Reject unsupported aws-chunked uploads

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

.env.example

@@ -1,6 +1,7 @@
 LOG_LEVEL=debug
 LOG_FORMAT=text
 DATA_PATH=data/
+FS_MAX_OBJECT_UPLOAD_BYTES=5368709120
 PORT=2600
 AUDIT_LOG=true
 ADDRESS=0.0.0.0

.github/workflows/ci.yml

@@ -0,0 +1,24 @@
+name: CI
+
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+
+      - name: Run tests
+        run: |
+          export GOCACHE=/tmp/go-build-cache
+          go test ./...
+

.github/workflows/release-image.yml

@@ -0,0 +1,66 @@
+name: Release Image
+
+on:
+  push:
+    tags:
+      - "v*.*.*"
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set build date
+        id: date
+        run: echo "value=$(date -u +%Y-%m-%dT%H:%M:%SZ)" >> "$GITHUB_OUTPUT"
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Docker metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/${{ github.repository }}
+          tags: |
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+            type=sha
+          labels: |
+            org.opencontainers.image.title=fs
+            org.opencontainers.image.description=Lightweight S3-compatible object storage
+            org.opencontainers.image.source=https://github.com/${{ github.repository }}
+            org.opencontainers.image.revision=${{ github.sha }}
+            org.opencontainers.image.created=${{ steps.date.outputs.value }}
+
+      - name: Build and push image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          build-args: |
+            VERSION=${{ github.ref_name }}
+            COMMIT=${{ github.sha }}
+            DATE=${{ steps.date.outputs.value }}
+

Dockerfile

@@ -6,7 +6,13 @@ COPY go.mod go.sum ./
 RUN go mod download
 
 COPY . .
-RUN CGO_ENABLED=0 GOOS=linux go build -o /app/fs .
+ARG VERSION=dev
+ARG COMMIT=none
+ARG DATE=unknown
+RUN CGO_ENABLED=0 GOOS=linux go build \
+  -trimpath \
+  -ldflags "-s -w -X main.version=${VERSION} -X main.commit=${COMMIT} -X main.date=${DATE}" \
+  -o /app/fs .
 
 FROM alpine:3.23 AS runner
 

README.md

@@ -49,6 +49,61 @@ Admin API (JSON):
 - `PUT /_admin/v1/users/{accessKeyId}/status`
 - `DELETE /_admin/v1/users/{accessKeyId}`
 
+Admin API policy examples (SigV4):
+```bash
+ENDPOINT="http://localhost:2600"
+REGION="us-east-1"
+ADMIN_ACCESS_KEY="${FS_ROOT_USER}"
+ADMIN_SECRET_KEY="${FS_ROOT_PASSWORD}"
+SIGV4="aws:amz:${REGION}:s3"
+```
+
+Replace user policy with one scoped statement:
+```bash
+curl --aws-sigv4 "$SIGV4" \
+  --user "${ADMIN_ACCESS_KEY}:${ADMIN_SECRET_KEY}" \
+  -H "Content-Type: application/json" \
+  -X PUT "${ENDPOINT}/_admin/v1/users/test-user/policy" \
+  -d '{
+    "policy": {
+      "statements": [
+        {
+          "effect": "allow",
+          "actions": ["s3:ListBucket", "s3:GetObject", "s3:PutObject", "s3:DeleteObject"],
+          "bucket": "backup",
+          "prefix": "restic/*"
+        }
+      ]
+    }
+  }'
+```
+
+Set multiple statements (for multiple buckets):
+```bash
+curl --aws-sigv4 "$SIGV4" \
+  --user "${ADMIN_ACCESS_KEY}:${ADMIN_SECRET_KEY}" \
+  -H "Content-Type: application/json" \
+  -X PUT "${ENDPOINT}/_admin/v1/users/test-user/policy" \
+  -d '{
+    "policy": {
+      "statements": [
+        {
+          "effect": "allow",
+          "actions": ["s3:ListBucket", "s3:GetObject"],
+          "bucket": "test-bucket",
+          "prefix": "*"
+        },
+        {
+          "effect": "allow",
+          "actions": ["s3:ListBucket", "s3:GetObject", "s3:PutObject", "s3:DeleteObject"],
+          "bucket": "test-bucket-2",
+          "prefix": "*"
+        }
+      ]
+    }
+  }'
+```
+
 Admin CLI:
 - `fs admin user create --access-key backup-user --role readwrite`
 - `fs admin user list`
@@ -56,8 +111,12 @@ Admin CLI:
 - `fs admin user set-status backup-user --status disabled`
 - `fs admin user set-role backup-user --role readonly --bucket backup-bucket --prefix restic/`
 - `fs admin user set-role backup-user --role readwrite --bucket backups-2` (appends another statement)
+- `fs admin user remove-role backup-user --role readonly --bucket backup-bucket --prefix restic/`
 - `fs admin user set-role backup-user --role admin --replace` (replaces all statements)
 - `fs admin user delete backup-user`
+- `fs admin snapshot create --data-path /var/lib/fs --out /backup/fs-20260311.tar.gz`
+- `fs admin snapshot inspect --file /backup/fs-20260311.tar.gz`
+- `fs admin snapshot restore --file /backup/fs-20260311.tar.gz --data-path /var/lib/fs --force`
 - `fs admin diag health`
 - `fs admin diag version`
 
@@ -68,6 +127,9 @@ Required when `FS_AUTH_ENABLED=true`:
 - `FS_ROOT_USER` and `FS_ROOT_PASSWORD` define initial credentials
 - `ADMIN_API_ENABLED=true` enables `/_admin/v1/*` routes (bootstrap key only)
 
+Upload limits:
+- `FS_MAX_OBJECT_UPLOAD_BYTES` limits object PUT payloads, multipart upload parts, and completed multipart object size (default 5 GiB).
+
 Reference: `auth/README.md`
 
 Additional docs:
@@ -80,9 +142,12 @@ CLI credential/env resolution for `fs admin`:
   - `FS_ROOT_USER` / `FS_ROOT_PASSWORD` (same defaults as server bootstrap)
   - `FSCLI_ACCESS_KEY` / `FSCLI_SECRET_KEY`
   - `AWS_ACCESS_KEY_ID` / `AWS_SECRET_ACCESS_KEY`
-  - `FSCLI_ENDPOINT` (fallback to `ADDRESS` + `PORT`, then `http://localhost:3000`)
+  - `FSCLI_ENDPOINT` (fallback to `ADDRESS` + `PORT`, then `http://localhost:2600`)
   - `FSCLI_REGION` (fallback `FS_AUTH_REGION`, default `us-east-1`)
 
+Note:
+- `fs admin snapshot ...` commands operate locally on filesystem paths and do not require endpoint or auth credentials.
+
 Health:
 - `GET /healthz`
 - `HEAD /healthz`

api/api.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"bufio"
+	"bytes"
 	"context"
 	"encoding/base64"
 	"encoding/xml"
@@ -40,6 +41,7 @@ const (
 	maxXMLBodyBytes         int64 = 1 << 20
 	maxDeleteObjects              = 1000
 	maxObjectKeyBytes             = 1024
+	maxAWSChunkedLineBytes        = 8 << 10
 	serverReadHeaderTimeout       = 5 * time.Second
 	serverReadTimeout             = 60 * time.Second
 	serverWriteTimeout            = 120 * time.Second
@@ -138,11 +140,87 @@ func validateObjectKey(key string) *s3APIError {
 	return nil
 }
 
+func objectKeyFromRequest(r *http.Request) (string, *s3APIError) {
+	rawKey := rawObjectKeyFromRequest(r)
+	key, err := normalizeObjectKey(rawKey)
+	if err != nil {
+		apiErr := s3ErrInvalidArgument
+		return "", &apiErr
+	}
+	if apiErr := validateObjectKey(key); apiErr != nil {
+		return "", apiErr
+	}
+	return key, nil
+}
+
+func rawObjectKeyFromRequest(r *http.Request) string {
+	if r == nil || r.URL == nil {
+		return ""
+	}
+	bucket := chi.URLParam(r, "bucket")
+	if bucket == "" {
+		return chi.URLParam(r, "*")
+	}
+	escapedPath := r.URL.EscapedPath()
+	prefix := "/" + bucket + "/"
+	if strings.HasPrefix(escapedPath, prefix) {
+		return strings.TrimPrefix(escapedPath, prefix)
+	}
+	return chi.URLParam(r, "*")
+}
+
+func normalizeObjectKey(raw string) (string, error) {
+	if raw == "" {
+		return "", nil
+	}
+	return url.PathUnescape(raw)
+}
+
+func parseCopySource(raw string) (string, string, error) {
+	raw = strings.TrimSpace(raw)
+	raw = strings.TrimPrefix(raw, "/")
+	if idx := strings.IndexByte(raw, '?'); idx >= 0 {
+		raw = raw[:idx]
+	}
+	bucket, rawKey, found := strings.Cut(raw, "/")
+	if !found || strings.TrimSpace(bucket) == "" || rawKey == "" {
+		return "", "", errors.New("invalid copy source")
+	}
+	key, err := normalizeObjectKey(rawKey)
+	if err != nil {
+		return "", "", err
+	}
+	if apiErr := validateObjectKey(key); apiErr != nil {
+		return "", "", errors.New(apiErr.Code)
+	}
+	return bucket, key, nil
+}
+
+func (h *Handler) authorizeCopySource(r *http.Request, bucket, key string) error {
+	return h.authorizeObjectAction(r, auth.ActionGetObject, bucket, key)
+}
+
+func (h *Handler) authorizeObjectAction(r *http.Request, action auth.Action, bucket, key string) error {
+	if h.authSvc == nil || !h.authSvc.Config().Enabled {
+		return nil
+	}
+
+	authCtx, ok := auth.GetRequestContext(r.Context())
+	if !ok || !authCtx.Authenticated {
+		return auth.ErrAccessDenied
+	}
+
+	return h.authSvc.Authorize(authCtx.AccessKeyID, auth.RequestTarget{
+		Action: action,
+		Bucket: bucket,
+		Key:    key,
+	})
+}
+
 func (h *Handler) handleGetObject(w http.ResponseWriter, r *http.Request) {
 	bucket := chi.URLParam(r, "bucket")
-	key := chi.URLParam(r, "*")
-
-	if apiErr := validateObjectKey(key); apiErr != nil {
+	key, apiErr := objectKeyFromRequest(r)
+	if apiErr != nil {
 		writeS3Error(w, r, *apiErr, r.URL.Path)
 		return
 	}
@@ -199,8 +277,8 @@ func (h *Handler) handleGetObject(w http.ResponseWriter, r *http.Request) {
 
 func (h *Handler) handlePostObject(w http.ResponseWriter, r *http.Request) {
 	bucket := chi.URLParam(r, "bucket")
-	key := chi.URLParam(r, "*")
-	if apiErr := validateObjectKey(key); apiErr != nil {
+	key, apiErr := objectKeyFromRequest(r)
+	if apiErr != nil {
 		writeS3Error(w, r, *apiErr, r.URL.Path)
 		return
 	}
@@ -234,6 +312,10 @@ func (h *Handler) handlePostObject(w http.ResponseWriter, r *http.Request) {
 		r.Body = http.MaxBytesReader(w, r.Body, maxXMLBodyBytes)
 		var req models.CompleteMultipartUploadRequest
 		if err := xml.NewDecoder(r.Body).Decode(&req); err != nil {
+			if errors.Is(err, auth.ErrSignatureDoesNotMatch) {
+				writeMappedS3Error(w, r, err)
+				return
+			}
 			var maxErr *http.MaxBytesError
 			if errors.As(err, &maxErr) {
 				writeS3Error(w, r, s3ErrEntityTooLarge, r.URL.Path)
@@ -275,8 +357,8 @@ func (h *Handler) handlePostObject(w http.ResponseWriter, r *http.Request) {
 
 func (h *Handler) handlePutObject(w http.ResponseWriter, r *http.Request) {
 	bucket := chi.URLParam(r, "bucket")
-	key := chi.URLParam(r, "*")
-	if apiErr := validateObjectKey(key); apiErr != nil {
+	key, apiErr := objectKeyFromRequest(r)
+	if apiErr != nil {
 		writeS3Error(w, r, *apiErr, r.URL.Path)
 		return
 	}
@@ -289,6 +371,10 @@ func (h *Handler) handlePutObject(w http.ResponseWriter, r *http.Request) {
 			writeS3Error(w, r, s3ErrInvalidPart, r.URL.Path)
 			return
 		}
+		if strings.TrimSpace(r.Header.Get("x-amz-copy-source")) != "" {
+			writeS3Error(w, r, s3ErrNotImplemented, r.URL.Path)
+			return
+		}
 
 		partNumber, err := strconv.Atoi(partNumberRaw)
 		if err != nil {
@@ -302,6 +388,10 @@ func (h *Handler) handlePutObject(w http.ResponseWriter, r *http.Request) {
 
 		bodyReader := io.Reader(r.Body)
 		var decodeStream io.ReadCloser
+		if hasUnsupportedAWSChunkedPayload(r) {
+			writeS3Error(w, r, s3ErrInvalidArgument, r.URL.Path)
+			return
+		}
 		if shouldDecodeAWSChunkedPayload(r) {
 			decodeStream = newAWSChunkedDecodingReader(r.Body)
 			defer decodeStream.Close()
@@ -333,6 +423,42 @@ func (h *Handler) handlePutObject(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
+	if copySourceRaw := strings.TrimSpace(r.Header.Get("x-amz-copy-source")); copySourceRaw != "" {
+		srcBucket, srcKey, err := parseCopySource(copySourceRaw)
+		if err != nil {
+			writeS3Error(w, r, s3ErrInvalidArgument, r.URL.Path)
+			return
+		}
+		if err := h.authorizeCopySource(r, srcBucket, srcKey); err != nil {
+			writeMappedS3Error(w, r, err)
+			return
+		}
+
+		manifest, err := h.svc.CopyObject(srcBucket, srcKey, bucket, key)
+		if err != nil {
+			writeMappedS3Error(w, r, err)
+			return
+		}
+
+		response := models.CopyObjectResult{
+			Xmlns:        "http://s3.amazonaws.com/doc/2006-03-01/",
+			LastModified: time.Unix(manifest.CreatedAt, 0).UTC().Format("2006-01-02T15:04:05.000Z"),
+			ETag:         `"` + manifest.ETag + `"`,
+		}
+		payload, err := xml.MarshalIndent(response, "", "    ")
+		if err != nil {
+			writeMappedS3Error(w, r, err)
+			return
+		}
+
+		w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+		w.Header().Set("ETag", `"`+manifest.ETag+`"`)
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte(xml.Header))
+		_, _ = w.Write(payload)
+		return
+	}
+
 	contentType := r.Header.Get("Content-Type")
 	if contentType == "" {
 		contentType = "application/octet-stream"
@@ -340,6 +466,10 @@ func (h *Handler) handlePutObject(w http.ResponseWriter, r *http.Request) {
 
 	bodyReader := io.Reader(r.Body)
 	var decodeStream io.ReadCloser
+	if hasUnsupportedAWSChunkedPayload(r) {
+		writeS3Error(w, r, s3ErrInvalidArgument, r.URL.Path)
+		return
+	}
 	if shouldDecodeAWSChunkedPayload(r) {
 		decodeStream = newAWSChunkedDecodingReader(r.Body)
 		defer decodeStream.Close()
@@ -395,18 +525,27 @@ func (h *Handler) handleListMultipartParts(w http.ResponseWriter, r *http.Reques
 }
 
 func shouldDecodeAWSChunkedPayload(r *http.Request) bool {
-	contentEncoding := strings.ToLower(r.Header.Get("Content-Encoding"))
-	if strings.Contains(contentEncoding, "aws-chunked") {
-		return true
-	}
 	signingMode := strings.ToLower(r.Header.Get("x-amz-content-sha256"))
-	return strings.HasPrefix(signingMode, "streaming-aws4-hmac-sha256-payload")
+	return strings.HasPrefix(signingMode, "streaming-unsigned-payload")
+}
+
+func hasUnsupportedAWSChunkedPayload(r *http.Request) bool {
+	contentEncoding := strings.ToLower(r.Header.Get("Content-Encoding"))
+	if !strings.Contains(contentEncoding, "aws-chunked") {
+		return false
+	}
+	return !shouldDecodeAWSChunkedPayload(r)
 }
 
 func newAWSChunkedDecodingReader(src io.Reader) io.ReadCloser {
+	probedReader, isAWSChunked := probeAWSChunkedPayload(src)
+	if !isAWSChunked {
+		return io.NopCloser(probedReader)
+	}
+
 	pr, pw := io.Pipe()
 	go func() {
-		if err := decodeAWSChunkedPayload(src, pw); err != nil {
+		if err := decodeAWSChunkedPayload(probedReader, pw); err != nil {
 			_ = pw.CloseWithError(err)
 			return
 		}
@@ -415,10 +554,37 @@ func newAWSChunkedDecodingReader(src io.Reader) io.ReadCloser {
 	return pr
 }
 
