Adds an opt-in search strategy toggle in the Quality Profile:
- priority (default): unchanged — first source in the hybrid chain that
meets a quality target wins.
- best_quality: pool candidates from EVERY source per query and download
them best→worst by actual audio quality; source order only breaks ties.
Implementation reuses existing plumbing so the retry system is untouched:
- engine.search_all_sources pools raw tracks across all configured,
non-exhausted sources (no first-source short-circuit).
- candidates.order_candidates: new quality_first sort path — profile
quality rank dominates, confidence/peer signals break ties. Priority
path is byte-for-byte unchanged (regression-locked by tests).
- task_worker passes quality_first + targets through; skips the redundant
hybrid-fallback block in best-quality mode (pool already covered it).
- Per-source retry budgets unchanged: a source that spends its budget is
added to exhausted_download_sources and thus dropped from the whole
pool. Independent of post_processing.retry_exhaustive.
- Query generator NOT touched.
Also clarifies the "Allow fallback" setting wording: it accepts OFF-LIST
quality as a last resort (not "walk down my list"), and notes that
lossy_copy.downsample_hires also bypasses the quality gate — the cause of
16-bit/MP3 files slipping through a 24-bit-only profile.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Add core/quality/selection.py: rank_with_targets() returns (ranked,
satisfied) where satisfied = a candidate meets a real target (strict).
load_profile_targets()/rank_for_profile() are the DB-backed wrappers.
search_with_fallback now skips a source that can deliver no target-meeting
quality and escalates to the next (source priority still wins among
satisfying sources; first source's results kept as fallback unless the
profile disables it). Returns RAW tracks — the satisfied check is a coarse
source gate; match-filtering + final ranking stay in the orchestrator so
the correct track is never pruned. Ranking is fail-open: a ranking error
never drops a source's real results.
Tested: rank_with_targets satisfied/fallback matrix + engine escalation,
stop-on-first, raw-not-pruned, fallback on/off. Amazon field test updated
for the corrected format token.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
