From 4ef847ce30a2a8ca9b23b59f796f12065b815270 Mon Sep 17 00:00:00 2001
From: "Claude (agent-stats)" <el-github@elangley.org>
Date: Thu, 24 Sep 2026 23:07:25 -0700
Subject: [PATCH] test(tooling): the repo-stats suite tells a sparse model from
 a padded one, and --out refuses a foreign CSV (improvise-1xfb.5.1)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze
---
 scripts/repo-stats         |  6 ++++++
 scripts/repo-stats-test.sh | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/scripts/repo-stats b/scripts/repo-stats
index b89577c4..6444d2a8 100755
--- a/scripts/repo-stats
+++ b/scripts/repo-stats
@@ -302,6 +302,12 @@ def main():
     ap.add_argument("-C", dest="repo", default=".", help="the repository (default .)")
     a = ap.parse_args()
     os.makedirs(a.out, exist_ok=True)
+    ours = {f"{n}.csv" for n in ["churn"] + ANALYSES}
+    foreign = sorted(f for f in os.listdir(a.out) if f.lower().endswith(".csv") and f not in ours)
+    if foreign:
+        print(f"repo-stats: {a.out} holds CSVs this script did not write, and "
+              f"`improvise import` would merge them: {', '.join(foreign)}", file=sys.stderr)
+        return 2
     try:
         r = report(a.repo, a.ref, a.since, a.min_revs, os.path.abspath(a.out))
     except ImproviseFailed as e:
diff --git a/scripts/repo-stats-test.sh b/scripts/repo-stats-test.sh
index 5a7378b7..2e138dbd 100755
--- a/scripts/repo-stats-test.sh
+++ b/scripts/repo-stats-test.sh
@@ -170,8 +170,26 @@ if run "$work/stats" text; then
   views="$(grep -c '^## View: ' "$work/stats/repo-stats.improv")"
   [ "$views" = 10 ] && ok "the model keeps a view per file and the report's four" \
     || bad "the model keeps a view per file and the report's four" "$views views"
+  # Sparse, not padded: a padded merge has the same numbers and views, but a
+  # `-` item in every category and per-file views seated on the padding.
+  dashes="$(grep -c '|-|' "$work/stats/repo-stats.improv")"
+  [ "$dashes" = 0 ] && ok "the sparse model has no padding item" \
+    || bad "the sparse model has no padding item" "$dashes lines name |-|"
+  churn_view="$(awk '/^## View: churn$/,/^$/' "$work/stats/repo-stats.improv")"
+  for seat in "date: row" "agent-rules: none" "coupled: none" "crosses-crate: none"; do
+    grep -qx -- "$seat" <<< "$churn_view" && ok "the churn view seats $seat" \
+      || bad "the churn view seats $seat" "$(tr '\n' ' ' <<< "$churn_view")"
+  done
 fi
 
+# An --out holding a CSV this script did not write is refused, since the folder
+# import would merge it. The script's own CSVs, from a rerun, are not foreign.
+mkdir -p "$work/foreign"; echo "x,y" > "$work/foreign/other.csv"
+"$STATS" -C "$repo" --since 2026-06-01 --out "$work/foreign" > /dev/null 2>&1
+got=$?
+[ "$got" = 2 ] && ok "a foreign CSV in --out is refused with exit 2" \
+  || bad "a foreign CSV in --out is refused with exit 2" "exit $got"
+
 # The window is scoped to the ref: at the tag, the shrink has not happened.
 if run "$work/at-tag" json --ref before-shrink; then
   row "--ref scopes the log" by-area "web and harness" '["11","0","0.000"]'