include diehammer plan docs

Diehammer - 40k Die Modifier Research.md

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+# Warhammer 40k Die Modifiers — Research (11th Edition, current as of Aug 2026)
+
+Reference for the Diehammer app's die-modifier research task. Sourced from the 11th Edition core rules (released 2026) via Goonhammer/Tabletop Battles and ThriftHammer's keyword cheat sheet.
+
+## Core roll mechanics to support
+
+- **Flat modifiers to Hit**: +1/-1. Net modifiers to a single hit roll are capped at ±1 regardless of how many sources stack.
+- **Flat modifiers to Wound**: +1/-1. Same net cap of ±1 applies.
+- **Unmodifiable results**: an unmodified roll of 1 always fails; an unmodified roll of 6 always succeeds (hit and wound rolls).
+- **Rerolls**:
+  - Reroll 1s (to hit or to wound)
+  - Reroll all failed rolls
+  - Reroll all rolls ("fishing" — used with Sustained Hits/Devastating Wounds to chase crits)
+
+## Hit roll keywords
+
+- **Sustained Hits X**: unmodified hit rolls of 6 generate X additional automatic hits. Bonus hits are not themselves Critical Hits.
+- **Lethal Hits**: unmodified hit rolls of 6 auto-wound (skip the wound roll). Not a Critical Wound, so the target still gets a save.
+- **Torrent**: no hit roll at all — automatic hits equal to the weapon's Attacks characteristic.
+- **Psychic**: ignores all modifiers to the hit roll (cover, stealth, etc. all disregarded).
+- **Heavy**: +1 to hit if the firing model moved less than 3" that turn (unit-wide, all-or-nothing).
+- **Plunging Fire**: +1 BS when shooting from 3"+ elevation.
+- **Indirect Fire**: target always treated as in Cover (-1 to hit), no rerolls to hit allowed.
+- **Cover** (changed in 11th): now a straight -1 to the hit roll, not a save bonus.
+- **Ignores Cover**: negates the Cover -1 to-hit penalty.
+- **Stealth**: grants the Benefit of Cover even in the open (was a direct -1 to hit in 10th).
+
+## Wound roll keywords
+
+- **Devastating Wounds**: a Critical Wound (unmodified 6, or lower threshold via Anti) bypasses armor and invulnerable saves entirely. Only Feel No Pain can still apply.
+- **Anti-X (keyword) Y+**: against units with the matching keyword, wound rolls of Y+ count as automatic Critical Wounds.
+- **Twin-linked**: reroll wound rolls (ranged and melee).
+- **Lance**: +1 to wound if the unit charged this turn.
+- **Critical Wound**: bypasses all armor/invuln saves outright; only affects one model regardless of Damage stat.
+
+## Damage-stage modifiers (not hit/wound, but relevant to a full simulator)
+
+- **Melta X**: +X Damage when firing within half range (roll separately for models in/out of half range; apply after base damage, before damage-reduction effects).
+- **Feel No Pain X+**: post-save roll-off to ignore a wound entirely.
+- **Hazardous**: post-attack self-damage roll (fail on 1-2 → Mortal Wound(s), no saves).
+
+## Implications for Diehammer's modifier system
+
+To "accommodate" this fully, the die-modifier engine likely needs to support, per roll type (hit/wound/save):
+1. A stacking flat-modifier input, auto-capped at ±1 net (hit/wound only — saves aren't capped the same way, since AP reduces save target directly rather than via a capped modifier).
+2. A reroll mode selector: none / reroll 1s / reroll all failed / reroll all.
+3. A "critical trigger" layer separate from raw success — since Sustained Hits, Lethal Hits, and Devastating Wounds all key off *unmodified* natural 6s (or a lowered Anti-X threshold), not the modified result.
+4. Flags for "ignore all modifiers" (Psychic) and "auto-success, no roll" (Torrent).