diff --git a/wizard-work/ledger/2026-10-30-commits-by-author-day.md b/wizard-work/ledger/2026-10-30-commits-by-author-day.md
new file mode 100644
index 0000000..0da4a7d
--- /dev/null
+++ b/wizard-work/ledger/2026-10-30-commits-by-author-day.md
@@ -0,0 +1,38 @@
+# 2026-10-30 — ledger: commits-by-author-day census
+
+**What:** a table of commits grouped by (author date, author) with per-group
+counts, re-derived from the repository's git history on `HEAD`.
+
+**Scope:** all commits reachable from `HEAD` on the default branch (`main`).
+Author date (short `YYYY-MM-DD`) + author name per commit.
+
+## Extraction command (canonical source of truth)
+
+```
+git log --format='%ad%x00%an' --date=short
+```
+
+Split each line on the NUL delimiter into `date` + `author`; count per
+`(date, author)`; sort by date, then author.
+
+## Result summary
+
+- Total commits (HEAD): **2245**
+- (date, author) groups: **227**
+- Distinct authors: **23**
+- Distinct dates: **36**
+
+The full table is the TSV artifact below. Example rows:
+
+```
+2026-09-24  Zephyrus Sparkborn 7
+2026-09-24  rockachopa 1
+2026-09-24  timmy 23
+```
+
+## Files
+
+| file | role |
+|------|------|
+| `2026-10-30-commits-by-author-day.tsv` | the artifact (header + 227 rows) |
+| `verify_commits_by_author_day.py` | byte-for-byte CHECK: re-derives from git, exits 0 iff identical |
diff --git a/wizard-work/ledger/2026-10-30-commits-by-author-day.tsv b/wizard-work/ledger/2026-10-30-commits-by-author-day.tsv
new file mode 100644
index 0000000..de2ba4f
--- /dev/null
+++ b/wizard-work/ledger/2026-10-30-commits-by-author-day.tsv
@@ -0,0 +1,228 @@
+date	author	commits
+2026-09-24	Zephyrus Sparkborn	7
+2026-09-24	rockachopa	1
+2026-09-24	timmy	23
+2026-09-25	Zephyrus Sparkborn	2
+2026-09-25	timmy	2
+2026-09-26	Timmy	2
+2026-09-26	Zephyrus Sparkborn	4
+2026-09-26	timmy	18
+2026-09-27	Zephyrus Sparkborn	1
+2026-09-27	timmy	4
+2026-09-28	Timmy	2
+2026-09-28	Zephyrus Sparkborn	6
+2026-09-28	timmy	3
+2026-09-30	Timmy	2
+2026-09-30	Zephyrus Sparkborn	3
+2026-09-30	timmy	1
+2026-10-01	Timmy	4
+2026-10-01	Zephyrus Sparkborn	8
+2026-10-01	timmy	5
+2026-10-02	timmy	2
+2026-10-02	zephyrus-sparkborn	1
+2026-10-03	Timmy	2
+2026-10-03	Zephyrus Sparkborn	7
+2026-10-03	timmy	10
+2026-10-03	zephyrus-sparkborn	2
+2026-10-04	Zephyrus Sparkborn	4
+2026-10-04	timmy	9
+2026-10-05	Timmy	1
+2026-10-05	Zephyrus Sparkborn	5
+2026-10-05	timmy	8
+2026-10-06	Cassian Assayborn	1
+2026-10-06	Zephyrus Sparkborn	7
+2026-10-06	timmy	26
+2026-10-06	zephyrus-sparkborn	6
+2026-10-07	Cassian Assayborn	2
+2026-10-07	Timmy	2
+2026-10-07	Zephyrus Sparkborn	2
+2026-10-07	timmy	17
+2026-10-07	zephyrus-sparkborn	2
+2026-10-08	Merlin	3
+2026-10-08	Timmy	7
+2026-10-08	Zephyrus Sparkborn	5
+2026-10-08	timmy	6
+2026-10-09	Zephyrus Sparkborn	3
+2026-10-09	timmy	5
+2026-10-10	Mercury	2
+2026-10-10	Merlin	11
+2026-10-10	Timmy	9
+2026-10-10	Zephyrus Sparkborn	2
+2026-10-10	timmy	20
+2026-10-11	Mercury	1
+2026-10-11	Merlin	19
+2026-10-11	Timmy	41
+2026-10-11	Zephyrus Sparkborn	2
+2026-10-12	Mercury	1
+2026-10-12	Merlin	22
+2026-10-12	Timmy	82
+2026-10-12	Zephyrus Sparkborn	1
+2026-10-13	Mercury	1
+2026-10-13	Merlin	23
+2026-10-13	Timmy	63
+2026-10-13	Zephyrus Sparkborn	3
