Defend version compatibility, capability policy, and migration decisions — Boundary detective

PART I

Warm-up

Reconnect with a useful idea before starting defend version compatibility, capability policy, and migration decisions. 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

Check revocation during prepared work

Permission migration changes who may perform an operation, not merely which names are visible. Keep the identity, operation, resource and decision together in every example. A new capability should be explicitly granted through the host policy; existing public API exposure cannot silently supply it.

Exercise policy: profile.read permits reading the caller’s own display name; profile.export is a separate grant for exporting the caller’s own profile. Version 1 clients have only profile.read. Version 2 adds export as an optional operation. The source does not define a manifest schema, so the artifacts here are plain policy tables, not executable permission syntax.

Supplied case: Mira’s export was prepared with grant revision 8. The grant is revoked at revision 9 before release of the artifact.

Worked reasoning: For this exercise, release requires a current authorization check. Preparation may have succeeded, but release at revision 9 must be refused and the prepared artifact kept inaccessible or cleaned by the host policy. Record those as different states.

Contrast and diagnosis: Checking permission only when a button is shown leaves a gap between the visible UI and the protected release operation.

Worked reasoning and supplied artifact

// Disposable exercise fixture / host-contract notes; not executable API syntax.
// Supplied input: Mira’s export was prepared with grant revision 8. The grant is revoked at revision 9 before release of the artifact.
// Worked prediction: For this exercise, release requires a current authorization check. Preparation may have succeeded, but release at revision 9 must be refused and the prepared artifact kept inaccessible or cleaned by the host policy. Record those as different states.
// Rejected alternative: Checking permission only when a button is shown leaves a gap between the visible UI and the protected release operation.

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: Extension compatibility portfolio. Build a small, understandable change around defend version compatibility, capability policy, and migration decisions.

Create a timeline with prepare, revoke and release. Then reverse revoke and release and state how the host serializes the decision.

What to produce

Create a timeline with prepare, revoke and release. Then reverse revoke and release and state how the host serializes the decision. 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.

• Check revocation during prepared work
• 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 “Check revocation during prepared work” 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.