+func probeAWSChunkedPayload(src io.Reader) (io.Reader, bool) {
+	reader := bufio.NewReaderSize(src, maxAWSChunkedLineBytes)
+	headerLine, err := reader.ReadSlice('\n')
+	replay := io.MultiReader(bytes.NewReader(headerLine), reader)
+	if errors.Is(err, bufio.ErrBufferFull) {
+		return replay, true
+	}
+	if err != nil {
+		return replay, false
+	}
+
+	line := strings.TrimRight(string(headerLine), "\r\n")
+	chunkSizeToken := line
+	if idx := strings.IndexByte(chunkSizeToken, ';'); idx >= 0 {
+		chunkSizeToken = chunkSizeToken[:idx]
+	}
+	chunkSizeToken = strings.TrimSpace(chunkSizeToken)
+	if chunkSizeToken == "" {
+		return replay, false
+	}
+	size, parseErr := strconv.ParseInt(chunkSizeToken, 16, 64)
+	if parseErr != nil || size < 0 {
+		return replay, false
+	}
+	return replay, true
+}
+
 func decodeAWSChunkedPayload(src io.Reader, dst io.Writer) error {
-	reader := bufio.NewReader(src)
+	reader := bufio.NewReaderSize(src, maxAWSChunkedLineBytes)
 	for {
-		headerLine, err := reader.ReadString('\n')
+		headerLine, err := readAWSChunkedLine(reader)
 		if err != nil {
 			return err
 		}
@@ -435,6 +601,17 @@ func decodeAWSChunkedPayload(src io.Reader, dst io.Writer) error {
 		if chunkSize < 0 {
 			return fmt.Errorf("invalid aws-chunked size: %d", chunkSize)
 		}
+		if chunkSize == 0 {
+			for {
+				line, err := readAWSChunkedLine(reader)
+				if err != nil {
+					return err
+				}
+				if line == "\r\n" || line == "\n" {
+					return nil
+				}
+			}
+		}
 		if chunkSize > 0 {
 			if _, err := io.CopyN(dst, reader, chunkSize); err != nil {
 				return err
@@ -448,19 +625,18 @@ func decodeAWSChunkedPayload(src io.Reader, dst io.Writer) error {
 		if crlf[0] != '\r' || crlf[1] != '\n' {
 			return errors.New("invalid aws-chunked payload terminator")
 		}
+	}
+}
 
-		if chunkSize == 0 {
-			for {
-				line, err := reader.ReadString('\n')
-				if err != nil {
-					return err
-				}
-				if line == "\r\n" || line == "\n" {
-					return nil
-				}
-			}
+func readAWSChunkedLine(reader *bufio.Reader) (string, error) {
+	line, err := reader.ReadSlice('\n')
+	if errors.Is(err, bufio.ErrBufferFull) {
+		return "", service.ErrEntityTooLarge
 	}
+	if len(line) > maxAWSChunkedLineBytes {
+		return "", service.ErrEntityTooLarge
 	}
+	return string(line), err
 }
 
 func ifNoneMatchPreconditionFailed(headerValue, etag string) bool {
@@ -488,7 +664,7 @@ func (h *Handler) handlePutBucket(w http.ResponseWriter, r *http.Request) {
 		writeMappedS3Error(w, r, err)
 		return
 	}
-	w.WriteHeader(http.StatusCreated)
+	w.WriteHeader(http.StatusOK)
 }
 
 func (h *Handler) handleDeleteBucket(w http.ResponseWriter, r *http.Request) {
@@ -519,6 +695,10 @@ func (h *Handler) handlePostBucket(w http.ResponseWriter, r *http.Request) {
 
 	var req models.DeleteObjectsRequest
 	if err := xml.NewDecoder(bodyReader).Decode(&req); err != nil {
+		if errors.Is(err, auth.ErrSignatureDoesNotMatch) {
+			writeMappedS3Error(w, r, err)
+			return
+		}
 		var maxErr *http.MaxBytesError
 		if errors.As(err, &maxErr) {
 			writeS3Error(w, r, s3ErrEntityTooLarge, r.URL.Path)
@@ -554,6 +734,15 @@ func (h *Handler) handlePostBucket(w http.ResponseWriter, r *http.Request) {
 			})
 			continue
 		}
+		if err := h.authorizeObjectAction(r, auth.ActionDeleteObject, bucket, obj.Key); err != nil {
+			apiErr := mapToS3Error(err)
+			response.Errors = append(response.Errors, models.DeleteError{
+				Key:     obj.Key,
+				Code:    apiErr.Code,
+				Message: apiErr.Message,
+			})
+			continue
+		}
 		keys = append(keys, obj.Key)
 	}
 
@@ -584,8 +773,8 @@ func (h *Handler) handlePostBucket(w http.ResponseWriter, r *http.Request) {
 
 func (h *Handler) handleDeleteObject(w http.ResponseWriter, r *http.Request) {
 	bucket := chi.URLParam(r, "bucket")
-	key := chi.URLParam(r, "*")
-	if apiErr := validateObjectKey(key); apiErr != nil {
+	key, apiErr := objectKeyFromRequest(r)
+	if apiErr != nil {
 		writeS3Error(w, r, *apiErr, r.URL.Path)
 		return
 	}
@@ -621,8 +810,8 @@ func (h *Handler) handleHeadBucket(w http.ResponseWriter, r *http.Request) {
 
 func (h *Handler) handleHeadObject(w http.ResponseWriter, r *http.Request) {
 	bucket := chi.URLParam(r, "bucket")
-	key := chi.URLParam(r, "*")
-	if apiErr := validateObjectKey(key); apiErr != nil {
+	key, apiErr := objectKeyFromRequest(r)
+	if apiErr != nil {
 		writeS3Error(w, r, *apiErr, r.URL.Path)
 		return
 	}

api/aws_chunked_test.go

@@ -0,0 +1,115 @@
+package api
+
+import (
+	"errors"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"fs/service"
+)
+
+func TestShouldDecodeAWSChunkedPayloadUnsignedTrailerMode(t *testing.T) {
+	t.Parallel()
+
+	req, err := http.NewRequest(http.MethodPut, "http://example.com/b/k", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("x-amz-content-sha256", "STREAMING-UNSIGNED-PAYLOAD-TRAILER")
+	if !shouldDecodeAWSChunkedPayload(req) {
+		t.Fatalf("expected shouldDecodeAWSChunkedPayload to return true for STREAMING-UNSIGNED-PAYLOAD-TRAILER")
+	}
+}
+
+func TestUnsupportedAWSChunkedContentEncodingWithoutStreamingMode(t *testing.T) {
+	t.Parallel()
+
+	req, err := http.NewRequest(http.MethodPut, "http://example.com/b/k", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("Content-Encoding", "aws-chunked")
+	req.Header.Set("x-amz-content-sha256", "UNSIGNED-PAYLOAD")
+
+	if !hasUnsupportedAWSChunkedPayload(req) {
+		t.Fatalf("expected aws-chunked content encoding without streaming mode to be unsupported")
+	}
+	if shouldDecodeAWSChunkedPayload(req) {
+		t.Fatalf("non-streaming aws-chunked content encoding must not trigger decoding")
+	}
+}
+
+func TestPutObjectRejectsUnsignedAWSChunkedContentEncoding(t *testing.T) {
+	handler, svc := newUploadLimitHandler(t, 1024)
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("CreateBucket: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodPut, "/test-bucket/object.txt", strings.NewReader("4\r\nWiki\r\n0\r\n\r\n"))
+	req.Header.Set("Content-Encoding", "aws-chunked")
+	req.Header.Set("x-amz-content-sha256", "UNSIGNED-PAYLOAD")
+	rec := httptest.NewRecorder()
+
+	handler.router.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusBadRequest {
+		t.Fatalf("status = %d, want %d body=%s", rec.Code, http.StatusBadRequest, rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), "InvalidArgument") {
+		t.Fatalf("expected InvalidArgument response, body=%s", rec.Body.String())
+	}
+}
+
+func TestAWSChunkedReaderPassThroughForPlainPayload(t *testing.T) {
+	t.Parallel()
+
+	plain := "PAR1\x00\x01\x02\x03binary-without-aws-chunked-header"
+	reader := newAWSChunkedDecodingReader(strings.NewReader(plain))
+	defer reader.Close()
+
+	out, err := io.ReadAll(reader)
+	if err != nil {
+		t.Fatalf("read failed: %v", err)
+	}
+	if string(out) != plain {
+		t.Fatalf("unexpected passthrough result: got %q want %q", string(out), plain)
+	}
+}
+
+func TestAWSChunkedReaderDecodesChunkedPayload(t *testing.T) {
+	t.Parallel()
+
+	encoded := "" +
+		"4\r\nWiki\r\n" +
+		"5\r\npedia\r\n" +
+		"0\r\n" +
+		"x-amz-checksum-crc32:xxxx\r\n" +
+		"\r\n"
+
+	reader := newAWSChunkedDecodingReader(strings.NewReader(encoded))
+	defer reader.Close()
+
+	out, err := io.ReadAll(reader)
+	if err != nil {
+		t.Fatalf("read failed: %v", err)
+	}
+	if string(out) != "Wikipedia" {
+		t.Fatalf("decoded payload mismatch: got %q want %q", string(out), "Wikipedia")
+	}
+}
+
+func TestAWSChunkedReaderRejectsOversizedChunkHeader(t *testing.T) {
+	t.Parallel()
+
+	encoded := strings.Repeat("f", maxAWSChunkedLineBytes+1) + "\n"
+	reader := newAWSChunkedDecodingReader(strings.NewReader(encoded))
+	defer reader.Close()
+
+	_, err := io.ReadAll(reader)
+	if !errors.Is(err, service.ErrEntityTooLarge) {
+		t.Fatalf("read error = %v, want ErrEntityTooLarge", err)
+	}
+}

