Merge nucleic/sleek-thistle-egret-fyej into dev

README.md

@@ -0,0 +1,19 @@
+# shell/ — nash, the Nucleic agent shell
+
+Design doc: [docs/NASH.md](../docs/NASH.md). Vendored fork base:
+[`third_party/brush/`](../third_party/brush/) (brush, pinned at
+`brush-shell-v0.4.0`; fork patches are marked with `// nash:` comments).
+
+- `nash/` — the shell binary (M0: transparent embedding of the brush CLI).
+- `nash-observe/` — event model, taps, and transport (lands in M1).
+- `corpus/` — transcript-replay compat harness: `replay.py` runs every command
+  in `corpus.jsonl` under bash and nash in identical fresh workspaces and diffs
+  exit/stdout/filesystem (stderr reported separately). Divergences are tracked
+  in `corpus/DIVERGENCES.md`.
+
+Build & test:
+
+```sh
+cargo build --release                      # binary: target/release/nash
+python3 corpus/replay.py --nash <path>     # M0/M3 gate: >= 99% parity
+```