diff --git a/Cargo.lock b/Cargo.lock
index d419227..0d70b9d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -43,7 +43,7 @@ checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
 [[package]]
 name = "chain-module-sdk"
-version = "0.3.0"
+version = "0.2.1"
 dependencies = [
  "chain-module-sdk-macros",
  "serde",
@@ -55,7 +55,7 @@ dependencies = [
 
 [[package]]
 name = "chain-module-sdk-macros"
-version = "0.3.0"
+version = "0.2.1"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/Cargo.toml b/Cargo.toml
index 2101c8c..bb0f709 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,7 +6,7 @@ members = [
 ]
 
 [workspace.package]
-version = "0.3.0"
+version = "0.2.1"
 edition = "2024"
 authors = ["Dr. Stefan Flemming <chain@flemming.ai>"]
 license = "Apache-2.0"
diff --git a/crates/chain-module-sdk-macros/src/lib.rs b/crates/chain-module-sdk-macros/src/lib.rs
index e64e49b..3d0cfb5 100644
--- a/crates/chain-module-sdk-macros/src/lib.rs
+++ b/crates/chain-module-sdk-macros/src/lib.rs
@@ -1,6 +1,7 @@
 //! Procedural macros powering `chain-module-sdk`.
 //!
-//! This crate exists only to host the `#[chain_module]` attribute.
+//! This crate exists only to host the `#[chain_module]` attribute
+//! (and its legacy alias `#[fai_module]`).
 //! Module authors should depend on `chain-module-sdk` (which
 //! re-exports the macro), not on this crate directly.
 
@@ -27,6 +28,18 @@ const WIT_INLINE: &str = include_str!("../../../wit/world.wit");
 /// anything — only its signature matters.
 #[proc_macro_attribute]
 pub fn chain_module(_attrs: TokenStream, input: TokenStream) -> TokenStream {
+    expand_module(input)
+}
+
+/// Legacy alias for [`chain_module`], kept so modules written
+/// before the product rename keep compiling. New code uses
+/// `#[chain_module]`.
+#[proc_macro_attribute]
+pub fn fai_module(_attrs: TokenStream, input: TokenStream) -> TokenStream {
+    expand_module(input)
+}
+
+fn expand_module(input: TokenStream) -> TokenStream {
     let user_fn = parse_macro_input!(input as ItemFn);
     let user_fn_name = user_fn.sig.ident.clone();
     let wit_literal = WIT_INLINE;
diff --git a/crates/chain-module-sdk/src/context.rs b/crates/chain-module-sdk/src/context.rs
index f16a3f5..32080d0 100644
--- a/crates/chain-module-sdk/src/context.rs
+++ b/crates/chain-module-sdk/src/context.rs
@@ -1,7 +1,7 @@
 //! Invocation context passed to a module on every call.
 //!
 //! Mirrors the WIT `invocation-context` record. The
-//! `#[chain_module]` macro builds this from the WIT-generated value
+//! `#[fai_module]` macro builds this from the WIT-generated value
 //! before handing it to user code.
 
 #[derive(Debug, Clone, PartialEq, Eq)]
diff --git a/crates/chain-module-sdk/src/host.rs b/crates/chain-module-sdk/src/host.rs
index e73579d..de9572d 100644
--- a/crates/chain-module-sdk/src/host.rs
+++ b/crates/chain-module-sdk/src/host.rs
@@ -1,7 +1,7 @@
 //! Host-callback plumbing for `Context::emit` (WIT 1.1 `emit-event`).
 //!
 //! The WIT host imports (`emit-event`) are only reachable from the
-//! `wit_bindgen`-generated glue inside the `#[chain_module]` expansion,
+//! `wit_bindgen`-generated glue inside the `#[fai_module]` expansion,
 //! which lives in the module crate — not here. So the macro installs a
 //! function pointer that reaches the real host import, and
 //! [`Context::emit`](crate::Context::emit) calls it through this hook.
@@ -18,7 +18,7 @@ thread_local! {
     static EMIT_HOOK: Cell<Option<fn(&str, Payload)>> = const { Cell::new(None) };
 }
 
-/// Install the emit hook. Called by the `#[chain_module]` expansion at
+/// Install the emit hook. Called by the `#[fai_module]` expansion at
 /// the start of each invocation. Not part of the stable public API.
 #[doc(hidden)]
 pub fn __set_emit_hook(f: fn(&str, Payload)) {
diff --git a/crates/chain-module-sdk/src/inputs.rs b/crates/chain-module-sdk/src/inputs.rs
index ea1cc54..9f8b46e 100644
--- a/crates/chain-module-sdk/src/inputs.rs
+++ b/crates/chain-module-sdk/src/inputs.rs
@@ -19,7 +19,7 @@ pub struct Inputs {
 
 impl Inputs {
     /// Build directly from a list of `(name, payload)` pairs.
-    /// Used by the `#[chain_module]` macro after WIT conversion.
+    /// Used by the `#[fai_module]` macro after WIT conversion.
     #[doc(hidden)]
     pub fn __from_pairs(items: Vec<(String, Payload)>) -> Self {
         Self { items }
diff --git a/crates/chain-module-sdk/src/lib.rs b/crates/chain-module-sdk/src/lib.rs
index d059f63..c103536 100644
--- a/crates/chain-module-sdk/src/lib.rs
+++ b/crates/chain-module-sdk/src/lib.rs
@@ -36,7 +36,7 @@ pub use inputs::Inputs;
 pub use outputs::Outputs;
 pub use payload::{BytesValue, FileRef, Payload};
 
