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THE PATH

18 changes, in the order that teaches.

The arena is a reference. This is a curriculum: one next thing at a time, ordered so that each unit assumes the one before it. Nothing is locked behind a good score — a node opens as soon as you have attempted the one above it, because re-reading a challenge whose answer you have already seen teaches nothing.

START HERE

The batch that reports success

Open it
UNIT 1

First read

0/2

Two changes where the defect is real, the description is confident, and the mechanism is visible if you read the whole function rather than the diff.

  1. The batch that reports success

    A promise nobody waited for. Every test passes.

    Review75s to triage
    —

  2. Retry the charge

    Attempt the one above to open this.

    Review90s to triage
    —
UNIT 2

What the description does not say

0/2

The agent's note is fluent, specific, and partly untrue. These two are about reading the claim first and then checking whether the code makes it.

  1. Five per hour

    Attempt the one above to open this.

    Review90s to triage
    —

  2. Download your invoice

    Attempt the one above to open this.

    Review80s to triage
    —
UNIT 3

Restraint

0/2

The unit everybody scores worst on. One of these two should be approved, and being asked to approve directly after two units of finding defects is the point.

  1. Last week in review

    Attempt the one above to open this.

    Review100s to triage
    —

  2. Nothing wrong with it

    Attempt the one above to open this.

    Review120s to triage
    —
UNIT 4

The edges

0/3

Injection, tenancy, and a number that stops fitting. Three defects that live at a boundary the type checker does not span — and two of them are real, mined out of public git history with the fix commit as the answer key.

  1. Search the projects

    Attempt the one above to open this.

    Review100s to triage
    —

  2. Make the dashboard fast

    Attempt the one above to open this.

    Review110s to triage
    —

  3. One line faster

    Attempt the one above to open this.

    Review100s to triage
    —
UNIT 5

The record

0/4

Nothing in this unit was invented. Four defects mined out of public git history, where the commit that fixed each one is the answer key and the number beside it is how long it survived review in a repository you have probably shipped.

  1. Joined, not confined

    Attempt the one above to open this.

    Review80s to triage
    —

  2. Normalise the separators

    Attempt the one above to open this.

    Review120s to triage
    —

  3. The limit that is the load

    Attempt the one above to open this.

    Review95s to triage
    —

  4. Counted twice, once

    Attempt the one above to open this.

    Review100s to triage
    —
UNIT 6

Somewhere else

0/3

Three more mined defects, chosen because the line you have to click and the damage it does are in different places — one function down, one request later, one host over. Reading the change is not enough for any of them.

  1. Partial, as declared

    Attempt the one above to open this.

    Review95s to triage
    —

  2. Both, it says here

    Attempt the one above to open this.

    Review100s to triage
    —

  3. Absolute, according to whom

    Attempt the one above to open this.

    Review110s to triage
    —
UNIT 7

Beyond the diff

0/2

The two formats where the answer is not in the change under review. This is where the skill stops being bug-finding.

  1. Rename the field

    Attempt the one above to open this.

    Blast radius~8 min
    —

  2. Five reviewers, one lock

    Attempt the one above to open this.

    Adjudication~9 min
    —