Combat stats round 2 from arena round 1 findings

Round 1 findings: concentrated fleets won all four equal-threat
cross-tier matchups flawlessly; glass destroyers beat armored; repair
escort beat raw numbers flawlessly; two stations annihilated a 3x
threat swarm through 200 m approach fire; team 1 won all three mirror
matches (possible sim bias, recorded as action item 6, plus action
item 7 for HP-margin logging).

Knob changes, deliberately few for clean attribution: concentration
tax on m/l gun DPS (railgun_m damage 17 -> 14, railgun_l 70 -> 52),
armor_plates 640 -> 1000 HP (~31 HP/threat: killing removes enemy DPS
while surviving merely delays, so HP must be cheaper than DPS), repair
25 -> 12 HP per cycle (~1 HP/s per threat: in-combat sustain removes
enemy DPS and must be priced like DPS), station range 200 -> 120. Gun
ranges untouched; if concentration still wins flawlessly in round 2,
the range ladder is the next suspect. Anchors and findings documented
in content_design.md; fitted threat values are unaffected by stat
changes, so the arena suite counts stay valid.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DyCu8vwChKMbLJQ3xosYEN

docs/content_design.md

@@ -446,24 +446,34 @@ All combat stats derive from a few anchors so that power-per-threat holds
 by construction; the arena suite in `bin/balancing/data/balancing.toml`
 verifies it empirically. Change the anchors first, re-derive stats second.
 
-- **Weapon DPS ≈ 0.6 per threat of weapon contribution**, mildly
-  diminishing with gun size, compensated by the range ladder:
-  railgun_s 2 dmg × 2.0 Hz = 4.0 DPS at 6.5 threat (0.62), range 50;
-  railgun_m 17 × 1.5 = 25.5 at 43.5 (0.59), range 70;
-  railgun_l 70 × 0.8 = 56 at 102 (0.55), range 100.
+- **Weapon DPS per threat pays a concentration tax that grows with gun
+  size**: railgun_s 2 dmg × 2.0 Hz = 4.0 DPS at 6.5 threat (0.62),
+  range 50; railgun_m 14 × 1.5 = 21 at 43.5 (0.48), range 70;
+  railgun_l 52 × 0.8 = 41.6 at 102 (0.41), range 100. Arena round 1
+  (see below) showed that at equal threat, concentrated fleets win
+  flawlessly with a flat-ish DPS curve — concentration itself (focus
+  survivability, range, no losses-to-attrition of own DPS) is worth
+  paying for, so bigger guns get less raw DPS per threat.
 - **Hull HP = 15 per threat of hull contribution** (incl. ship base
   time): drone 60, frigate 300, destroyer 550, cruiser 1500,
   battlecruiser 2700, battleship 7500, dreadnought/carrier 15500.
-- **Armor HP = 20 per threat** — a premium over hull HP because armor is
-  pure HP with no capability: armor_plates adds 640 HP at 32 threat.
+- **Armor HP ≈ 31 per threat** — a strong premium over hull HP (15)
+  because armor is pure HP with no capability, and fights snowball:
+  killing enemies removes their DPS, while surviving merely delays —
+  so a point of HP must be cheaper than a point of DPS.
+  armor_plates adds 1000 HP at 32 threat (arena round 1: at 640 the
+  all-guns destroyer beat the armored one).
 - **TTK check:** a mirror cruiser duel (51 DPS vs 2140 EHP) lasts ~42 s —
   inside the 30–60 s parity-fight band implied by the 25-ship fleet
   target. Capital mirrors run longer (~90 s), deliberately.
-- **Repair ≈ 2 HP/s per threat:** repair_tool heals 25 HP × 1 Hz at 13
-  threat. Salvager: collection range 60 (was a nonsensical 500, beyond
-  any sensor), cargo 20, 0.5 collections/s. `scrap_despawn_seconds`
-  raised 30 → 120: a capital kill drops hundreds of scrap collected one
-  per cycle, so 30 s despawned nearly everything.
+- **Repair ≈ 1 HP/s per threat:** repair_tool heals 12 HP × 1 Hz at 13
+  threat (arena round 1: at 2 HP/s-per-threat the escorted team won
+  flawlessly — in-combat sustain effectively removes enemy DPS and must
+  be priced like DPS, not like HP). Salvager: collection range 60 (was
+  a nonsensical 500, beyond any sensor), cargo 20, 0.5 collections/s.
+  `scrap_despawn_seconds` raised 30 → 120: a capital kill drops
+  hundreds of scrap collected one per cycle, so 30 s despawned nearly
+  everything.
 - **Mobility ladder is monotone in size** — small = fast and nimble
   (drone 45 m/s, 60 accel) down to capitals (10 m/s, 8 accel); the old
   placeholder had the drone as the least agile ship. Sensor ranges keep
@@ -474,14 +484,29 @@ verifies it empirically. Change the anchors first, re-derive stats second.
   — so modifiers pay off on gun-heavy big hulls and are a waste on small
   ones. Kept at ×1.2/×1.2/(×1.5 range, ×0.8 rate) deliberately.
 - **Stations:** a fresh player station (3000 HP, 25 dmg × 1 Hz,
-  range 200) holds one early parity wave unaided; the enemy station at
+  range 120) holds one early parity wave unaided; the enemy station at
   level 0 matches it exactly and scales per push level
-  (+1500 HP, +12 dmg, +0.1 Hz per level). HQ 5000 HP.
+  (+1500 HP, +12 dmg, +0.1 Hz per level). HQ 5000 HP. Range reduced
+  from 200 in round 1: at 200 (4× a small gun's range) two stations
+  annihilated a 3× threat swarm through approach fire alone — range,
+  not HP, is the station dominance lever.
 - **Known imbalance, accepted:** the carrier loses its equal-threat
   arena until the drone-launching capability exists — the hangar is 224
   threat of dead weight. Do not compensate with stats; fix by
   implementing drones.
 
+**Arena round 1 results (2026-07-04):** mirrors snowball as expected
+(40–50% of the winner survives) but team 1 won all three mirrors —
+possible sim-side bias, under investigation (progression_design.md
+action items 6–7). All four equal-threat cross-tier matchups were
+flawless wins for the concentrated side; glass destroyers beat armored;
+repair escort beat raw numbers flawlessly; two stations shrugged off a
+3× threat swarm. Round-2 knob changes: concentration tax on m/l gun
+DPS (17→14, 70→52 damage), armor 640→1000, repair 25→12, station range
+200→120. Gun ranges deliberately untouched — if concentrated fleets
+still win flawlessly in round 2, the range ladder (kiting) is the next
+suspect, ahead of further DPS cuts.
+
 ## Balancing targets (first pass, July 2026)
 
 The six root numbers for the balancing pass. Every derived value (threat