-pub use chain_module_sdk_macros::chain_module;
+pub use chain_module_sdk_macros::{chain_module, fai_module};
 
 // Emit-hook plumbing used by the `#[chain_module]` expansion (wasm32)
 // so `Context::emit` reaches the WIT `emit-event` host import.
@@ -49,6 +49,7 @@ pub(crate) use host::emit;
 pub mod prelude {
     pub use super::{
         BytesValue, Context, FileRef, Inputs, ModuleError, Outputs, Payload, chain_module,
+        fai_module,
     };
 }
 
diff --git a/crates/chain-module-sdk/src/outputs.rs b/crates/chain-module-sdk/src/outputs.rs
index 037f350..3ac21d8 100644
--- a/crates/chain-module-sdk/src/outputs.rs
+++ b/crates/chain-module-sdk/src/outputs.rs
@@ -71,7 +71,7 @@ impl Outputs {
     }
 
     /// Consume the builder into the underlying `(name, payload)` list.
-    /// Used by the `#[chain_module]` macro after WIT conversion.
+    /// Used by the `#[fai_module]` macro after WIT conversion.
     #[doc(hidden)]
     pub fn __into_pairs(self) -> Vec<(String, Payload)> {
         self.items
diff --git a/crates/chain-module-sdk/src/payload.rs b/crates/chain-module-sdk/src/payload.rs
index 8016bf0..4a87c2e 100644
--- a/crates/chain-module-sdk/src/payload.rs
+++ b/crates/chain-module-sdk/src/payload.rs
@@ -2,7 +2,7 @@
 //!
 //! The shape is fixed by the v1.0 WIT freeze. Field-by-field
 //! conversion to and from the WIT-generated type happens inside
-//! the `#[chain_module]` macro expansion in the user crate.
+//! the `#[fai_module]` macro expansion in the user crate.
 
 use serde::{Deserialize, Serialize};
 
diff --git a/examples/echo/Cargo.lock b/examples/echo/Cargo.lock
index a7b3f0a..8b91627 100644
--- a/examples/echo/Cargo.lock
+++ b/examples/echo/Cargo.lock
@@ -34,7 +34,7 @@ checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
 [[package]]
 name = "chain-module-sdk"
-version = "0.2.1"
+version = "0.2.0"
 dependencies = [
  "chain-module-sdk-macros",
  "serde",
@@ -45,7 +45,7 @@ dependencies = [
 
 [[package]]
 name = "chain-module-sdk-macros"
-version = "0.2.1"
+version = "0.2.0"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/examples/echo/Cargo.toml b/examples/echo/Cargo.toml
index 7ec5300..da76171 100644
--- a/examples/echo/Cargo.toml
+++ b/examples/echo/Cargo.toml
@@ -10,7 +10,7 @@ version = "0.1.0"
 edition = "2024"
 license = "Apache-2.0"
 publish = false
-description = "Reference module showing the minimum needed to write a Ch∆In module with chain-module-sdk."
+description = "Reference module showing the minimum needed to write an F∆I module with chain-module-sdk."
 
 [lib]
 crate-type = ["cdylib"]
diff --git a/examples/echo/src/lib.rs b/examples/echo/src/lib.rs
index e538232..4d2a55b 100644
--- a/examples/echo/src/lib.rs
+++ b/examples/echo/src/lib.rs
@@ -1,4 +1,4 @@
-//! Minimum-viable Ch∆In module — echoes the first text input.
+//! Minimum-viable F∆I module — echoes the first text input.
 //!
 //! Demonstrates the entire authoring surface: a single function
 //! decorated with `#[chain_module]`. No `wit_bindgen`, no
diff --git a/examples/progress/Cargo.lock b/examples/progress/Cargo.lock
index 19c18a7..ff92268 100644
--- a/examples/progress/Cargo.lock
+++ b/examples/progress/Cargo.lock
@@ -34,7 +34,7 @@ checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
 [[package]]
 name = "chain-module-sdk"
-version = "0.3.0"
+version = "0.2.0"
 dependencies = [
  "chain-module-sdk-macros",
  "serde",
@@ -45,7 +45,7 @@ dependencies = [
 
 [[package]]
 name = "chain-module-sdk-macros"
-version = "0.3.0"
+version = "0.2.0"
 dependencies = [
  "proc-macro2",
  "quote",