show each commit's diffstat in the listing

README.md

@@ -1,9 +1,10 @@
 # post-range-diff-comment
 
 Posts `git range-diff` of a force push to a pull request as a collapsed
-comment: an aligned listing of the commit pairs, then one collapsible
-interdiff per rewritten commit. GitHub's "Compare" link diffs the two trees;
-this shows how the commits changed.
+comment: an aligned listing of the commit pairs, each commit followed by its
+lines added, lines removed and files changed (`+3 -1 2f`), then one
+collapsible interdiff per rewritten commit. GitHub's "Compare" link diffs the
+two trees; this shows how the commits changed.
 
 ```yaml
 on:

post-range-diff-comment.sh

@@ -82,6 +82,9 @@ if [[ -n ${CREATION_FACTOR:-} ]]; then
   args+=("--creation-factor=$CREATION_FACTOR")
 fi
 git -c core.abbrev=40 range-diff "${args[@]}" "$old_range" "$new_range" >"$WORK/range-diff.txt"
+for range in "$old_range" "$new_range"; do
+  git log --format=%H --numstat "$range"
+done >"$WORK/stats.txt"
 
 PUSHED_AT="$(date -u +%Y-%m-%dT%H:%M:%SZ)"
 short() { git rev-parse --short "$1"; }
@@ -94,6 +97,7 @@ render() {
     --old-range "$pretty_old" --new-range "$pretty_new" \
     --old-base "$old_base" --new-base "$new_base" \
     --base-behind "$base_behind" --base-ahead "$base_ahead" \
+    --stats "$WORK/stats.txt" \
     --pushed-at "$PUSHED_AT" --max-bytes "$1" <"$WORK/range-diff.txt"
 }
 render "${MAX_COMMENT_BYTES:-65000}" >"$WORK/comment.md"

render.py

@@ -7,8 +7,10 @@
 import html
 import re
 import sys
+from collections.abc import Callable
 from dataclasses import dataclass, replace
 from datetime import datetime, timezone
+from pathlib import Path
 
 # Pair numbers are right-aligned to the width of the longer range, so a header
 # starts with at most a few spaces.  Interdiff lines are indented by exactly
@@ -35,6 +37,13 @@ class Pair:
     body: tuple[str, ...] = ()
 
 
+@dataclass
+class Stat:
+    added: int = 0
+    removed: int = 0
+    files: int = 0
+
+
 def main(argv: list[str]) -> int:
     ap = argparse.ArgumentParser(description=__doc__)
     ap.add_argument(
@@ -72,6 +81,12 @@ def main(argv: list[str]) -> int:
         required=True,
         help="commits in the new base missing from the old one",
     )
+    ap.add_argument(
+        "--stats",
+        type=Path,
+        required=True,
+        help="`git log --format=%%H --numstat` of both ranges",
+    )
     ap.add_argument(
         "--max-bytes",
         type=int,
@@ -96,6 +111,7 @@ def main(argv: list[str]) -> int:
             new_base=args.new_base,
             base_behind=args.base_behind,
             base_ahead=args.base_ahead,
+            stats=parse_stats(args.stats.read_text()),
             max_bytes=args.max_bytes,
             pushed_at=args.pushed_at,
         )
@@ -132,6 +148,21 @@ def parse(text: str) -> list[Pair]:
     ]
 
 
+def parse_stats(text: str) -> dict[str, Stat]:
+    stats: dict[str, Stat] = {}
+    for line in text.splitlines():
+        if "\t" not in line:
+            if line:
+                stat = stats[line] = Stat()
+            continue
+        # numstat prints "-" for the line counts of a binary file.
