Sunburst diagram / year wheel for support function

[mrrudin]

Proposal

For overview / planning purposes I'd like a diagram to show a number of planned actions distributed over a yearwheel, i.e. a pie/sunburst diagram based on /grouped by calendar time spaces, like quarter, month, week, day.

It should be dynamic, based on today's date as base date for display, and nodes should be added based on a list of nodes with a corresponding CRON expression, to be able to calculate next occurrence over the coming year.

Use Cases

Display of planned activities, based on today's date to always be up-to-date.

Perfect for software maintenance support function, especially planned cloud upgrades etc.

Screenshots

Syntax

::: mermaid
 yearwheel;
baseDate now                                                          %% or constant like 2026-01-01

A("Verify yearwheel", "0 8 1 * 1")                             %% first monday every year
B("Finance upgrade", "0 0 22 ? 1,4,7,10 6#3")         %% every quarter, third saturday, at 22 hours
C("Maintenance upgrade", "0 12 * 3 *")                   %% every year in march

:::

Implementation

This is a proposal which I'd love to see built into mermaid by the wonderful community.

EDIT:

Additional thoughts on requirements:

• Quartz syntax for CRON expression is needed (crontab is not flexible enough).

Additional diagram configuration:

• Control display period by time unit and number of units depending on planning granularity.

mermaid
 yearwheel;
baseDate now                                                          %% now (dynamic) | constant like 2026-01-01
baseCalendarUnit year                                             %% year | quarter | month as time unit
baseCalendarInterval 1                                            %% no of time units to display, e.g. one year, two quarters, six months

A("Verify yearwheel", "0 8 1 * 1")                             %% first monday every year
B("Finance upgrade", "0 0 22 ? 1,4,7,10 6#3")         %% every quarter, third saturday, at 22 hours
C("Maintenance upgrade", "0 12 * 3 *")                   %% every year in march

[Shahir-47]

@knsv @sidharthv96 I’m interested in contributing to this and have opened a draft PR: #7459

In this draft, I implemented the grammar and parsing logic for yearwheel and added tests for both valid and invalid syntax. I’d appreciate your feedback before I proceed with the next step.

[knsv-bot]

[sisyphus-bot]

Thanks for the detailed proposal, @mrrudin! A yearwheel/sunburst diagram with CRON-based scheduling is an interesting concept.

This is a new diagram type request, which is architecturally significant — it requires a new Langium parser, DB, renderer, theme support, tests, and documentation. The dynamic date-based rendering (using baseDate now) would also be a novel pattern for Mermaid, since existing diagrams produce static output from static input.

We see that @Shahir-47 has already started work on a draft PR (#7459) with grammar and parsing logic — that is great initiative! A maintainer should weigh in on the overall design direction before further implementation work proceeds.

Flagging this for human review to assess feasibility, scope, and whether the dynamic date aspect aligns with Mermaid's rendering model.

[knsv]

I assume you can set the date to a fixed one as well?

[Shahir-47]

Yes you can!

[Shahir-47]

I wrote a couple of tests that are included in this PR that test both the fixed date and the now date

[dcuccia]

This is a great idea. Just went looking for a sunburst diagram myself and came up empty except for this SO question. Talking with Claude Opus 4.6, it seems the trickiest part is the renderer.

Architecturally, the rendering layer for yearwheel is essentially a sunburst chart with CRON-based angular mapping. Ideally the renderer could be built with a clean separation, so a generic sunburst could also be a possibility:

• Generic sunburst/arc layout (arcBuilder, polarLayout) — these primitives would also serve Pie & ring chart as an upgrade of pie chart #7325 (multi-level pie) and could eventually be extracted to rendering-util/ for broader reuse
• Yearwheel-specific CRON → angular position mapping

@Shahir-47 thoughts on this?

[dcuccia]

I'm not a Mermaid expert, just a happy consumer, so take all this with a grain of salt, but here are some possible concepts:

sunburst example

sunburst
    title Browser Market Share 2025

    "Chrome" : 65
        "Desktop" : 40
            "Windows" : 28
            "macOS" : 10
            "Linux" : 2
        "Mobile" : 25
            "Android" : 20
            "iOS" : 5
    "Safari" : 18
        "Desktop" : 6
        "Mobile" : 12
    "Firefox" : 8
        "Desktop" : 7
        "Mobile" : 1
    "Edge" : 5
    "Other" : 4

Output:

Possible shared architecture: