mossaic

Make your GitHub contribution graph spell something. mossaic turns "2027 should read VYNCINT" into a number of commits for today, tells you each morning whether you are on pace, and says plainly when a year can no longer be drawn cleanly.

And it shows you the result: the whole year in your terminal, drawn as real rounded squares where the terminal can draw pixels, in GitHub's own Primer colours, with a tooltip that follows the mouse.

That is a real year, drawn in a real terminal. Every cell is an image: anti-aliased rounded squares at github.com's own geometry, sent over the kitty graphics protocol or sixel, lined up exactly with the character cells so the labels around them stay text.

Contents

Start here

• Quickstart — plan the art, track it, look at the graph
• Writing text into the graph — the whole guide: placement, what it costs, drawing on a background, saving a plan
• The GitHub Action — track on a schedule, into an issue, Slack, Discord or email

Reference

• Usage · Keys · Mouse · Known limits
• Why · How it works · Design notes
• Contributing · Security · Changelog

Quickstart

cargo install mossaic      # needs Rust 1.88+

Plan the art. No account and no network needed — this is arithmetic:

mossaic-art VYNCINT --year 2027            # what it looks like, and what it costs
mossaic-art VYNCINT --year 2027 --save     # remember the plan

Then, every morning:

gh auth login                              # once; mossaic never handles a token itself
mossaic-art --track                        # how far along, and what today owes

  letters     ██████████████████░░░░░░░░░░  50 of 75 bright
  owing       25 day(s) short, 100 contributions between them

  VYNCINT can still be drawn cleanly — 100 contributions to go.

  the rest of the year
    25 letter day(s) still to come, 100 contributions

(A year part-way through; yours will read differently. The full report, on a calendar you can reproduce exactly, is in docs/ART.md.)

It also answers the question no amount of committing fixes — whether days already inside the letters have spoiled them, and which placement would spoil the fewest.

And to look at the graph itself, whether or not you are drawing in it:

mossaic --demo             # a sample year: no account, no network
mossaic                    # yours

Press ? in it for the keys, the mouse, and — the question everything else depends on — what your terminal turned out to be able to draw.

That is the whole setup. Everything below is optional.

Two things decide it, and mossaic --capabilities tells you both:

terminal   TERM=xterm-kitty
kitty      yes          <- the protocol
sixel      no
cell       9x19 px      <- the size, needed to line an image up with the labels
background #0d1117  (Dark theme)
cells      kitty

• cells text means the terminal draws neither protocol. kitty, Ghostty, WezTerm, foot, Konsole, iTerm2, mlterm, Windows Terminal and xterm -ti vt340 all draw one of them; GNOME Terminal and Ptyxis draw neither, because VTE ships sixel switched off. Nothing is lost but the pixels — the chart still draws in block sextants.
• A window under 112 columns falls back too, and the chart says so under the legend rather than leaving you guessing.
• Either way, mossaic --png chart.png renders the same image to a file from any terminal at all.

Why

Your contribution graph is probably the chart you look at most often and have thought about least. It renders in someone else's tab, identically for everyone, and reports one thing, after the fact: whether you showed up.

mossaic turns it from a scoreboard into a canvas. Decide that 2027 should read VYNCINT and it works backwards — which days must be bright, at what shade, and, because every day's shade is relative to your busiest one, what that costs today. A year-long intention becomes a number you can act on this morning. Put it in Actions and it will tell you each day whether you are on pace, behind, or past the point where the word can still be finished.

Contribution art is usually done blind: generate thousands of commits, push, and find out. Here the year is arithmetic before it is commits — what it costs, where to place it so existing days do not punch holes in the letters, and whether it is still reachable in September.

And it draws the result honestly, so you can check the picture before making a single commit. GitHub's own Primer tokens, read from the stylesheets github.com serves. github.com's own geometry — an 11px square on a 14px pitch — kept as a ratio and scaled to whatever a character cell measures. Real anti-aliased squares over the kitty graphics protocol or sixel. Nothing is approximated for the terminal's convenience: when GitHub restyles the graph, a test in here is what should fail.

