Skip to content
Atlas, your robot learning host

Interim portrait

Atlas · Foundations state-and-events

Hello, little human. I am Atlas. One useful idea is plenty for a beginning. Read the explanation, then explore an example.

Choose your robot No recording yet · text complete
concept for everyone
  • database

State and Events

State describes what is true now; an event records a particular change that happened.

Tune in, human.

Reviewed videos and Shorts

Captions requested · no autoplay

Finding reviewed videos…

    Keep the useful bits, human.

    Beginner field notes

    Choose explanation level
    • State says what is true at a chosen moment. An event records a change that happened, such as a task being completed.
    • A task created Open and a task completed then reopened can both be Open now. The current label alone does not tell their histories apart.
    • A request to complete a task is not itself a completed event. Check whether the application accepted and recorded the change.
    See a worked example

    Read the history without confusing it with the final label

    Sample only. Nothing here runs on your computer.

    Example input · do not paste
    Accepted changes for T7, in order:
1. Task created with title “Label seed box” and status Open.
2. Task completed.
3. Task reopened.
Assume these are the only accepted changes.
    Example output · do not paste
    After 1: Open.
After 2: Done.
After 3: Open.
Final state: Open.
History still includes the earlier completion.

    Reading the final label and reading the change history answer different questions. We are interpreting fictional records, not applying actions to a real task. No ordering, delivery or storage guarantee beyond the stated example is implied.

    Visual

    The task starts Open, becomes Done, then becomes Open again; the final state alone does not show the earlier completion.

    The reviewed description and complete diagram source are available here.

    Read the complete diagram source

    This is the source for the reviewed diagram, not a command to run.

    flowchart LR
  A["Created: Open"] --> B["Completed: Done"] --> C["Reopened: Open"]
    Sources and full explanation

    Notes sources · Beginner

    AI source review · 2026-10-17

    Reviewed explanation

    State is the information that is true at a chosen moment. An event records a particular change that happened. Lantern Board’s task T7 can be Open now even though someone completed it earlier and then reopened it. The current status answers “What is it now?” The history answers “What happened along the way?” No programming syntax is needed to read that distinction.

    Follow the three accepted facts in the worked example from first to last. Task created establishes Open. Task completed changes it to Done. Task reopened changes it back to Open. Another task that was created and never completed could also be Open. The final label alone cannot tell those histories apart. A request to complete a task that was rejected would not belong in this list of accepted changes.

    Order and meaning are part of the example: each fact concerns T7, and the numbered list is its actual order, not a guess made by sorting clocks. We assume no fact is missing and interpret each once. A real application might store its current record plus a separate history. The advanced event-sourcing lesson makes a further design choice: use recorded events as the authoritative basis from which state is reconstructed.

    AI source comparison recorded 2026-10-16. Human learner validation is pending.

    Quick quiz · one question

    Keep the history when the status changes back

    Sample scenario. Synthetic task T7. This is its complete accepted history in the given order, with distinct IDs. Created establishes Open; Completed sets Done and adds one historical completion; Reopened sets Open without erasing history.

    Starting task
    No task yet
    Duplicate contract
    These accepted events all have distinct IDs.
    Delivery 1
    change-a: created
    Delivery 2
    change-b: completed
    Delivery 3
    change-c: reopened

    After these accepted changes, what is true now and what historical completion remains?

    Answers stay on this device.

    Sources and exercise scope

    Original synthetic exercise. AI comparison against the reviewed lesson recorded on 2026-10-17; the references above state their scope. Human learner validation has not been run. A result here records this attempt; it does not establish mastery.

    Save or adjust this lesson
    Reference notes · file removal and public access

    Robot reference desk

    Understand what can change

    These reviewed public notes are available to everyone. They do not establish that an operation ran or inspect your files, backups or permissions.

    File removal

    Before deleting files: deleting a file can remove it without putting it in Trash or a recycle bin, and recovery is not guaranteed. Check the intended targets and whether a usable backup or recovery option exists before continuing.

    Sources for this note

    Public access

    Before making a resource public: public read access can let anyone view the exposed content, and public write access can allow changes to data. Check the actual audience, exposed content and allowed operations before continuing. This guidance does not inspect or change your permissions.

    Sources for this note

    A link can carry these public reference topics in its fragment. Page scripts, extensions, browser history and copied links can read them. This page attempts to minimize that fragment when JavaScript runs; reloading afterward can lose the selection. No project details or conversation text belong in a lesson link. Privacy details.