feat(napkin-math): sharper severity wording in Suggested next actions + MARGINAL bucketing

[neoneye]

Summary

ChatGPT review of the v44 casino_royale assessment flagged two wording issues — both in summarize_assessment.py, both pure rendering, no schema change.

1. Suggested next actions item #1 understated DOOM

Old:

"1 gate(s) currently fail at the 50% pass-rate bar."

That phrasing reads identically whether the worst gate is FRAGILE at 49% or DOOM at 0%. ChatGPT: "the worst gate has 0.0% pass rate, which is not just 'below 50%'; it is a structural failure under current bounds."

New (mixed example):

"2 declared gates in the DOOM band; 3 in the FRAGILE band. Worst: sponsor_profitability_window_margin_days at 0.0% pass rate under current bounds."

New (single-DOOM example, matches casino_royale v44):

"1 declared gate in the DOOM band. Worst: sponsor_profitability_window_margin_days at 0.0% pass rate under current bounds."

The summary distinguishes DOOM count from FRAGILE count and names the worst gate by id and pass rate.

2. MARGINAL "coin-flip" wording over-fired at 79.8%

Old Decision implications for MARGINAL was a single template:

"passes 79.8% of runs — close enough to coin-flip that downstream commitments should not assume it holds."

ChatGPT: "At 79.8%, it barely misses ROBUST. Calling it 'close enough to coin-flip' is too harsh. It is not coin-flip; it is near the ROBUST threshold."

The MARGINAL band is 50–80%. A 51% pass is genuinely coin-flip; a 79% pass is one slip from ROBUST. Bucketed at 70%:

• ≥ 70%: "just below the ROBUST band. The gate passes in most runs, but downstream commitments should not treat it as secure."
• < 70%: keeps the "close to coin-flip" framing.

Test plan

• Smoke 9/9, unit 50/50 green.
• v44 casino_royale regenerated locally: item fix: Add UTF-8 encoding for markdown file operations #1 now reads 1 declared gate in the DOOM band. Worst: sponsor_profitability_window_margin_days at 0.0% pass rate under current bounds. and the 79.8% AML-adjusted NOI gate's Decision implications row now reads just below the ROBUST band. The gate passes in most runs, but downstream commitments should not treat it as secure.

🤖 Generated with Claude Code

[neoneye]

Superseded by #723, which bundles these two wording fixes with the v45 saturated-gate-exclusion explainer.