api/multi_delete_auth_test.go

@@ -0,0 +1,283 @@
+package api
+
+import (
+	"bytes"
+	"context"
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"errors"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"path/filepath"
+	"sort"
+	"strings"
+	"testing"
+	"time"
+
+	"fs/auth"
+	"fs/logging"
+	"fs/metadata"
+	"fs/models"
+	"fs/service"
+	"fs/storage"
+
+	"github.com/go-chi/chi/v5"
+)
+
+func newAuthorizedDeleteHandler(t *testing.T) (*Handler, *service.ObjectService, *auth.Service) {
+	t.Helper()
+
+	root := t.TempDir()
+	md, err := metadata.NewMetadataHandler(filepath.Join(root, "metadata.db"))
+	if err != nil {
+		t.Fatalf("new metadata handler: %v", err)
+	}
+	blob, err := storage.NewBlobStore(root, 1024)
+	if err != nil {
+		t.Fatalf("new blob store: %v", err)
+	}
+	svc := service.NewObjectService(md, blob, time.Hour)
+	t.Cleanup(func() {
+		_ = svc.Close()
+	})
+
+	masterKey := base64.StdEncoding.EncodeToString(make([]byte, 32))
+	authSvc, err := auth.NewService(auth.ConfigFromValues(
+		true,
+		"us-east-1",
+		0,
+		0,
+		masterKey,
+		"",
+		"",
+		"",
+	), md)
+	if err != nil {
+		t.Fatalf("new auth service: %v", err)
+	}
+
+	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
+	handler := NewHandler(svc, logger, logging.Config{}, authSvc, false)
+	return handler, svc, authSvc
+}
+
+func newBucketPostRequest(bucket, body string) *http.Request {
+	req := httptest.NewRequest(http.MethodPost, "/"+bucket+"?delete", strings.NewReader(body))
+	rctx := chi.NewRouteContext()
+	rctx.URLParams.Add("bucket", bucket)
+	return req.WithContext(context.WithValue(req.Context(), chi.RouteCtxKey, rctx))
+}
+
+func withAuthContext(req *http.Request, accessKeyID string) *http.Request {
+	authCtx := auth.RequestContext{
+		Authenticated: true,
+		AccessKeyID:   accessKeyID,
+		AuthType:      "test",
+	}
+	return req.WithContext(auth.WithRequestContext(req.Context(), authCtx))
+}
+
+func createDeleteUser(t *testing.T, authSvc *auth.Service, prefix string) {
+	t.Helper()
+	createDeleteUserWithStatements(t, authSvc, []models.AuthPolicyStatement{
+		{
+			Effect:  "allow",
+			Actions: []string{"s3:DeleteObject"},
+			Bucket:  "test-bucket",
+			Prefix:  prefix,
+		},
+	})
+}
+
+func createDeleteUserWithStatements(t *testing.T, authSvc *auth.Service, statements []models.AuthPolicyStatement) {
+	t.Helper()
+	_, err := authSvc.CreateUser(auth.CreateUserInput{
+		AccessKeyID: "delete-user",
+		SecretKey:   "delete-secret-1",
+		Policy: models.AuthPolicy{
+			Statements: statements,
+		},
+	})
+	if err != nil {
+		t.Fatalf("create delete user: %v", err)
+	}
+}
+
+func putTestObject(t *testing.T, svc *service.ObjectService, key string) {
+	t.Helper()
+	_, err := svc.PutObject("test-bucket", key, "text/plain", bytes.NewReader([]byte("data")))
+	if err != nil {
+		t.Fatalf("put object %q: %v", key, err)
+	}
+}
+
+func TestMultiDeleteAuthorizesEveryKey(t *testing.T) {
+	handler, svc, authSvc := newAuthorizedDeleteHandler(t)
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("create bucket: %v", err)
+	}
+	createDeleteUser(t, authSvc, "allowed/")
+	putTestObject(t, svc, "allowed/file.txt")
+	putTestObject(t, svc, "private/file.txt")
+
+	body := `<Delete><Object><Key>allowed/file.txt</Key></Object><Object><Key>private/file.txt</Key></Object></Delete>`
+	req := withAuthContext(newBucketPostRequest("test-bucket", body), "delete-user")
+	rec := httptest.NewRecorder()
+
+	handler.handlePostBucket(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("unexpected status: got %d body=%s", rec.Code, rec.Body.String())
+	}
+	responseBody := rec.Body.String()
+	if !strings.Contains(responseBody, "<Deleted>") || !strings.Contains(responseBody, "allowed/file.txt") {
+		t.Fatalf("expected allowed key to be deleted, body=%s", responseBody)
+	}
+	if !strings.Contains(responseBody, "<Error>") || !strings.Contains(responseBody, "private/file.txt") || !strings.Contains(responseBody, "AccessDenied") {
+		t.Fatalf("expected denied key error, body=%s", responseBody)
+	}
+	if _, err := svc.HeadObject("test-bucket", "allowed/file.txt"); !errors.Is(err, metadata.ErrObjectNotFound) {
+		t.Fatalf("allowed object should be deleted, got err=%v", err)
+	}
+	if _, err := svc.HeadObject("test-bucket", "private/file.txt"); err != nil {
+		t.Fatalf("private object should remain: %v", err)
+	}
+}
+
+func TestMultiDeleteAllowsScopedKeys(t *testing.T) {
+	handler, svc, authSvc := newAuthorizedDeleteHandler(t)
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("create bucket: %v", err)
+	}
+	createDeleteUser(t, authSvc, "allowed/")
+	putTestObject(t, svc, "allowed/file.txt")
+
+	body := `<Delete><Object><Key>allowed/file.txt</Key></Object></Delete>`
+	req := withAuthContext(newBucketPostRequest("test-bucket", body), "delete-user")
+	rec := httptest.NewRecorder()
+
+	handler.handlePostBucket(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("unexpected status: got %d body=%s", rec.Code, rec.Body.String())
+	}
+	if strings.Contains(rec.Body.String(), "<Error>") {
+		t.Fatalf("unexpected delete error body=%s", rec.Body.String())
+	}
+	if _, err := svc.HeadObject("test-bucket", "allowed/file.txt"); !errors.Is(err, metadata.ErrObjectNotFound) {
+		t.Fatalf("allowed object should be deleted, got err=%v", err)
+	}
+}
+
+func TestMultiDeleteRouteAuthorizesKeysAfterMiddleware(t *testing.T) {
+	handler, svc, authSvc := newAuthorizedDeleteHandler(t)
+	handler.setupRoutes()
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("create bucket: %v", err)
+	}
+	createDeleteUserWithStatements(t, authSvc, []models.AuthPolicyStatement{
+		{Effect: "allow", Actions: []string{"s3:DeleteObject"}, Bucket: "test-bucket", Prefix: "allowed/"},
+		{Effect: "deny", Actions: []string{"s3:DeleteObject"}, Bucket: "test-bucket", Prefix: "private/"},
+	})
+	putTestObject(t, svc, "allowed/file.txt")
+	putTestObject(t, svc, "private/file.txt")
+
+	body := `<Delete><Object><Key>allowed/file.txt</Key></Object><Object><Key>private/file.txt</Key></Object></Delete>`
+	req := httptest.NewRequest(http.MethodPost, "/test-bucket?delete", strings.NewReader(body))
+	signTestSigV4Request(t, req, "delete-user", "delete-secret-1")
+	rec := httptest.NewRecorder()
+
+	handler.router.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("unexpected status: got %d body=%s", rec.Code, rec.Body.String())
+	}
+	responseBody := rec.Body.String()
+	if !strings.Contains(responseBody, "allowed/file.txt") || !strings.Contains(responseBody, "<Deleted>") {
+		t.Fatalf("expected allowed key deletion, body=%s", responseBody)
+	}
+	if !strings.Contains(responseBody, "private/file.txt") || !strings.Contains(responseBody, "AccessDenied") {
+		t.Fatalf("expected per-key AccessDenied, body=%s", responseBody)
+	}
+	if _, err := svc.HeadObject("test-bucket", "allowed/file.txt"); !errors.Is(err, metadata.ErrObjectNotFound) {
+		t.Fatalf("allowed object should be deleted, got err=%v", err)
+	}
+	if _, err := svc.HeadObject("test-bucket", "private/file.txt"); err != nil {
+		t.Fatalf("private object should remain: %v", err)
+	}
+}
+
+func signTestSigV4Request(t *testing.T, req *http.Request, accessKeyID, secretKey string) {
+	t.Helper()
+
+	amzDate := time.Now().UTC().Format("20060102T150405Z")
+	date := amzDate[:8]
+	region := "us-east-1"
+	serviceName := "s3"
+	scope := strings.Join([]string{date, region, serviceName, "aws4_request"}, "/")
+	signedHeaders := []string{"host", "x-amz-content-sha256", "x-amz-date"}
+	signedHeadersRaw := strings.Join(signedHeaders, ";")
+	payloadHash := "UNSIGNED-PAYLOAD"
+
+	req.Header.Set("x-amz-date", amzDate)
+	req.Header.Set("x-amz-content-sha256", payloadHash)
+	canonicalRequest := strings.Join([]string{
+		req.Method,
+		req.URL.EscapedPath(),
+		canonicalTestQuery(req.URL.RawQuery),
+		"host:" + strings.TrimSpace(req.Host) + "\n" +
+			"x-amz-content-sha256:" + payloadHash + "\n" +
+			"x-amz-date:" + amzDate + "\n",
+		signedHeadersRaw,
+		payloadHash,
+	}, "\n")
+	canonicalHash := sha256.Sum256([]byte(canonicalRequest))
+	stringToSign := strings.Join([]string{
+		"AWS4-HMAC-SHA256",
+		amzDate,
+		scope,
+		hex.EncodeToString(canonicalHash[:]),
+	}, "\n")
+	signingKey := testHMAC(testHMAC(testHMAC(testHMAC([]byte("AWS4"+secretKey), date), region), serviceName), "aws4_request")
+	signature := hex.EncodeToString(testHMAC(signingKey, stringToSign))
+
+	req.Header.Set("Authorization", "AWS4-HMAC-SHA256 "+
+		"Credential="+accessKeyID+"/"+scope+", "+
+		"SignedHeaders="+signedHeadersRaw+", "+
+		"Signature="+signature)
+}
+
+func canonicalTestQuery(rawQuery string) string {
+	values, _ := url.ParseQuery(rawQuery)
+	pairs := make([]string, 0)
+	for key, valueList := range values {
+		if len(valueList) == 0 {
+			pairs = append(pairs, awsTestQueryEscape(key)+"=")
+			continue
+		}
+		for _, value := range valueList {
+			pairs = append(pairs, awsTestQueryEscape(key)+"="+awsTestQueryEscape(value))
+		}
+	}
+	sort.Strings(pairs)
+	return strings.Join(pairs, "&")
+}
+
+func awsTestQueryEscape(value string) string {
+	encoded := url.QueryEscape(value)
+	encoded = strings.ReplaceAll(encoded, "+", "%20")
+	encoded = strings.ReplaceAll(encoded, "*", "%2A")
+	encoded = strings.ReplaceAll(encoded, "%7E", "~")
+	return encoded
+}
+
+func testHMAC(key []byte, value string) []byte {
+	mac := hmac.New(sha256.New, key)
+	_, _ = mac.Write([]byte(value))
+	return mac.Sum(nil)
+}

api/object_copy_test.go

@@ -0,0 +1,107 @@
+package api
+
+import (
+	"bytes"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"fs/logging"
+	"fs/metadata"
+	"fs/service"
+	"fs/storage"
+)
+
+func newTestObjectHandler(t *testing.T) (*Handler, *service.ObjectService) {
+	t.Helper()
+
+	root := t.TempDir()
+	md, err := metadata.NewMetadataHandler(filepath.Join(root, "metadata.db"))
+	if err != nil {
+		t.Fatalf("new metadata handler: %v", err)
+	}
+	blob, err := storage.NewBlobStore(root, 1024)
+	if err != nil {
+		t.Fatalf("new blob store: %v", err)
+	}
+	svc := service.NewObjectService(md, blob, time.Hour)
+	t.Cleanup(func() {
+		_ = svc.Close()
+	})
+
+	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
+	handler := NewHandler(svc, logger, logging.Config{}, nil, false)
+	handler.setupRoutes()
+	return handler, svc
+}
+
+func TestPutObjectStoresDecodedKey(t *testing.T) {
+	handler, svc := newTestObjectHandler(t)
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("create bucket: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodPut, "/test-bucket/jsp-data-raw/vehicle_positions/year%3D2026/month%3D03/day%3D12/file.parquet", bytes.NewReader([]byte("PAR1data")))
+	rec := httptest.NewRecorder()
+	handler.router.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("unexpected status: got %d body=%s", rec.Code, rec.Body.String())
+	}
+
+	_, err := svc.HeadObject("test-bucket", "jsp-data-raw/vehicle_positions/year=2026/month=03/day=12/file.parquet")
+	if err != nil {
+		t.Fatalf("head decoded key: %v", err)
+	}
+
+	getReq := httptest.NewRequest(http.MethodGet, "/test-bucket/jsp-data-raw/vehicle_positions/year=2026/month=03/day=12/file.parquet", nil)
+	getRec := httptest.NewRecorder()
+	handler.router.ServeHTTP(getRec, getReq)
+	if getRec.Code != http.StatusOK {
+		t.Fatalf("unexpected get status: got %d body=%s", getRec.Code, getRec.Body.String())
+	}
+	if got := getRec.Body.String(); got != "PAR1data" {
+		t.Fatalf("unexpected get body: got %q", got)
+	}
+}
+
+func TestCopyObjectCopiesCanonicalObject(t *testing.T) {
+	handler, svc := newTestObjectHandler(t)
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("create bucket: %v", err)
+	}
+
+	putReq := httptest.NewRequest(http.MethodPut, "/test-bucket/source/year%3D2026/file.parquet", bytes.NewReader([]byte("PAR1copy")))
+	putRec := httptest.NewRecorder()
+	handler.router.ServeHTTP(putRec, putReq)
+	if putRec.Code != http.StatusOK {
+		t.Fatalf("unexpected put status: got %d body=%s", putRec.Code, putRec.Body.String())
+	}
+
+	copyReq := httptest.NewRequest(http.MethodPut, "/test-bucket/copied/year=2026/file.parquet", http.NoBody)
+	copyReq.Header.Set("x-amz-copy-source", "/test-bucket/source/year%3D2026/file.parquet")
+	copyRec := httptest.NewRecorder()
+	handler.router.ServeHTTP(copyRec, copyReq)
+
+	if copyRec.Code != http.StatusOK {
+		t.Fatalf("unexpected copy status: got %d body=%s", copyRec.Code, copyRec.Body.String())
+	}
+	if !strings.Contains(copyRec.Body.String(), "<CopyObjectResult") {
+		t.Fatalf("unexpected copy response body: %s", copyRec.Body.String())
+	}
+
+	getReq := httptest.NewRequest(http.MethodGet, "/test-bucket/copied/year=2026/file.parquet", nil)
+	getRec := httptest.NewRecorder()
+	handler.router.ServeHTTP(getRec, getReq)
+	if getRec.Code != http.StatusOK {
+		t.Fatalf("unexpected get status after copy: got %d body=%s", getRec.Code, getRec.Body.String())
+	}
+	if got := getRec.Body.String(); got != "PAR1copy" {
+		t.Fatalf("unexpected copied body: got %q", got)
+	}
+}

api/s3_errors.go

@@ -174,6 +174,8 @@ func mapToS3Error(err error) s3APIError {
 		return s3ErrMalformedXML
 	case errors.Is(err, service.ErrEntityTooSmall):
 		return s3ErrEntityTooSmall
+	case errors.Is(err, service.ErrEntityTooLarge):
+		return s3ErrEntityTooLarge
 	case errors.Is(err, auth.ErrAccessDenied):
 		return s3ErrAccessDenied
 	case errors.Is(err, auth.ErrInvalidAccessKeyID):

api/upload_limit_test.go

@@ -0,0 +1,79 @@
+package api
+
+import (
+	"bytes"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"fs/logging"
+	"fs/metadata"
+	"fs/service"
+	"fs/storage"
+)
+
+func TestPutObjectReturnsEntityTooLarge(t *testing.T) {
+	handler, svc := newUploadLimitHandler(t, 4)
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("CreateBucket: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodPut, "/test-bucket/too-large.txt", strings.NewReader("12345"))
+	rec := httptest.NewRecorder()
+	handler.router.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusRequestEntityTooLarge {
+		t.Fatalf("status = %d, want %d body=%s", rec.Code, http.StatusRequestEntityTooLarge, rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), "EntityTooLarge") {
+		t.Fatalf("expected EntityTooLarge response, body=%s", rec.Body.String())
+	}
+}
+
+func TestUploadPartReturnsEntityTooLarge(t *testing.T) {
+	handler, svc := newUploadLimitHandler(t, 4)
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("CreateBucket: %v", err)
+	}
+	upload, err := svc.CreateMultipartUpload("test-bucket", "object.txt")
+	if err != nil {
+		t.Fatalf("CreateMultipartUpload: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodPut, "/test-bucket/object.txt?partNumber=1&uploadId="+upload.UploadID, bytes.NewReader([]byte("12345")))
+	rec := httptest.NewRecorder()
+	handler.router.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusRequestEntityTooLarge {
+		t.Fatalf("status = %d, want %d body=%s", rec.Code, http.StatusRequestEntityTooLarge, rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), "EntityTooLarge") {
+		t.Fatalf("expected EntityTooLarge response, body=%s", rec.Body.String())
+	}
+}
+
+func newUploadLimitHandler(t *testing.T, maxUploadSize int64) (*Handler, *service.ObjectService) {
+	t.Helper()
+	root := t.TempDir()
+	md, err := metadata.NewMetadataHandler(filepath.Join(root, "metadata.db"))
+	if err != nil {
+		t.Fatalf("new metadata handler: %v", err)
+	}
+	blob, err := storage.NewBlobStore(root, 4)
+	if err != nil {
+		t.Fatalf("new blob store: %v", err)
+	}
+	svc := service.NewObjectService(md, blob, time.Hour, maxUploadSize)
+	t.Cleanup(func() {
+		_ = svc.Close()
+	})
+	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
+	handler := NewHandler(svc, logger, logging.Config{}, nil, false)
+	handler.setupRoutes()
+	return handler, svc
+}

app/server.go

@@ -2,7 +2,6 @@ package app
 
 import (
 	"context"
-	"fmt"
 	"fs/api"
 	"fs/auth"
 	"fs/logging"
@@ -40,6 +39,7 @@ func RunServer(ctx context.Context) error {
 		"audit_log", logConfig.Audit,
 		"data_path", config.DataPath,
 		"multipart_retention_hours", int(config.MultipartCleanupRetention/time.Hour),
+		"max_object_upload_bytes", config.MaxObjectUploadBytes,
 		"auth_enabled", authConfig.Enabled,
 		"auth_region", authConfig.Region,
 		"admin_api_enabled", config.AdminAPIEnabled,
@@ -64,7 +64,7 @@ func RunServer(ctx context.Context) error {
 		return err
 	}
 
-	objectService := service.NewObjectService(metadataHandler, blobHandler, config.MultipartCleanupRetention)
+	objectService := service.NewObjectService(metadataHandler, blobHandler, config.MultipartCleanupRetention, config.MaxObjectUploadBytes)
 	authService, err := auth.NewService(authConfig, metadataHandler)
 	if err != nil {
 		_ = metadataHandler.Close()
@@ -85,7 +85,7 @@ func RunServer(ctx context.Context) error {
 
 	if err := handler.Start(ctx, addr); err != nil {
 		logger.Error("server_stopped_with_error", "error", err)
-		return fmt.Errorf("server start failed: %w", err)
+		return err
 	}
 	return nil
 }

auth/README.md

@@ -94,9 +94,11 @@ For each non-health request:
 6. Decrypt stored secret using master key.
 7. Recompute canonical request and expected signature.
 8. Compare signatures.
-9. Resolve target action from request.
-10. Evaluate policy; deny overrides allow.
-11. Store auth result in request context and continue.
+9. Reject signed streaming payload modes that require per-chunk signature verification.
+10. Wrap fixed-size signed payloads so the actual body must match `x-amz-content-sha256`.
+11. Resolve target action from request.
+12. Evaluate policy; deny overrides allow.
+13. Store auth result in request context and continue.
 
 ## Authorization Semantics
 Policy evaluator rules:
@@ -106,6 +108,9 @@ Policy evaluator rules:
   - action: `*` or `s3:*`
   - bucket: `*`
   - prefix: `*`
+- Object actions apply `prefix` to the object key.
+- `ListBucket` applies `prefix` to the requested list `prefix` query value; a scoped list policy such as `prefix=backups/` does not allow an empty-prefix or sibling-prefix bucket listing.
+- Multi-object delete is authorized per object key after the XML body is parsed; denied keys are returned as per-key `AccessDenied` errors and are not deleted.
 
