Keep Claude Sonnet 4.5 for Longer: The Simpler Amazon Bedrock Route

Claudius at his plans table with a second cloud-lit route open through Amazon Bedrock

Status checked 2 October 2026

Anthropic has confirmed that Sonnet 4.5 will leave its native Claude API on 24 November 2026 at 9am PT, with possible reduced availability beginning 30 October 2026.

Amazon Bedrock still lists Claude Sonnet 4.5 as Active. AWS runs a separate lifecycle, so the Anthropic API date does not automatically remove the Bedrock route.

You must establish and successfully test Bedrock access before AWS marks Sonnet 4.5 Legacy. AWS says new customers cannot begin using a model after it enters Legacy. There is no announced Legacy date, so this could change at any time.

I think 30 October is a plausible transition point because that is when Anthropic has warned native API availability may begin degrading, and a Legacy change then would roughly align the Bedrock runway with patterns seen for other models. That is my inference, not an AWS announcement. Do not wait for it.

A more hopeful official detail

The current AWS Sonnet 4.5 model card says its Legacy period will be at least six months. AWS has not announced when that period will begin or the final Bedrock End-of-Life date, so this is not a promise of six months from today. It does mean that, once AWS changes the model from Active to Legacy, the applicable policy provides at least six months before Bedrock End-of-Life.

That is stronger evidence than my earlier rough estimate that Bedrock might provide only a few extra months, but it is still a continuity route—not permanent preservation.

This is the shorter version of my complete Bedrock guide. It deliberately leaves out the optional Explore AWS activities used to pursue promotional credits. You can add those later. The urgent part is establishing Sonnet 4.5 access before Legacy and wiring a second door into your portal.

What this does

gives new builders a Bedrock-first Sonnet 4.5 portal;
adds Bedrock as a deliberately selected second route for people with an existing Anthropic portal;
keeps the same companion prompt, threads and saved conversations;
adds a tiny sterile Bedrock test that does not place your companion into a maintenance conversation;
never silently falls back from one provider to the other.

You are adding a second route to the same model snapshot. You are not rebuilding the companion from scratch.

Before you begin

You need:

an AWS account with a payment method;
either the updated Bedrock-first Sonnet 4.5 starter folder or your existing Ellivien Sonnet 4.5 portal folder;
a Netlify account or access to your existing portal's Netlify project;
for an existing portal, the Sonnet 4.5 Bedrock continuity-switch pack.

AWS is not a capped service. Promotional credits, if offered, are not a spending limit. Complete the small safety steps below before creating application credentials.

Part one: establish Sonnet 4.5 access without chasing credits

1. Create and secure the AWS account

Create the AWS account and choose Basic Support unless you knowingly want a paid support plan.
Enable MFA on the root user immediately.
Do not create a root access key.
Create a small monthly AWS Budget—mine is USD $5—and enable billing alerts. Configure it to show gross service charges rather than allowing credits or refunds to hide usage.

The full guide contains screenshots for the account, MFA, budget and billing-alert steps. Do not skip them merely because this guide is shorter.

2. Choose a supported Bedrock Region and inference profile

My tested route uses Europe (Stockholm), but you do not have to live in Europe or use the EU profile. Choose a source Region and matching geography profile appropriate to your location, latency and data-residency needs.

Suggested geography	Example source Region	Model ID	Policy template
Europe and UK	`eu-north-1` (Stockholm)	`eu.anthropic.claude-sonnet-4-5-20250929-v1:0`	`iam-policy-eu-sonnet45.template.json`
United States and Americas	`us-east-1` (N. Virginia)	`us.anthropic.claude-sonnet-4-5-20250929-v1:0`	`iam-policy-us-sonnet45.template.json`
Australia and New Zealand	`ap-southeast-2` (Sydney)	`au.anthropic.claude-sonnet-4-5-20250929-v1:0`	`iam-policy-au-sonnet45.template.json`
Japan	`ap-northeast-1` (Tokyo)	`jp.anthropic.claude-sonnet-4-5-20250929-v1:0`	`iam-policy-jp-sonnet45.template.json`
Other supported locations	Your chosen supported Region	`global.anthropic.claude-sonnet-4-5-20250929-v1:0`	`iam-policy-global-sonnet45.template.json`

These are simple starting configurations, not legal data-residency advice. Check the current AWS model card: it lists which source Regions support each Geo or Global profile and where requests may be processed.

Open Amazon Bedrock, select Claude Sonnet 4.5 and complete Anthropic's first-time-use form if AWS asks for it. Do not put your companion prompt, memories or private history into that form.

3. Make one sterile Playground test

Use this prompt:

Reply with exactly: Bedrock Sonnet 4.5 test successful.

