Fix Fayda FAN false positive on adjacent date-of-birth dates

[BurningAXE]

JIRA ticket
Will be released in: 2026.3.1

Root cause analysis (for bugfixes only)

First known affected version: 2026.3.0 (Fayda support added in #1748)

• Users reported that scanning a Fayda card sometimes fills the FAN field with two adjacent dates, e.g. 0702 1998 2005 1017 for a card whose date-of-birth line reads 07/02/1998 | 2005/10/17 (Gregorian | Ethiopian).
• FaydaCardOcrReaderUseCase stripped all non-digit characters from each OCR line and then matched ^\d{16}$. The date-of-birth line contains exactly 16 digits once the / and | separators are removed, so it was accepted as a FAN.
• OCR lines are sorted top to bottom and the date-of-birth line sits above the FAN, so whenever OCR read it, it won over the real FAN. On-device diagnostics confirmed the old logic would have returned 2512200020080831 from 25/12/2000 | 2008/08/31 in 6 of 8 frames.

Notable changes

• Added FAN_OCR_PATTERN, which looks for 16 digits within an OCR line, and not part of a longer digit run. OCR sometimes splits the number, so up to 4 groups separated by single whitespace characters are allowed (e.g. 258094592481 5610). Date lines can't match: punctuation between digits isn't accepted, and the 6 groups of a date line whose separators OCR read as spaces (07 02 1998 2005 10 17) exceed the 4-group limit.
• The FAN value is now extracted from the matched part only, so extra text OCR merges into the line (e.g. FAN 8642370540168134) is tolerated.
• FAN_PATTERN (^\d{16}$) is unchanged. It is still used to validate manually entered or edited FANs in ExternalCredentialSearchViewModel.
• Behaviour change: lines like 1234-5678-1234-5678 or 1234.5678.1234.5678 are no longer accepted by OCR. The card prints the FAN as one unbroken 16-digit number, so this was a false-positive risk rather than a supported format.

Testing guidance

• Unit tests in FaydaCardOcrReaderUseCaseTest cover both reported date-of-birth lines, date lines with the | lost or the separators read as spaces by OCR, the FAN appearing below date lines, extra text on the FAN line, and rejected separators.
• Manual: scan a Fayda card with an MFID project. The FAN field should show the number printed above the barcode, never the date-of-birth digits.

Additional work checklist

• Effect on other features and security has been considered
• Design document marked as "In development" (if applicable)
• External (Gitbook) and internal (Confluence) Documentation is up to date (or ticket created)
• Test cases in Testiny are up to date (or ticket created)
• Other teams notified about the changes (if applicable)

🤖 Generated with Claude Code

[Copilot]

🟢 Approved

The focused matching change and regression coverage have no identified blocking issues; tests were inspected but not executed.

No open issues 🎉

What changed in this PR

Fixes Fayda OCR incorrectly accepting adjacent birth dates as a FAN, addressing a regression introduced with Fayda support.

Changes:

• Restricts OCR matching to 16 digits across at most four whitespace-separated groups.
• Extracts FANs from surrounding text while preserving manual validation.
• Adds regression tests for date lines and accepted/rejected formats.

File	Description
feature/​external-credential/​src/​test/​java/​com/​simprints/​feature/​externalcredential/​screens/​scanocr/​usecase/​FaydaCardOcrReaderUseCaseTest.kt	Adds FAN extraction and date-rejection regression tests.
feature/​external-credential/​src/​main/​java/​com/​simprints/​feature/​externalcredential/​screens/​scanocr/​usecase/​FaydaCardOcrReaderUseCase.kt	Replaces digit stripping with constrained OCR matching.

_{Review effort: Balanced}

[meladRaouf]

@BurningAXE Please change the target branch to 2026.3.1 I have created it.

[luhmirin-s]

Could this be a realistic case from OCR? Maybe not all double spaces, but one of them could be.

[sonarqubecloud]

Quality Gate failed

Failed conditions
B Maintainability Rating on New Code (required ≥ A)

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