 Action resolution includes:
 - bucket APIs (`CreateBucket`, `ListBucket`, `HeadBucket`, `DeleteBucket`)
@@ -137,14 +142,7 @@ Each audit entry includes method, path, remote IP, and request ID (if present).
 
 ## Current Scope / Limitations
 - No STS/session-token auth yet.
-- No admin API for managing multiple users yet.
+- Signed aws-chunked streaming payloads are not accepted until per-chunk signature verification is implemented. Unsigned streaming payload modes can still be decoded by the API layer.
 - Policy language is intentionally minimal, not full IAM.
 - No automatic key rotation workflows.
-
-## Practical Next Step
-To support multiple users cleanly, add admin operations in auth service + API:
-- create user
-- rotate secret
-- set policy
-- disable/enable
-- delete user
+- No key rotation endpoint for existing users yet.

auth/action.go

@@ -27,6 +27,18 @@ type RequestTarget struct {
 	Action Action
 	Bucket string
 	Key    string
+	Prefix string
+}
+
+func RequiresHandlerAuthorization(r *http.Request) bool {
+	if r == nil || r.URL == nil {
+		return false
+	}
+	if r.Method == http.MethodPost {
+		_, isDelete := r.URL.Query()["delete"]
+		return isDelete
+	}
+	return false
 }
 
 func resolveTarget(r *http.Request) RequestTarget {
@@ -51,7 +63,7 @@ func resolveTarget(r *http.Request) RequestTarget {
 		case http.MethodDelete:
 			return RequestTarget{Action: ActionDeleteBucket, Bucket: bucket}
 		case http.MethodGet:
-			return RequestTarget{Action: ActionListBucket, Bucket: bucket}
+			return RequestTarget{Action: ActionListBucket, Bucket: bucket, Prefix: r.URL.Query().Get("prefix")}
 		case http.MethodPost:
 			if _, ok := r.URL.Query()["delete"]; ok {
 				return RequestTarget{Action: ActionDeleteObject, Bucket: bucket}

auth/action_test.go

@@ -0,0 +1,39 @@
+package auth
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestResolveTargetIncludesListBucketPrefix(t *testing.T) {
+	req := httptest.NewRequest(http.MethodGet, "http://example.com/test-bucket?list-type=2&prefix=allowed/", nil)
+
+	target := resolveTarget(req)
+
+	if target.Action != ActionListBucket {
+		t.Fatalf("action = %q, want %q", target.Action, ActionListBucket)
+	}
+	if target.Bucket != "test-bucket" {
+		t.Fatalf("bucket = %q, want test-bucket", target.Bucket)
+	}
+	if target.Prefix != "allowed/" {
+		t.Fatalf("prefix = %q, want allowed/", target.Prefix)
+	}
+	if target.Key != "" {
+		t.Fatalf("key = %q, want empty", target.Key)
+	}
+}
+
+func TestResolveTargetListBucketWithoutPrefix(t *testing.T) {
+	req := httptest.NewRequest(http.MethodGet, "http://example.com/test-bucket", nil)
+
+	target := resolveTarget(req)
+
+	if target.Action != ActionListBucket {
+		t.Fatalf("action = %q, want %q", target.Action, ActionListBucket)
+	}
+	if target.Prefix != "" {
+		t.Fatalf("prefix = %q, want empty", target.Prefix)
+	}
+}

auth/middleware.go

@@ -1,11 +1,16 @@
 package auth
 
 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"errors"
 	"fs/metrics"
+	"hash"
+	"io"
 	"log/slog"
 	"net"
 	"net/http"
+	"strings"
 
 	"github.com/go-chi/chi/v5/middleware"
 )
@@ -55,6 +60,16 @@ func Middleware(
 				return
 			}
 
+			if err := wrapPayloadHashVerifier(r); err != nil {
+				metrics.Default.ObserveAuth("error", "sigv4", authErrorClass(err))
+				if onError != nil {
+					onError(w, r, err)
+					return
+				}
+				http.Error(w, http.StatusText(http.StatusForbidden), http.StatusForbidden)
+				return
+			}
+
 			metrics.Default.ObserveAuth("ok", resolvedCtx.AuthType, "none")
 			if auditEnabled && logger != nil {
 				requestID := middleware.GetReqID(r.Context())
@@ -75,6 +90,65 @@ func Middleware(
 	}
 }
 
+func wrapPayloadHashVerifier(r *http.Request) error {
+	if r == nil || r.Body == nil || r.Body == http.NoBody {
+		return nil
+	}
+	payloadHash := resolvePayloadHash(r, false)
+	if !payloadHashRequiresVerification(payloadHash) {
+		return nil
+	}
+	if !isHexSHA256(payloadHash) {
+		return ErrAuthorizationHeaderMalformed
+	}
+	expected, err := hex.DecodeString(strings.ToLower(payloadHash))
+	if err != nil {
+		return ErrAuthorizationHeaderMalformed
+	}
+	r.Body = &payloadHashVerifyingReadCloser{
+		inner:    r.Body,
+		hasher:   sha256.New(),
+		expected: expected,
+	}
+	return nil
+}
+
+type payloadHashVerifyingReadCloser struct {
+	inner    io.ReadCloser
+	hasher   hash.Hash
+	expected []byte
+	done     bool
+}
+
+func (r *payloadHashVerifyingReadCloser) Read(p []byte) (int, error) {
+	n, err := r.inner.Read(p)
+	if n > 0 {
+		_, _ = r.hasher.Write(p[:n])
+	}
+	if err == io.EOF && !r.done {
+		r.done = true
+		if !equalBytes(r.hasher.Sum(nil), r.expected) {
+			return n, ErrSignatureDoesNotMatch
+		}
+	}
+	return n, err
+}
+
+func (r *payloadHashVerifyingReadCloser) Close() error {
+	return r.inner.Close()
+}
+
+func equalBytes(left, right []byte) bool {
+	if len(left) != len(right) {
+		return false
+	}
+	var diff byte
+	for i := range left {
+		diff |= left[i] ^ right[i]
+	}
+	return diff == 0
+}
+
 func authErrorClass(err error) string {
 	switch {
 	case errors.Is(err, ErrInvalidAccessKeyID):

auth/payload_hash_test.go

@@ -0,0 +1,75 @@
+package auth
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+)
+
+func TestPayloadHashVerifierAllowsMatchingBody(t *testing.T) {
+	body := "payload"
+	req := newPayloadHashRequest(t, body, body)
+
+	if err := wrapPayloadHashVerifier(req); err != nil {
+		t.Fatalf("wrapPayloadHashVerifier returned error: %v", err)
+	}
+	got, err := io.ReadAll(req.Body)
+	if err != nil {
+		t.Fatalf("ReadAll returned error: %v", err)
+	}
+	if string(got) != body {
+		t.Fatalf("unexpected body: got %q want %q", string(got), body)
+	}
+}
+
+func TestPayloadHashVerifierRejectsMismatchedBody(t *testing.T) {
+	req := newPayloadHashRequest(t, "signed-payload", "actual-payload")
+
+	if err := wrapPayloadHashVerifier(req); err != nil {
+		t.Fatalf("wrapPayloadHashVerifier returned error: %v", err)
+	}
+	_, err := io.ReadAll(req.Body)
+	if !errors.Is(err, ErrSignatureDoesNotMatch) {
+		t.Fatalf("ReadAll error = %v, want ErrSignatureDoesNotMatch", err)
+	}
+}
+
+func TestPayloadSigningRejectsSignedStreamingMode(t *testing.T) {
+	req, err := http.NewRequest(http.MethodPut, "http://example.com/b/k", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("x-amz-content-sha256", "STREAMING-AWS4-HMAC-SHA256-PAYLOAD")
+
+	err = validatePayloadSigningMode(req, &sigV4Input{})
+	if !errors.Is(err, ErrAuthorizationHeaderMalformed) {
+		t.Fatalf("validatePayloadSigningMode error = %v, want ErrAuthorizationHeaderMalformed", err)
+	}
+}
+
+func TestPayloadSigningAllowsUnsignedStreamingMode(t *testing.T) {
+	req, err := http.NewRequest(http.MethodPut, "http://example.com/b/k", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("x-amz-content-sha256", "STREAMING-UNSIGNED-PAYLOAD-TRAILER")
+
+	if err := validatePayloadSigningMode(req, &sigV4Input{}); err != nil {
+		t.Fatalf("validatePayloadSigningMode returned error: %v", err)
+	}
+}
+
+func newPayloadHashRequest(t *testing.T, signedBody, actualBody string) *http.Request {
+	t.Helper()
+	req, err := http.NewRequest(http.MethodPut, "http://example.com/b/k", strings.NewReader(actualBody))
+	if err != nil {
+		t.Fatal(err)
+	}
+	sum := sha256.Sum256([]byte(signedBody))
+	req.Header.Set("x-amz-content-sha256", hex.EncodeToString(sum[:]))
+	return req
+}

auth/policy.go

@@ -33,14 +33,16 @@ func statementMatches(stmt models.AuthPolicyStatement, target RequestTarget) boo
 	if !bucketMatches(stmt.Bucket, target.Bucket) {
 		return false
 	}
-	if target.Key == "" {
-		return true
-	}
-
 	prefix := strings.TrimSpace(stmt.Prefix)
 	if prefix == "" || prefix == "*" {
 		return true
 	}
+	if target.Key == "" {
+		if target.Action == ActionListBucket {
+			return strings.HasPrefix(target.Prefix, prefix)
+		}
+		return true
+	}
 	return strings.HasPrefix(target.Key, prefix)
 }
 

auth/policy_test.go

@@ -0,0 +1,52 @@
+package auth
+
+import (
+	"fs/models"
+	"testing"
+)
+
+func TestListBucketPolicyAppliesPrefix(t *testing.T) {
+	policy := &models.AuthPolicy{
+		Statements: []models.AuthPolicyStatement{
+			{
+				Effect:  "allow",
+				Actions: []string{"s3:ListBucket"},
+				Bucket:  "test-bucket",
+				Prefix:  "allowed/",
+			},
+		},
+	}
+
+	if !isAllowed(policy, RequestTarget{Action: ActionListBucket, Bucket: "test-bucket", Prefix: "allowed/"}) {
+		t.Fatalf("expected matching list prefix to be allowed")
+	}
+	if !isAllowed(policy, RequestTarget{Action: ActionListBucket, Bucket: "test-bucket", Prefix: "allowed/nested/"}) {
+		t.Fatalf("expected nested list prefix to be allowed")
+	}
+	if isAllowed(policy, RequestTarget{Action: ActionListBucket, Bucket: "test-bucket"}) {
+		t.Fatalf("expected empty list prefix to be denied")
+	}
+	if isAllowed(policy, RequestTarget{Action: ActionListBucket, Bucket: "test-bucket", Prefix: "private/"}) {
+		t.Fatalf("expected non-matching list prefix to be denied")
+	}
+}
+
+func TestWildcardListBucketPolicyAllowsAnyPrefix(t *testing.T) {
+	policy := &models.AuthPolicy{
+		Statements: []models.AuthPolicyStatement{
+			{
+				Effect:  "allow",
+				Actions: []string{"s3:ListBucket"},
+				Bucket:  "test-bucket",
+				Prefix:  "*",
+			},
+		},
+	}
+
+	if !isAllowed(policy, RequestTarget{Action: ActionListBucket, Bucket: "test-bucket"}) {
+		t.Fatalf("expected wildcard list policy to allow empty prefix")
+	}
+	if !isAllowed(policy, RequestTarget{Action: ActionListBucket, Bucket: "test-bucket", Prefix: "private/"}) {
+		t.Fatalf("expected wildcard list policy to allow arbitrary prefix")
+	}
+}

auth/service.go

@@ -152,6 +152,9 @@ func (s *Service) AuthenticateRequest(r *http.Request) (RequestContext, error) {
 	if err := validateSigV4Input(s.now(), s.cfg, input); err != nil {
 		return RequestContext{}, err
 	}
+	if err := validatePayloadSigningMode(r, input); err != nil {
+		return RequestContext{}, err
+	}
 
 	identity, err := s.store.GetAuthIdentity(input.AccessKeyID)
 	if err != nil {
@@ -185,6 +188,13 @@ func (s *Service) AuthenticateRequest(r *http.Request) (RequestContext, error) {
 			AuthType:      authType,
 		}, nil
 	}
+	if RequiresHandlerAuthorization(r) {
+		return RequestContext{
+			Authenticated: true,
+			AccessKeyID:   identity.AccessKeyID,
+			AuthType:      authType,
+		}, nil
+	}
 
 	policy, err := s.store.GetAuthPolicy(identity.AccessKeyID)
 	if err != nil {
@@ -205,6 +215,29 @@ func (s *Service) AuthenticateRequest(r *http.Request) (RequestContext, error) {
 	}, nil
 }
 
+func (s *Service) Authorize(accessKeyID string, target RequestTarget) error {
+	if !s.cfg.Enabled {
+		return nil
+	}
+
+	accessKeyID = strings.TrimSpace(accessKeyID)
+	if accessKeyID == "" {
+		return ErrAccessDenied
+	}
+	if target.Action == "" {
+		return ErrAccessDenied
+	}
+
+	policy, err := s.store.GetAuthPolicy(accessKeyID)
+	if err != nil {
+		return ErrAccessDenied
+	}
+	if !isAllowed(policy, target) {
+		return ErrAccessDenied
+	}
+	return nil
+}
+
 func (s *Service) CreateUser(input CreateUserInput) (*CreateUserResult, error) {
 	if !s.cfg.Enabled {
 		return nil, ErrAuthNotEnabled

auth/sigv4.go

@@ -210,6 +210,17 @@ func validateSigV4Input(now time.Time, cfg Config, input *sigV4Input) error {
 	return nil
 }
 
+func validatePayloadSigningMode(r *http.Request, input *sigV4Input) error {
+	payloadHash := resolvePayloadHash(r, input.Presigned)
+	if isSignedStreamingPayloadHash(payloadHash) {
+		return fmt.Errorf("%w: signed streaming payload verification is not supported", ErrAuthorizationHeaderMalformed)
+	}
+	if payloadHashRequiresVerification(payloadHash) && !isHexSHA256(payloadHash) {
+		return fmt.Errorf("%w: invalid x-amz-content-sha256", ErrAuthorizationHeaderMalformed)
+	}
+	return nil
+}
+
 func signatureMatches(secret string, r *http.Request, input *sigV4Input) (bool, error) {
 	payloadHash := resolvePayloadHash(r, input.Presigned)
 	canonicalRequest, err := buildCanonicalRequest(r, input.SignedHeaders, payloadHash, input.Presigned)
@@ -233,6 +244,34 @@ func resolvePayloadHash(r *http.Request, presigned bool) string {
 	return hash
 }
 
