Replies no longer point you at files you can't open
When the agent's reply on Linear or GitHub mentions a file that only exists in its sandbox, Sinatra attaches the file's contents or says it wasn't delivered.
Before this, an agent could finish with "the report is in /tmp/report.md" and leave you with nothing to read, because the sandbox is private to the run. Small text files are now attached under the reply, up to five files, each under 20 KB and about 40 KB in all. Binary files, larger files, anything that looks like a credential, and symlinks that lead outside the sandbox's working folders are not attached, and the reply says which ones were left behind. Files tracked in the repository are left alone, including ones the agent edited but didn't push, so a summary that names the code it changed doesn't paste that code into the comment. PR descriptions and comments the agent posts itself while it works aren't checked; for those we rely on the agent's instructions, which now tell it to put documents in its reply or commit them.
#1468