Make all SDKs consistent in support for COPILOT_CLI_PATH

Author: SteveSandersonMS

dotnet/README.md

@@ -67,7 +67,7 @@ new CopilotClient(CopilotClientOptions? options = null)
 
 **Options:**
 
-- `CliPath` - Path to CLI executable (default: "copilot" from PATH)
+- `CliPath` - Path to CLI executable (default: `COPILOT_CLI_PATH` env var, or bundled CLI)
 - `CliArgs` - Extra arguments prepended before SDK-managed flags
 - `CliUrl` - URL of existing CLI server to connect to (e.g., `"localhost:8080"`). When provided, the client will not spawn a CLI process.
 - `Port` - Server port (default: 0 for random)

dotnet/src/Client.cs

@@ -1064,8 +1064,12 @@ private async Task VerifyProtocolVersionAsync(Connection connection, Cancellatio
 
     private static async Task<(Process Process, int? DetectedLocalhostTcpPort, StringBuilder StderrBuffer)> StartCliServerAsync(CopilotClientOptions options, ILogger logger, CancellationToken cancellationToken)
     {
-        // Use explicit path or bundled CLI - no PATH fallback
-        var cliPath = options.CliPath ?? GetBundledCliPath(out var searchedPath)
+        // Use explicit path, COPILOT_CLI_PATH env var (from options.Environment or process env), or bundled CLI - no PATH fallback
+        var envCliPath = options.Environment is not null && options.Environment.TryGetValue("COPILOT_CLI_PATH", out var envValue) ? envValue
+            : System.Environment.GetEnvironmentVariable("COPILOT_CLI_PATH");
+        var cliPath = options.CliPath
+            ?? envCliPath
+            ?? GetBundledCliPath(out var searchedPath)
             ?? throw new InvalidOperationException($"Copilot CLI not found at '{searchedPath}'. Ensure the SDK NuGet package was restored correctly or provide an explicit CliPath.");
         var args = new List<string>();
 

go/client.go

@@ -199,15 +199,29 @@ func NewClient(options *ClientOptions) *Client {
 		opts.Env = os.Environ()
 	}
 
-	// Check environment variable for CLI path
-	if cliPath := os.Getenv("COPILOT_CLI_PATH"); cliPath != "" {
-		opts.CLIPath = cliPath
+	// Check effective environment for CLI path (only if not explicitly set via options)
+	if opts.CLIPath == "" {
+		if cliPath := getEnvValue(opts.Env, "COPILOT_CLI_PATH"); cliPath != "" {
+			opts.CLIPath = cliPath
+		}
 	}
 
 	client.options = opts
 	return client
 }
 
+// getEnvValue looks up a key in an environment slice ([]string of "KEY=VALUE").
+// Returns the value if found, or empty string otherwise.
+func getEnvValue(env []string, key string) string {
+	prefix := key + "="
+	for i := len(env) - 1; i >= 0; i-- {
+		if strings.HasPrefix(env[i], prefix) {
+			return env[i][len(prefix):]
+		}
+	}
+	return ""
+}
+
 // parseCliUrl parses a CLI URL into host and port components.
 //
 // Supports formats: "host:port", "http://host:port", "https://host:port", or just "port".

python/README.md

@@ -125,7 +125,7 @@ CopilotClient(
 
 **SubprocessConfig** — spawn a local CLI process:
 
-- `cli_path` (str | None): Path to CLI executable (default: bundled binary)
+- `cli_path` (str | None): Path to CLI executable (default: `COPILOT_CLI_PATH` env var, or bundled binary)
 - `cli_args` (list[str]): Extra arguments for the CLI executable
 - `cwd` (str | None): Working directory for CLI process (default: current dir)
 - `use_stdio` (bool): Use stdio transport instead of TCP (default: True)

python/copilot/client.py

@@ -794,16 +794,21 @@ def __init__(
         else:
             self._actual_port = None
 
-            # Resolve CLI path: explicit > bundled binary
+            # Resolve CLI path: explicit > COPILOT_CLI_PATH env var > bundled binary
+            effective_env = config.env if config.env is not None else os.environ
             if config.cli_path is None:
-                bundled_path = _get_bundled_cli_path()
-                if bundled_path:
-                    config.cli_path = bundled_path
+                env_cli_path = effective_env.get("COPILOT_CLI_PATH")
+                if env_cli_path:
+                    config.cli_path = env_cli_path
                 else:
-                    raise RuntimeError(
-                        "Copilot CLI not found. The bundled CLI binary is not available. "
-                        "Ensure you installed a platform-specific wheel, or provide cli_path."
-                    )
+                    bundled_path = _get_bundled_cli_path()
+                    if bundled_path:
+                        config.cli_path = bundled_path
+                    else:
+                        raise RuntimeError(
+                            "Copilot CLI not found. The bundled CLI binary is not available. "
+                            "Ensure you installed a platform-specific wheel, or provide cli_path."
+                        )
 
             # Resolve use_logged_in_user default
             if config.use_logged_in_user is None: