refactor: decompose the well-traveled code paths (exploration 0276)

.changeset/well-traveled-refactors-0276.md

@@ -0,0 +1,17 @@
+---
+'@xnetjs/core': minor
+'@xnetjs/data': patch
+'@xnetjs/plugins': patch
+'@xnetjs/react': patch
+---
+
+Add the shared Last-Write-Wins ordering module to `@xnetjs/core`
+(`compareChangeApplicationOrder`, `compareLwwStamps`, `lwwWins`,
+`lwwUpdateGuardSql`, `LwwStamp`) — the single canonical LWW comparison used
+across the stack (protocol §L1.7).
+
+`@xnetjs/data`, `@xnetjs/plugins`, and `@xnetjs/react` adopt it and receive
+internal decompositions of their most-churned modules (NodeStore query
+compiler/hydration/transaction execution, ai-surface tool registry and
+resource URI router, XNetProvider provider units). No public API changes in
+those packages.

CLAUDE.md

@@ -1,5 +1,24 @@
 # xNet — agent conventions
 
+## Barrel exports (index.ts) — sub-barrel policy (0276)
+
+The `react`/`data`/`plugins` root barrels are the highest-churn files in the
+repo (90/87/47 commits in 8 months) — every feature appending re-exports there
+creates standing merge conflicts and degrades tree-shaking.
+
+- **New surface lands in a scoped sub-barrel**, not the root barrel: add (or
+  extend) a feature-area file — e.g. `packages/react/src/hooks/index.ts`,
+  `packages/data/src/store/index.ts` — and re-export the _area_ from the root
+  with ONE grouped block, so the root barrel gains at most one line per area,
+  not five lines per feature.
+- **Never `export *` from the root barrel** — named re-exports only (keeps
+  tree-shaking and makes API-surface diffs reviewable).
+- **Internal modules don't get barrel exports at all.** If nothing outside the
+  package imports it (e.g. `packages/react/src/provider/*` units), leave it
+  out of every barrel.
+- Removing/renaming anything already exported from a root barrel is a
+  **major** bump (see Changesets below) — bump from the diff.
+
 ## Changesets (npm release intent)
 
 Every change to a **publishable** `packages/*` library MUST produce a