[lostmartian]

What

agentdiff --card creates an image of your spend that you can post:

• Output: writes agentdiff-card.html (change with --card-out) and opens it in the browser (--no-open to skip).
• Sizes: landscape 1200×675 for X and LinkedIn, or portrait 1080×1350 for the LinkedIn feed, both exported at 2x.
• Options: dark or light theme, and Hide $ to show percentages only.
• Export: Download PNG and Copy image buttons.
• Report footer: the terminal report now ends with Share it: agentdiff --card ….

Why

This is roadmap P1.3, built-in reach. The launch depends on people posting their own numbers, and an image is what gets shared on LinkedIn and X.

How

• sessions/card.py:
  • card_data() builds aggregate-only data: total, avoidable, a four-way breakdown, the top three leak categories, session and project counts, and the period;
  • build_card_html() embeds that data as JSON, escaping </ so it can't close the script tag. A test covers this.
• The page draws the card on a <canvas>, using Manrope and JetBrains Mono from Google Fonts with system-font fallbacks. It redraws once the fonts load and exports with canvas.toBlob.
• No new Python dependencies: no Pillow and no bundled fonts. Brand assets for launch posts stay in the separate marketing repo.
• Privacy: the card never includes session titles, project names, file paths or commands. A test plants identifiable strings in a session and asserts none of them reach the HTML.

Testing

make lint                  -> All checks passed
uv run python -m pytest    -> 466 passed (5 new in tests/test_card.py)

Rendered from my real logs in a browser:

• landscape, portrait, Hide $ and light theme all render without overlaps;
• the landscape export is a 2400×1350 PNG of about 240 KB;
• the brand fonts load;
• no console errors;
• the generated HTML contains none of my session or project names.

Checklist

• Exactly one logical change in this PR
• make lint passes
• uv run python -m pytest is green
• Docs updated if user-facing
• CHANGELOG.md entry added under [Unreleased] (if feat/fix)
• Conventional title: type(scope): summary

[lostmartian]

Closing: the shareable card isn't going into the product. Marketing assets live outside this repo.