fix(decorations): only offer default devices the project can run on

README.md

@@ -209,8 +209,8 @@ require("flutter-tools").setup {
       -- this will show the current version of the flutter app from the pubspec.yaml file
       app_version = false,
       -- set to true to be able use the 'flutter_tools_decorations.device' in your statusline
-      -- this will show the currently running device if an application was started with a specific
-      -- device
+      -- this will show the running device, or, while nothing is running in a Flutter project,
+      -- the device `flutter run` would pick by default
       device = false,
       -- set to true to be able use the 'flutter_tools_decorations.project_config' in your statusline
       -- this will show the currently selected project configuration
@@ -413,7 +413,7 @@ dictionary that is created if you have set any of the decorations to `true` in y
 The currently supported decorations are:
 
 - App version - The current version of the app from the `pubspec.yaml`.
-- Device - the running device, or, while nothing is running, the device `flutter run` would default to
+- Device - the running device, or, while nothing is running in a Flutter project, the device `flutter run` would pick by default (nothing when it would prompt for one)
 - Project config - the name of the currently selected project configuration
 
 To add them to your config you can do something like

lua/flutter-tools/commands.lua

@@ -659,6 +659,7 @@ if __TEST then
   M.__run = run
   M.__get_run_args = get_run_args
   M.__update_device_from_output = update_device_from_output
+  M.__set_current_device = set_current_device
 end
 
 return M

lua/flutter-tools/decorations.lua

@@ -34,7 +34,9 @@ end
 local function device_show()
   local device = commands.current_device()
   if device then return set_decoration_item("device", device) end
-  devices.get_default_device(function(default_device)
+  local project_root = vim.fs.root(0, "pubspec.yaml")
+  if not project_root then return set_decoration_item("device", nil) end
+  devices.get_default_device(project_root, function(default_device)
     if commands.current_device() then return end
     set_decoration_item("device", default_device)
   end)

lua/flutter-tools/devices.lua

@@ -16,15 +16,13 @@ local M = {
 local EMULATOR = 1
 local DEVICE = 2
 
-local NON_EPHEMERAL_PLATFORMS = {
-  ["darwin"] = true,
-  ["darwin-arm64"] = true,
-  ["darwin-x64"] = true,
-  ["linux-arm64"] = true,
-  ["linux-x64"] = true,
-  ["windows-arm64"] = true,
-  ["windows-x64"] = true,
-  ["web-javascript"] = true,
+local PLATFORM_DIRECTORIES = {
+  { prefix = "android", directory = "android", ephemeral = true },
+  { prefix = "ios", directory = "ios", ephemeral = true },
+  { prefix = "darwin", directory = "macos", ephemeral = false },
+  { prefix = "linux", directory = "linux", ephemeral = false },
+  { prefix = "windows", directory = "windows", ephemeral = false },
+  { prefix = "web", directory = "web", ephemeral = false },
 }
 
 ---@param result string[]
@@ -109,34 +107,67 @@ local function to_device(entry)
   }
 end
 
+---@param target_platform string?
+local function platform_info(target_platform)
+  if not target_platform then return end
+  for _, info in ipairs(PLATFORM_DIRECTORIES) do
+    if vim.startswith(target_platform, info.prefix) then return info end
+  end
+end
+
+---@param entry table
+---@param project_root string?
+local function is_supported(entry, project_root)
+  if entry.isSupported == false then return false end
+  local info = platform_info(entry.targetPlatform)
+  if not project_root or not info then return true end
+  return vim.uv.fs_stat(vim.fs.joinpath(project_root, info.directory)) ~= nil
+end
+
 ---Pick the device `flutter run` would use without an explicit `-d` argument.
 ---Mirrors flutter's own resolution: a single supported device wins, otherwise
 ---a single ephemeral (non desktop/web) device wins, otherwise flutter prompts.
+---A device only counts as supported if the project has its platform directory.
 ---@param result string[]
+---@param project_root string?
 ---@return Device?
-function M.resolve_default_device(result)
-  local ok, decoded = pcall(vim.json.decode, table.concat(result, "\n"))
+function M.resolve_default_device(result, project_root)
+  -- flutter can print notices such as the startup lock message before the JSON
+  local json_start
+  for index, line in ipairs(result) do
+    if vim.startswith(line, "[") then
+      json_start = index
+      break
+    end
+  end
+  if not json_start then return end
+  local json = table.concat(vim.list_slice(result, json_start), "\n")
+  local ok, decoded = pcall(vim.json.decode, json)
   if not ok or type(decoded) ~= "table" then return end
 
