Originally Posted by
dave_261
For clarity, does inbound F on the AA JFK-DOH flight, connecting to QR J DOH-SIN (no first class offered), permit Al Safwa access? Or, only inbound F over 5 hours on QR metal?
For clarity, yes

As stated above, and in many other posts, the latest version of the rules means that an arrival in first sprinkles F-dust over your connection, regardless of subsequent class of travel.
(things only turn awkward if that connection breaches midnight and lasts too long into the following day …. in which the rule-book might banish you to Mourjan)