What causes "failure while extracting content : %w" in yorukot/superfile?

Log pos and len(lines)/width at the call site to see which bound is violated

failure while extracting content : %w

Error message

failure while extracting content : %w

What it means

validateComponentPlacement extracts the region of rendered lines at the given component position and validates it. This error wraps a failure from m.extractComponent, meaning the requested region could not be cut out of the rendered lines. It typically indicates the computed component position (rows/cols) does not fit within the rendered content.

Source

Thrown at src/internal/validation.go:386

	// TODO: programatically ensure that only one of them is open at a time
	// We may need some sort of overlay model management
	if m.IsOverlayModelOpen() {
		finalRender := m.updateRenderForOverlay(mainRender)
		if err := validateRender(finalRender, m.fullHeight, m.fullWidth, false); err != nil {
			return fmt.Errorf("model rendering failures : %w", err)
		}

		// TODO: Add validations for overlay models
	}

	return nil
}

// Inclusive
func (m *model) validateComponentPlacement(lines []string, pos compPosition, border bool) error {
	extractedLines, err := m.extractComponent(lines, pos)
	if err != nil {
		return fmt.Errorf("failure while extracting content : %w", err)
	}

	cntRow := pos.endRow - pos.stRow + 1
	cntCol := pos.endCol - pos.stCol + 1
	extractedOut := strings.Join(extractedLines, "\n")
	if err := validateRender(extractedOut, cntRow, cntCol, border); err != nil {
		return fmt.Errorf("failure in extracted content : %w", err)
	}
	return nil
}

// Inclusive
func (m *model) extractComponent(lines []string, pos compPosition) ([]string, error) {
	if 0 > pos.stRow || pos.stRow > pos.endRow || pos.endRow >= len(lines) {
		return nil, fmt.Errorf("invalid row range [%v, %v], line count : %v",
			pos.stRow, pos.endRow, len(lines))
	}
	firstLineWidth := ansi.StringWidth(lines[0])

View on GitHub (pinned to b72f550bc6)

Solutions

Log pos and len(lines)/width at the call site to see which bound is violated
Clamp pos.stRow/stCol and endRow/endCol to the actual rendered dimensions before validating
Re-render the component and recompute its position after any terminal resize
Check whether the component output is empty or shorter than the allocated area

Example fix

// before
extractedLines, err := m.extractComponent(lines, pos)
// after
if pos.endRow >= len(lines) || pos.endCol >= ansi.StringWidth(lines[0]) {
	return fmt.Errorf("component position %v exceeds rendered area", pos)
}
extractedLines, err := m.extractComponent(lines, pos)

Defensive patterns

Strategy: validation

Validate before calling

func validPos(lines []string, pos compPosition) bool {
	return pos.stRow >= 0 && pos.stRow <= pos.endRow && pos.endRow < len(lines) &&
		pos.stCol >= 0 && pos.stCol <= pos.endCol && pos.endCol < ansi.StringWidth(lines[0])
}

Try / catch

if err := m.validateComponentPlacement(lines, pos, border); err != nil {
	log.Printf("placement failed at %v: %v", pos, err)
	return err // or re-render and retry once
}

Prevention

Recompute compPosition from freshly rendered content after any resize
Use ansi.StringWidth for all width math, never len()
Clamp positions to actual rendered dimensions before validation
Add unit tests for components rendered at minimum terminal size

When it happens

Trigger: validateFinalRender computes a compPosition whose stRow/endRow or stCol/endCol fall outside the rendered lines (e.g., component rendered smaller than expected), causing extractComponent to fail.

Common situations: Component renders fewer lines/columns than the model expects (terminal width changes, wrapping differences, ANSI-styled content narrower than assumed); off-by-one in position calculation.

Related errors

AI-assisted analysis of yorukot/superfile@b72f550bc6 (2026-09-01). Data as JSON: /api/errors/85d8a622efa862f9. Report an issue: GitHub.