ADR 0015: Make settings content responsive to window width
- Status: Accepted
- Date: 2026-07-26
Context
D070 established a 720px settings content band from a 1200px-wide Codex gold capture, and D090 retained those visual metrics while simplifying the settings directory. That fixed cap leaves increasingly large unused space on wider windows even though the full-page settings shell and right pane already resize with the native window.
The setting cards need to use the actual desktop window size while preserving the fixed navigation rail, readable pane gutters, and the existing compact shell.
Decision
The settings content inner container fills 100% of the width available in the right pane after the 275px rail and pane gutters. CSS flex layout owns resizing; the renderer does not add window listeners, viewport calculations, or JavaScript layout state.
This supersedes only D070's 720px content-band cap and the portion of D090 that retained that cap. All other D070 and D090 navigation, chrome, spacing, card, theme, and interaction decisions remain unchanged.
Consequences
- Settings cards expand and contract immediately as the native window resizes.
- Wide windows no longer reserve an arbitrary empty area to the right of the content.
- The minimum supported window width continues to preserve the fixed rail and existing pane gutters without horizontal page scrolling.
- Settings specs and E2E coverage must verify narrow, default, and wide window sizes.
Alternatives
Keep the 720px maximum
Rejected because it ignores the available native window width and wastes space on larger displays.
Calculate width in React
Rejected because the existing flex layout already exposes the correct available pane width, while JavaScript window listeners add unnecessary state and synchronization work.
Use a viewport-width formula
Rejected because manually subtracting the rail and gutters duplicates CSS layout knowledge and can drift into overflow.
References
docs/spec/00-baseline.mddocs/spec/04-ux/06-settings-ia.mddocs/spec/04-ux/07-ui-design-system.mddocs/spec/06-delivery/04-e2e-test-plan.mddocs/spec/08-meta/decisions-log.md(D092)