poc: Full Observed Versions support

[thykel]

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Merge checklist

• Added/updated tests
• Added/updated documentation in Lookbook (patterns, previews, etc)
• Tested major browsers (Chrome, Firefox, Edge, ...)

[github-actions]

Warning

Flaky specs

• rspec ./spec/features/work_packages/table/queries/subject_filter_spec.rb[1:1]

🤖 Ask Copilot to investigate

Copy the prompt below into a new comment on this PR to delegate the investigation to GitHub Copilot. It will look into the flakiness and open a separate pull request with you as reviewer.

@copilot The following spec(s) are flaky in CI (first seen on PR #24606, linked for reference only):

- `rspec ./spec/features/work_packages/table/queries/subject_filter_spec.rb[1:1]`

Treat this as a standalone task, unrelated to PR #24606. Create a new branch from origin/dev and open a new pull request targeting dev — do not stack it on PR #24606 or reuse that branch.

Follow the playbook in docs/development/testing/handling-flaky-tests/README.md to find the root cause and fix the underlying race — do not skip, delete, or weaken the spec to make it pass; disabling is a last resort per the playbook, and only with a bug ticket. Verify the fix by running the spec(s) repeatedly (e.g. `script/bulk_run_rspec --run-count 10`).

If you cannot reproduce the flake or are not confident in a fix after reasonable investigation, do not fabricate a change or skip the spec to force CI green. Instead, leave the pull request in draft and document what you tried, the suspected cause, and any leads in its description, then assign @thykel to take over.

Once the fix is verified, title the PR after the spec(s) it fixes, and use the PR description to explain the root cause, how the change resolves it, and the before/after results. Label the PR `flaky-spec`, assign @thykel, and request a review from @thykel.
On every commit, set @thykel as the sole co-author with a `Co-authored-by:` trailer (use their GitHub no-reply email so it links to their account), so it is traceable who dispatched the fix.

[Copilot]

Pull request overview

This PR extends OpenProject’s multi-version infrastructure by adding end-to-end support for “Observed versions” (observedInVersions / observed_in_versions) across API v3 representations and schema, query filters/sorting, journaling, exports (PDF/XLS), and frontend editing.

Changes:

• Add observedInVersions as a first-class API v3 work package link collection (representer + schema + docs) and include it in cache checksum calculation.
• Add query support for observed versions (filter, select/sort/group SQL) and wire it into the WorkPackage query filter set.
• Journal and export observed versions, including a new shared journal formatter for joined version lists and additional eager loading for journal activities.

Reviewed changes

Copilot reviewed 36 out of 36 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
spec/models/work_packages/pdf_export/work_package_to_pdf_spec.rb	Updates PDF export expectations to include “Observed versions” in details output.
spec/lib/api/v3/work_packages/eager_loading/cache_checksum_integration_spec.rb	Adjusts checksum expectation so observed-in version changes bust the cache.
modules/xls_export/app/models/xls_export/work_package/exporter/xls.rb	Eager-loads observed_in_versions for XLS exports.
lib/open_project/journal_formatter/target_versions.rb	Refactors TargetVersions formatter to inherit from new JoinedVersions.
lib/open_project/journal_formatter/observed_in_versions.rb	Adds journal formatter for observed-in versions.
lib/open_project/journal_formatter/joined_versions.rb	Introduces shared formatter for rendering comma-joined version name lists from stored ID strings.
lib/api/v3/work_packages/work_package_representer.rb	Exposes observed_in_versions as associated resources/links and adds it to representable attrs order.
lib/api/v3/work_packages/schema/work_package_schema_representer.rb	Adds schema entry for observed_in_versions as always-multi-valued collection.
lib/api/v3/work_packages/schema/specific_work_package_schema.rb	Delegates assignable_observed_in_versions to contract.
lib/api/v3/work_packages/eager_loading/checksum.rb	Extends versions checksum to include all work_package_versions kinds (incl. observed_in).
lib/api/v3/queries/schemas/observed_in_versions_filter_dependency_representer.rb	Adds filter dependency representer class for observed-in versions filter.
lib/api/v3/activities/activity_eager_loading_wrapper.rb	Switches eager loading from kind-scoped to unified work_package_version_journals.
lib_static/plugins/acts_as_journalized/lib/journal_changes.rb	Adds observed_in_versions changeset diffing and refactors change aggregation.
frontend/src/app/shared/components/fields/edit/field-types/versions-edit-field.component.ts	Updates documentation to cover both version collections in the versions edit field.
frontend/src/app/shared/components/fields/edit/edit-field.initializer.ts	Registers versions edit field for observedInVersions in addition to targetVersions.
frontend/src/app/features/work-packages/components/wp-edit/work-package-changeset.ts	Excludes empty targetVersions/observedInVersions link collections on create payloads.
docs/api/apiv3/tags/work_packages.yml	Documents observedInVersions in the work packages tag table.
docs/api/apiv3/components/schemas/work_package_write_model.yml	Adds observedInVersions to the write model schema docs.
docs/api/apiv3/components/schemas/work_package_schema_model.yml	Adds observedInVersions to schema model docs.
docs/api/apiv3/components/schemas/work_package_model.yml	Adds observedInVersions to work package model docs + example.
config/locales/en.yml	Adds English label for observed_in_versions.
config/initializers/export_formats.rb	Registers export formatter for observed_in_versions.
app/services/work_packages/activities_tab/paginator.rb	Eager-loads unified work_package_version_journals for activities tab pagination.
app/services/journals/create_service/work_package_version.rb	Expands journaling to include observed_in kind.
app/models/work_package/versions.rb	Adds observed-in associations and effective_observed_in_versions for pending overrides.
app/models/work_package/journalized.rb	Registers observed_in_versions as a formatted journal field.
app/models/work_package/exports/formatters/observed_in_versions.rb	Adds export formatter producing observed-in version names.
app/models/queries/work_packages/selects/property_select.rb	Adds observed-in versions select with SQL for sorting and grouping.
app/models/queries/work_packages/filter/version_filter.rb	Switches to generic FilterOnWorkPackageVersionsMixin and defines version_kind.
app/models/queries/work_packages/filter/target_versions_filter.rb	Switches to generic mixin and defines version_kind.
app/models/queries/work_packages/filter/observed_in_versions_filter.rb	Adds observed-in versions query filter using generic mixin.
app/models/queries/work_packages/filter/filter_on_work_package_versions_mixin.rb	Generalizes target-version-only mixin to kind-based version filtering.
app/models/queries/work_packages.rb	Registers the new ObservedInVersions filter in WorkPackage queries.
app/models/journal.rb	Registers ObservedInVersions formatter and derives kind-scoped version journal arrays in memory.
app/models/activities/fetcher.rb	Updates activity journal eager loading to use unified version journals association.
app/contracts/work_packages/base_contract.rb	Adds attribute contract entry for observed_in_versions with assignability validation.