Anti-Pattern Grep Library

Consolidated grep patterns for automated scanning. Run these with the Grep tool using type: "cs" filter.

All patterns use ripgrep regex syntax. Run during Phase 1 (Discovery) broad scan.

See also: each topic catalog (critical-patterns.md, async-patterns.md, memory-and-strings.md, collections-and-linq.md, regex-patterns.md, io-and-serialization.md, structural-patterns.md) has its own Detection section with topic-specific recipes and ratio-counting guidance. This file is the consolidated cross-cutting library; load topic files when their signals are present.

ASYNC anti-patterns (CRITICAL)

\.Result\b
\.Wait\(\)
\.GetAwaiter\(\)\.GetResult\(\)
async void\b
Task\.Run\(
\.WriteAsync\([^,]*\)

False positive note: .Result matches Task.FromResult -- verify actual blocking before flagging.

Memory anti-patterns (MEM)

new byte\[\d{4,}\]
new byte\[
new MemoryStream\(\)
\.Substring\(
new StringBuilder\(\)
new List<.*>\(\)
new Dictionary<.*>\(\)
_logger\.Log(Debug|Trace|Information|Warning|Error|Critical)\(\$"
\.Split\(

LINQ anti-patterns

\.Count\(\)\s*[><=!]
\.ToList\(\)\.Where\(
\.ToList\(\)\.Select\(
\.Select\(.*\)\.Where\(
\.OrderBy.*\.Where\(

Database / CosmosDB anti-patterns (DB)

\.Include\(.*\.Include\(
await.*foreach.*await.*Async
ReadItemAsync
GetItemQueryIterator
GetItemLinqQueryable
\.RequestCharge

JSON anti-patterns

new JsonSerializerOptions
new JsonSerializerSettings
JsonConvert\.Serialize
JsonConvert\.Deserialize
new JsonSerializer

Caching anti-patterns (CACHE)

GetAsync\(
SendAsync\(
_cache\.TryGetValue
DistributedCache
AddMemoryCache\(\)

HttpClient misuse (HTTP)

new HttpClient\(
new HttpClient\b

Exception control flow (EXC)

catch\s*\(Exception\b
catch\s*\(KeyNotFoundException
catch\s*\(FormatException
catch\s*\(InvalidOperationException

String anti-patterns (STR)

\+= "
\+= \$"
\.ToLower\(\)
\.ToUpper\(\)
String\.Format\(

Concurrency anti-patterns (CONC)

lock\s*\(
new SemaphoreSlim
HttpContext.*Task\.Run

Startup & Pipeline (STARTUP)

UseResponseCompression
AddResponseCompression
ShortCircuit
AddOutputCache
UseOutputCache
TieredPGO
PublishReadyToRun
ApplicationStarted

Metrics & Observability (METRICS)

new Meter\(
CreateCounter
CreateHistogram
AddMeter

CancellationToken coverage

async Task[<\s].*\)\s*$

This pattern finds async methods whose signature ends without a CancellationToken parameter. Verify each match -- some may be interface implementations where the token is propagated differently.

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