Default the manifest to index.mf and keep it out of its own listing (closes #100)

mfer gen now writes index.mf instead of .index.mf, the name fetch
requests and the README calls the standard filename. Given a
directory, check, freshen, list and export look only for index.mf;
.index.mf is no longer recognized. Because index.mf is not hidden, gen
and freshen leave out of their own listing the manifest they write and
a temp file an interrupted run left beside it, matched by file
identity (os.SameFile) however the path is spelled. The scanner takes
these as a plain ExcludePaths list; manifestTempPath alone names the
temp file, for both writes, both skips and the tests.

Model: opus-5-5

internal/cli/entry_test.go

@@ -28,7 +28,6 @@ const (
 	testFile1       = "/testdir/file1.txt"
 	testMF          = "/testdir/test.mf"
 	testOutput      = "/output.mf"
-	testOutputTmp   = "/output.mf.tmp"
 	testManifest    = "/manifest.mf"
 	testFlagBase    = "--base"
 	testFlagNoExtra = "--no-extra-files"
@@ -683,7 +682,7 @@ func TestGenerateAtomicWriteNoTempFileOnSuccess(t *testing.T) {
 	assert.True(t, exists, "output file should exist")
 
 	// Verify temp file does NOT exist
-	tmpExists, err := afero.Exists(fs, testOutputTmp)
+	tmpExists, err := afero.Exists(fs, manifestTempPath(testOutput))
 	require.NoError(t, err)
 	assert.False(t, tmpExists,
 		"temp file should not exist after successful generation")
@@ -715,7 +714,7 @@ func TestGenerateAtomicWriteOverwriteWithForce(t *testing.T) {
 		"manifest should be overwritten")
 
 	// Verify temp file does NOT exist
-	tmpExists, err := afero.Exists(fs, testOutputTmp)
+	tmpExists, err := afero.Exists(fs, manifestTempPath(testOutput))
 	require.NoError(t, err)
 	assert.False(t, tmpExists,
 		"temp file should not exist after successful generation")
@@ -822,9 +821,8 @@ func TestGenerateDefaultOutputLeftOutOfListing(t *testing.T) {
 }
 
 // TestGenerateLeavesLeftoverTempFileOutOfListing runs gen where an
-// interrupted run left its temp file, index.mf.tmp, beside the output:
-// the leftover is not listed, and gen does not fail when it overwrites
-// it.
+// interrupted run left its temp file beside the output: the leftover is
+// not listed, and gen does not fail when it overwrites it.
 func TestGenerateLeavesLeftoverTempFileOutOfListing(t *testing.T) {
 	t.Parallel()
 
@@ -833,7 +831,7 @@ func TestGenerateLeavesLeftoverTempFileOutOfListing(t *testing.T) {
 
 	fs := afero.NewOsFs()
 	writeTestFile(t, fs, filepath.Join(root, testFileTxt), "hello")
-	writeTestFile(t, fs, output+".tmp", "part of a manifest")
+	writeTestFile(t, fs, manifestTempPath(output), "part of a manifest")
 
 	opts := testOpts([]string{testApp, cmdGenerate, "-q", "-o", output, root}, fs)
 	require.Equal(t, 0, runCLI(opts), "stderr: %s", testStderr(t, opts))
@@ -863,7 +861,7 @@ func TestGenerateAtomicWriteUsesTemp(t *testing.T) {
 	exists, _ := afero.Exists(fs, testOutput)
 	assert.True(t, exists, "output file should exist")
 
-	tmpExists, _ := afero.Exists(fs, testOutputTmp)
+	tmpExists, _ := afero.Exists(fs, manifestTempPath(testOutput))
 	assert.False(t, tmpExists, "temp file should be cleaned up")
 
 	// Verify manifest is valid (not empty)
@@ -929,7 +927,7 @@ func TestGenerateAtomicWriteCleansUpOnError(t *testing.T) {
 		"output file should not exist after failed generation (atomic write)")
 
 	// Temp file should also not exist
-	tmpExists, _ := afero.Exists(baseFs, testOutputTmp)
+	tmpExists, _ := afero.Exists(baseFs, manifestTempPath(testOutput))
 	assert.False(t, tmpExists,
 		"temp file should be cleaned up after failed generation")
 }

internal/cli/freshen.go

@@ -57,8 +57,7 @@ type freshenEntry struct {
 type freshenScanner struct {
 	fs              afero.Fs
 	absBase         string
-	manifestInfo    fs.FileInfo // the manifest being freshened
-	tmpInfo         fs.FileInfo // its leftover temp file; nil when there is none
+	excluded        []fs.FileInfo // files left out of the listing
 	includeDotfiles bool
 	followSymlinks  bool
 	showProgress    bool
@@ -182,11 +181,10 @@ func (s *freshenScanner) walk(path string, info fs.FileInfo, walkErr error) erro
 		info = realInfo
 	}
 
