Add shell completion for bash, zsh, and fish

Introduces a `ggt completion` command that emits accurate completion
scripts covering commands, subcommands, flags, and dynamic value
providers (app names, environments, log levels, editors). A hidden
`--__complete` root flag routes live completion requests through a
handler/provider layer. Generators suppress filename fallback in all
three shells.

Refactors the args layer in preparation: long flag names become
canonical with short forms as aliases, completion functions are inlined
into flag definitions, and MergeConflictPreferenceValues is exported for
direct reference. AppIdentityArgs is moved to app-identity.ts and
SyncJsonArgs is inlined into sync-json.ts to break ESM init cycles that
caused flag stripping in CI.

Test coverage includes shell syntax validation against real binaries,
behavioral regression tests, and snapshot tests for all three
generators. Deterministic shell versions are pinned in the nix dev shell
so CI runs against stable binaries.

Author: scott-rc

.changeset/add-shell-completion.md

@@ -0,0 +1,8 @@
+---
+"ggt": minor
+---
+
+Add `ggt completion` command for generating shell completion scripts
+
+Supports Bash, Zsh, and Fish shells. Run `ggt completion <shell>` to generate
+a completion script, then source it in your shell configuration.

.claude/rules/services.md

@@ -55,7 +55,7 @@ Defined in `src/services/output/`.
 
 ### Formatting
 
-- `sprint` / `sprintln` — template literal tag combining `chalk-template` + `dedent`. Also accepts options form: `sprint({ content, indent, boxen, ensureNewLine, ensureEmptyLineAbove })`
+- `sprint` / `sprintln` — template literal tag combining `chalk-template` + `dedent`. Also accepts options form: `sprint({ content, indent, boxen, ensureNewLine, ensureEmptyLineAbove })`. Multiline interpolated values are automatically aligned to the insertion column (`alignMultilineValues`), so use plain `"\n"` in `.join()` — never pad with manual spaces.
 - `println` / `print` — write formatted text to stdout (no-op in JSON mode unless `json` option is set)
 
 ### Interactive elements

.cspell/project-words.txt

@@ -2,6 +2,12 @@ appvalue
 clickhouse
 codegen
 commandsstop
+compadd
+compdef
+compgen
+compinit
+compreply
+cword
 dedenting
 dggt
 direnv
@@ -14,6 +20,7 @@ enotdir
 enotempty
 envrc
 eproto
+esac
 esbuild
 execa
 filesync

nix/flake.nix

@@ -13,14 +13,17 @@
       in
       {
         packages = {
+          bash = pkgs.bash;
           corepack = pkgs.corepack;
           direnv = pkgs.direnv;
+          fish = pkgs.fish;
           git = pkgs.git;
           mkcert = pkgs.mkcert;
           nix-direnv = pkgs.nix-direnv;
           nixpkgs-fmt = pkgs.nixpkgs-fmt;
           nodejs = pkgs.nodejs_20;
           yarn = pkgs.yarn.override { nodejs = flake.packages.nodejs; };
+          zsh = pkgs.zsh;
 
           ggt = pkgs.writeShellScriptBin "ggt" ''
             GGT_ENV=production "$WORKSPACE_ROOT"/dist/main.js "$@"

package.json

@@ -64,6 +64,7 @@
     "@types/tcp-port-used": "^1.0.0",
     "@types/which": "^3.0.4",
     "@types/ws": "^8.18.1",
+    "@vitest/coverage-v8": "^4.0.18",
     "ansi-escapes": "^7.2.0",
     "arg": "^5.0.2",
     "boxen": "^8.0.1",

pnpm-lock.yaml

@@ -52,7 +52,7 @@ export type FileSyncScenarioOptions = {
   /**
    * The arguments to pass to the {@linkcode SyncJson} instance.
    *
-   * @default { _: [testDirPath("local")], ["--app"]: testEnvironment.application.slug, ["--env"]: testEnvironment.name }
+   * @default { _: [testDirPath("local")], ["--application"]: testEnvironment.application.slug, ["--environment"]: testEnvironment.name }
    */
   args?: SyncJsonArgsResult;