dInfinity

Statistics

Design: statistics (option 1w), history (1x), per-set filtering (5b–5c), sessions (6c) and saved-roll statistics (8b) are in the clickable design (design/).

Players care about how their dice behave even though every face is equally likely. dInfinity records enough to answer “how many natural 20s have I rolled this campaign?” without turning into a spreadsheet.

What is recorded

Every completed roll writes one RollHistory row and updates aggregate counters. Rolls that are cancelled (app closed mid-tumble) are discarded.

Per die (keyed by setId + dieId)

• Total number of times this die was thrown
• Count per face value (a histogram)
• Lowest-face count and highest-face count — the “natural 1” and “natural 20” numbers, surfaced prominently
• Mean result, running variance
• Current and longest streaks of highest-face and lowest-face results
• Last rolled timestamp

Dice with duplicated face values (a d6 labelled 1,2,3,1,2,3) count by face value, so lowest/highest are 1 and 3.

Dropped dice (from kh/dl etc.) are still counted in the per-die stats — the die was thrown and landed on that face — but flagged in the history row.

Per standard die type (aggregated across sets)

The same counters rolled up by sides, so “all my d20s” is one line even if some rolls used the brass set and some the doodled one. Sets with non-standard dice appear only in the per-die view.

Per saved roll and per group

• Times rolled, mean total, min/max total observed, last result
• Histogram of totals, shown next to the theoretical distribution from docs/probability.md so the player can see how their Fireballs compare to expectation
• Rolled up per saved-roll group (a character, a game) so “Thorin’s attack rolls this campaign” is one screen

Per session

A session is a user-defined bucket (“Tuesday campaign”). All stats above are also available filtered by session. The current session is selectable from the home screen; by default the active saved-roll group’s name is used as the session, and “Unfiled” when no group is active.

Anomalies (debug)

Counts of in-flight corrections, re-thrown dice and forced settles (see docs/physics-and-rendering.md). Hidden behind a developer toggle.

Screens

• Overview: big tiles for the currently selected die type — natural highs, natural lows, average, total rolls — with a face histogram and a faint line for the expected uniform frequency.
• All dice: table of every die ever rolled, sortable.
• Saved rolls: per-formula history with expected vs. observed graph.
• History: scrollable list of past rolls with breakdowns. A past roll is a record, not something to re-run: there is no replay action and the seed is never shown. Re-rolling a formula means rolling it again.
• Sessions: create/rename/delete. Deleting one moves its rolls to Unfiled.

Storage

Room database. Version 1 is these three tables and nothing else; saved rolls, sessions and the installed-set registry arrive with the screens that need them (docs/TODO.md, Step 4), each as a migration. That is what “migrations from day one” buys: a database that has only ever been created and never migrated is one whose first migration gets written under pressure.

Every version’s schema is exported to data/schemas/ and checked in, and SchemaTest asserts there is one for every version and a migration for every step between them — so a version bump without a migration fails the build rather than a player’s phone. There is no destructive fallback: a player’s natural-20 count is not something to throw away because a schema moved.

roll_history(id, timestamp, session_id, saved_roll_id?, group_id?, formula, total,
             seed, input_blob, breakdown_json, anomalies)
die_stats(set_id, die_id, sides, face_value, count, dropped_count,
          PRIMARY KEY(set_id, die_id, face_value))
die_summary(set_id, die_id, sides, throws, sum, sum_sq, hi_streak, hi_streak_max,
            lo_streak, lo_streak_max, last_rolled_at)

Streaks and sums are updated in the same transaction as the history insert. roll_history is capped at 50,000 rows by default (oldest pruned); aggregates are never pruned. Uninstalling a dice set keeps its rows.

seed and input_blob (the quantised shake samples, or the default throw parameters) are kept so a roll can be reproduced exactly when a bug report needs it. They are internal: no screen shows them, and the export leaves them out. Reproducing a stored roll is a developer action (docs/physics-and-rendering.md, Debug tooling), not a feature of the app.

Export and reset

• Export everything as JSON or CSV via the share sheet.
• Reset per die, per saved roll, per session, or everything, each with a confirmation dialog.
• Nothing is uploaded anywhere. There is no analytics backend; the “statistics” in this document are the player’s, on the player’s phone.

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