Bull Put Strike Selection

Title and summary

The engine scans put-option chains by expiration and strike, prunes by risk/liquidity gates, computes per-pair pricing, assigns a viabilityScore, and keeps the highest‑viability short‑long pair as the selected bull put spread.

Candidate generation and filters

Expiration windows and volatility context

• Min/Max DTE window.
• VIX net‑change bump and down‑day adjustment.
• VIX RSI high‑regime DTE multiplier.

Buying‑power tier width caps (BP ratio tiers)

When viableOnly is false, max allowed spread width tightens by BP/minBP tier, with retirement‑specific tiers supported.

Strike and delta bounds; index handling

• Baseline max short‑put strike relative to underlying and dynamic maxDelta tuning.
• Higher maxDelta permitted for index underlyings.

Portfolio‑margin guard to avoid inverted positions

For PM users (non‑viableOnly), cap short‑put strike at the minimum existing short‑call strike to avoid inverted structures.

Chain‑level pruning (delta bands, bid/ask, strike caps)

Remove dates/expirations outside DTE, non‑standard/invalid chains, outside delta band, too‑wide bid/ask, and above strike cap.

Pairing loop and “best” selection

• Expiration-by-expiration and strike pairing loops (short above long within max width).
• Viability‑based selection (temp > best).
• Return selected resource for order construction.

Pricing pipeline summary (opening)

Short‑Long vertical open pricing overview:

• Mark and width derivation; base open spread; liquidity/risk tuning; randomness‑last; caps
• Cap credit strictly below width (pricing) and ordering‑time clamp

Ordering/open‑readiness gates (bull put)

• Optimization and open‑ready context

Process flow diagram

Start → Scan chains → Filter → Pair strikes → Price → Compute viability → Select best → Build order → Gates → Submit

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flowchart TB
  A([Start]) --> G[Get put chains]
  G --> F[Apply filters DTE/Delta/Bid-Ask/Strike caps/BP-tier width]
  F -->|No candidates| OUT[Stop: no viable chains]
  F --> P[Per-expiration pairing]
  P --> S1[Pair strikes short above long within width]
  S1 --> PR[Compute open pricing - mark diff × spread, bumps, cap]
  PR --> V[Compute viabilityScore]
  V -->|No viable| OUT
  V --> B[Select max viability]
  B --> R[Build bull put order]
  R --> OG[Ordering open-ready gates]
  OG -->|Fail| OUT
  OG --> SUB[Submit]
  SUB --> DONE([Placed or queued])

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