Claude Code × Antigravity + Codex + Copilot + Cursor — MCP Bridge

Drive four external coding CLIs — Google's Antigravity (Gemini 3.6 Flash), OpenAI Codex, the GitHub Copilot CLI, and Cursor — as sub-agents inside Claude Code. Text answers, image generation, real repo work, and parallel swarms, on quota you already pay for.

One MCP server, four backends. It exposes Google Antigravity, OpenAI Codex, the GitHub Copilot CLI, and Cursor to Claude Code as clean MCP tools so you can delegate work to a different model family mid-task — without leaving your terminal, and on the subscriptions you already have. Each backend is independent: install one, two, three, or all four.

• 🛰️ Antigravity (agy, Gemini 3.6 Flash High). Fast, cheap tool-calling — and the only backend with an image model. Its headless print mode (agy -p) historically had a stdout bug: it wrote the answer to the controlling terminal instead of its stdout, so anything capturing stdout got nothing (and, under a TUI, agy's text leaked into the host's prompt). agy 1.0.15 fixed this on Windows — -p now writes the clean answer to stdout — so the bridge prefers stdout and falls back to reading agy's own transcript files only when stdout is empty (older agy, non-Windows, or --sandbox runs). It still detaches agy from the terminal so older versions can't leak.
• 🤖 Codex (codex exec, OpenAI). A strong reasoner for real code/repo work. It writes its final message straight to a file the bridge asks for (no scraping), supports model selection, and has a real, enforced sandbox.
• 🐙 Copilot (copilot -p, GitHub). GitHub's agentic coder. Stdout-native like Codex (-s prints just the answer), with model selection (--model), a best-effort tool/path permission knob, and a deterministic resume mechanism (the bridge sets each session's UUID itself).
• ✳️ Cursor (cursor-agent -p, Cursor). Cursor's agentic coder, with the widest model menu — GPT, Claude, Grok, and Composer via --model (validated against cursor-agent models). Stdout-native like Codex/Copilot (--output-format text prints just the answer), an agent-enforced sandbox (read-only via --mode ask), and a deterministic resume mechanism (the bridge mints each chat's id itself via create-chat). No image model.

All four share the same niceties: a *_continue to resume a thread, a live "watch" window to see the agent work, a unified agent_swarm that runs many tasks in parallel across all backends at once, and *_status diagnostics that spend no quota.

[!WARNING] This runs unsandboxed code with your privileges. agy -p auto-executes its tools (read/write files, run shell commands, reach the network) with no usable approval gate — its --sandbox blocks only shell commands, leaving file writes and network egress wide open. codex exec also runs autonomously, but its sandbox flag (default read-only) is a real, enforced boundary. copilot -p runs headless with --allow-all-tools; its sandbox maps to best-effort tool/path permissions (read-only denies the local write/shell tools) — safer than agy, but not an OS sandbox like Codex's. cursor-agent -p runs headless with --trust (and --force for writes); its sandbox is agent-enforced (read-only = --mode ask, which makes the write/shell tools unavailable) — best-effort like Copilot, not an OS sandbox. In all four cases the workspace argument is a starting context, not a security boundary. Only use these with trusted prompts on trusted content; for real isolation, run the bridge inside a container or VM. Full details →

Why you'd want this

The four backends at a glance

The bridge normalizes all four CLIs into the same shape, but they differ where it matters. Pick per task:

How it works

All four backends run headless and one-shot per call; the bridge's job is to get a clean answer out of each and hand it to Claude Code as a plain string.

flowchart LR
    A([Claude Code]) -- "MCP tool call" --> B["bridge<br/>(server.py)"]
    B -- "antigravity_*" --> C[agy -p]
    B -- "codex_*" --> D[codex exec]
    B -- "copilot_*" --> E[copilot -p]
    B -- "cursor_*" --> F[cursor-agent -p]
    C -- "json / stream-json (1.1.8+)<br/>else stdout or transcript.jsonl / .db" --> B
    D -- "output-last-message file" --> B
    E -- "stdout (-s silent)" --> B
    F -- "stdout (--output-format text)" --> B
    B -- "plain text" --> A

Antigravity. On agy 1.1.8+ the bridge asks for structured output and reads a contractual field instead of guessing: plain calls use --output-format json and return its response, while watch mode uses --output-format stream-json and rebuilds the answer from the stream's terminal result event (the same shape the Cursor bridge already used). Both also carry a conversation_id, which the bridge records so antigravity_continue pins exactly the thread it last ran in that workspace.

Older agy has no such flag, so the original path stays: on 1.0.15+ (Windows) agy -p writes its clean answer to stdout and the bridge returns that; on older agy — or non-Windows, or a --sandbox run — stdout is empty and the bridge falls back to agy's own transcript at:

~/.gemini/antigravity-cli/brain/<conv-id>/.system_generated/logs/transcript.jsonl

For that fallback it locates the conversation via cache/last_conversations.json (falling back to the newest brain/ directory touched since launch), streams the transcript, and returns the final source=MODEL, status=DONE, type=PLANNER_RESPONSE entry — the answer, minus the intermediate tool-calling steps (or the SQLite .db agy dual-writes, when no JSONL exists). This fallback still runs on 1.1.8+ whenever a run yields no result, so nothing depends on the structured path alone.

