LowFile-scopePython Plug & play

Use list comprehensions and avoid redundant sorting

Prefer comprehensions over map/filter chains and avoid double-sorting or sorting inside loops.

Why this matters

Improves readability and avoids unnecessary allocations/time.

Side-by-side examples engineers can pattern-match during review.

Avoid

result = list(map(f, filter(pred, xs)))
for _ in range(3): xs = sorted(xs)

Prefer

result = [f(x) for x in xs if pred(x)]
xs = sorted(xs)  # once, outside loops

Bad

sorted(sorted(xs))

Good

xs = sorted(xs, key=key)

From the same buckets as this rule.

Critical
Avoid Blocking Calls to Async Methods
Blocking async methods with `.Result` or `.Wait()` can cause deadlocks and prevent efficient asynchronous execution. Use `await` instead for proper async behavior.
concurrency-safetyperformance-efficiency
Critical
Fingerprint assets and cache immutably
All static JS/CSS/font/image files MUST use content-hashed filenames (e.g., app.9c1a7b.js) and be served with "Cache-Control: public, max-age=31536000, immutable". HTML and other non-fingerprinted documents MUST be served with "Cache-Control: no-cache" (or equivalent) to enable conditional revalidation.
web-static-assetscaching-strategy+2
Critical
No live network or DB in unit tests—use fakes/mocks
Unit tests must stub or fake external HTTP/DB calls; allow real I/O only in integration/e2e tests tagged accordingly.
testing-qualityperformance-efficiency+1