-  local supported = vim.tbl_filter(function(entry) return entry.isSupported ~= false end, decoded)
+  local supported = vim.tbl_filter(
+    function(entry) return is_supported(entry, project_root) end,
+    decoded
+  )
   if #supported == 0 then return end
   if #supported == 1 then return to_device(supported[1]) end
 
-  local ephemeral = vim.tbl_filter(
-    function(entry) return not NON_EPHEMERAL_PLATFORMS[entry.targetPlatform] end,
-    supported
-  )
+  local ephemeral = vim.tbl_filter(function(entry)
+    local info = platform_info(entry.targetPlatform)
+    return not info or info.ephemeral
+  end, supported)
   if #ephemeral == 1 then return to_device(ephemeral[1]) end
 end
 
 ---Asynchronously get the device `flutter run` would default to
+---@param project_root string
 ---@param callback fun(device: Device?)
-function M.get_default_device(callback)
+function M.get_default_device(project_root, callback)
   executable.flutter(function(cmd)
     local job = Job:new({ command = cmd, args = { "devices", "--machine" } })
     job:after(vim.schedule_wrap(function(j, code)
       if code ~= 0 then return callback(nil) end
-      callback(M.resolve_default_device(j:result()))
+      callback(M.resolve_default_device(j:result(), project_root))
     end))
     job:start()
   end)

tests/commands_spec.lua

@@ -96,9 +96,11 @@ describe("commands", function()
   end)
 
   it("should keep the device id when the name is parsed from the run output", function()
+    commands.__set_current_device({ id = "macos" })
     commands.__update_device_from_output("Launching lib/main.dart on macOS in debug mode...")
 
     local device = commands.current_device()
+    assert.equal("macos", device.id)
     assert.equal("macOS", device.name)
   end)
 

tests/devices_spec.lua

@@ -100,6 +100,45 @@ INFO    | Storing crashdata in: /tmp/android-ts/emu-crash-34.2.14.db, detection
       assert.is_nil(device)
     end)
 
+    it("should treat every desktop architecture as non-ephemeral", function()
+      local device = devices.resolve_default_device(machine_output({
+        {
+          name = "Pixel 8",
+          id = "emulator-5554",
+          isSupported = true,
+          targetPlatform = "android-arm64",
+        },
+        { name = "Linux", id = "linux", isSupported = true, targetPlatform = "linux-riscv64" },
+      }))
+
+      assert.equal("emulator-5554", device.id)
+    end)
+
+    it("should skip devices whose platform directory is missing from the project", function()
+      local project_root = vim.fn.tempname()
+      vim.fn.mkdir(vim.fs.joinpath(project_root, "macos"), "p")
+
+      local device = devices.resolve_default_device(
+        machine_output({
+          { name = "iPhone 16", id = "sim-id", isSupported = true, targetPlatform = "ios" },
+          { name = "macOS", id = "macos", isSupported = true, targetPlatform = "darwin" },
+        }),
+        project_root
+      )
+      vim.fn.delete(project_root, "rf")
+
+      assert.equal("macos", device.id)
+    end)
+
+    it("should skip notices printed before the JSON output", function()
+      local output = machine_output({
+        { name = "macOS", id = "macos", isSupported = true, targetPlatform = "darwin" },
+      })
+      table.insert(output, 1, "Waiting for another flutter command to release the startup lock...")
+
+      assert.equal("macos", devices.resolve_default_device(output).id)
+    end)
+
     it("should return nil for no devices or invalid output", function()
       assert.is_nil(devices.resolve_default_device(machine_output({})))
       assert.is_nil(devices.resolve_default_device({ "not json" }))