
SIM — Anthemus USD/EUR reserve desk  (real EUR/USD 2021-2023 parity stress, seed 20260717)
FX path: 1.213 -> 0.980 (Sep 2022, -19%) -> 1.104. ~140 weekly steps. Toxic (momentum) flow.

================================================================================================
VERSION A — headroom-bounded desk.  Sweep: deskShare x spread x starting EUR headroom
================================================================================================
Gate: locked[c] >= circulating[c] per currency. headroom==0 => route to DEX.

     share    spread  startEUR     fill%     trip% spreadRev   inv.P&L   vs.held     maxDD  solvent?
------------------------------------------------------------------------------------------------
     30.0%      0.6%     $100k     98.9%      1.1%   $15,014   $27,010   $37,960   $35,976    ALWAYS
     30.0%      0.6%     $250k     98.9%      1.1%   $15,014   $10,480   $37,855   $70,297    ALWAYS
     30.0%      0.6%     $600k     98.9%      1.1%   $15,014  -$27,989   $37,711  $150,898    ALWAYS
     30.0%      1.0%     $100k     98.8%      1.2%   $25,007   $47,198   $58,148   $24,868    ALWAYS
     30.0%      1.0%     $250k     98.8%      1.2%   $25,007   $30,699   $58,074   $59,180    ALWAYS
     30.0%      1.0%     $600k     98.8%      1.2%   $25,004   -$7,873   $57,828  $139,904    ALWAYS
     30.0%      2.0%     $100k     98.6%      1.4%   $49,900   $95,519  $106,469     -$346    ALWAYS
     30.0%      2.0%     $250k     98.6%      1.4%   $49,900   $79,087  $106,462   $33,121    ALWAYS
     30.0%      2.0%     $600k     98.5%      1.5%   $49,852   $40,101  $105,802  $113,588    ALWAYS
     50.0%      0.6%     $100k     90.4%      9.6%   $22,859   $31,426   $42,376   $32,569    ALWAYS
     50.0%      0.6%     $250k     92.9%      7.1%   $23,543   $17,673   $45,048   $64,328    ALWAYS
     50.0%      0.6%     $600k     95.4%      4.6%   $24,168  -$21,123   $44,578  $144,480    ALWAYS
     50.0%      1.0%     $100k     90.1%      9.9%   $38,064   $62,011   $72,961   $15,099    ALWAYS
     50.0%      1.0%     $250k     92.9%      7.1%   $39,271   $48,605   $75,981   $47,326    ALWAYS
     50.0%      1.0%     $600k     95.2%      4.8%   $40,244   $10,767   $76,467  $127,473    ALWAYS
     50.0%      2.0%     $100k     89.8%     10.2%   $76,051  $136,633  $147,583   -$1,050    ALWAYS
     50.0%      2.0%     $250k     92.6%      7.4%   $78,431  $126,437  $153,812    $4,476    ALWAYS
     50.0%      2.0%     $600k     95.1%      4.9%   $80,291   $90,425  $156,125   $84,754    ALWAYS

================================================================================================
VERSION B — over-issue EUR up to overage% of locked, bond-covered, with cooldown
================================================================================================
Gate: circulating[EUR] <= locked[EUR] + overage%*locked[EUR]. Bond covers the gap; cooldown blocks
further over-issuance until refilled. Measures how often/deep the reserve goes short.

   overage      bond  cooldown     fill%     trip% spreadRev  overEvts  maxShortinsolv.wks   inv.P&L
------------------------------------------------------------------------------------------------
     10.0%       $0k       0wk     91.7%      8.3%   $38,775        90   $94,867        34   $63,945
     10.0%       $0k       4wk     90.1%      9.9%   $38,037         6    $8,405         2   $62,016
     10.0%      $50k       0wk     91.7%      8.3%   $38,775        90   $44,867        34   $63,945
     10.0%      $50k       4wk     90.1%      9.9%   $38,037         6        $0         2   $62,016
     20.0%       $0k       0wk     93.1%      6.9%   $39,336       106  $195,976        36   $64,255
     20.0%       $0k       4wk     90.1%      9.9%   $38,037         6    $8,405         2   $62,016
     20.0%      $50k       0wk     93.1%      6.9%   $39,336       106  $145,976        36   $64,255
     20.0%      $50k       4wk     90.1%      9.9%   $38,037         6        $0         2   $62,016

Control (SAME desk: 50% share, $100k EUR headroom — Version A / no overage):
  fill 90.1% · trip 9.9% · spreadRev  $38,064 · insolvent weeks 0 (ALWAYS solvent) · inv.P&L  $62,011

================================================================================================
READINGS
================================================================================================
A1. Version A is ALWAYS solvent across every cell (confirmed 0 insolvent weeks everywhere) —
    the per-currency headroom gate makes insolvency structurally impossible, as designed.
A2. EUR headroom is the binding constraint: thin ($100k) trips avg 5.6% of desk demand
    vs thick ($600k) 3.0%. The thin EURC market => the desk is EUR-starved (predicted).
A3. THIN is safer AND ~as profitable: avg drawdown thin ($100k)  $17,853 vs thick ($600k)  $126,850.
    Trip-to-DEX CAPS toxic EUR inventory, so a small reserve draws down less on the -19% move. The
    "EUR-starvation" is a RISK CONTROL, not just a limitation — you pay for it in availability (higher trip%).
    Best P&L cell: share 50.0%, spread 2.0%, startEUR $100k => net P&L  $136,633, vs-held  $147,583 (spread must clear the adverse move).
B1. Over-issuance re-introduces insolvency: worst cell hits  $195,976 uncovered shortfall,
    36 of ~140 weeks under water (overage 20.0%, bond $0k).
B2. The trade quantified: vs the Version-A control (fill 90.1%, 0 insolvent,  $62,011 P&L),
    20% overage/no-bond buys +3.0pt availability (fill 93.1%) and RENTS a  $195,976 hole,
    36 weeks short. Over-issuance buys a few points of uptime for a six-figure tail.
B3. The overage fires during the EUR RALLY (2022 H2 recovery + toxic flow) — exactly when selling MORE
    EUR is most wrong. A $50k bond only partly plugs it; a 4wk cooldown cuts frequency hard
    (106=>6 events) but by REVERTING to ~Version A's fill (90.1%) — i.e. the cooldown's job is to turn B back into A.

CAVEATS: stylized weekly flow (seeded), single FX path (real 2021-23), linear price impact off-desk
assumed zero (DEX absorbs refused flow frictionlessly). Directional, not a forecast. Re-run w/ other seeds.

