W18 is the model layer's first true cadence test under the new weekly Pulse: six new tree rows across five vendors, two distribution earthquakes (Microsoft / OpenAI exclusivity formally ends, GPT-5.5 + Codex + Bedrock Managed Agents land natively on AWS), and the first independent UK AISI sabotage evaluation showing Opus 4.7 actually got safer than 4.6 while Mythos Preview showed a 65% reasoning-output discrepancy.
The procurement read shifted in two ways: closed-frontier intelligence is now decoupled from cloud residency for the first time (Bedrock-native GPT-5.5 closes the Azure-only gap), and the open-weights ceiling closed to 6 points behind GPT-5.5 on the AA Intelligence Index — a year ago that gap was 13.
The architecture signal: hybrid attention plus 11x-30x sparse-MoE ratios are now the default at both the open frontier (MiMo, DeepSeek, Kimi) and the specialist edge (OpenAI Privacy Filter, Laguna XS.2, Nemotron Nano Omni), so KV-cache and active-parameter footprint are diverging from total parameter count as the dominant procurement variables.
The W17 watchlist's predicted closed-frontier coding response resolved as GPT-5.5 itself replacing GPT-5.3-Codex as the in-product Codex default rather than a separate SKU; Anthropic's response remains Opus 4.7 generally available with no -Codex variant — the era of named coding-tier sub-SKUs may be over for the leading two labs.
For the May 2-9 window, the load-bearing catalysts are Anthropic's response to the AISI Mythos disclosure, Moonshot / DeepSeek free-token responses to Xiaomi's 100T Orbit Plan, and whether Google breaks its post-Gemini-3.1-Pro silence.