Reject invalid secret names before any command builds a path (closes #33)

`secret rm ..` resolved to the vault directory and deleted the whole
vault; `secret rm .` and `secret rm ""` deleted every secret. rm, mv,
the version commands, encrypt and decrypt built paths from the name
without checking it; import checked it only after reading the source
file.

vault.ValidateSecretName wraps the existing name rule; its error and
README.md state the rule. Each of those commands calls it on the name
as given, before building any path; MoveSecret checks both names once,
for every form of the move, before switching the current vault.
AddSecret, GetSecretVersion and GetSecretObject use it too.

The regression test copies two in-memory vaults for each rejected
command and requires the exact error and an unchanged state directory.

Model: opus-5-5

README.md

@@ -113,7 +113,9 @@ automatically switch to another vault if removing the current one.
 Adds a secret to the current vault. Reads the secret value from stdin.
 - `--force, -f`: Overwrite existing secret
 
-**Secret Name Format:** `[a-z0-9\.\-\_\/]+`
+**Secret Name Format:** only letters, digits, `.`, `-`, `_` and `/` are
+allowed, and a name must not be empty, start with `.` or `/`, end with `/`,
+contain `//`, or have `..` as a path segment.
 - Forward slashes (`/`) are converted to percent signs (`%`) for storage
 - Examples: `database/password`, `api.key`, `ssh_private_key`
 

TODO.md

@@ -30,7 +30,7 @@ Bring the repo into policy compliance in one commit:
   nothing when it is invalid: `rm`, `mv` (both names, within a vault
   and between vaults, before switching the current vault), `import`,
   `version list`/`promote`/`rm`, `encrypt` and `decrypt`. The error
-  states the naming rule. Before, `secret rm ..` deleted the whole
+  and `README.md` state the naming rule. Before, `secret rm ..` deleted the whole
   vault and `secret rm .` every secret in it.
 - 2026-10-02: A plain `docker build .` builds again: the size tests
   skip a case that needs more locked memory than the process can

internal/cli/secrets.go

@@ -712,13 +712,8 @@ func (cli *Instance) MoveSecret(
 	srcVaultName, srcSecretName, srcQualified := ParseVaultSecretRef(source)
 	destVaultName, destSecretName, destQualified := ParseVaultSecretRef(dest)
 
-	// If neither is qualified, this is a simple within-vault rename
-	if !srcQualified && !destQualified {
-		return cli.moveSecretWithinVault(cmd, srcSecretName, destSecretName, force)
-	}
-
 	// Cross-vault move requires source to be qualified
-	if !srcQualified {
+	if !srcQualified && destQualified {
 		return errCrossVaultSourceUnqualified
 	}
 
@@ -726,29 +721,27 @@ func (cli *Instance) MoveSecret(
 	// Format: "work:secret default" means move to vault "default"
 	// Format: "work:secret default:newname" means move to vault "default"
 	// with a new name
-	if !destQualified {
+	if srcQualified && !destQualified {
 		// Check if dest is actually a vault name
 		vaults, err := vault.ListVaults(cli.fs, cli.stateDir)
 		if err == nil && slices.Contains(vaults, dest) {
 			// dest is a vault name, use source secret name
 			destVaultName = dest
 			destSecretName = srcSecretName
-		}
-
-		// If destVaultName is still empty, dest is a secret name in source vault
-		if destVaultName == "" {
+		} else {
+			// dest is a secret name in source vault
 			destVaultName = srcVaultName
-			destSecretName = dest
 		}
 	}
 
-	// If destination secret name is empty, use source secret name
-	if destSecretName == "" {
+	// If destination secret name is empty, use source secret name. A plain
+	// rename keeps it empty, so that the check below rejects it.
+	if srcQualified && destSecretName == "" {
 		destSecretName = srcSecretName
 	}
 
-	// Check both names before selecting a vault below, so that a rejected
-	// move leaves the current vault as it was.
+	// Check both names, for every form of the move, before selecting a vault
+	// below, so that a rejected move leaves the current vault as it was.
 	err := vault.ValidateSecretName(srcSecretName)
 	if err != nil {
 		return err
@@ -759,6 +752,11 @@ func (cli *Instance) MoveSecret(
 		return err
 	}
 
+	// If neither is qualified, this is a simple within-vault rename
+	if !srcQualified && !destQualified {
+		return cli.moveSecretWithinVault(cmd, srcSecretName, destSecretName, force)
+	}
+
 	// Same vault? Use simple rename if possible (optimization)
 	if srcVaultName == destVaultName {
 		// Select the vault and do a simple move
@@ -775,20 +773,11 @@ func (cli *Instance) MoveSecret(
 		cmd, srcVaultName, srcSecretName, destVaultName, destSecretName, force)
 }
 
-// moveSecretWithinVault handles rename within the current vault
+// moveSecretWithinVault handles rename within the current vault. Its caller,
+// MoveSecret, has already checked both secret names.
 func (cli *Instance) moveSecretWithinVault(
 	cmd *cobra.Command, source, dest string, force bool,
 ) error {
-	err := vault.ValidateSecretName(source)
-	if err != nil {
-		return err
-	}
-
-	err = vault.ValidateSecretName(dest)
-	if err != nil {
-		return err
-	}
-
 	currentVlt, err := vault.GetCurrentVault(cli.fs, cli.stateDir)
 	if err != nil {
 		return err