Preserve inbound attachment/sticker metadata in Discord message context when media download fails (for example due to SSRF blocking), so agents still see file references instead of silent drops.
Closes#28816
* fix(discord,slack): add SSRF policy for media downloads in proxy environments
Discord and Slack media downloads (attachments, stickers, forwarded
images) call fetchRemoteMedia without any ssrfPolicy. When running
behind a local transparent proxy (Clash, mihomo, Shadowrocket) in
fake-ip mode, DNS returns virtual IPs in the 198.18.0.0/15 range,
which the SSRF guard blocks.
Add per-channel SSRF policy constants—matching the pattern already
applied to Telegram on main—that allowlist known CDN hostnames and
set allowRfc2544BenchmarkRange: true.
Refs #25355, #25322
Co-authored-by: Cursor <cursoragent@cursor.com>
* chore(slack): keep raw-fetch allowlist line anchors stable
---------
Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>
