history

T-Test plots gain truthful limits and an explicit view reset

id: LK-20260720-ttest-plot-viewport-and-density
date: 2026-07-20
sequence: 143
type: feat
compatibility: compatible
component: `labkit_TTestWizard_app` | `1.1.1 -> 1.2.0`
scope: Statistics Apps
scope: App Framework

Context

T-Test Wizard used the absolute data magnitude as a minimum padding span, so box plots with a narrow nonzero range could receive excessive empty space. Bar-chart zoom could move the zero baseline away from the y-axis edge, and the App had no visible action for returning to the fitted view. Two short status summaries also occupied detail-panel height.

Decision and rationale

Fit limits from the graphics that carry statistical meaning: distribution or bar extents, optional observations, standard-deviation error bars, and significance brackets. Keep zero at the appropriate edge for one-sided bar data because truncated bar baselines distort magnitude; mixed-sign data must instead show zero inside the axis. Keep box plots distribution-fitted.

Expose an App-owned reset action backed by the framework's general transient plot-view revision. Use the framework's line-count hint for short summaries rather than adding T-Test-specific pixel sizes.

Changes

• Corrected the fitted span and padding used by bar, box, and annotation geometry.
• Kept zero at the lower or upper y-limit for positive or negative bar plots across programmatic, toolbar, and wheel-driven limit changes.
• Added Reset plot view without recalculating tests or changing project data.
• Refined box fill, outlines, whiskers, observation overlays, bar opacity, error-bar caps, and outward ticks.
• Reduced What will run and Result family to two-line summary panels with the framework's summary reading size.

User and data impact

Project schema 2, completed comparison values, CSV outputs, formulas, and test choices are unchanged. T-Test Wizard 1.2.0 requires labkit.app 1.2 or later for compact summaries and one-shot plot viewport revisions. Existing projects open without migration.

Compatibility and migration

No additional migration applies beyond the compatibility information in the preceding impact section.

Validation

• The T-Test hidden-GUI workflow checks fitted limits, zero-edge persistence, box-plot independence, compact summary sizing, and explicit view reset.
• Framework contract tests cover plot viewport preservation and revision resets.
• Documentation rendering and history consistency cover the versioned change.

Evidence

The validation details above are the supporting evidence for this record.

Known limitations and follow-up

Developer-led visual review should compare box, bar, error-bar, and bracket appearance at typical desktop sizes and with real scientific label lengths.