gantt

ProgressionTimelineSeries

Gantt chart — task bars across a date axis.

Use for project plans with overlapping or staggered tasks. Each task is a bar on the time axis; bars can span multiple periods and carry status tints.

swimlaneplanningmilestonesagile

When to use

Overlapping work across lanes. When tasks run in parallel across multiple workstreams and the audience needs to see who is busy when. The lane-stacked bars make concurrency visible at a glance.
Span is the story. Each bar's length encodes its duration. Use gantt when start dates, end dates, and overlap are what you want the audience to remember.
Status pills add a second channel. Tint bars with done / live / at-risk / blocked to layer health onto schedule. The plan reads as both 'when' and 'how it's going' in one chart. Since the bars carry no status text, a swatch+label status key is emitted automatically below the chart for the statuses present.

When not to use

Single workstream. One lane of bars is a timeline, not a gantt. Use timeline or list-steps when there is no parallel work to coordinate.
More than five lanes. Past five workstreams the bars compress and the labels crowd. Group lanes (collapse 'SDK' subdomains into 'SDK') or split into two slides.
No spans at all. A gantt mixes bars with the odd milestone — but if every task is a point-in-time event with no durations, use timeline or roadmap milestones. gantt earns its chrome only when bars carry meaningful length.

Common mistakes

Writing the detail prose as a trailing inline-code token instead of a nested bullet. Detail must be a nested bullet ONE level deeper than the task, not a trailing ` code ` token — only a nested bullet drives the reveal popover and speaker note; a trailing-token 'detail' isn't recognized at all.

Authoring

<!-- _class: gantt -->

`2026 Q1 .. 2026 Q4` `today Q3`

## What ships in each phase, by workstream.

- First workstream
  - First task `Q1..Q2` `done`
  - Second task `Q2..Q3` `live` `after: First task`
  - Milestone `Q4` `milestone` `after: Second task`
- Second workstream
  - First task `Q1..Q2` `done`
  - Second task `Q2..Q3`

Slots

Slot	Selector	Required	Description
`title`	`h2`	yes	Slide heading naming the plan.
`tasks`	`ul > li`	yes	Outer li per workstream lane; nested bullets per task. Each task carries trailing inline-code tokens, in any order: a span `START..END` (a bar) or a single time point (a milestone diamond); an optional status; an optional `after: Task name` dependency; an optional `milestone` keyword. `..` is the only span delimiter. Time points are ISO dates (2026-03-15), quarters (Q1 or 2026 Q1), or months (Jan); a chart uses dates OR ordinals, not both. Status vocabulary: on-track / done / live / at-risk / warn / blocked / fail / deferred / pilot / decision. The axis derives from the data; the eyebrow may override it with a `START..END` window and add a `today <point>` marker. Tokens are validated by the linter (retired delimiter, bad span/status, dangling or inverted `after:`).
`detail`	`ul > li > ul > li > ul > li`	no	Optional per-task reveal detail. A nested bullet under a TASK (one level deeper than the task) — plain prose: the owner, the blocker, the why — is captured as that task's detail rather than rendered on the bar. It drives two surfaces from one source: (1) on screen (Drawing Board present/practice/preview) the bar/milestone is tagged data-mark and the prose rides an inert `<template class="chart-detail">` the reveal layer shows in a popover on hover/tap, with the active bar lifted + glowing and the rest dimmed (gantt is reveal-only — no 3D tilt, which would skew the time axis); (2) the static PDF — the same detail folds into the slide's speaker note (`Task (span): item · item`) as a Marp-faithful comment. Renders nothing on the chart face, so a chart with no detail bullets is byte-identical. Must be a bullet, not a trailing inline-code token.

Data shape

A chart uses dates OR ordinals (quarters/months) consistently — never mix 2026-03-15 spans with Q1/Jan spans in the same chart.
.. is the only span delimiter — a hyphen or en-dash between two dates isn't recognized as a span.
after: Task name must reference another task's exact (case-insensitive) label AND that task must itself carry a parseable time span — a task with only status pills and no START..END/point is never indexed, so after: pointing at it is flagged dangling even though the label is on the slide and visibly rendered. Source order doesn't matter otherwise: a forward reference to a spanned task defined later is fine.

Anatomy

┌─────────────────────────────────────────┐
│  header                                 │
│  Gantt chart heading.                   │
│                                         │
│  Task A         ▓▓▓▓▓▓▓▓▓▓▓▓▓▓░░░░░░    │
│  Task B         ▓▓▓▓▓▓▓▓░░░░░░░░░░░░    │
│  Task C         ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓░░    │
│  Task D         ▓▓▓▓▓▓░░░░░░░░░░░░░░    │
│                                         │
│  footer                           1/19  │
└─────────────────────────────────────────┘

roadmapphased grid of deliverables across workstreams without continuous spans
kanbancurrent state by stage rather than schedule by lane
list-stepssequential process with descriptive steps, no parallel lanes