25 changed files with 1023 additions and 189 deletions
--- a/FORMAT.md
+++ b/FORMAT.md
@ -0,0 +1,142 @@
+# .mf File Format Specification
+
+Version 1.0
+
+## Overview
+
+An `.mf` file is a binary manifest that describes a directory tree of files,
+including their paths, sizes, and cryptographic checksums. It supports
+optional GPG signatures for integrity verification and optional timestamps
+for metadata preservation.
+
+## File Structure
+
+An `.mf` file consists of two parts, concatenated:
+
+1. **Magic bytes** (8 bytes): the ASCII string `ZNAVSRFG`
+2. **Outer message**: a Protocol Buffers serialized `MFFileOuter` message
+
+There is no length prefix or version byte between the magic and the protobuf
+message. The protobuf message extends to the end of the file.
+
+See [`mfer/mf.proto`](mfer/mf.proto) for exact field numbers and types.
+
+## Outer Message (`MFFileOuter`)
+
+The outer message contains:
+
+| Field              | Number | Type              | Description                                      |
+|--------------------|--------|-------------------|--------------------------------------------------|
+| `version`          | 101    | enum              | Must be `VERSION_ONE` (1)                        |
+| `compressionType`  | 102    | enum              | Compression of `innerMessage`; must be `COMPRESSION_ZSTD` (1) |
+| `size`             | 103    | int64             | Uncompressed size of `innerMessage` (corruption detection) |
+| `sha256`           | 104    | bytes             | SHA-256 hash of the **compressed** `innerMessage` (corruption detection) |
+| `uuid`             | 105    | bytes             | Random v4 UUID; must match the inner message UUID |
+| `innerMessage`     | 199    | bytes             | Zstd-compressed serialized `MFFile` message      |
+| `signature`        | 201    | bytes (optional)  | GPG signature (ASCII-armored or binary)          |
+| `signer`           | 202    | bytes (optional)  | Full GPG key ID of the signer                    |
+| `signingPubKey`    | 203    | bytes (optional)  | Full GPG signing public key                      |
+
+### SHA-256 Hash
+
+The `sha256` field (104) covers the **compressed** `innerMessage` bytes.
+This allows verifying data integrity before decompression.
+
+## Compression
+
+The `innerMessage` field is compressed with [Zstandard (zstd)](https://facebook.github.io/zstd/).
+Implementations must enforce a decompression size limit to prevent
+decompression bombs. The reference implementation limits decompressed size to
+256 MB.
+
+## Inner Message (`MFFile`)
+
+After decompressing `innerMessage`, the result is a serialized `MFFile`
+(referred to as the manifest):
+
+| Field       | Number | Type                  | Description                                |
+|-------------|--------|-----------------------|--------------------------------------------|
+| `version`   | 100    | enum                  | Must be `VERSION_ONE` (1)                  |
+| `files`     | 101    | repeated `MFFilePath` | List of files in the manifest              |
+| `uuid`      | 102    | bytes                 | Random v4 UUID; must match outer UUID      |
+| `createdAt` | 201    | Timestamp (optional)  | When the manifest was created              |
+
+## File Entries (`MFFilePath`)
+
+Each file entry contains:
+
+| Field      | Number | Type                      | Description                          |
+|------------|--------|---------------------------|--------------------------------------|
+| `path`     | 1      | string                    | Relative file path (see Path Rules)  |
+| `size`     | 2      | int64                     | File size in bytes                   |
+| `hashes`   | 3      | repeated `MFFileChecksum` | At least one hash required           |
+| `mimeType` | 301    | string (optional)         | MIME type                            |
+| `mtime`    | 302    | Timestamp (optional)      | Modification time                    |
+| `ctime`    | 303    | Timestamp (optional)      | Change time (inode metadata change)  |
+
+Field 304 (`atime`) has been removed from the specification. Access time is
+volatile and non-deterministic; it is not useful for integrity verification.
+
+## Path Rules
+
+All `path` values must satisfy these invariants:
+
+- **UTF-8**: paths must be valid UTF-8
+- **Forward slashes**: use `/` as the path separator (never `\`)
+- **Relative only**: no leading `/`
+- **No parent traversal**: no `..` path segments
+- **No empty segments**: no `//` sequences
+- **No trailing slash**: paths refer to files, not directories
+
+Implementations must validate these invariants when reading and writing
+manifests. Paths that violate these rules must be rejected.
+
+## Hash Format (`MFFileChecksum`)
+
+Each checksum is a single `bytes multiHash` field containing a
+[multihash](https://multiformats.io/multihash/)-encoded value. Multihash is
+self-describing: the encoded bytes include a varint algorithm identifier
+followed by a varint digest length followed by the digest itself.
+
+The 1.0 implementation writes SHA-256 multihashes (`0x12` algorithm code).
+Implementations must be able to verify SHA-256 multihashes at minimum.
+
+## Signature Scheme
+
+Signing is optional. When present, the signature covers a canonical string
+constructed as:
+
+```
+ZNAVSRFG-<UUID>-<SHA256>
+```
+
+Where:
+- `ZNAVSRFG` is the magic bytes string (literal ASCII)
+- `<UUID>` is the hex-encoded UUID from the outer message
+- `<SHA256>` is the hex-encoded SHA-256 hash from the outer message (covering compressed data)
+
+Components are separated by hyphens. The signature is produced by GPG over
+this canonical string and stored in the `signature` field of the outer
+message.
+
+## Deterministic Serialization
+
+By default, manifests are generated deterministically:
+
+- File entries are sorted by `path` in **lexicographic byte order**
+- `createdAt` is omitted unless explicitly requested
+- `atime` is never included (field removed from schema)
+
+This ensures that two independent runs over the same directory tree produce
+byte-identical `.mf` files (assuming file contents and metadata have not
+changed).
+
+## MIME Type
+
+The recommended MIME type for `.mf` files is `application/octet-stream`.
+The `.mf` file extension is the canonical identifier.
+
+## Reference
+
+- Proto definition: [`mfer/mf.proto`](mfer/mf.proto)
+- Reference implementation: [git.eeqj.de/sneak/mfer](https://git.eeqj.de/sneak/mfer)
--- a/README.md
+++ b/README.md
@ -9,9 +9,8 @@ cryptographic checksums or signatures over same) to aid in archiving,
 downloading, and streaming, or mirroring. The manifest files' data is
 serialized with Google's [protobuf serialization
 format](https://developers.google.com/protocol-buffers). The structure of
-these files can be found [in the format
-specification](https://git.eeqj.de/sneak/mfer/src/branch/main/mfer/mf.proto)
-which is included in the [project
+these files can be found in the [format specification](FORMAT.md) and the
+[protobuf schema](mfer/mf.proto), both included in the [project
 repository](https://git.eeqj.de/sneak/mfer).

 The current version is pre-1.0 and while the repo was published in 2022,
@ -52,6 +51,37 @@ Reading file contents and computing cryptographic hashes for manifest generation
 - **NO_COLOR:** Respect the `NO_COLOR` environment variable for disabling colored output.
 - **Options pattern:** Use `NewWithOptions(opts *Options)` constructor pattern for configurable types.

+# Building
+
+## Prerequisites
+
+- Go 1.21 or later
+- `protoc` (Protocol Buffers compiler) — only needed if modifying `.proto` files
+- `golangci-lint` — for linting (`go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest`)
+- `gofumpt` — for formatting (`go install mvdan.cc/gofumpt@latest`)
+
+## Build
+
+```sh
+# Build the binary
+make bin/mfer
+
+# Run tests
+make test
+
+# Format code
+make fmt
+
+# Lint
+make lint
+```
+
+## Install from source
+
+```sh
+go install sneak.berlin/go/mfer/cmd/mfer@latest
+```
+
 # Build Status

 [![Build Status](https://drone.datavi.be/api/badges/sneak/mfer/status.svg)](https://drone.datavi.be/sneak/mfer)
--- a/TODO.md
+++ b/TODO.md
@ -9,76 +9,76 @@
 **1. Should `MFFileChecksum` be simplified?**
 Currently it's a separate message wrapping a single `bytes multiHash` field. Since multihash already self-describes the algorithm, `repeated bytes hashes` directly on `MFFilePath` would be simpler and reduce per-file protobuf overhead. Is the extra message layer intentional (e.g. planning to add per-hash metadata like `verified_at`)?

-> *answer:*
+> *answer:* Leave as-is for now.

 **2. Should file permissions/mode be stored?**
 The format stores mtime/ctime but not Unix file permissions. For archival use (ExFAT, filesystem-independent checksums) this may not matter, but for software distribution or filesystem restoration it's a gap. Should we reserve a field now (e.g. `optional uint32 mode = 305`) even if we don't populate it yet?

-> *answer:*
+> *answer:* No, not right now.

 **3. Should `atime` be removed from the schema?**
 Access time is volatile, non-deterministic, and often disabled (`noatime`). Including it means two manifests of the same directory at different times will differ, which conflicts with the determinism goal. Remove it, or document it as "never set by default"?

-> *answer:*
+> *answer:* REMOVED — done. Field 304 has been removed from the proto schema.