Codex. codex exec is well-behaved: the bridge passes -o/--output-last-message <file> and codex writes its final message straight there — no scraping. Continue works by capturing the session id from codex's own rollout files (~/.codex/sessions/.../rollout-*.jsonl) and resuming with codex exec resume <id>, falling back to the newest on-disk session for that cwd after a server restart.

Copilot. copilot -p "<prompt>" -s runs a prompt non-interactively and prints the clean final answer to stdout — the bridge reads it there, no scraping. It runs headless with --allow-all-tools --no-ask-user --no-auto-update (so it never blocks on a prompt), and disables copilot's flaky builtin GitHub-API MCP by default for predictable latency (COPILOT_GITHUB_MCP=1 re-enables it). Continue is deterministic: copilot's --session-id <uuid> both sets a new session's id and resumes an existing one, so the bridge generates the UUID itself, pins it to the workspace, and resumes that exact session — falling back after a restart to the newest on-disk session (~/.copilot/session-state/<id>/workspace.yaml) whose recorded cwd matches.

Cursor. cursor-agent -p --output-format text --trust "<prompt>" runs a prompt non-interactively and writes the clean final answer straight to stdout — the bridge reads it there, no scraping (--trust trusts the workspace so it never blocks on a prompt). Continue is deterministic and race-free: cursor-agent create-chat mints a fresh chat and prints its id, so the bridge mints the id itself, pins it to the workspace, and resumes that exact chat with -p --resume <chatId> — no rollout-scraping. After a restart it falls back to the newest on-disk chat under ~/.cursor/chats/<md5(workspace)>/<chat-id>/ whose meta.json cwd matches (the chat-dir hash is itself md5 of the workspace path).

Set up in 60 seconds

Prerequisites — install whichever backend(s) you want, and sign in once each:

• Antigravity: install agy and sign in to Antigravity once (via the IDE or agy -i).
• Codex: install codex and run codex login once (ChatGPT account or API key).
• Copilot: install copilot (npm i -g @github/copilot, or winget install GitHub.Copilot) and run copilot then /login once (or set a COPILOT_GITHUB_TOKEN/GH_TOKEN env var).
• Cursor: install cursor-agent (curl https://cursor.com/install -fsSL | bash) and run cursor-agent login once (or set a CURSOR_API_KEY env var).

You don't need all four — the tools for a missing CLI simply report "not found" via their *_status tool.

Recommended — no clone, you control updates

With uv installed, register the bridge straight from PyPI under mcpServers in ~/.claude.json — no path to hardcode, no git pull to remember:

"agent-intern": {
  "command": "uvx",
  "args": ["agent-intern"]
}

uvx pins to the version it first caches and does not auto-upgrade, so you never run an update you didn't choose — important, since the bridge runs unsandboxed code: a surprise (or compromised) release can't execute until you opt in. When the startup check warns that a newer release is out, upgrade deliberately and restart Claude Code:

uvx agent-intern@latest      # fetch + run the newest release (refreshes uv's cache)

[!TIP] Prefer hands-off auto-updates? Put "args": ["agent-intern@latest"] in the config instead — every launch runs the newest release. Convenient, but it pulls new code without asking each time.

From source

Clone it instead if you want to hack on the bridge or pin a local copy:

git clone https://github.com/SinanTufekci/agent-intern.git
cd agent-intern
pip install fastmcp
python test_smoke.py        # 4 real round-trips (ask, continue, image, swarm) — prints four PASS lines

[!NOTE] The smoke test costs a tiny bit of quota and takes ~30–60 s. It exercises the Antigravity path.

Then point Claude Code at the absolute path to server.py under mcpServers in ~/.claude.json:

"agent-intern": {
  "command": "python",
  "args": ["C:\\path\\to\\server.py"]
}

"agent-intern": {
  "command": "python3",
  "args": ["/path/to/server.py"]
}

Restart Claude Code. Fifteen tools appear, each prefixed mcp__agent-intern__:

• Antigravity (5): antigravity_ask, antigravity_continue, antigravity_image, antigravity_image_swarm, antigravity_status
• Codex (3): codex_ask, codex_continue, codex_status
• Copilot (3): copilot_ask, copilot_continue, copilot_status
• Cursor (3): cursor_ask, cursor_continue, cursor_status
• Shared (1): agent_swarm — fans a list of tasks out across all four backends in one run

The single-prompt tools — Antigravity, Codex, Copilot, and Cursor — take a watch=true flag for the live browser view (Watch mode).

[!NOTE] Your client learns how to use the bridge on its own. The server ships MCP instructions — a short routing guide (when to reach for each tool, which backend to pick, and to pass workspace so the sub-agent has repo context) that a client like Claude Code injects into the model's context on connect, as an "MCP Server Instructions" block. So the host model knows how and when to drive these tools without you explaining them — you can just ask for the result.

"Use antigravity_ask to summarize the README of this repo in three bullets." → Claude routes the prompt through the bridge, agy reads the file under the workspace root, and the answer comes back as a plain string. Swap in codex_ask, copilot_ask, or cursor_ask to have GPT, Copilot, or Cursor do the same.

