f4m, ism, a bare m3u8 (native under hls_prefer_native) and the DASH generator fetch through the
proxy, but were dropped as if ffmpeg dialled them. The filter also took the job's postprocessor
hook, twice, and painted every guarded job "processing" before a byte arrived. Tests now hold an
allowed tunnel, the worker's own gate, the single-URL branch, and that the pipeline and the
backfill turn the gate on while YouTube does not.
Seen live: yt-dlp closes a connection once it has read what it needed, and the
gate printed a traceback for each. A reset ends the tunnel quietly; anything
else the gate cannot finish is a log line with its code, not bare stderr.
The URL guard judged the address the user typed; a public host's 3xx into our
network, a page's formats pointing inside, and a name rebound between the check
and the fetch all got past it, and the stored error told a live internal port
from a dead one. Every non-YouTube download now runs through an egress gate on
the worker's loopback: it resolves each host once, refuses any forbidden answer
before dialling, and connects to the address it vetted. Measured on the worker
image: yt-dlp's proxy reaches the Requests and CurlCFFI handlers, native HLS and
ffmpeg alike. Formats fetched over anything but http(s), which ffmpeg would dial
directly, are dropped, and one factory opens every yt-dlp so none skips it.
peter