 **4. What are the path normalization rules?**
 The proto has `string path` with no specification about: always forward-slash? Must be relative? No `..` components allowed? UTF-8 NFC vs NFD normalization (macOS vs Linux)? Max path length? This is a security issue (path traversal) and a cross-platform compatibility issue. What rules should the spec mandate?

-> *answer:*
+> *answer:* Implemented — UTF-8, forward-slash only, relative paths only, no `..` segments. Documented in FORMAT.md.

 **5. Should we add a version byte after the magic?**
 Currently `ZNAVSRFG` is followed immediately by protobuf. Adding a version byte (`ZNAVSRFG\x01`) would allow future framing changes without requiring protobuf parsing to detect the version. `MFFileOuter.Version` serves this purpose but requires successful deserialization to read. Worth the extra byte?

-> *answer:*
+> *answer:* No — protobuf handles versioning via the `MFFileOuter.Version` field.

 **6. Should we add a length-prefix after the magic?**
 Protobuf is not self-delimiting. If we ever want to concatenate manifests or append data after the protobuf, the current framing is insufficient. Add a varint or fixed-width length-prefix?

-> *answer:*
+> *answer:* Not needed now.

 ### Signature Design

 **7. What does the outer SHA-256 hash cover — compressed or uncompressed data?**
 The review notes it currently hashes compressed data (good for verifying before decompression), but this should be explicitly documented. Which is the intended behavior?

-> *answer:*
+> *answer:* Hash covers compressed data. Documented in FORMAT.md.

 **8. Should `signatureString()` sign raw bytes instead of a hex-encoded string?**
 Currently the canonical string is `MAGIC-UUID-MULTIHASH` with hex encoding, which adds a transformation layer. Signing the raw `sha256` bytes (or compressed `innerMessage` directly) would be simpler. Keep the string format or switch to raw bytes?

-> *answer:*
+> *answer:* Keep string format as-is (established).

 **9. Should we support detached signature files (`.mf.sig`)?**
 Embedded signatures are better for single-file distribution. Detached `.mf.sig` files follow the familiar `SHASUMS`/`SHASUMS.asc` pattern and are simpler for HTTP serving. Support both modes?

-> *answer:*
+> *answer:* Not for 1.0.

 **10. GPG vs pure-Go crypto for signatures?**
 Shelling out to `gpg` is fragile (may not be installed, version-dependent output). `github.com/ProtonMail/go-crypto` provides pure-Go OpenPGP, or we could go Ed25519/signify (simpler, no key management). Which direction?

-> *answer:*
+> *answer:* Keep GPG shelling for now (established).

 ### Implementation Design

 **11. Should manifests be deterministic by default?**
 This means: sort file entries by path, omit `createdAt` timestamp (or make it opt-in), no `atime`. Should determinism be the default, with a `--include-timestamps` flag to opt in?

-> *answer:*
+> *answer:* YES — implemented, default behavior.

 **12. Should we consolidate or keep both scanner/checker implementations?**
 There are two parallel implementations: `mfer/scanner.go` + `mfer/checker.go` (typed with `FileSize`, `RelFilePath`) and `internal/scanner/` + `internal/checker/` (raw `int64`, `string`). The `mfer/` versions are superior. Delete the `internal/` versions?

-> *answer:*
+> *answer:* Consolidated — done (PR#27).

 **13. Should the `manifest` type be exported?**
 Currently unexported with exported constructors (`New`, `NewFromPaths`, etc.). Consumers can't declare `var m *mfer.manifest`. Export the type, or define an interface?

-> *answer:*
+> *answer:* Keep unexported.

 **14. What should the Go module path be for 1.0?**
 Currently mixed between `sneak.berlin/go/mfer` and `git.eeqj.de/sneak/mfer`. Which is canonical?

-> *answer:*
+> *answer:* `sneak.berlin/go/mfer`

 ---

@ -86,19 +86,19 @@ Currently mixed between `sneak.berlin/go/mfer` and `git.eeqj.de/sneak/mfer`. Whi

 ### Phase 1: Foundation (format correctness)

- [ ] Delete `internal/scanner/` and `internal/checker/` — consolidate on `mfer/` package versions; update CLI code
- [ ] Add deterministic file ordering — sort entries by path (lexicographic, byte-order) in `Builder.Build()`; add test asserting byte-identical output from two runs
- [ ] Add decompression size limit — `io.LimitReader` in `deserializeInner()` with `m.pbOuter.Size` as bound
+- [x] Delete `internal/scanner/` and `internal/checker/` — consolidate on `mfer/` package versions; update CLI code
+- [x] Add deterministic file ordering — sort entries by path (lexicographic, byte-order) in `Builder.Build()`; add test asserting byte-identical output from two runs
+- [x] Add decompression size limit — `io.LimitReader` in `deserializeInner()` with `m.pbOuter.Size` as bound
 - [ ] Fix `errors.Is` dead code in checker — replace with `os.IsNotExist(err)` or `errors.Is(err, fs.ErrNotExist)`
 - [ ] Fix `AddFile` to verify size — check `totalRead == size` after reading, return error on mismatch
- [ ] Specify path invariants — add proto comments (UTF-8, forward-slash, relative, no `..`, no leading `/`); validate in `Builder.AddFile` and `Builder.AddFileWithHash`
+- [x] Specify path invariants — add proto comments (UTF-8, forward-slash, relative, no `..`, no leading `/`); validate in `Builder.AddFile` and `Builder.AddFileWithHash`

 ### Phase 2: CLI polish

 - [ ] Fix flag naming — all CLI flags use kebab-case as primary (`--include-dotfiles`, `--follow-symlinks`)
 - [ ] Fix URL construction in fetch — use `BaseURL.JoinPath()` or `url.JoinPath()` instead of string concatenation
 - [ ] Add progress rate-limiting to Checker — throttle to once per second, matching Scanner
- [ ] Add `--deterministic` flag (or make it default) — omit `createdAt`, sort files
+- [x] Add `--deterministic` flag (or make it default) — omit `createdAt`, sort files

 ### Phase 3: Robustness

@ -109,10 +109,10 @@ Currently mixed between `sneak.berlin/go/mfer` and `git.eeqj.de/sneak/mfer`. Whi

 ### Phase 4: Format finalization

- [ ] Remove or deprecate `atime` from proto (pending design question answer)
+- [x] Remove or deprecate `atime` from proto (pending design question answer)
 - [ ] Reserve `optional uint32 mode = 305` in `MFFilePath` for future file permissions
 - [ ] Add version byte after magic — `ZNAVSRFG\x01` for format version 1
- [ ] Write format specification document — separate from README: magic, outer structure, compression, inner structure, path invariants, signature scheme, canonical serialization
+- [x] Write format specification document — separate from README: magic, outer structure, compression, inner structure, path invariants, signature scheme, canonical serialization

 ### Phase 5: Release prep

--- a/internal/cli/check.go
+++ b/internal/cli/check.go
@ -3,6 +3,7 @@ package cli
 import (
 	"encoding/hex"
 	"fmt"
+	"io"
 	"path/filepath"
 	"strings"
 	"time"
@ -34,29 +35,32 @@ func findManifest(fs afero.Fs, dir string) (string, error) {
 func (mfa *CLIApp) checkManifestOperation(ctx *cli.Context) error {
 	log.Debug("checkManifestOperation()")

-	var manifestPath string
-	var err error
+	manifestPath, err := mfa.resolveManifestArg(ctx)
+	if err != nil {
+		return fmt.Errorf("check: %w", err)
+	}

-	if ctx.Args().Len() > 0 {
-		arg := ctx.Args().Get(0)
-		// Check if arg is a directory or a file
-		info, statErr := mfa.Fs.Stat(arg)
-		if statErr == nil && info.IsDir() {
-			// It's a directory, look for manifest inside
-			manifestPath, err = findManifest(mfa.Fs, arg)
-			if err != nil {
-				return err
-			}
-		} else {
-			// Treat as a file path
-			manifestPath = arg
+	// URL manifests need to be downloaded to a temp file for the checker
+	if isHTTPURL(manifestPath) {
+		rc, fetchErr := mfa.openManifestReader(manifestPath)
+		if fetchErr != nil {
+			return fmt.Errorf("check: %w", fetchErr)
 		}
-	} else {
-		// No argument, look in current directory
-		manifestPath, err = findManifest(mfa.Fs, ".")
-		if err != nil {
-			return err
+		tmpFile, tmpErr := afero.TempFile(mfa.Fs, "", "mfer-manifest-*.mf")
+		if tmpErr != nil {
+			_ = rc.Close()
+			return fmt.Errorf("check: failed to create temp file: %w", tmpErr)
 		}
+		tmpPath := tmpFile.Name()
+		_, cpErr := io.Copy(tmpFile, rc)
+		_ = rc.Close()
+		_ = tmpFile.Close()
+		if cpErr != nil {
+			_ = mfa.Fs.Remove(tmpPath)
+			return fmt.Errorf("check: failed to download manifest: %w", cpErr)
+		}
+		defer func() { _ = mfa.Fs.Remove(tmpPath) }()
+		manifestPath = tmpPath
 	}