+func isSignedStreamingPayloadHash(payloadHash string) bool {
+	payloadHash = strings.ToUpper(strings.TrimSpace(payloadHash))
+	return strings.HasPrefix(payloadHash, "STREAMING-AWS4-HMAC-SHA256-PAYLOAD")
+}
+
+func payloadHashRequiresVerification(payloadHash string) bool {
+	payloadHash = strings.ToUpper(strings.TrimSpace(payloadHash))
+	if payloadHash == "" || payloadHash == "UNSIGNED-PAYLOAD" {
+		return false
+	}
+	if strings.HasPrefix(payloadHash, "STREAMING-UNSIGNED-PAYLOAD") {
+		return false
+	}
+	return true
+}
+
+func isHexSHA256(value string) bool {
+	if len(value) != sha256.Size*2 {
+		return false
+	}
+	for _, ch := range value {
+		if (ch < '0' || ch > '9') && (ch < 'a' || ch > 'f') && (ch < 'A' || ch > 'F') {
+			return false
+		}
+	}
+	return true
+}
+
 func buildCanonicalRequest(r *http.Request, signedHeaders []string, payloadHash string, presigned bool) (string, error) {
 	canonicalURI := canonicalPath(r.URL)
 	canonicalQuery := canonicalQueryString(r.URL.RawQuery, presigned)
@@ -259,7 +298,57 @@ func canonicalPath(u *url.URL) string {
 	if path == "" {
 		return "/"
 	}
-	return path
+	return awsEncodePath(path)
+}
+
+func awsEncodePath(path string) string {
+	var b strings.Builder
+	b.Grow(len(path))
+	for i := 0; i < len(path); i++ {
+		ch := path[i]
+		if ch == '/' || isUnreserved(ch) {
+			b.WriteByte(ch)
+			continue
+		}
+		if ch == '%' && i+2 < len(path) && isHex(path[i+1]) && isHex(path[i+2]) {
+			b.WriteByte('%')
+			b.WriteByte(toUpperHex(path[i+1]))
+			b.WriteByte(toUpperHex(path[i+2]))
+			i += 2
+			continue
+		}
+		b.WriteByte('%')
+		b.WriteByte(hexUpper(ch >> 4))
+		b.WriteByte(hexUpper(ch & 0x0F))
+	}
+	return b.String()
+}
+
+func isUnreserved(ch byte) bool {
+	return (ch >= 'A' && ch <= 'Z') ||
+		(ch >= 'a' && ch <= 'z') ||
+		(ch >= '0' && ch <= '9') ||
+		ch == '-' || ch == '_' || ch == '.' || ch == '~'
+}
+
+func isHex(ch byte) bool {
+	return (ch >= '0' && ch <= '9') ||
+		(ch >= 'a' && ch <= 'f') ||
+		(ch >= 'A' && ch <= 'F')
+}
+
+func toUpperHex(ch byte) byte {
+	if ch >= 'a' && ch <= 'f' {
+		return ch - ('a' - 'A')
+	}
+	return ch
+}
+
+func hexUpper(nibble byte) byte {
+	if nibble < 10 {
+		return '0' + nibble
+	}
+	return 'A' + (nibble - 10)
 }
 
 type queryPair struct {

auth/sigv4_test.go

@@ -0,0 +1,50 @@
+package auth
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+)
+
+func TestCanonicalPathEncodesEquals(t *testing.T) {
+	u := &url.URL{Path: "/test-bucket/jsp-data-raw/year=2026/month=03/day=12/vehicle_positions.parquet"}
+	got := canonicalPath(u)
+	want := "/test-bucket/jsp-data-raw/year%3D2026/month%3D03/day%3D12/vehicle_positions.parquet"
+	if got != want {
+		t.Fatalf("unexpected canonical path: got %q want %q", got, want)
+	}
+}
+
+func TestCanonicalPathPreservesExistingEscapes(t *testing.T) {
+	u, err := url.Parse("http://localhost:2600/test-bucket/jsp-data-raw/year%3d2026/file%2Eparquet")
+	if err != nil {
+		t.Fatalf("url.Parse failed: %v", err)
+	}
+	got := canonicalPath(u)
+	want := "/test-bucket/jsp-data-raw/year%3D2026/file%2Eparquet"
+	if got != want {
+		t.Fatalf("unexpected canonical path: got %q want %q", got, want)
+	}
+}
+
+func TestBuildCanonicalRequestUsesAwsEncodedPath(t *testing.T) {
+	req := httptest.NewRequest(http.MethodGet, "http://localhost:2600/test-bucket/jsp-data-raw/year=2026/month=03/day=12/vehicle_positions.parquet", nil)
+	req.Header.Set("x-amz-date", "20260313T120000Z")
+	req.Header.Set("x-amz-content-sha256", "UNSIGNED-PAYLOAD")
+
+	canonical, err := buildCanonicalRequest(req, []string{"host", "x-amz-content-sha256", "x-amz-date"}, "UNSIGNED-PAYLOAD", false)
+	if err != nil {
+		t.Fatalf("buildCanonicalRequest failed: %v", err)
+	}
+
+	lines := strings.Split(canonical, "\n")
+	if len(lines) < 2 {
+		t.Fatalf("canonical request has unexpected format: %q", canonical)
+	}
+	wantPath := "/test-bucket/jsp-data-raw/year%3D2026/month%3D03/day%3D12/vehicle_positions.parquet"
+	if lines[1] != wantPath {
+		t.Fatalf("unexpected canonical path line: got %q want %q", lines[1], wantPath)
+	}
+}

cmd/admin.go

@@ -15,7 +15,7 @@ import (
 )
 
 const (
-	defaultAdminEndpoint = "http://localhost:3000"
+	defaultAdminEndpoint = "http://localhost:2600"
 	defaultAdminRegion   = "us-east-1"
 )
 
@@ -48,6 +48,7 @@ func newAdminCommand(build BuildInfo) *cobra.Command {
 
 	cmd.AddCommand(newAdminUserCommand(opts))
 	cmd.AddCommand(newAdminDiagCommand(opts, build))
+	cmd.AddCommand(newAdminSnapshotCommand(opts))
 	return cmd
 }
 
@@ -107,7 +108,7 @@ func endpointFromServerConfig(address string, port int) string {
 		host = "localhost"
 	}
 	if port <= 0 || port > 65535 {
-		port = 3000
+		port = 2600
 	}
 	return "http://" + net.JoinHostPort(host, strconv.Itoa(port))
 }