+        added, removed, _path = line.split("\t", 2)
+        stat.added += int(added.replace("-", "0"))
+        stat.removed += int(removed.replace("-", "0"))
+        stat.files += 1
+    return stats
+
+
 def render(
     pairs: list[Pair],
     *,
@@ -146,6 +177,7 @@ def render(
     new_base: str,
     base_behind: int,
     base_ahead: int,
+    stats: dict[str, Stat],
 ) -> str:
     counts = {op: sum(1 for p in pairs if p.op == op) for op in OP_LABEL}
     tally = (
@@ -173,7 +205,7 @@ def assemble(pairs: list[Pair], truncated: bool) -> str:
         parts = (
             head
             + (["", note] if truncated else [])
-            + ["", render_listing(pairs, repo_url)]
+            + ["", render_listing(pairs, repo_url, stats)]
             + (
                 ["", render_interdiffs(pairs)]
                 if any(p.op == "!" for p in pairs)
@@ -198,16 +230,33 @@ def assemble(pairs: list[Pair], truncated: bool) -> str:
     return out
 
 
-def render_listing(pairs: list[Pair], repo_url: str) -> str:
+def render_listing(pairs: list[Pair], repo_url: str, stats: dict[str, Stat]) -> str:
     width = number_width(pairs)
+    stat = stat_column(pairs, stats)
     lines = [
-        f"{p.lnum.rjust(width)}:  {sha_html(p.lsha, repo_url)} {p.op} "
-        f"{p.rnum.rjust(width)}:  {sha_html(p.rsha, repo_url)} {html.escape(p.subject)}"
+        f"{p.lnum.rjust(width)}:  {sha_html(p.lsha, repo_url)}{stat(p.lsha)} {p.op} "
+        f"{p.rnum.rjust(width)}:  {sha_html(p.rsha, repo_url)}{stat(p.rsha)} {html.escape(p.subject)}"
         for p in pairs
     ]
     return "<pre>\n" + "\n".join(lines) + "\n</pre>"
 
 
+def stat_column(pairs: list[Pair], stats: dict[str, Stat]) -> Callable[[str], str]:
+    cells = {
+        sha: (f"+{s.added}", f"-{s.removed}", f"{s.files}f")
+        for p in pairs
+        for sha in (p.lsha, p.rsha)
+        if (s := stats.get(sha))
+    }
+    widths = [max(map(len, column)) for column in zip(*cells.values())]
+
+    def column(sha: str) -> str:
+        cell = cells.get(sha, [""] * len(widths))
+        return "".join(f" {part:>{width}}" for part, width in zip(cell, widths))
+
+    return column
+
+
 def render_interdiffs(pairs: list[Pair]) -> str:
     width = number_width(pairs)
     blocks = []

tests/fixtures/basic.md

@@ -5,10 +5,10 @@
 <sup>reproduce: <code>git range-diff 9b127fb^..deecb4b 9b127fb^..031a726</code></sup>
 
 <pre>
-1:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/9b127fbefa8c868ee2aec33496f658793715ea4b">9b127fbefa</a> = 1:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/9b127fbefa8c868ee2aec33496f658793715ea4b">9b127fbefa</a> add b
-2:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/521d6e7130970908efb2c4370c589d194041d6ad">521d6e7130</a> ! 2:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/9914d9036bfa9513e1e505143e051833500db892">9914d9036b</a> tweak a, add c
-3:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/deecb4b7a41ec39b40cdfc935ab28eb769c3aead">deecb4b7a4</a> < -:  ---------- add d
--:  ---------- > 3:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/031a72677e2ee12123ab2c8ef794bc3d0c521d8b">031a72677e</a> add e
+1:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/9b127fbefa8c868ee2aec33496f658793715ea4b">9b127fbefa</a> +1 -0 1f = 1:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/9b127fbefa8c868ee2aec33496f658793715ea4b">9b127fbefa</a> +1 -0 1f add b
