Add text parameter type; verify commands run in the owning repo root

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: sonnet
Assistant-Process: 295952@bnt-lap001
Assistant-Session: e93f64ad-516c-46eb-9666-aad8d300c477

docs/pack-spec.md

@@ -26,7 +26,10 @@ under any root given on the command line.
 ## Parameters
 
 Each parameter has `id` (`[a-z][a-z0-9_]*`), `label`, `type`
-(`string|enum|path|bool|int`), optional `values`, `default`, `pattern`, `help`.
+(`string|text|enum|path|bool|int`), optional `values`, `default`, `pattern`, `help`.
+`text` is single-line free text for use inside double quotes: spaces are allowed and
+shell metacharacters (`; & | ` $ < > \ ' "`) are not. Every other type also rejects spaces.
+
 **`secret` may only be `false`**: a parameter is never a secret. Steps refer to
 parameters as `{{id}}`. An undefined placeholder, an unused parameter, an
 `enum` without `values`, or a default that violates its `pattern`/`values` is a
@@ -48,6 +51,9 @@ enabled for that step), `risk` (`read-only|changes-state|attended|destructive`),
 A step with `risk` of `changes-state`, `attended` or `destructive` must state a
 `rollback` (which may say "not reversible" and why).
 
+Commands are relative to the root of the repository that owns the pack. Verify
+commands run there, so a pack can call `make` targets and repo-relative scripts.
+
 ## Exercise status
 
 Following the attended-procedure standard, a pack is `unexercised` until an