cmd/admin_snapshot.go

@@ -0,0 +1,728 @@
+package cmd
+
+import (
+	"archive/tar"
+	"compress/gzip"
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	bolt "go.etcd.io/bbolt"
+
+	"github.com/spf13/cobra"
+)
+
+const (
+	snapshotManifestPath = ".fs-snapshot/manifest.json"
+	snapshotFormat       = 1
+)
+
+type snapshotFileEntry struct {
+	Path   string `json:"path"`
+	Size   int64  `json:"size"`
+	SHA256 string `json:"sha256"`
+}
+
+type snapshotManifest struct {
+	FormatVersion int                 `json:"formatVersion"`
+	CreatedAt     string              `json:"createdAt"`
+	SourcePath    string              `json:"sourcePath"`
+	Files         []snapshotFileEntry `json:"files"`
+}
+
+type snapshotSummary struct {
+	SnapshotFile string `json:"snapshotFile"`
+	CreatedAt    string `json:"createdAt"`
+	SourcePath   string `json:"sourcePath"`
+	FileCount    int    `json:"fileCount"`
+	TotalBytes   int64  `json:"totalBytes"`
+}
+
+func newAdminSnapshotCommand(opts *adminOptions) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "snapshot",
+		Short: "Offline snapshot and restore utilities",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return cmd.Help()
+		},
+	}
+	cmd.AddCommand(newAdminSnapshotCreateCommand(opts))
+	cmd.AddCommand(newAdminSnapshotInspectCommand(opts))
+	cmd.AddCommand(newAdminSnapshotRestoreCommand(opts))
+	return cmd
+}
+
+func newAdminSnapshotCreateCommand(opts *adminOptions) *cobra.Command {
+	var dataPath string
+	var outFile string
+	cmd := &cobra.Command{
+		Use:   "create",
+		Short: "Create offline snapshot tarball (.tar.gz)",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			dataPath = strings.TrimSpace(dataPath)
+			outFile = strings.TrimSpace(outFile)
+			if dataPath == "" {
+				return usageError("fs admin snapshot create --data-path <path> --out <snapshot.tar.gz>", "--data-path is required")
+			}
+			if outFile == "" {
+				return usageError("fs admin snapshot create --data-path <path> --out <snapshot.tar.gz>", "--out is required")
+			}
+
+			result, err := createSnapshotArchive(context.Background(), dataPath, outFile)
+			if err != nil {
+				return err
+			}
+			if opts.JSON {
+				return writeJSON(cmd.OutOrStdout(), result)
+			}
+			_, err = fmt.Fprintf(cmd.OutOrStdout(), "snapshot created: %s (files=%d bytes=%d)\n", result.SnapshotFile, result.FileCount, result.TotalBytes)
+			return err
+		},
+	}
+	cmd.Flags().StringVar(&dataPath, "data-path", "", "Source data path (must contain metadata.db)")
+	cmd.Flags().StringVar(&outFile, "out", "", "Output snapshot file path (.tar.gz)")
+	return cmd
+}
+
+func newAdminSnapshotInspectCommand(opts *adminOptions) *cobra.Command {
+	var filePath string
+	cmd := &cobra.Command{
+		Use:   "inspect",
+		Short: "Inspect and verify snapshot archive integrity",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			filePath = strings.TrimSpace(filePath)
+			if filePath == "" {
+				return usageError("fs admin snapshot inspect --file <snapshot.tar.gz>", "--file is required")
+			}
+
+			manifest, summary, err := inspectSnapshotArchive(filePath)
+			if err != nil {
+				return err
+			}
+			if opts.JSON {
+				return writeJSON(cmd.OutOrStdout(), map[string]any{
+					"summary":  summary,
+					"manifest": manifest,
+				})
+			}
+			_, err = fmt.Fprintf(
+				cmd.OutOrStdout(),
+				"snapshot ok: %s\ncreated_at=%s source=%s files=%d bytes=%d\n",
+				summary.SnapshotFile,
+				summary.CreatedAt,
+				summary.SourcePath,
+				summary.FileCount,
+				summary.TotalBytes,
+			)
+			return err
+		},
+	}
+	cmd.Flags().StringVar(&filePath, "file", "", "Snapshot file path (.tar.gz)")
+	return cmd
+}
+
+func newAdminSnapshotRestoreCommand(opts *adminOptions) *cobra.Command {
+	var filePath string
+	var dataPath string
+	var force bool
+	cmd := &cobra.Command{
+		Use:   "restore",
+		Short: "Restore snapshot into a data path (offline only)",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			filePath = strings.TrimSpace(filePath)
+			dataPath = strings.TrimSpace(dataPath)
+			if filePath == "" {
+				return usageError("fs admin snapshot restore --file <snapshot.tar.gz> --data-path <path> [--force]", "--file is required")
+			}
+			if dataPath == "" {
+				return usageError("fs admin snapshot restore --file <snapshot.tar.gz> --data-path <path> [--force]", "--data-path is required")
+			}
+
+			result, err := restoreSnapshotArchive(context.Background(), filePath, dataPath, force)
+			if err != nil {
+				return err
+			}
+			if opts.JSON {
+				return writeJSON(cmd.OutOrStdout(), result)
+			}
+			_, err = fmt.Fprintf(
+				cmd.OutOrStdout(),
+				"snapshot restored to %s (files=%d bytes=%d)\n",
+				result.SourcePath,
+				result.FileCount,
+				result.TotalBytes,
+			)
+			return err
+		},
+	}
+	cmd.Flags().StringVar(&filePath, "file", "", "Snapshot file path (.tar.gz)")
+	cmd.Flags().StringVar(&dataPath, "data-path", "", "Destination data path")
+	cmd.Flags().BoolVar(&force, "force", false, "Overwrite destination data path if it exists")
+	return cmd
+}
+
+func createSnapshotArchive(ctx context.Context, dataPath, outFile string) (*snapshotSummary, error) {
+	_ = ctx
+	sourceAbs, err := filepath.Abs(filepath.Clean(dataPath))
+	if err != nil {
+		return nil, err
+	}
+	outAbs, err := filepath.Abs(filepath.Clean(outFile))
+	if err != nil {
+		return nil, err
+	}
+	if isPathWithin(sourceAbs, outAbs) {
+		return nil, errors.New("output file cannot be inside --data-path")
+	}
+
+	info, err := os.Stat(sourceAbs)
+	if err != nil {
+		return nil, err
+	}
+	if !info.IsDir() {
+		return nil, fmt.Errorf("data path %q is not a directory", sourceAbs)
+	}
+	if err := ensureMetadataExists(sourceAbs); err != nil {
+		return nil, err
+	}
+	if err := ensureDataPathOffline(sourceAbs); err != nil {
+		return nil, err
+	}
+
+	manifest, totalBytes, err := buildSnapshotManifest(sourceAbs)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := os.MkdirAll(filepath.Dir(outAbs), 0o755); err != nil {
+		return nil, err
+	}
+	tmpPath := outAbs + ".tmp-" + strconvNowNano()
+	file, err := os.OpenFile(tmpPath, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0o600)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		_ = file.Close()
+	}()
+
+	gzw := gzip.NewWriter(file)
+	tw := tar.NewWriter(gzw)
+	if err := writeManifestToTar(tw, manifest); err != nil {
+		_ = tw.Close()
+		_ = gzw.Close()
+		_ = os.Remove(tmpPath)
+		return nil, err
+	}
+
+	for _, entry := range manifest.Files {
+		absPath := filepath.Join(sourceAbs, filepath.FromSlash(entry.Path))
+		if err := writeFileToTar(tw, absPath, entry.Path); err != nil {
+			_ = tw.Close()
+			_ = gzw.Close()
+			_ = os.Remove(tmpPath)
+			return nil, err
+		}
+	}
+
+	if err := tw.Close(); err != nil {
+		_ = gzw.Close()
+		_ = os.Remove(tmpPath)
+		return nil, err
+	}
+	if err := gzw.Close(); err != nil {
+		_ = os.Remove(tmpPath)
+		return nil, err
+	}
+	if err := file.Sync(); err != nil {
+		_ = os.Remove(tmpPath)
+		return nil, err
+	}
+	if err := file.Close(); err != nil {
+		_ = os.Remove(tmpPath)
+		return nil, err
+	}
+	if err := os.Rename(tmpPath, outAbs); err != nil {
+		_ = os.Remove(tmpPath)
+		return nil, err
+	}
+	if err := syncDir(filepath.Dir(outAbs)); err != nil {
+		return nil, err
+	}
+
+	return &snapshotSummary{
+		SnapshotFile: outAbs,
+		CreatedAt:    manifest.CreatedAt,
+		SourcePath:   sourceAbs,
+		FileCount:    len(manifest.Files),
+		TotalBytes:   totalBytes,
+	}, nil
+}
+
+func inspectSnapshotArchive(filePath string) (*snapshotManifest, *snapshotSummary, error) {
+	fileAbs, err := filepath.Abs(filepath.Clean(filePath))
+	if err != nil {
+		return nil, nil, err
+	}
+	manifest, actual, err := readSnapshotArchive(fileAbs)
+	if err != nil {
+		return nil, nil, err
+	}
+	expected := map[string]snapshotFileEntry{}
+	var totalBytes int64
+	for _, entry := range manifest.Files {
+		expected[entry.Path] = entry
+		totalBytes += entry.Size
+	}
+	if len(expected) != len(actual) {
+		return nil, nil, fmt.Errorf("snapshot validation failed: expected %d files, got %d", len(expected), len(actual))
+	}
+	for path, exp := range expected {
+		got, ok := actual[path]
+		if !ok {
+			return nil, nil, fmt.Errorf("snapshot validation failed: missing file %s", path)
+		}
+		if got.Size != exp.Size || got.SHA256 != exp.SHA256 {
+			return nil, nil, fmt.Errorf("snapshot validation failed: checksum mismatch for %s", path)
+		}
+	}
+
+	return manifest, &snapshotSummary{
+		SnapshotFile: fileAbs,
+		CreatedAt:    manifest.CreatedAt,
+		SourcePath:   manifest.SourcePath,
+		FileCount:    len(manifest.Files),
+		TotalBytes:   totalBytes,
+	}, nil
+}
+
+func restoreSnapshotArchive(ctx context.Context, filePath, destinationPath string, force bool) (*snapshotSummary, error) {
+	_ = ctx
+	manifest, summary, err := inspectSnapshotArchive(filePath)
+	if err != nil {
+		return nil, err
+	}
+
+	destAbs, err := filepath.Abs(filepath.Clean(destinationPath))
+	if err != nil {
+		return nil, err
+	}
+
+	if fi, statErr := os.Stat(destAbs); statErr == nil && fi.IsDir() {
+		if err := ensureDataPathOffline(destAbs); err != nil {
+			return nil, err
+		}
+		entries, err := os.ReadDir(destAbs)
+		if err == nil && len(entries) > 0 && !force {
+			return nil, errors.New("destination data path is not empty; use --force to overwrite")
+		}
+	}
+
+	parent := filepath.Dir(destAbs)
+	if err := os.MkdirAll(parent, 0o755); err != nil {
+		return nil, err
+	}
+	stage := filepath.Join(parent, "."+filepath.Base(destAbs)+".restore-"+strconvNowNano())
+	if err := os.MkdirAll(stage, 0o755); err != nil {
+		return nil, err
+	}
+	cleanupStage := true
+	defer func() {
+		if cleanupStage {
+			_ = os.RemoveAll(stage)
+		}
+	}()
+
+	if err := extractSnapshotArchive(filePath, stage, manifest); err != nil {
+		return nil, err
+	}
+	if err := syncDir(stage); err != nil {
+		return nil, err
+	}
+
+	if _, err := os.Stat(destAbs); err == nil {
+		if !force {
+			return nil, errors.New("destination data path exists; use --force to overwrite")
+		}
+		if err := os.RemoveAll(destAbs); err != nil {
+			return nil, err
+		}
+	}
+
+	if err := os.Rename(stage, destAbs); err != nil {
+		return nil, err
+	}
+	if err := syncDir(parent); err != nil {
+		return nil, err
+	}
+	cleanupStage = false
+
+	summary.SourcePath = destAbs
+	return summary, nil
+}
+
+func ensureMetadataExists(dataPath string) error {
+	dbPath := filepath.Join(dataPath, "metadata.db")
+	info, err := os.Stat(dbPath)
+	if err != nil {
+		return fmt.Errorf("metadata.db not found in %s", dataPath)
+	}
+	if !info.Mode().IsRegular() {
+		return fmt.Errorf("metadata.db in %s is not a regular file", dataPath)
+	}
+	return nil
+}
+
+func ensureDataPathOffline(dataPath string) error {
+	dbPath := filepath.Join(dataPath, "metadata.db")
+	if _, err := os.Stat(dbPath); err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return nil
+		}
+		return err
+	}
+	db, err := bolt.Open(dbPath, 0o600, &bolt.Options{
+		Timeout:  100 * time.Millisecond,
+		ReadOnly: true,
+	})
+	if err != nil {
+		return fmt.Errorf("data path appears in use (metadata.db locked): %w", err)
+	}
+	return db.Close()
+}
+
+func buildSnapshotManifest(dataPath string) (*snapshotManifest, int64, error) {
+	entries := make([]snapshotFileEntry, 0, 128)
+	var totalBytes int64
+	err := filepath.WalkDir(dataPath, func(path string, d fs.DirEntry, walkErr error) error {
+		if walkErr != nil {
+			return walkErr
+		}
+		if d.IsDir() {
+			return nil
+		}
+		info, err := d.Info()
+		if err != nil {
+			return err
+		}
+		if !info.Mode().IsRegular() {
+			return nil
+		}
+
+		rel, err := filepath.Rel(dataPath, path)
+		if err != nil {
+			return err
+		}
+		rel = filepath.ToSlash(filepath.Clean(rel))
+		if rel == "." || rel == "" {
+			return nil
+		}
+
+		sum, err := sha256File(path)
+		if err != nil {
+			return err
+		}
+		totalBytes += info.Size()
+		entries = append(entries, snapshotFileEntry{
+			Path:   rel,
+			Size:   info.Size(),
+			SHA256: sum,
+		})
+		return nil
+	})
+	if err != nil {
+		return nil, 0, err
+	}
+	if len(entries) == 0 {
+		return nil, 0, errors.New("data path contains no regular files to snapshot")
+	}
+
+	return &snapshotManifest{
+		FormatVersion: snapshotFormat,
+		CreatedAt:     time.Now().UTC().Format(time.RFC3339Nano),
+		SourcePath:    dataPath,
+		Files:         entries,
+	}, totalBytes, nil
+}
+
+func writeManifestToTar(tw *tar.Writer, manifest *snapshotManifest) error {
+	if tw == nil || manifest == nil {
+		return errors.New("invalid manifest writer input")
+	}
+	payload, err := json.Marshal(manifest)
+	if err != nil {
+		return err
+	}
+	header := &tar.Header{
+		Name:    snapshotManifestPath,
+		Mode:    0o600,
+		Size:    int64(len(payload)),
+		ModTime: time.Now(),
+	}
+	if err := tw.WriteHeader(header); err != nil {
+		return err
+	}
+	_, err = tw.Write(payload)
+	return err
+}
+
+func writeFileToTar(tw *tar.Writer, absPath, relPath string) error {
+	file, err := os.Open(absPath)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	info, err := file.Stat()
+	if err != nil {
+		return err
+	}
+	header := &tar.Header{
+		Name:    relPath,
+		Mode:    int64(info.Mode().Perm()),
+		Size:    info.Size(),
+		ModTime: info.ModTime(),
+	}
+	if err := tw.WriteHeader(header); err != nil {
+		return err
+	}
+	_, err = io.Copy(tw, file)
+	return err
+}
+
+func readSnapshotArchive(filePath string) (*snapshotManifest, map[string]snapshotFileEntry, error) {
+	file, err := os.Open(filePath)
+	if err != nil {
+		return nil, nil, err
+	}
+	defer file.Close()
+
+	gzr, err := gzip.NewReader(file)
+	if err != nil {
+		return nil, nil, err
+	}
+	defer gzr.Close()
+
+	tr := tar.NewReader(gzr)
+	actual := make(map[string]snapshotFileEntry)
+	var manifest *snapshotManifest
+
+	for {
+		header, err := tr.Next()
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		if err != nil {
+			return nil, nil, err
+		}
+
+		name, err := cleanArchivePath(header.Name)
+		if err != nil {
+			return nil, nil, err
+		}
+		if header.Typeflag == tar.TypeDir {
+			continue
+		}
+		if header.Typeflag != tar.TypeReg && header.Typeflag != tar.TypeRegA {
+			return nil, nil, fmt.Errorf("unsupported tar entry type for %s", name)
+		}
+
+		if name == snapshotManifestPath {
+			raw, err := io.ReadAll(tr)
+			if err != nil {
+				return nil, nil, err
+			}
+			current := &snapshotManifest{}
+			if err := json.Unmarshal(raw, current); err != nil {
+				return nil, nil, err
+			}
+			manifest = current
+			continue
+		}
+
+		size, hashHex, err := digestReader(tr)
+		if err != nil {
+			return nil, nil, err
+		}
+		actual[name] = snapshotFileEntry{
+			Path:   name,
+			Size:   size,
+			SHA256: hashHex,
+		}
+	}
+
+	if manifest == nil {
+		return nil, nil, errors.New("snapshot manifest.json not found")
+	}
+	if manifest.FormatVersion != snapshotFormat {
+		return nil, nil, fmt.Errorf("unsupported snapshot format version %d", manifest.FormatVersion)
+	}
+	return manifest, actual, nil
+}
+
+func extractSnapshotArchive(filePath, destination string, manifest *snapshotManifest) error {
+	expected := make(map[string]snapshotFileEntry, len(manifest.Files))
+	for _, entry := range manifest.Files {
+		expected[entry.Path] = entry
+	}
+	seen := make(map[string]struct{}, len(expected))
+
+	file, err := os.Open(filePath)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	gzr, err := gzip.NewReader(file)
+	if err != nil {
+		return err
+	}
+	defer gzr.Close()
+
+	tr := tar.NewReader(gzr)
+	for {
+		header, err := tr.Next()
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		if err != nil {
+			return err
+		}
+		name, err := cleanArchivePath(header.Name)
+		if err != nil {
+			return err
+		}
+		if name == snapshotManifestPath {
+			if _, err := io.Copy(io.Discard, tr); err != nil {
+				return err
+			}
+			continue
+		}
+		if header.Typeflag == tar.TypeDir {
+			continue
+		}
+		if header.Typeflag != tar.TypeReg && header.Typeflag != tar.TypeRegA {
+			return fmt.Errorf("unsupported tar entry type for %s", name)
+		}
+
+		exp, ok := expected[name]
+		if !ok {
+			return fmt.Errorf("snapshot contains unexpected file %s", name)
+		}
+		targetPath := filepath.Join(destination, filepath.FromSlash(name))
+		if !isPathWithin(destination, targetPath) {
+			return fmt.Errorf("invalid archive path %s", name)
+		}
+
+		if err := os.MkdirAll(filepath.Dir(targetPath), 0o755); err != nil {
+			return err
+		}
+		out, err := os.OpenFile(targetPath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, os.FileMode(header.Mode)&0o777)
+		if err != nil {
+			return err
+		}
+
+		hasher := sha256.New()
+		written, copyErr := io.Copy(io.MultiWriter(out, hasher), tr)
+		syncErr := out.Sync()
+		closeErr := out.Close()
+		if copyErr != nil {
+			return copyErr
+		}
+		if syncErr != nil {
+			return syncErr
+		}
+		if closeErr != nil {
+			return closeErr
+		}
+		if err := syncDir(filepath.Dir(targetPath)); err != nil {
+			return err
+		}
+
+		sum := hex.EncodeToString(hasher.Sum(nil))
+		if written != exp.Size || sum != exp.SHA256 {
+			return fmt.Errorf("checksum mismatch while extracting %s", name)
+		}
+		seen[name] = struct{}{}
+	}
+
+	if len(seen) != len(expected) {
+		return fmt.Errorf("restore validation failed: extracted %d files, expected %d", len(seen), len(expected))
+	}
+	for path := range expected {
+		if _, ok := seen[path]; !ok {
+			return fmt.Errorf("restore validation failed: missing file %s", path)
+		}
+	}
+	return nil
+}
+
+func cleanArchivePath(name string) (string, error) {
+	name = strings.TrimSpace(name)
+	if name == "" {
+		return "", errors.New("empty archive path")
+	}
+	name = filepath.ToSlash(filepath.Clean(name))
+	if strings.HasPrefix(name, "/") || strings.HasPrefix(name, "../") || strings.Contains(name, "/../") || name == ".." {
+		return "", fmt.Errorf("unsafe archive path %q", name)
+	}
+	return name, nil
+}
+
+func digestReader(r io.Reader) (int64, string, error) {
+	hasher := sha256.New()
+	n, err := io.Copy(hasher, r)
+	if err != nil {
+		return 0, "", err
+	}
+	return n, hex.EncodeToString(hasher.Sum(nil)), nil
+}
+
+func sha256File(path string) (string, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+	return sha256FromReader(file)
+}
+
+func sha256FromReader(reader io.Reader) (string, error) {
+	hasher := sha256.New()
+	if _, err := io.Copy(hasher, reader); err != nil {
+		return "", err
+	}
+	return hex.EncodeToString(hasher.Sum(nil)), nil
+}
+
+func isPathWithin(base, candidate string) bool {
+	base = filepath.Clean(base)
+	candidate = filepath.Clean(candidate)
+	rel, err := filepath.Rel(base, candidate)
+	if err != nil {
+		return false
+	}
+	return rel == "." || (rel != ".." && !strings.HasPrefix(rel, ".."+string(filepath.Separator)))
+}
+
+func syncDir(path string) error {
+	dir, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer dir.Close()
+	return dir.Sync()
+}
+
+func strconvNowNano() string {
+	return fmt.Sprintf("%d", time.Now().UnixNano())
+}

cmd/admin_snapshot_test.go

@@ -0,0 +1,240 @@
+package cmd
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	bolt "go.etcd.io/bbolt"
+)
+
+type snapshotArchiveEntry struct {
+	Path string
+	Data []byte
+}
+
+func TestInspectSnapshotArchiveRejectsUnsafePath(t *testing.T) {
+	t.Parallel()
+
+	archive := filepath.Join(t.TempDir(), "bad.tar.gz")
+	manifest := manifestForEntries([]snapshotArchiveEntry{
+		{Path: "metadata.db", Data: []byte("db")},
+	})
+	err := writeSnapshotArchiveForTest(archive, manifest, []snapshotArchiveEntry{
+		{Path: "../escape", Data: []byte("oops")},
+	}, true)
+	if err != nil {
+		t.Fatalf("write test archive: %v", err)
+	}
+
+	_, _, err = inspectSnapshotArchive(archive)
+	if err == nil || !strings.Contains(err.Error(), "unsafe archive path") {
+		t.Fatalf("expected unsafe archive path error, got %v", err)
+	}
+}
+
+func TestInspectSnapshotArchiveChecksumMismatch(t *testing.T) {
+	t.Parallel()
+
+	archive := filepath.Join(t.TempDir(), "mismatch.tar.gz")
+	manifest := manifestForEntries([]snapshotArchiveEntry{
+		{Path: "chunks/c1", Data: []byte("good")},
+	})
+	err := writeSnapshotArchiveForTest(archive, manifest, []snapshotArchiveEntry{
+		{Path: "chunks/c1", Data: []byte("bad")},
+	}, true)
+	if err != nil {
+		t.Fatalf("write test archive: %v", err)
+	}
+
+	_, _, err = inspectSnapshotArchive(archive)
+	if err == nil || !strings.Contains(err.Error(), "checksum mismatch") {
+		t.Fatalf("expected checksum mismatch error, got %v", err)
+	}
+}
+
+func TestInspectSnapshotArchiveMissingManifest(t *testing.T) {
+	t.Parallel()
+
+	archive := filepath.Join(t.TempDir(), "no-manifest.tar.gz")
+	err := writeSnapshotArchiveForTest(archive, nil, []snapshotArchiveEntry{
+		{Path: "chunks/c1", Data: []byte("x")},
+	}, false)
+	if err != nil {
+		t.Fatalf("write test archive: %v", err)
+	}
+
+	_, _, err = inspectSnapshotArchive(archive)
+	if err == nil || !strings.Contains(err.Error(), "manifest.json not found") {
+		t.Fatalf("expected missing manifest error, got %v", err)
+	}
+}
+
+func TestInspectSnapshotArchiveUnsupportedFormat(t *testing.T) {
+	t.Parallel()
+
+	archive := filepath.Join(t.TempDir(), "unsupported-format.tar.gz")
+	manifest := manifestForEntries([]snapshotArchiveEntry{
+		{Path: "chunks/c1", Data: []byte("x")},
+	})
+	manifest.FormatVersion = 99
+	err := writeSnapshotArchiveForTest(archive, manifest, []snapshotArchiveEntry{
+		{Path: "chunks/c1", Data: []byte("x")},
+	}, true)
+	if err != nil {
+		t.Fatalf("write test archive: %v", err)
+	}
+
+	_, _, err = inspectSnapshotArchive(archive)
+	if err == nil || !strings.Contains(err.Error(), "unsupported snapshot format version") {
+		t.Fatalf("expected unsupported format error, got %v", err)
+	}
+}
+
+func TestRestoreSnapshotArchiveDestinationBehavior(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	archive := filepath.Join(root, "ok.tar.gz")
+	destination := filepath.Join(root, "dst")
+
+	entries := []snapshotArchiveEntry{
+		{Path: "metadata.db", Data: []byte("db-bytes")},
+		{Path: "chunks/c1", Data: []byte("chunk-1")},
+	}
+	manifest := manifestForEntries(entries)
+	if err := writeSnapshotArchiveForTest(archive, manifest, entries, true); err != nil {
+		t.Fatalf("write test archive: %v", err)
+	}
+
+	if err := os.MkdirAll(destination, 0o755); err != nil {
+		t.Fatalf("mkdir destination: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(destination, "old.txt"), []byte("old"), 0o600); err != nil {
+		t.Fatalf("seed destination: %v", err)
+	}
+
+	if _, err := restoreSnapshotArchive(context.Background(), archive, destination, false); err == nil || !strings.Contains(err.Error(), "not empty") {
+		t.Fatalf("expected non-empty destination error, got %v", err)
+	}
+
+	if _, err := restoreSnapshotArchive(context.Background(), archive, destination, true); err != nil {
+		t.Fatalf("restore with force: %v", err)
+	}
+
+	if _, err := os.Stat(filepath.Join(destination, "old.txt")); !os.IsNotExist(err) {
+		t.Fatalf("expected old file to be removed, stat err=%v", err)
+	}
+	got, err := os.ReadFile(filepath.Join(destination, "chunks/c1"))
+	if err != nil {
+		t.Fatalf("read restored chunk: %v", err)
+	}
+	if string(got) != "chunk-1" {
+		t.Fatalf("restored chunk mismatch: got %q", string(got))
+	}
+}
+
+func TestCreateSnapshotArchiveRejectsOutputInsideDataPath(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(root, "chunks"), 0o755); err != nil {
+		t.Fatalf("mkdir chunks: %v", err)
+	}
+	if err := createBoltDBForTest(filepath.Join(root, "metadata.db")); err != nil {
+		t.Fatalf("create metadata db: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "chunks/c1"), []byte("x"), 0o600); err != nil {
+		t.Fatalf("write chunk: %v", err)
+	}
+
+	out := filepath.Join(root, "inside.tar.gz")
+	if _, err := createSnapshotArchive(context.Background(), root, out); err == nil || !strings.Contains(err.Error(), "cannot be inside") {
+		t.Fatalf("expected output-inside-data-path error, got %v", err)
+	}
+}
+
+func writeSnapshotArchiveForTest(path string, manifest *snapshotManifest, entries []snapshotArchiveEntry, includeManifest bool) error {
+	file, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	gzw := gzip.NewWriter(file)
+	defer gzw.Close()
+	tw := tar.NewWriter(gzw)
+	defer tw.Close()
+
+	if includeManifest {
+		raw, err := json.Marshal(manifest)
+		if err != nil {
+			return err
+		}
+		if err := writeTarEntry(tw, snapshotManifestPath, raw); err != nil {
+			return err
+		}
+	}
+	for _, entry := range entries {
+		if err := writeTarEntry(tw, entry.Path, entry.Data); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func writeTarEntry(tw *tar.Writer, name string, data []byte) error {
+	header := &tar.Header{
+		Name: name,
+		Mode: 0o600,
+		Size: int64(len(data)),
+	}
+	if err := tw.WriteHeader(header); err != nil {
+		return err
+	}
+	_, err := ioCopyBytes(tw, data)
+	return err
+}
+
+func manifestForEntries(entries []snapshotArchiveEntry) *snapshotManifest {
+	files := make([]snapshotFileEntry, 0, len(entries))
+	for _, entry := range entries {
+		sum := sha256.Sum256(entry.Data)
+		files = append(files, snapshotFileEntry{
+			Path:   filepath.ToSlash(filepath.Clean(entry.Path)),
+			Size:   int64(len(entry.Data)),
+			SHA256: hex.EncodeToString(sum[:]),
+		})
+	}
+	return &snapshotManifest{
+		FormatVersion: snapshotFormat,
+		CreatedAt:     "2026-03-11T00:00:00Z",
+		SourcePath:    "/tmp/source",
+		Files:         files,
+	}
+}
+
+func createBoltDBForTest(path string) error {
+	db, err := bolt.Open(path, 0o600, nil)
+	if err != nil {
+		return err
+	}
+	defer db.Close()
+	return db.Update(func(tx *bolt.Tx) error {
+		_, err := tx.CreateBucketIfNotExists([]byte("x"))
+		return err
+	})
+}
+
+func ioCopyBytes(w *tar.Writer, data []byte) (int64, error) {
+	n, err := bytes.NewReader(data).WriteTo(w)
+	return n, err
+}

