[alandarev]

Summary

Build on #716 and #766 with 19 bounded tuning sliders grouped under the four existing Enhanced feature toggles, in both Legacy and Modern options.

• Checkbox changes on/off only; clicking the label/chevron expands controls. Groups start collapsed, with less common controls behind More settings.
• Show units, minimum/maximum, current value and Defaults/Custom/Not saved; provide individual/group/all resets.
• Apply choices live and save them once globally across maps/restart in [EnhancedTuning]. Untouched values inherit the shipped profile; player options never edit shared Look.json/LightMood.json.
• Preserve personal values through Classic, feature off/on and unavailable-renderer fallback. Keep developer session edits scoped and separate from player persistence.
• Tune shipped skill lights to 1× intensity, 1.5× radius, 4-cell radius cap and 1.4 overlap cap, based on native playtesting. Keep the public Classic default unchanged.
• Let grading strength reach zero independently of bloom.
• Correct the stale display-settings contract that still forbade the four feature choices already merged in Options window: game-standard tabs, per-feature Enhanced graphics, theme scrollbars #766; assert their load/save paths instead.

Related issues

Closes #774.
Related: #715, #716, #766.

Try it

1. Open Options → Graphics and enable Enhanced graphics.
2. Click Dynamic lights or its arrow: sliders expand without toggling the feature.
3. Adjust intensity/radius/cap while casting, then switch maps: the same personal choices remain active.
4. Turn the checkbox off and on: controls retain their values and expansion.
5. Reset one control or group to restore shipped Defaults; other preferences stay unchanged.
6. Try the other three feature groups and both bundled themes; Classic ignores all personal Enhanced tuning.

Changes by area

• Render/Look: control metadata, effective layering, scoped developer edits, preview/commit/reset lifecycle and accepted-feature gating.
• Data/GameConfig: sparse validated personal preferences, bounded invalid-key diagnostics and failure-preserving writes.
• UI/Options and RML/RCSS: four expandable groups, shared numeric rows, native pointer/keyboard integration and save feedback.
• Data/Render/Look.json: four reviewed skill-light defaults only; existing map overrides stay intact.
• Tests and documentation: descriptor bounds, inheritance/override/reset behavior, renderer refusal/recovery, per-frame mood coalescing, persistence failures, theme bindings and the Legacy screenshot.

No new dependency, top-level source layer, shader, packet or server feature.

Testing

• Head 2cf25f14d, incorporating upstream bdc21f3f7 with a clean history-preserving merge: Linux build and 945 tests passed, zero failures, one explicit GPU integration skip.
• Linux editor-enabled build and 991 tests passed, zero failures, one explicit GPU integration skip.
• Local upstream-equivalent quality checks passed: clang-format 21.1.8 and Cppcheck 2.13.0. Contribution scan found no private tooling names or credentials.
• Native QA verified expanded Legacy1024/Modern1024/Modern2560 readability, independent expansion/toggle behavior, focused keyboard adjustment without character movement, save failure with unchanged persisted bytes and visible Not saved, successful retry, restart, global Icarus persistence/reset, control/group/all reset isolation, and Classic/Enhanced retention. Runtime configuration was restored byte-identically and all QA clients exited. Graphics implementation is unchanged by the subsequent unrelated upstream merge.
• Descriptor bounds, persistence, inheritance/reset, renderer refusal/recovery and per-frame mood coalescing have regression coverage; reset/refusal ordering and the obsolete display-settings contract were mutation-tested.
• Final cross-platform CI is not green/complete. Initial fork preflight exposed an editor-enabled bundled-font test link failure on Linux/macOS/Windows. The test-only fix uses the same application glue as existing UI scaling tests and retains every assertion; both local build flavors pass. Fresh fork CI was started for this head, then cancellation was requested so this draft could be submitted without waiting. Fork verification PR #13, CI, Fork CI, editor matrix. This is explicitly a draft, not a merge-readiness claim.

Draft limits / remaining verification

This is not a claim of complete graphics acceptance: Legacy wide-layout coverage, full native endpoint/invalid-key/dependency/timing coverage, comparative graphics videos and Classic/UI pixel-identity evidence remain open. Legacy1024 and Modern1024/2560 expanded readability plus native restart/save-failure lifecycle were tested. Temporary developer $lightmood overrides are separate from the persisted player-strength row. Unsupported renderer effects retain preferences without applying them; recovery is attempted on the next feature/preset apply or restart.

Checklist

• I have read and followed docs/CODING_RULES.md.
• I have built the project locally.
• Changes are focused on one concern.
• Final cross-platform CI is green (incomplete; disclosed above).
• Remaining graphics acceptance is complete (kept open while this PR is a draft).

Written with AI assistance and tested by hand.