docs: remove unstable_disableValidation recommendations (#94608)

### What?

Removes `unstable_disableValidation` recommendations from all 14
insight-kind error pages and the `generateViewport` API reference. The
key on `unstable_instant`'s object form is not going to ship as a
recommended public API.

### Why?

Each error page's **"Don't want this validation?"** block previously
listed three opt-out levels:

1. **One segment** — `export const unstable_instant = false`
2. ~~**Layout and its children** — `export const unstable_instant = {
unstable_disableValidation: true }`~~ ← dropped
3. **Entire app** — `experimental.instantInsights.validationLevel:
'manual-warning'`

Dropping the middle bullet aligns the docs with the public-API surface
we intend to keep.

### How?

- Removed the `Layout and its children` bullet across 14 `errors/*.mdx`
pages.
- Removed the now-broken `See [Don't want this validation?] for the
subtree-wide opt-out` reference in the in-body **Gotchas** sections.
- Updated the `generate-viewport.mdx` API reference to drop the same
dangling reference.
- Framework source (`unstable_disableValidation` parsing in
`app-segment-config.ts` and runtime handling in `instant-config.tsx`) is
unchanged — that's a separate framework concern.

<!-- NEXT_JS_LLM_PR -->

errors/blocking-prerender-client-hook.mdx

@@ -271,7 +271,7 @@ Navigations to this route are not instant. The user waits for the full server re
 
 ### Gotchas
 
-- Setting [`instant`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to `false` opts only the segment that exports it out. Descendant segments are still validated by the global default. See [Don't want this validation?](#dont-want-this-validation) for the subtree-wide opt-out.
+- Setting [`instant`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to `false` opts only the segment that exports it out. Descendant segments are still validated by the global default.
 - This export does not disable [prerendering](/docs/app/glossary#prerendering). The route still prerenders if it can. It only silences the instant-navigation validation error.
 
 ## Don't want this validation?
@@ -279,7 +279,6 @@ Navigations to this route are not instant. The user waits for the full server re
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-crypto-client.mdx

@@ -181,7 +181,6 @@ The user sees the placeholder briefly before the real value. For interactions th
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-crypto.mdx

@@ -217,7 +217,6 @@ The first paint shows the SSR fallback (often `null`), and the value appears onl
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-current-time-client.mdx

@@ -225,7 +225,6 @@ Learn more: [`Date.now()` during prerendering](/docs/messages/blocking-prerender
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-current-time.mdx

@@ -275,7 +275,6 @@ Learn more: [`performance.now()`](https://developer.mozilla.org/en-US/docs/Web/A
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-dynamic.mdx

@@ -297,7 +297,7 @@ Navigations to this route are not instant. The user waits for the full server re
 
 ### Gotchas
 
-- Setting [`instant`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to `false` opts only the segment that exports it out. Descendant segments are still validated by the global default. See [Don't want this validation?](#dont-want-this-validation) for the subtree-wide opt-out.
+- Setting [`instant`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to `false` opts only the segment that exports it out. Descendant segments are still validated by the global default.
 - This export does not disable [prerendering](/docs/app/glossary#prerendering). The route still prerenders if it can. It only silences the instant-navigation validation error.
 
 ## Don't want this validation?
@@ -305,7 +305,6 @@ Navigations to this route are not instant. The user waits for the full server re
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-metadata-dynamic.mdx

@@ -156,7 +156,6 @@ The metadata and the dynamic marker run on every request, so the route cannot be
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-metadata-runtime.mdx

@@ -147,7 +147,6 @@ The metadata and the dynamic marker run on every request, so the route cannot be
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-random-client.mdx

@@ -174,7 +174,6 @@ The user sees the placeholder briefly before the real value. For interactions th
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-random.mdx

@@ -195,7 +195,6 @@ The first paint shows the SSR fallback or initial state, and the random value ap
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-runtime.mdx

@@ -283,7 +283,7 @@ Navigations to this route are not instant. The user waits for the full server re
 
 ### Gotchas
 
-- Setting [`instant`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to `false` opts only the segment that exports it out. Descendant segments are still validated by the global default. See [Don't want this validation?](#dont-want-this-validation) for the subtree-wide opt-out.
+- Setting [`instant`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to `false` opts only the segment that exports it out. Descendant segments are still validated by the global default.
 - This export does not disable [prerendering](/docs/app/glossary#prerendering). The route still prerenders if it can. It only silences the instant-navigation validation error.
 
