test(playback): fuzz the note renderer for stuck notes under seek/loop stress#6453
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…p stress Drive ArrangementNoteRenderer through 8 fixed-seed x 600-op randomized seek / set_loop / set_playing sequences (with random block sizes) over a document of overlapping sustained, short, and retriggering notes, then assert the physical MIDI stream never leaks a note: a per-key on/off toggle invariant every block, plus a terminal stop-flush that must leave has_active_notes() == false with every note-on matched by a note-off. Randomness is deterministic (std::mt19937 over hardcoded seeds, never random_device) so CI is reproducible; a red on any seed is a real stuck-note defect, not a flake. Aggregate non-vacuity witnesses assert the run actually exercised the risky paths (notes held live across seeks and loop wraps), so the final all-clear cannot be a vacuous green. Documents the fuzz coverage and its invariant in the playback skill's Validation section. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01TVQHcnbg3t6TvXsdv6gXhS
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Phase-2 DoD Proof #4: no stuck notes under randomized seek/loop stress.
What
Adds one fuzz case to the already-registered
test_playback_note_renderer.cpp(targetpulp-test-playback-note-renderer) that drivesArrangementNoteRendererthrough 8 fixed-seed x 600-op randomizedseek/set_loop/set_playingsequences (with random block sizes) over a document of overlapping sustained, short, and retriggering notes.Invariant asserted
has_active_notes()must be false and every note-on matched by a note-off (per seed).Reproducible, non-vacuous
std::mt19937over hardcoded seeds, neverrandom_device. A red on any seed is a real stuck-note defect, not a flake.> 0) prove the risky paths were exercised:saw_active_blocks=1445,seeks_over_active_notes=186(seeked out of sounding notes),loop_wrap_blocks=205,loop_wrap_over_active=61(wrapped a loop while notes were live).REQUIRE_FALSE(renderer.has_active_notes()).Validation
pulp-test-playback-note-renderer— 22709 assertions in 15 test cases, all passed (Release).gates.sh origin/mainclean; skill-sync + docs-noise + version-bump (no bump needed) all pass. Documents the fuzz coverage in theplaybackskill's Validation section.🤖 Generated with Claude Code
https://claude.ai/code/session_01TVQHcnbg3t6TvXsdv6gXhS
🔎 Provenance
claudem3/Volumes/Workshop/Code/pulp-proof4c66f4a64-25ea-42e5-b184-d48611a066a2Resume
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Restore URL — https://claude.ai/code/session_01TVQHcnbg3t6TvXsdv6gXhS
stamped 2026-07-22 03:25 UTC