Gemma 4 Implicit Caching in Antigravity: Cut Your Credit Costs by 40% Without Changing a Line of Code

If you've been using Antigravity on a large codebase, you've probably felt that nagging sensation: your credits draining every time you attach the same file again. "I just gave you this…" — and yet, out of habit, you keep re-attaching it anyway.

Here's what most people don't realize: Gemma 4 has a built-in mechanism called Implicit Caching that automatically reuses repeated context within the same session. Once you understand how it works and design your workflow around it, you can cut credit consumption by 30–60% without installing anything new or changing any settings.

This article breaks down the practical patterns for Antigravity, including where caching works well and — just as importantly — where it quietly breaks down.

What Implicit Caching Actually Does (And Why Gemma 3 Didn't Have It)

With Gemma 3 and earlier models, every prompt was processed from scratch. If you had a 10,000-token codebase in your context and sent 10 messages, you were paying for 100,000 tokens of processing. There was no memory of what had already been read.

Gemma 4's Implicit Caching changes this: if the beginning of your current prompt matches the beginning of your previous request, that portion is served from cache rather than reprocessed. The word "implicit" means you don't have to ask for it — it happens automatically.

The conditions for caching to kick in:

• Same chat session (cache doesn't persist across sessions)
• The prefix of the prompt must be identical to the previous request
• The cached portion must exceed the minimum threshold (typically 1,024+ tokens)

The most common way people accidentally break caching is by starting each message differently — adding a timestamp, a "today I'm working on X" note, or any variation at the top. Even a small change to the prefix resets the cache entirely.

What This Looks Like in a Real Antigravity Workflow

Here's a concrete comparison of the same three-step task, done with and without caching awareness:

Without caching awareness:

Message 1: "Look at this file and fix the type errors" (attaches fileA)
Message 2: "Now improve the performance of this file" (re-attaches fileA)
Message 3: "Add tests for this file" (re-attaches fileA)

FileA gets fully processed three times.

With caching in mind:

Message 1: "@fileA — first, fix the type errors"
Message 2: "Now improve the performance"  (file stays in context)
Message 3: "Add tests for the main function"  (same)

By @mentioning the file once and letting it stay in context, Gemma 4 can reuse the cached representation for messages 2 and 3. In my own testing on a 1,500+ line TypeScript file over a 10-message session, keeping the cache intact resulted in roughly 2–3x faster responses and around 40% fewer credits consumed. Your mileage will vary based on file sizes and how often you refresh context.

Designing Your Project to Maximize Cache Efficiency

The core principle of Implicit Caching is "stable prefix, variable suffix." Whatever stays constant in your prompts should come first; whatever changes per request should come last.

The most powerful tool Antigravity gives you for this is ANTIGRAVITY.md — a file you place in your project root that gets automatically prepended to every chat. As long as this file doesn't change between sessions, Gemma 4 will have a stable, cacheable prefix on every single request.

Here's an example of a well-structured ANTIGRAVITY.md that promotes consistent caching:

# Project Context (ANTIGRAVITY.md)
 
## Architecture
- Next.js 16 App Router + TypeScript
- Cloudflare Workers deployment
- Supabase (DB) + Stripe (payments)
 
## Coding Rules
- Type safety is the top priority — no `any`
- Keep Server Components and Client Components clearly separated
- Use the Result pattern for all error handling
 
## Key Files
- src/lib/auth.ts — authentication logic
- src/lib/stripe.ts — Stripe integration
- src/types/index.ts — shared type definitions

Once this is in place, you rarely need to explain your project from scratch. The consistent prefix means Gemma 4 can cache your project context across messages, even across different features you're working on in the same session.

Four Patterns That Silently Kill Your Cache

In practice, there are a few recurring ways that caching breaks down without obvious warning signs:

Pattern 1: Frequently creating new chat sessions

Every "New Chat" in Antigravity starts a fresh session with no cached context. If you're working on the same feature, there's often no reason to start a new chat — staying in one session throughout a feature build is the single highest-leverage habit change you can make.

Pattern 2: Writing different opening lines each message

"Good morning, today I'm continuing with the auth system…" — that kind of prefix variation kills caching immediately. Let ANTIGRAVITY.md handle the stable intro; keep your messages focused on the specific task at hand.

Pattern 3: Switching models mid-session

Switching from Gemma 4 to another model (like Gemini 2.5 Pro) partway through a chat can reset the cache. If you need to compare models, do it in separate sessions rather than toggling back and forth.

Pattern 4: Blowing past the context window

Gemma 4 supports up to 1 million tokens, but once older messages start getting evicted to make room, the cached prefix changes. For very long sessions, it's worth periodically distilling key decisions back into ANTIGRAVITY.md and starting fresh — you'll preserve the stable prefix and avoid the performance degradation that comes with a bloated, shifting context.

Where Caching Has the Most Impact

Not all development tasks benefit equally. The scenarios where Implicit Caching has the most noticeable effect:

Large schema files with repeated queries: Database schemas and shared type definitions are ideal candidates. Once loaded, every subsequent query generation, type fix, or test addition runs against cached context. The performance difference is immediately noticeable.

Multi-step refactoring sessions: When you're incrementally refactoring a component — moving logic, splitting files, updating tests — keeping the same files in context throughout the session lets caching do its job. Avoid re-opening or re-attaching files you're actively working on.

Documentation generation: If you're generating README sections or API docs by repeatedly asking Gemma 4 to describe different parts of the same codebase, the stable codebase context caches well across those requests.

Where caching adds less value: quick one-off questions about completely different files, or sessions where you're constantly switching between unrelated parts of the codebase. In those cases, you're not establishing a stable prefix, so there's nothing to cache.

Two Things You Can Change Starting Tomorrow

Everything described here requires zero configuration changes or additional tooling. The only things worth adjusting are your habits:

1. Invest in your ANTIGRAVITY.md: Centralize your project's stable information — architecture decisions, coding rules, key file descriptions — so every session starts with a consistent, cacheable prefix.
2. Commit to longer sessions: Resist the habit of starting a new chat for every small task. Working within the same session for a full feature (or even a full work day) gives caching the time it needs to pay off.

Both changes take minutes to implement and start showing results immediately. If you've just upgraded to Gemma 4, this is the right moment to rethink how you structure your Antigravity workflow — not just which model you're using.

For more on getting started with Gemma 4 in Antigravity, check out How to Use Gemma 4 in Antigravity: A Complete Guide to Google's Latest AI Model. If you're ready to move into larger-scale agent architectures, AgentKit 2.0 Complete Guide — Building Next-Gen AI Agents in Antigravity is worth reading next.