fix(tooling): repo-stats survives a window of empty commits, and the fixture covers renames, the root crate and a refused script (improvise-1xfb.5.1)

churn.csv now has a fixed header. When no file changed in the window,
no model is built and the report says so. docs/*.md, README.md and
RELEASING.md count as prose, and .codex/ as agent docs. The suite no
longer builds improvise itself, because checkers.sh scrubs the linker's
environment.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze

scripts/repo-stats

@@ -25,14 +25,15 @@ AREAS = [
     ("context/code", re.compile(r"^context/code/")),
     ("context/test-evidence", re.compile(r"^context/test-evidence/")),
     ("other context", re.compile(r"^context/")),
-    ("agent docs and skills", re.compile(r"^(AGENTS\.md|CLAUDE\.md|\.agents/|\.claude/)")),
+    ("other docs", re.compile(r"^(docs/.*\.md|README\.md|RELEASING\.md)$")),
+    ("agent docs and skills", re.compile(r"^(AGENTS\.md|CLAUDE\.md|\.agents/|\.claude/|\.codex/)")),
     ("scripts/CI", re.compile(r"^(scripts/|\.github/|nix/|flake\.nix$)")),
     ("web and harness", re.compile(r"^(web|harness)/")),
     ("rust tests", re.compile(r"(^|/)(tests|benches)/.*\.rs$|(^|/|_)tests?\.rs$")),
     ("rust src", re.compile(r"\.(rs|pest)$")),
 ]
 OTHER = "other"
-PROSE = {"context/code", "context/test-evidence", "other context", "repo-map",
+PROSE = {"context/code", "context/test-evidence", "other context", "other docs", "repo-map",
          "agent docs and skills"}
 CODE = {"rust src", "rust tests", "scripts/CI", "web and harness"}
 AGENT_RULES = "agent docs and skills"
@@ -42,6 +43,7 @@ AGENT_RULES = "agent docs and skills"
 ANALYSES = ["coupling", "abs-churn", "age", "soc"]
 CATEGORIES = ["commit", "date", "week", "entity", "area", "kind", "coupled",
               "crosses-crate", "agent-rules"]
+CHURN_HEADER = ["commit", "date", "week", "entity", "area", "kind", "added", "deleted"]
 MEASURES = ["added", "deleted", "commits", "degree", "average-revs", "age-months", "soc"]
 TABLES = ["by-area", "by-kind", "area-by-week", "by-day"]
 HERE = os.path.dirname(os.path.abspath(__file__))
@@ -146,10 +148,8 @@ def flag_coupling(path):
                      "agent-rules"], rows)
 
 
-def build_dir(out, log, min_revs, today):
+def build_dir(out, log, rows, min_revs, today):
     """The directory improvise imports: churn.csv and one CSV per analysis."""
-    rows = churn_rows(log)
-    write_csv(os.path.join(out, "churn.csv"), list(rows[0]), rows)
     with tempfile.NamedTemporaryFile("w", suffix=".log", delete=False) as f:
         f.write(log + "\n")
     try:
@@ -263,8 +263,11 @@ def report(repo, ref, since, min_revs, out):
     today = git(repo, "show", "-s", "--date=short", "--format=%cd", sha).strip()
     r = {"ref": name, "sha": sha, "since": since, "commits": commits, "out": out,
          "docs": doc_sizes(repo, sha), "tables": {}, "coupling": [], "soc": [], "age": []}
-    if commits:
+    rows = churn_rows(log)
-        build_dir(out, log, min_revs, today)
+    write_csv(os.path.join(out, "churn.csv"), CHURN_HEADER, rows)
+    # Empty commits alone change no file: nothing to analyse, so no model is built.
+    if rows:
+        build_dir(out, log, rows, min_revs, today)
         r["tables"] = run_improvise(out)
         for a in ("coupling", "soc", "age"):
             r[a] = read_csv(os.path.join(out, f"{a}.csv"))
@@ -290,6 +293,8 @@ TITLES = {
 def text(r, top):
     out = [f"repo-stats: {r['ref']} ({r['sha'][:10]}), since {r['since']}, "
            f"{r['commits']} non-merge commits"]
+    if not r["tables"]:
+        out += ["", "No file changed in the window, so no model was built."]
     for t in TABLES:
         if r["tables"].get(t):
             out += ["", TITLES[t]] + table(r["tables"][t])

scripts/repo-stats-test.sh

@@ -13,12 +13,15 @@ pass=0; fail=0
 ok()  { printf '  ok   %s\n' "$1"; pass=$((pass+1)); }
 bad() { printf '  FAIL %s (%s)\n' "$1" "$2"; fail=$((fail+1)); }
 