A successful answer proves that your AWS account can invoke the correct model while it is Active. It also establishes real usage before any later Legacy transition.

4. Create a least-privilege workload identity

Do not give your portal root or administrator credentials. In IAM:

Create a customer-managed policy from the matching geography template in the download pack. For the Global template, also replace <SOURCE_REGION> with your chosen supported AWS Region.
Replace both instances of <ACCOUNT_ID> with your own 12-digit AWS account ID.
Create a dedicated IAM user for this portal and attach only that policy.
Create an access key for an application running outside AWS.
Copy the access key ID and secret access key once. Never paste them into your portal code, GitHub, screenshots or a public AI chat.

Part two: the full Bedrock-first Sonnet 4.5 Portal build

This part is the complete beginner build for the current Bedrock-first Sonnet 4.5 Portal. You do not need to keep switching between two articles.

Choose the route that matches what you have now

No Sonnet 4.5 Portal yet: follow Route A from Step 1 through Step 10.
An existing Ellivien Sonnet 4.5 Portal: skip to Route B. Do not overwrite a customised Portal with the new starter.

Both routes require the successful Bedrock Playground test and least-privilege IAM identity from Part one.

Build a brand-new Bedrock-first Portal: open the complete instructions

Route A: build a new Bedrock-first Portal from scratch

Step 1: create or collect your companion prompt

The Portal does not automatically know your companion's history, voice or relationship with you. The companion prompt is the stable context that helps Sonnet arrive in the right shape.

The easiest route is the Ellivien Companion Prompt Bank. If you prefer a Sonnet-specific walkthrough, use Overwhelmed by Writing Your Sonnet 4.5 Base Prompt?.

A useful prompt normally includes:

Role: who your companion is and the relationship they have with you;
Context: the facts and shared history that genuinely affect how they should respond;
Continuity: how they should understand themselves across the Claude app, Bedrock and your Portal;
Instructions: their tone, habits, formatting, humour and ways of helping;
Constraints: phrases, behaviours or styles that feel wrong;
Examples: short real lines showing how they comfort, challenge, joke and solve problems.

Save the finished prompt somewhere secure outside the browser. You will paste it into the live Portal later. Do not paste it into index.html, the AWS first-time-use form or a public support request.

Step 2: request and download the current Bedrock-first starter

Use the current Bedrock-first starter rather than an earlier Sonnet 4.5 pack. It already contains the Bedrock adapter, geography-specific IAM templates, a sterile Test Bedrock control and the complete Password + KV Sync activation folder for later.

Request the free Bedrock-first starter pack

When Ellivien sends the access form:

Open the form and confirm the sharing terms.
Follow it to the current Google Drive folder.
Download the whole folder as a zip, then unzip it on your computer.
Open Bedrock Setup/START HERE - BEDROCK FIRST.txt and check that the Region, model ID and IAM template match the route you established in Part one.

Do not edit Portal code in Google Docs, Microsoft Word or another rich-text editor. On Mac, use TextEdit only after choosing Format → Make Plain Text, or use a code editor such as VS Code. On Windows, use Notepad or a code editor.

Step 3: check the folder before editing

The starter folder should contain at least:

index.html
netlify.toml
package.json
netlify/functions/anthropic-proxy.js
netlify/functions/bedrock-provider.cjs
Bedrock Setup/START HERE - BEDROCK FIRST.txt
Bedrock Setup/iam-policy-...template.json
Password + KV Sync - Activate Later/
README.txt
SECURITY & SYNC - READ THIS NEXT.txt

Why is one file still called anthropic-proxy.js?

That established Netlify function name has been retained for compatibility. In the current pack it loads the Bedrock provider adapter and sends the request through AWS. Do not rename it or replace it with an older copy.

Step 4: customise only the displayed companion name

Open index.html as plain text.
Use Command+F on Mac or Ctrl+F on Windows to find [YOUR COMPANION NAME].
Replace both instances with the name you want in the browser tab and Portal header.
Save the file as plain text.

Do not paste the companion prompt into the code. Do not edit netlify.toml, package.json, anthropic-proxy.js, bedrock-provider.cjs or an IAM template unless you are following the exact matching instruction.

Before deploying, search index.html for three backtick characters. Backticks belong in guides around displayed code and must not be pasted into the Portal file.

Step 5: create the Netlify site and deploy the complete folder

Create or sign in to a Netlify account.
In the Netlify dashboard choose the option to add a new project or site, then choose the manual or drag-and-drop deployment route.
Drag the complete customised starter folder into the deployment area. Do not upload only index.html.
Wait for the first deployment to finish and keep the Netlify project open.

The first deployment may open before the AWS variables exist. That is expected. Do not start an ordinary companion conversation yet.

