docs: replace the retired claude-sonnet-4 in btw examples and the client error message

NEWS.md

@@ -1,5 +1,7 @@
 # btw (development version)
 
+* The documentation and the `btw_client()` error message now use `claude-sonnet-5-5` in their examples, instead of `claude-sonnet-4` and `claude-sonnet-4-20250514`, which Anthropic has retired.
+
 * `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_client.R

@@ -56,7 +56,7 @@
 #' **Array format** (unnamed list):
 #' ```yaml
 #' client:
-#'   - anthropic/claude-sonnet-4
+#'   - anthropic/claude-sonnet-5-5
 #'   - openai/gpt-4.1
 #'   - aws_bedrock/us.anthropic.claude-sonnet-4-20250514-v1:0
 #' ```
@@ -302,8 +302,8 @@ as_ellmer_client <- function(client) {
 
   cli::cli_abort(c(
     "{.arg client} must be an {.help ellmer::Chat} client, a {.val provider/model} string, or a list with {.field provider} (and optionally {.field model}).",
-    "i" = "Examples: {.or {.val {c('openai/gpt-4.1-mini', 'anthropic/claude-sonnet-4-20250514')}}}.",
-    "i" = "Or as a list: {.code list(provider = 'anthropic', model = 'claude-sonnet-4-20250514')}"
+    "i" = "Examples: {.or {.val {c('openai/gpt-4.1-mini', 'anthropic/claude-sonnet-5-5')}}}.",
+    "i" = "Or as a list: {.code list(provider = 'anthropic', model = 'claude-sonnet-5-5')}"
   ))
 }
 

R/btw_task.R

@@ -14,7 +14,7 @@
 #' ---
 #' client:
 #'   provider: anthropic
-#'   model: claude-sonnet-4
+#'   model: claude-sonnet-5-5
 #' tools: [docs, files]
 #' ---
 #'

R/tool-agent-custom.R

@@ -27,7 +27,7 @@ NULL
 #' * `title`: User-facing title for the tool. Defaults to title-cased name.
 #' * `icon`: Icon specification for the agent (see **Icon Specification**
 #'   below). Defaults to the standard agent icon.
-#' * `client`: Model specification like `"anthropic/claude-sonnet-4-20250514"`.
+#' * `client`: Model specification like `"anthropic/claude-sonnet-5-5"`.
 #'   Falls back to `btw.subagent.client` or `btw.client` options.
 #' * `tools`: List of tool names or groups available to this agent. Defaults to
 #'   all non-agent tools.
@@ -113,7 +113,7 @@ NULL
 #' @param path Path to an agent markdown file.
 #' @param client Optional. A client specification to override the agent's
 #'   configured client. Can be a string like
-#'   `"anthropic/claude-sonnet-4-20250514"`, an [ellmer::Chat] object, or a list
+#'   `"anthropic/claude-sonnet-5-5"`, an [ellmer::Chat] object, or a list
 #'   with `provider` and `model` keys. If `NULL` (default), uses the `client`
 #'   field from the agent file or falls back to btw's default client resolution.
 #'

R/tool-agent-subagent.R

@@ -82,7 +82,7 @@ BtwSubagentResult <- S7::new_class(
 #' # Configure the client and default tools for subagents
 #' withr::with_options(
 #'   list(
-#'     btw.subagent.client = "anthropic/claude-sonnet-4-20250514",
+#'     btw.subagent.client = "anthropic/claude-sonnet-5-5",
 #'     btw.subagent.tools_default = "files"
 #'   ),
 #'   {