-# The improvise under test: on PATH in CI (`nix shell .#improvise`), else this tree's.
+# The improvise under test: on PATH in CI, else this tree's debug build. No build
+# here: checkers.sh scrubs the linker's environment (context/code/tooling.md §7).
 if command -v improvise >/dev/null; then
   IMPROVISE="$(command -v improvise)"
-else
+elif [ -x "$here/../target/debug/improvise" ]; then
-  cargo build --quiet --manifest-path "$here/../Cargo.toml" --bin improvise || exit 1
   IMPROVISE="$here/../target/debug/improvise"
+else
+  echo "repo-stats-test: no improvise; run \`cargo build --bin improvise\` first" >&2
+  exit 1
 fi
 export IMPROVISE
 
@@ -57,13 +60,14 @@ git init -q -b main "$repo"
 # Before the window: must count nowhere.
 put README.md 50 old; commit 2026-01-01
 
-# Two commits co-change five files, so each pair couples at 100% over 2 revs.
+# Two commits co-change six files, so each pair couples at 100% over 2 revs.
+# src/ is the root crate's, so it crosses a boundary with both crates/.
 for f in crates/a/src/lib.rs crates/b/src/lib.rs; do put "$f" 10 x1; done
-put crates/a/tests/t.rs 4 x1
+put src/main.rs 5 x1; put crates/a/tests/t.rs 4 x1
 put AGENTS.md 3 x1; put .agents/skills/wave/agent-rules.md 3 x1
 commit 2026-06-02
 for f in crates/a/src/lib.rs crates/b/src/lib.rs; do put "$f" 6 x2; done
-put crates/a/tests/t.rs 4 x2
+put src/main.rs 5 x2; put crates/a/tests/t.rs 4 x2
 put AGENTS.md 3 x2; put .agents/skills/wave/agent-rules.md 3 x2
 commit 2026-06-03
 
@@ -93,6 +97,8 @@ put scripts/foo.sh 7 x3; put .github/workflows/ci.yml 1 x3
 put web/app.js 9 x3; put harness/x.js 2 x3
 put Cargo.lock 11 x3
 put crates/a/src/grammar.pest 3 x3
+put .beads/issues.jsonl 2 x3; put site/index.html 1 x3
+put docs/guide.md 2 x3; put .codex/config.toml 1 x3
 commit 2026-06-04
 g tag before-shrink
 
@@ -103,8 +109,11 @@ g checkout -q main
 GIT_AUTHOR_DATE=2026-06-06T12:00:00Z GIT_COMMITTER_DATE=2026-06-06T12:00:00Z \
   g merge -q --no-ff -m merge side
 
-# A shrink in the next ISO week, so one area deletes and one row spans two weeks.
+# A shrink in the next ISO week, so one area deletes and one row spans two weeks,
-put web/app.js 3 x4; commit 2026-06-09
+# and a rename, which --no-renames counts as a delete and an add.
+put web/app.js 3 x4
+g mv scripts/foo.sh scripts/bar.sh
+commit 2026-06-09
 
