Add ADR048: Immutable Form Versioning#248
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lfdebrux
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Mar 25, 2026
lfdebrux
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Mar 25, 2026
lfdebrux
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Mar 25, 2026
Outlines the transition from a mutable document-based system to an immutable versioning model for published forms. This includes new API endpoints for draft and versioned forms, addressing limitations in the current system and enhancing caching, submission tracking, and user experience during form completion.
Added a section on hard submission deadlines to ADR048, outlining the need for strict cutoff times for certain forms. This change clarifies that archiving will no longer serve as a method to prevent future submissions and suggests a new implementation approach for managing submission deadlines.
Added a section detailing how each submission will now store the `form_version` it was made against, helping proccess handle changes to the form.
Added a section detailing schema changes
lfdebrux
reviewed
May 12, 2026
Clarified language regarding mutable endpoints and the explicit linking of submissions to form versions. Updated sections on hard submission deadlines and the implications of archiving, ensuring consistency in terminology and enhancing clarity for future implementation considerations.
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If we ever wanted to allow rolling back to an older form version. The "live" form, may point to an older version not the "latest".
Realise we need to be able to find the archived version of the form to continue supporting the preview-archived form state.
Renamed the draft endpoint to `/api/v3/forms/:form_id/versions/draft` to make it more consistent that everything under /versions returns a form document.
Document how immutable form versions make Save and Return easier to implement and remove the need to store a form document on each submission.
stephencdaly
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May 20, 2026
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This ADR proposes changing GOV.UK Forms so each published form becomes a permanent, numbered version.
The main point is: once a form is published, that exact version will never change. If the form owner edits and republishes it, the system creates version 2, then 3, and so on. Users who started version 1 can continue with version 1, while new users get the latest live version.
Key benefits:
Better user journeys: people filling in a form are not disrupted if the form is changed or archived mid-way.
Support for future form versioning in Forms admin: form creators could see, manage, and understand the history of published versions.
Support future implementation of Save and Return: users could return to the same version of the form they originally started.
Clearer submission history: every submission records which form version it used.
Better downstream processing: processors no longer need to guess which form version (and it's structure) a submission relates to.
Improved performance, reliability and resilience to traffic spikes: published versions can be cached because they never change. If Forms Admin breaks, it's less likely to affect forms runner.
Stronger audit trail: the full history of published form versions is preserved.
The main product tradeoff is around archiving. Today, archiving can effectively stop people from submitting or progressing with the form. With immutable versions, archiving would stop new users from starting, but users already on a version may still be able to finish. For forms with strict legal or policy deadlines, we would need to re-implement that functionality explicitly.