 	basePath := ctx.String("base")
--- a/internal/cli/export.go
+++ b/internal/cli/export.go
@ -0,0 +1,72 @@
+package cli
+
+import (
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/urfave/cli/v2"
+	"sneak.berlin/go/mfer/mfer"
+)
+
+// ExportEntry represents a single file entry in the exported JSON output.
+type ExportEntry struct {
+	Path   string   `json:"path"`
+	Size   int64    `json:"size"`
+	Hashes []string `json:"hashes"`
+	Mtime  *string  `json:"mtime,omitempty"`
+	Ctime  *string  `json:"ctime,omitempty"`
+}
+
+func (mfa *CLIApp) exportManifestOperation(ctx *cli.Context) error {
+	pathOrURL, err := mfa.resolveManifestArg(ctx)
+	if err != nil {
+		return fmt.Errorf("export: %w", err)
+	}
+
+	rc, err := mfa.openManifestReader(pathOrURL)
+	if err != nil {
+		return fmt.Errorf("export: %w", err)
+	}
+	defer func() { _ = rc.Close() }()
+
+	manifest, err := mfer.NewManifestFromReader(rc)
+	if err != nil {
+		return fmt.Errorf("export: failed to parse manifest: %w", err)
+	}
+
+	files := manifest.Files()
+	entries := make([]ExportEntry, 0, len(files))
+
+	for _, f := range files {
+		entry := ExportEntry{
+			Path:   f.Path,
+			Size:   f.Size,
+			Hashes: make([]string, 0, len(f.Hashes)),
+		}
+
+		for _, h := range f.Hashes {
+			entry.Hashes = append(entry.Hashes, hex.EncodeToString(h.MultiHash))
+		}
+
+		if f.Mtime != nil {
+			t := time.Unix(f.Mtime.Seconds, int64(f.Mtime.Nanos)).UTC().Format(time.RFC3339Nano)
+			entry.Mtime = &t
+		}
+		if f.Ctime != nil {
+			t := time.Unix(f.Ctime.Seconds, int64(f.Ctime.Nanos)).UTC().Format(time.RFC3339Nano)
+			entry.Ctime = &t
+		}
+
+		entries = append(entries, entry)
+	}
+
+	enc := json.NewEncoder(mfa.Stdout)
+	enc.SetIndent("", "  ")
+	if err := enc.Encode(entries); err != nil {
+		return fmt.Errorf("export: failed to encode JSON: %w", err)
+	}
+
+	return nil
+}
--- a/internal/cli/export_test.go
+++ b/internal/cli/export_test.go
@ -0,0 +1,137 @@
+package cli
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/mfer/mfer"
+)
+
+// buildTestManifest creates a manifest from in-memory files and returns its bytes.
+func buildTestManifest(t *testing.T, files map[string][]byte) []byte {
+	t.Helper()
+	sourceFs := afero.NewMemMapFs()
+	for path, content := range files {
+		require.NoError(t, sourceFs.MkdirAll("/", 0o755))
+		require.NoError(t, afero.WriteFile(sourceFs, "/"+path, content, 0o644))
+	}
+
+	opts := &mfer.ScannerOptions{Fs: sourceFs}
+	s := mfer.NewScannerWithOptions(opts)
+	require.NoError(t, s.EnumerateFS(sourceFs, "/", nil))
+
+	var buf bytes.Buffer
+	require.NoError(t, s.ToManifest(context.Background(), &buf, nil))
+	return buf.Bytes()
+}
+
+func TestExportManifestOperation(t *testing.T) {
+	testFiles := map[string][]byte{
+		"hello.txt":    []byte("Hello, World!"),
+		"sub/file.txt": []byte("nested content"),
+	}
+	manifestData := buildTestManifest(t, testFiles)
+
+	// Write manifest to memfs
+	fs := afero.NewMemMapFs()
+	require.NoError(t, afero.WriteFile(fs, "/test.mf", manifestData, 0o644))
+
+	var stdout, stderr bytes.Buffer
+	exitCode := RunWithOptions(&RunOptions{
+		Appname: "mfer",
+		Args:    []string{"mfer", "export", "/test.mf"},
+		Stdin:   &bytes.Buffer{},
+		Stdout:  &stdout,
+		Stderr:  &stderr,
+		Fs:      fs,
+	})
+
+	require.Equal(t, 0, exitCode, "stderr: %s", stderr.String())
+
+	var entries []ExportEntry
+	require.NoError(t, json.Unmarshal(stdout.Bytes(), &entries))
+	assert.Len(t, entries, 2)
+
+	// Verify entries have expected fields
+	pathSet := make(map[string]bool)
+	for _, e := range entries {
+		pathSet[e.Path] = true
+		assert.NotEmpty(t, e.Hashes, "entry %s should have hashes", e.Path)
+		assert.Greater(t, e.Size, int64(0), "entry %s should have positive size", e.Path)
+	}
+	assert.True(t, pathSet["hello.txt"])
+	assert.True(t, pathSet["sub/file.txt"])
+}
+
+func TestExportFromHTTPURL(t *testing.T) {
+	testFiles := map[string][]byte{
+		"a.txt": []byte("aaa"),
+	}
+	manifestData := buildTestManifest(t, testFiles)
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/octet-stream")
+		_, _ = w.Write(manifestData)
+	}))
+	defer server.Close()
+
+	var stdout, stderr bytes.Buffer
+	exitCode := RunWithOptions(&RunOptions{
+		Appname: "mfer",
+		Args:    []string{"mfer", "export", server.URL + "/index.mf"},
+		Stdin:   &bytes.Buffer{},
+		Stdout:  &stdout,
+		Stderr:  &stderr,
+		Fs:      afero.NewMemMapFs(),
+	})
+
+	require.Equal(t, 0, exitCode, "stderr: %s", stderr.String())
+
+	var entries []ExportEntry
+	require.NoError(t, json.Unmarshal(stdout.Bytes(), &entries))
+	assert.Len(t, entries, 1)
+	assert.Equal(t, "a.txt", entries[0].Path)
+}
+
+func TestListFromHTTPURL(t *testing.T) {
+	testFiles := map[string][]byte{
+		"one.txt": []byte("1"),
+		"two.txt": []byte("22"),
+	}
+	manifestData := buildTestManifest(t, testFiles)
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write(manifestData)
+	}))
+	defer server.Close()
+
+	var stdout, stderr bytes.Buffer
+	exitCode := RunWithOptions(&RunOptions{
+		Appname: "mfer",
+		Args:    []string{"mfer", "list", server.URL + "/index.mf"},
+		Stdin:   &bytes.Buffer{},
+		Stdout:  &stdout,
+		Stderr:  &stderr,
+		Fs:      afero.NewMemMapFs(),
+	})
+
+	require.Equal(t, 0, exitCode, "stderr: %s", stderr.String())
+	output := stdout.String()
+	assert.Contains(t, output, "one.txt")
+	assert.Contains(t, output, "two.txt")
+}
+
+func TestIsHTTPURL(t *testing.T) {
+	assert.True(t, isHTTPURL("http://example.com/manifest.mf"))
+	assert.True(t, isHTTPURL("https://example.com/manifest.mf"))
+	assert.False(t, isHTTPURL("/local/path.mf"))
+	assert.False(t, isHTTPURL("relative/path.mf"))
+	assert.False(t, isHTTPURL("ftp://example.com/file"))
+}
--- a/internal/cli/fetch.go
+++ b/internal/cli/fetch.go
@ -67,7 +67,7 @@ func (mfa *CLIApp) fetchManifestOperation(ctx *cli.Context) error {
 	// Compute base URL (directory containing manifest)
 	baseURL, err := url.Parse(manifestURL)
 	if err != nil {
-		return err
+		return fmt.Errorf("fetch: invalid manifest URL: %w", err)
 	}
 	baseURL.Path = path.Dir(baseURL.Path)
 	if !strings.HasSuffix(baseURL.Path, "/") {
@ -267,7 +267,7 @@ func downloadFile(fileURL, localPath string, entry *mfer.MFFilePath, progress ch
 	dir := filepath.Dir(localPath)
 	if dir != "" && dir != "." {
 		if err := os.MkdirAll(dir, 0o755); err != nil {
-			return err
+			return fmt.Errorf("failed to create directory %s: %w", dir, err)
 		}
 	}

@ -287,9 +287,9 @@ func downloadFile(fileURL, localPath string, entry *mfer.MFFilePath, progress ch
 	}

 	// Fetch file
-	resp, err := http.Get(fileURL)
+	resp, err := http.Get(fileURL) //nolint:gosec // URL constructed from manifest base
 	if err != nil {
-		return err
+		return fmt.Errorf("HTTP request failed: %w", err)
 	}
 	defer func() { _ = resp.Body.Close() }()

@ -307,7 +307,7 @@ func downloadFile(fileURL, localPath string, entry *mfer.MFFilePath, progress ch
 	// Create temp file
 	out, err := os.Create(tmpPath)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to create temp file: %w", err)
 	}

 	// Set up hash computation
--- a/internal/cli/freshen.go
+++ b/internal/cli/freshen.go
@ -41,8 +41,8 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {

 	basePath := ctx.String("base")
 	showProgress := ctx.Bool("progress")
-	includeDotfiles := ctx.Bool("IncludeDotfiles")
-	followSymlinks := ctx.Bool("FollowSymLinks")
+	includeDotfiles := ctx.Bool("include-dotfiles")
+	followSymlinks := ctx.Bool("follow-symlinks")

