Learn
It starts with your code.
Connect your repository. Sustain reads how your app is built, including its dependencies and release pipeline, so checks have the right context.
Watch uses read-only access.Put your app's maintenance on autopilot.
Sustain is an AI agent that watches your app, fixes routine issues before they break anything, and keeps it current as the APIs it calls and the app stores change. You decide how much it can ship.
Sustain supports Flutter and Firebase apps at launch, and the live demo connects yours read-only.
What Sustain watches, on a schedule
- API changes
- Uptime
- Error rates
- Certificates
- API keys
- Dependencies
- Security alerts
- Store deadlines
- Billing health
Software starts decaying the day it ships.
The code can sit untouched for a year. The platforms, packages and services around it keep changing anyway, until something breaks.
A year without maintenance
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Launch
Everything works
The app ships. The code stays exactly how the developer left it.
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Month 2
A package is deprecated
Something the app is built on stops getting updates.
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Month 4
The cloud bill creeps up
Costs rise a little every month, and nobody is watching them.
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Month 7
Security patches pile up
Fixes for known vulnerabilities sit unapplied.
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Month 9
A certificate expires
Users start seeing errors. The person who knew the renewal date has moved on.
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Month 12
The store rejects your update
Apple or Google raised the SDK requirement. Your next release can't ship until someone updates the app.
Most owners hear about these from their users. Sustain checks for them on a schedule, before your users do.
The APIs your app calls keep changing.
Code nobody touched still breaks when a vendor moves on: Stripe ships a new SDK major, a model you call is retired, Firebase stops deploying an old Node version. Sustain reads each vendor's own changelog every day, finds where a change reaches your code, and shows the date it stops working, when the vendor has set one.
- Source
- The vendor's own release notes and deprecation pages. A person reviews each change before it becomes a rule.
- Reach
- Your code and your connected accounts, so Sustain sees the API version your Stripe webhooks use as well as the one your code asks for.
- Fix
- A tested pull request on Maintain and Autopilot, for the kinds of change Sustain has proven it can fix.
- Vendors
- Stripe, Firebase, Supabase, RevenueCat, OpenAI and Anthropic
-
AnthropicAnnounced 30 Sep 2026
claude-sonnet-4-5-20250929 retires on 30 Nov 2026
In your code
server/src/tags.js:18Move to
claude-sonnet-5-5 -
FirebaseSince 30 Oct 2025
Cloud Functions stops deploying Node.js 18
In your code
functions/package.jsonDeploys fail
-
StripePublished 30 Sep 2026
stripe-node 23 pins API 2026-09-30.endive
In your code
functions/ on stripe 11Webhooks on API
2024-06-20
Fix prepared for functions/: Node.js 22, tests passed. Waiting for your approval.
Follow a fix
through Sustain.
It learns your app, watches it, fixes it, and ships only what you allow. Explore the connections, then run an example.
Example: a dependency needs updating
Choose a plan, then run the example.
Watch
It watches the services your app relies on.
Scheduled checks cover uptime, errors, certificates, API keys and billing health. Sustain tells you what needs attention and why.
Billing monitoring never moves your money.Watch
Platform changes become work you can plan.
Sustain checks app store and platform requirements against your app's profile, so you can deal with SDK deadlines and dependency changes before they block an update.
Flutter and Firebase apps at launch.
Learn
A working understanding of your app.
Your code and connected accounts become a project profile that describes how everything fits together. Read it, correct it, and add the context only you know.
It can teach you, too. Turn on Teach me, and each finding comes with a lesson like this one, with an example from your own code.
Learning updates this editable profile, not model weights.What this teachesSUS-0017
WillPopScope breaks Android's predictive back
- Why it's a risk
- Predictive back changed how Android decides whether a screen can close. WillPopScope can't take part in that, so its check comes too late or not at all.
- How to spot it
- Search for WillPopScope; the analyzer also reports it as deprecated.
- How to avoid it next time
- Use PopScope with canPop for any screen that guards unsaved work, and test the back gesture, not only the back button.
