Net-new in-app ISTQB certification reference + CTFL v4.0 syllabus hub for TestLink, added as the Documentation ASIDE section's fourth entry (below Documentation, Learn Testing and Accessibility Resources). TestLink 1.9.20 shipped no such screen, so this is a 2.0.1 enhancement rather than a legacy migration; it mirrors the #1059 Accessibility Resources hub and the #1060 Learn Testing hub patterns.

Issue #1053 asks for a discoverable, official ISTQB reference inside TestLink so testers can reach the certification levels, the CTFL v4.0 syllabus structure and the authoritative istqb.org resources (syllabi, certification pages, glossary) without leaving the application.

Layer	File
Screen	gui/templates/documentation/istqbSyllabus.html (Dashio standalone HTML/JS/CSS)
BFF	api/istqb/index.php (GET|HEAD ?action=init, session auth + same-origin guard)
Wiring	$actions->istqbSyllabus in lib/functions/common.php, consumed by api/aside/index.php section 12 (Documentation)
i18n	istqb.* (43 keys) + footers.istqbSyllabus in all 10 client bundles; $TLS_title_istqb_syllabus in all 19 server locales

• What is ISTQB? — an intro card explaining the vendor-neutral certification body and the CTFL Foundation Level syllabus.
• Certification levels (4 cards, each linking to the official istqb.org page): Certified Tester Foundation Level (CTFL), Advanced Level (CTAL), Expert Level (CTEL) and the Specialist certifications.
• CTFL v4.0 syllabus chapters (6 numbered cards): Fundamentals of Testing, Testing Throughout the SDLC, Static Testing, Test Analysis and Design, Managing the Test Activities, Test Tools.
• Official resources (4 external links, all authoritative — no invented URLs): istqb.org home, the CTFL v4.0 certification page, the full certification catalogue and the official ISTQB glossary.
• Related in TestLink — in-context deep links to the Learn Testing hub, the Accessibility Resources hub, the Test Strategy overview and the Documentation hub.

• Live search — a toolbar filter over level titles/descriptions, chapter titles/descriptions and resource labels/descriptions; matching cards are hidden and a distinct no-match empty state (istqb.noResults) is shown only when every section is empty.
• Locale switcher — the standard TLi18n switcher; the whole page follows the selected bundle (English + Romanian + German + Spanish + French + Italian + Portuguese + Russian translated, Japanese/Chinese fall back to English).
• Refresh — reloads the hub from the BFF.

• Session auth (401 anonymous) + bffSameOriginGuard(); GET|HEAD only (405 on a same-origin POST, 403 on a foreign-origin write).
• Unknown/missing action → 400.
• Returns istqb.* keys only (no server-side hardcoded strings), so every label is translated client-side from the same bundles the rest of the UI uses.
• JSON headers + no-store caching.

$actions->istqbSyllabus in lib/functions/common.php resolves to /gui/templates/documentation/istqbSyllabus.html?<ctx>; api/aside/index.php section 12 renders it as the fourth Documentation item with the server label title_istqb_syllabus. The Documentation, Learn Testing and Accessibility Resources entries are unchanged.

• API contract: 200 action=init → 4 levels + 6 chapters + 4 resources + 4 related links, all labels as istqb.* keys; 401 anonymous; 400 unknown action; 405 same-origin POST; 403 foreign-origin.
• Browser (admin): 4 level cards + 6 chapter cards + 4 resource cards + 4 related links render; search static → 1 level + 1 chapter; a no-match query shows the empty state and clearing restores all; Română switch → Programa ISTQB, Deutsch switch → ISTQB-Lehrplan, Chinese → English fallback with no raw keys; console clean (0 messages).
• ASIDE: GET /api/aside/index.php?action=init → ['documentationHub','learnTesting','accessibilityResources','istqbSyllabus'] with the resolved href and fas fa-certificate icon.
• i18n: all 10 client bundles valid JSON; bash ai/verify_i18n_coverage.sh → 9 passed / 0 failed (7719 keys); $TLS_title_istqb_syllabus present in all 19 locale/*/strings.txt (all php -l clean).
• Event Viewer: no new Error/Warning.
• Coverage suite: TLU_REQUIRE_SUITE="Issue #1053" → 24 checks, none lost.

Result: 24/24 PASS.