Practice storage, events, and UI integration — Build the smallest useful slice

PART I

Warm-up

Reconnect with a useful idea before starting practice storage, events, and ui integration. In one or two sentences, describe the input, output or host boundary from the previous exercise that this lesson builds on. If you are arriving directly, skim the worked example first; there is no locked prerequisite.

A rough note is enough. You can revise it after the example.

PART II

Instruction & guided example

Build cache admission before rendering

An integrated feature needs one state story across resource admission, asynchronous results and UI lifetime. Make the handoffs explicit: who owns the job, which revision it reads, where candidate output lives, and which screen generation may display it. The source leaves exact host lifecycle APIs unresolved.

Exercise report screenS generation 7 requests report R on PublicData revision 60. R reserves 24 MiB memory and creates a 12 MiB disposable cache. The cache quota is 40 MiB. S closing prevents further UI updates; a documented background owner may finish or cancel work according to the chosen contract.

Supplied case: Cache already holds 32 MiB of protected active output. New R needs 12 under a 40 MiB quota.

Worked reasoning: Total would be 44, so the cache cannot admit R under the stated policy. Refuse/defer or use a deliberately bounded alternative before claiming the report is ready. Do not delete active output simply to fit the new screen.

Contrast and diagnosis: A UI request does not revoke another owner’s retention guarantee.

Worked reasoning and supplied artifact

// Disposable exercise fixture / host-contract notes; not executable API syntax.
// Supplied input: Cache already holds 32 MiB of protected active output. New R needs 12 under a 40 MiB quota.
// Worked prediction: Total would be 44, so the cache cannot admit R under the stated policy. Refuse/defer or use a deliberately bounded alternative before claiming the report is ready. Do not delete active output simply to fit the new screen.
// Rejected alternative: A UI request does not revoke another owner’s retention guarantee.

Illustrative example from the proposed WillowScript design. The language and WUIX/WMATH/WDB/WAUDIO/WTMP services are not implemented in the supplied source. This site has no interpreter, VM or native host and does not execute or certify the snippet.

Try the guided change

Reconstruct the supplied worked case first: list its inputs, intermediate decisions and final artifact. Compare each row with the explanation and identify exactly where the rejected alternative fails. Then use the changed inputs in Part IV for independent work.

• Write the supplied inputs and initial state before following the example.
• Reconstruct each intermediate calculation or host decision, then compare with the worked artifact.
• Explain why the contrasting alternative fails before attempting the changed inputs in Part IV.

PART III

Take a breather

Step back after the guided example. Look away from the screen, stretch, or reread your prediction. This is an optional learning pause, not a timer or an assessment gate.

When you return, try to name the lesson’s key idea without copying its wording. If that feels difficult, return to Part II and trace one line rather than restarting the entire lesson.

PART IV

Independent practice

Project context: Bounded automation workspace. Build a small, understandable change around practice storage, events, and ui integration.

Use existing cache 28 and new output 12, then 28+13. Compare exact fit with overflow and state retained resources.

What to produce

Use existing cache 28 and new output 12, then 28+13. Compare exact fit with overflow and state retained resources. Include input → intermediate decision/state → predicted outcome, with any required host rule stated explicitly.

• State the intended behavior in a sentence before editing.
• Use only source-backed syntax and the host services whose contract you have been given.
• Record a normal case and a boundary or unavailable-resource case.
• Label hand predictions separately from anything actually measured in a supplied toolchain.

Syntax colors are a reading aid, not a compiler. The line you are editing stays uncolored until you move to a different line; capitalization is never changed. Drafts stay on this browser and code is not executed.

import tmp;
const cache = tmp.create({
    name: "report-cache",
    storage: "ssd",
    maxSize: "2GB",
    lifetime: { duration: "30m", refreshOnAccess: true },
    cleanup: { automatic: true, onCrashRecovery: true }
});

PART V

Self-check

Use this check to notice what to revisit. It does not award a private course grade, block another page or claim to verify compiled code. Every answer has a learning explanation.

You may keep exploring even if you are unsure. Use the hint, compare the trace, and revise your explanation.

PART VI

Recap & small task

Bring the idea back to the mod feature you are building. A useful recap connects the mechanism to a decision you can make in your own code.

• Build cache admission before rendering
• Explain the decision for the supplied case, then independently work the changed fixture.
• Separate source-backed behavior, host requirements and untested predictions.

One small recap task

In one or two sentences, name the decisive rule in “Build cache admission before rendering” and predict the outcome of one changed input from your independent fixture. State which host behavior still needs real verification.

This marks your personal practice record only. It is not a certification or an official workspace assessment.