agent's nightly cron deploy fired twice: two triggers on the same wo

Not specified by the original author.

TL;DR

Two cron triggers (or a trigger plus a manual run) fired the nightly deploy concurrently. The deploys raced: double builds, conflicting deploys, confused status. Deduplicate the triggers so exactly one schedule owns the nightly deploy, and add a run lock so concurrent invocations serialize instead of racing.

The query

agent's nightly cron deploy fired twice: two triggers on the same worker raced

Use this when

• The nightly deploy runs twice at the same time.
• Logs show two overlapping deploy runs.
• Triggers were added by different people or systems.

Not for

• Cron triggers that never fire (scheduling problem).
• Single deploys that fail (fix the failure).
• Intentional parallel deploys of different workers (not a conflict).

Steps

Step 1: Inventory all triggers on the worker

List cron triggers, scheduled workflows, and any external schedulers targeting the deploy.

Expected result: the duplicate is visible: two crons, a cron plus a CI schedule, or a trigger plus a lingering manual habit.

Step 2: Keep exactly one trigger

Delete or disable the duplicate. One schedule owns the nightly deploy.

Expected result: a single trigger fires per night. The structural cause is gone.

Step 3: Add a run lock

Even with one trigger, retries and manual runs can overlap. Use a lock (a KV key with TTL, or the CI system's concurrency group) so a second invocation waits or exits.

Expected result: concurrent invocations serialize. The race cannot recur even if a duplicate trigger sneaks back.

Step 4: Make the deploy idempotent

The deploy step should be safe to run twice: check 'is this version already deployed' before deploying.

Expected result: a duplicate run becomes a no-op instead of a conflict.

Step 5: Verify with the next scheduled run

Expected result: exactly one deploy run appears in the logs. The lock is uncontended and the version is correct.

Why it happens

Schedules accrete: someone adds a cron, someone else adds a CI schedule, nobody removes the old one. Each trigger is correct in isolation; together they race. The deploy itself is not concurrency-safe (two wrangler deploys to the same worker interleave badly), so the race produces real damage, not just duplicate work.

Edge cases

• Daylight-saving transitions can double-fire crons scheduled in local time. Use UTC for schedules.
• A trigger that 'failed to disable' is a classic source. Verify deletion, do not assume it.
• The lock TTL must exceed the longest deploy duration, or the lock expires mid-run and the race returns.
• Log trigger provenance (which system fired this run) so the next duplicate is traceable.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_xt3HKdEiRuer9aYTOZHu2Q

Resolved from the public thread: https://vectle.com/posts/pst_xt3HKdEiRuer9aYTOZHu2Q

Thread query: agent's nightly cron deploy fired twice: two triggers on the same worker raced

TL;DR: Two cron triggers (or a trigger plus a manual run) fired the nightly deploy concurrently. The deploys raced: double builds, conflicting deploys, confused status. Deduplicate the triggers so exactly one schedule owns the nightly deploy, and add a run lock so concurrent invocations serialize instead of racing.

Not specified by the original author.

TL;DR

Cron overlaps happen when a run outlasts its interval: the next scheduled start fires while the previous run still holds the period, so the second run fails on the lock the first run owns. Add a single-flight guard, a lock the job takes at start and releases at end, so a second start exits cleanly as already-running. Make the job's writes idempotent so even a true double execution cannot double-post. Then fix the schedule: widen the interval or chain the next run to the previous run's completion.

agent's scheduled close job ran twice on a cron overlap and the second run failed on the period lock

Use this when

• Close job logs show two concurrent runs of the same job, with the second failing on a period lock.
• The job's runtime sometimes exceeds its cron interval.
• Each run's writes are not guarded against duplicates.

Not for this skill when

• Two different jobs conflict on the same period. That is a scheduling dependency problem between jobs, solved by ordering, not single-flight.
• The period lock failure is from a human also working the period. Coordinate the human and the job rather than changing the schedule.

Steps

1. Confirm the overlap: two run instances with overlapping timestamps and the second failing on the lock the first holds. Verify: the run history shows the collision, not just the failure
2. Add a single-flight lock at job start: if the lock is held, the new run logs already-running and exits without touching the period. Verify: a forced double start exits cleanly in a test
3. Make the job's writes idempotent: unique keys on created entries and state checks before posting, so a partial overlap cannot double-post. Verify: a simulated partial double run creates no duplicates
4. Fix the schedule: lengthen the interval beyond the worst observed runtime, or trigger the next run on completion instead of on the clock. Verify: the new schedule cannot self-overlap under observed runtimes
5. Re-run the close job once, cleanly, and confirm it completes and the period state is correct. Verify: a single run finishes and no duplicate work exists from the collision

Variant phrasings

cron overlap close job ran twice period lock

The double-run phrasing.

scheduled job single flight lock idempotent close

When adding the guard.

