gadenbuie · Sep 7, 2026 · Sep 7, 2026 · Sep 7, 2026 · Sep 7, 2026 · Sep 7, 2026
diff --git a/DESCRIPTION b/DESCRIPTION
@@ -35,7 +35,7 @@ Imports:
     cli,
     clipr,
     dplyr,
-    ellmer (>= 0.3.0),
+    ellmer (>= 0.4.2),
     frontmatter,
     fs,
     jsonlite,

diff --git a/NEWS.md b/NEWS.md
@@ -4,6 +4,14 @@
 
 * `btw docs` and `btw pkg src` commands now auto-load an in-development package found in the current directory (or its `pkg-r/`, `R/` subfolder) with `pkgload::load_all()` before running, so results reflect uncommitted local changes. Pass `--no-dev` to disable this and use the installed package instead (#212).
 
+## Bug fixes
+
+* `btw --version` now works without a subcommand. Previously, Rapp's required top-level switch caused the CLI to print usage and exit before the version flag was ever checked.
+
+## Other changes
+
+* btw now requires ellmer (>= 0.4.2). The `set_model()` compatibility shim was removed, and `client_get_models()` now delegates to ellmer's `models_list()` generic, replacing a bespoke per-provider dispatch table (#214).
+
 # btw 1.4.0
 
 ## New features

diff --git a/R/utils-ellmer.R b/R/utils-ellmer.R
@@ -1,78 +1,16 @@
 client_get_models <- function(client) {
-  provider <- client$get_provider()
+  models_list <- asNamespace("ellmer")[["models_list"]]
 
-  models_fns <- list(
-    ProviderAnthropic = function(p) {
-      ellmer::models_anthropic(
-        base_url = p@base_url,
-        credentials = p@credentials
-      )
-    },
-    ProviderGoogleGemini = function(p) {
-      ellmer::models_google_gemini(
-        base_url = p@base_url,
-        credentials = p@credentials
-      )
-    },
-    ProviderAWSBedrock = function(p) {
-      base_url <- sub("bedrock-runtime", "bedrock", p@base_url)
-      ellmer::models_aws_bedrock(profile = p@profile, base_url = base_url)
-    },
-    ProviderOpenAI = function(p) {
-      ellmer::models_openai(base_url = p@base_url, credentials = p@credentials)
-    },
-    ProviderMistral = function(p) {
-      ellmer::models_mistral()
-    },
-    ProviderLMStudio = function(p) {
-      base_url <- sub("/v1$", "", p@base_url)
-      ellmer::models_lmstudio(base_url = base_url, credentials = p@credentials)
-    },
-    ProviderVllm = function(p) {
-      ellmer::models_vllm(base_url = p@base_url, credentials = p@credentials)
-    },
-    ProviderOllama = function(p) {
-      base_url <- sub("/v1$", "", p@base_url)
-      ellmer::models_ollama(base_url = base_url, credentials = p@credentials)
-    },
-    ProviderPortkeyAI = function(p) {
-      ellmer::models_portkey(base_url = p@base_url)
-    },
-    ProviderOpenAICompatible = function(p) {
-      base_url <- sub("/v1$", "", p@base_url)
-      ellmer::models_openai(base_url = p@base_url, credentials = p@credentials)
-    }
-  )
-
-  try_get_models <- function(fn, provider) {
-    tryCatch(fn(provider), error = function(e) {
+  tryCatch(
+    models_list(client),
+    error = function(e) {
       cli::cli_warn(
-        "Failed to fetch models for provider {provider@name}",
+        "Failed to fetch models for provider {client$get_provider()@name}",
         parent = e
       )
       NULL
-    })
-  }
-
-  if (provider@name == "LM Studio") {
-    return(try_get_models(models_fns$ProviderLMStudio, provider))
-  }
-
-  for (cls in names(models_fns)) {
-    if (inherits(provider, sprintf("ellmer::%s", cls))) {
-      return(
-        tryCatch(models_fns[[cls]](provider), error = function(e) {
-          cli::cli_warn(
-            "Failed to fetch models for provider {provider@name}",
-            parent = e
-          )
-          NULL
-        })
-      )
     }
-  }
-
-  NULL
+  )
 }
 
 btw_client_config_name <- function(cfg) {
@@ -88,7 +26,9 @@ btw_client_config_name <- function(cfg) {
   if (inherits(cfg, "Chat")) {
     provider <- tryCatch(cfg$get_provider()@name, error = function(e) NULL)
     model <- tryCatch(cfg$get_model(), error = function(e) NULL)
-    if (!is.null(provider) && !is.null(model)) return(paste0(provider, "/", model))
+    if (!is.null(provider) && !is.null(model)) {
+      return(paste0(provider, "/", model))
+    }
     return(model %||% provider %||% "unknown")
   }
   "unknown"
@@ -234,30 +174,19 @@ chat_get_tokens <- function(client) {
   cached_tokens <- 0
 
