2026.09.06-cbeb3eb6c

line_coverage_floor: lower lfetch.c to its true measured minimum (#390)

Decomposed lfetch.c's line coverage across ~50 serial MODE=cov runs:
it is a fixed base of 579 always-executed lines plus up to 16 lines
split across four independent, all-or-nothing branches -- a TLS
socket-read error path, FetchStreamRead's TLS body-read path (which
only fires when the streaming test's real external HTTPS fetch
succeeds), and two code paths for a chunked response whose final
chunk and terminator land in the same read vs. two. Every observed
local value (586, 588, 590, 592) and the CI-observed 582 fit this
model exactly as base plus some subset of the four, so 579 -- base
with none of them firing -- is the true minimum, not an estimate,
and the previous 585 floor sat inside that range rather than below
it. The comment now derives the number instead of guessing a margin.


Claude-Session: https://claude.ai/code/session_01HrDAg7zGvuPZuechv2xuEJ

Co-authored-by: Claude <noreply@anthropic.com>