fix(practice): draw the first Practice problem at the unlocked level (#21)

[tsenoner]

Closes #21.

First issue off the post-Levels roadmap — picked first because it's the only live bug and it directly protects the just-shipped Levels feature.

The bug

useUnlockedLevel() resolved meta.unlockedLevel into a ref asynchronously, but useDrill/useGuided seed problem #1 synchronously in their useState initializer — when the ref is still 0. Now that level tests write meta.unlockedLevel, a user who unlocked a wider range got a level-0 first problem every session (only problem #2 onward respected the unlocked level). Latent until #13 shipped; live now.

The fix

• useUnlockedLevel() now returns { ref, level, loaded } — the live ref for imperative next-problem reads, plus the resolved level + a loaded flag.
• useDrill/useGuided keep the lazy seed for first paint and add a once-guarded effect that regenerates problem fix: address baseline code-review findings #1 when the level resolves — only if it differs from the seed (skips level === 0, so default users never see a swap) and only while the first problem is still untouched. The draw happens outside the state updater (StrictMode-safe).
• useSpeedrun only consumes the ref (its first problem is generated in the user-triggered start(), after the read resolves) — left unchanged.

Tests

• New useDrill/useGuided specs assert the redraw at the unlocked level and the no-swap guard at level 0 — strengthened to assert call count + problem-object identity (a weaker first cut false-passed; an adversarial review caught it and a mutation test now confirms removing the level === 0 guard makes the no-swap test fail).
• useUnlockedLevel test updated for the new { ref, level, loaded } shape.

Verification

• typecheck ✓ · lint --max-warnings 0 ✓ · 290 tests ✓ · build ✓
• Adversarial review of the diff: 7 candidates → all the same test-quality finding (now fixed) → re-verified clean via mutation testing.

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
daycipher	Ready	Preview, Comment	Jun 23, 2026 10:16am