Try to prevent what could lead to execution of embedded jinja in original files when converting

README.md

@@ -115,9 +115,8 @@ ERB mode the file is intended to be Puppet Hiera data rather than Ansible role
 defaults.
 
 JinjaTurtle does **not** generate Puppet classes or `file` resources. A Puppet
-module, or another tool such as Enroll, should still declare the class
-parameters and call the template, for example with Puppet's `template()`
-function.
+module, should still declare the class parameters and call the template, for
+example with Puppet's `template()` function.
 
 ## Using `--puppet-class`
 
@@ -340,15 +339,53 @@ JinjaTurtle also templates some common bespoke config formats:
 For ambiguous extensions like `*.conf`, JinjaTurtle uses lightweight content
 sniffing. You can always force a specific handler with `--format`.
 
-## Relationship with Enroll
+## Security model
 
-JinjaTurtle can be used directly, but it is also useful as a helper for tools
-that generate configuration-management code.
+JinjaTurtle is frequently pointed at config files that were *harvested* from
+real systems, where some content may be influenced by an untrusted party (a
+hostname, a login banner, a `GECOS` comment, a "Managed by ..." note). It is
+therefore designed so that source content cannot turn into executable template
+code.
+
+Two guarantees matter:
+
+1. **Values are data, never code.** Every config *value* is replaced with a
+   `{{ variable }}` placeholder in the template, and the original value is stored
+   separately in the defaults/Hiera data. When the template is later rendered,
+   the placeholder prints the value as a literal string; Jinja2 does not
+   recursively render the *contents* of a variable, so a payload sitting inside
+   a value (for example `motd = {{ salt['cmd.run']('id') }}`) is inert.
+
+2. **Verbatim text is neutralised.** To preserve formatting, JinjaTurtle copies
+   comments, blank lines, headers and any unrecognised lines from the source
+   into the template. Any template metacharacters in that copied text
+   (`{{ }}`, `{% %}`, `{# #}` for Jinja2; `<% %>` for ERB) are escaped so they
+   render as the literal characters the author wrote, rather than executing.
+
+### Consumer responsibilities
+
+The value guarantee above relies on the downstream renderer being single-pass,
+which is the normal case:
+
+- **Ansible**: rendering a template with `template:`/`ansible.builtin.template`
+  is single-pass. For defence in depth, treat the generated defaults as
+  untrusted input — Ansible already does not re-template variable *contents* by
+  default. If you build your own var structures from this data and pass them
+  through additional templating, mark untrusted values with the `!unsafe` tag so
+  they are never re-evaluated.
+- **Salt**: use the generated file as a `file.managed` template
+  (`template: jinja`). Do **not** place JinjaTurtle output where Salt would
+  render it a second time as part of SLS/pillar rendering, which is a separate
+  Jinja pass and would re-evaluate any embedded expressions.
+- **Puppet/ERB**: render with the standard `template()`/`epp()` flow.
+
+In short: render JinjaTurtle output exactly once. Do not feed it back through
+another templating pass.
+
+**IMPORTANT**: Always review both the original config files, then the resulting
+templates generated by JinjaTurtle, before integrating them into your config
+management system!
 
-Enroll can call JinjaTurtle when it is available on the `PATH`. In that setup,
-Enroll decides where Puppet, Ansible, or Salt files belong, while JinjaTurtle
-concentrates on converting harvested config files into templates plus variable
-data.
 
 ## Found a bug, have a suggestion?