Add native error derive macro

CHANGELOG.md

@@ -6,6 +6,12 @@ All notable changes to this project will be documented in this file.
 ### Added
 - `masterror::error::template` module providing a parsed representation of
   `#[error("...")]` strings and a formatter hook for future custom derives.
+- Internal `masterror-derive` crate powering the native `masterror::Error`
+  derive macro.
+
+### Changed
+- `masterror::Error` now uses the in-tree derive, removing the dependency on
+  `thiserror` while keeping the same runtime behaviour and diagnostics.
 
 ## [0.5.0] - 2025-09-23
 

Cargo.toml

@@ -12,6 +12,12 @@ build = "build.rs"
 categories = ["rust-patterns", "web-programming"]
 keywords = ["error", "api", "framework"]
 
+[workspace]
+members = [
+  "masterror-derive",
+  "masterror-template"
+]
+
 
 [features]
 default = []
@@ -33,7 +39,8 @@ turnkey = []
 openapi = ["dep:utoipa"]
 
 [dependencies]
-thiserror = "2"
+masterror-derive = { path = "masterror-derive" }
+masterror-template = { path = "masterror-template" }
 tracing = "0.1"
 
 serde = { version = "1", features = ["derive"] }

README.md

@@ -52,8 +52,8 @@ masterror = { version = "0.5.0", default-features = false }
 - **Clean wire contract.** `ErrorResponse { status, code, message, details?, retry?, www_authenticate? }`.
 - **One log at boundary.** Log once with `tracing`.
 - **Less boilerplate.** Built-in conversions, compact prelude, and the
-  `masterror::Error` re-export of `thiserror::Error` with `#[from]` /
-  `#[error(transparent)]` support.
+  native `masterror::Error` derive with `#[from]` / `#[error(transparent)]`
+  support.
 - **Consistent workspace.** Same error surface across crates.
 
 </details>
@@ -142,7 +142,7 @@ let wrapped = WrappedDomainError::from(err);
 assert_eq!(wrapped.to_string(), "I/O failed: disk offline");
 ~~~
 
-- `use masterror::Error;` re-exports `thiserror::Error`.
+- `use masterror::Error;` brings the crate's derive macro into scope.
 - `#[from]` automatically implements `From<...>` while ensuring wrapper shapes are
   valid.
 - `#[error(transparent)]` enforces single-field wrappers that forward

README.template.md

@@ -49,8 +49,8 @@ masterror = { version = "{{CRATE_VERSION}}", default-features = false }
 - **Clean wire contract.** `ErrorResponse { status, code, message, details?, retry?, www_authenticate? }`.
 - **One log at boundary.** Log once with `tracing`.
 - **Less boilerplate.** Built-in conversions, compact prelude, and the
-  `masterror::Error` re-export of `thiserror::Error` with `#[from]` /
-  `#[error(transparent)]` support.
+  native `masterror::Error` derive with `#[from]` / `#[error(transparent)]`
+  support.
 - **Consistent workspace.** Same error surface across crates.
 
 </details>
@@ -136,7 +136,7 @@ let wrapped = WrappedDomainError::from(err);
 assert_eq!(wrapped.to_string(), "I/O failed: disk offline");
 ~~~
 
-- `use masterror::Error;` re-exports `thiserror::Error`.
+- `use masterror::Error;` brings the crate's derive macro into scope.
 - `#[from]` automatically implements `From<...>` while ensuring wrapper shapes are
   valid.
 - `#[error(transparent)]` enforces single-field wrappers that forward

masterror-derive/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "masterror-derive"
+version = "0.1.0"
+edition = "2024"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1"
+quote = "1"
+syn = { version = "2", features = ["full", "extra-traits"] }
+masterror-template = { path = "../masterror-template" }