From your code: lib/src/notes/note_screen.dart, line 69
return WillPopScope( onWillPop: _confirmDiscard, child: Scaffold(This uses WillPopScope to guard back navigation, which is the pattern that breaks Android predictive back. The discard check can run too late, so this screen should use PopScope with canPop instead.
Saved to your lessons. On Autopilot, saved lessons export to AGENTS.md, CLAUDE.md or Cursor rules.
Watch
Every finding has a reason.
A rulebook that people review turns service signals and platform requirements into checks for your app. Each finding points back to the rule that raised it.
On Watch, every issue includes a brief for your developer.Watch
Checks that know your app.
Sustain runs its rulebook against your app's profile on a schedule. It reports what needs work and, on Maintain and Autopilot, prepares the routine fixes.
If it cannot fix an issue safely, it writes a handoff brief.Fix
A tested change before a live one.
Dependency, SDK and security fixes go onto a branch, through tests and staging, then into a pull request. Each one explains itself in two lines.
Available on Maintain and Autopilot. Watch never changes code.Ship
You set the boundary.
On Maintain, you approve or decline every fix. On Autopilot, a fix can merge only when its type has proven itself on your app, the checks pass, and your rules allow it.
Try the approval and rollback controls in the example.Ship
The work continues after the fix.
Your own pipeline handles deployment after a merge, and Sustain keeps watching for regressions. Watch ends with a report and a brief, without changing the app.
Autopilot can apply safety brakes when a release goes bad.The upkeep that keeps getting put off.
Some of it comes with every plan. The fixes start on Maintain.
Maintain and Autopilot
Fixes arrive as pull requests.
Dependency, SDK and security fixes, tested and run through staging before they merge. This one is the first fix Sustain verified, made for our own test app when OpenAI's Node SDK moved to version 4.
- Rule
- SUS-0081
- Vendor change
- openai-node 4.0.0
- Changed
- 3 files, +113 −49
- CI
- passed in 24 s
Move to the OpenAI v4 SDK
#1 · sustain-rot-lab
Checks passed
functions/src/index.ts+4 −4
@@ -1,13 +1,13 @@
import { Configuration, OpenAIApi } from 'openai'
import OpenAI from 'openai'
…
const openai = new OpenAIApi(new Configuration({ apiKey: process.env.OPENAI_API_KEY }))
const openai = new OpenAI()
@@ -29,12 +29,12 @@ export const summarizeNote
const completion = await openai.createCompletion({
const completion = await openai.completions.create({
…
const summary = trimSummary(completion.data.choices[0]?.text ?? '')
const summary = trimSummary(completion.choices[0]?.text ?? '')
functions/package.json+1 −1
- Build,
npm run buildpassed - Lint,
npm run lintpassed - Tests,
npm run testpassed - Types,
tsc --noEmitpassed - GitHub Actions, Functionspassed in 24 s
Watch tracks it. Maintain and Autopilot prepare the update.
App store deadlines, weeks ahead.
Apple and Google change their rules every year. Sustain tracks the deadlines that affect your app. On Maintain and Autopilot, it prepares the update well before the cutoff.
Maintain and Autopilot
Rolling back is a pull request too.
Undo a fix with one tap, and Sustain opens a revert pull request that goes through the same checks the fix did. On Autopilot, it reverts a fix that causes a regression without waiting for you.
Illustrative. The deadline and rollback screens are examples.
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Every plan
You can read what it knows about your app.
The agent writes down how your app is built, in a profile. If something in it is wrong, correct it. When your edit and Sustain's reading disagree, yours wins.
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Every plan
Reports you can read without a developer.
Each report says what Sustain checked, what it found and what it's doing about it.
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Every plan
A brief your developer can pick up.
It explains the problem in everyday words for you and adds the technical notes a developer needs. On Watch you get one for every issue; on Maintain and Autopilot, for anything too risky to change automatically.
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Agency plan
Maintenance under your own name.
Agencies and freelancers can offer app maintenance under their own brand. Clients see you, and Sustain does the work in the background.
The limits Sustain works within.
Sustain gets access to your app, so its limits are written down: what it does on its own, what it asks you first, and what it never does.
