"Is Grep All You Need?" PwC says reach for grep before vectors, then tune the harness, not the retriever.

The empirical study across Chronos plus the Claude Code, Codex, and Gemini CLI harnesses found literal grep generally beats vector retrieval on LongMemEval fact recovery. The bigger finding: accuracy swings more on which harness and tool-calling style you use than on the retrieval method. The same grep tool even scores differently depending on whether the model reads results inline or from a file. Stop assuming the embedding model is your bottleneck and start A/B testing the harness as a first-class variable.