Moss is the metaphor and the mechanic: nothing happens on any one day, and after a season the wall is green.

Writing text into the graph

mossaic-art draws text as pixels on the calendar, emits the commits that would light it up, and tracks how far along you are — including the part no amount of committing fixes:

  VYNCINT cannot be drawn cleanly in 2026.
    61 day(s) inside the letters already have contributions, and
    nothing takes those away — the text would read with holes in it.
    --start-week 1 would leave 23 instead of 61.

mossaic-art VYNCINT --year 2027                 # what it would look like, and cost
mossaic-art VYNCINT --year 2027 --save          # remember the plan
mossaic-art --track                             # am I getting there?

Drawn that way the letters stand against an empty graph, which means not contributing on the other 290 days of the year. --background draws the background as a colour instead, so the art is one shade against another and every day of the year stays green:

mossaic-art VYNCINT --year 2027 --background 1  # letters on a field, not on nothing

GitHub's five shades are not evenly spaced, so mossaic measures the two you picked in CIELAB across all nine palettes GitHub ships and tells you what a reader will actually see — ΔE 35 at worst, clear. Leave two levels between them and it is legible everywhere; leave one and it is not.

The whole guide — placement, cost, saving the plan, and running the tracker on a schedule — is in docs/ART.md, and the Action that posts it to Slack, Discord or email is in action/README.md.

Usage

Three binaries, and every option has a default — the first line of each block is the whole command you need.

mossaic                          # you, this year
mossaic --demo                   # a sample year: no account, no network
mossaic octocat --year 2024      # someone else, some year
mossaic --file saved.json        # a saved calendar, no network

mossaic --capabilities           # what your terminal can draw
mossaic --png chart.png          # the chart as an image, from any terminal
mossaic --graphics sixel         # force a protocol, or `text` for no pixels
mossaic --cell 10x20             # when the terminal will not say how big a cell is
mossaic --theme light            # instead of following the terminal's background
mossaic --palette winter         # GitHub's own seasonal colours
mossaic --no-mouse               # leave mouse reporting alone

mossaic-art VYNCINT --year 2027  # draw text into a graph — see docs/ART.md
mossaic-art --track              # how far along the plan is
mossaic-art --track --today 2027-06-01   # what a day that has not arrived will owe
mossaic-art --backfill --repo ../art     # commit just what the plan is short
mossaic-glyphs                   # what this terminal makes of the fallback cells

From a checkout, cargo run -- … and cargo run --bin mossaic-art -- … are the same commands.

Keys

Mouse

Without a terminal that draws pixels

A terminal without either protocol loses the pixels and nothing else. The whole chart still draws, in block sextants — same layout, same colours, same tooltip:

┌ mossaic ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│vyncint  ·  2026  ·  9,527 contributions in 2026                                                                                                                              │
│                                                                                      ▐ 113 contributions on August 19th. ▌                                                   │
│    Jan            Feb         Mar            Apr         May            Jun         Jul         Aug    ▼       Sep         Oct         Nov            Dec                    │
│       🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛            │
│Mon    🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛            │
│       🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛            │
│Wed    🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛            │
│    🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛            │
│Fri 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛               │
│    🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛               │
│                                                                                                                                                                              │
│Wed, Aug 19 2026  ·  113 contributions                                                                                                                                        │
│Less 🬫🬛 🬫🬛 🬫🬛 🬫🬛 🬫🬛 More   ·   rounded cells                                                                                                                                  │
│110 active days  ·  longest 31  ·  best Aug 11 (146)                                                                                                                          │
│                                                                                                                                                                              │
│←→↑↓ day/week  ·  t today  ·  d cells  ·  m mouse off  ·  r reload  ·  q quit  ·  preview                                                                                     │
└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