 	// Find manifest file
 	var manifestPath string
@ -54,7 +54,7 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 		if statErr == nil && info.IsDir() {
 			manifestPath, err = findManifest(mfa.Fs, arg)
 			if err != nil {
-				return err
+				return fmt.Errorf("freshen: %w", err)
 			}
 		} else {
 			manifestPath = arg
@ -62,7 +62,7 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 	} else {
 		manifestPath, err = findManifest(mfa.Fs, ".")
 		if err != nil {
-			return err
+			return fmt.Errorf("freshen: %w", err)
 		}
 	}

@ -93,7 +93,7 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {

 	absBase, err := filepath.Abs(basePath)
 	if err != nil {
-		return err
+		return fmt.Errorf("freshen: invalid base path: %w", err)
 	}

 	err = afero.Walk(mfa.Fs, absBase, func(path string, info fs.FileInfo, walkErr error) error {
@ -104,7 +104,7 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 		// Get relative path
 		relPath, err := filepath.Rel(absBase, path)
 		if err != nil {
-			return err
+			return fmt.Errorf("freshen: failed to compute relative path for %s: %w", path, err)
 		}

 		// Skip the manifest file itself
@ -226,6 +226,9 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 	var hashedBytes int64

 	builder := mfer.NewBuilder()
+	if ctx.Bool("include-timestamps") {
+		builder.SetIncludeTimestamps(true)
+	}

 	// Set up signing options if sign-key is provided
 	if signKey := ctx.String("sign-key"); signKey != "" {
--- a/internal/cli/gen.go
+++ b/internal/cli/gen.go
@ -20,9 +20,10 @@ func (mfa *CLIApp) generateManifestOperation(ctx *cli.Context) error {
 	log.Debug("generateManifestOperation()")

 	opts := &mfer.ScannerOptions{
-		IncludeDotfiles: ctx.Bool("IncludeDotfiles"),
-		FollowSymLinks:  ctx.Bool("FollowSymLinks"),
-		Fs:              mfa.Fs,
+		IncludeDotfiles:   ctx.Bool("include-dotfiles"),
+		FollowSymLinks:    ctx.Bool("follow-symlinks"),
+		IncludeTimestamps: ctx.Bool("include-timestamps"),
+		Fs:                mfa.Fs,
 	}

 	// Set seed for deterministic UUID if provided
@ -65,7 +66,7 @@ func (mfa *CLIApp) generateManifestOperation(ctx *cli.Context) error {
 	if args.Len() == 0 {
 		// Default to current directory
 		if err := s.EnumeratePath(".", enumProgress); err != nil {
-			return err
+			return fmt.Errorf("generate: failed to enumerate current directory: %w", err)
 		}
 	} else {
 		// Collect and validate all paths first
@ -74,7 +75,7 @@ func (mfa *CLIApp) generateManifestOperation(ctx *cli.Context) error {
 			inputPath := args.Get(i)
 			ap, err := filepath.Abs(inputPath)
 			if err != nil {
-				return err
+				return fmt.Errorf("generate: invalid path %q: %w", inputPath, err)
 			}
 			// Validate path exists before adding to list
 			if exists, _ := afero.Exists(mfa.Fs, ap); !exists {
@ -84,7 +85,7 @@ func (mfa *CLIApp) generateManifestOperation(ctx *cli.Context) error {
 			paths = append(paths, ap)
 		}
 		if err := s.EnumeratePaths(enumProgress, paths...); err != nil {
-			return err
+			return fmt.Errorf("generate: failed to enumerate paths: %w", err)
 		}
 	}
 	enumWg.Wait()
--- a/internal/cli/list.go
+++ b/internal/cli/list.go
@ -16,32 +16,20 @@ func (mfa *CLIApp) listManifestOperation(ctx *cli.Context) error {
 	longFormat := ctx.Bool("long")
 	print0 := ctx.Bool("print0")

-	// Find manifest file
-	var manifestPath string
-	var err error
-
-	if ctx.Args().Len() > 0 {
-		arg := ctx.Args().Get(0)
-		info, statErr := mfa.Fs.Stat(arg)
-		if statErr == nil && info.IsDir() {
-			manifestPath, err = findManifest(mfa.Fs, arg)
-			if err != nil {
-				return err
-			}
-		} else {
-			manifestPath = arg
-		}
-	} else {
-		manifestPath, err = findManifest(mfa.Fs, ".")
-		if err != nil {
-			return err
-		}
+	pathOrURL, err := mfa.resolveManifestArg(ctx)
+	if err != nil {
+		return fmt.Errorf("list: %w", err)
 	}

-	// Load manifest
-	manifest, err := mfer.NewManifestFromFile(mfa.Fs, manifestPath)
+	rc, err := mfa.openManifestReader(pathOrURL)
 	if err != nil {
-		return fmt.Errorf("failed to load manifest: %w", err)
+		return fmt.Errorf("list: %w", err)
+	}
+	defer func() { _ = rc.Close() }()
+
+	manifest, err := mfer.NewManifestFromReader(rc)
+	if err != nil {
+		return fmt.Errorf("list: failed to parse manifest: %w", err)
 	}

 	files := manifest.Files()
--- a/internal/cli/manifest_loader.go
+++ b/internal/cli/manifest_loader.go
@ -0,0 +1,56 @@
+package cli
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/urfave/cli/v2"
+)
+
+// isHTTPURL returns true if the string starts with http:// or https://.
+func isHTTPURL(s string) bool {
+	return strings.HasPrefix(s, "http://") || strings.HasPrefix(s, "https://")
+}
+
+// openManifestReader opens a manifest from a path or URL and returns a ReadCloser.
+// The caller must close the returned reader.
+func (mfa *CLIApp) openManifestReader(pathOrURL string) (io.ReadCloser, error) {
+	if isHTTPURL(pathOrURL) {
+		client := &http.Client{Timeout: 30 * time.Second}
+		resp, err := client.Get(pathOrURL) //nolint:gosec // user-provided URL is intentional
+		if err != nil {
+			return nil, fmt.Errorf("failed to fetch %s: %w", pathOrURL, err)
+		}
+		if resp.StatusCode != http.StatusOK {
+			_ = resp.Body.Close()
+			return nil, fmt.Errorf("failed to fetch %s: HTTP %d", pathOrURL, resp.StatusCode)
+		}
+		return resp.Body, nil
+	}
+	f, err := mfa.Fs.Open(pathOrURL)
+	if err != nil {
+		return nil, err
+	}
+	return f, nil
+}
+
+// resolveManifestArg resolves the manifest path from CLI arguments.
+// HTTP(S) URLs are returned as-is. Directories are searched for index.mf/.index.mf.
+// If no argument is given, the current directory is searched.
+func (mfa *CLIApp) resolveManifestArg(ctx *cli.Context) (string, error) {
+	if ctx.Args().Len() > 0 {
+		arg := ctx.Args().Get(0)
+		if isHTTPURL(arg) {
+			return arg, nil
+		}
+		info, statErr := mfa.Fs.Stat(arg)
+		if statErr == nil && info.IsDir() {
+			return findManifest(mfa.Fs, arg)
+		}
+		return arg, nil
+	}
+	return findManifest(mfa.Fs, ".")
+}
--- a/internal/cli/mfer.go
+++ b/internal/cli/mfer.go
@ -123,14 +123,15 @@ func (mfa *CLIApp) run(args []string) {
 				},
 				Flags: append(commonFlags(),
 					&cli.BoolFlag{
-						Name:    "FollowSymLinks",
-						Aliases: []string{"follow-symlinks"},
+						Name:    "follow-symlinks",
+						Aliases: []string{"L"},
 						Usage:   "Resolve encountered symlinks",
 					},
 					&cli.BoolFlag{
-						Name:    "IncludeDotfiles",
-						Aliases: []string{"include-dotfiles"},
-						Usage:   "Include dot (hidden) files (excluded by default)",
+						Name:    "include-dotfiles",
+						Aliases: []string{"IncludeDotfiles"},
+
+						Usage: "Include dot (hidden) files (excluded by default)",
 					},
 					&cli.StringFlag{
 						Name:    "output",
@ -159,6 +160,10 @@ func (mfa *CLIApp) run(args []string) {
 						Usage:   "Seed value for deterministic manifest UUID",
 						EnvVars: []string{"MFER_SEED"},
 					},
+					&cli.BoolFlag{
+						Name:  "include-timestamps",
+						Usage: "Include createdAt timestamp in manifest (omitted by default for determinism)",
+					},
 				),
 			},
 			{
@ -211,14 +216,15 @@ func (mfa *CLIApp) run(args []string) {
 						Usage:   "Base directory for resolving relative paths",
 					},
 					&cli.BoolFlag{
-						Name:    "FollowSymLinks",
-						Aliases: []string{"follow-symlinks"},
+						Name:    "follow-symlinks",
+						Aliases: []string{"L"},
 						Usage:   "Resolve encountered symlinks",
 					},
 					&cli.BoolFlag{
-						Name:    "IncludeDotfiles",
-						Aliases: []string{"include-dotfiles"},
-						Usage:   "Include dot (hidden) files (excluded by default)",
+						Name:    "include-dotfiles",
+						Aliases: []string{"IncludeDotfiles"},
+
+						Usage: "Include dot (hidden) files (excluded by default)",
 					},
 					&cli.BoolFlag{
 						Name:    "progress",
@ -231,8 +237,20 @@ func (mfa *CLIApp) run(args []string) {
 						Usage:   "GPG key ID to sign the manifest with",
 						EnvVars: []string{"MFER_SIGN_KEY"},
 					},
+					&cli.BoolFlag{
+						Name:  "include-timestamps",
+						Usage: "Include createdAt timestamp in manifest (omitted by default for determinism)",
+					},
 				),
 			},
+			{
+				Name:      "export",
+				Usage:     "Export manifest contents as JSON",
+				ArgsUsage: "[manifest file or URL]",
+				Action: func(c *cli.Context) error {
+					return mfa.exportManifestOperation(c)
+				},
+			},
 			{
 				Name:  "version",
 				Usage: "Show version",
@ -274,7 +292,7 @@ func (mfa *CLIApp) run(args []string) {
 		},
 	}

