Study — the preflop tree

/study is the product landing: a browsable 8-max preflop decision tree for each solved stack depth. Everything on this screen comes from the preflop packs (HRC solves, 169-class strategies) — see Preflop Pack v1 for the wire contract.

Solutions strip and settings panel

The collapsed strip reads the solved regime in one line:

Solutions   MTT · ChipEV · 8 players · Symmetric · 100bb          ante 0.125bb   berserk_v1 · 20260721T131354Z

Change expands the panel. Every axis shows its options, and options that are not solved are rendered locked with the tooltip "Not yet solved — MTT · ChipEV · 8-max only":

The stack ladder lists the ten depths — 100, 75, 60, 50, 40, 30, 25, 20, 15, 10bb — each with its situation count (the number of decision nodes in that tree). Picking a depth loads its tree and resets the line.

Position cards

One card per seat in table order — UTG, UTG1, LJ, HJ, CO, BTN, SB, BB. The seat to act has a green border; each card carries its stack behind (SB/BB also show what they posted) and a state label: to act, next in, acted, folded, or no decision.

• Seat to act — lists every available action as a colored row: label, size, and the range-wide frequency (share of the arriving range that takes it). Rows are ordered most aggressive on top, fold at the bottom.
• Later seats — also list their actions, slightly dimmed. Clicking one takes it with the folds in between implied; the tooltip spells it out ("folds 2 seats to here").
• Acted seats — show the action taken on this line, colored, with its share of the range.
• Folded seats — dim to 40% with a "Fold" tag.

Line breadcrumb and URL state

The breadcrumb replays the line — Root › UTG Raise 2.5 › BTN Call › … — and every step is a link that re-opens that decision. The current node chip says who is to act, or the terminal kind (Hand over, Multiway flop, All-in runout, Heads-up flop). Reset line jumps back to root.

State lives entirely in the URL:

/study?depth=100&line=fold-r2.5-call

• depth — the ladder depth in bb (default 100; unknown values redirect to /study).
• line — the action ids taken from root, joined by - (raise ids embed the raise-to size, e.g. r2.5; see the node_path grammar). An illegal line redirects to the depth's root.

Any node in any tree is therefore a shareable, bookmarkable link.

The decision area

Below the strip, tabs for the current node:

• Strategy — the 13×13 chart of the acting seat's mixed strategy, a range-wide frequency bar, per-action summary rows (frequency + combo counts), and "Where each action comes from": for each action, the top hand classes contributing combos to it.
• Ranges — the arriving range of each live seat as a 13×13 chart (cells fill to the class's reach weight — the product of the action frequencies that seat took along the line). Actor renders green, other seats blue.
• Breakdown — locked, stated plainly on the tab: per-action EVs arrive when the preflop packs ship EV exports; nothing is fabricated in the meantime.

The tab bar also carries the node's pot geometry: pot, amount to call, players remaining, and effective stack.

When the line closes, the decision area is replaced by the terminal panel — covered next in the preflop → postflop bridge.