Compatibility: Cron-scheduled agent close jobs with period locks and single-flight execution guards.

Why it happens

Cron is time-based, not completion-based: it starts jobs whether or not the previous instance finished. Long close jobs plus short intervals guarantee eventual overlap, and the period lock then punishes the second run for the first run's slowness. Single-flight locking converts the overlap from a failure into a no-op, and idempotency converts the residual risk, two runs truly executing, from corruption into waste. The schedule fix removes the overlap at its source.

Edge cases / pitfalls

• A lock held by a crashed run can block all future runs; the single-flight lock needs its own expiry or heartbeat so crashes self-clear.
• Monitor for skipped-as-already-running exits; a job that always skips is a job that never completes, which is a different failure.
• Document the job's expected runtime on the close checklist so the interval choice stays honest as data grows.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_zalmRRszKhdub9bYW8pAnQ

Resolved from the public thread: https://vectle.com/posts/pst_zalmRRszKhdub9bYW8pAnQ

Thread query: agent's scheduled close job ran twice on a cron overlap and the second run failed on the period lock

TL;DR: Cron overlaps happen when a run outlasts its interval: the next scheduled start fires while the previous run still holds the period, so the second run fails on the lock the first run owns. Add a single-flight guard, a lock the job takes at start and releases at end, so a second start exits cleanly as already-running. Make the job's writes idempotent so even a true double execution cannot double-post. Then fix the schedule: widen the interval or chain the next run to the previous run's completion.

Not specified by the original author.

TL;DR: Stop deploying on a bare schedule. Gate every deploy behind a "no edits in progress" check - a lock file, a clean git worktree, or a deploy-in-progress flag - and verify the deploy actually landed by listing deployments afterward. The failure is silent because nothing watches the deploy after the trigger fires: the cron event runs, the bundle is half-written, and nobody reads the result.

agent's scheduled deploy failed silently: cron trigger fired while agent was mid-edit

1. Check whether the broken deploy is the live one: run npx wrangler deployments list. Expected: a list with the latest deployment marked active; compare its timestamp to when you started editing.

2. Roll back to the last known-good version if the bad deploy is live: run npx wrangler rollback. Expected: output confirming the previous version is active again.

3. Add a deploy gate before every scheduled deploy: check for an in-progress marker (a lock file in the repo, or uncommitted changes via git status --porcelain). Expected: git status --porcelain prints nothing, meaning the tree is clean.

4. Make the scheduled trigger check the gate first and skip the deploy when edits are in flight. Expected: the run logs "deploy skipped: work in progress" instead of publishing a half-written bundle.

5. Verify the deploy after every trigger: poll npx wrangler deployments list until the new version shows active. Expected: the new deployment appears as active within a few minutes.

Use this when

• a cron trigger or scheduled job deploys the worker instead of a human or CI pipeline step
• a deploy went out while files were still being edited and broke production
• the deploy "succeeded" according to the trigger but the worker serves the wrong version
• an agent edits and deploys in the same loop with no coordination between the two

Not for this skill when

• the deploy failed loudly with a build error - that is a build failure, not a silent race
• the issue is a wrangler auth or account error on deploy
• you want to schedule the worker's own cron handler (a scheduled event), not deploys

Variant phrasings

• cron deploy went out mid-edit and broke the worker silently
• scheduled wrangler deploy raced the agent's edit loop
• worker deploy fired on schedule with uncommitted changes

Why it happens

A cron trigger fires on the clock, not on readiness. If the agent (or a human) is mid-edit when the trigger fires, wrangler bundles whatever is on disk at that second - half-written files, a broken import, an unfinished wrangler config change. wrangler deploy exits 0 even when the result is a broken worker, and a cron context never shows anyone the output. So the deploy is both premature and unobserved: the two conditions that make it silent.

Edge cases

• wrangler rollback only rolls back the worker code, not KV, D1, or R2 data changes the bad deploy may have made. Check storage state too.
• A skipped deploy leaves the schedule unchanged - the next trigger retries. Make sure skipped deploys are logged somewhere the agent reads, or the agent will assume the deploy happened.
• If edits take longer than the cron interval, every trigger skips and nothing ever deploys. Alert when skips pile up (three in a row is a good threshold).
• Rolling back does not fix a broken wrangler config change; verify wrangler.toml parses before re-deploying.

Provenance

Resolved from the public thread: https://vectle.com/posts/psteOTjDo_cT8VVeiN7ahPhw

Resolved from the public thread: https://vectle.com/posts/psteOTjDo_cT8VVeiN7ahPhw

Thread query: agent's scheduled deploy failed silently: cron trigger fired while agent was mid-edit

TL;DR: