secret list gives each secret's own creation and last-update times (closes #142)

secret list and secret list --json gave the time of the listing as every
secret's creation and last-update time, because Secret.LoadMetadata set
both to the current time. It now reads file modification times, so
listing still needs no passphrase: the last update is when the secret's
current file was written, and the creation is when its oldest version's
value.age was written. A move to another vault gives the copied files
the times of the originals.

GetSecretObject no longer loads the times, so secret get keeps its error
for a missing current file; secret list calls LoadMetadata itself.

Judgement call: the creation time comes from value.age, not from the
oldest version's directory, whose time changes when the next add
rewrites that version's metadata.age.

Model: opus-5-5

internal/vault/secrets.go

@@ -427,7 +427,8 @@ func (v *Vault) UnlockVault() (*age.X25519Identity, error) {
 	return longTermIdentity, nil
 }
 
-// GetSecretObject retrieves a Secret object with metadata loaded from this vault
+// GetSecretObject retrieves a Secret object from this vault. Its times are
+// zero until its LoadMetadata reads them.
 func (v *Vault) GetSecretObject(name string) (*secret.Secret, error) {
 	err := ValidateSecretName(name)
 	if err != nil {
@@ -454,16 +455,7 @@ func (v *Vault) GetSecretObject(name string) (*secret.Secret, error) {
 		return nil, fmt.Errorf("secret %s %w", name, ErrSecretNotFound)
 	}
 
-	// Create a Secret object
-	secretObj := secret.NewSecret(v, name)
-
-	// Load the metadata from disk
-	err = secretObj.LoadMetadata()
-	if err != nil {
-		return nil, err
-	}
-
-	return secretObj, nil
+	return secret.NewSecret(v, name), nil
 }
 
 // CopySecretVersion copies a single version from source into destSecretDir
@@ -581,8 +573,8 @@ func (v *Vault) CopySecretAllVersions(
 	}
 
 	// Copy each version and the current pointer, then move the copy into place
-	err = v.copyVersions(srcVault, srcIdentity,
-		srcSecretName, destSecretName, destSecretDir, versions, currentVersion)
+	err = v.copyVersions(srcVault, srcIdentity, srcSecretName, srcSecretDir,
+		destSecretName, destSecretDir, versions, currentVersion)
 	if err != nil {
 		return err
 	}
@@ -801,10 +793,13 @@ func (v *Vault) createAndSaveVersion(
 // pointer into a temporary directory, then moves that directory to
 // destSecretDir, replacing a secret already there. Nothing in this vault
 // changes until the copy is complete, so an interrupted copy leaves only a
-// temporary directory behind.
+// temporary directory behind. Each copied value.age and current file gets
+// the modification time of the file it was copied from, so `secret list`,
+// which reads a secret's times from them, lists the copy with the times of
+// the source.
 func (v *Vault) copyVersions(
 	srcVault *Vault, srcIdentity *age.X25519Identity,
-	srcSecretName, destSecretName, destSecretDir string,
+	srcSecretName, srcSecretDir, destSecretName, destSecretDir string,
 	versions []string, currentVersion string,
 ) error {
 	buildDir, err := secret.TempDirFor(v.fs, destSecretDir)
@@ -823,6 +818,14 @@ func (v *Vault) copyVersions(
 		if err != nil {
 			return fmt.Errorf("failed to copy version %s: %w", versionName, err)
 		}
+
+		valuePath := filepath.Join("versions", versionName, "value.age")
+
+		err = copyModTime(srcVault.fs, filepath.Join(srcSecretDir, valuePath),
+			v.fs, filepath.Join(buildDir, valuePath))
+		if err != nil {
+			return err
+		}
 	}
 
 	err = secret.SetCurrentVersion(v.fs, buildDir, currentVersion)
@@ -830,6 +833,12 @@ func (v *Vault) copyVersions(
 		return fmt.Errorf("failed to set current version: %w", err)
 	}
 
+	err = copyModTime(srcVault.fs, filepath.Join(srcSecretDir, "current"),
+		v.fs, filepath.Join(buildDir, "current"))
+	if err != nil {
+		return err
+	}
+
 	// With --force, the secret being replaced goes only now that its
 	// replacement is complete
 	exists, err := afero.DirExists(v.fs, destSecretDir)
@@ -854,6 +863,26 @@ func (v *Vault) copyVersions(
 	return nil
 }
 
+// copyModTime gives destPath in destFs the modification time of srcPath in
+// srcFs.
+func copyModTime(
+	srcFs afero.Fs, srcPath string, destFs afero.Fs, destPath string,
+) error {
+	info, err := srcFs.Stat(srcPath)
+	if err != nil {
+		return fmt.Errorf("failed to read modification time of %s: %w",
+			srcPath, err)
+	}
+
+	err = destFs.Chtimes(destPath, info.ModTime(), info.ModTime())
+	if err != nil {
+		return fmt.Errorf("failed to set modification time of %s: %w",
+			destPath, err)
+	}
+
+	return nil
+}
+
 // checkCopyDestination refuses to copy over an existing secret unless force
 // is set. A secret being replaced is removed by copyVersions, once its
 // replacement is complete.