Tools

🛰️ Antigravity

🤖 Codex

🐙 Copilot

✳️ Cursor

🐝 Shared

workspace defaults to the MCP server's current working directory. Point it at a real project dir for context-aware answers — every backend gives the model access to files under that root (Codex, Copilot, and Cursor honoring their sandbox).

antigravity_image forces agy to save to an explicit absolute path — without one, agy falls back to its own scratch dir (~/.gemini/antigravity-cli/scratch/). It then corrects the file extension to match the real bytes: agy's image model picks the format itself (JPEG for photo-like images, PNG for flat graphics), so a requested out.png may come back as out.jpg. The returned path always reflects the true format.

🤖 Codex bridge — the well-behaved sibling

codex exec writes its final message to a file the bridge asks for via -o/--output-last-message, so the answer comes back without any scraping (where agy needed a transcript workaround before 1.0.15 fixed its stdout). Three things make Codex worth reaching for over Antigravity:

• Real sandbox. sandbox accepts read-only (default — reads and answers, writes nothing), workspace-write (may edit files under the workspace), or danger-full-access (no sandbox — avoid). Unlike agy's no-op --sandbox, codex's -s actually enforces this. codex exec has no interactive approval gate, so this flag is your safety boundary — opt into write access deliberately.
• Model selection works. model maps to codex's -m. (agy's --model works in print mode too as of 1.0.16; all four backends now expose the same model knob.)
• Stronger reasoning. Codex is a coding agent, not an image model — there's no codex_image. Its strength is reasoning and real code/repo work; hand it the jobs that need a heavier model.

Auth. Uses your existing Codex login (ChatGPT account or API key). Run codex login once; check with codex_status. No new keys for the bridge to manage.

[!WARNING] codex exec runs the model as an autonomous agent with no interactive approval gate. The sandbox flag (default read-only) is the real boundary, but workspace-write / danger-full-access let it modify files — and a swarm runs N agents at once. Only use it with trusted prompts on trusted content.

🐙 Copilot bridge — GitHub's agentic coder

The GitHub Copilot CLI (copilot, from @github/copilot) is stdout-native like Codex: copilot -p "<prompt>" -s runs a prompt non-interactively and prints just the final answer to stdout, so the bridge reads it there — no scraping. What makes it worth reaching for:

• Model selection. model maps to copilot's --model; auto lets Copilot pick. Unlike the agy and cursor tools, the bridge can't validate this — copilot exposes no non-interactive model list — and the working set is account-dependent: on a Copilot Pro account here, auto worked while gpt-5.3-codex, claude-sonnet-4.6, and even GitHub's own --help example gpt-5.4 were all rejected as "not available". So omit model (account default) or pass auto unless you know your plan's ids; an unavailable one errors immediately with copilot's message, costing a call.
• Deterministic, race-free continue. copilot's --session-id <uuid> both sets a new session's id and resumes an existing one, so the bridge generates the UUID itself and pins it to the workspace — no rollout-scraping. After a restart it falls back to the newest on-disk session (~/.copilot/session-state/<id>/workspace.yaml) whose recorded cwd matches.
• Fast by default. Runs with --allow-all-tools --no-ask-user --no-auto-update, and disables copilot's builtin GitHub-API MCP (--disable-builtin-mcps) because its flaky HTTP connect can stall a call up to ~60 s. Set COPILOT_GITHUB_MCP=1 to keep it (for Copilot's issue/PR/repo tools).

Sandbox is best-effort, not enforced. Unlike Codex's OS sandbox, copilot's boundary is tool/path permissions. The sandbox knob maps to copilot flags for a uniform cross-backend field:

• read-only (default) — auto-approves tools so it runs headless, then denies the local write and shell tools (--deny-tool). Best-effort: it is not an OS sandbox, and network/MCP tools can still act. For a hard read-only boundary, use codex_ask instead.
• workspace-write — writes allowed, but file access stays confined to the workspace (no --allow-all-paths).
• danger-full-access — --allow-all (tools + all paths + all URLs). Avoid.

Auth. Uses your existing Copilot login — run copilot then /login once (stored in the OS credential store), or set COPILOT_GITHUB_TOKEN/GH_TOKEN/GITHUB_TOKEN for headless use. Check with copilot_status. If copilot isn't on PATH (the winget install can land off a stale PATH), set COPILOT_BIN to its full path — e.g. %LOCALAPPDATA%\Microsoft\WinGet\Packages\GitHub.Copilot_*\copilot.exe.

[!WARNING] copilot -p runs the model as an autonomous agent with --allow-all-tools (required to run headless). Its sandbox is best-effort tool/path permissions, not an OS sandbox — safer than agy, weaker than Codex's read-only. Only use it with trusted prompts on trusted content.

