diff --git a/.github/scripts/coverage_summary.py b/.github/scripts/coverage_summary.py
new file mode 100644
index 0000000..b8acfe3
--- /dev/null
+++ b/.github/scripts/coverage_summary.py
@@ -0,0 +1,110 @@
+"""Render a coverage.json report as a Markdown summary for a pull request comment.
+
+Usage: python coverage_summary.py coverage.json [--floor 90] [--label "..."]
+
+Writes Markdown to stdout. Keeps the table compact: files are listed worst-first so
+the rows that need attention are the ones you see, and fully covered files are folded
+into a single line rather than padding the table.
+"""
+
+import argparse
+import json
+import sys
+
+# The comment is located by this marker on later runs so it can be updated in place
+# rather than posting a new comment per push.
+MARKER = ""
+
+
+def bar(percent, width=20):
+ filled = round(percent / 100 * width)
+ return "█" * filled + "░" * (width - filled)
+
+
+def format_missing(missing, limit=6):
+ """Condense a list of line numbers into ranges, truncated for readability."""
+ if not missing:
+ return ""
+ ranges = []
+ start = previous = missing[0]
+ for line in missing[1:]:
+ if line == previous + 1:
+ previous = line
+ continue
+ ranges.append((start, previous))
+ start = previous = line
+ ranges.append((start, previous))
+
+ rendered = [str(a) if a == b else f"{a}–{b}" for a, b in ranges]
+ if len(rendered) > limit:
+ return ", ".join(rendered[:limit]) + f", +{len(rendered) - limit} more"
+ return ", ".join(rendered)
+
+
+def main():
+ parser = argparse.ArgumentParser()
+ parser.add_argument("report")
+ parser.add_argument("--floor", type=float, default=None)
+ parser.add_argument("--label", default="")
+ args = parser.parse_args()
+
+ with open(args.report) as handle:
+ data = json.load(handle)
+
+ totals = data["totals"]
+ percent = totals["percent_covered"]
+
+ out = [MARKER, "## Coverage report", ""]
+
+ if args.floor is not None:
+ met = percent >= args.floor
+ verdict = "meets" if met else "is below"
+ icon = "✅" if met else "❌"
+ out.append(f"{icon} **{percent:.2f}%** {verdict} the {args.floor:g}% floor.")
+ else:
+ out.append(f"**{percent:.2f}%** overall.")
+
+ out += [
+ "",
+ f"`{bar(percent)}` {totals['covered_lines']:,} / {totals['num_statements']:,} statements"
+ f" · {totals['missing_lines']:,} uncovered",
+ "",
+ ]
+
+ files = []
+ for path, entry in data["files"].items():
+ summary = entry["summary"]
+ if summary["num_statements"] == 0:
+ continue # empty __init__.py and friends carry no signal
+ files.append((path, summary, entry.get("missing_lines", [])))
+
+ partial = sorted(
+ (f for f in files if f[1]["percent_covered"] < 100),
+ key=lambda f: (f[1]["percent_covered"], -f[1]["missing_lines"]),
+ )
+ complete = [f for f in files if f[1]["percent_covered"] >= 100]
+
+ if partial:
+ out += [
+ "| File | Coverage | Missed | Uncovered lines |",
+ "| :--- | -------: | -----: | :-------------- |",
+ ]
+ for path, summary, missing in partial:
+ out.append(
+ f"| `{path}` | {summary['percent_covered']:.0f}% "
+ f"| {summary['missing_lines']} | {format_missing(missing)} |"
+ )
+ out.append("")
+
+ if complete:
+ names = ", ".join(f"`{path}`" for path, _, _ in sorted(complete))
+ out += [f"{len(complete)} file(s) at 100%
", "", names, "", "