Show visible signature information in signer validation details #8326

Context

Part of #8321.

A PDF digital signature can exist without a visible signature mark on the page.

LibreSign should make this clear also on the validation page.

This information should be shown as part of the signer details. It is metadata about how the signature is represented in the PDF, not a validation warning.

Expected behavior

In the signer details on the validation page, show whether that signer has a visible signature element.

Suggested field:

Visible signature: Yes

or:

Visible signature: No

Use the existing signer details layout.

Do not use a warning, error or success message for this information.

A signature without a visible element is still a valid digital signature.

Where to implement

The document validation flow already renders signer information through:

src/components/validation/SignerDetails.vue

Add the new field there with the other signer details.

Use the existing NcListItem pattern.

Do not create a new validation section only for this value.

How to detect the value

The API already provides visibleElements in signer data.

Do not add a new backend endpoint or a new database field.

Use the existing signer data:

signer.visibleElements

The value can be decided as:

Array.isArray(signer.visibleElements) && signer.visibleElements.length > 0

If there is at least one visible element:

Visible signature: Yes

If there are no visible elements:

Visible signature: No

Do not try to detect this by reading the PDF in the frontend.

Do not create new logic to match signers and elements when visibleElements is already available on the signer.

Envelope validation

For envelopes, keep this information at document signer level.

A signer may have a visible signature in one document and no visible signature in another document.

Because of this, do not show one global Yes or No value in the consolidated Signers summary.

The value should describe the signer for the specific document being inspected.

Display rules

Show this information for signed signers.

It should appear with the existing signer metadata, such as:

• date signed;
• validation status;
• hash algorithm;
• remote address;
• user agent.

The exact position should follow the current layout, but it should not be inside Validation status, because having no visible signature is not a validation problem.

Tests

Add or update the tests for SignerDetails.vue.

Cover at least:

• signer with one visible element shows Visible signature: Yes;
• signer with several visible elements shows Yes;
• signer with an empty visibleElements array shows No;
• signer without visible elements does not show any warning or validation error;
• existing validation information still renders normally.

If there is already validation-page integration coverage for signer details, extend it with one focused case.

Do not create a complete new validation workflow only for this field.

Out of scope

This issue does not:

• change signature validation;
• change the PDF;
• create visible signature elements;
• change the signer flow from Explain when a signer has no visible signature field #8325;
• change the requester warning from Warn requesters when signers have no visible signature field #8323;
• add a global envelope-level visible signature status.

Good first issue

The API already provides the information needed for this change.

The main work is:

• add visibleElements to the local signer type if needed;
• show one new field in SignerDetails.vue;
• add focused frontend tests.

No backend change, new API or PDF parsing is needed.

Please reuse the existing validation components and keep the change focused.

Additional context

• If you have questions, feel free to ask in this issue.
• Give a ⭐️ star to this repository if you find LibreSign useful and would like to support the project.
• You can also join our community: https://t.me/LibreSign

Done when

• Visible signature: Yes/No is shown in signer validation details.
• The value comes from the existing visibleElements signer data.
• No backend change is added.
• Missing visible elements are not shown as a validation problem.
• Envelope validation keeps the value at document signer level.
• Frontend tests cover visible and non-visible signatures.