arc/canvas.md                               |   4 +
 crates/canvas/src/editor.rs                 |  28 ++++---
 crates/canvas/src/editor/evidence.rs        | 101 ++++++++++++++++++++++-
 crates/canvas/src/editor/format.rs          |  48 ++++++++---
 crates/canvas/tests/custom_tags.rs          |   9 +--
 crates/canvas/tests/structural_roundtrip.rs |  47 +++++++++--
 crates/canvas/tests/to_do_list.rs           | 137 +++++++++++++++++++++++++++++---
 crates/snowbound/src/tags.rs                |   9 +--
 8 files changed, 337 insertions(+), 46 deletions(-)