## Summary
Fixes a regression introduced in #10941 so that heredocs do not permit
file redirects to be approved by rules, and adds scenario tests to cover
this behavior.
Previously, heredoc command parsing would allow redirects and
environment variables:
```bash
# commands_for_exec_policy() would parse this via parse_shell_lc_single_command_prefix
PATH=/tmp/bad:$PATH cat <<'EOF' > /tmp/bad/hello.txt
hello
EOF
```
This conflicts with the Codex Rules documentation; heredoc parsing logic
should abide by the same strictness of parsing.
## Tests
- [x] Updated unit tests accordingly
- [x] Added scenario tests for these cases
---------
Co-authored-by: Codex <noreply@openai.com>
## Summary
Fixes a few things in our exec_policy handling of prefix_rules:
1. Correctly match redirects specifically for exec_policy parsing. i.e.
if you have `prefix_rule(["echo"], decision="allow")` then `echo hello >
output.txt` should match - this should fix#10321
2. If there already exists any rule that would match our prefix rule
(not just a prompt), then drop it, since it won't do anything.
## Testing
- [x] Updated unit tests, added approvals ScenarioSpecs
## Summary
This should rarely, if ever, happen in practice. But regardless, we
should never provide an empty list of `commands` to ExecPolicy. This PR
is almost entirely adding test around these cases.
## Testing
- [x] Adds a bunch of unit tests for this