-	// Skip the manifest file itself and a temp file left beside it by an
-	// interrupted run, however their paths are spelled; gen leaves out its
-	// output file the same way. os.SameFile never matches a nil FileInfo.
-	if os.SameFile(info, s.manifestInfo) || os.SameFile(info, s.tmpInfo) {
-		return nil
+	for _, excluded := range s.excluded {
+		if os.SameFile(info, excluded) {
+			return nil
+		}
 	}
 
 	s.scanCount++
@@ -311,7 +309,7 @@ func (h *freshenHasher) processEntry(e *freshenEntry) error {
 func writeFreshenedManifest(
 	ctx context.Context, afs afero.Fs, builder *mfer.Builder, manifestPath string,
 ) error {
-	tmpPath := manifestPath + ".tmp"
+	tmpPath := manifestTempPath(manifestPath)
 
 	outFile, err := afs.Create(tmpPath)
 	if err != nil {
@@ -368,33 +366,29 @@ func (mfa *CLIApp) freshenScan(
 	startScan := time.Now()
 	showProgress := ctx.Bool("progress")
 
-	manifestInfo, err := mfa.Fs.Stat(manifestPath)
-	if err != nil {
-		return nil, 0, fmt.Errorf("freshen: %w", err)
-	}
+	// Leave out the manifest and a temp file left by an interrupted run,
+	// as gen does. A path that cannot be stat'd, normally because no file
+	// is there, needs no leaving out.
+	var excluded []fs.FileInfo
 
-	// The temp file writeFreshenedManifest writes, if an interrupted run
-	// left one. One that cannot be stat'd, normally because it does not
-	// exist, needs no leaving out.
-	var tmpInfo fs.FileInfo
-
-	info, err := mfa.Fs.Stat(manifestPath + ".tmp")
-	if err == nil {
-		tmpInfo = info
+	for _, p := range []string{manifestPath, manifestTempPath(manifestPath)} {
+		info, err := mfa.Fs.Stat(p)
+		if err == nil {
+			excluded = append(excluded, info)
+		}
 	}
 
 	scanner := &freshenScanner{
 		fs:              mfa.Fs,
 		absBase:         absBase,
-		manifestInfo:    manifestInfo,
-		tmpInfo:         tmpInfo,
+		excluded:        excluded,
 		includeDotfiles: ctx.Bool("include-dotfiles"),
 		followSymlinks:  ctx.Bool("follow-symlinks"),
 		showProgress:    showProgress,
 		existingByPath:  existingByPath,
 	}
 
-	err = afero.Walk(mfa.Fs, absBase, scanner.walk)
+	err := afero.Walk(mfa.Fs, absBase, scanner.walk)
 
 	if showProgress {
 		log.ProgressDone()

internal/cli/freshen_test.go

@@ -133,8 +133,8 @@ func TestFreshenLeavesManifestOutOfListing(t *testing.T) {
 }
 
 // TestFreshenLeavesLeftoverTempFileOutOfListing freshens a manifest where
-// an interrupted run left its temp file, index.mf.tmp, beside it: the
-// leftover is not listed.
+// an interrupted run left its temp file beside it: the leftover is not
+// listed.
 func TestFreshenLeavesLeftoverTempFileOutOfListing(t *testing.T) {
 	t.Parallel()
 
@@ -147,7 +147,7 @@ func TestFreshenLeavesLeftoverTempFileOutOfListing(t *testing.T) {
 	opts := testOpts([]string{testApp, cmdGenerate, "-q", "-o", manifestPath, root}, fs)
 	require.Equal(t, 0, runCLI(opts), "stderr: %s", testStderr(t, opts))
 
-	writeTestFile(t, fs, manifestPath+".tmp", "part of a manifest")
+	writeTestFile(t, fs, manifestTempPath(manifestPath), "part of a manifest")
 	// A new file gives freshen something to write.
 	writeTestFile(t, fs, filepath.Join(root, "added.txt"), "added")
 

internal/cli/gen.go

@@ -89,12 +89,15 @@ func (mfa *CLIApp) collectInputPaths(args cli.Args) ([]string, error) {
 
