Have viceroy --adapt add producer metadata to wasm binary.

CHANGELOG.md

@@ -4,6 +4,7 @@
 - Add support for "library" components which don't export `http_incoming`.
 - Add non-shift adapter when user module is using wit-bindgen.
 - Update to Wasmtime 39 ([#584](https://github.com/fastly/Viceroy/pull/584))
+- Make "viceroy adapt" add "produced-by" metadata to its output. ([#586](https://github.com/fastly/Viceroy/pull/586))
 
 ## 0.16.4 (2026-01-26)
 

Cargo.toml

@@ -59,6 +59,8 @@ tracing-futures = { workspace = true }
 url = { workspace = true }
 wasmparser = { workspace = true }
 wasm-encoder = { workspace = true }
+# Disable the "serde" feature which we don't need.
+wasm-metadata = { version = "0.244.0", default-features = false }
 wit-component = { workspace = true }
 wasmtime = { workspace = true }
 wasmtime-wasi = { workspace = true }

src/adapt.rs

@@ -1,3 +1,5 @@
+use anyhow::Context;
+
 /// The full adapter.
 const ADAPTER_BYTES: &[u8] = include_bytes!("../wasm_abi/data/viceroy-component-adapter.wasm");
 const ADAPTER_NOSHIFT_BYTES: &[u8] =
@@ -56,6 +58,24 @@ pub fn adapt_bytes(bytes: &[u8]) -> anyhow::Result<Vec<u8>> {
         .validate(true)
         .encode()?;
 
+    // Add "viceroy" to the producers section.
+    let mut producers = wasm_metadata::Producers::empty();
+    let mut flags = Vec::with_capacity(2);
+    if library {
+        flags.push("library");
+    }
+    if needs_no_shift_adapter {
+        flags.push("noshift");
+    }
+    producers.add(
+        "processed-by",
+        "viceroy adapt",
+        &format!("{} ({})", env!("CARGO_PKG_VERSION"), flags.join(", ")),
+    );
+    let component = producers
+        .add_to_wasm(&component)
+        .context("failed to add viceroy producer metadata to wasm")?;
+
     Ok(component)
 }