Undo system bug fix, Late Registration eligibility checker, and robots.txt.

NewTon DC Tournament Manager v4.2.6 — March 12, 2026

Overview

NewTon DC Tournament Manager Version 4.2.6 delivers a bug fix to the undo system, the first stage of the Late Registration feature in the Developer Console, and a robots.txt for the deployed site.

This release contains no breaking changes and is a drop-in replacement for v4.2.5.

Bug Fix: Undo System — Live Downstream Match Detection

The Problem

The undo eligibility check (isMatchUndoable) only blocked undos when downstream matches were completed. It did not check whether a downstream match was currently live. This meant a match could be undone while a downstream match was actively in progress, potentially corrupting the live match's context.

The bracket hover tooltip had the same gap — it would show "Can Undo" even with a live downstream match in progress.

The Fix

Both the winner's and loser's downstream destinations are now checked for live status (match.active) before allowing an undo. The tooltip now correctly shows Cannot Undo, blocked by FS-2-4 (live) when a downstream match is in progress.

Late Registration — Stage 1 (Eligibility Checker)

A new Late Registration command has been added to the Developer Console (amber, after Toggle Read-Only). This replaces the former "Bracket Editor" placeholder and represents the first stage of a planned mid-tournament player addition tool.

What Stage 1 Does

Stage 1 is a read-only eligibility checker — it makes no changes to the tournament. It scans all Frontside Round 1 BYE slots and reports how many are eligible to receive a late-registered player.

A BYE slot is eligible if:

Neither its winner nor loser downstream match is live
Neither its winner nor loser downstream match was manually completed

Output

Count: "X of Y FS Round 1 BYE slots eligible for late registration"
Fairness warning: if some slots are ineligible, warns that the draw cannot be fully fair
Blocking matches: lists each ineligible slot with the specific blocking match and player names (e.g. FS-2-4 (Frank vs Harry, live))
Replay warning: explicitly states that any stopped or undone matches must be replayed from the beginning
Clear refusal: if no eligible slots exist at all, the command refuses with a plain explanation

What's Coming

Stage 2 will add the new player to the participant list (reusing the existing registration function). Stage 3 will randomly place the player in an eligible BYE slot, undo the auto-advance, record a transaction, and re-render the bracket.

SEO

robots.txt added to repo root — allows all crawling and signposts /llms.txt for AI services

Files Changed

js/bracket-rendering.js — isMatchUndoable() and tooltip function updated with live downstream match checks
js/analytics.js — commandBracketEditor renamed to commandLateRegistration and implemented as eligibility checker; showCommandFeedback updated with amber warning status
tournament.html — Dev Console menu entry renamed to "Late Registration"
robots.txt — new file
js/main.js — version bumped to v4.2.6
CHANGELOG.md — v4.2.6 entry added

Migration from v4.2.5

No migration required. Fully compatible with all existing tournaments and saved configurations.

NewTon DC Tournament Manager v4.2.6 — undo system bug fix, Late Registration eligibility checker, and robots.txt.

Download v4.2.6

Previous Releases

Latest release
v4.2.5 — March 11, 2026 — Landing page improvements and a Bracket Editor placeholder in the Developer Console.
v4.2.4 — March 10, 2026 — Proper Single Elimination match length configuration and colour-coded Chalker leg averages.
v4.2.3 — March 10, 2026 — Landing page redesign with retro comic theme by Nano Banana.
v4.2.2 — March 9, 2026 — Landing page fix, cleaner card layout.
v4.2.1 — March 8, 2026 — Cleaner cards, clearer brackets, better discoverability.
v4.2.0 — March 3, 2026 — Single Elimination: one shot, no second chances.

For older releases, see the GitHub releases page.