Size change reporting (#10488)

* feat: add firmware size reporting and comparison scripts from #9860

* feat: add silence output feature to size_report and implement tests for size reporting scripts

* rm shame

* Fix baseline artifact paths in size report workflow

* feat: add firmware size reporting and comparison scripts from #9860

* feat: add silence output feature to size_report and implement tests for size reporting scripts

* rm shame

* Fix baseline artifact paths in size report workflow

* fix write permissions

* tunk

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Austin <vidplace7@gmail.com>

bin/size_report.py

@@ -0,0 +1,171 @@
+#!/usr/bin/env python3
+
+"""Compare firmware size reports and generate a markdown summary.
+
+Usage:
+    size_report.py <new_sizes.json> [--baseline <label>:<old_sizes.json>]...
+
+Examples:
+    # Compare PR against develop and master baselines
+    size_report.py pr.json --baseline develop:develop.json --baseline master:master.json
+
+    # Single baseline comparison
+    size_report.py pr.json --baseline develop:develop.json
+
+    # No baselines — shows sizes with blank delta columns
+    size_report.py pr.json
+"""
+
+import argparse
+import json
+import sys
+
+
+def load_sizes(path):
+    with open(path) as f:
+        return json.load(f)
+
+
+def format_delta(n):
+    """Format byte delta with sign and human-friendly suffix."""
+    sign = "+" if n > 0 else ""
+    if abs(n) >= 1024:
+        return f"{sign}{n:,} ({sign}{n / 1024:.1f} KB)"
+    return f"{sign}{n:,}"
+
+
+def generate_markdown(new_sizes, baselines, top_n=5):
+    """Generate a single table with current size and delta columns per baseline.
+
+    baselines: list of (label, old_sizes_dict), may be empty
+    """
+    labels = [label for label, _ in baselines]
+
+    # Build rows: (board, current_size, [(delta, abs_delta) per baseline])
+    rows = []
+    for board in sorted(new_sizes):
+        current = new_sizes[board]
+        deltas = []
+        for _, old_sizes in baselines:
+            old = old_sizes.get(board)
+            if old is not None:
+                d = current - old
+                deltas.append((d, abs(d)))
+            else:
+                deltas.append((None, 0))
+        # Sort key: max abs delta across baselines (biggest changes first)
+        max_abs = max((ad for _, ad in deltas), default=0)
+        rows.append((board, current, deltas, max_abs))
+
+    rows.sort(key=lambda r: r[3], reverse=True)
+
+    # Summary line
+    sections = []
+    summary_parts = [f"{len(new_sizes)} targets"]
+    for i, (label, old_sizes) in enumerate(baselines):
+        increases = sum(
+            1 for _, _, deltas, _ in rows if deltas[i][0] is not None and deltas[i][0] > 0
+        )
+        decreases = sum(
+            1 for _, _, deltas, _ in rows if deltas[i][0] is not None and deltas[i][0] < 0
+        )
+        net = sum(
+            deltas[i][0] for _, _, deltas, _ in rows if deltas[i][0] is not None
+        )
+        parts = []
+        if increases:
+            parts.append(f"{increases} increased")
+        if decreases:
+            parts.append(f"{decreases} decreased")
+        if parts:
+            parts.append(f"net {format_delta(net)}")
+            summary_parts.append(f"vs `{label}`: {', '.join(parts)}")
+        else:
+            summary_parts.append(f"vs `{label}`: no changes")
+
+    if not baselines:
+        summary_parts.append("no baseline available yet")
+
+    sections.append(f"**{' | '.join(summary_parts)}**\n")
+
+    # Table header
+    header = "| Target | Size |"
+    separator = "|--------|-----:|"
+    for label in labels:
+        header += f" vs `{label}` |"
+        separator += "----------:|"
+    sections.append(header)
+    sections.append(separator)
+
+    def format_row(board, current, deltas):
+        row = f"| `{board}` | {current:,} |"
+        for d, _ in deltas:
+            if d is None:
+                row += " |"
+            elif d == 0:
+                row += " 0 |"
+            else:
+                icon = "📈" if d > 0 else "📉"
+                row += f" {icon} {format_delta(d)} |"
+        return row
+
+    # Top N rows always visible
+    top = rows[:top_n]
+    for board, current, deltas, _ in top:
+        sections.append(format_row(board, current, deltas))
+
+    # Remaining rows in expandable section
+    rest = rows[top_n:]
+    if rest:
+        sections.append("")
+        sections.append(
+            f"<details><summary>Show {len(rest)} more target(s)</summary>\n"
+        )
+        sections.append(header)
+        sections.append(separator)
+        for board, current, deltas, _ in rest:
+            sections.append(format_row(board, current, deltas))
+        sections.append("\n</details>")
+
+    sections.append("")
+    return "\n".join(sections)
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Compare firmware size reports")
+    parser.add_argument("new_sizes", help="Path to new sizes JSON")
+    parser.add_argument(
+        "--baseline",
+        action="append",
+        default=[],
+        metavar="LABEL:PATH",
+        help="Baseline to compare against (e.g. develop:develop.json)",
+    )
+    parser.add_argument(
+        "--top",
+        type=int,
+        default=5,
+        help="Number of top changes to show before collapsing (default: 5)",
+    )
+    args = parser.parse_args()
+
+    new_sizes = load_sizes(args.new_sizes)
+
+    # Silence output when no targets were built — repo maintainer choice
+    if not new_sizes:
+        return
+
+    baselines = []
+    for b in args.baseline:
+        if ":" not in b:
+            print(f"Error: baseline must be LABEL:PATH, got '{b}'", file=sys.stderr)
+            sys.exit(1)
+        label, path = b.split(":", 1)
+        baselines.append((label, load_sizes(path)))
+
+    md = generate_markdown(new_sizes, baselines, top_n=args.top)
+    print(md)
+
+
+if __name__ == "__main__":
+    main()