Site crashes when many students request feedback at once

# Site crashes when many students request feedback at once

When ~12 students hit "Get feedback" simultaneously (in a single classroom), the site crashes with "upstream connection error." This is a scale issue — a single class can take the feature down.

## Reproduction

1. Have ~12 students in one class hit "Get feedback" within a short window.
2. Observe site failure with "upstream connection error."

## Expected

Concurrent feedback requests are queued or scaled so a single classroom can use the feature simultaneously. UA professor's cohort is 150+ students — must handle classroom-scale concurrency at minimum.

## Actual

Upstream connection error. Feature is unusable for that class until the spike clears.

## Impact

Hard block on classroom adoption. Any teacher using Yawp in a synchronous classroom session can trigger this. Reported 2026-03-23 during a daily-pages exercise (low-stakes context that day, but the same crash on a real essay submission would be much worse).

## Affected versions

Reported 2026-03-23. Likely been latent any time class-scale concurrency happens.

## Suspected cause

Upstream provider (LLM API) connection pool or rate limit getting saturated; no queueing or backpressure on our side. Either the API client isn't pooling properly, or we're hitting the provider's per-key concurrent-request limit.

## Workaround

Stagger requests by hand — teacher tells students to click at different times. Fragile and embarrassing.