assert_eq!(fields.get("foo"), [b"bar".to_vec(),
+                                   b"baz".to_vec()]);
+    assert_eq!(fields.get_and_delete("foo").unwrap(),
+               [b"bar".to_vec(), b"baz".to_vec()]);
+    assert!(fields.get_and_delete("foo").unwrap().is_empty());
+    assert!(!fields.has("foo"));
+}
+
+fn test_fields_with_foo() {
+    let fields = Fields::from_list(&[("foo".to_string(),
+                                      b"bar".to_vec())]).unwrap();
+    let clone = fields.clone();
+    test_fields_with_foo_inner(fields);
+    test_fields_with_foo_inner(clone);
+}
+
+fn test_invalid_field_name(field: &str) {
+    let fields = Fields::new();
+    assert!(!fields.has(field));
+    assert!(fields.get(field).is_empty());
+    assert_eq!(fields.delete(field),
+               Err(HeaderError::InvalidSyntax));
+    assert_eq!(fields.get_and_delete(field),
+               Err(HeaderError::InvalidSyntax));
+    assert_eq!(fields.set(field, &[b"val".to_vec()]),
+               Err(HeaderError::InvalidSyntax));
+    assert_eq!(fields.append(field, b"val"),
+               Err(HeaderError::InvalidSyntax));
+    assert!(fields.copy_all().is_empty());
+    assert!(!fields.has(field));
+    assert!(fields.get(field).is_empty());
+
+    assert_eq!(Fields::from_list(&[(field.to_string(), b"val".to_vec())])
+               .unwrap_err(),
+               HeaderError::InvalidSyntax);
+}
+
+fn test_valid_field_name(field: &str) {
+    let fields = Fields::new();
+    assert!(!fields.has(field));
+    assert!(fields.get(field).is_empty());
+    fields.delete(field).unwrap();
+    assert!(fields.get_and_delete(field).unwrap().is_empty());
+    fields.set(field, &[b"val".to_vec()]).unwrap();
+    fields.append(field, b"val2").unwrap();
+    assert_eq!(fields.copy_all(),
+               [(field.to_string(), b"val".to_vec()),
+                (field.to_string(), b"val2".to_vec())]);
+    assert_eq!(Fields::from_list(&[(field.to_string(), b"val".to_vec()),
+                                   (field.to_string(), b"val2".to_vec())])
+               .unwrap().copy_all(),
+               fields.clone().copy_all());
+}
+
+fn test_invalid_field_value(val: &[u8]) {
+    let fields = Fields::new();
+    assert_eq!(fields.set("foo", &[val.to_vec()]),
+               Err(HeaderError::InvalidSyntax));
+    assert_eq!(fields.append("foo", val),
+               Err(HeaderError::InvalidSyntax));
+    assert_eq!(Fields::from_list(&[("foo".to_string(), val.to_vec())])
+               .unwrap_err(),
+               HeaderError::InvalidSyntax);
+}
+
+fn test_valid_field_value(val: &[u8]) {
+    let fields = Fields::new();
+    fields.set("foo", &[val.to_vec()]).unwrap();
+    fields.append("foo", val).unwrap();
+    assert_eq!(fields.copy_all(),
+               [("foo".to_string(), val.to_vec()),
+                ("foo".to_string(), val.to_vec())]);
+    assert_eq!(Fields::from_list(&[("foo".to_string(), val.to_vec()),
+                                   ("foo".to_string(), val.to_vec())])
+               .unwrap().copy_all(),
+               fields.clone().copy_all());
+}
+
+fn compute_valid_field_name_chars(len: usize) -> Vec<bool> {
+    // https://www.rfc-editor.org/rfc/rfc9110.html#section-5.6.2
+    //  field-name     = token
+    //  token          = 1*tchar
+    //
+    //  tchar          = "!" / "#" / "$" / "%" / "&" / "'" / "*"
+    //                 / "+" / "-" / "." / "^" / "_" / "`" / "|" / "~"
+    //                 / DIGIT / ALPHA
+    //                 ; any VCHAR, except delimiters
+    let mut ret = Vec::<bool>::new();
+    ret.resize(len, false);
+    for ch in "!#$%&'*+-.^_`|~".chars() {
+        ret[ch as usize] = true;
+    }
+    for ch in 'a'..='z' {
+        ret[ch as usize] = true;
+    }
+    for ch in 'A'..='Z' {
+        ret[ch as usize] = true;
+    }
+    for ch in '0'..='9' {
+        ret[ch as usize] = true;
+    }
+    ret
+}
+
+fn test_invalid_field_names() {
+    test_invalid_field_name("");
+    test_invalid_field_name("voilà");
+    test_invalid_field_name("hey ho");
+    test_invalid_field_name(" ");
+    test_invalid_field_name(" hey");
+    test_invalid_field_name("hey ");
+    test_invalid_field_name("(what)");
+    test_invalid_field_name("[what]");
+    test_invalid_field_name("{what}");
+    // https://github.com/bytecodealliance/wasmtime/issues/11771
+    // test_invalid_field_name("\"foo\"");
+    let max_codepoint_to_test = 1024;
+    let valid = compute_valid_field_name_chars(max_codepoint_to_test);
+    for ch in 0..max_codepoint_to_test {
