fix: support fish completion script

packages/opencode/src/cli/completion.ts

@@ -0,0 +1,103 @@
+import { basename } from "path"
+
+const completionShTemplate = `###-begin-{{app_name}}-completions-###
+#
+# yargs command completion script
+#
+# Installation: {{app_path}} {{completion_command}} >> ~/.bashrc
+#    or {{app_path}} {{completion_command}} >> ~/.bash_profile on OSX.
+#
+_{{app_name}}_yargs_completions()
+{
+    local cur_word args type_list
+
+    cur_word="\${COMP_WORDS[COMP_CWORD]}"
+    args=("\${COMP_WORDS[@]}")
+
+    # ask yargs to generate completions.
+    # see https://stackoverflow.com/a/40944195/7080036 for the spaces-handling awk
+    mapfile -t type_list < <({{app_path}} --get-yargs-completions "\${args[@]}")
+    mapfile -t COMPREPLY < <(compgen -W "$( printf '%q ' "\${type_list[@]}" )" -- "\${cur_word}" |
+        awk '/ / { print "\\""$0"\\"" } /^[^ ]+$/ { print $0 }')
+
+    # if no match was found, fall back to filename completion
+    if [ \${#COMPREPLY[@]} -eq 0 ]; then
+      COMPREPLY=()
+    fi
+
+    return 0
+}
+complete -o bashdefault -o default -F _{{app_name}}_yargs_completions {{app_name}}
+###-end-{{app_name}}-completions-###
+`
+
+const completionZshTemplate = `#compdef {{app_name}}
+###-begin-{{app_name}}-completions-###
+#
+# yargs command completion script
+#
+# Installation: {{app_path}} {{completion_command}} >> ~/.zshrc
+#    or {{app_path}} {{completion_command}} >> ~/.zprofile on OSX.
+#
+_{{app_name}}_yargs_completions()
+{
+  local reply
+  local si=$IFS
+  IFS=$'\n' reply=($(COMP_CWORD="$((CURRENT-1))" COMP_LINE="$BUFFER" COMP_POINT="$CURSOR" {{app_path}} --get-yargs-completions "\${words[@]}"))
+  IFS=$si
+  if [[ \${#reply} -gt 0 ]]; then
+    _describe 'values' reply
+  else
+    _default
+  fi
+}
+if [[ "'\${zsh_eval_context[-1]}" == "loadautofunc" ]]; then
+  _{{app_name}}_yargs_completions "$@"
+else
+  compdef _{{app_name}}_yargs_completions {{app_name}}
+fi
+###-end-{{app_name}}-completions-###
+`
+
+const completionFishTemplate = `###-begin-{{app_name}}-completions-###
+#
+# yargs command completion script
+#
+# Installation: {{app_path}} {{completion_command}} > ~/.config/fish/completions/{{app_name}}.fish
+#
+complete -f -c {{app_name}} -a '({{app_path}} --get-yargs-completions (commandline -o)[2..-1])'
+###-end-{{app_name}}-completions-###
+`
+
+const SHELLS = ["bash", "zsh", "fish"] as const
+
+export type CompletionShell = (typeof SHELLS)[number]
+
+export function isCompletionShell(s: string | undefined): s is CompletionShell {
+  return !!s && (SHELLS as readonly string[]).includes(s)
+}
+
+// yargs 18 only ships bash/zsh templates and picks them from $SHELL, ignoring the
+// shell positional arg. Generate the script ourselves so `completion fish` (and
+// `completion zsh` under a bash $SHELL) emit the right template.
+export function generateCompletionScript(
+  shell: CompletionShell,
+  appPath: string,
+  appName: string,
+): string {
+  const template =
+    shell === "fish"
+      ? completionFishTemplate
+      : shell === "zsh"
+        ? completionZshTemplate
+        : completionShTemplate
+  return template
+    .replace(/{{app_name}}/g, appName)
+    .replace(/{{completion_command}}/g, "completion")
+    .replace(/{{app_path}}/g, appPath)
+}
+
+export function generateCompletionScriptForArgs(shell: CompletionShell): string {
+  const appPath = process.argv[1]
+  return generateCompletionScript(shell, appPath, basename(appPath))
+}

packages/opencode/src/index.ts

@@ -29,9 +29,19 @@ import { DbCommand } from "./cli/cmd/db"
 import { errorMessage } from "./util/error"
 import { PluginCommand } from "./cli/cmd/plug"
 import { Heap } from "./cli/heap"
+import { generateCompletionScriptForArgs, isCompletionShell } from "./cli/completion"
 
 const args = hideBin(process.argv)
 
+// yargs' built-in completion only knows bash/zsh and picks the template from
+// $SHELL, ignoring the shell positional argument. Handle an explicit shell
+// ourselves so `completion fish` (and `completion zsh` under a bash $SHELL)
+// emit the right script.
+if (args[0] === "completion" && isCompletionShell(args[1])) {
+  process.stdout.write(generateCompletionScriptForArgs(args[1]) + EOL)
+  process.exit(0)
+}
+
 function show(out: string) {
   const text = out.trimStart()
   if (!text.startsWith("opencode ")) {

packages/opencode/test/cli/completion.test.ts

@@ -0,0 +1,36 @@
+import { describe, expect, test } from "bun:test"
+import {
+  generateCompletionScript,
+  isCompletionShell,
+} from "../../src/cli/completion"
+
+describe("cli.completion", () => {
+  test("generates a fish script for `completion fish`", () => {
+    const script = generateCompletionScript("fish", "opencode", "opencode")
+    expect(script).toContain(
+      "complete -f -c opencode -a '(opencode --get-yargs-completions (commandline -o)[2..-1])'",
+    )
+    expect(script).not.toContain("COMP_WORDS")
+  })
+
+  test("generates a zsh script for `completion zsh`", () => {
+    const script = generateCompletionScript("zsh", "opencode", "opencode")
+    expect(script).toContain("#compdef opencode")
+    expect(script).not.toContain("COMP_WORDS")
+  })
+
+  test("generates a bash script for `completion bash`", () => {
+    const script = generateCompletionScript("bash", "opencode", "opencode")
+    expect(script).toContain(
+      "complete -o bashdefault -o default -F _opencode_yargs_completions opencode",
+    )
+  })
+
+  test("recognizes only known shells", () => {
+    expect(isCompletionShell("bash")).toBe(true)
+    expect(isCompletionShell("zsh")).toBe(true)
+    expect(isCompletionShell("fish")).toBe(true)
+    expect(isCompletionShell("powershell")).toBe(false)
+    expect(isCompletionShell(undefined)).toBe(false)
+  })
+})