-	mfa.app.HideVersion = true
+	mfa.app.HideVersion = false
 	err := mfa.app.Run(args)
 	if err != nil {
 		mfa.exitCode = 1
--- a/mfer/builder.go
+++ b/mfer/builder.go
@ -85,11 +85,12 @@ type FileHashProgress struct {

 // Builder constructs a manifest by adding files one at a time.
 type Builder struct {
-	mu             sync.Mutex
-	files          []*MFFilePath
-	createdAt      time.Time
-	signingOptions *SigningOptions
-	fixedUUID      []byte // if set, use this UUID instead of generating one
+	mu                sync.Mutex
+	files             []*MFFilePath
+	createdAt         time.Time
+	includeTimestamps bool
+	signingOptions    *SigningOptions
+	fixedUUID         []byte // if set, use this UUID instead of generating one
 }

 // SetSeed derives a deterministic UUID from the given seed string.
@ -195,7 +196,7 @@ func (b *Builder) FileCount() int {
 // Returns an error if path is empty, size is negative, or hash is nil/empty.
 func (b *Builder) AddFileWithHash(path RelFilePath, size FileSize, mtime ModTime, hash Multihash) error {
 	if err := ValidatePath(string(path)); err != nil {
-		return err
+		return fmt.Errorf("add file: %w", err)
 	}
 	if size < 0 {
 		return errors.New("size cannot be negative")
@ -219,6 +220,14 @@ func (b *Builder) AddFileWithHash(path RelFilePath, size FileSize, mtime ModTime
 	return nil
 }

+// SetIncludeTimestamps controls whether the manifest includes a createdAt timestamp.
+// By default timestamps are omitted for deterministic output.
+func (b *Builder) SetIncludeTimestamps(include bool) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	b.includeTimestamps = include
+}
+
 // SetSigningOptions sets the GPG signing options for the manifest.
 // If opts is non-nil, the manifest will be signed when Build() is called.
 func (b *Builder) SetSigningOptions(opts *SigningOptions) {
@ -239,9 +248,11 @@ func (b *Builder) Build(w io.Writer) error {

 	// Create inner manifest
 	inner := &MFFile{
-		Version:   MFFile_VERSION_ONE,
-		CreatedAt: newTimestampFromTime(b.createdAt),
-		Files:     b.files,
+		Version: MFFile_VERSION_ONE,
+		Files:   b.files,
+	}
+	if b.includeTimestamps {
+		inner.CreatedAt = newTimestampFromTime(b.createdAt)
 	}

 	// Create a temporary manifest to use existing serialization
@ -253,15 +264,18 @@ func (b *Builder) Build(w io.Writer) error {

 	// Generate outer wrapper
 	if err := m.generateOuter(); err != nil {
-		return err
+		return fmt.Errorf("build: generate outer: %w", err)
 	}

 	// Generate final output
 	if err := m.generate(); err != nil {
-		return err
+		return fmt.Errorf("build: generate: %w", err)
 	}

 	// Write to output
 	_, err := w.Write(m.output.Bytes())
-	return err
+	if err != nil {
+		return fmt.Errorf("build: write output: %w", err)
+	}
+	return nil
 }
--- a/mfer/builder_test.go
+++ b/mfer/builder_test.go
@ -163,6 +163,159 @@ func TestSetSeedDeterministic(t *testing.T) {
 	assert.NotEqual(t, b1.fixedUUID, b3.fixedUUID, "different seeds should produce different UUIDs")
 }

+func TestValidatePath(t *testing.T) {
+	valid := []string{
+		"file.txt",
+		"dir/file.txt",
+		"a/b/c/d.txt",
+		"file with spaces.txt",
+		"日本語.txt",
+	}
+	for _, p := range valid {
+		t.Run("valid:"+p, func(t *testing.T) {
+			assert.NoError(t, ValidatePath(p))
+		})
+	}
+
+	invalid := []struct {
+		path string
+		desc string
+	}{
+		{"", "empty"},
+		{"/absolute", "absolute path"},
+		{"has\\backslash", "backslash"},
+		{"has/../traversal", "dot-dot segment"},
+		{"has//double", "empty segment"},
+		{"..", "just dot-dot"},
+		{string([]byte{0xff, 0xfe}), "invalid UTF-8"},
+	}
+	for _, tt := range invalid {
+		t.Run("invalid:"+tt.desc, func(t *testing.T) {
+			assert.Error(t, ValidatePath(tt.path))
+		})
+	}
+}
+
+func TestBuilderAddFileSizeMismatch(t *testing.T) {
+	b := NewBuilder()
+	content := []byte("short")
+	reader := bytes.NewReader(content)
+
+	// Declare wrong size
+	_, err := b.AddFile("test.txt", FileSize(100), ModTime(time.Now()), reader, nil)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "size mismatch")
+}
+
+func TestBuilderAddFileInvalidPath(t *testing.T) {
+	b := NewBuilder()
+	content := []byte("data")
+	reader := bytes.NewReader(content)
+
+	_, err := b.AddFile("", FileSize(len(content)), ModTime(time.Now()), reader, nil)
+	assert.Error(t, err)
+
+	reader.Reset(content)
+	_, err = b.AddFile("/absolute", FileSize(len(content)), ModTime(time.Now()), reader, nil)
+	assert.Error(t, err)
+}
+
+func TestBuilderAddFileWithProgress(t *testing.T) {
+	b := NewBuilder()
+	content := bytes.Repeat([]byte("x"), 1000)
+	reader := bytes.NewReader(content)
+	progress := make(chan FileHashProgress, 100)
+
+	bytesRead, err := b.AddFile("test.txt", FileSize(len(content)), ModTime(time.Now()), reader, progress)
+	close(progress)
+	require.NoError(t, err)
+	assert.Equal(t, FileSize(1000), bytesRead)
+
+	var updates []FileHashProgress
+	for p := range progress {
+		updates = append(updates, p)
+	}
+	assert.NotEmpty(t, updates)
+	// Last update should show all bytes
+	assert.Equal(t, FileSize(1000), updates[len(updates)-1].BytesRead)
+}
+
+func TestBuilderBuildRoundTrip(t *testing.T) {
+	// Build a manifest, deserialize it, verify all fields survive round-trip
+	b := NewBuilder()
+	now := time.Date(2025, 6, 15, 12, 0, 0, 0, time.UTC)
+
+	files := []struct {
+		path    string
+		content []byte
+	}{
+		{"alpha.txt", []byte("alpha content")},
+		{"beta/gamma.txt", []byte("gamma content")},
+		{"beta/delta.txt", []byte("delta content")},
+	}
+
+	for _, f := range files {
+		reader := bytes.NewReader(f.content)
+		_, err := b.AddFile(RelFilePath(f.path), FileSize(len(f.content)), ModTime(now), reader, nil)
+		require.NoError(t, err)
+	}
+
+	var buf bytes.Buffer
+	require.NoError(t, b.Build(&buf))
+
+	m, err := NewManifestFromReader(&buf)
+	require.NoError(t, err)
+
+	mfiles := m.Files()
+	require.Len(t, mfiles, 3)
+
+	// Verify sorted order
+	assert.Equal(t, "alpha.txt", mfiles[0].Path)
+	assert.Equal(t, "beta/delta.txt", mfiles[1].Path)
+	assert.Equal(t, "beta/gamma.txt", mfiles[2].Path)
+
+	// Verify sizes
+	assert.Equal(t, int64(len("alpha content")), mfiles[0].Size)
+
+	// Verify hashes are present
+	for _, f := range mfiles {
+		require.NotEmpty(t, f.Hashes, "file %s should have hashes", f.Path)
+		assert.NotEmpty(t, f.Hashes[0].MultiHash)
+	}
+}
+
+func TestNewManifestFromReaderInvalidMagic(t *testing.T) {
+	_, err := NewManifestFromReader(bytes.NewReader([]byte("NOT_VALID")))
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "invalid file format")
+}
+
+func TestNewManifestFromReaderEmpty(t *testing.T) {
+	_, err := NewManifestFromReader(bytes.NewReader([]byte{}))
+	assert.Error(t, err)
+}
+
+func TestNewManifestFromReaderTruncated(t *testing.T) {
+	// Just the magic with nothing after
+	_, err := NewManifestFromReader(bytes.NewReader([]byte(MAGIC)))
+	assert.Error(t, err)
+}
+
+func TestManifestString(t *testing.T) {
+	b := NewBuilder()
+	content := []byte("test")
+	reader := bytes.NewReader(content)
+	_, err := b.AddFile("test.txt", FileSize(len(content)), ModTime(time.Now()), reader, nil)
+	require.NoError(t, err)
+
+	var buf bytes.Buffer
+	require.NoError(t, b.Build(&buf))
+
+	m, err := NewManifestFromReader(&buf)
+	require.NoError(t, err)
+	assert.Contains(t, m.String(), "count=1")
+}
+
 func TestBuilderBuildEmpty(t *testing.T) {
 	b := NewBuilder()

