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

NUCLEIC_FORK.md

@@ -0,0 +1,21 @@
+# Nucleic fork of brush
+
+Vendored copy of [reubeno/brush](https://github.com/reubeno/brush), pinned at
+tag **`brush-shell-v0.4.0`** (upstream commit `96a26d0`), consumed by the
+`shell/` workspace to build **nash**, the Nucleic agent shell
+([docs/NASH.md](../../docs/NASH.md)).
+
+Every fork change is marked with a `// nash:` comment. Current patches:
+
+| File | Change |
+| --- | --- |
+| `brush-shell/src/productinfo.rs` | `PRODUCT_NAME` → `nash`; display string identifies the fork |
+| `brush-shell/src/args.rs` | usage/version strings rebranded |
+| `brush-core/src/expansion.rs` | corpus divergence D1: added `ExpansionPiece::LiteralText` — literal unquoted text is never field-split (bash splits only expansion results) but keeps glob characters active. Upstream candidate. |
+
+Planned (M1, per docs/NASH.md §4.2): `brush-core` `Gate` trait (verdict-shaped
+observation hooks) — the only substantial divergence from upstream.
+
+Updating: diff against the upstream tag, re-vendor, re-apply `// nash:` patches
+(grep for the marker), then re-run `shell/corpus/replay.py` and the brush compat
+suite (`cargo test -p brush-shell --test brush-compat-tests`).