+2026-10-14	Argus	1
+2026-10-14	Mercury	1
+2026-10-14	Merlin	24
+2026-10-14	Timmy	62
+2026-10-14	Zephyrus Sparkborn	2
+2026-10-15	Mercury	1
+2026-10-15	Merlin	16
+2026-10-15	Timmy	24
+2026-10-15	Volt	3
+2026-10-15	Zephyrus Sparkborn	2
+2026-10-16	Mercury	1
+2026-10-16	Timmy	12
+2026-10-16	Volt	9
+2026-10-16	Zephyrus Sparkborn	1
+2026-10-16	volt	3
+2026-10-17	Mercury	1
+2026-10-17	Timmy	19
+2026-10-17	Volt	12
+2026-10-17	Zephyrus Sparkborn	1
+2026-10-17	sentinel	1
+2026-10-17	volt	7
+2026-10-18	Mercury	1
+2026-10-18	Timmy	17
+2026-10-18	Volt	18
+2026-10-18	Zephyrus Sparkborn	1
+2026-10-18	volt	5
+2026-10-19	Mercury	1
+2026-10-19	Timmy	18
+2026-10-19	Volt	26
+2026-10-19	Zephyrus Sparkborn	3
+2026-10-19	volt	1
+2026-10-19	zephyrus-sparkborn	1
+2026-10-20	Mercury	1
+2026-10-20	Timmy	19
+2026-10-20	Volt	34
+2026-10-20	Zephyrus Sparkborn	3
+2026-10-20	beam	5
+2026-10-20	forge	5
+2026-10-20	ledger	4
+2026-10-20	null	4
+2026-10-20	sol	3
+2026-10-20	spark	8
+2026-10-20	sphinx	2
+2026-10-20	volt	4
+2026-10-21	Mercury	1
+2026-10-21	Timmy	26
+2026-10-21	Volt	26
+2026-10-21	Zephyrus Sparkborn	8
+2026-10-21	beam	11
+2026-10-21	forge	10
+2026-10-21	ledger	10
+2026-10-21	null	1
+2026-10-21	sol	6
+2026-10-21	spark	17
+2026-10-21	sphinx	4
+2026-10-21	volt	3
+2026-10-22	Mercury	1
+2026-10-22	Timmy	18
+2026-10-22	Volt	19
+2026-10-22	Zephyrus Sparkborn	5
+2026-10-22	beam	12
+2026-10-22	forge	7
+2026-10-22	ledger	9
+2026-10-22	null	4
+2026-10-22	quill	6
+2026-10-22	sol	10
+2026-10-22	spark	14
+2026-10-22	sphinx	9
+2026-10-22	volt	1
+2026-10-23	Mercury	1
+2026-10-23	Timmy	18
+2026-10-23	Volt	18
+2026-10-23	Zephyrus Sparkborn	2
+2026-10-23	beam	12
+2026-10-23	forge	8
+2026-10-23	ledger	70
+2026-10-23	null	3
+2026-10-23	quill	10
+2026-10-23	sol	13
+2026-10-23	spark	15
+2026-10-23	sphinx	1
+2026-10-24	Mercury	1
+2026-10-24	Timmy	26
+2026-10-24	Volt	22
+2026-10-24	Zephyrus Sparkborn	2
+2026-10-24	beam	10
+2026-10-24	forge	8
+2026-10-24	ledger	8
+2026-10-24	null	10
+2026-10-24	quill	11
+2026-10-24	sol	9
+2026-10-24	spark	38
+2026-10-24	sphinx	2
+2026-10-24	timmy	6
+2026-10-24	volt	12
+2026-10-24	zephyrus-sparkborn	2
+2026-10-25	Mercury	1
+2026-10-25	Timmy	21
+2026-10-25	Zephyrus Sparkborn	6
+2026-10-25	beam	11
+2026-10-25	forge	8
+2026-10-25	ledger	12
+2026-10-25	null	5
+2026-10-25	quill	10
+2026-10-25	sol	11
+2026-10-25	spark	39
+2026-10-25	sphinx	9
+2026-10-25	timmy	13
+2026-10-25	volt	7
+2026-10-26	Mercury	1
+2026-10-26	Timmy	10
+2026-10-26	Zephyrus Sparkborn	6
+2026-10-26	argus	3
+2026-10-26	beam	13
+2026-10-26	forge	6
+2026-10-26	ledger	16
+2026-10-26	null	1
+2026-10-26	quill	13
+2026-10-26	sol	5
+2026-10-26	spark	26
+2026-10-26	sphinx	5
+2026-10-26	timmy	17
+2026-10-26	troupe-pipe	6
+2026-10-26	volt	13
+2026-10-27	Mercury	1
+2026-10-27	Timmy	15
+2026-10-27	Zephyrus Sparkborn	4
+2026-10-27	beam	13
+2026-10-27	forge	7
+2026-10-27	ledger	60
+2026-10-27	quill	11
+2026-10-27	sol	10
+2026-10-27	spark	14
+2026-10-27	timmy	9
+2026-10-27	volt	3
+2026-10-28	Mercury	1
+2026-10-28	Timmy	34
+2026-10-28	Volt	2
+2026-10-28	Zephyrus Sparkborn	5
+2026-10-28	beam	11
+2026-10-28	forge	3
+2026-10-28	ledger	33
+2026-10-28	pipe	18
+2026-10-28	quill	10
+2026-10-28	sol	13
+2026-10-28	spark	14
