Fix context construction and generic bindings with development S7

NEWS.md

@@ -1,5 +1,7 @@
 # btw (development version)
 
+* Updates for compatibility with S7 > 0.2.2.
+
 * `path_find_in_project()` now stops its upward search when it reaches the home directory (either `fs::path_home()` or `fs::path_home_r()`, which differ on Windows) and never treats files there as project files, so `~/AGENTS.md` or `~/CLAUDE.md` are no longer picked up as project context when the working directory is under `~` but outside a project. Home-level files are handled only by the user-level lookup. This also fixes `~/btw.md` instructions being included twice — once as the project file and once as the user-level config (#225).
 
 * `btw_client(path_btw = ...)` no longer duplicates instructions when `path_btw` is set explicitly to the same file as the user-level `btw.md` (#225).

R/btw.R

@@ -102,7 +102,7 @@ btw <- function(..., clipboard = TRUE) {
 
   if (identical(res, "")) {
     cli::cli_alert_warning("Nothing to include in the btw() context.")
-    return(invisible(BTW("")))
+    return(invisible(BTW(text = "")))
   }
 
   BTW(text = res, settings = env(clipboard = clipboard))

R/zzz.R

@@ -1,6 +1,10 @@
 .onLoad <- function(libname, pkgname) {
   # run_on_load()
-  S7::methods_register()
+  if ("S7_on_load" %in% getNamespaceExports("S7")) {
+    getExportedValue("S7", "S7_on_load")()
+  } else {
+    S7::methods_register()
+  }
 
   pkg_env <- rlang::fn_env(btw_tools)
   for (tool_def in as_ellmer_tools(.btw_tools, force = TRUE)) {
@@ -32,3 +36,13 @@ if (getRversion() < "4.3.0") {
 # R6 binds `self` and `super` at runtime; declare them so codetools doesn't
 # flag them as global variables in R CMD check.
 utils::globalVariables(c("private", "self", "super"))
+
+.onUnload <- function(...) {
+  if ("S7_on_unload" %in% getNamespaceExports("S7")) {
+    getExportedValue("S7", "S7_on_unload")()
+  }
+}
+
+if ("S7_on_build" %in% getNamespaceExports("S7")) {
+  getExportedValue("S7", "S7_on_build")()
+}