[vyncint]

Release v0.9.0: the ease-of-use release from the 2026-10-30 review (milestone 0.9.0, #124–#147).

Why 0.9.0, not 0.8.2. docs/RELEASING.md counts "a changed CLI flag" as breaking before 1.0, and this release changes three:

• --png - now means stdout.
• Runtime failures exit 1, while usage errors keep 2.
• mossaic-art --write refuses a dirty tree, a HEAD other than main, and future-dated commits without --future.

The library also changes github::whoami to return Result<String, NoUser>. All of this is recorded under Changed or Fixed.

Headline fixes

• --write no longer resets an existing repository's branch and destroys its work (mossaic-art --write into an existing repository resets its branch and loses work #124).
• The release semver check runs for the first time (The release semver check has never run: crates.io answers the probe with 403 #144). It used to get a 403 and skip on every release.
• The Action's example workflow is valid (The Action's example workflow is not valid, and its other recipes trip users up #145).
• A bare mossaic says why gh couldn't name you (A bare mossaic blames sign-in for every gh failure, and gh's errors arrive garbled #133).
• Late terminal replies are no longer read as keystrokes (Terminal replies that arrive after the 250 ms probe are read as keystrokes #140).
• An unknown background no longer gives unreadable text on a light terminal (An unknown terminal background makes the chart text unreadable on light terminals and Windows #141).
• --today decides the year and the palette (--today doesn't decide the year or the palette, so --png output depends on the day it runs #136).
• New --cells option (Cell styles: no --cells option, and forced pixels in a narrow window draw nothing #142).

Checklist (docs/RELEASING.md)

• Cargo.toml is 0.9.0 and Cargo.lock is refreshed.
• The CHANGELOG has [0.9.0] - 2026-10-30, a fresh [Unreleased], and both link definitions. extract-changelog.sh 0.9.0 prints the section (234 lines), and its selftest passes.
• Every action@v0.8.1 ref and every "pin a number" example now says 0.9.0, across the Action README, action.yml, the example workflow and ART.md. Historical mentions are left as they were.
• cargo test --all-features, run without COLORTERM as CI does: 299 passed. actionlint is clean.
• Stress on the merged commit before tagging.

Signed-off-by: Vyncint Ng 115854244+vyncint@users.noreply.github.com