Refactor ratchet coverage action

.github/actions/ratchet-coverage/action.yml

@@ -33,7 +33,7 @@ runs:
         restore-keys: |
           ${{ runner.os }}-llvmcov-
     - name: Install cargo-llvm-cov
-      run: cargo install cargo-llvm-cov
+      run: uv run --script scripts/ratchet_coverage/install_cargo_llvm_cov.py
       shell: bash
     - if: runner.os == 'Windows'
       name: Install bc (MSYS2)
@@ -43,40 +43,12 @@ runs:
         path-type: inherit
     - name: Run coverage
       id: cov
-      run: |
-        set -euo pipefail
-        output=$(cargo llvm-cov --summary-only ${{ inputs.args }})
-        echo "$output"
-        percent=$(echo "$output" | grep -oEm1 '[0-9]+(\.[0-9]+)?%' | tr -d '%')
-        echo "percent=$percent" >> "$GITHUB_OUTPUT"
+      run: uv run --script scripts/ratchet_coverage/run_coverage.py
       shell: bash
     - name: Ratchet coverage
-      run: |
-        set -euo pipefail
-        file="${{ inputs.baseline-file }}"
-        current="${{ steps.cov.outputs.percent }}"
-        baseline=0
-        if [ -f "$file" ]; then
-          baseline=$(cat "$file")
-        fi
-        echo "Current coverage: $current%"
-        echo "Baseline coverage: $baseline%"
-
-        if ! echo "$current" | grep -Eq '^[0-9]+(\.[0-9]+)?$'; then
-          echo "Invalid coverage value: $current" >&2
-          exit 1
-        fi
-        if ! echo "$baseline" | grep -Eq '^[0-9]+(\.[0-9]+)?$'; then
-          baseline=0
-        fi
-
-        if (( $(bc -l <<<"$current < $baseline") )); then
-          echo "Coverage decreased" >&2
-          exit 1
-        fi
-
-        mkdir -p "$(dirname "$file")"
-        printf '%.2f' "$current" > "$file"
+      run: uv run --script scripts/ratchet_coverage/ratchet_coverage.py
+      env:
+        CURRENT_PERCENT: ${{ steps.cov.outputs.percent }}
       shell: bash
     - name: Save baseline
       if: success()

scripts/ratchet_coverage/install_cargo_llvm_cov.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env -S uv run --script
+# /// script
+# requires-python = ">=3.12"
+# dependencies = ["plumbum", "typer"]
+# ///
+from plumbum.cmd import cargo
+import typer
+
+
+def main() -> None:
+    try:
+        cargo["install", "cargo-llvm-cov"]()
+        typer.echo("cargo-llvm-cov installed successfully")
+    except Exception as e:
+        typer.echo(f"Failed to install cargo-llvm-cov: {e}", err=True)
+        raise typer.Exit(code=1)
+
+
+if __name__ == "__main__":
+    typer.run(main)

scripts/ratchet_coverage/ratchet_coverage.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env -S uv run --script
+# /// script
+# requires-python = ">=3.12"
+# dependencies = ["plumbum", "typer"]
+# ///
+from pathlib import Path
+import typer
+
+
+def read_baseline(file: Path) -> float:
+    """Return the stored baseline coverage or 0.0 if missing/invalid."""
+    if file.is_file():
+        try:
+            return float(file.read_text().strip())
+        except ValueError:
+            return 0.0
+    return 0.0
+
+
+def main(
+    baseline_file: Path = typer.Option(
+        Path(".coverage-baseline"), envvar="INPUT_BASELINE_FILE"
+    ),
+    current: float = typer.Option(..., envvar="CURRENT_PERCENT"),
+) -> None:
+    baseline = read_baseline(baseline_file)
+
+    typer.echo(f"Current coverage: {current}%")
+    typer.echo(f"Baseline coverage: {baseline}%")
+
+    if current < baseline:
+        typer.echo("Coverage decreased", err=True)
+        raise typer.Exit(code=1)
+
+    baseline_file.parent.mkdir(parents=True, exist_ok=True)
+    baseline_file.write_text(f"{current:.2f}")
+
+
+if __name__ == "__main__":
+    typer.run(main)

scripts/ratchet_coverage/run_coverage.py

@@ -0,0 +1,36 @@
+#!/usr/bin/env -S uv run --script
+# /// script
+# requires-python = ">=3.12"
+# dependencies = ["plumbum", "typer"]
+# ///
+from pathlib import Path
+import re
+import shlex
+import typer
+from plumbum.cmd import cargo
+
+
+def extract_percent(output: str) -> str:
+    match = re.search(r"([0-9]+(?:\.[0-9]+)?)%", output)
+    if not match:
+        typer.echo("Could not parse coverage percent", err=True)
+        raise typer.Exit(code=1)
+    return match[1]
+
+
+def main(
+    args: str = typer.Option("", envvar="INPUT_ARGS"),
+    github_output: Path = typer.Option(..., envvar="GITHUB_OUTPUT"),
+) -> None:
+    cmd = cargo["llvm-cov", "--summary-only"]
+    if args:
+        cmd = cmd[shlex.split(args)]
+    output = cmd()
+    typer.echo(output)
+    percent = extract_percent(output)
+    with github_output.open("a") as fh:
+        fh.write(f"percent={percent}\n")
+
+
+if __name__ == "__main__":
+    typer.run(main)