cmd/admin_user.go

@@ -22,6 +22,7 @@ func newAdminUserCommand(opts *adminOptions) *cobra.Command {
 	cmd.AddCommand(newAdminUserDeleteCommand(opts))
 	cmd.AddCommand(newAdminUserSetStatusCommand(opts))
 	cmd.AddCommand(newAdminUserSetRoleCommand(opts))
+	cmd.AddCommand(newAdminUserRemoveRoleCommand(opts))
 	return cmd
 }
 
@@ -253,6 +254,68 @@ func newAdminUserSetRoleCommand(opts *adminOptions) *cobra.Command {
 	return cmd
 }
 
+func newAdminUserRemoveRoleCommand(opts *adminOptions) *cobra.Command {
+	var (
+		role   string
+		bucket string
+		prefix string
+	)
+	cmd := &cobra.Command{
+		Use:   "remove-role <access-key-id>",
+		Short: "Remove one role policy statement from user",
+		Args:  requireAccessKeyArg("fs admin user remove-role <access-key-id> --role admin|readwrite|readonly [--bucket <name>] [--prefix <path>]"),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			policy, err := buildPolicyFromRole(rolePolicyOptions{
+				Role:   role,
+				Bucket: bucket,
+				Prefix: prefix,
+			})
+			if err != nil {
+				return usageError("fs admin user remove-role <access-key-id> --role admin|readwrite|readonly [--bucket <name>] [--prefix <path>]", err.Error())
+			}
+			if len(policy.Statements) == 0 {
+				return usageError("fs admin user remove-role <access-key-id> --role admin|readwrite|readonly [--bucket <name>] [--prefix <path>]", "no statement to remove")
+			}
+
+			client, err := newAdminAPIClient(opts, true)
+			if err != nil {
+				return err
+			}
+
+			existing, err := client.GetUser(context.Background(), args[0])
+			if err != nil {
+				return err
+			}
+			if existing.Policy == nil || len(existing.Policy.Statements) == 0 {
+				return fmt.Errorf("user %q has no policy statements", args[0])
+			}
+
+			target := policy.Statements[0]
+			nextPolicy, removed := removePolicyStatements(existing.Policy, target)
+			if removed == 0 {
+				return fmt.Errorf("no matching statement found for role=%s bucket=%s prefix=%s", role, bucket, prefix)
+			}
+			if len(nextPolicy.Statements) == 0 {
+				return fmt.Errorf("cannot remove the last policy statement; add another role first or use set-role --replace")
+			}
+
+			out, err := client.SetUserPolicy(context.Background(), args[0], nextPolicy)
+			if err != nil {
+				return err
+			}
+			if opts.JSON {
+				return writeJSON(cmd.OutOrStdout(), out)
+			}
+			return writeUserTable(cmd.OutOrStdout(), out, false)
+		},
+	}
+
+	cmd.Flags().StringVar(&role, "role", "readwrite", "Role: admin|readwrite|readonly")
+	cmd.Flags().StringVar(&bucket, "bucket", "*", "Bucket scope, defaults to *")
+	cmd.Flags().StringVar(&prefix, "prefix", "*", "Prefix scope, defaults to *")
+	return cmd
+}
+
 func mergePolicyStatements(existing *adminPolicy, addition adminPolicy) adminPolicy {
 	merged := adminPolicy{}
 	if existing != nil {
@@ -289,6 +352,25 @@ func policyStatementsEqual(a, b adminPolicyStatement) bool {
 	return true
 }
 
+func removePolicyStatements(existing *adminPolicy, target adminPolicyStatement) (adminPolicy, int) {
+	out := adminPolicy{}
+	if existing == nil {
+		return out, 0
+	}
+	out.Principal = existing.Principal
+	out.Statements = make([]adminPolicyStatement, 0, len(existing.Statements))
+
+	removed := 0
+	for _, stmt := range existing.Statements {
+		if policyStatementsEqual(stmt, target) {
+			removed++
+			continue
+		}
+		out.Statements = append(out.Statements, stmt)
+	}
+	return out, removed
+}
+
 func requireAccessKeyArg(usage string) cobra.PositionalArgs {
 	return func(cmd *cobra.Command, args []string) error {
 		if len(args) != 1 {

docs/s3-compatibility.md

@@ -32,12 +32,15 @@ This project is S3-compatible for a focused subset of operations.
 ### Authentication
 - AWS SigV4 header auth
 - AWS SigV4 presigned query auth
-- `aws-chunked` payload decode for streaming uploads
+- `aws-chunked` payload decode for unsigned streaming upload modes
+- SigV4 payload hash verification for fixed-size signed payloads
 
 ## Partially Implemented / Differences
 - Exact parity with AWS S3 error codes/headers is still evolving.
 - Some S3 edge-case behaviors may differ (especially uncommon query/header combinations).
 - Admin API is custom JSON (`/_admin/v1/*`).
+- Object and upload-part payloads are limited by `FS_MAX_OBJECT_UPLOAD_BYTES` (default 5 GiB).
+- Signed `aws-chunked` payload modes that require per-chunk signature verification are rejected until chunk-signature validation is implemented.
 
 ## Not Implemented (Current)
 - Bucket versioning

metadata/metadata.go

@@ -902,9 +902,6 @@ func (h *MetadataHandler) CleanupMultipartUploads(retention time.Duration) (int,
 			if err := json.Unmarshal(v, &upload); err != nil {
 				return err
 			}
-			if upload.State == "pending" {
-				return nil
-			}
 			createdAt, err := time.Parse(time.RFC3339, upload.CreatedAt)
 			if err != nil {
 				return nil

metadata/metadata_test.go

@@ -0,0 +1,99 @@
+package metadata
+
+import (
+	"errors"
+	"fs/models"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"go.etcd.io/bbolt"
+)
+
+func TestCleanupMultipartUploadsDeletesExpiredPendingUpload(t *testing.T) {
+	h := newTestMetadataHandler(t)
+	if err := h.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("CreateBucket: %v", err)
+	}
+	upload, err := h.CreateMultipartUpload("test-bucket", "object.txt")
+	if err != nil {
+		t.Fatalf("CreateMultipartUpload: %v", err)
+	}
+	if err := h.PutMultipartPart(upload.UploadID, models.UploadedPart{PartNumber: 1, ETag: "etag", Size: 4, Chunks: []string{"chunk-id"}}); err != nil {
+		t.Fatalf("PutMultipartPart: %v", err)
+	}
+	setMultipartUploadCreatedAt(t, h, upload.UploadID, time.Now().Add(-2*time.Hour))
+
+	cleaned, err := h.CleanupMultipartUploads(time.Hour)
+	if err != nil {
+		t.Fatalf("CleanupMultipartUploads: %v", err)
+	}
+	if cleaned != 1 {
+		t.Fatalf("cleaned = %d, want 1", cleaned)
+	}
+	if _, err := h.GetMultipartUpload(upload.UploadID); !errors.Is(err, ErrMultipartNotFound) {
+		t.Fatalf("GetMultipartUpload error = %v, want ErrMultipartNotFound", err)
+	}
+	if _, err := h.ListMultipartParts(upload.UploadID); !errors.Is(err, ErrMultipartNotFound) {
+		t.Fatalf("ListMultipartParts error = %v, want ErrMultipartNotFound", err)
+	}
+}
+
+func TestCleanupMultipartUploadsKeepsRecentPendingUpload(t *testing.T) {
+	h := newTestMetadataHandler(t)
+	if err := h.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("CreateBucket: %v", err)
+	}
+	upload, err := h.CreateMultipartUpload("test-bucket", "object.txt")
+	if err != nil {
+		t.Fatalf("CreateMultipartUpload: %v", err)
+	}
+
+	cleaned, err := h.CleanupMultipartUploads(time.Hour)
+	if err != nil {
+		t.Fatalf("CleanupMultipartUploads: %v", err)
+	}
+	if cleaned != 0 {
+		t.Fatalf("cleaned = %d, want 0", cleaned)
+	}
+	if _, err := h.GetMultipartUpload(upload.UploadID); err != nil {
+		t.Fatalf("recent upload should remain: %v", err)
+	}
+}
+
+func TestCleanupMultipartUploadsDisabledForNonPositiveRetention(t *testing.T) {
+	h := newTestMetadataHandler(t)
+	cleaned, err := h.CleanupMultipartUploads(0)
+	if err != nil {
+		t.Fatalf("CleanupMultipartUploads: %v", err)
+	}
+	if cleaned != 0 {
+		t.Fatalf("cleaned = %d, want 0", cleaned)
+	}
+}
+
+func newTestMetadataHandler(t *testing.T) *MetadataHandler {
+	t.Helper()
+	h, err := NewMetadataHandler(filepath.Join(t.TempDir(), "metadata.db"))
+	if err != nil {
+		t.Fatalf("NewMetadataHandler: %v", err)
+	}
+	t.Cleanup(func() {
+		_ = h.Close()
+	})
+	return h
+}
+
+func setMultipartUploadCreatedAt(t *testing.T, h *MetadataHandler, uploadID string, createdAt time.Time) {
+	t.Helper()
+	if err := h.update(func(tx *bbolt.Tx) error {
+		upload, uploadsBucket, err := getMultipartUploadFromTx(tx, uploadID)
+		if err != nil {
+			return err
+		}
+		upload.CreatedAt = createdAt.UTC().Format(time.RFC3339)
+		return putMultipartUpload(uploadsBucket, uploadID, upload)
+	}); err != nil {
+		t.Fatalf("set multipart created_at: %v", err)
+	}
+}

models/models.go

@@ -158,6 +158,13 @@ type CompleteMultipartUploadResult struct {
 	Location string   `xml:"Location,omitempty"`
 }
 
+type CopyObjectResult struct {
+	XMLName      xml.Name `xml:"CopyObjectResult"`
+	Xmlns        string   `xml:"xmlns,attr,omitempty"`
+	LastModified string   `xml:"LastModified"`
+	ETag         string   `xml:"ETag"`
+}
+
 type ListPartsResult struct {
 	XMLName  xml.Name   `xml:"ListPartsResult"`
 	Xmlns    string     `xml:"xmlns,attr"`

service/service.go

@@ -21,6 +21,7 @@ type ObjectService struct {
 	metadata           *metadata.MetadataHandler
 	blob               *storage.BlobStore
 	multipartRetention time.Duration
+	maxUploadSize      int64
 	gcMu               sync.RWMutex
 }
 
@@ -29,16 +30,24 @@ var (
 	ErrInvalidPartOrder       = errors.New("invalid multipart part order")
 	ErrInvalidCompleteRequest = errors.New("invalid complete multipart request")
 	ErrEntityTooSmall         = errors.New("multipart entity too small")
+	ErrEntityTooLarge         = errors.New("entity too large")
 )
 
-func NewObjectService(metadataHandler *metadata.MetadataHandler, blobHandler *storage.BlobStore, multipartRetention time.Duration) *ObjectService {
+const DefaultMaxUploadSize int64 = 5 * 1024 * 1024 * 1024
+
+func NewObjectService(metadataHandler *metadata.MetadataHandler, blobHandler *storage.BlobStore, multipartRetention time.Duration, maxUploadSize ...int64) *ObjectService {
 	if multipartRetention <= 0 {
 		multipartRetention = 24 * time.Hour
 	}
+	limit := DefaultMaxUploadSize
+	if len(maxUploadSize) > 0 {
+		limit = maxUploadSize[0]
+	}
 	return &ObjectService{
 		metadata:           metadataHandler,
 		blob:               blobHandler,
 		multipartRetention: multipartRetention,
+		maxUploadSize:      limit,
 	}
 }
 
@@ -74,7 +83,7 @@ func (s *ObjectService) PutObject(bucket, key, contentType string, input io.Read
 	unlock := s.acquireGCRLock()
 	defer unlock()
 
-	chunks, size, etag, err := s.blob.IngestStream(input)
+	chunks, size, etag, err := s.blob.IngestStream(s.limitUpload(input))
 	if err != nil {
 		return nil, err
 	}
@@ -104,6 +113,38 @@ func (s *ObjectService) PutObject(bucket, key, contentType string, input io.Read
 	return manifest, nil
 }
 
