Separate exposed API from capability permission — Boundary detective

PART I

Warm-up

Reconnect with a useful idea before starting separate exposed api from capability permission. 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

Keep nonexistent and denied targets externally safe

Visibility and permission answer different questions. Exposure decides whether a script can name a callable surface; capability permission decides whether this execution may use the requested resource. A successful import is evidence about naming, not evidence about access. A denial must remain a denial even when the script can name an alternative route to the same resource.

Host table: public-map exists and is allowed; staff-map exists and is denied; ghost-map is absent. Public error policy uses Destination unavailable for denied or absent resources.

Use a decision table with columns API visible, resource exists, capability grants, and allowed operation. Resource existence alone never changes a deny to allow. Keep public messages useful without disclosing protected paths, ownership, or records. Worked case: Internally, staff-map fails permission and ghost-map fails existence. Externally, both receive the same safe message. Internal diagnostics may distinguish them only within the host’s authorized logging policy.

Compare the tempting alternative: Showing “staff-map exists but belongs to a restricted team” discloses protected metadata even though navigation itself was blocked.

Worked reasoning and supplied artifact

// Paper trace / supplied exercise-host contract; no execution claimed.
// Host table: public-map exists and is allowed; staff-map exists and is denied; ghost-map is absent. Public error policy uses Destination unavailable for denied or absent resources.
// Internally, staff-map fails permission and ghost-map fails existence. Externally, both receive the same safe message. Internal diagnostics may distinguish them only within the host’s authorized logging policy.

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: Safe extension design. Build a small, understandable change around separate exposed api from capability permission.

Create internal and public result columns for all three targets, then add a target whose name contains private user information.

What to produce

A result matrix with deliberately limited public diagnostics.

• 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.

• Keep nonexistent and denied targets externally safe
• Create internal and public result columns for all three targets, then add a target whose name contains private user information.
• Separate source-backed behavior, host requirements and untested predictions.

One small recap task

Write a useful message that does not confirm protected existence.

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