+2:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/521d6e7130970908efb2c4370c589d194041d6ad">521d6e7130</a> +3 -1 2f ! 2:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/9914d9036bfa9513e1e505143e051833500db892">9914d9036b</a> +3 -1 2f tweak a, add c
+3:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/deecb4b7a41ec39b40cdfc935ab28eb769c3aead">deecb4b7a4</a> +1 -0 1f < -:  ----------          add d
+-:  ----------          > 3:  <a href="https://github.com/fungi-protocol/post-range-diff-comment/commit/031a72677e2ee12123ab2c8ef794bc3d0c521d8b">031a72677e</a> +1 -0 1f add e
 </pre>
 
 <details>

tests/fixtures/basic.numstat

@@ -0,0 +1,20 @@
+deecb4b7a41ec39b40cdfc935ab28eb769c3aead
+
+1	0	d
+521d6e7130970908efb2c4370c589d194041d6ad
+
+2	1	a
+1	0	c
+9b127fbefa8c868ee2aec33496f658793715ea4b
+
+1	0	b
+031a72677e2ee12123ab2c8ef794bc3d0c521d8b
+
+1	0	e
+9914d9036bfa9513e1e505143e051833500db892
+
+2	1	a
+1	0	c
+9b127fbefa8c868ee2aec33496f658793715ea4b
+
+1	0	b

tests/test_action.py

@@ -107,7 +107,9 @@ def run_action(
         return result.stdout
 
     def test_force_push_full_checkout(self):
-        self.assertIn("; 1 commit; same base <a", self.run_action())
+        out = self.run_action()
+        self.assertIn("; 1 commit; same base <a", out)
+        self.assertIn("</a> +1 -1 1f < -:", out)
 
     def test_rebase_onto_newer_base(self):
         self.git("checkout", "-q", "main")

tests/test_render.py

@@ -28,6 +28,7 @@ def render_basic(max_bytes=65000):
         new_base=NEW_BASE,
         base_behind=0,
         base_ahead=12,
+        stats=render.parse_stats((FIXTURES / "basic.numstat").read_text()),
     )
 
 
@@ -58,11 +59,27 @@ def test_body_line_that_looks_like_a_header_stays_a_body(self):
 class RenderTest(unittest.TestCase):
     def test_listing_is_one_aligned_pre_block(self):
         pairs = render.parse("1:  aaaa = 1:  aaaa first\n10:  bbbb < -:  ---- tenth\n")
-        out = render.render_listing(pairs, REPO)
+        out = render.render_listing(pairs, REPO, {})
         self.assertEqual(out.count("<pre>"), 1)
         self.assertIn("\n 1:  <a", out)
         self.assertIn("\n10:  <a", out)
 
+    def test_stats_are_summed_per_commit(self):
+        stats = render.parse_stats(
+            "aaaa\n\n3\t1\ta\n-\t-\ta => b\nbbbb\ncccc\n\n0\t12\tc\n"
+        )
+        self.assertEqual(stats["aaaa"], render.Stat(added=3, removed=1, files=2))
+        self.assertEqual(stats["bbbb"], render.Stat())
+        self.assertEqual(stats["cccc"], render.Stat(removed=12, files=1))
+
+    def test_listing_aligns_stats(self):
+        pairs = render.parse("1:  aaaa ! 1:  bbbb one\n2:  cccc < -:  ---- two\n")
+        stats = {"aaaa": render.Stat(5, 0, 1), "bbbb": render.Stat(120, 7, 10)}
+        first, second = render.render_listing(pairs, REPO, stats).splitlines()[1:3]
+        self.assertIn("aaaa</a>   +5 -0  1f ! 1:", first)
+        self.assertIn("bbbb</a> +120 -7 10f one", first)
+        self.assertIn("cccc</a>             < -:  ----------             two", second)
+
     def test_relative_time(self):
         self.assertEqual(
             render.relative_time("2026-09-17T00:10:17Z"),
@@ -89,7 +106,7 @@ def base(new, behind, ahead):
 
     def test_subject_is_escaped(self):
         pairs = render.parse("1:  aaaa = 1:  aaaa <script>&\n")
-        out = render.render_listing(pairs, REPO)
+        out = render.render_listing(pairs, REPO, {})
         self.assertIn("&lt;script&gt;&amp;", out)
         self.assertNotIn("<script>", out)