+func (s *ObjectService) CopyObject(srcBucket, srcKey, dstBucket, dstKey string) (*models.ObjectManifest, error) {
+	start := time.Now()
+	success := false
+	defer func() {
+		metrics.Default.ObserveService("copy_object", time.Since(start), success)
+	}()
+
+	unlock := s.acquireGCRLock()
+	defer unlock()
+
+	source, err := s.metadata.GetManifest(srcBucket, srcKey)
+	if err != nil {
+		return nil, err
+	}
+
+	manifest := &models.ObjectManifest{
+		Bucket:      dstBucket,
+		Key:         dstKey,
+		Size:        source.Size,
+		ContentType: source.ContentType,
+		ETag:        source.ETag,
+		Chunks:      append([]string(nil), source.Chunks...),
+		CreatedAt:   time.Now().Unix(),
+	}
+	if err := s.metadata.PutManifest(manifest); err != nil {
+		return nil, err
+	}
+
+	success = true
+	return manifest, nil
+}
+
 func (s *ObjectService) GetObject(bucket, key string) (io.ReadCloser, *models.ObjectManifest, error) {
 	start := time.Now()
 
@@ -126,7 +167,9 @@ func (s *ObjectService) GetObject(bucket, key string) (io.ReadCloser, *models.Ob
 		defer func() {
 			metrics.Default.ObserveService("get_object", time.Since(start), streamOK)
 		}()
-		defer metrics.Default.ObserveLockHold("gc_mu_read", time.Since(holdStart))
+		defer func() {
+			metrics.Default.ObserveLockHold("gc_mu_read", time.Since(holdStart))
+		}()
 		defer s.gcMu.RUnlock()
 		if err := s.blob.AssembleStream(manifest.Chunks, pw); err != nil {
 			_ = pw.CloseWithError(err)
@@ -279,7 +322,7 @@ func (s *ObjectService) UploadPart(bucket, key, uploadId string, partNumber int,
 	}
 
 	var uploadedPart models.UploadedPart
-	chunkIds, totalSize, etag, err := s.blob.IngestStream(input)
+	chunkIds, totalSize, etag, err := s.blob.IngestStream(s.limitUpload(input))
 	if err != nil {
 		return "", err
 	}
@@ -368,6 +411,9 @@ func (s *ObjectService) CompleteMultipartUpload(bucket, key, uploadID string, co
 		orderedParts = append(orderedParts, storedPart)
 		chunks = append(chunks, storedPart.Chunks...)
 		totalSize += storedPart.Size
+		if s.maxUploadSize > 0 && totalSize > s.maxUploadSize {
+			return nil, ErrEntityTooLarge
+		}
 	}
 
 	finalETag := buildMultipartETag(orderedParts)
@@ -403,6 +449,40 @@ func (s *ObjectService) AbortMultipartUpload(bucket, key, uploadID string) error
 	return s.metadata.AbortMultipartUpload(uploadID)
 }
 
+func (s *ObjectService) limitUpload(input io.Reader) io.Reader {
+	if s.maxUploadSize <= 0 || input == nil {
+		return input
+	}
+	return &maxBytesReader{inner: input, remaining: s.maxUploadSize}
+}
+
+type maxBytesReader struct {
+	inner     io.Reader
+	remaining int64
+	tooLarge  bool
+}
+
+func (r *maxBytesReader) Read(p []byte) (int, error) {
+	if r.tooLarge {
+		return 0, ErrEntityTooLarge
+	}
+	if r.remaining <= 0 {
+		var probe [1]byte
+		n, err := r.inner.Read(probe[:])
+		if n > 0 {
+			r.tooLarge = true
+			return 0, ErrEntityTooLarge
+		}
+		return 0, err
+	}
+	if int64(len(p)) > r.remaining {
+		p = p[:r.remaining]
+	}
+	n, err := r.inner.Read(p)
+	r.remaining -= int64(n)
+	return n, err
+}
+
 func normalizeETag(etag string) string {
 	return strings.Trim(etag, "\"")
 }
@@ -437,6 +517,12 @@ func (s *ObjectService) GarbageCollect() error {
 	unlock := s.acquireGCLock()
 	defer unlock()
 
+	var err error
+	cleanedUploads, err = s.metadata.CleanupMultipartUploads(s.multipartRetention)
+	if err != nil {
+		return err
+	}
+
 	referencedChunkSet, err := s.metadata.GetReferencedChunkSet()
 	if err != nil {
 		return err
@@ -460,11 +546,6 @@ func (s *ObjectService) GarbageCollect() error {
 		return err
 	}
 
-	cleanedUploads, err = s.metadata.CleanupMultipartUploads(s.multipartRetention)
-	if err != nil {
-		return err
-	}
-
 	slog.Info("garbage_collect_completed",
 		"referenced_chunks", len(referencedChunkSet),
 		"total_chunks", totalChunks,

service/upload_limit_test.go

@@ -0,0 +1,119 @@
+package service
+
+import (
+	"errors"
+	"fs/metadata"
+	"fs/storage"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestPutObjectRejectsOversizedUpload(t *testing.T) {
+	svc := newTestObjectService(t, 4)
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("CreateBucket: %v", err)
+	}
+
+	_, err := svc.PutObject("test-bucket", "too-large.txt", "text/plain", strings.NewReader("12345"))
+	if !errors.Is(err, ErrEntityTooLarge) {
+		t.Fatalf("PutObject error = %v, want ErrEntityTooLarge", err)
+	}
+	if _, err := svc.HeadObject("test-bucket", "too-large.txt"); !errors.Is(err, metadata.ErrObjectNotFound) {
+		t.Fatalf("HeadObject error = %v, want ErrObjectNotFound", err)
+	}
+}
+
+func TestPutObjectAllowsExactUploadLimit(t *testing.T) {
+	svc := newTestObjectService(t, 4)
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("CreateBucket: %v", err)
+	}
+
+	manifest, err := svc.PutObject("test-bucket", "exact.txt", "text/plain", strings.NewReader("1234"))
+	if err != nil {
+		t.Fatalf("PutObject: %v", err)
+	}
+	if manifest.Size != 4 {
+		t.Fatalf("manifest size = %d, want 4", manifest.Size)
+	}
+}
+
+func TestUploadPartRejectsOversizedUpload(t *testing.T) {
+	svc := newTestObjectService(t, 4)
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("CreateBucket: %v", err)
+	}
+	upload, err := svc.CreateMultipartUpload("test-bucket", "object.txt")
+	if err != nil {
+		t.Fatalf("CreateMultipartUpload: %v", err)
+	}
+
+	_, err = svc.UploadPart("test-bucket", "object.txt", upload.UploadID, 1, strings.NewReader("12345"))
+	if !errors.Is(err, ErrEntityTooLarge) {
+		t.Fatalf("UploadPart error = %v, want ErrEntityTooLarge", err)
+	}
+	parts, err := svc.ListMultipartParts("test-bucket", "object.txt", upload.UploadID)
+	if err != nil {
+		t.Fatalf("ListMultipartParts: %v", err)
+	}
+	if len(parts) != 0 {
+		t.Fatalf("stored parts = %d, want 0", len(parts))
+	}
+}
+
+func TestGarbageCollectRemovesExpiredPendingMultipartChunks(t *testing.T) {
+	svc := newTestObjectService(t, 1024)
+	svc.multipartRetention = time.Nanosecond
+	if err := svc.CreateBucket("test-bucket"); err != nil {
+		t.Fatalf("CreateBucket: %v", err)
+	}
+	upload, err := svc.CreateMultipartUpload("test-bucket", "object.txt")
+	if err != nil {
+		t.Fatalf("CreateMultipartUpload: %v", err)
+	}
+	if _, err := svc.UploadPart("test-bucket", "object.txt", upload.UploadID, 1, strings.NewReader("part-data")); err != nil {
+		t.Fatalf("UploadPart: %v", err)
+	}
+	chunks, err := svc.blob.ListChunks()
+	if err != nil {
+		t.Fatalf("ListChunks before GC: %v", err)
+	}
+	if len(chunks) == 0 {
+		t.Fatalf("expected uploaded part chunks")
+	}
+	time.Sleep(time.Millisecond)
+
+	if err := svc.GarbageCollect(); err != nil {
+		t.Fatalf("GarbageCollect: %v", err)
+	}
+	if _, err := svc.metadata.GetMultipartUpload(upload.UploadID); !errors.Is(err, metadata.ErrMultipartNotFound) {
+		t.Fatalf("GetMultipartUpload error = %v, want ErrMultipartNotFound", err)
+	}
+	chunks, err = svc.blob.ListChunks()
+	if err != nil {
+		t.Fatalf("ListChunks after GC: %v", err)
+	}
+	if len(chunks) != 0 {
+		t.Fatalf("chunks after GC = %d, want 0", len(chunks))
+	}
+}
+
+func newTestObjectService(t *testing.T, maxUploadSize int64) *ObjectService {
+	t.Helper()
+	root := t.TempDir()
+	md, err := metadata.NewMetadataHandler(filepath.Join(root, "metadata.db"))
+	if err != nil {
+		t.Fatalf("NewMetadataHandler: %v", err)
+	}
+	blob, err := storage.NewBlobStore(root, 4)
+	if err != nil {
+		t.Fatalf("NewBlobStore: %v", err)
+	}
+	svc := NewObjectService(md, blob, time.Hour, maxUploadSize)
+	t.Cleanup(func() {
+		_ = svc.Close()
+	})
+	return svc
+}

storage/blob.go

@@ -17,6 +17,8 @@ import (
 const blobRoot = "blobs"
 const maxChunkSize = 64 * 1024 * 1024
 
+var ErrChunkIntegrity = errors.New("chunk integrity check failed")
+
 type BlobStore struct {
 	dataRoot  string
 	chunkSize int
@@ -185,6 +187,11 @@ func (bs *BlobStore) GetBlob(chunkID string) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
+	chunkHash := sha256.Sum256(data)
+	actualChunkID := hex.EncodeToString(chunkHash[:])
+	if actualChunkID != chunkID {
+		return nil, fmt.Errorf("%w: expected %s, got %s", ErrChunkIntegrity, chunkID, actualChunkID)
+	}
 	size = int64(len(data))
 	success = true
 	return data, nil

storage/blob_test.go

@@ -0,0 +1,79 @@
+package storage
+
+import (
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestGetBlobDetectsCorruptedChunk(t *testing.T) {
+	root := t.TempDir()
+	bs, err := NewBlobStore(root, 4)
+	if err != nil {
+		t.Fatalf("new blob store: %v", err)
+	}
+
+	chunks, _, _, err := bs.IngestStream(strings.NewReader("good"))
+	if err != nil {
+		t.Fatalf("ingest: %v", err)
+	}
+	chunkID := chunks[0]
+	corruptChunk(t, root, chunkID, []byte("bad"))
+
+	got, err := bs.GetBlob(chunkID)
+	if !errors.Is(err, ErrChunkIntegrity) {
+		t.Fatalf("GetBlob error = %v, want ErrChunkIntegrity", err)
+	}
+	if got != nil {
+		t.Fatalf("GetBlob returned data for corrupted chunk: %q", got)
+	}
+}
+
+func TestAssembleStreamDetectsCorruptedChunk(t *testing.T) {
+	root := t.TempDir()
+	bs, err := NewBlobStore(root, 4)
+	if err != nil {
+		t.Fatalf("new blob store: %v", err)
+	}
+
+	chunks, _, _, err := bs.IngestStream(strings.NewReader("abcdefgh"))
+	if err != nil {
+		t.Fatalf("ingest: %v", err)
+	}
+	if len(chunks) != 2 {
+		t.Fatalf("chunk count = %d, want 2", len(chunks))
+	}
+	corruptChunk(t, root, chunks[1], []byte("corrupt"))
+
+	pr, pw := io.Pipe()
+	errCh := make(chan error, 1)
+	go func() {
+		err := bs.AssembleStream(chunks, pw)
+		if err != nil {
+			_ = pw.CloseWithError(err)
+		} else {
+			_ = pw.Close()
+		}
+		errCh <- err
+	}()
+
+	_, readErr := io.ReadAll(pr)
+	assembleErr := <-errCh
+	if !errors.Is(assembleErr, ErrChunkIntegrity) {
+		t.Fatalf("AssembleStream error = %v, want ErrChunkIntegrity", assembleErr)
+	}
+	if !errors.Is(readErr, ErrChunkIntegrity) {
+		t.Fatalf("pipe read error = %v, want ErrChunkIntegrity", readErr)
+	}
+}
+
+func corruptChunk(t *testing.T, root, chunkID string, data []byte) {
+	t.Helper()
+	path := filepath.Join(root, blobRoot, chunkID[:2], chunkID[2:4], chunkID)
+	if err := os.WriteFile(path, data, 0o600); err != nil {
+		t.Fatalf("corrupt chunk: %v", err)
+	}
+}

utils/config.go

@@ -15,6 +15,7 @@ type Config struct {
 	Address                   string
 	Port                      int
 	ChunkSize                 int
+	MaxObjectUploadBytes      int64
 	LogLevel                  string
 	LogFormat                 string
 	AuditLog                  bool
@@ -38,8 +39,9 @@ func NewConfig() *Config {
 	config := &Config{
 		DataPath:             sanitizeDataPath(os.Getenv("DATA_PATH")),
 		Address:              firstNonEmpty(strings.TrimSpace(os.Getenv("ADDRESS")), "0.0.0.0"),
-		Port:       envIntRange("PORT", 3000, 1, 65535),
+		Port:                 envIntRange("PORT", 2600, 1, 65535),
 		ChunkSize:            envIntRange("CHUNK_SIZE", 8192000, 1, 64*1024*1024),
+		MaxObjectUploadBytes: envInt64Range("FS_MAX_OBJECT_UPLOAD_BYTES", 5*1024*1024*1024, 1, 5*1024*1024*1024),
 		LogLevel:             strings.ToLower(firstNonEmpty(strings.TrimSpace(os.Getenv("LOG_LEVEL")), "info")),
 		LogFormat:            strings.ToLower(firstNonEmpty(strings.TrimSpace(os.Getenv("LOG_FORMAT")), strings.TrimSpace(os.Getenv("LOG_TYPE")), "text")),
 		AuditLog:             envBool("AUDIT_LOG", true),
@@ -82,6 +84,21 @@ func envIntRange(key string, defaultValue, minValue, maxValue int) int {
 	return value
 }
 
+func envInt64Range(key string, defaultValue, minValue, maxValue int64) int64 {
+	raw := strings.TrimSpace(os.Getenv(key))
+	if raw == "" {
+		return defaultValue
+	}
+	value, err := strconv.ParseInt(raw, 10, 64)
+	if err != nil {
+		return defaultValue
+	}
+	if value < minValue || value > maxValue {
+		return defaultValue
+	}
+	return value
+}
+
 func envBool(key string, defaultValue bool) bool {
 	raw := strings.TrimSpace(os.Getenv(key))
 	if raw == "" {

utils/config_test.go

@@ -0,0 +1,21 @@
+package utils
+
+import "testing"
+
+func TestEnvInt64Range(t *testing.T) {
+	t.Setenv("TEST_INT64_RANGE", "42")
+	if got := envInt64Range("TEST_INT64_RANGE", 10, 1, 100); got != 42 {
+		t.Fatalf("envInt64Range valid = %d, want 42", got)
+	}
+}
+
+func TestEnvInt64RangeFallsBackForInvalidValues(t *testing.T) {
+	t.Setenv("TEST_INT64_RANGE", "invalid")
+	if got := envInt64Range("TEST_INT64_RANGE", 10, 1, 100); got != 10 {
+		t.Fatalf("envInt64Range invalid = %d, want 10", got)
+	}
+	t.Setenv("TEST_INT64_RANGE", "101")
+	if got := envInt64Range("TEST_INT64_RANGE", 10, 1, 100); got != 10 {
+		t.Fatalf("envInt64Range too large = %d, want 10", got)
+	}
+}