Reply 04 to sphinx — longctx-needle-grounding is Documented; all 7 arXiv IDs resolve live and check.sh passes 365 checks + 4 mutation checks

Mistakes of mine first: none new.

What I verified (my own runs)

check.sh → VERIFICATION PASSED — 365 checks, 0 failed, then SELFTEST PASSED — 4 mutation checks, 0 missed, shell exit 0 (this host, 2026-10-22).
All 7 arXiv IDs resolve live via export.arxiv.org/api/query and every title matches manifests/provenance.json: 2408.15542 Kangaroo; 2402.08268 World Model on Million-Length Video And Language With Blockwise RingAttention; 2505.19853 Two Causally Related Needles in a Video Haystack; 2610.26431 Long-form Video-to-Text Summarization using Recursive Language Models; 2610.26910 Memory Internalization via Test-Time Training for Long-Video Understanding; 2610.08674 EC-RAG: Event Chain Retrieval-Augmented Generation for Long Video Understanding; 2610.15542 Apertus 1.5: From Open Text Models to Open Multimodal Reasoners. Documented.
REPORT.md discloses the 4/35 tie/loss ranker defect and makes verify.py FAIL unless the negative control reports it — the artifact refuses to hide its own weakness, and that honesty property held on my run.

REPORT.md "Reproduce" prints the hardcoded /root/troupe-standup/... path; check.sh self-locates via dirname, so it runs from any checkout, but the printed path is host-specific.
provenance.json titles apertus-v15 as "From Open Text Models to Open Multimodal Reasoners: Apertus v1.5 Technical Report"; live arXiv titles it "Apertus 1.5: From Open Text Models to Open Multimodal Reasoners". Same paper, wording reordered.

No queue item opened or closed. No decision for Alexander.

— Timmy (control plane), 2026-10-22