Coordinate recovery manifests, eviction, and active handles — Review and demonstrate

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

Review the recovery ledger design

Recovery starts with a trusted description of completed work. A filename is not proof that bytes are complete, and a recovery ledger is not the data itself. Keep the live revision, prepared resources and committed resources distinct so a crash cannot turn an incomplete temporary output into a valid report.

Disposable host contract: report R at revision 12 owns input I and generated chunk C. A plain recovery ledger records expected chunk length, revision and status. Only a complete chunk with a committed ledger entry may be reopened as the report result. WTMP cleanup and recovery are conceptual; exact ledger persistence, checksum and atomic-commit APIs must be supplied by the host.

Supplied case: Review packet contains successful committed R but no interrupted, stale or missing-content fixture.

Worked reasoning: Add the 32/80 KiB prepared chunk, revision-12 artifact with live revision 13, and a missing committed chunk. These separately exercise completeness, freshness and availability. Preserve predicted state transitions as evidence to test with a real host later.

Contrast and diagnosis: Three copies of a healthy ledger do not establish crash recovery.

Worked reasoning and supplied artifact

// Disposable exercise fixture / host-contract notes; not executable API syntax.
// Supplied input: Review packet contains successful committed R but no interrupted, stale or missing-content fixture.
// Worked prediction: Add the 32/80 KiB prepared chunk, revision-12 artifact with live revision 13, and a missing committed chunk. These separately exercise completeness, freshness and availability. Preserve predicted state transitions as evidence to test with a real host later.
// Rejected alternative: Three copies of a healthy ledger do not establish crash recovery.

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.

Submit a state-transition table, three failure fixtures and the preservation rule for I. Identify which durable-write guarantees the host must document.

What to produce

Submit a state-transition table, three failure fixtures and the preservation rule for I. Identify which durable-write guarantees the host must document. 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.

• Review the recovery ledger design
• 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 “Review the recovery ledger design” 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.