   if (!is.null(tokens) && nrow(tokens) > 0) {
-    if (utils::packageVersion("ellmer") <= "0.3.0") {
-      last_user <- tokens[tokens$role == "user", ]
-      if (nrow(last_user) > 0) {
-        input_tokens <- as.integer(utils::tail(last_user$tokens_total, 1))
-      }
-      tokens_assistant <- tokens[tokens$role == "assistant", ]
-      if (nrow(tokens_assistant) > 0) {
-        output_tokens <- as.integer(sum(tokens_assistant$tokens))
-      }
-    } else {
-      # output tokens are by turn, so we sum them all
-      if ("output" %in% colnames(tokens)) {
-        output_tokens <- sum(tokens$output)
-      }
-      # input and cached tokens are accumulated in the last API call
-      if ("input" %in% colnames(tokens)) {
-        input_tokens <-
-          tokens$input[[length(tokens$input)]]
-      }
-      if ("cached_input" %in% colnames(tokens)) {
-        cached_tokens <- tokens$cached_input[[
-          length(tokens$cached_input)
-        ]]
-      }
+    # output tokens are by turn, so we sum them all
+    if ("output" %in% colnames(tokens)) {
+      output_tokens <- sum(tokens$output)
+    }
+    # input and cached tokens are accumulated in the last API call
+    if ("input" %in% colnames(tokens)) {
+      input_tokens <-
+        tokens$input[[length(tokens$input)]]
+    }
+    if ("cached_input" %in% colnames(tokens)) {
+      cached_tokens <- tokens$cached_input[[
+        length(tokens$cached_input)
+      ]]
     }
   }
 

diff --git a/R/zzz.R b/R/zzz.R
@@ -7,18 +7,6 @@
     assign(tool_def@name, tool_def, envir = pkg_env)
   }
 
-  # Patch ellmer:::Chat to add set_model() if it doesn't exist
-  ellmer_chat <- utils::getFromNamespace("Chat", "ellmer")
-  if (!is.null(ellmer_chat)) {
-    if (!"set_model" %in% names(ellmer_chat$public_methods)) {
-      ellmer_chat$set("public", "set_model", function(model) {
-        old <- private$provider@model
-        private$provider@model <- model
-        invisible(old)
-      })
-    }
-  }
-
   rlang::run_on_load()
 }
 

diff --git a/exec/btw.R b/exec/btw.R
@@ -16,6 +16,7 @@ suppressPackageStartupMessages({
 # Global options --------------------------------------------------------------
 
 #| description: Print btw version and exit.
+#| negative_alias: false
 version <- FALSE
 
 if (version) {
@@ -816,6 +817,7 @@ btw_cran_info <- function(package, json = FALSE) {
 
 # Subcommand dispatch ---------------------------------------------------------
 
+#| required: false
 switch(
   group <- "",
 

diff --git a/tests/testthat/_snaps/btw_client.md b/tests/testthat/_snaps/btw_client.md
@@ -3,7 +3,7 @@
     Code
       print(chat)
     Output
-      <Chat Anthropic/claude-sonnet-4-6 turns=1 input=0 output=0 cost=$0.00>
+      <Chat Anthropic/DEFAULT_MODEL turns=1 input=0 output=0 cost=$0.00>
       -- system ----------------------------------------------------------------------
       # System and Session Context
 
@@ -35,7 +35,7 @@
     Code
       print(chat)
     Output
-      <Chat Anthropic/claude-sonnet-4-6 turns=1 input=0 output=0 cost=$0.00>
+      <Chat Anthropic/DEFAULT_MODEL turns=1 input=0 output=0 cost=$0.00>
       -- system ----------------------------------------------------------------------
       # System and Session Context
 

diff --git a/tests/testthat/helpers.R b/tests/testthat/helpers.R
@@ -47,6 +47,15 @@ expect_btw_tool_result <- function(
 }
 
 scrub_system_info <- function(x) {
+  x <- sub(
+    sprintf(
+      "Anthropic/%s",
+      ellmer::chat_anthropic(credentials = \() "not-a-real-key")$get_model()
+    ),
+    "Anthropic/DEFAULT_MODEL",
+    x,
+    fixed = TRUE
+  )
   x <- sub(R.version.string, "R VERSION", x, fixed = TRUE)
   x <- sub(sessioninfo::os_name(), "OPERATING SYSTEM", x, fixed = TRUE)
   x <- sub(version$system, "SYSTEM VERSION", x, fixed = TRUE)

diff --git a/tests/testthat/test-tool-agent-subagent.R b/tests/testthat/test-tool-agent-subagent.R
@@ -82,7 +82,7 @@ test_that("subagent_client() consults btw.md if options are unset", {
 
   agent_client <- subagent_client()
   expect_equal(agent_client$get_provider()@name, "OpenRouter")
-  expect_equal(agent_client$get_provider()@model, "super-cool-model")
+  expect_equal(agent_client$get_model(), "super-cool-model")
 
   expect_equal(
     names(agent_client$get_tools()),

diff --git a/tests/testthat/test-tool-pkg-src.R b/tests/testthat/test-tool-pkg-src.R
@@ -1,3 +1,6 @@
+duckdb_extensions <- withr::local_tempdir()
+local_options(duckdb.home = duckdb_extensions)
+
 # Test btw_tool_pkg_src_list_impl ----------------------------------------------
 
 test_that("btw_tool_pkg_src_list_impl returns exported objects by default", {