✳️ Cursor bridge — the widest model menu

Cursor's agent CLI (cursor-agent, from cursor.com/cli) is stdout-native like Codex and Copilot: cursor-agent -p --output-format text --trust "<prompt>" runs a prompt non-interactively and writes just the final answer to stdout, so the bridge reads it there — no scraping (--trust trusts the workspace so it won't block on a prompt). What makes it worth reaching for:

• The widest model menu. model maps to cursor's --model (e.g. auto, gpt-5.2, claude-opus-4-8-high, composer-2.5, cursor-grok-4.5-high) — GPT, Claude, Grok, and Composer in one place, ~190 ids at the time of writing. cursor bakes the effort and speed axes into the id (…-low / -high / -xhigh / -max, each with a -fast twin), and also accepts a bracket form on the family base, e.g. claude-opus-4-8[context=1m,effort=high]. The bridge validates against cursor-agent models and rejects a typo up front (like agy), accepting either an exact id or a family base. Omit model to use your Cursor account default. cursor reshuffles this list often — run cursor-agent models (or cursor_status) rather than trusting an example here.
• Deterministic, race-free continue. cursor-agent create-chat mints a fresh chat and prints its id, and -p --resume <chatId> resumes that exact chat — so the bridge mints the id itself, pins it to the workspace, and resumes deterministically (no rollout-scraping, same idea as Copilot's self-set session id). After a restart it falls back to the newest on-disk chat under ~/.cursor/chats/<md5(workspace)>/<chat-id>/ whose meta.json cwd matches (the chat-dir hash is itself md5 of the workspace path).

Sandbox is agent-enforced, not an OS sandbox. Like Copilot, cursor's boundary is which tools the agent can reach, not an OS jail. The sandbox knob maps to cursor's mode/force flags for a uniform cross-backend field:

• read-only (default) — --mode ask: the write and shell tools are unavailable, so cursor analyzes and answers but makes no edits (verified: it refuses to write files). Agent-enforced and best-effort — it is not an OS sandbox. For a hard read-only boundary, use codex_ask instead.
• workspace-write — --force: edits and commands allowed, file access rooted at --workspace.
• danger-full-access — --force --sandbox disabled (OS sandbox off). Avoid.

(Cursor also exposes an OS-level --sandbox enabled/disabled; the bridge drives the uniform field via mode/force.)

Auth. Uses your existing Cursor login — run cursor-agent login once (OS credential store), or set CURSOR_API_KEY for headless use. Check with cursor_status. If cursor-agent isn't reliably on PATH (the installer drops a cursor-agent.CMD shim a bare name can't launch on Windows), set CURSOR_BIN to its full path — mirrors the AGY_BIN/CODEX_BIN/COPILOT_BIN overrides.

[!WARNING] cursor-agent -p runs the model as an autonomous agent with --trust (and --force when writes are allowed). Its sandbox is agent-enforced (read-only makes the write/shell tools unavailable), not an OS sandbox — safer than agy, weaker than Codex's read-only. Only use it with trusted prompts on trusted content.

👁️ Watch mode — Agent Intern (experimental)

Pass watch=true to any single-prompt tool — antigravity_ask, antigravity_continue, antigravity_image, codex_ask, codex_continue, copilot_ask, copilot_continue, cursor_ask, or cursor_continue — to watch the agent work live in a little chat-style browser window called Agent Intern. The agent still runs headless; alongside it the bridge serves a tiny page on 127.0.0.1 and opens it in a small, chromeless app window that renders the exchange as a conversation: your prompt shows as a chat bubble, the agent's live steps stream in a collapsible "thinking" trace — its planner narration (▸), the real commands it runs ($), and completions (✓), read live (from agy's --output-format stream-json on 1.1.8+ — its transcript on older agy — or codex's / copilot's JSON event stream, or cursor's --output-format stream-json) — and the final answer arrives as a Markdown card (and, for antigravity_image with watch=true, the generated image shown inline). A *_continue run opens with the prior turns of the conversation shown as history, so it reads as one ongoing thread rather than a blank new window. (A watched cursor_continue is the exception — Cursor stores its transcript in an opaque SQLite blob, so its window opens without visible prior-turn history.)

text ask / continue (agy, codex, copilot, or cursor)	antigravity_image — image inline

_{Real captures — the agent runs headless while the Agent Intern window renders the exchange as a chat conversation: your prompt as a CLAUDE bubble, live steps (▸ narration · $ commands · ✓ completions) in a collapsible trace, then the final Markdown answer or inline image.}

• Cross-platform & best-effort. Prefers a Chromium browser (--app mode) for the windowed look; falls back to a normal browser window. If nothing can open, the run still completes and returns normally.
• Window size. Set AGY_WATCH_WINDOW_SIZE (e.g. AGY_WATCH_WINDOW_SIZE=480,700) to resize the window; default is 560,760. Press Enter / Esc in the window to close it.
• One window, reused — but concurrent runs stay separate. Repeated sequential watch calls reuse the already-open window instead of stacking a new one (the open page resets itself for the new run; the swarm dashboard rebuilds for the new fan-out). A run that starts while another watched run is still working gets its own window instead — so two concurrent single-worker runs (e.g. a codex_ask and a copilot_ask at once) each stream into their own view and never clobber each other. If you closed the window, the next run opens a fresh one. Set AGY_WATCH_ALWAYS_NEW=1 to force a new window every time.
• Chat layout & history. Prompts render as chat bubbles (labelled CLAUDE, since the MCP client writes them) — long ones clamp to a few lines with a show more / show less toggle — and answers as Markdown cards tagged with the backend (AGY / CODEX / COPILOT / CURSOR). A *_continue run seeds the window with the conversation's prior turns, read from each backend's own session store (agy's transcript, codex's rollout, copilot's events.jsonl; Cursor's store is opaque, so a watched cursor_continue opens without visible history). The swarm's per-worker detail window uses the same chat design for its one task.
• Progress, keyboard & copy. Each panel shows a time progress bar (elapsed / timeout). The swarm dashboard adds an overall done/total bar and per-row time bars; use ↑/↓ to select a worker and ↵ to open its detail window. Answers render as Markdown with a copy button, and a "jump to latest" badge appears if you scroll up.
• Coarse, not token-level. The backends flush their step stream in chunks, so you get a handful of live steps, not character streaming. The returned value is identical to the non-watch call. Nothing is sent anywhere but your own machine.

