The expression check

A self-audit, not a gate (RULES.md #4) — nothing here locks or unlocks anything. It's an honest look at whether Stage 7's ground is solid before Stage 8b (reading in position) and the Intermediate gate. One item on this list — vibrate on a sustained note — is a criterion of that gate.

What Stage 7 asked of you

1 · Vibrate on a sustained note — and control it. Not just "can you wobble," but: start it from a straight note, stop it deliberately, widen it, narrow it. The switch, not just the motion.

2 · Vibrate on every finger and every string, evenly enough. Especially the 4th finger and the G and E strings — the ones it's tempting to skip.

3 · Shape a phrase with time, not only with the bow. An agogic lean on the right note; a small rubato into a peak and back; a breath at the phrase end. The bow-shaping was Stage 5; this is the layer on top.

4 · Choose a tone colour for a character and produce it. Play a phrase sul tasto for a memory, near the bridge for an arrival — on purpose, not by accident.

5 · Name a piece's character in one word, and make it audible. "Lament." "March." Then three concrete choices that a listener could hear.

6 · Make about five expressive choices about a tune, and repeat them. The same performance three times running — deliberate, not improvised.

7 · Play a Classical phrase in Classical style. Narrow vibrato, little rubato, non-legato default, contained dynamic — and still shaped, not dead.

Check yourself

Where this leaves you

If most of that felt solid, you have the expressive layer — the thing that turns correct notes into music, and the fifth of PRD.md §3's capabilities (Choose). Ahead: Stage 8b — reading fluently in the positions Stage 6 opened — and then the Intermediate gate, whose vibrato criterion you've just met.

Vibrato is the one skill in this course that most needs a real teacher's eye. If you can, have an experienced player watch your hand once. A written description can't tell you whether your thumb is quietly cheating.