fix: serve original PDF uploads (passthrough) and persist artifacts on disk

.gitignore

@@ -8,6 +8,9 @@ target/
 *.log
 /evidence/
 
+# Local artifact store data (clearfolio.artifact-store.root-dir default)
+/data/
+
 # Local agent/tool artifacts
 tmp/
 registered_agents.json

ARCHITECTURE.md

@@ -24,16 +24,21 @@ Current state: viewer/state API is implemented in this repository; downstream S2
   - `GET /artifacts/{docId}.pdf`: serves PDF bytes for SUCCEEDED jobs with basic HTTP Range support.
 - `DefaultDocumentConversionService` (`src/main/java/com/clearfolio/viewer/service/DefaultDocumentConversionService.java`)
   - Validation, content hash generation, dedupe lookup, repository persistence, worker enqueue.
+  - PDF passthrough: uploads that declare PDF (extension/content type) and carry the `%PDF-` magic header are seeded into the artifact store as-is, so the original bytes are served instead of a generated placeholder.
 - `DefaultDocumentValidationService` (`src/main/java/com/clearfolio/viewer/service/DefaultDocumentValidationService.java`)
   - Enforces extension blocklist and size limits, including auditable policy-override exception lane.
 - `DefaultConversionWorker` (`src/main/java/com/clearfolio/viewer/service/DefaultConversionWorker.java`)
   - Runs conversion on a bounded executor with retry scheduling and dead-letter fallback.
 - `ArtifactStore` (`src/main/java/com/clearfolio/viewer/artifact/ArtifactStore.java`)
   - Stores converted PDF bytes by docId.
+- `FileSystemArtifactStore` (`src/main/java/com/clearfolio/viewer/artifact/FileSystemArtifactStore.java`)
+  - Default disk-backed artifact store; persists bytes plus minimal metadata under `clearfolio.artifact-store.root-dir` (default `data/artifacts`) so artifacts survive restarts, with an in-memory cache on the read path.
 - `InMemoryArtifactStore` (`src/main/java/com/clearfolio/viewer/artifact/InMemoryArtifactStore.java`)
-  - In-memory artifact store implementation.
+  - In-memory artifact store implementation used by tests and `clearfolio.artifact-store.mode=in-memory`.
+- `ArtifactStoreConfig` (`src/main/java/com/clearfolio/viewer/config/ArtifactStoreConfig.java`)
+  - Selects the artifact store implementation from `ArtifactStoreProperties`.
 - `PdfBoxArtifactGenerator` (`src/main/java/com/clearfolio/viewer/artifact/PdfBoxArtifactGenerator.java`)
-  - Generates a simple one-page PDF via PDFBox for the default conversion path.
+  - Generates a placeholder one-page PDF via PDFBox for non-PDF sources; real docx/hwp conversion remains future work.
 - `InMemoryConversionJobRepository` (`src/main/java/com/clearfolio/viewer/repository/InMemoryConversionJobRepository.java`)
   - In-memory job store and content-hash dedupe index.
 - `ConversionJob` (`src/main/java/com/clearfolio/viewer/model/ConversionJob.java`)

LICENSE

@@ -0,0 +1,202 @@
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src/main/java/com/clearfolio/viewer/artifact/ArtifactStore.java

@@ -6,8 +6,9 @@
 /**
  * Stores and retrieves preview artifacts produced by conversion jobs.
  *
- * <p>This MVP abstraction intentionally keeps operations in-memory and CPU-only
- * so request paths remain non-blocking (no filesystem/network I/O).
+ * <p>Implementations keep the hot request path CPU-only where possible; the
+ * disk-backed implementation caches bytes in memory after the first access so
+ * filesystem reads are limited to cache misses (for example, after a restart).
  */
 public interface ArtifactStore {
 

