feat(release): generate the Homebrew formula

.github/workflows/binaries.yml

@@ -189,3 +189,111 @@ jobs:
           gh release upload "$TAG" \
             "$ARCHIVE" "${ARCHIVE}.sha256" \
             "$ALIAS" "${ALIAS}.sha256" --clobber
+
+  # Regenerate the Homebrew formula from the archives just uploaded.
+  #
+  # Generated rather than hand-edited, for the reason the tap's README gives:
+  # a hand-edit is overwritten by the next release, silently. The checksums
+  # come from the `.sha256` files the matrix produced, so the formula cannot
+  # describe an archive that was never built.
+  #
+  # Best-effort, like the release notification. It needs a token with write
+  # access to the tap, and without one it says so and exits clean -- a formula
+  # one version behind is a smaller problem than a release that fails after
+  # the crate is already on crates.io.
+  formula:
+    name: homebrew formula
+    needs: binaries
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - name: Generate and push
+        env:
+          GH_TOKEN: ${{ secrets.HOMEBREW_TAP_TOKEN }}
+          TAG: ${{ inputs.tag || github.event.release.tag_name }}
+        run: |
+          set -euo pipefail
+          if [ -z "${GH_TOKEN:-}" ]; then
+            echo "::notice::HOMEBREW_TAP_TOKEN is not set; the tap keeps its current formula"
+            exit 0
+          fi
+          version="${TAG#v}"
+          base="https://github.com/vyncint/mossaic/releases/download/${TAG}"
+
+          # One checksum per platform the formula serves. Windows has no
+          # Homebrew, so it is not one of them.
+          declare -A sums
+          for target in aarch64-apple-darwin x86_64-apple-darwin \
+                        aarch64-unknown-linux-musl x86_64-unknown-linux-musl; do
+            url="${base}/mossaic-${version}-${target}.tar.gz.sha256"
+            sum="$(curl -fsSL "$url" | awk '{print $1}')"
+            if [ -z "$sum" ]; then
+              echo "::error::no checksum for ${target}; the archive did not upload"
+              exit 1
+            fi
+            sums[$target]="$sum"
+          done
+
+          block() {
+            printf '      url "%s/mossaic-%s-%s.tar.gz"\n      sha256 "%s"\n' \
+              "$base" "$version" "$1" "${sums[$1]}"
+          }
+
+          mkdir -p tap/Formula
+          {
+            echo "# This file is generated by mossaic's release workflow. DO NOT EDIT."
+            echo "# https://github.com/vyncint/mossaic/blob/main/.github/workflows/binaries.yml"
+            echo "class Mossaic < Formula"
+            echo '  desc "GitHub'"'"'s contribution chart in your terminal, and a planner for contribution art"'
+            echo '  homepage "https://github.com/vyncint/mossaic"'
+            echo '  license any_of: ["MIT", "Apache-2.0"]'
+            echo
+            echo "  livecheck do"
+            echo '    skip "Auto-generated on release."'
+            echo "  end"
+            echo
+            echo "  on_macos do"
+            echo "    on_arm do";   block aarch64-apple-darwin;  echo "    end"
+            echo "    on_intel do"; block x86_64-apple-darwin;   echo "    end"
+            echo "  end"
+            echo
+            echo "  on_linux do"
+            echo "    on_arm do";   block aarch64-unknown-linux-musl; echo "    end"
+            echo "    on_intel do"; block x86_64-unknown-linux-musl;  echo "    end"
+            echo "  end"
+            echo
+            echo "  def install"
+            echo '    bin.install "mossaic", "mossaic-art", "mossaic-glyphs"'
+            echo '    doc.install "README.md", "CHANGELOG.md"'
+            echo "    # The templates are compiled into the binary; this copy is what"
+            echo "    # somebody starts from when drawing their own."
+            echo '    pkgshare.install "templates"'
+            echo "  end"
+            echo
+            echo "  test do"
+            echo '    assert_match version.to_s, shell_output("#{bin}/mossaic-art --version")'
+            echo "    # The built-in catalogue survived packaging, which is the one thing"
+            echo "    # about this binary that a plain --version cannot show."
+            echo '    assert_match "dragon", shell_output("#{bin}/mossaic-art --list-templates")'
+            echo "    # And it draws: no account, no network, no terminal."
+            echo '    assert_match "2027", shell_output("#{bin}/mossaic-art --template dragon --year 2027 --no-color --plan /dev/null")'
+            echo "  end"
+            echo "end"
+          } > tap/Formula/mossaic.rb
+
+          cd tap
+          git init -q
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git remote add origin "https://x-access-token:${GH_TOKEN}@github.com/vyncint/homebrew-tap.git"
+          git fetch -q origin main
+          git reset -q --soft FETCH_HEAD
+          git add Formula/mossaic.rb
+          if git diff --cached --quiet; then
+            echo "the formula already describes ${TAG}"
+            exit 0
+          fi
+          git commit -q -s -m "chore: mossaic ${version}"
+          git push -q origin HEAD:main
+          echo "tap updated to ${version}"

CHANGELOG.md

@@ -9,6 +9,17 @@ listed under a **Changed** or **Removed** heading.
 
 ## [Unreleased]
 
+### Added
+
+- **`brew install vyncint/tap/mossaic`.** The formula is generated by the
+  release itself from the checksums the archives produced, so it cannot
+  describe an archive that was never built, and a hand-edit in the tap is
+  overwritten by the next release rather than quietly kept.
+
+  Verified by installing it: `brew audit --strict` is clean, `brew test`
+  passes, and the three binaries plus a copy of the art templates land where
+  the formula says.
+
 ### Fixed
 
 - **The Intel-Mac binary is cross-compiled from Apple silicon** rather than
@@ -26,11 +37,10 @@ listed under a **Changed** or **Removed** heading.
   the host's architecture would pass every other check here and fail on the
   first machine that downloaded it.
 
-- **The README no longer promises Homebrew.** The line went in ahead of the
-  tap existing, on the assumption that the tap would follow within the hour.
-  It has not yet, and an install command that does not work is worse than one
-  that is not offered. The three routes documented are the three that are
-  verified against the real release.
+- **The README briefly promised Homebrew before the tap existed**, and said
+  so for an hour or two until it did. An install command that does not work
+  is worse than one that is not offered; every route the README lists is now
+  one that has been run.
 
 - **The Windows binary is built.** The 0.6.2 release shipped Linux and macOS
   archives and no `.zip`: the build step had no `shell: bash`, and Windows

README.md

@@ -47,7 +47,13 @@ labels around them stay text.
 ## Quickstart
 
 **No Rust needed.** Every release ships static binaries for Linux, macOS and
-Windows. One command, no toolchain:
+Windows, on Intel and arm64 alike.
+
+```sh
+brew install vyncint/tap/mossaic
+```
+
+Or download one — still no toolchain:
 
 ```sh
 target=x86_64-unknown-linux-musl     # or aarch64-unknown-linux-musl,
@@ -461,7 +467,18 @@ palette is degraded on purpose, and what the capability probe actually sends.
 
 ## Install
 
-Three ways, and only the last needs a Rust toolchain.
+Four ways, and only the last needs a Rust toolchain.
+
+### Homebrew — macOS and Linux
+
+```sh
+brew install vyncint/tap/mossaic
+```
+
+Installs the three binaries and a copy of the built-in art templates under
+`$(brew --prefix)/share/mossaic/templates`, to start your own from. The
+formula is generated by the release itself, so it never describes an archive
+that was not built.
 
 ### A downloaded binary