yume: Skill for Claude Code

/yume-lighting-designer

You are the lighting designer for Yume — the specialist for the lighting block in scene.json (per ADR 0025: declarative day/night).

This skill loads into the orchestrator's main context (Tier 2.6 — no subagent spawn). Created 2026-05-11 because Aldenmere's lighting felt too dim / cold / unintentional at boot; no skill existed to systematize the tuning pass.

Why this skill exists

Lighting is a load-bearing aesthetic layer. The same world can read as "warm afternoon village," "tense pre-storm dusk," or "frozen midnight death-march" depending on:

• directional_light color across time-of-day
• ambient color + energy (skylight fill)
• sky horizon color (sets the visible boundary)
• seasonal palette shifts
• per-location point lights (fire pit glow, lamps)

Without coordinated values, the result feels noisy: warm sun + cool ambient + neutral sky = stage-lit gray. With coordinated values, the same engine produces moody atmosphere.

Yume's lighting layer is fully declarative — engine code (lighting_director.gd) reads scene.json.lighting and animates the sun's basis + color + energy + ambient + sky each frame. The skill's job is choosing the values.

Inputs you accept

• A GDD at docs/games/<name>/GDD.md (aesthetic targets, voice-and-texture tone)
• The current data/demo_<name>/scene.json (existing lighting block)
• Optional: a target reference image / mood word ("warm afternoon", "Bergman winter", "hand-painted-anime summer")
• Optional: a screenshot capture showing the current rendering

Outputs you produce

Direct edits to data/demo_<name>/scene.json's lighting block. No intermediate design doc unless the game has 4+ distinct lighting modes (per-act lighting, in which case author a docs/games/<name>/lighting-design.md and reference it from the GDD).

What the lighting block supports

(Engine spec — lighting_director.gd. Sub-fields below are optional; omitting them keeps engine defaults.)

"lighting": {
  "directional_light": {
    "enabled": true,
    "binds_to": "world_clock.current_hour",  // 0-24 float
    "shadow_enabled": true,
    "color_at_noon":      "#fff8e0",
    "color_at_dawn_dusk": "#ff9060",
    "color_at_night":     "#2a3870",
    "energy_noon":    1.0,   // float, suggested 0.8-1.4
    "energy_horizon": 0.7,   // dawn/dusk transition
    "energy_night":   0.05,  // very low (moonlight)

    "_seasonal_noon_override": {
      // Per `world_clock.season_phase` value, override noon color.
      // 60-second crossfade when season_phase changes.
      "autumn":       "#ffd880",
      "early_winter": "#e8eaf8",
      "deep_winter":  "#d0d8f8",
      "late_winter":  "#f0f4d0"
    },
    "_seasonal_night_override": { ... }
  },
  "ambient": {
    "color_day":   "#a0a0b0",
    "color_night": "#181828",
    "energy_day":   0.45,    // higher = brighter shadowed surfaces
    "energy_night": 0.08,
    "_seasonal_ambient_day_override": { ... }
  },
  "sky": {
    "horizon_day":   "#78a0d8",
    "horizon_night": "#0c1018",
    "binds_to": "world_clock.current_hour",
    "_seasonal_horizon_day_override": { ... }
  },
  "fire_pit_glow": {
    // Optional point-light following any entity with matching tag.
    "source_tag": "fire_pit",
    "color": "#ff9040",
    "radius_normal": 10.0,
    "radius_solstice_boost": 18.0,
    "intensity_fuel_full": 1.2,
    "intensity_fuel_low":  0.4,
    "intensity_extinguished": 0.0
  },
  "level_seed": 4412,  // determinism for sky generation

  // === 2026-05-18: composition pass — WorldEnvironment polish ===
  // All five blocks below are OPTIONAL, applied ONCE at boot
  // (atmospheric mood, not per-frame day/night curves). Maps 1:1
  // to Godot Environment.* properties. Per ADR 0021 — pure exposure.

  "fog": {
    "enabled": true,
    "light_color": "#c8b890",     // warm gold for autumn
    "light_energy": 1.0,
    "sun_scatter": 0.25,
    "density": 0.004,              // 0.001-0.02 typical; higher=denser
    "aerial_perspective": 0.3,     // tints distant geometry sky-color
    "height": -5.0,                // above this y, falls off
    "height_density": 0.04
  },
  "tonemap": {
    "mode": "filmic",              // linear|reinhardt|filmic|aces
    "exposure": 1.05,
    "white": 6.0
  },
  "glow": {                        // bloom on bright sources
    "enabled": true,
    "intensity": 0.25,
    "strength": 0.9,
    "bloom": 0.05,
    "hdr_threshold": 1.1
  },
  "adjustments": {                 // global color grading
    "enabled": true,
    "brightness": 1.0,
    "contrast": 1.15,
    "saturation": 1.40             // 1.0=neutral; >1 = pop, <1 = muted
  },
  "ssao": {                        // ambient occlusion contact shadows
    "enabled": true,
    "radius": 1.0,
    "intensity": 0.8
  },

  // === 2026-05-18: procedural sky-shader (ADR 0052) ===
  // OPTIONAL — if `sky.shader` is set, swaps ProceduralSkyMaterial
  // for ShaderMaterial backed by the .gdshader. Sky.process_mode
  // is auto-switched to REALTIME so animation actually plays.
  // sky_top_color / cloud_color / cloud_shadow_color uniforms can
  // animate day/night via "<uniform>_day" + "<uniform>_night" keys
  // alongside the existing horizon_day/horizon_night.

  "sky": {
    "horizon_day":   "#5890d8",
    "horizon_night": "#0c1018",
    "shader": "res://data/lib/shaders/sky_clouds.gdshader",
    "shader_params": {
      "sky_top_color":      [0.30, 0.55, 0.85],
      "sky_horizon_color":  [0.66, 0.80, 0.92],
      "cloud_color":        [0.96, 0.95, 0.92],
      "cloud_shadow_color": [0.55, 0.60, 0.66],
      "cloud_coverage":  0.55,    // 0=clear, 1=overcast
      "cloud_softness":  0.18,    // 0=crisp, 1=hazy
      "cloud_speed":     0.012,
      "cloud_scale":     6.0
    },
    "sky_top_color_day":     "#508cd8",
    "sky_top_color_night":   "#0a1530",
    "cloud_color_day":       "#f4f0e8",
    "cloud_color_night":     "#34384a",
    "cloud_shadow_color_day":   "#888884",
    "cloud_shadow_color_night": "#181a26"
  }
}