src/main/java/com/clearfolio/viewer/artifact/FileSystemArtifactStore.java

@@ -0,0 +1,131 @@
+package com.clearfolio.viewer.artifact;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.time.Instant;
+import java.util.Optional;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Disk-backed {@link ArtifactStore} that persists artifact bytes and minimal
+ * metadata under a configurable root directory so artifacts survive process
+ * restarts.
+ *
+ * <p>Artifact bytes are cached in memory after the first write or read, so the
+ * request-serving path only touches the filesystem when an artifact is not yet
+ * cached (for example, on the first read after a restart).
+ */
+public final class FileSystemArtifactStore implements ArtifactStore {
+
+    @FunctionalInterface
+    interface BytesWriter {
+        void write(Path path, byte[] bytes) throws IOException;
+    }
+
+    @FunctionalInterface
+    interface BytesReader {
+        byte[] read(Path path) throws IOException;
+    }
+
+    private static final String PDF_SUFFIX = ".pdf";
+    private static final String METADATA_SUFFIX = ".meta.properties";
+
+    private final Path rootDir;
+    private final BytesWriter bytesWriter;
+    private final BytesReader bytesReader;
+    private final ConcurrentHashMap<UUID, byte[]> cache = new ConcurrentHashMap<>();
+
+    /**
+     * Creates a store rooted at the supplied directory, creating it when absent.
+     *
+     * @param rootDir directory that holds artifact bytes and metadata files
+     */
+    public FileSystemArtifactStore(Path rootDir) {
+        this(rootDir, (path, bytes) -> Files.write(path, bytes), Files::readAllBytes);
+    }
+
+    FileSystemArtifactStore(Path rootDir, BytesWriter bytesWriter, BytesReader bytesReader) {
+        this.rootDir = rootDir;
+        this.bytesWriter = bytesWriter;
+        this.bytesReader = bytesReader;
+        try {
+            Files.createDirectories(rootDir);
+        } catch (IOException ex) {
+            throw new IllegalStateException("failed to create artifact storage directory: " + rootDir, ex);
+        }
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void putPdf(UUID docId, byte[] pdfBytes) {
+        byte[] copy = pdfBytes.clone();
+        try {
+            bytesWriter.write(pdfPath(docId), copy);
+            bytesWriter.write(metadataPath(docId), metadataBytes(docId, copy));
+        } catch (IOException ex) {
+            throw new IllegalStateException("failed to persist artifact for docId " + docId, ex);
+        }
+        cache.put(docId, copy);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public Optional<byte[]> getPdf(UUID docId) {
+        byte[] cached = cache.get(docId);
+        if (cached != null) {
+            return Optional.of(cached.clone());
+        }
+
+        Path pdfPath = pdfPath(docId);
+        if (!Files.exists(pdfPath)) {
+            return Optional.empty();
+        }
+
+        try {
+            byte[] loaded = bytesReader.read(pdfPath);
+            cache.put(docId, loaded);
+            return Optional.of(loaded.clone());
+        } catch (IOException ex) {
+            throw new IllegalStateException("failed to read artifact for docId " + docId, ex);
+        }
+    }
+
+    private Path pdfPath(UUID docId) {
+        return rootDir.resolve(docId + PDF_SUFFIX);
+    }
+
+    private Path metadataPath(UUID docId) {
+        return rootDir.resolve(docId + METADATA_SUFFIX);
+    }
+
+    private static byte[] metadataBytes(UUID docId, byte[] pdfBytes) {
+        String metadata = "docId=" + docId + "\n"
+                + "sizeBytes=" + pdfBytes.length + "\n"
+                + "sha256=" + sha256Hex(pdfBytes) + "\n"
+                + "storedAt=" + Instant.now() + "\n";
+        return metadata.getBytes(StandardCharsets.UTF_8);
+    }
+
+    private static String sha256Hex(byte[] bytes) {
+        try {
+            MessageDigest digest = MessageDigest.getInstance("SHA-256");
+            byte[] raw = digest.digest(bytes);
+            StringBuilder hex = new StringBuilder(raw.length * 2);
+            for (byte b : raw) {
+                hex.append(String.format("%02x", b));
+            }
+            return hex.toString();
+        } catch (NoSuchAlgorithmException ex) {
+            throw new IllegalStateException("SHA-256 digest unavailable", ex);
+        }
+    }
+}

src/main/java/com/clearfolio/viewer/artifact/InMemoryArtifactStore.java

@@ -4,12 +4,13 @@
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 
-import org.springframework.stereotype.Component;
-
 /**
  * In-memory implementation of {@link ArtifactStore}.
+ *
+ * <p>Contents do not survive restarts; this implementation backs tests and the
+ * {@code clearfolio.artifact-store.mode=in-memory} configuration, while the
+ * disk-backed {@link FileSystemArtifactStore} is the runtime default.
  */
-@Component
 public class InMemoryArtifactStore implements ArtifactStore {
 
     private final ConcurrentHashMap<UUID, byte[]> pdfByDocId = new ConcurrentHashMap<>();