 # $1 output dir, $2 "text" to also write the text report, rest: extra args.
 run() {
@@ -121,34 +130,37 @@ run() {
 if run "$work/stats" text; then
   is "no gh/main in the fixture, so the ref is HEAD" '.ref' '"HEAD"'
   is "the merge commit is not counted, the side commit is" '.commits' '5'
-  row "rust src is .rs and .pest outside tests" by-area "rust src" '["35","20","0.571"]'
+  row "rust src is .rs and .pest outside tests" by-area "rust src" '["45","25","0.556"]'
   row "rust tests are the tests/ files" by-area "rust tests" '["8","4","0.500"]'
-  row "agent docs and skills" by-area "agent docs and skills" '["12","6","0.500"]'
+  row "agent docs and skills take .codex" by-area "agent docs and skills" '["13","6","0.462"]'
+  row "docs/*.md is other docs" by-area "other docs" '["2","0","0.000"]'
   row "context/code" by-area "context/code" '["8","0","0.000"]'
   row "context/test-evidence" by-area "context/test-evidence" '["5","0","0.000"]'
   row "repo-map is its own area" by-area "repo-map" '["13","0","0.000"]'
   row "other context" by-area "other context" '["2","0","0.000"]'
   row "kb.pl" by-area "kb.pl" '["5","0","0.000"]'
-  row "scripts/CI takes .github" by-area "scripts/CI" '["8","0","0.000"]'
+  row "scripts/CI takes .github, and a rename is a delete and an add" \
+      by-area "scripts/CI" '["15","7","0.467"]'
   row "web and harness, and its deletion ratio" by-area "web and harness" '["14","9","0.643"]'
-  row "a lock file is generated" by-area "generated" '["11","0","0.000"]'
+  row "a lock file, .beads/ and site/ are generated" by-area "generated" '["14","0","0.000"]'
   row "the pre-window README counts nowhere" by-area "other" '["4","0","0.000"]'
-  row "prose is the context areas and agent docs" by-kind prose '["40","6","0.150"]'
+  row "prose is the context areas, other docs and agent docs" by-kind prose '["43","6","0.140"]'
-  row "code is rust, scripts/CI and web" by-kind code '["65","33","0.508"]'
+  row "code is rust, scripts/CI and web" by-kind code '["82","45","0.549"]'
-  row "prose to code is prose over code" by-kind ProseToCode '["0.615","0.182",""]'
+  row "prose to code is prose over code" by-kind ProseToCode '["0.524","0.133",""]'
   is "weeks are columns, first-seen first" '.tables["area-by-week"][0][1:]' '["2026-W24","2026-W23"]'
   row "an area is split by ISO week" area-by-week "web and harness" '["3","11"]'
   is "every day's churn.csv total equals code-maat's abs-churn" \
      '[.tables["by-day"][1:][]|.[1]==.[2]]|all' 'true'
-  row "a day's total is every file changed that day" by-day 2026-06-04 '["66","66"]'
+  row "a day's total is every file changed that day" by-day 2026-06-04 '["72","72"]'
   is "gotchas end with their section" '.docs.repo_map.gotchas' '3'
   is "the longest gotcha is measured over its lines" \
      '.docs.repo_map.longest|[.number,.lines]' '[2,2]'
   is "test-evidence entries are ### and #### headings" '.docs.test_evidence.entries' '3'
-  is "coupling finds the ten co-changed pairs" '.coupling|length' '10'
+  is "coupling finds the 15 pairs of six files, and web/app.js with scripts/foo.sh" \
-  is "two crates' files cross a crate boundary" \
+     '.coupling|length' '16'
-     '[.coupling[]|select(.["crosses-crate"]=="yes")|[.entity,.coupled]|sort]' \
+  is "files of two crates, the root crate's included, cross a boundary" \
-     '[["crates/a/src/lib.rs","crates/b/src/lib.rs"],["crates/a/tests/t.rs","crates/b/src/lib.rs"]]'
+     '[.coupling[]|select(.["crosses-crate"]=="yes")|[.entity,.coupled]|sort]|sort' \
+     '[["crates/a/src/lib.rs","crates/b/src/lib.rs"],["crates/a/src/lib.rs","src/main.rs"],["crates/a/tests/t.rs","crates/b/src/lib.rs"],["crates/a/tests/t.rs","src/main.rs"],["crates/b/src/lib.rs","src/main.rs"]]'
   is "two agent-rule docs are flagged" \
      '[.coupling[]|select(.["agent-rules"]=="yes")|[.entity,.coupled]|sort]' \
      '[[".agents/skills/wave/agent-rules.md","AGENTS.md"]]'
@@ -166,13 +178,32 @@ if run "$work/at-tag" json --ref before-shrink; then
   is "--ref names the ref it read" '.ref' '"before-shrink"'
 fi
 
-# improvise refusing the pipeline is exit 3, whatever the numbers were.
+# A window whose only commits are empty changes no file: exit 0, and no model.
+empty="$work/empty"
+git init -q -b main "$empty"
+repo="$empty"; put README.md 5 old; commit 2026-01-01
+GIT_AUTHOR_DATE=2026-06-02T12:00:00Z GIT_COMMITTER_DATE=2026-06-02T12:00:00Z \
+  g commit -q --allow-empty -m empty
+if run "$work/empty-out" text; then
+  is "an empty commit is counted" '.commits' '1'
+  is "and builds no tables" '.tables' '{}'
+  lines="$(wc -l < "$work/empty-out/churn.csv" | tr -d ' ')"
+  [ "$lines" = 1 ] && ok "churn.csv is written with its header alone" \
+    || bad "churn.csv is written with its header alone" "$lines lines"
+  says "the text report says why there are no tables" "No file changed in the window"
+fi
+repo="$work/repo"
+
+# improvise refusing the pipeline is exit 3, whatever the numbers were. The
+# third stub imports cleanly and refuses only the scripts.
 mkdir -p "$work/bin"
 printf '#!/usr/bin/env bash\necho "Parse error: no" >&2\nexit 1\n' > "$work/bin/refuses"
 printf '#!/usr/bin/env bash\necho "warning: Skipped 3 of 3 records" >&2\nexit 0\n' \
   > "$work/bin/warns"
-chmod +x "$work/bin/refuses" "$work/bin/warns"
+printf '#!/usr/bin/env bash\n[ "$1" = script ] || exit 0\necho "Parse error: no" >&2\nexit 1\n' \
-for stub in refuses warns; do
+  > "$work/bin/refuses-a-script"
+chmod +x "$work/bin/refuses" "$work/bin/warns" "$work/bin/refuses-a-script"
+for stub in refuses warns refuses-a-script; do
   IMPROVISE="$work/bin/$stub" "$STATS" -C "$repo" --since 2026-06-01 --out "$work/$stub" \
     > /dev/null 2>&1
   got=$?