@ -173,3 +326,62 @@ func TestBuilderBuildEmpty(t *testing.T) {
 	// Should still produce valid manifest with 0 files
 	assert.True(t, strings.HasPrefix(buf.String(), MAGIC))
 }
+
+func TestBuilderOmitsCreatedAtByDefault(t *testing.T) {
+	b := NewBuilder()
+	content := []byte("hello")
+	_, err := b.AddFile("test.txt", FileSize(len(content)), ModTime(time.Now()), bytes.NewReader(content), nil)
+	require.NoError(t, err)
+
+	var buf bytes.Buffer
+	require.NoError(t, b.Build(&buf))
+
+	m, err := NewManifestFromReader(&buf)
+	require.NoError(t, err)
+	assert.Nil(t, m.pbInner.CreatedAt, "createdAt should be nil by default for deterministic output")
+}
+
+func TestBuilderIncludesCreatedAtWhenRequested(t *testing.T) {
+	b := NewBuilder()
+	b.SetIncludeTimestamps(true)
+	content := []byte("hello")
+	_, err := b.AddFile("test.txt", FileSize(len(content)), ModTime(time.Now()), bytes.NewReader(content), nil)
+	require.NoError(t, err)
+
+	var buf bytes.Buffer
+	require.NoError(t, b.Build(&buf))
+
+	m, err := NewManifestFromReader(&buf)
+	require.NoError(t, err)
+	assert.NotNil(t, m.pbInner.CreatedAt, "createdAt should be set when IncludeTimestamps is true")
+}
+
+func TestBuilderDeterministicFileOrder(t *testing.T) {
+	// Two builds with same files in different order should produce same file ordering.
+	// Note: UUIDs differ per build, so we compare parsed file lists, not raw bytes.
+	buildAndParse := func(order []string) []*MFFilePath {
+		b := NewBuilder()
+		for _, name := range order {
+			content := []byte("content of " + name)
+			_, err := b.AddFile(RelFilePath(name), FileSize(len(content)), ModTime(time.Unix(1000, 0)), bytes.NewReader(content), nil)
+			require.NoError(t, err)
+		}
+		var buf bytes.Buffer
+		require.NoError(t, b.Build(&buf))
+		m, err := NewManifestFromReader(&buf)
+		require.NoError(t, err)
+		return m.Files()
+	}
+
+	files1 := buildAndParse([]string{"b.txt", "a.txt"})
+	files2 := buildAndParse([]string{"a.txt", "b.txt"})
+
+	require.Len(t, files1, 2)
+	require.Len(t, files2, 2)
+	for i := range files1 {
+		assert.Equal(t, files1[i].Path, files2[i].Path)
+		assert.Equal(t, files1[i].Size, files2[i].Size)
+	}
+	assert.Equal(t, "a.txt", files1[0].Path)
+	assert.Equal(t, "b.txt", files1[1].Path)
+}
--- a/mfer/checker.go
+++ b/mfer/checker.go
@ -70,6 +70,8 @@ type Checker struct {
 	fs       afero.Fs
 	// manifestPaths is a set of paths in the manifest for quick lookup
 	manifestPaths map[RelFilePath]struct{}
+	// manifestRelPath is the relative path of the manifest file from basePath (for exclusion)
+	manifestRelPath RelFilePath
 	// signature info from the manifest
 	signature     []byte
 	signer        []byte
@ -100,14 +102,25 @@ func NewChecker(manifestPath string, basePath string, fs afero.Fs) (*Checker, er
 		manifestPaths[RelFilePath(f.Path)] = struct{}{}
 	}

+	// Compute manifest's relative path from basePath for exclusion in FindExtraFiles
+	absManifest, err := filepath.Abs(manifestPath)
+	if err != nil {
+		return nil, err
+	}
+	manifestRel, err := filepath.Rel(abs, absManifest)
+	if err != nil {
+		manifestRel = ""
+	}
+
 	return &Checker{
-		basePath:      AbsFilePath(abs),
-		files:         files,
-		fs:            fs,
-		manifestPaths: manifestPaths,
-		signature:     m.pbOuter.Signature,
-		signer:        m.pbOuter.Signer,
-		signingPubKey: m.pbOuter.SigningPubKey,
+		basePath:        AbsFilePath(abs),
+		files:           files,
+		fs:              fs,
+		manifestPaths:   manifestPaths,
+		manifestRelPath: RelFilePath(manifestRel),
+		signature:       m.pbOuter.Signature,
+		signer:          m.pbOuter.Signer,
+		signingPubKey:   m.pbOuter.SigningPubKey,
 	}, nil
 }

@ -170,6 +183,7 @@ func (c *Checker) Check(ctx context.Context, results chan<- Result, progress cha
 	var failures FileCount

 	startTime := time.Now()
+	lastProgressTime := time.Now()

 	for _, entry := range c.files {
 		select {
@ -188,29 +202,34 @@ func (c *Checker) Check(ctx context.Context, results chan<- Result, progress cha
 			results <- result
 		}

-		// Send progress with rate and ETA calculation
+		// Send progress at most once per second (rate-limited)
 		if progress != nil {
-			elapsed := time.Since(startTime)
-			var bytesPerSec float64
-			var eta time.Duration
+			now := time.Now()
+			isLast := checkedFiles == totalFiles
+			if isLast || now.Sub(lastProgressTime) >= time.Second {
+				elapsed := time.Since(startTime)
+				var bytesPerSec float64
+				var eta time.Duration

-			if elapsed > 0 && checkedBytes > 0 {
-				bytesPerSec = float64(checkedBytes) / elapsed.Seconds()
-				remainingBytes := totalBytes - checkedBytes
-				if bytesPerSec > 0 {
-					eta = time.Duration(float64(remainingBytes)/bytesPerSec) * time.Second
+				if elapsed > 0 && checkedBytes > 0 {
+					bytesPerSec = float64(checkedBytes) / elapsed.Seconds()
+					remainingBytes := totalBytes - checkedBytes
+					if bytesPerSec > 0 {
+						eta = time.Duration(float64(remainingBytes)/bytesPerSec) * time.Second
+					}
 				}
-			}

-			sendCheckStatus(progress, CheckStatus{
-				TotalFiles:   totalFiles,
-				CheckedFiles: checkedFiles,
-				TotalBytes:   totalBytes,
-				CheckedBytes: checkedBytes,
-				BytesPerSec:  bytesPerSec,
-				ETA:          eta,
-				Failures:     failures,
-			})
+				sendCheckStatus(progress, CheckStatus{
+					TotalFiles:   totalFiles,
+					CheckedFiles: checkedFiles,
+					TotalBytes:   totalBytes,
+					CheckedBytes: checkedBytes,
+					BytesPerSec:  bytesPerSec,
+					ETA:          eta,
+					Failures:     failures,
+				})
+				lastProgressTime = now
+			}
 		}
 	}

@ -309,14 +328,13 @@ func (c *Checker) FindExtraFiles(ctx context.Context, results chan<- Result) err
 			return nil
 		}

-		// Skip manifest files
-		base := filepath.Base(rel)
-		if base == "index.mf" || base == ".index.mf" {
+		relPath := RelFilePath(rel)
+
+		// Skip the manifest file itself
+		if relPath == c.manifestRelPath {
 			return nil
 		}

-		relPath := RelFilePath(rel)
-
 		// Check if path is in manifest
 		if _, exists := c.manifestPaths[relPath]; !exists {
 			if results != nil {
--- a/mfer/checker_test.go
+++ b/mfer/checker_test.go
@ -3,6 +3,7 @@ package mfer
 import (
 	"bytes"
 	"context"
+	"fmt"
 	"testing"
 	"time"

@ -452,6 +453,61 @@ func TestCheckMissingFileDetectedWithoutFallback(t *testing.T) {
 	assert.Equal(t, 0, statusCounts[StatusError], "no files should be ERROR")
 }

