Reading real clustered output caught a config error the tests could not:
Ohio Capital Journal and Kentucky Lantern are both States Newsroom outlets
syndicating the same national desk, and carried 10 byte-identical headlines in a
single poll -- more than any other source pair. Configured as separate buckets
they would have doubled the corroboration signal on every syndicated story,
which is exactly the failure the bucket concept exists to prevent.
Found by checking identical headlines across all source pairs rather than
spot-fixing the one noticed by eye. That sweep also confirmed the buckets
already set deliberately are right: BBC Top/World, Ars Technica/Science and
NPR News/Politics each share a bucket and each showed shared headlines.
Regression test added.
Pipeline: fetch -> normalise -> embed (CPU) -> cluster. `news poll` runs a
cycle; `news sources` and `news clusters` inspect the result. Replay and the
live service share run_cycle so tuning and production cannot diverge -- the old
system's replay harness hardcoded default params and could never sweep the
thresholds it existed to tune.
Calibrated, not guessed:
- Cluster threshold 0.82, from reading real output. 0.70 merged "Solheim Cup
capsules" with "FIBA Women's World Cup Glance"; 0.82 gives clean groups (76
items on the AfD Saxony-Anhalt election, 27 on the Nepal tunnel rescue). The
old system produced 515 clusters of which 514 were singletons.
- Corroboration counts DISTINCT buckets, not feeds, so ten outlets reprinting
one wire story is one confirmation rather than ten.
Removed after measurement: a SimHash near-duplicate stage. It gave +1.2 bits of
separation on titles and -0.2 with summaries -- news duplicates are paraphrases,
which is the same lexical trap that sank the old Jaccard clustering.
Sources: all 39 fetched against the live web, not assumed. Dropped CBC (every
feed URL times out from this host) and Tech Policy Press (serves HTML at every
documented feed path). Fixed WVXU (index.rss is an empty stub; local-news.rss
works). Reddit moved to .rss because .json now 403s without OAuth, and its
intervals raised because it 429s after three quick requests. Deutsche Welle is
back: it ships RSS 1.0/RDF, which feedparser reads and the old hand-rolled
quick-xml parser could not.
connor