Document session: false opt-out and session runtime tree-shaking

[adamchal]

Accompanies withastro/astro#16871.

Description (required)

Documents withastro/astro#16871, which adds a session: false config option to opt out of session support entirely, and tree-shakes the session runtime (AstroSession + unstorage) out of the SSR bundle for any project where no session driver is wired.

Changes (English only):

• guides/sessions.mdx: new "Disabling sessions" section (<Since v="7.1.0" />) covering the session: false option, that adapters skip wiring their default driver, that Astro.session/context.session are undefined (same as a project without sessions configured, so Astro.session?.get() feature detection keeps working), and a note that the runtime is tree-shaken automatically for any driver-less project even without the flag.
• reference/api-reference.mdx: session type corrected to AstroSession | undefined, and the disabled case added to the list of situations where session is undefined.
• guides/integrations-guide/cloudflare.mdx: note in the Sessions section that session: false means no KV binding is configured, no KV namespace is provisioned on deploy, and the session runtime is excluded from the Worker bundle.
• guides/integrations-guide/netlify.mdx: note that session: false means Netlify Blobs is not configured for session storage and the runtime is excluded from the function bundle.
• guides/integrations-guide/node.mdx: note that session: false means the filesystem driver is not configured and the runtime is excluded from the server bundle.
• reference/modules/astro-fetch.mdx: note on the sessions() pipeline handler that it registers no provider (and ctx.session is undefined) when no driver is configured or sessions are disabled.

References

• Related to feat(session): add session: false to opt out of session support astro#16871
• For Astro version 7.1.0 (and @astrojs/cloudflare 14.2.0, @astrojs/netlify 8.2.0, @astrojs/node 11.1.0)

Discord username: adam.chal

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Tracked Files

File	Note
en/guides/integrations-guide/cloudflare.mdx	Source changed, localizations will be marked as outdated.
en/guides/integrations-guide/netlify.mdx	Source changed, localizations will be marked as outdated.
en/guides/integrations-guide/node.mdx	Source changed, localizations will be marked as outdated.
en/guides/sessions.mdx	Source changed, localizations will be marked as outdated.
en/reference/api-reference.mdx	Source changed, localizations will be marked as outdated.
en/reference/modules/astro-fetch.mdx	Source changed, localizations will be marked as outdated.

Warnings reference

Icon	Description
🔄️	The source for this localization has been updated since the creation of this pull request, make sure all changes in the source have been applied.

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Preview deployment

✅ Deployment complete!

• Latest commit: 87eec16
• Preview: https://docs-session-false.previews.docs.astro.build
• Workflow run: View logs

[adamchal]

This may not make the Astro 7.1 release, so this will need to be updated accordingly.

[adamchal]

Suggested change

	## Disabling sessions
	### Disabling sessions

I think this might be better served as an <h3> so it sits under “Configuring sessions” instead of top level.

Before

• Overview
• Configuring sessions
  • Overriding the configuration at runtime
• Disabling sessions
• Interacting with session data
  • Astro components and pages
  • API endpoints
  • Actions
  • Middleware
• Session data types

After

• Overview
• Configuring sessions
  • Overriding the configuration at runtime
  • Disabling sessions
• Interacting with session data
  • Astro components and pages
  • API endpoints
  • Actions
  • Middleware
• Session data types