Generate Style Learn

You are the generate-style-learn skill — v3.5 Phase 3 of the doc-generation-pipeline. Extracts palettes from existing artifacts.

What this skill does

Analyzes 1+ artifact-files (PPT/DOCX/web/PDF) and extracts a reusable style palette to ~/.lintel/brand/palettes/<name>.json + companion ~/.lintel/brand/palettes/<name>-STYLE.md (human-readable).

Never modifies input-files. Read-only analysis.

Use case: operator gets a customer-brand-deck → wants to extract the palette + apply it to future generation-runs without manually curating tokens.

Per v3.5 design-doc Phase 3 (deferred from Phase 1 + Phase 2): style-learn is an optional add-on, body-shopped after Phase 1+2 were dogfooded. This is the completion-PR.

When to use

• "Customer sent a deck — extract their style so I match it in the next report" → /li:generate-style-learn deck1.pptx --name customer-A
• "Compare two style-references" → run the skill on each, diff palettes
• "Operator's own brand snapshot" → audit current ~/.lintel/brand/-palettes against ground-truth artifacts

When NOT to use

• Live style-edit — this is extraction, not an editor
• Single-color-pick — bin/li-doctor --brand-summary is faster for a one-off
• Customer-specific live-stream — this is batch

Inputs

• Required <paths> — 1+ artifact files (varierande format ok)
• Required --name <slug> — palette-name for output (e.g., customer-A or nordic-minimal)
• Optional --format <ppt|web|word|auto> — explicit format hint (default: auto-detect)
• Optional --overwrite — replace existing <name>.json if present
• Optional --out-dir <path> — palette output dir (default: ~/.lintel/brand/palettes/)

Extraction (per format)

PPT (.pptx):

• Open via python-pptx OR pptx-genjs
• Iterate theme colors → most-frequently-used fill/text colors
• Classify into primary/secondary/accent/text/background (60-30-10 rule)
• Extract heading font + body font + most-common sizes
• Layout distribution (% per layout type)
• Logo position from Slide Master
• Visual patterns (accent bars, animation style)

DOCX (.docx):

• Open via python-docx OR docx-templater
• Theme colors from docDefaults + styles.xml
• Font hierarchy (heading 1/2/3 + body)
• Margins + line-spacing
• Header/footer styles

Web (HTML/CSS):

• Parse + linked CSS
• Extract :root CSS variables (preferred source)
• Fall back: most-frequent computed colors in DOM
• Typography from font-family declarations

Auto-detect: file extension determines format

Output schema (palette JSON)

{
  "name": "nordic-minimal",
  "source_files": ["deck1.pptx", "deck2.pptx"],
  "extracted_at": "2026-05-28T18:00:00Z",
  "colors": {
    "primary": "#002855",
    "secondary": "#4A90D9",
    "accent": "#F2A900",
    "text_dark": "#1B1B1B",
    "text_light": "#FFFFFF",
    "background": "#FFFFFF"
  },
  "fonts": {
    "heading": "Segoe UI Semibold",
    "body": "Segoe UI Light",
    "heading_size_px": 32,
    "body_size_px": 13
  },
  "layout_distribution": {
    "content": 0.55,
    "section-header": 0.15,
    "title": 0.10,
    "two-column": 0.10,
    "data-viz": 0.10
  },
  "visual_patterns": {
    "logo_position": "top-right",
    "accent_bar": "left-edge-vertical",
    "bullet_style": "square",
    "animation": "fade"
  }
}

Output schema (companion STYLE.md)

Human-readable summary describing the style in plain language:

# <name> style

**Extracted from:** deck1.pptx, deck2.pptx (2026-05-28)

## Color story

Primary navy (#002855) with bright accent (#F2A900). High-contrast text-on-light.
60-30-10 ratio: navy dominant, blue secondary, gold accent.

## Typography

Segoe UI family across the board — Semibold for heading (32px), Light for body (13px).
Tight line-height, deliberate hierarchy.

## Layout pattern

Content-heavy (55%) with regular section-header punctuation (15%). Balanced
two-column + data-viz (10% each).

## Visual signature

Logo top-right, vertical accent bar left edge, square bullets, fade animations.

## Use this style

In future generation: `/li:generate ... --palette <name>`. Catalog at
~/.lintel/brand/palettes/<name>.json.

Workflow

Step 1 — Validate inputs

[ -z "$NAME" ] && { echo "Usage: /li:generate-style-learn <files> --name <slug>"; exit 2; }
for f in "$@"; do
  [ -f "$f" ] || { echo "Missing: $f"; exit 2; }
done

Step 2 — Per-file extraction

Detect format from extension. Apply format-specific extraction (per above section).

Step 3 — Aggregate across files

If multiple files: merge extractions:

• Colors: union of palettes; classify into 6 roles via 60-30-10
• Fonts: most-common heading + body
• Layout distribution: weighted average

Step 4 — Write outputs

mkdir -p "$OUT_DIR"
echo "$palette_json" > "$OUT_DIR/$NAME.json"
echo "$style_md" > "$OUT_DIR/$NAME-STYLE.md"

Step 5 — Surface confirmation

Style 'nordic-minimal' extracted.
  Source files: deck1.pptx, deck2.pptx
  Colors: 6 roles classified
  Fonts: 2 family (Segoe UI Semibold heading, Segoe UI Light body)
  Layout distribution: 5 categories
  Saved: ~/.lintel/brand/palettes/nordic-minimal.json
        ~/.lintel/brand/palettes/nordic-minimal-STYLE.md

To use: /li:generate ... --palette nordic-minimal

Status protocol

• DONE — palette + STYLE.md written, N source-files processed
• DONE_WITH_CONCERNS — written but extraction partial (e.g., logo-position unreliable)
• BLOCKED — source files unreadable OR no name provided OR write-permission denied
• NEEDS_CONTEXT — file format unsupported AND --format not specified

Pause-points

• --overwrite not set but palette name exists: hard-block for operator-confirm
• Multiple wildly-different styles in source files: surface "sources don't agree, palette will be averaged — proceed?"

Integration

Reads:

• Source artifact files (<paths>)

Writes:

• ~/.lintel/brand/palettes/<name>.json
• ~/.lintel/brand/palettes/<name>-STYLE.md

Consumed by:

• /li:generate --palette <name> (downstream format-builders)
• /li:generate-design --palette <name> (in shared pipeline)

Anti-patterns

• Modify source files — extraction is read-only.
• Inferred color-roles without justification — if the 60-30-10 ratio is unclear, surface the ambiguity + ask for operator-guidance rather than guessing.
• Overwrite without confirm — --overwrite flag required for replacement.

Failure recovery

• File format-detection fails: surface available formats + ask for a --format hint
• Aggregation conflict (multiple wildly-different styles): default to most-recent file's style + flag with warning
• Output dir not writable: fall back to ./palettes/<name>.json (current dir)

Recommended next steps after invocation

• Verify extraction quality: open <name>-STYLE.md + manually check claim-vs-source
• Test palette: /li:generate "test brief" --palette <name> → verify match
• For multi-source aggregation: re-run with --diff <existing-palette> to see what new sources added (future feature)