Take the markdown fences out of the example files

[SuperInstance]

A pre-ship pass: play-test the shipped artifact end to end, clean up what it turned over, and change nothing that isn't a defect.

The one thing that needed fixing

All eight files in examples/ opened with ```plainsong and closed with ```. They are .song files, not markdown. The parser skips the fence, so nothing sounded wrong and nothing warned.

It still mattered: these files are the first thing anyone reads to learn the notation, and the failure mode observed while probing this tool with small models was an agent copying an example verbatim. What it would copy is a fence.

No music moved, and that is checked rather than claimed — the corpus fingerprint hashes the compiled arrangement, not the source, so anything audible would show. It reads 6,321 files compiling exactly as recorded, unchanged. 16 deletions, 8 files.

Play-test of the actual shipped wheel

Built plainsong-1.5.0-py3-none-any.whl, installed it into a clean venv outside the tree, and drove the documented surface — 17 commands, all passing. Then verified the outputs were real rather than trusting exit codes:

Artifact	Checked
MIDI	MThd header, 783 bytes, 63 note-on events
WAV	21.2s @ 44100Hz, peak 29162 — audible, not silence
SVG	parses as XML, 39 elements
transpose	Am→Dm moved the chord row correctly (i–VI–III–VII)
MCP	27 tools listed; deprecation on stderr; stdio stdout carries only JSON-RPC

Plus the check CI structurally cannot run, because it has no browser:

python3 tools/demo_differential.py
  6/8  triplets  3/4  sustains  rests  stacks  repeated rows  chord qualities
  all agree

Eight cases, note-for-note identical between the browser demo's own JavaScript compiler and this one.

Two things I investigated and deliberately did not change

plainsong check examples reports 3 warnings. All three are intentional:

• Two are sections whose chords stop short of the section on purpose — one is an outro literally named "fading sonar".
• The third is edge-3-dense-chords.song, whose degenerate tokens (e2-.-g2, c3--e3) are already documented in examples/edge-cases/BUGS.md as testing that they degrade gracefully to 2-note chords.

Changing any of them would alter the music to silence a warning, which is backwards.

I also chased what looked like a defect — check --json appearing to report path: None — and it was my own misreading. The key is source, and it identifies every file correctly. No change made.

Ship gate

stdlib-only (the 12 platform jobs)	705 tests, 0 errors, 0 failures
pytest	clean
specs	7/7
ruff check / format --check	clean
corpus fingerprint	6,321 files compile to identical music
verify_release.py --stage wheel	10 passed, 0 failed
browser differential	all agree

Working tree is clean — no build artifacts tracked, no stray worktrees, all caches gitignored.

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Generated by Claude Code