Does on its own
- Runs checks on a schedule
- Writes reports and briefs
- Prepares and tests fixes in staging, on Maintain and Autopilot
- On Autopilot, merges fix types that have proven themselves on your app, and reverts one if anything regresses
- On Autopilot, stops a bad release: it halts store rollouts and switches off risky changes
Asks you first
- On Maintain, every fix before it merges
- On Autopilot, any fix type that hasn't proven itself on your app yet
- Anything too risky to change automatically, which it hands you as a brief
- Every change it asks about comes with a two-line explanation
Never does
- Deploys to your live app by itself
- Moves money
- Changes anything on Watch, where access is read-only
- Watch access
- Read-only
- Rollback
- On every fix
- Models
- Anthropic and OpenAI, chosen per task
- Launch stack
- Flutter and Firebase
Security and dataWhat Sustain can accessData processingPrivacyTermsSystem status
Choose how much the agent does.
Each plan includes everything in the one before it. Prices open at launch.
Watch
For your developer
Autonomy1 of 3
For apps that already have a developer. It watches the app and tells them what to fix.
Early accessPrices open at launch
Join early access
What's included
- Uptime checks every 15 minutes
- Crash and error monitoring
- Keys, certificates and billing health
- Store and platform deadlines, weeks ahead
- A brief for every issue, ready for your developer
- A project profile you can read and edit
- A monthly report in plain English
Maintain
You approve changes
Autonomy2 of 3
For owners who want every change in front of them. It does the fixing, and nothing ships until you approve it.
Early accessPrices open at launch
Join early access
What's included
- Everything in Watch
- Dependency, SDK and security fixes
- Tested pull requests, run through staging
- You approve every change
- One-tap rollback
- UI consistency passes on request
- Uptime checks every 5 minutes
Autopilot
Proven fixes merge on their own
Autonomy3 of 3
For apps nobody's watching. It merges the fixes it has proven on your app, keeps dependencies current, and stops a bad release on its own.
Early accessPrices open at launch
Join early access
What's included
- Everything in Maintain
- Ships proven fixes on its own
- Keeps everything current in small steps
- Writes the tests your app is missing
- Safety brakes when a release goes bad
- Uptime checks every minute, full scans hourly
- A weekly digest of everything it did
Add-on for any plan
Risk and policy checks
Flags store policy, privacy disclosure and accessibility issues. It doesn't guarantee compliance.
For agencies
Agency plan
Priced per app, with white-label so the service runs under your own brand.
Compare every plan
| Watch | Maintain | Autopilot | |
|---|---|---|---|
| Best for | Apps with a developer | Owners who want sign-off | Apps nobody's watching |
| Access to your app | Read-only | Pull requests | Pull requests, auto-merge, safety brakes |
| Uptime checks | Every 15 min | Every 5 min | Every minute |
| Full health scan | Daily | Daily | Hourly |
| Crash and error monitoring | |||
| Keys, certificates and billing health | |||
| Store and platform deadlines | Early warning | Fixed, you approve | Fixed on its own |
| Editable project profile | |||
| Briefs your developer can act on | Every issue | When it can't fix | When it can't fix |
| Plain-English report | Monthly | Monthly | Weekly |
| Dependency, SDK and security fixes | |||
| Staging tests before merge | |||
| Who approves fixes | You, every time | You, until each fix type proves itself | |
| One-tap rollback | |||
| UI consistency passes | On request | On request | |
| Keeps everything current | |||
| Writes missing tests | |||
| Safety brakes on bad releases | |||
| Risk and policy checks | Add-on | Add-on | Add-on |
Join the first pilots.
Pilots haven't started yet. At launch Sustain supports apps built with Flutter and Firebase.
It's built for agencies and freelancers who maintain client apps, and for owners of custom apps who have no developer on hand. When pilots open, we write to the address you give.
See the demo and results so far
Sustain grew out of the custom apps Zetesis builds for its clients. If you want to talk it through before you sign up, write to me.
Yuvraj SharmaFounder, Zetesis
On the list
You're on the early access list.
Updates go to the address you gave.
To change anything, email yuvi@zetesis.dev.