feat(werkbank): make the loop runnable — enqueue + artifact serve/fetch (WB-05b) (#209)

compliance-agent/src/ingest/blob.rs

@@ -32,6 +32,30 @@ pub fn hash_file(path: &Path) -> Result<(String, u64), AgentError> {
     Ok((hex::encode(hasher.finalize()), total))
 }
 
+/// Store raw bytes in the content-addressed blob store under `base`, returning
+/// the SHA-256 digest. Used to stash a small derived artifact (e.g. the extracted
+/// PLC program source) so a Werkbank runner can fetch it by hash. Idempotent.
+pub fn store_bytes(base: &Path, bytes: &[u8]) -> Result<String, AgentError> {
+    let sha = hex::encode(Sha256::digest(bytes));
+    let dir = base.join("blobs").join(&sha[0..2]);
+    fs::create_dir_all(&dir)?;
+    let dest = dir.join(&sha);
+    if !dest.exists() {
+        fs::write(&dest, bytes)?;
+    }
+    Ok(sha)
+}
+
+/// Read a blob's bytes by its SHA-256 digest. Rejects a non-hex/wrong-length hash
+/// so a request can't traverse outside the blob store.
+pub fn read_blob(base: &Path, sha: &str) -> Result<Vec<u8>, AgentError> {
+    if sha.len() != 64 || !sha.bytes().all(|b| b.is_ascii_hexdigit()) {
+        return Err(AgentError::Other(format!("invalid content hash '{sha}'")));
+    }
+    let path = base.join("blobs").join(&sha[0..2]).join(sha);
+    Ok(fs::read(path)?)
+}
+
 /// Copy `src` into the content-addressed blob store under `base`, returning the
 /// stored path. Idempotent: an already-present blob is not rewritten.
 pub fn store_file(base: &Path, src: &Path, sha: &str) -> Result<PathBuf, AgentError> {