diff --git a/scripts/README.md b/scripts/README.md
index 7d16e41..24e7950 100644
--- a/scripts/README.md
+++ b/scripts/README.md
@@ -31,7 +31,8 @@ Unavailable properties on `workflowRuns` records, including component AIC values
 omitted rather than serialized as `null`.
 
 Pass `--repo REPO` to collect one non-archived, non-fork repository within `ORG` instead
-of the full visible organization. The resulting snapshot records the repository filter.
+of the full visible organization. The resulting snapshot records the repository filter as
+`repositoryFilter`; like `bot`, it is omitted when the corresponding option is not given.
 
 It requires authenticated `gh` and `unzip`. The snapshot is intentionally written to
 `/tmp` by default, not committed, and reports partial repository/artifact coverage.
diff --git a/scripts/org-history.js b/scripts/org-history.js
index a3d4298..b0bfb13 100644
--- a/scripts/org-history.js
+++ b/scripts/org-history.js
@@ -558,13 +558,17 @@ function selectedRepositories(org, repositoryFilter) {
   return [repository];
 }
 
+function snapshotHeader(org, interval, bot, repositoryFilter) {
+  return sparseProperties({ schemaVersion: SCHEMA_VERSION, org, period: interval.period, bot, repositoryFilter, interval: { start: interval.start, end: interval.end } });
+}
+
 function collect(org, interval, bot, repositoryFilter) {
   // These are global prerequisites: do not turn a missing CLI/authentication
   // problem into misleading per-repository coverage gaps.
   exec('gh', ['auth', 'status']);
   exec('unzip', ['-v']);
   const repositories = selectedRepositories(org, repositoryFilter);
-  const snapshot = { schemaVersion: SCHEMA_VERSION, org, period: interval.period, bot: bot || null, repositoryFilter: repositoryFilter || null, interval: { start: interval.start, end: interval.end }, repositories: [], items: [], workflowRuns: [], commentAic: [], coverage: { repositories: { included: repositories.length, failed: [] }, aic: { relevantRuns: 0, eligibleRuns: 0, runsWithValues: 0, artifactBackedRuns: 0, commentBackedRuns: 0, ineligibleRuns: 0, missingOrExpired: 0, total: null } }, errors: [] };
+  const snapshot = { ...snapshotHeader(org, interval, bot, repositoryFilter), repositories: [], items: [], workflowRuns: [], commentAic: [], coverage: { repositories: { included: repositories.length, failed: [] }, aic: { relevantRuns: 0, eligibleRuns: 0, runsWithValues: 0, artifactBackedRuns: 0, commentBackedRuns: 0, ineligibleRuns: 0, missingOrExpired: 0, total: null } }, errors: [] };
   for (const repo of repositories) {
     let repositoryAic;
     try {
@@ -650,4 +654,4 @@ function main(argv) {
 }
 if (require.main === module) { try { main(process.argv.slice(2)); } catch (error) { console.error(`org-history: ${error.message}`); process.exitCode = 1; } }
 
-module.exports = { aicLinkedItems, applyCommentAicFallback, artifactAicProperties, deduplicateCommentAic, historyFilename, normalizedPullRequests, parseCommentAic, parsePeriod, previousCompleteIsoWeek, summarizeAicCoverage, validateDetailedItems, workflowRunRecord };
+module.exports = { aicLinkedItems, applyCommentAicFallback, artifactAicProperties, deduplicateCommentAic, historyFilename, normalizedPullRequests, parseCommentAic, parsePeriod, previousCompleteIsoWeek, snapshotHeader, summarizeAicCoverage, validateDetailedItems, workflowRunRecord };
diff --git a/tests/org-history.test.js b/tests/org-history.test.js
index c1efded..14a9a24 100644
--- a/tests/org-history.test.js
+++ b/tests/org-history.test.js
@@ -4,7 +4,7 @@ const assert = require('node:assert/strict');
 const childProcess = require('node:child_process');
 const path = require('node:path');
 const test = require('node:test');
-const { aicLinkedItems, applyCommentAicFallback, artifactAicProperties, deduplicateCommentAic, historyFilename, normalizedPullRequests, parseCommentAic, parsePeriod, previousCompleteIsoWeek, summarizeAicCoverage, validateDetailedItems, workflowRunRecord } = require('../scripts/org-history.js');
+const { aicLinkedItems, applyCommentAicFallback, artifactAicProperties, deduplicateCommentAic, historyFilename, normalizedPullRequests, parseCommentAic, parsePeriod, previousCompleteIsoWeek, snapshotHeader, summarizeAicCoverage, validateDetailedItems, workflowRunRecord } = require('../scripts/org-history.js');
 
 const script = path.join(__dirname, '..', 'scripts', 'org-history.js');
 
@@ -94,6 +94,14 @@ test('normalizes only same-repository workflow PR references', () => {
   assert.deepEqual(normalizedPullRequests({ pull_requests: [{ url: 'https://api.github.com/repos/org/repo/pulls/2' }, { url: 'https://api.github.com/repos/org/repo/pulls/1' }, { url: 'https://api.github.com/repos/org/repo/pulls/2' }, { url: 'https://api.github.com/repos/org/other/pulls/3' }] }, 'org', 'repo'), [{ number: 1, url: 'https://github.com/org/repo/pull/1' }, { number: 2, url: 'https://github.com/org/repo/pull/2' }]);
 });
 
+test('omits unset optional snapshot header properties', () => {
+  const interval = parsePeriod('2026-W38');
+  const expected = { schemaVersion: 5, org: 'org', period: '2026-W38', interval: { start: interval.start, end: interval.end } };
+  assert.deepEqual(snapshotHeader('org', interval, undefined, undefined), expected);
+  assert.deepEqual(Object.keys(snapshotHeader('org', interval, 'bot[bot]', 'repo')), ['schemaVersion', 'org', 'period', 'bot', 'repositoryFilter', 'interval']);
+  assert.deepEqual(snapshotHeader('org', interval, 'bot[bot]', 'repo'), { ...expected, bot: 'bot[bot]', repositoryFilter: 'repo' });
+});
+
 test('serializes sparse workflow-run AIC properties without losing zero values', () => {
   const record = workflowRunRecord({
     id: 1, path: 'drafter.lock.yml', aic: 0, aicRecords: 0, aicAgent: 0,