Task 964 — Implement 'used on test project' display in issuetrackerView edit (gap vs legacy)

Issue: #964 Status: IMPLEMENTED & VERIFIED (2026-09-24)

The gap

Legacy edit form gui/templates/dashio/issuetrackers/issueTrackerEdit.tpl:73-119 (displayUsedBy) draws an info icon (fa-info-circle, title show_hide_linked_to_project) next to the Name field that toggles a hidden usedByOuter/usedByEnvelope block showing:

• Used on Test Project (used_on_testproject) followed by one line per test project linked to the tracker, or
• Issue Tracker Not Used (Linked) (issuetracker_not_used_linked) in italics when the tracker is linked to nothing.

The project set comes from lib/issuetrackers/issueTrackerEdit.php:140-153 (initializeGui → issueTrackerMgr->getLinks($argsObj->id), which purges dead links first then maps testproject_id → testproject_name via tlIssueTracker::getLinks() (class.php:516-543). Browser test (legacy): editing tracker id=1 listed prj_its under "used on testproject".

The modern screen dropped it:

• api/issuetracker/index.php GET /{id} returned the tracker row through trackerToJSON(), which defaults link_count => 0 and links => [] — the single-item route was never enriched with the linked projects (only the LIST route attaches links via getLinkSet() for the #963 delete tooltip).
• gui/templates/issuetracker/issuetrackerView.html trackerModal had only Name/Type/Configuration fields, no info icon, no way to see which projects use a tracker before editing/deleting it.

Investigation (measured)

• Fixture: issuetrackers id=1 Bugzilla Tracker linked to Project Alpha (testproject id 1) + Project Beta (id 2); id=2 GitLab CI unlinked.
• BFF GET /api/issuetracker/index.php/1 → link_count:0, links:[] (measured BEFORE fix) despite two testproject_issuetracker rows.
• Browser: edit modal on Bugzilla Tracker → DOM probe hasUsedBy:false, no linked-project info anywhere (measured).

Fix

BFF api/issuetracker/index.php (single-item GET route):

• Calls $mgr->getLinks($id) (the same map the legacy initializeGui uses), attaches links (linked test-project names) + link_count to the item payload before trackerToJSON().

HTML gui/templates/issuetracker/issuetrackerView.html:

• Modal: fa-info-circle anchor (localized tooltip it.showHideLinkedToProjects) beside the Name label + hidden #usedByOuter/#usedByEnvelope block (mirrors issueTrackerEdit.tpl:167-184).
• JS toggleUsedBy() — port of legacy displayUsedBy(): toggles collapse; renders it.usedOnTestproject + one line per linked project name (HTML- escaped) or italic it.notUsedLinked when empty (create + unlinked states).
• editTracker() feeds usedByProjects from r.item.links; showCreateModal() resets to [] (legacy create: $gui->testProjectSet null → not-used state); hidden.bs.modal collapses the block on close.

i18n — new keys it.usedOnTestproject, it.notUsedLinked, it.showHideLinkedToProjects added to ALL 10 locale bundles (en/ro/de/es/fr/it/ja/pt/ru/zh), each validated with python3 -m json.tool. Locale switch verified (ro).

Verification

• Linked tracker (Bugzilla Tracker): toggle → "Used on Test Project" + "Project Alpha" + "Project Beta"; second click collapses; reopen resets.
• Unlinked tracker (GitLab CI): toggle → italic "Issue Tracker Not Used (Linked)".

• Create modal: toggle → "Issue Tracker Not Used (Linked)" (create parity).
• BFF parity: GET /{id}/1 → link_count:2, links:[Project Alpha, Project Beta]; GET /{id}/2 → link_count:0, links:[].
• Locale RO: tooltip "Arată/Ascunde (Legat de proiecte)"; linked envelope "Folosit în proiectul de test / Project Alpha / Project Beta"; unlinked "Urmăritor de probleme neutilizat (nelegat)".
• Event Viewer / events table: no new Error/Warning; browser console clean.

Test cases

Appended to tmp/TLU_Test_Cases.md (Suite 964, 6/6 PASS); CHANGELOG updated.

Status: DONE — closed in #964.