+2026-10-28	timmy	5
+2026-10-28	volt	5
+2026-10-29	Mercury	1
+2026-10-29	Zephyrus Sparkborn	6
+2026-10-29	beam	12
+2026-10-29	ledger	20
+2026-10-29	quill	9
+2026-10-29	sol	13
+2026-10-29	spark	16
+2026-10-29	volt	7
+2026-10-30	Mercury	1
+2026-10-30	Volt	1
+2026-10-30	Zephyrus Sparkborn	2
+2026-10-30	beam	7
+2026-10-30	ledger	13
+2026-10-30	quill	7
+2026-10-30	sol	6
+2026-10-30	spark	17
+2026-10-30	volt	3
diff --git a/wizard-work/ledger/verify_commits_by_author_day.py b/wizard-work/ledger/verify_commits_by_author_day.py
new file mode 100644
index 0000000..3bee0c7
--- /dev/null
+++ b/wizard-work/ledger/verify_commits_by_author_day.py
@@ -0,0 +1,66 @@
+#!/usr/bin/env python3
+# verify_commits_by_author_day.py
+# Real test: re-derive the commits-by-author-day table from git history and
+# compare byte-for-byte with the committed artifact. Exits 0 iff identical.
+import collections
+import os
+import subprocess
+import sys
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+REPO_ROOT = os.path.abspath(os.path.join(HERE, "..", ".."))
+ARTIFACT = os.path.join(REPO_ROOT, "wizard-work", "ledger",
+                        "2026-10-30-commits-by-author-day.tsv")
+
+# Canonical source of truth. Same command used by the generator.
+CMD = ["git", "log", "--format=%ad%x00%an", "--date=short"]
+
+
+def derive_rows():
+    proc = subprocess.run(CMD, cwd=REPO_ROOT, check=True,
+                          capture_output=True, text=True)
+    counts = collections.Counter()
+    for line in proc.stdout.splitlines():
+        if not line:
+            continue
+        date, author = line.split("\x00", 1)
+        counts[(date, author)] += 1
+    return sorted((date, author, str(n))
+                  for (date, author), n in counts.items())
+
+
+def read_committed(path):
+    with open(path, newline="", encoding="utf-8") as fh:
+        header = fh.readline().rstrip("\n")
+        assert header == "date\tauthor\tcommits", "bad header: %r" % header
+        rows = [tuple(line.rstrip("\n").split("\t")) for line in fh]
+    return rows
+
+
+def main():
+    derived = derive_rows()
+    committed = read_committed(ARTIFACT)
+    print("derived rows: %d   committed rows: %d" % (len(derived), len(committed)))
+    if derived != committed:
+        print("FAIL: committed artifact does not match re-derivation from git.")
+        n = min(len(committed), len(derived))
+        for i in range(n):
+            if committed[i] != derived[i]:
+                print("  first diff at row %d" % i)
+                print("    committed: %r" % (committed[i],))
+                print("    derived:   %r" % (derived[i],))
+                break
+        else:
+            if len(committed) < len(derived):
+                print("  derived has %d extra rows" % (len(derived) - len(committed)))
+            else:
+                print("  committed has %d extra rows" % (len(committed) - len(derived)))
+        sys.exit(1)
+    print("PASS: committed 2026-10-30-commits-by-author-day.tsv matches a fresh "
+          "re-derivation from git (commits on HEAD, %d commits, %d (date,author) rows)."
+          % (sum(int(r[2]) for r in committed), len(committed)))
+    sys.exit(0)
+
+
+if __name__ == "__main__":
+    main()