Two coding agents. Two completely different philosophies. Reasonix bets everything on DeepSeek’s prefix cache to deliver absurdly cheap agentic coding. Antigravity CLI (agy) gives you Google’s multi-model platform with Gemini, Claude, and GPT-OSS all behind one interface.

Which one fits your workflow? Let’s break it down with real numbers.

Quick Comparison Table

Feature	Reasonix	Antigravity CLI (agy)
Cost model	Pay-per-token (DeepSeek API)	$20/mo Pro, $100/mo Ultra
Models	DeepSeek V4-Flash, V4-Pro	Gemini 3.5 Flash, 3.1 Pro, Claude Sonnet 4.6, Opus 4.6, GPT-OSS 120B
Open source	Yes (MIT, TypeScript)	No (closed source, Go binary)
Model selection	/pro command for V4-Pro	Server-side routing (no flag)
Context window	DeepSeek native (128K)	Varies by model (up to 2M with Gemini)
Platform	Node.js >= 22	Go binary (any OS)
MCP support	Yes	Yes
Plan mode	Yes	No (but has headless --print)
Headless/CI	Via plan mode	--print flag
Session persistence	Yes	--continue flag
Hooks	Yes	No
Skills/Memory	Yes	No
Web search	Yes	Yes
Desktop app	Yes	No
GitHub stars	9K	N/A (closed source)

For full details on each tool, see the Reasonix complete guide and the Antigravity CLI complete guide.

Installation

Getting started with either tool takes seconds.

Reasonix:

npm install -g reasonix
# or without global install
npx reasonix code

Requires Node >= 22 and a DeepSeek API key.

Antigravity CLI:

curl -fsSL https://antigravity.google/cli/install.sh | bash

Requires a Google AI Pro ($20/mo) or Ultra ($100/mo) subscription.

Cost Analysis: Real Scenarios

This is where the two tools diverge most dramatically. Reasonix uses pay-per-token pricing with aggressive cache optimization. Antigravity uses a subscription with compute-based quotas.

Light Use (hobby projects, 1-2 hours/day)

Reasonix: Using V4-Flash at $0.07/$0.28 per 1M tokens (input/output), a light user consuming maybe 50M tokens/month lands around $3-5/month. The prefix cache optimization means most of your input tokens hit cache at massive discounts.

Antigravity: $20/month flat. The 5-hour rolling window and weekly cap won’t matter at this usage level. You get access to all models regardless.

Winner: Reasonix by a wide margin. You’re paying 75-85% less for light use.

Heavy Use (full-time development, 6-8 hours/day)

Reasonix: Heavy users report around 435M tokens/month. Thanks to the 99.82% cache hit rate, this costs roughly $12. Without cache optimization, the same usage would cost $61. See how the prefix cache works for the technical details.

Antigravity: $20/month Pro handles most heavy users fine since Google 3x’d the rate limits permanently. The 5-hour rolling window resets, so sustained use across a workday is viable. Power users hitting the weekly cap might need Ultra at $100/month.

Winner: Reasonix at $12 vs $20. But Antigravity gives you model diversity for that $20.

Autonomous Agent Use (CI/CD, batch processing, overnight runs)

Reasonix: Plan mode lets you queue up work. Costs scale linearly with tokens consumed. An overnight batch processing 2B tokens would cost around $55 with cache optimization.

Antigravity: --print headless mode works in CI pipelines. But the compute-based quota means long autonomous runs eat into your rolling window fast. Ultra at $100/month gives you 5x the headroom, but there’s still a ceiling.

Winner: Reasonix for truly unlimited autonomous use. Antigravity’s quota model creates a hard ceiling that subscriptions can’t fully solve.

The DeepSeek V4-Pro Factor

When you need maximum reasoning power, Reasonix’s /pro command switches to V4-Pro at $0.435/$0.87 per 1M tokens. That’s still cheap compared to frontier models, especially with the 75% permanent discount DeepSeek announced. Antigravity routes to Claude Opus 4.6 or Gemini 3.1 Pro automatically for complex tasks, but you can’t control which model handles what.

Architecture: Two Different Bets

Reasonix: Cache-First Single-Model

Reasonix’s entire architecture is engineered around one insight: DeepSeek’s prefix cache is incredibly stable. With a 99.82% cache hit rate, most of your context window is served from cache at a fraction of the cost.

This means:

• Conversations stay cheap even as context grows
• Persistent sessions don’t penalize you on cost
• The agent can maintain massive context without budget anxiety

The tradeoff is clear: you get one model provider. DeepSeek V4-Flash for speed, V4-Pro for power. That’s it. No fallback if DeepSeek has an outage.

Antigravity: Multi-Model Platform

Antigravity takes the opposite approach. Google routes your requests across five different models based on task complexity. You don’t choose. The platform decides.

This means:

• Simple tasks get fast, cheap models (Gemini 3.5 Flash)
• Complex reasoning gets frontier models (Claude Opus 4.6, Gemini 3.1 Pro)
• You benefit from model diversity without managing it

The tradeoff: no transparency on which model handles what, shared quota across all models, and a subscription ceiling that limits autonomous use.