🐝 Swarm — run agents in parallel

agent_swarm fans a list of tasks out to workers that run truly concurrently (capped at max_concurrency, default 4), then returns every worker's result in one block. Each task names its own backend, so a single swarm can mix Antigravity (Gemini), Codex, Copilot, and Cursor workers — hand the reasoning-heavy jobs to Codex, Copilot, or Cursor and the quick ones to Gemini, all at once. Good for independent sub-tasks: summarise N files, ask the same question about N repos, fix N bugs. (antigravity_image_swarm stays separate — it generates N images, and only agy has an image model.)

agent_swarm(tasks=[
  {"backend": "antigravity", "prompt": "Summarise src/auth.py in 2 bullets."},
  {"backend": "codex", "prompt": "Find and fix the failing test in tests/",
   "sandbox": "workspace-write", "workspace": "./repo"},
  {"backend": "copilot", "prompt": "Explain what src/api.py exposes.",
   "sandbox": "read-only", "workspace": "./repo"},
  {"backend": "cursor", "prompt": "Draft a docstring for src/utils.py.",
   "model": "auto", "workspace": "./repo"},
])

_{agent_swarm(..., watch=true) — one row per worker (with a backend badge); the done/total bar climbs as workers finish. Click a row (or ↑/↓ then ↵) to pop that agent into its own window.}

How it stays correct under concurrency. The single-agent agy tools serialize through a lock because agy rewrites last_conversations.json on every call, so concurrent runs sharing one state dir would race. The swarm sidesteps this: each agy worker runs with its own isolated HOME/USERPROFILE, so agy's brain/, cache/, and last_conversations.json never collide — no lock needed. Auth still works because agy reads it from the OS credential store, not from ~/.gemini (verified on agy 1.0.9). Codex, Copilot, and Cursor workers need no such isolation — each is a fresh one-shot (codex exec with its own -o file; copilot -p with its own self-set session id; cursor-agent -p with its own minted chat id). Each worker's cwd is its real workspace, so file access is unchanged. Measured ~2.8× speedup at 3 agy workers (the AI Pro backend does not serialize per-account); higher max_concurrency trades quota/rate-limit pressure for wall-clock.

• Per-task fields — backend (antigravity/codex/copilot/cursor) and prompt are required; workspace defaults to the server cwd; sandbox and model apply to Codex, Copilot, and Cursor (ignored for Antigravity). Swarm workers are one-shot — there is no *_continue for a swarm worker's session.
• Error isolation — a worker that fails is reported in place; the others still return.
• watch=true — opens a thin live Agent Swarm dashboard (one row per worker, with a backend badge, repo, prompt, and latest step). Click a row to pop that agent into its own window streaming its full step log.

[!WARNING] A swarm launches N unsandboxed agents at once — N× the prompt-injection "lethal trifecta" surface of a single call (see Security). Only use it with trusted prompts on trusted content. Codex workers honor their enforced sandbox; Copilot and Cursor workers honor their best-effort sandbox; Antigravity workers have no real boundary.

Model & auth

⚠️ Security

All four backends run the model as an autonomous agent. The difference is whether you get a real boundary: Codex enforces one, Copilot and Cursor offer best-effort ones, Antigravity offers none.

Antigravity — no usable boundary

agy -p executes its own tools — reading and writing files, running shell commands, reaching the network — with no approval gate. Through agy 1.1.2 that was simply how print mode worked, with no opt-out at all. As of 1.1.3 it is a choice the bridge makes: agy finally gates headless tool calls, and the bridge deliberately opts out with --dangerously-skip-permissions, because a gated -p can do no useful work (it soft-denies even a plain file read, and print mode has no way to prompt). The posture below is therefore unchanged — assume every call runs arbitrary code with your privileges. Re-verified empirically on agy 1.0.9 / Windows, with the 1.1.3 amendment noted:

• Print mode runs out-of-workspace file writes and live network fetches even without --dangerously-skip-permissions — that flag was a no-op for -p through 1.1.2. As of 1.1.3 it is load-bearing: without it every tool-using call is soft-denied, and the bridge now always passes it (it must precede -p, whose value is the prompt). There is still no agy flag that makes print mode both safe and useful.
• agy 1.0.5 integrated a permission system (its logs show toolPermission=request-review), but it still does not gate print-mode execution — a fresh -p run created a file outside the workspace with no prompt. agy 1.0.12 reshuffled how that permission config merges (per-project files under ~/.gemini/config/projects/ now take precedence over ~/.gemini/antigravity-cli/settings.json), and 1.0.13 made "Always Approve" rule matching strict (non-regex) by default with a regex: opt-in and relaxed its redirection checks — but those are config/interactive-approval changes, they add no print-mode approval gate, and the bridge reads none of it.
• --sandbox is not a usable boundary. agy 1.0.6 fixed its propagation into -p (the 1.0.6/1.0.7 changelog calls this "sandbox isolation correctly enforced") and it now does block terminal/ shell command execution — but re-verified on 1.0.9 that it leaves the write_to_file tool and network wide open: under --sandbox the model still wrote a file outside its workspace. agy 1.0.9 hardened the sandbox's command path (stricter exact-match command checks; .git added to its dangerous-paths list), but none of that closes the out-of-workspace write_to_file hole. On top of that, a --sandbox run whose blocked terminal command halts it writes no JSONL transcript (only the SQLite .db, re-confirmed on 1.0.9). The bridge can now read that .db, but still never passes --sandbox — it's no boundary, with file writes and network left open.

Codex — a real sandbox you should use

codex exec also has no interactive approval gate, but its sandbox flag is a genuine boundary that codex enforces:

• read-only (default) — reads and answers; writes nothing. Safe for untrusted questions on trusted content.
• workspace-write — may edit files under the workspace. Opt in deliberately, per task.
• danger-full-access — no sandbox at all. Avoid.

Because there's no approval prompt, the flag you pass is the safety decision — choose it per call.

Copilot — best-effort, not an OS sandbox

copilot -p runs headless with --allow-all-tools (required — otherwise it blocks on per-tool permission prompts). Its sandbox maps to copilot's tool/path permission flags, which are a real-ish but not enforced boundary:

• read-only (default) — auto-approves tools to run headless, then denies the local write and shell tools (--deny-tool). Blocks local file edits and command execution, but it is not an OS sandbox: other tools (including network/MCP) can still act. Weaker than Codex's read-only.
• workspace-write — writes allowed, but file access stays confined to the workspace (no --allow-all-paths).
• danger-full-access — --allow-all (tools + all paths + all URLs). Avoid.

For a hard read-only boundary, prefer codex_ask.

Cursor — best-effort, agent-enforced

cursor-agent -p runs headless with --trust (and --force when writes are allowed). Its sandbox maps to cursor's mode/force flags — an agent-enforced, not OS-level, boundary:

• read-only (default) — --mode ask: the local write and shell tools are unavailable, so cursor analyzes and answers but makes no edits (verified: it refuses to write files). Like Copilot, this is agent-enforced and not an OS sandbox. Weaker than Codex's read-only.
• workspace-write — --force: edits and commands allowed, file access rooted at --workspace.
• danger-full-access — --force --sandbox disabled (OS sandbox off). Avoid.

For a hard read-only boundary, prefer codex_ask.

What that means for you

• The workspace argument is only a starting context, not a security boundary — Antigravity can and does act outside it; Codex is bounded by its enforced sandbox; Copilot by its best-effort tool/path permissions; Cursor by its agent-enforced mode/force.
• An Antigravity call effectively runs arbitrary code with your user privileges. A Copilot or Cursor call does too outside its best-effort denials; a Codex call does unless you keep it at read-only.
• Only invoke these with trusted prompts on trusted content. Untrusted input here is the classic prompt-injection lethal trifecta: private-data access + code execution + network egress.
• For real isolation, run the whole bridge inside a container or VM.

The bridge itself does only cross-platform filesystem reads under ~/.gemini/antigravity-cli/, ~/.codex/, ~/.copilot/, and ~/.cursor/ — no private APIs, no token theft. The risk above is entirely in what the sub-agents are allowed to do.

