Create a dark, intimate painterly self-portrait in the style of an old master sketchbook study: {argument name="subject" default="a middle-aged woman artist"} seated at a worn wooden table, leaning forward toward the viewer with a calm, searching, slightly tired expression, warm brown eyes, loose dark curly hair gathered messily back, and a rumpled charcoal-gray linen shirt with rolled sleeves. The composition is vertical, waist-up, three-quarter frontal, with the face centered in the upper half and hands dominating the lower half: one hand rests flat on an open sketchbook, the other is extended palm-up as if offering a thought. Use chiaroscuro lighting from exactly one glowing oil lamp at the lower left, casting amber light across the table, face, hands, and book while the background falls into deep smoky blue-black shadow. Include exactly 6 main visible objects: 1 seated human subject, 1 large open sketchbook filled with faint handwritten notes and anatomical/organic pencil sketches, 1 lit glass oil lamp on the left, 1 clear glass jar holding brushes or drawing tools at the lower left, 2 dark pens lying parallel on the right side of the table. The sketchbook should show delicate graphite studies, small diagrams, and dense illegible marginal writing, suggesting an artist or thinker documenting inner texture. Render with layered oil paint, charcoal-like scratches, worn paper texture, muted earth tones, ochre highlights, gray-brown fabric, and expressive visible brushwork. Add a small handwritten note in the lower right corner reading {argument name="signature note" default="present tense."}. Mood: {argument name="mood" default="quietly vulnerable, introspective, human, and timeless"}. Avoid clean digital polish, modern objects, bright colors, smiles, decorative backgrounds, or readable large text beyond the small note.