Credence.Pattern.NoRedundantAssignment (credence v0.6.0)

Detects a variable (or tuple/list of plain variables) being assigned and immediately returned as the last two statements of a block.

This is a common LLM verbosity pattern where the assignment adds no value. In Elixir, the last expression in a block is its return value, so the intermediate binding is unnecessary.

Tier 1 — simple variable

# Bad
result = compute(x)
result

# Good
compute(x)

Tier 2 — tuple/list of plain variables

# Bad
{a, b} = process(input)
{a, b}

# Good
process(input)

Patterns containing literals (e.g. {:ok, result}) are NOT fixed because the match acts as an assertion — removing it would change error behavior. Map patterns are never fixed because reconstruction produces a subset.

Auto-fix

Replaces the last two statements with just the RHS of the assignment.