[0xLeif]

Safari can return a lost WebGL context before delivering its loss event, or refuse context/resource creation. The viewer previously retried initialization on every redraw, producing hundreds of context requests. Cache startup failures and detect loss directly during setup/drawing, so GPU work pauses until restoration while Slice editing and Preview remain usable. Rebuild once after restoration with source, camera and selected slice retained.

Validation:

• Complete Chromium/WebKit suite: 256 passed, including all 293 text examples, binary/composition/folder inputs, size bounds and existing camera/picking/edit checks.
• Two additional genuine early-loss checks passed, plus missing/already-lost startup and all five null GPU-resource cases. The pre-fix startup regression made 263 context requests; repaired initialization makes one.
• Native Safari 26.5.2 independently verified real startup loss, Slice erase/Undo while paused and one restoration rebuild. Screenshot and source hashes are in docs/evidence/viewer-context/.
• Pinned Fledge 1.7.2 / Trust 1.2.2 passed all eight verification steps, four strict specs, 55/55 source coverage and Augur proceed (risk 33). Actual unsigned agent:codex provenance is recorded for all three feature commits; the unchanged strict signature/reviewer policy rejects it and progressive Trust reports degradation. No trusted signature or human review is claimed.
• Strict SpecSync verification passed under the existing approved canvas-recovery scope. Acceptance/archive is pending closing review.

The intermittent Safari/GPU cause remains unproven; this repairs the confirmed application retry gap. The matching site PR529 imports implementation 2cce498 verbatim.