Coordinate recovery manifests, eviction, and active handles — Flash-check repair

PART I

Warm-up

Reconnect with a useful idea before starting coordinate recovery manifests, eviction, and active handles. 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

Repair double-counted reclaimed space

Eviction is a policy decision about replaceable resources. Start with ownership and retention promises, then compare the budget. Age or size can rank eligible victims, but must not make active or recovery-critical resources eligible by itself.

Exercise store budget is 100 MiB. A = 40 MiB active input, B = 30 MiB completed regenerable cache, C = 20 MiB committed recovery copy retained until export finishes. Current usage is 90 MiB. Eligibility and commit accounting are host requirements, not assumed WTMP methods or a hidden pin/unpin API.

Supplied case: Two concurrent requests D25 and E25 both inspect B30 and each assumes it may reclaim the entire 30.

Worked reasoning: A shared reservation decision must serialize or otherwise reconcile reclamation. Removing B once leaves 60; admitting both adds 50, reaching 110 and violating budget. Both independent local predictions cannot be committed.

Contrast and diagnosis: A victim is not two pools of free bytes merely because two workers saw it before either committed.

Worked reasoning and supplied artifact

// Disposable exercise fixture / host-contract notes; not executable API syntax.
// Supplied input: Two concurrent requests D25 and E25 both inspect B30 and each assumes it may reclaim the entire 30.
// Worked prediction: A shared reservation decision must serialize or otherwise reconcile reclamation. Removing B once leaves 60; admitting both adds 50, reaching 110 and violating budget. Both independent local predictions cannot be committed.
// Rejected alternative: A victim is not two pools of free bytes merely because two workers saw it before either committed.

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: Recovery rehearsal workspace. Build a small, understandable change around coordinate recovery manifests, eviction, and active handles.

Make a reservation ledger for D20 and E20. Calculate combined use after one eviction and identify an ordering where both fit.

What to produce

Make a reservation ledger for D20 and E20. Calculate combined use after one eviction and identify an ordering where both fit. 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 wuix.widget;
const button = widget.Button({
    text: "Continue",
    events: {
        click: fnc() -> void {
            navigator.open("dashboard");
        }
    }
});

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.

• Repair double-counted reclaimed space
• 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 “Repair double-counted reclaimed space” 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.