FAQ

Status & caveats

• ✅ Verified on agy 1.1.7 and 1.1.8 — nothing broke, and 1.1.8 made the bridge sturdier. 1.1.8 gave print mode an --output-format flag (text | json | stream-json). The existing text path was confirmed live on 1.1.8 first (ask, pinned continue, and --model all clean), then the bridge switched its plain ask/continue calls to --output-format json, because reading a contractual response field beats trusting the layout of bare text. The real prize is the conversation_id agy returns with it: the bridge records it and pins a later antigravity_continue to exactly the conversation it last ran in that workspace, instead of inferring it from last_conversations.json — shared state agy rewrites for every session, including your own interactive TUI work in the same folder. Practical difference: antigravity_continue now resumes the bridge's own thread, where before it could land on a conversation you'd since started in the Antigravity TUI. Older agy is unaffected — the flag is version-gated (pre-1.1.8 has no such flag), and any non-JSON stdout falls back to the previous text path, so a silently-ignored flag degrades instead of crashing. VERIFIED_AGY_VERSION → (1, 1, 8). Not adopted: --json-schema (works; nothing here needs it). Nothing else in 1.1.7/1.1.8 reaches the bridge — the rest is interactive-TUI, plugin-hook, and MCP-client work.
• ✅ Watch mode reads agy's live event stream instead of scraping its transcript. On agy 1.1.8+ the watched runners request --output-format stream-json and consume agy's typed init / step_update / result events straight off stdout. Verified before the rewrite that they arrive incrementally (a 17 s run spread its 18 events over 12.4 s), and confirmed live that a watched run's step count grows while agy works. The stream carries the real command as a nested object (the transcript stored tool args JSON-encoded inside a string), streaming text fragments, and a conversation_id — so a watched run now pins later continues just like a plain one. This retires the timer-based transcript polling, which matters beyond tidiness: agy has announced JSONL is being replaced by SQLite, and watch was the last path that would have broken when it goes. Pre-1.1.8 agy keeps the original transcript path, re-verified live.
• ⚠️ Behavior change: multi-step answers now include the model's narration. agy's response is the whole turn; the old transcript scrape returned only the last planner response. Identical for a single-step ask, different for a chatty multi-step one (one measured run: 297 chars vs 128, the full answer ending in the old one). The full turn is now returned on every path — response is agy's own contract for what the turn produced, and the old last-step rule silently dropped content whenever the model did the work and then closed with a short "Done."
• ✅ Re-verified on agy 1.1.6 — no code change needed. 1.1.6 added the gemini-3.6-flash family to agy models and moved the settings.json default to Gemini 3.6 Flash (High); the default path and --model gemini-3.6-flash-high both round-tripped clean, and the JSONL + SQLite read paths still match agy's unchanged conversation schema. Its one bridge-adjacent fix — print mode now surfacing the real conversation-creation error instead of a misleading "no active conversation" — only improves the diagnostic the bridge already reads on failure. Everything else (Markdown custom agents, /copy and /codesearch polish, background-task hardening) is interactive-TUI or client-side work that doesn't reach the bridge. Docs-only: the model list and default examples now name the 1.1.6 slugs, and the guard test advertises gemini-3.6-flash-high against the live list.
• ⚠️ Verified on agy 1.1.5 — it renamed every model, so old model values now fail. 1.1.5 replaced agy's human-readable model labels with stable slugs, and agy models reports only those: "Gemini 3.1 Pro (High)" is now gemini-3.1-pro-high, and the Claude entries are claude-sonnet-4-6 and claude-opus-4-6-thinking (the mapping is not 1:1 — check agy models, or antigravity_status, for the current eight). Since the bridge validates model against agy models, an old label is rejected up front with the valid list — you lose the call, not your money, and never silently run on the wrong model. Pass slugs and you're fine. Nothing in the bridge's machinery needed changing (validation was always format-agnostic — which is exactly why the entire test suite stayed green while every documented example went stale), so this release is docs plus one new test that checks the models we advertise against the live agy models list. Everything else in 1.1.5 is interactive-TUI, MCP-client, or background-task work that doesn't reach the bridge; its new --effort flag is a second axis we don't pass, because the slug already pins the effort variant.
• ✅ Verified on agy 1.1.4 — no code change was needed. 1.1.4 relaxed the 1.1.3 headless gate so that -p now honors your persisted settings.json policies (permissions, file access, sandbox mode, auto-execution, artifact review) instead of blanket-denying. --dangerously-skip-permissions still overrides those policies, so the flag stays load-bearing and stays exactly where it is — re-verified live against a workspace deliberately absent from trustedWorkspaces, with a permissions.allow list naming neither file nor command access: a workspace file read returned the right contents, and a terminal command and a file write both executed. Worth knowing: that flag is now the only thing between a bridge call and your own settings.json policy, and dropping it would get you whatever that file says rather than 1.1.3's deny-everything. 1.1.4 also stopped /btw side-questions from leaking into the conversation list as duplicates carrying the parent's title — that list is what conversation pinning reads, so one way to resume the wrong thread is gone.
• ✅ Verified on agy 1.1.3 — base dir, last_conversations.json (still keyed by workspace path), the brain/.../transcript.jsonl path, the transcript schema, and the -p/-c/--print-timeout flags are all unchanged; a live antigravity_ask + conversation-pinned antigravity_continue round-trip returns clean over stdout and antigravity_status diagnostics pass. 1.1.3 broke and the bridge fixed the one thing that mattered: headless -p no longer auto-approves tool calls, it soft-denies them (print mode cannot prompt), so without a flag even "read pyproject.toml and report the version" returned nothing — exit 0, empty stdout, the reason only on stderr. The bridge now passes --dangerously-skip-permissions on every agy path, which restores file writes, terminal commands and workspace reads (a live bridge round-trip reads this repo's real version again). The flag must precede -p, whose value is the prompt — otherwise the flag becomes the prompt and the task is silently dropped. 1.1.2 also made an unresolvable --model hard-fail in -p instead of silently falling back to the settings.json default (the bridge's validate_model still rejects a typo up front, without spending a call). 1.1.0's execution-mode system (--mode, request-review) remains a no-op for the bridge: -p is spawned with DEVNULL stdin, so that interactive gate never engages. --sandbox behavior is likewise unchanged (blocks the terminal, not file writes). The print-mode stdout path (fixed on 1.0.15, Windows) still applies; the transcript stays the fallback.
• ✅ Verified on codex-cli 0.144.1 — codex exec, -o/--output-last-message, codex exec resume, the --json event stream, and the ~/.codex/sessions/.../rollout-*.jsonl layout the continue path reads are all in place; a live codex_ask round-trip + codex_status pass. (Bumped from the 0.141.0 baseline: flags, session layout and the round-trip all re-verified unchanged.)
• ✅ Verified on copilot 1.0.69 — copilot -p -s (clean stdout answer), --session-id set-then-resume, --model, --output-format json (watch stream), and the ~/.copilot/session-state/<id>/workspace.yaml layout the continue fallback reads are all in place; live copilot_ask / copilot_continue round-trips + a mixed agent_swarm pass. (Bumped from 1.0.68: 1.0.69 adds a --resume convenience flag the bridge doesn't need; --session-id still both sets a fresh id and resumes it — re-verified live, ACK then codeword recall.)
• ✅ Verified on cursor-agent 2026.07.08 — cursor-agent -p --output-format text --trust (clean stdout answer), create-chat + -p --resume <id>, --model (validated against cursor-agent models), --output-format stream-json (watch stream), and the ~/.cursor/chats/<md5(workspace)>/<chat-id>/meta.json layout the continue fallback reads are all in place; live cursor_ask / cursor_continue round-trips + a mixed agent_swarm pass. (2026.07.09 is installed and cursor_status — found, logged in, chats dir — passes with flags/layout intact; a fresh live round-trip was deferred, Cursor usage limit reached.)
• 🖥️ Console-detach — before 1.0.15 agy -p wrote its answer to the controlling terminal, not stdout; under a TUI that text leaked into the host's prompt (seen on 1.0.9). 1.0.15 fixed this on Windows (stdout now carries the answer), but the bridge still spawns agy detached (CREATE_NO_WINDOW / a new POSIX session), which prevents the leak on older/other platforms and is harmless on 1.0.15+.
• 💾 SQLite migration — handled — agy still dual-writes a .db per conversation; on the fallback path, when the JSONL transcript is absent (already true for --sandbox runs, and the announced future default) _read_response falls back to reading the .db, verified to match across 100+ conversations. See the FAQ.
• 🐛 agy stdout bug — fixed on 1.0.15 — -p now prints the clean answer to stdout in a non-TTY subprocess (Windows), so the bridge prefers stdout and only scrapes the transcript when stdout is empty (older agy, non-Windows, or --sandbox). (Codex and Copilot never had this problem — both are stdout-native.)
• 👁️ Watch mode is experimental — pass watch=true to any single-prompt tool to open the Agent Intern window and watch the agent work live (coarse steps; image shown inline). Best-effort and cross-platform; see Watch mode.
• 🔒 Sandbox — agy's --sandbox blocks only shell commands, so it's no boundary and the bridge never passes it. Codex's sandbox is real and enforced — use it; default read-only. Copilot's sandbox is best-effort (tool/path denials, not an OS sandbox); default read-only. Cursor's sandbox is agent-enforced (mode/force; read-only = --mode ask makes write/shell unavailable, not an OS sandbox); default read-only. See Security.