+func TestFindExtraFilesSkipsDotfiles(t *testing.T) {
+	// Regression test for #16: FindExtraFiles should not report dotfiles
+	// or the manifest file itself as extra files.
+	fs := afero.NewMemMapFs()
+	files := map[string][]byte{
+		"file1.txt": []byte("in manifest"),
+	}
+	createTestManifest(t, fs, "/data/.index.mf", files)
+	createFilesOnDisk(t, fs, "/data", files)
+
+	// Add dotfiles and manifest file on disk
+	require.NoError(t, afero.WriteFile(fs, "/data/.hidden", []byte("dotfile"), 0o644))
+	require.NoError(t, fs.MkdirAll("/data/.git", 0o755))
+	require.NoError(t, afero.WriteFile(fs, "/data/.git/config", []byte("git config"), 0o644))
+
+	chk, err := NewChecker("/data/.index.mf", "/data", fs)
+	require.NoError(t, err)
+
+	results := make(chan Result, 10)
+	err = chk.FindExtraFiles(context.Background(), results)
+	require.NoError(t, err)
+
+	var extras []Result
+	for r := range results {
+		extras = append(extras, r)
+	}
+
+	// Should report NO extra files — dotfiles and manifest should be skipped
+	assert.Empty(t, extras, "FindExtraFiles should not report dotfiles or manifest file as extra; got: %v", extras)
+}
+
+func TestFindExtraFilesSkipsManifestFile(t *testing.T) {
+	// The manifest file itself should never be reported as extra
+	fs := afero.NewMemMapFs()
+	files := map[string][]byte{
+		"file1.txt": []byte("content"),
+	}
+	createTestManifest(t, fs, "/data/index.mf", files)
+	createFilesOnDisk(t, fs, "/data", files)
+
+	chk, err := NewChecker("/data/index.mf", "/data", fs)
+	require.NoError(t, err)
+
+	results := make(chan Result, 10)
+	err = chk.FindExtraFiles(context.Background(), results)
+	require.NoError(t, err)
+
+	var extras []Result
+	for r := range results {
+		extras = append(extras, r)
+	}
+
+	assert.Empty(t, extras, "manifest file should not be reported as extra; got: %v", extras)
+}
+
 func TestCheckEmptyManifest(t *testing.T) {
 	fs := afero.NewMemMapFs()
 	// Create manifest with no files
@ -473,3 +529,40 @@ func TestCheckEmptyManifest(t *testing.T) {
 	}
 	assert.Equal(t, 0, count)
 }
+
+func TestCheckProgressRateLimited(t *testing.T) {
+	// Create many small files - progress should be rate-limited, not one per file.
+	// With rate-limiting to once per second, we should get far fewer progress
+	// updates than files (plus one final update).
+	fs := afero.NewMemMapFs()
+	files := make(map[string][]byte, 100)
+	for i := 0; i < 100; i++ {
+		name := fmt.Sprintf("file%03d.txt", i)
+		files[name] = []byte("content")
+	}
+	createTestManifest(t, fs, "/manifest.mf", files)
+	createFilesOnDisk(t, fs, "/data", files)
+
+	chk, err := NewChecker("/manifest.mf", "/data", fs)
+	require.NoError(t, err)
+
+	results := make(chan Result, 200)
+	progress := make(chan CheckStatus, 200)
+	err = chk.Check(context.Background(), results, progress)
+	require.NoError(t, err)
+
+	// Drain results
+	for range results {
+	}
+
+	// Count progress updates
+	var progressCount int
+	for range progress {
+		progressCount++
+	}
+
+	// Should be far fewer than 100 (rate-limited to once per second)
+	// At minimum we get the final update
+	assert.GreaterOrEqual(t, progressCount, 1, "should get at least the final progress update")
+	assert.Less(t, progressCount, 100, "progress should be rate-limited, not one per file")
+}
--- a/mfer/deserialize.go
+++ b/mfer/deserialize.go
@ -44,7 +44,7 @@ func (m *manifest) deserializeInner() error {
 	// Verify hash of compressed data before decompression
 	h := sha256.New()
 	if _, err := h.Write(m.pbOuter.InnerMessage); err != nil {
-		return err
+		return fmt.Errorf("deserialize: hash write: %w", err)
 	}
 	sha256Hash := h.Sum(nil)
 	if !bytes.Equal(sha256Hash, m.pbOuter.Sha256) {
@ -72,7 +72,7 @@ func (m *manifest) deserializeInner() error {

 	zr, err := zstd.NewReader(bb)
 	if err != nil {
-		return err
+		return fmt.Errorf("deserialize: zstd reader: %w", err)
 	}
 	defer zr.Close()

@ -85,7 +85,7 @@ func (m *manifest) deserializeInner() error {
 	limitedReader := io.LimitReader(zr, maxSize)
 	dat, err := io.ReadAll(limitedReader)
 	if err != nil {
-		return err
+		return fmt.Errorf("deserialize: decompress: %w", err)
 	}
 	if int64(len(dat)) >= MaxDecompressedSize {
 		return fmt.Errorf("decompressed data exceeds maximum allowed size of %d bytes", MaxDecompressedSize)
@ -100,7 +100,7 @@ func (m *manifest) deserializeInner() error {
 	// Deserialize inner message
 	m.pbInner = new(MFFile)
 	if err := proto.Unmarshal(dat, m.pbInner); err != nil {
-		return err
+		return fmt.Errorf("deserialize: unmarshal inner: %w", err)
 	}

 	// Validate inner UUID
--- a/mfer/gpg.go
+++ b/mfer/gpg.go
@ -20,7 +20,7 @@ type SigningOptions struct {
 // gpgSign creates a detached signature of the data using the specified key.
 // Returns the armored detached signature.
 func gpgSign(data []byte, keyID GPGKeyID) ([]byte, error) {
-	cmd := exec.Command("gpg",
+	cmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--detach-sign",
 		"--armor",
 		"--local-user", string(keyID),
@ -42,7 +42,7 @@ func gpgSign(data []byte, keyID GPGKeyID) ([]byte, error) {
 // gpgExportPublicKey exports the public key for the specified key ID.
 // Returns the armored public key.
 func gpgExportPublicKey(keyID GPGKeyID) ([]byte, error) {
-	cmd := exec.Command("gpg",
+	cmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--export",
 		"--armor",
 		string(keyID),
@ -65,7 +65,7 @@ func gpgExportPublicKey(keyID GPGKeyID) ([]byte, error) {

 // gpgGetKeyFingerprint gets the full fingerprint for a key ID.
 func gpgGetKeyFingerprint(keyID GPGKeyID) ([]byte, error) {
-	cmd := exec.Command("gpg",
+	cmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--with-colons",
 		"--fingerprint",
 		string(keyID),
@ -114,7 +114,7 @@ func gpgExtractPubKeyFingerprint(pubKey []byte) (string, error) {
 	}

 	// Import the public key into the temporary keyring
-	importCmd := exec.Command("gpg",
+	importCmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--homedir", tmpDir,
 		"--import",
 		pubKeyFile,
@ -126,7 +126,7 @@ func gpgExtractPubKeyFingerprint(pubKey []byte) (string, error) {
 	}

 	// List keys to get fingerprint
-	listCmd := exec.Command("gpg",
+	listCmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--homedir", tmpDir,
 		"--with-colons",
 		"--fingerprint",
@ -184,7 +184,7 @@ func gpgVerify(data, signature, pubKey []byte) error {
 	}

 	// Import the public key into the temporary keyring
-	importCmd := exec.Command("gpg",
+	importCmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--homedir", tmpDir,
 		"--import",
 		pubKeyFile,
@ -196,7 +196,7 @@ func gpgVerify(data, signature, pubKey []byte) error {
 	}

 	// Verify the signature
-	verifyCmd := exec.Command("gpg",
+	verifyCmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--homedir", tmpDir,
 		"--verify",
 		sigFile,
--- a/mfer/mf.pb.go
+++ b/mfer/mf.pb.go
@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
 // 	protoc-gen-go v1.36.11
-// 	protoc        v6.33.0
+// 	protoc        v6.33.4
 // source: mf.proto

 package mfer
@ -329,6 +329,9 @@ func (x *MFFileOuter) GetSigningPubKey() []byte {
 type MFFilePath struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
 	// required attributes:
+	// Path invariants: must be valid UTF-8, use forward slashes only,
+	// be relative (no leading /), contain no ".." segments, and no
+	// empty segments (no "//").
 	Path string `protobuf:"bytes,1,opt,name=path,proto3" json:"path,omitempty"`
 	Size int64  `protobuf:"varint,2,opt,name=size,proto3" json:"size,omitempty"`
 	// gotta have at least one:
@ -337,7 +340,6 @@ type MFFilePath struct {
 	MimeType      *string    `protobuf:"bytes,301,opt,name=mimeType,proto3,oneof" json:"mimeType,omitempty"`
 	Mtime         *Timestamp `protobuf:"bytes,302,opt,name=mtime,proto3,oneof" json:"mtime,omitempty"`
 	Ctime         *Timestamp `protobuf:"bytes,303,opt,name=ctime,proto3,oneof" json:"ctime,omitempty"`
-	Atime         *Timestamp `protobuf:"bytes,304,opt,name=atime,proto3,oneof" json:"atime,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@ -414,13 +416,6 @@ func (x *MFFilePath) GetCtime() *Timestamp {
 	return nil
 }

-func (x *MFFilePath) GetAtime() *Timestamp {
-	if x != nil {
-		return x.Atime
-	}
-	return nil
-}
-
 type MFFileChecksum struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
 	// 1.0 golang implementation must write a multihash here
@ -566,7 +561,7 @@ const file_mf_proto_rawDesc = "" +
 	"\n" +
 	"_signatureB\t\n" +
 	"\a_signerB\x10\n" +
-	"\x0e_signingPubKey\"\xa2\x02\n" +
+	"\x0e_signingPubKey\"\xf8\x01\n" +
 	"\n" +
 	"MFFilePath\x12\x12\n" +
 	"\x04path\x18\x01 \x01(\tR\x04path\x12\x12\n" +
@ -576,13 +571,10 @@ const file_mf_proto_rawDesc = "" +
 	"\x05mtime\x18\xae\x02 \x01(\v2\n" +
 	".TimestampH\x01R\x05mtime\x88\x01\x01\x12&\n" +
 	"\x05ctime\x18\xaf\x02 \x01(\v2\n" +
-	".TimestampH\x02R\x05ctime\x88\x01\x01\x12&\n" +
-	"\x05atime\x18\xb0\x02 \x01(\v2\n" +
-	".TimestampH\x03R\x05atime\x88\x01\x01B\v\n" +
+	".TimestampH\x02R\x05ctime\x88\x01\x01B\v\n" +
 	"\t_mimeTypeB\b\n" +
 	"\x06_mtimeB\b\n" +
-	"\x06_ctimeB\b\n" +
-	"\x06_atime\".\n" +
+	"\x06_ctimeJ\x06\b\xb0\x02\x10\xb1\x02\".\n" +
 	"\x0eMFFileChecksum\x12\x1c\n" +
 	"\tmultiHash\x18\x01 \x01(\fR\tmultiHash\"\xd6\x01\n" +
 	"\x06MFFile\x12)\n" +
@ -627,15 +619,14 @@ var file_mf_proto_depIdxs = []int32{
 	6, // 2: MFFilePath.hashes:type_name -> MFFileChecksum
 	3, // 3: MFFilePath.mtime:type_name -> Timestamp
 	3, // 4: MFFilePath.ctime:type_name -> Timestamp
-	3, // 5: MFFilePath.atime:type_name -> Timestamp
-	2, // 6: MFFile.version:type_name -> MFFile.Version
-	5, // 7: MFFile.files:type_name -> MFFilePath
-	3, // 8: MFFile.createdAt:type_name -> Timestamp
-	9, // [9:9] is the sub-list for method output_type
-	9, // [9:9] is the sub-list for method input_type
-	9, // [9:9] is the sub-list for extension type_name
-	9, // [9:9] is the sub-list for extension extendee
-	0, // [0:9] is the sub-list for field type_name
+	2, // 5: MFFile.version:type_name -> MFFile.Version
+	5, // 6: MFFile.files:type_name -> MFFilePath
+	3, // 7: MFFile.createdAt:type_name -> Timestamp
+	8, // [8:8] is the sub-list for method output_type
+	8, // [8:8] is the sub-list for method input_type
+	8, // [8:8] is the sub-list for extension type_name
+	8, // [8:8] is the sub-list for extension extendee
+	0, // [0:8] is the sub-list for field type_name
 }

 func init() { file_mf_proto_init() }
--- a/mfer/mf.proto
+++ b/mfer/mf.proto
@ -59,7 +59,8 @@ message MFFilePath {
    optional string mimeType = 301;
    optional Timestamp mtime = 302;
    optional Timestamp ctime = 303;
-    optional Timestamp atime = 304;
+    // Field 304 (atime) removed — not useful for integrity verification.
+    reserved 304;
 }

 message MFFileChecksum {
--- a/mfer/scanner.go
+++ b/mfer/scanner.go
@ -43,11 +43,12 @@ type ScanStatus struct {

 // ScannerOptions configures scanner behavior.
 type ScannerOptions struct {
-	IncludeDotfiles bool            // Include files and directories starting with a dot (default: exclude)
-	FollowSymLinks  bool            // Resolve symlinks instead of skipping them
-	Fs              afero.Fs        // Filesystem to use, defaults to OsFs if nil
-	SigningOptions  *SigningOptions // GPG signing options (nil = no signing)
-	Seed            string          // If set, derive a deterministic UUID from this seed
+	IncludeDotfiles   bool            // Include files and directories starting with a dot (default: exclude)
+	FollowSymLinks    bool            // Resolve symlinks instead of skipping them
+	IncludeTimestamps bool            // Include createdAt timestamp in manifest (default: omit for determinism)
+	Fs                afero.Fs        // Filesystem to use, defaults to OsFs if nil
+	SigningOptions    *SigningOptions // GPG signing options (nil = no signing)
+	Seed              string          // If set, derive a deterministic UUID from this seed
 }

 // FileEntry represents a file that has been enumerated.
@ -274,6 +275,9 @@ func (s *Scanner) ToManifest(ctx context.Context, w io.Writer, progress chan<- S
 	s.mu.RUnlock()

 	builder := NewBuilder()
+	if s.options.IncludeTimestamps {
+		builder.SetIncludeTimestamps(true)
+	}
 	if s.options.SigningOptions != nil {
 		builder.SetSigningOptions(s.options.SigningOptions)
 	}
--- a/mfer/scanner_test.go
+++ b/mfer/scanner_test.go
@ -352,8 +352,10 @@ func TestIsHiddenPath(t *testing.T) {
 		{"/absolute/.hidden", true},
 		{"./relative", false}, // path.Clean removes leading ./
 		{"a/b/c/.d/e", true},
-		{".", false}, // current directory is not hidden
-		{"/", false}, // root is not hidden
+		{".", false},          // current directory is not hidden (#14)
+		{"/", false},          // root is not hidden
+		{"./", false},         // current directory with trailing slash
+		{"./file.txt", false}, // file in current directory
 	}

 	for _, tt := range tests {
--- a/mfer/serialize.go
+++ b/mfer/serialize.go
@ -34,12 +34,12 @@ func (m *manifest) generate() error {
 	}
 	dat, err := proto.MarshalOptions{Deterministic: true}.Marshal(m.pbOuter)
 	if err != nil {
-		return err
+		return fmt.Errorf("serialize: marshal outer: %w", err)
 	}
 	m.output = bytes.NewBuffer([]byte(MAGIC))
 	_, err = m.output.Write(dat)
 	if err != nil {
-		return err
+		return fmt.Errorf("serialize: write output: %w", err)
 	}
 	return nil
 }
@ -60,18 +60,18 @@ func (m *manifest) generateOuter() error {

 	innerData, err := proto.MarshalOptions{Deterministic: true}.Marshal(m.pbInner)
 	if err != nil {
-		return err
+		return fmt.Errorf("serialize: marshal inner: %w", err)
 	}

 	// Compress the inner data
 	idc := new(bytes.Buffer)
 	zw, err := zstd.NewWriter(idc, zstd.WithEncoderLevel(zstd.SpeedBestCompression))
 	if err != nil {
-		return err
+		return fmt.Errorf("serialize: create compressor: %w", err)
 	}
 	_, err = zw.Write(innerData)
 	if err != nil {
-		return err
+		return fmt.Errorf("serialize: compress: %w", err)
 	}
 	_ = zw.Close()

@ -80,7 +80,7 @@ func (m *manifest) generateOuter() error {
 	// Hash the compressed data for integrity verification before decompression
 	h := sha256.New()
 	if _, err := h.Write(compressedData); err != nil {
-		return err
+		return fmt.Errorf("serialize: hash write: %w", err)
 	}
 	sha256Hash := h.Sum(nil)

--- a/mfer/url.go
+++ b/mfer/url.go
@ -27,8 +27,12 @@ func (b BaseURL) JoinPath(path RelFilePath) (FileURL, error) {
 		base.Path += "/"
 	}

-	// Parse and encode the relative path
-	ref, err := url.Parse(url.PathEscape(string(path)))
+	// Encode each path segment individually to preserve slashes
+	segments := strings.Split(string(path), "/")
+	for i, seg := range segments {
+		segments[i] = url.PathEscape(seg)
+	}
+	ref, err := url.Parse(strings.Join(segments, "/"))
 	if err != nil {
 		return "", err
 	}
--- a/mfer/url_test.go
+++ b/mfer/url_test.go
@ -0,0 +1,44 @@
+package mfer
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestBaseURLJoinPath(t *testing.T) {
+	tests := []struct {
+		base     BaseURL
+		path     RelFilePath
+		expected string
+	}{
+		{"https://example.com/dir/", "file.txt", "https://example.com/dir/file.txt"},
+		{"https://example.com/dir", "file.txt", "https://example.com/dir/file.txt"},
+		{"https://example.com/", "sub/file.txt", "https://example.com/sub/file.txt"},
+		{"https://example.com/dir/", "file with spaces.txt", "https://example.com/dir/file%20with%20spaces.txt"},
+	}
+
+	for _, tt := range tests {
+		t.Run(string(tt.base)+"+"+string(tt.path), func(t *testing.T) {
+			result, err := tt.base.JoinPath(tt.path)
+			require.NoError(t, err)
+			assert.Equal(t, tt.expected, string(result))
+		})
+	}
+}
+
+func TestBaseURLString(t *testing.T) {
+	b := BaseURL("https://example.com/")
+	assert.Equal(t, "https://example.com/", b.String())
+}
+
+func TestFileURLString(t *testing.T) {
+	f := FileURL("https://example.com/file.txt")
+	assert.Equal(t, "https://example.com/file.txt", f.String())
+}
+
+func TestManifestURLString(t *testing.T) {
+	m := ManifestURL("https://example.com/index.mf")
+	assert.Equal(t, "https://example.com/index.mf", m.String())
+}