Version the exposed API manifest — Discover and trace

PART I

Warm-up

Reconnect with a useful idea before starting version the exposed api manifest. 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

Trace an unchanged v1 request on v2

A versioned API map records which names, signatures, semantics and capability requirements are promised to clients. The word manifest here means a plain review artifact: the source does not give an executable manifest schema. Version labels need compatibility cases, not just a changelog.

Exercise map v1 exposes preview(asset, width) with maximum width 1024 and local output only. Proposed v2 adds optional format while omission preserves v1 output. Remote output remains a separate capability. Old clients must keep working on v2 for previously valid requests.

Supplied case: Old client requests asset A, width 320, format omitted.

Worked reasoning: V2 must select the v1 default format and preserve the local output meaning. Adding an optional parameter is compatible only if omission retains the old behavior.

Contrast and diagnosis: Changing the omitted default to a new format can break old consumers despite an unchanged signature.

Worked reasoning and supplied artifact

// Disposable exercise fixture / host-contract notes; not executable API syntax.
// Supplied input: Old client requests asset A, width 320, format omitted.
// Worked prediction: V2 must select the v1 default format and preserve the local output meaning. Adding an optional parameter is compatible only if omission retains the old behavior.
// Rejected alternative: Changing the omitted default to a new format can break old consumers despite an unchanged signature.

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: Restricted automation extension. Build a small, understandable change around version the exposed api manifest.

Write old/new request rows for width 640 with format omitted and explicit new format.

What to produce

Write old/new request rows for width 640 with format omitted and explicit new format. 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.

• Trace an unchanged v1 request on v2
• 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 “Trace an unchanged v1 request on v2” 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.