How it works

Three things decide what you see, and the first is the only one you may need to act on:

• What your terminal can draw. mossaic asks it — one write, four questions, one round trip — rather than sniffing TERM, which is wrong in both directions: it misses terminals it has not heard of and claims support inside tmux or ssh where the escape never arrives. mossaic --capabilities prints the answers. --graphics and --cell override them.
• Which colours. Every value is a Primer token read out of the stylesheets github.com serves, not transcribed. Light or dark follows the terminal's own background over OSC 11, the way a browser follows the OS; --theme overrides it. GitHub swaps the greens for a few days a year and so does mossaic, on the same dates — --palette asks for them out of season.
• How a day is sized. A day is two character columns wide and one row tall, and the square inside it keeps github.com's own ratios — an 11px cell on a 14px pitch, rounded by 2px — scaled to whatever a character cell measures. That is what lets the month labels stay text while the cells are pixels.

docs/DESIGN.md is the long answer: what was traded for what, why the tooltip sits above the grid rather than over it, why the sixel palette is degraded on purpose, and what the capability probe actually sends.

Known limits

• VTE terminals have sixel switched off. GNOME Terminal and Ptyxis are built on VTE, which does implement sixel — but VTE_SIXEL_ENABLED_DEFAULT is false, the embedding application has to call vte_terminal_set_enable_sixel, and neither of them does. VTE has no kitty-graphics support at all. So those terminals answer no to both and get sextants, correctly. kitty, Ghostty, WezTerm, foot, Konsole, iTerm2, mlterm, Windows Terminal and xterm -ti vt340 all draw one protocol or the other.
• Multiplexers do not pass either graphics protocol through, so inside tmux or screen the probe comes back no and the chart falls to sextants. That is the right answer rather than a workaround: the escape would be swallowed either way.
• Motion reporting is not universal. Terminals that report clicks but not motion (Terminal.app among them) get click-to-select-a-day and no hover.
• Sixel has no alpha. Anti-aliased edges are composited against the background colour the terminal reported; where it reports none, GitHub's own canvas colour stands in, and on a terminal with a background image the corners will show a faint halo. Kitty, which takes an alpha channel, does not have the problem.
• The tooltip sits above the grid, not over the day. See above — it is the one placement both protocols can live with.
• Streaks are computed within the displayed year, so one spanning New Year is clipped at the year boundary.
• Pixel and square cells need about 112 columns, the bordered grid about 115×26. Below that Auto drops to a borderless style, where a future day and a day off the end of the year both look blank; d still forces the others if you would rather they clipped.
• Private contributions appear only if the authenticated user can see them.

Layout

Tests

cargo test                          # everything, no network
cargo test --lib                    # grid maths, colour, the encoders, the art font
cargo test --test smoke             # the real binary, in a real pty
cargo test -- --ignored             # the two that call the GitHub API

Two layers, because they catch different things: in-process tests check what is a function of its inputs, and the encoders are checked against the formats — the sixel is decoded back into pixels and compared to what the rasteriser drew. Out of process, [termlens] spawns the real binary in a real PTY.

What belongs in which layer, and the two mistakes that make tests flaky, is in CONTRIBUTING.md §3.

Contributing

Bug reports, terminal compatibility reports and PRs are welcome — see CONTRIBUTING.md for the dev setup and the testing policy, and docs/DESIGN.md before changing anything about the pixel path or the wait semantics the tests rely on.

A compatibility report is the single most useful thing an outside contributor can send, and it starts with two lines:

mossaic --capabilities     # what your terminal answered
mossaic --png /tmp/chart.png   # the same image, rendered to a file

Comparing the file with your screen separates "the rasteriser is wrong" from "the emission is wrong", which are different bugs.

Security reports: SECURITY.md.

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option — the Rust ecosystem's standard dual license. Apache-2.0 carries an express patent grant; MIT is maximally simple and GPLv2-compatible. Offering both lets every downstream user pick whichever their project or policy needs. Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.