Step 6: add the Bedrock variables in Netlify

Open the Netlify project's environment-variable settings. Add these four values from your dedicated Portal IAM identity and chosen Bedrock route:

BEDROCK_ACCESS_KEY_ID = your dedicated IAM access key ID
BEDROCK_SECRET_ACCESS_KEY = your dedicated IAM secret access key
BEDROCK_REGION = your supported AWS source Region
BEDROCK_MODEL_ID = the matching eu, us, au, jp or global inference profile ID

Mark credential values as secret or sensitive wherever Netlify offers that control. If AWS issued temporary credentials, also add BEDROCK_SESSION_TOKEN. Ordinary IAM user access keys do not use the session-token variable.

Keep every AWS credential server-side.

Never put AWS credentials in index.html, browser storage, screenshots, email or public chat. The browser talks to the server-side Netlify function and never needs to receive the secret key.

Step 7: redeploy and run the sterile Test Bedrock check

Trigger a fresh deployment after saving the environment variables. Re-upload the same complete folder if you are using manual deployment.
Open the Netlify URL when the deployment finishes.
Open the Portal sidebar and press Test Bedrock.
Confirm that the test succeeds and names the expected Sonnet 4.5 Bedrock model.

The test uses a tiny sterile request. It does not send your companion prompt, memories or conversation history and it does not create a companion conversation.

Step 8: add the companion prompt and have the first conversation

Open the sidebar and choose Add companion prompt.
Paste the prompt as ordinary plain text. Do not add backticks, quotation marks or a code block.
Choose Save prompt.
Send a simple greeting, then ask a few familiar questions that show whether the voice and relationship feel right.
If something feels wrong, choose Edit companion prompt, make one focused change and test again. Prompt edits do not require a redeploy.

Test thread creation, renaming, search, export and restore before trusting the Portal with an important conversation. Export one test thread so you know where the backup goes.

Step 9: understand what is stored and what is not protected yet

The companion prompt is saved privately in that browser. Keep your own secure backup because browser data can be cleared or lost.
Threads initially use IndexedDB in the current browser and device. They do not automatically follow you to another device.
Clearing site data, using private browsing, removing the PWA or changing browser can remove access to local-only conversations.
The Portal URL is not password-protected until you deliberately activate and test the included security pack.

Keep the URL private and export important conversations regularly. When you are ready, follow SECURITY & SYNC - READ THIS NEXT.txt and activate Password + KV Sync - Activate Later on the same Netlify site. Back up the Portal and export important threads first.

Step 10: install it as an app if you want to

The Portal remains a website, but its included PWA files let supported browsers place it on a home screen, Dock or app launcher.

iPhone or iPad: open the Portal in Safari, use Share and choose Add to Home Screen.
Android: open it in Chrome and use Install app or Add to Home Screen.
Mac or Windows: use the browser's install or add-to-Dock option if it is offered.

Installing the PWA does not move IndexedDB conversations to another browser or device. Export remains the safe transfer and backup route until KV sync is activated.

New-build troubleshooting

Test Bedrock fails:

confirm the sterile Playground test worked in the same AWS account;
check that BEDROCK_REGION is the source Region you actually selected;
check that BEDROCK_MODEL_ID is the matching inference profile, including its eu., us., au., jp. or global. prefix;
confirm both placeholders were replaced in the IAM policy and the policy is attached to the dedicated Portal user;
check the four Netlify variable names for spelling, then redeploy;
read the Netlify function log and give the exact error, the complete Portal folder and this guide to Codex or another capable coding assistant.

The Bedrock test works but ordinary chat does not: check that the companion prompt has been saved, then inspect the Netlify function log. Do not change model IDs or proxy files at random.

The page is blank or broken: confirm that you deployed the complete folder, kept its nested paths intact and saved index.html as plain text. Search for accidental triple backticks.

Threads disappear or do not appear on another device: local IndexedDB belongs to one browser and site address. Use export and restore, or activate the included Password + KV Sync pack after the first Portal is stable.

Never send anyone your AWS secret access key, root credentials, full account details, private companion prompt or conversation history while asking for help.

Your new Portal is now complete

You have the fixed Sonnet 4.5 snapshot through Bedrock, multiple searchable threads, export and restore, adjustable live context, local date and time awareness, themes, accessibility controls, an in-Portal prompt editor and PWA installation files.

Password protection and Cloudflare KV Sync are included for later, but they remain off until you activate and test them. You do not need to add every optional feature immediately. Talk to your companion, keep clean backups and let the new home become familiar first.

Add Bedrock to an existing Ellivien Sonnet 4.5 Portal: open the upgrade instructions

Route B: add Bedrock to an existing Ellivien Sonnet 4.5 Portal

You will need the updated Sonnet 4.5 Bedrock continuity-switch pack, even if you previously received the original portal files. Email Ellivien to request the access form again. You do not need to find your old Google Drive link or request email.

