feat: concurrent engine execution with graceful degradation

- Run all local engines in parallel using goroutines + sync.WaitGroup
- Individual engine failures are captured as unresponsive_engines entries
  instead of aborting the entire search request
- Context cancellation is respected: cancelled engines report as unresponsive
- Upstream proxy failure is also gracefully handled (single unresponsive entry)
- Extract unresponsiveResponse() and emptyResponse() helpers for consistency
- Add comprehensive tests:
  - ConcurrentEngines: verifies parallelism (2x100ms engines complete in ~100ms)
  - GracefulDegradation: one engine fails, one succeeds, both represented
  - AllEnginesFail: no error returned, all engines in unresponsive_engines
  - ContextCancellation: engine respects context timeout, reports unresponsive
This commit is contained in:
Franz Kafka 2026-03-21 15:39:00 +00:00
parent 5181073a95
commit 385a7acab7
5 changed files with 355 additions and 35 deletions

1
go.mod
View file

@ -10,4 +10,5 @@ require (
require (
github.com/andybalholm/cascadia v1.3.3 // indirect
golang.org/x/net v0.52.0 // indirect
golang.org/x/sync v0.20.0 // indirect
)