+        if !valid[ch] {
+            let ch = char::from_u32(ch as u32).unwrap();
+            if ch == '"' {
+                // https://github.com/bytecodealliance/wasmtime/issues/11771
+                continue;
+            }
+            test_invalid_field_name(&String::from(ch));
+        }
+    }
+}
+
+fn test_valid_field_names() {
+    let max_codepoint_to_test = 1024;
+    let valid = compute_valid_field_name_chars(max_codepoint_to_test);
+    for ch in 0..max_codepoint_to_test {
+        if valid[ch] {
+            let ch = char::from_u32(ch as u32).unwrap();
+            if ch.is_uppercase() {
+                // https://github.com/bytecodealliance/wasmtime/issues/11770
+                continue;
+            }
+            test_valid_field_name(&String::from(ch));
+        }
+    }
+
+    test_valid_field_name("1");
+    test_valid_field_name("142");
+    // https://github.com/bytecodealliance/wasmtime/issues/11770
+    // test_valid_field_name("Foo");
+    // test_valid_field_name("ConnectionLevel142");
+    test_valid_field_name("kebab-data-100");
+    test_valid_field_name(str::from_utf8(&[b"f"[0]; 1024]).unwrap());
+}
+
+fn compute_valid_field_value_bytes() -> Vec<bool> {
+    // https://www.rfc-editor.org/rfc/rfc9110.html#section-5.6.2
+    //  field-value    = *field-content
+    //  field-content  = field-vchar
+    //                   [ 1*( SP / HTAB / field-vchar ) field-vchar ]
+    //  field-vchar    = VCHAR / obs-text
+    //  VCHAR          = %x21-7E
+    //  obs-text       = %x80-FF
+    let mut ret = Vec::<bool>::new();
+    ret.resize(256, false);
+    ret[' ' as usize] = true;
+    ret['\t' as usize] = true;
+    for ch in 0x21..=0x7e {
+        ret[ch] = true;
+    }
+    for ch in 0x80..=0xff {
+        ret[ch] = true;
+    }
+    ret
+}
+
+fn test_invalid_field_values() {
+    let valid = compute_valid_field_value_bytes();
+    for byte in 0u8..=0xff {
+        if !valid[byte as usize] {
+            test_invalid_field_value(&[byte]);
+        }
+    }
+
+    test_invalid_field_value(b"\n");
+    test_invalid_field_value(b"\r");
+    test_invalid_field_value(b"\0");
+}
+
+fn test_valid_field_values() {
+    let valid = compute_valid_field_value_bytes();
+    for byte in 0u8..=0xff {
+        if valid[byte as usize] {
+            test_valid_field_value(&[byte])
+        }
+    }
+
+    test_valid_field_value(b"");
+    test_valid_field_value(b" \t \t \t \t \t ");
+    test_valid_field_value(b"Foo");
+    test_valid_field_value(b"ConnectionLevel142");
+    test_valid_field_value(b"kebab-data-100");
+    test_valid_field_value(&[b"f"[0]; 1024]);
+}
+
+fn test_field_name_case_insensitivity() {
+    let lower = "foo";
+    let upper = "FOO";
+    
+    let fields = Fields::new();
+    fields.append(lower, b"val1").unwrap();
+    assert!(fields.has(lower));
+    assert!(fields.has(upper));
+    assert_eq!(fields.get(lower), fields.get(upper));
+    fields.delete(upper).unwrap();
+    assert!(!fields.has(lower));
+    assert!(!fields.has(upper));
+
+    fields.append(upper, b"val1").unwrap();
+    assert!(fields.has(upper));
+    assert!(fields.has(lower));
+    assert_eq!(fields.get(lower), fields.get(upper));
+    fields.delete(lower).unwrap();
+    assert!(!fields.has(upper));
+    assert!(!fields.has(lower));
+
+    fields.append(lower, b"val1").unwrap();
+    fields.append(upper, b"val2").unwrap();
+    assert_eq!(fields.copy_all(),
+               [(lower.to_string(), b"val1".to_vec()),
+                (lower.to_string(), b"val2".to_vec())]);
+    assert_eq!(fields.get_and_delete(upper).unwrap(),
+               [b"val1".to_vec(), b"val2".to_vec()]);
+
+    fields.append(upper, b"val2").unwrap();
+    fields.append(lower, b"val1").unwrap();
+    // https://github.com/bytecodealliance/wasmtime/issues/11770
+    // assert_eq!(fields.copy_all(),
+    //            [(upper.to_string(), b"val2".to_vec()),
+    //             (upper.to_string(), b"val1".to_vec())]);
+    assert_eq!(fields.get_and_delete(lower).unwrap(),
+               [b"val2".to_vec(), b"val1".to_vec()]);
+}
+
+struct Component;
+export!(Component);
+impl exports::wasi::cli::run::Guest for Component {
+    async fn run() -> Result<(), ()> {
+        test_empty_fields();
+        test_fields_with_foo();
+        test_invalid_field_names();
+        test_valid_field_names();
+        test_invalid_field_values();
+        test_valid_field_values();
+        test_field_name_case_insensitivity();
+        Ok(())
+    }
+}
+
+fn main() {
+    unreachable!("main is a stub");
+}