docs: cutting-edge search + memory research report for Flatbread + Proof

docs/research/performant-context-search/README.md

@@ -0,0 +1,19 @@
+# Performant context search research (2026)
+
+This folder documents how [`flatbread-search-and-memory-research.md`](../../../flatbread-search-and-memory-research.md) (repo root) was produced and where to find evidence **from a fresh clone**.
+
+## Methodology
+
+The report was authored using a **`/proof` DAG**: parallel subagents produced intermediate dossiers (repository audits + literature surveys), then synthesis tasks merged them into the single markdown file at the repo root.
+
+The intermediate filenames below name that pipeline only — **they are not checked into git** (doing so would duplicate hundreds of kilobytes already folded into the report and §13 references):
+
+- `audit-flatbread-retrieval.md`, `audit-proof-context.md`
+- `sota-dense-sparse-hybrid.md`, `sota-graph-structure.md`, `sota-agent-memory.md`, `sota-embeddable-runtimes.md`
+- `synthesis-flatbread.md`, `synthesis-proof.md`, `synthesis-novel.md`
+
+**Canonical sources for readers:** [`flatbread-search-and-memory-research.md`](../../../flatbread-search-and-memory-research.md), its inline citations into this repo (`packages/core`, `packages/proof`, …), and the external URLs in **§13 — References**.
+
+## Proof run artifacts
+
+When reproducing or extending this research with `@flatbread/proof`, full DAG runs write per-task transcripts under **`<cwd>/.flatbread/artifacts/`** by default. See [`packages/proof/README.md`](../../../packages/proof/README.md) (`--full-output-dir`, `--no-artifacts`).