Requirements

• Python 3.10+
• For the Antigravity tools: agy 1.0.0+ on PATH (state-file layout re-verified on 1.0.15) and an active Antigravity / AI Pro session
• For the Codex tools: codex on PATH and logged in (codex login) — verified on codex-cli 0.144.1
• For the Copilot tools: copilot on PATH and logged in (copilot → /login, or a COPILOT_GITHUB_TOKEN/GH_TOKEN env) — verified on copilot 1.0.69
• For the Cursor tools: cursor-agent on PATH and logged in (cursor-agent login, or a CURSOR_API_KEY env) — verified on cursor-agent 2026.07.08

Each backend is independent — install only the CLI(s) you plan to use; the other tools simply report "not found" via their *_status tool.

[!TIP] If agy isn't reliably on PATH (e.g. a new terminal or reboot drops it on Windows), set the AGY_BIN env var to its full path and the bridge will use that instead of "agy" — e.g. AGY_BIN=%LOCALAPPDATA%\agy\bin\agy.exe. Likewise, set CODEX_BIN if codex isn't reliably on PATH (the native Windows installer puts it under %LOCALAPPDATA%\Programs\OpenAI\Codex\bin\), and COPILOT_BIN if copilot isn't (the winget install lands under %LOCALAPPDATA%\Microsoft\WinGet\Packages\GitHub.Copilot_*\copilot.exe). Finally, set CURSOR_BIN if cursor-agent isn't reliably on PATH (the installer drops a cursor-agent.CMD shim a bare name can't launch on Windows).

The bridge uses only cross-platform Python (Path.home(), subprocess) and reads paths under ~/.gemini/antigravity-cli/, ~/.codex/, ~/.copilot/, and ~/.cursor/, which the CLIs write the same way on every OS. Developed and verified on Windows; macOS and Linux should work unmodified provided the CLIs run there. If you test it on those platforms, please open an issue / PR to confirm.

🌐 Community & Acknowledgments

• Qiita (Japan): A huge thanks to @fallout and the Japanese developer community for featuring this project and providing invaluable feedback!
  • Detailed Hybrid Setup Guide (Claude Code × Antigravity CLI)
  • Quick Installation Guide

💡 Path Resolution Fix: Thanks to their community's real-world testing, we identified and resolved a Windows PATH edge case where the MCP server inherits a stale PATH at startup and can't find agy. The AGY_BIN environment-variable fallback was implemented directly inspired by their report!

License

MIT. Do whatever you want with it.