## Why
Reviewing a shortened `write_stdin` action while sending the complete input could allow unreviewed bytes to reach an escalated terminal.
## What changed
- Require the fully formatted action and approval reason to fit within 8,000 bytes.
- Reject truncated or oversized actions before requesting approval or writing any bytes to the terminal.
- Document the reviewed stdin size limit in the app-server protocol.
## Testing
Add an integration test that uses JSON escaping to push a formatted action over the limit and verifies that it is neither offered for approval nor executed, while a subsequent valid write still succeeds.
GitOrigin-RevId: f6c96a78a65a136366c8119a7d242dfc2ec05fe6