 ## Don't want this validation?
@@ -291,7 +291,6 @@ Navigations to this route are not instant. The user waits for the full server re
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-viewport-dynamic.mdx

@@ -112,7 +112,7 @@ Navigations to this route are not instant. The user waits for the full server re
 
 ### Gotchas
 
-- Setting [`instant`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to `false` opts only the segment that exports it out. Descendant segments are still validated by the global default. See [Don't want this validation?](#dont-want-this-validation) for the subtree-wide opt-out.
+- Setting [`instant`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to `false` opts only the segment that exports it out. Descendant segments are still validated by the global default.
 - This export does not disable [prerendering](/docs/app/glossary#prerendering). The route still prerenders if it can. It only silences the instant-navigation validation error.
 - Framework-synthesized routes (`/_not-found`, `/_global-error`) inherit the root layout's `generateViewport` and must be statically prerendered. [`instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) silences the validation error but does not let those routes through, so the build still fails when they prerender. If your root layout's `generateViewport` depends on request data, [Cache the viewport data](#cache-the-viewport-data) instead, or move to [`global-not-found.js`](/docs/app/api-reference/file-conventions/not-found#global-not-foundjs-experimental), which bypasses the root layout entirely and avoids inheriting its `generateViewport`.
 
@@ -121,7 +121,6 @@ Navigations to this route are not instant. The user waits for the full server re
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/blocking-prerender-viewport-runtime.mdx

@@ -112,7 +112,7 @@ Navigations to this route are not instant. The user waits for the full server re
 
 ### Gotchas
 
-- Setting [`instant`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to `false` opts only the segment that exports it out. Descendant segments are still validated by the global default. See [Don't want this validation?](#dont-want-this-validation) for the subtree-wide opt-out.
+- Setting [`instant`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to `false` opts only the segment that exports it out. Descendant segments are still validated by the global default.
 - This export does not disable [prerendering](/docs/app/glossary#prerendering). The route still prerenders if it can. It only silences the instant-navigation validation error.
 - If the dynamic viewport is the only reason the route blocks, consider whether a static default covers most users. A static `themeColor` with a client-side correction after hydration may give a better experience than blocking the entire navigation.
 - Framework-synthesized routes (`/_not-found`, `/_global-error`) inherit the root layout's `generateViewport` and must be statically prerendered. [`instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) silences the validation error but does not let those routes through, so the build still fails when they prerender. If your root layout's `generateViewport` depends on request data, [Use static viewport](#use-static-viewport) instead, or move to [`global-not-found.js`](/docs/app/api-reference/file-conventions/not-found#global-not-foundjs-experimental), which bypasses the root layout entirely and avoids inheriting its `generateViewport`.
@@ -122,7 +122,6 @@ Navigations to this route are not instant. The user waits for the full server re
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.

errors/instant-unrendered-segment.mdx

@@ -139,7 +139,6 @@ The segment is exempt from instant-navigation validation. If it has issues that
 Instant-navigation validation runs by default in [Cache Components](/docs/app/api-reference/config/next-config-js/cacheComponents) apps and is what surfaces this error.
 
 - **One segment**: add [`export const instant = false`](/docs/app/api-reference/file-conventions/route-segment-config/instant) to the page or layout file. This opts out the segment itself. Child segments are still validated during client navigations.
-- **Layout and its children**: add `export const instant = { unstable_disableValidation: true }` to a layout. This disables validation for that layout and every segment below it.
 - **Entire app**: set [`experimental.instantInsights.validationLevel`](/docs/app/api-reference/file-conventions/route-segment-config/instant#configuring-validation-defaults) to `'manual-warning'` in `next.config`. This limits validation to segments that explicitly export `instant`.
 
 See [Ensuring instant navigations](/docs/app/guides/instant-navigation) for the full model.