agent-output-optimizer

Agent-optimized output for Vite. Detects AI coding agents and replaces verbose build output with compact, structured JSON.

Inspired by PAO for PHP.

Why

When an AI agent (Claude Code, Cursor, Devin, Gemini CLI, etc.) runs vite build or vite dev, the agent's context window gets flooded with hundreds of lines of ASCII tables, ANSI color codes, chunk reports, and stack traces it has to parse anyway.

agent-output-optimizer detects these environments automatically and swaps the output for a single-line JSON that the agent can parse in one step — freeing tokens and improving fix accuracy.

When a human runs the same command, the output is completely unchanged.

Install

npm install -D agent-output-optimizer
# or
pnpm add -D agent-output-optimizer

Requires Vite 5, 6, 7, or 8.

Usage

// vite.config.ts
import { defineConfig } from 'vite';
import optimizer from 'agent-output-optimizer';

export default defineConfig({
  plugins: [
    optimizer(),
    // ...your other plugins
  ],
});

That's it. No config needed. The plugin activates only when an AI agent is detected.

What you get

Build — successful

{"mode":"build","result":"passed","duration_ms":2120}

Build — failed

{
  "mode": "build",
  "result": "failed",
  "duration_ms": 1972,
  "errors": [
    {
      "message": "Could not load ../../../resources/js/routess",
      "code": "UNLOADABLE_DEPENDENCY",
      "file": "resources/js/pages/dashboard.tsx",
      "line": 4,
      "column": 27
    }
  ]
}

Dev server

{"mode":"dev","ready":true,"url":"http://localhost:5173","port":5173,"duration_ms":6}

HMR (opt-in)

{"mode":"hmr","file":"resources/js/pages/dashboard.tsx","modules":1}

Options

optimizer({
  force: false,    // force-enable even if no agent detected
  disable: false,  // force-disable even if agent detected
  chunks: false,   // include per-chunk size/gzip info in build output
  gzip: true,      // compute gzip sizes when chunks is true
  hmr: false,      // emit a JSON line per HMR update
});

chunks: true — bundle-size auditing

{
  "mode": "build",
  "result": "passed",
  "duration_ms": 2254,
  "chunks": [
    { "file": "assets/app-BatQDfhm.js", "size": 230317, "gzip": 65235 },
    { "file": "assets/app-BwJKfC5G.css", "size": 91182, "gzip": 15164 }
  ]
}

Detected agents

Auto-detects via environment variables and filesystem markers:

| Agent | Detection | |---|---| | Claude Code | CLAUDECODE, CLAUDE_CODE | | Cursor | CURSOR_AGENT, CURSOR_TRACE_ID, CURSOR_EXTENSION_HOST_ROLE | | Gemini CLI | GEMINI_CLI | | Codex CLI | CODEX_SANDBOX, CODEX_CI, CODEX_THREAD_ID | | GitHub Copilot | COPILOT_CLI, COPILOT_MODEL, COPILOT_ALLOW_ALL, COPILOT_GITHUB_TOKEN | | Antigravity | ANTIGRAVITY_AGENT | | Augment CLI | AUGMENT_AGENT | | OpenCode | OPENCODE_CLIENT, OPENCODE | | Amp | AMP_CURRENT_THREAD_ID | | Pi | PI_CODING_AGENT | | Kiro CLI | KIRO_AGENT_PATH | | Replit | REPL_ID | | Devin | /opt/.devin file | | Generic | AI_AGENT |

What it does

• Silences Vite's default CLI output (banner, progress, chunk tables, stack traces).
• Strips ANSI escape codes and box-drawing characters from error messages.
• Extracts structured error info (file, line, column, plugin, error code) from both rollup/rolldown error objects and formatted frames.
• Intercepts process.stderr.write so Vite's CLI-level error prints don't leak after the JSON.
• Emits exactly one JSON line per build on stdout, regardless of project size.

License

MIT