Back Shows the Old Region Through a Proxy? Test bfcache Restoration Separately

You inspect an owned regional catalogue through a proxy, open a detail page, and press Back. The old catalogue returns immediately, possibly without a new document request. That observation does not by itself show the proxy selected the wrong region. The browser may have restored a previous page from its back/forward cache, or bfcache.

Accept this journey by distinguishing restored state from newly fetched state. This guide proposes a small authorized staging test, not measured browser performance or a guarantee about 98IP. A fast return can be correct; a stale or incorrectly labeled result can still be a defect.

1. Define the return contract before measuring freshness

Choose an owned catalogue with a synthetic region marker, two known item IDs and a harmless data revision marker. Agree whether Back should preserve the user's selected region and filters, refresh selected fields, or ask before changing context. Network-derived region and a manual region selection are distinct inputs; write down which takes precedence.

Separate stable state from time-sensitive state. Keeping a scroll position can be desirable, while showing an expired availability claim may require revalidation. Define the permitted stale interval and the expected loading, error or confirmation state. Do not invent a freshness threshold after observing one run.

2. Know which kind of return you are testing

bfcache can restore an entire page, including its JavaScript state, from memory. It differs from the HTTP response cache and from a service worker returning a cached response. A restored page need not make a new document request, though the application may subsequently request data.

Use a real cross-document navigation from catalogue A to owned detail page B, then the browser Back action. A single-page application's internal route change is a separate case, not proof of a bfcache restoration. Do not replace Back with Reload and call the two journeys equivalent.

On your owned build, record the pageshow event and its persisted value. A true persisted value identifies a bfcache restore. pagehide.persisted can indicate an intention to cache, but does not guarantee a later restoration. If no restoration occurs, report that run as the non-restored branch rather than claiming bfcache coverage.

3. Establish an unchanged-route baseline

1. Record browser/OS versions, application build, route alias, account region, manual selection, storage state and fixture revision. Keep normal security settings.
2. Load catalogue A and record visible region, item IDs, revision, filters and scroll state. Preserve the small relevant network log.
3. Navigate to B, then use Back. Record pageshow.persisted, whether a document request occurred, follow-up data requests and the immediate visible state.
4. After the agreed settling condition, record the same fields again. Immediate and settled results are separate observations.
5. Repeat with the same fixture on a baseline route and an approved proxy route in equivalent contexts. Do not use elapsed time alone to identify the cache path.

The 98IP dynamic residential IP product page is relevant when testing region-sensitive requests through a chosen route. Confirm available targeting options in the actual account. A proxy cannot force a browser to discard a memory snapshot or make a new document request. Check documented connection setup through the API configuration page.

4. Change one controlled input while A is away

First keep the route unchanged and advance only the owned fixture's data revision while the user is on B. Go Back and compare behavior to the agreed freshness contract. A restored old revision is an observation; whether it fails depends on the promised revalidation behavior and deadline.

In a separate case, change the approved test route while A is away, using the client's documented lifecycle. Confirm that the change affects a new authorized probe before interpreting later requests; existing connections may not follow a newly selected configuration. Preserve A's page instance when possible. If changing the setup restarts the browser, it is not the same restoration experiment and must be labeled separately.

Do not assume an IP change must replace a deliberate manual region choice. If the contract preserves the user's selection, an old region marker can be correct. If the app promises current network defaults on return, verify that its actual revalidation request uses the intended route and that the settled marker matches its documented decision.

5. Inspect restoration and revalidation as separate stages

Build a ledger containing case ID, original page instance, initial revision, route before and after, pageshow.persisted, document request, data request, immediate state, settled state and expected rule. Keep fixture IDs rather than customer records or raw personal location data.

If persisted is true and no new request occurs, investigate the restore contract before blaming the proxy. If a data request returns the new revision but the page still renders the old one, inspect application state and stale callbacks. If the request itself uses the earlier route, investigate the client's connection lifecycle separately. If persisted is false, investigate the reload path without merging it into restored-page results.

A revalidation failure also needs a visible product outcome. The app might retain an explicitly marked earlier snapshot or require a retry; choose that policy beforehand. An unmarked stale view that appears newly verified should not pass merely because the old catalogue looks plausible.

6. Exercise the detector on an owned staging build

Propose three local fault cases: suppress the app's intended return-time revalidation, return a new revision but leave the old DOM visible, and deliver a delayed old response after a newer result. Confirm that the report identifies the failing stage and that the app prevents the delayed result from overwriting current state. These exercises have not been executed as part of this guide.

Run a non-restored return as a comparison, using a documented test setup and labeling the actual observed branch. Do not disable browser optimizations globally just to make a freshness test pass, or remove production privacy protections to force caching. A branch that cannot be exercised in the available browser remains untested.

FAQ and acceptance checklist

Is no document request evidence of a proxy failure? No. Combine lifecycle evidence, application requests and the expected return policy. A memory restoration is not a new fetch through the selected proxy.

Does manually refreshing after Back prove the journey is correct? No. Refresh can demonstrate a different path works while hiding a restoration defect.

• Manual region, network default and freshness rules are defined independently.
• Cross-document Back and application soft navigation are labeled separately.
• The actual persisted branch is recorded rather than inferred from speed.
• Immediate state, revalidation result and settled UI have separate evidence.
• Route changes are verified on new requests without silently restarting the test.
• Unsupported or unexercised branches remain explicitly untested.

Use only owned or expressly authorized pages, synthetic revisions and a small request budget. Redact credentials and signed links, limit evidence retention and identify the tested browser matrix. Do not infer universal cache behavior, location accuracy, bandwidth savings or business results from these proposed checks.