For a comparison of Antigravity against another tool, see Grok Build vs Antigravity CLI.

Feature Comparison

MCP (Model Context Protocol)

Both tools support MCP for connecting to external tools and data sources. Reasonix’s implementation is community-driven and well-documented. Antigravity’s MCP support works but has less community tooling around it given the closed-source nature.

Plan Mode vs Headless

Reasonix plan mode lets you describe what you want, review the plan, then execute. It’s interactive by default but can be scripted.

Antigravity --print is pure headless. Feed it a prompt, get output to stdout. No interaction, no approval step. Great for CI, less useful for iterative development.

Sessions

Reasonix has built-in persistent sessions with memory. Your agent remembers past conversations, learned skills, and project context across sessions.

Antigravity uses --continue to resume the last session. It’s simpler but less powerful. No cross-session memory or skill accumulation.

Hooks and Skills

Reasonix has hooks (trigger actions on events) and skills (reusable agent behaviors). These are unique to Reasonix and have no equivalent in Antigravity. If you’re building custom agent workflows, this matters.

Permissions

Reasonix asks for confirmation on destructive actions by default.

Antigravity has --dangerously-skip-permissions for fully autonomous operation. The flag name tells you everything about Google’s opinion on using it.

Autonomous/Headless Use

Both tools support unattended operation, but the experience differs significantly.

Reasonix autonomous workflow:

# Plan mode for batch operations
npx reasonix code --plan "Refactor all API routes to use the new auth middleware"

No quota ceiling. Costs scale with usage. You can run it overnight without worrying about hitting a wall.

Antigravity headless workflow:

# Headless mode for CI/CD
agy --print "Generate unit tests for src/auth/" > tests.ts
# Skip all permission prompts
agy --dangerously-skip-permissions --print "Fix all lint errors"

Clean, scriptable, but bounded by your subscription’s compute quota. Heavy CI usage on Pro ($20/mo) will hit the weekly cap. Ultra ($100/mo) gives breathing room but still has limits.

Verdict by Use Case

Choose Reasonix if:

• Cost efficiency is your top priority
• You’re comfortable with DeepSeek as your sole model provider
• You want open source you can inspect and extend
• You need unlimited autonomous agent runs
• Hooks, skills, and memory matter to your workflow
• You prefer pay-per-use over subscriptions

Choose Antigravity CLI if:

• You want model diversity without managing multiple API keys
• Predictable monthly billing matters more than absolute cheapest cost
• You need access to Claude Opus 4.6 and Gemini 3.1 Pro through one interface
• Your team is already in the Google ecosystem
• You prefer a managed platform over self-hosted tooling
• Simple headless CI integration with --print fits your pipeline

Choose both if:

• You use Reasonix for daily development (cheap, fast, persistent)
• You use Antigravity for tasks that benefit from model diversity or when DeepSeek is down

FAQ

Is Reasonix really only $12/month for heavy use?

Yes. The 99.82% prefix cache hit rate on DeepSeek means most input tokens cost a fraction of list price. Users consistently report $10-15/month for full-time development use. See the prefix cache deep dive for the math.

Can I choose which model Antigravity uses?

No. There’s no model selection flag. Google routes requests server-side based on task complexity. You can’t force it to use Claude Opus 4.6 for everything, for example.

What happens when I hit Antigravity’s quota limit?

Your requests queue or get rejected until the 5-hour rolling window resets. Google recently 3x’d the limits, which helps, but heavy autonomous use can still hit the ceiling. Ultra ($100/mo) gives 5x Pro limits.

Does Reasonix work with models other than DeepSeek?

No. It’s built specifically around DeepSeek’s architecture and prefix cache behavior. The entire cost advantage depends on this tight coupling. If you want multi-model, look at Antigravity or other tools.

Which is better for CI/CD pipelines?

Antigravity’s --print mode is more straightforward for CI. Pipe in a prompt, get output on stdout. Reasonix’s plan mode works but requires more scripting to integrate cleanly. However, Reasonix has no usage ceiling, which matters for high-volume CI.

Can I use both tools on the same project?

Absolutely. They don’t conflict. Use Reasonix for daily coding (cheap, fast) and Antigravity when you want a second opinion from a different model family or need its headless mode in CI.

Is Antigravity CLI the same as Gemini CLI?

Antigravity replaces Gemini CLI, which sunsets June 18, 2026. It launched at Google I/O on May 19, 2026. Same concept (terminal AI agent) but rebuilt as a multi-model platform. See the Antigravity complete guide for migration details.

What are the system requirements?

Reasonix needs Node.js >= 22. Antigravity is a standalone Go binary that runs on macOS, Linux, and Windows with no runtime dependencies.

Which has better context handling for large codebases?

Reasonix’s cache-first architecture means large contexts stay cheap. You can maintain huge conversation histories without cost anxiety. Antigravity can access up to 2M tokens with Gemini models, but that burns through compute quota faster. For sustained work on large codebases, Reasonix’s economics win.