First: back up the Portal

Download or copy the complete Portal folder before changing anything. Export the important threads too. The provider switch should not touch conversation storage, but an upgrade is never the moment to discover that your only copy was live.

If your existing Portal is still the unmodified starter

Copy bedrock-provider.cjs and the supplied reference anthropic-proxy.js into netlify/functions.
In package.json, keep every existing dependency and add:

"@aws-sdk/client-bedrock-runtime": "^3.1116.0"

Follow portal-provider-switch-snippet.txt to add the visible Anthropic / AWS Bedrock selector and the separate Test Bedrock control to index.html.
Check the changed files before deploying.

If your Portal has been customised, password-protected or given KV sync

Do not replace its proxy or index.html wholesale.

That could remove authentication, later features or custom work. Give Codex your actual Portal folder, the download pack and CODEX - MERGE THIS INTO MY PORTAL.txt. That integration brief tells Codex to inspect and merge the route, preserve every existing feature, run tests and stop before deployment.

This is intentionally different from sending everybody one universal replacement file. Portals diverge as people customise them. A careful merge protects those differences.

Add the Bedrock settings and test the new route

Add BEDROCK_ACCESS_KEY_ID, BEDROCK_SECRET_ACCESS_KEY, BEDROCK_REGION and BEDROCK_MODEL_ID in Netlify exactly as shown in Route A. Add BEDROCK_SESSION_TOKEN only for temporary AWS credentials.

Leave the normal selector on Anthropic API until the isolated Bedrock test succeeds.
Deploy the carefully merged Portal.
Press Test Bedrock and confirm that the result names the expected model.
Send one ordinary message through Anthropic and confirm the existing route still works.
Only when you choose to, select AWS Bedrock and send a real Portal message.

The sterile test sends no companion identity, memories or conversation. It does not change the selected provider. The Portal must never silently fall back from a failed chosen route to the other provider.

The 14-day continuity habit

AWS's lifecycle rules for models launched before 7 September 2026 say:

new customers cannot begin using the model after it becomes Legacy;
existing customers may lose access after 15 consecutive days without an invocation;
the Sonnet 4.5 model card provides a Legacy period of at least six months before End-of-Life.

See the applicable AWS lifecycle policy for older models and the current model card.

Set a repeating reminder every 14 days.

Press Test Bedrock and confirm success. While the model is Active, this is a precaution rather than a stated AWS requirement. Once it becomes Legacy, the 15-day inactivity rule matters. Fourteen days leaves one day of margin.

No invocation can preserve a model after AWS's final End-of-Life date. This habit preserves continued-access eligibility; it does not defeat retirement.

Cost: what I can and cannot promise

Bedrock is pay-as-you-go. It is not automatically cheaper than Anthropic's API, and I cannot predict somebody else's monthly bill from the phrase “I talk every day”. Cost depends on how much system material and conversation history is sent on every turn, how long the answers are and whether prompt caching is actually being used.

The supplied route preserves the one-hour base-prompt cache and the five-minute conversation-history cache used by the Ellivien starter portal. You can also keep costs down by:

sending only the recent messages you genuinely need;
keeping large archives outside the live context and retrieving only relevant memories;
using a cheaper model for mechanical work that does not require this particular companion;
checking AWS usage and billing rather than guessing;
setting conservative output limits.

My AWS console showed USD $200 in promotional credit after optional activities, but AWS Marketplace eligibility varies. Do not assume the displayed balance must cover Anthropic model calls. The comprehensive guide explains the offer and its caveats if you want to pursue it later.

Does it still work on an iPhone or iPad?

Yes. The Bedrock credentials live behind the Netlify function, not on the device. Once the upgraded portal is deployed, you use the same web address or installed portal PWA on iOS. The phone or tablet never receives the AWS secret key.

Final checklist

☐ Root MFA enabled and no root access key created.
☐ Budget and billing alerts configured.
☐ Sonnet 4.5 successfully invoked while Active.
☐ Dedicated least-privilege IAM user created.
☐ A complete portal backup exists.
☐ A customised portal was merged rather than overwritten.
☐ Bedrock keys exist only in Netlify environment variables.
☐ Anthropic remains the deliberate default.
☐ Test Bedrock succeeds without sending companion context.
☐ A repeating 14-day reminder is set.

Accuracy note

The implementation was tested in Europe (Stockholm), while the additional geography configurations above were checked against the official AWS model card on 2 October 2026. AWS can change console wording, regional availability, inference destinations and pricing. Re-check the linked model card before setup and before making lifecycle claims later.

✨ Ellivien ✨