Add initial shell completion support

Update the `tell` command to not complete with files unless the `-f`
flag is set.

app/cli/cmd/completion.go

@@ -0,0 +1,75 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+var completionLongDesc = fmt.Sprintf(`To load completions:
+Bash:
+
+  $ source <(%[1]s completion bash)
+
+  # To load completions for each session, execute once:
+  # Linux:
+  $ %[1]s completion bash > /etc/bash_completion.d/%[1]s
+  # macOS:
+  $ %[1]s completion bash > $(brew --prefix)/etc/bash_completion.d/%[1]s
+
+Zsh:
+
+  # If shell completion is not already enabled in your environment,
+  # you will need to enable it.  You can execute the following once:
+
+  $ echo "autoload -U compinit; compinit" >> ~/.zshrc
+
+  # To load completions for each session, execute once:
+  $ %[1]s completion zsh > "${fpath[1]}/_%[1]s"
+
+  # You will need to start a new shell for this setup to take effect.
+
+fish:
+
+  $ %[1]s completion fish | source
+
+  # To load completions for each session, execute once:
+  $ %[1]s completion fish > ~/.config/fish/completions/%[1]s.fish
+
+PowerShell:
+
+  PS> %[1]s completion powershell | Out-String | Invoke-Expression
+
+  # To load completions for every new session, run:
+  PS> %[1]s completion powershell > %[1]s.ps1
+  # and source this file from your PowerShell profile.
+`, RootCmd.Name())
+
+var completionCmd = &cobra.Command{
+	Use:   "completion [bash|zsh|fish|powershell]",
+	Short: "Generate completion script",
+	Long:  completionLongDesc,
+
+	DisableFlagsInUseLine: true,
+	ValidArgs:             []string{"bash", "zsh", "fish", "powershell"},
+	Args:                  cobra.MatchAll(cobra.ExactArgs(1), cobra.OnlyValidArgs),
+	Run:                   completion,
+}
+
+func init() {
+	RootCmd.AddCommand(completionCmd)
+}
+
+func completion(cmd *cobra.Command, args []string) {
+	switch args[0] {
+	case "bash":
+		cmd.Root().GenBashCompletion(os.Stdout)
+	case "zsh":
+		cmd.Root().GenZshCompletion(os.Stdout)
+	case "fish":
+		cmd.Root().GenFishCompletion(os.Stdout, true)
+	case "powershell":
+		cmd.Root().GenPowerShellCompletionWithDesc(os.Stdout)
+	}
+}

app/cli/cmd/tell.go

@@ -30,7 +30,10 @@ var tellCmd = &cobra.Command{
 	Short:   "Send a prompt for the current plan",
 	// Long:  ``,
 	Args: cobra.RangeArgs(0, 1),
-	Run:  doTell,
+	ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return []string{}, cobra.ShellCompDirectiveNoFileComp
+	},
+	Run: doTell,
 }
 
 func init() {