 // buildScannerOptions constructs scanner options from the CLI flags.
 func (mfa *CLIApp) buildScannerOptions(ctx *cli.Context) *mfer.ScannerOptions {
+	output := ctx.String("output")
 	opts := &mfer.ScannerOptions{
 		IncludeDotfiles:   ctx.Bool("include-dotfiles"),
 		FollowSymLinks:    ctx.Bool("follow-symlinks"),
 		IncludeTimestamps: ctx.Bool("include-timestamps"),
 		Fs:                mfa.Fs,
-		OutputPath:        ctx.String("output"),
+		// Neither a manifest being replaced nor a temp file left by an
+		// interrupted run belongs in the new manifest.
+		ExcludePaths: []string{output, manifestTempPath(output)},
 	}
 
 	// Set seed for deterministic UUID if provided
@@ -218,7 +221,7 @@ func (mfa *CLIApp) generateManifestOperation(ctx *cli.Context) error {
 	}
 
 	// Create temp file for atomic write
-	tmpPath := outputPath + ".tmp"
+	tmpPath := manifestTempPath(outputPath)
 
 	outFile, err := mfa.Fs.Create(tmpPath)
 	if err != nil {

internal/cli/mfer.go

@@ -32,6 +32,12 @@ const (
 	defaultManifestName = "index.mf"
 )
 
+// manifestTempPath returns the temp file gen and freshen write a manifest
+// to before renaming it to out.
+func manifestTempPath(out string) string {
+	return out + ".tmp"
+}
+
 // errUnknownCommand indicates an unrecognized command argument.
 var errUnknownCommand = errors.New("unknown command")
 

mfer/scanner.go

@@ -58,15 +58,8 @@ type ScannerOptions struct {
 	SigningOptions *SigningOptions
 	// Seed, if set, derives a deterministic UUID from this seed.
 	Seed string
-	// OutputPath, if set, is the file the manifest will be written to.
-	// Enumeration leaves out that file and OutputPath + ".tmp", the temp
-	// file mfer gen writes first, if they exist when the scanner is
-	// created, however their paths are spelled (through a symlink, a hard
-	// link, or in different letter case), so neither a manifest being
-	// replaced nor a temp file left by an interrupted run is ever listed.
-	// Files are matched with os.SameFile, which only recognizes files on
-	// the operating system's filesystem.
-	OutputPath string
+	// ExcludePaths lists files to leave out of the listing, matched with os.SameFile.
+	ExcludePaths []string
 }
 
 // FileEntry represents a file that has been enumerated.
@@ -85,8 +78,7 @@ type Scanner struct {
 	totalBytes FileSize // cached sum of all file sizes
 	options    *ScannerOptions
 	fs         afero.Fs
-	outputInfo fs.FileInfo // the existing output file; nil when there is none
-	tmpInfo    fs.FileInfo // its leftover temp file; nil when there is none
+	excluded   []fs.FileInfo // the files named in ExcludePaths that exist
 }
 
 // NewScanner creates a new Scanner with default options.
@@ -111,17 +103,12 @@ func NewScannerWithOptions(opts *ScannerOptions) *Scanner {
 		fs:      fs,
 	}
 
-	if opts.OutputPath != "" {
-		// A file that cannot be stat'd, normally because it does not
-		// exist, needs no leaving out.
-		info, err := s.fs.Stat(opts.OutputPath)
+	// A path that cannot be stat'd, normally because no file is there,
+	// needs no leaving out.
+	for _, p := range opts.ExcludePaths {
+		info, err := s.fs.Stat(p)
 		if err == nil {
-			s.outputInfo = info
-		}
-
-		info, err = s.fs.Stat(opts.OutputPath + ".tmp")
-		if err == nil {
-			s.tmpInfo = info
+			s.excluded = append(s.excluded, info)
 		}
 	}
 
@@ -463,10 +450,10 @@ func (s *Scanner) enumerateFileWithInfo(
 		info = realInfo
 	}
 
-	// Neither the manifest being written nor its temp file is one of the
-	// files it lists. os.SameFile never matches a nil FileInfo.
-	if os.SameFile(info, s.outputInfo) || os.SameFile(info, s.tmpInfo) {
-		return nil
+	for _, excluded := range s.excluded {
+		if os.SameFile(info, excluded) {
+			return nil
+		}
 	}
 
 	entry := &FileEntry{