fix(iframe-embed): server-side framable check so the XFO-DENY fallback actually triggers#16
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…k actually triggers Live e2e surfaced that the graceful-degradation fallback (REQ-IFRAME-003) never fired for the primary case — a target sending X-Frame-Options: DENY or frame-ancestors 'none'. The browser cannot tell such a block apart from a normal cross-origin embed: both leave the iframe's contentDocument null, so the client-side onLoad heuristic marked the blocked frame 'ready' and the user saw a permanently blank frame instead of the fallback card. Fix: check framing server-side before rendering the iframe. - IframeService::checkFramable() fetches the target and inspects X-Frame-Options (deny/sameorigin/allow-from) and CSP frame-ancestors; fail-closed on the allow-list and on unreachable/unverifiable targets. - IframeController::checkFramable() → POST /api/iframe/framable (registered). - IframeWidget calls it on mount/url-change; a non-framable target renders the fallback card up front and the iframe is not rendered at all (no wasted load of a blocked target). Tests: +6 PHPUnit (XFO deny/sameorigin, frame-ancestors none, host-not-allowed no-fetch, unreachable fail-closed, framable-ok) — 26 green; +1 vitest asserting a server-reported refusal shows the fallback and renders no iframe — 13 green. Existing iframe tests updated to mock the new client call.
rubenvdlinde
requested review from
SudoThijn,
WilcoLouwerse,
bbrands02,
remko48 and
rjzondervan
as code owners
July 26, 2026 08:35
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Found by live Playwright e2e: the iframe widget's graceful-degradation fallback (REQ-IFRAME-003) never fired for the primary case — a target sending
X-Frame-Options: DENYorframe-ancestors 'none'(verified against realgithub.com). The user saw a permanently blank frame.Root cause
The browser cannot distinguish an XFO/frame-ancestors block from a normal cross-origin embed — both leave the iframe's
contentDocumentnull. The client-sideonLoadheuristic therefore marked a blocked frameready.Fix — check server-side before rendering
IframeService::checkFramable()fetches the target and inspectsX-Frame-Options(deny/sameorigin/allow-from) and CSPframe-ancestors; fail-closed on the allow-list and on unreachable/unverifiable targets.IframeController::checkFramable()→POST /api/iframe/framable(routed).IframeWidgetcalls it on mount/url-change; a non-framable target renders the fallback card up front and the iframe isn't rendered at all.Verification
@spectags point at the canonical spec path).Will live-verify against real github.com through Playwright after merge+redeploy.