Nightly PostHog feature flag audit log in Google Sheets

Every night at 11pm in my workspace timezone, run a deterministic audit of every PostHog feature flag change from the previous 24 hours, append the results to a Google Sheet, and ping Slack when a high-blast-radius flag is touched. Build this as a code workflow because every step is a fixed-schema CRUD call with no natural-language synthesis.

Trigger: cron at 23:00 daily.

Step 1. Call PostHog List Feature Flags to enumerate every active flag in the project.

Step 2. For each flag returned, call PostHog Get Feature Flag Activity Log filtered to events with a timestamp in the last 24 hours.

Step 3. For every activity entry, call Google Sheets Append Values on my "Feature Flag Audit" spreadsheet. Write one row per entry with these columns, in order: timestamp, flag key, change type (created, updated, deleted, toggled, archived), rollout percentage before, rollout percentage after, who made the change (name and email when available), and a deep link back to the flag in PostHog.

Step 4. After all rows are appended, scan the new entries for any flag whose rollout percentage moved above 50% in this run, or whose targeting now includes the all-users group. Treat these as high-blast-radius changes.

Step 5. For each high-blast-radius entry, call Slack Send a Message to the #flag-changes channel with the flag key, the user who changed it, the new rollout percentage, and the deep link back to PostHog.

If nothing changed in PostHog in the last 24 hours, the workflow should finish silently. No empty Slack post, no header-only row appended. The Google Sheet is append-only and must never overwrite or delete prior rows.