fix(agents): execute same-cycle due schedules in deterministic order

[Glavin001]

Summary

The alarm() due-schedule scan had no ORDER BY:

SELECT * FROM cf_agents_schedules WHERE time <= ${now}

When multiple schedule rows are due in the same alarm cycle (common after a DO restart, a delayed alarm, or accumulated overdue rows), their relative execution order was an accident of the storage engine's scan order. Any interaction between same-cycle schedules — e.g. an app-level watchdog schedule racing the SDK's _chatRecoveryContinue continuation — was racy and unreproducible: whichever row happened to scan first changed the outcome.

This orders the scan deterministically:

SELECT * FROM cf_agents_schedules WHERE time <= ${now}
ORDER BY time ASC, id ASC

so earlier-due schedules always dispatch first and same-time ties break stably by id. The fiber-recovery scan over cf_agents_runs (_runFiberRecoveryPass) is aligned the same way (ORDER BY created_at ASC, id ASC) so recovery of orphaned runs is also processed oldest-first and reproducibly.

Kept deliberately minimal (two ORDER BY clauses) so it rebases cleanly onto the AgentScheduler extraction in cloudflare#1897.

Regression test

schedule.test.ts › "same-cycle deterministic ordering": a TestScheduleAgent helper inserts already-due rows in an order that contradicts (time, id) order, drives alarm() once in-instance, and asserts the callbacks executed in (time, id) order. Both cases fail without the ORDER BY (dispatch follows insertion/scan order) and pass with it.

Includes a patch changeset for agents.

Link to Devin session: https://app.devin.ai/sessions/1745b6a41ce947c69f12ffcd9c1dd9d9
Requested by: @Glavin001

---

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment, CI, and merge conflict monitoring

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 1 additional finding.

[devin-ai-integration]

Tested end-to-end via the workers-pool test suite (@cloudflare/vitest-pool-workers).

Results

• ✅ Both new "same-cycle deterministic ordering" tests pass on this branch
• ✅ Full schedule.test.ts suite: 54/54 passed, run 3× with no flakes
• ✅ Failing-first verified: with src/index.ts reverted to main (no ORDER BY time ASC, id ASC), both new tests fail deterministically (3 retries each), then pass again after restoring the fix

Failing-first evidence (fix reverted to main)

 × should execute schedules due at the same time in id order (retry x3)
   → expected [ 'c-third', 'b-second', 'a-first' ] to deeply equal [ 'a-first', 'b-second', 'c-third' ]
 × should execute schedules due in the same cycle in time order (retry x3)
   → expected [ 'a-due-later', 'b-due-earlier' ] to deeply equal [ 'b-due-earlier', 'a-due-later' ]
 Tests  2 failed | 52 skipped (54)

Passing run on this branch

 ✓ schedule.test.ts > same-cycle deterministic ordering > should execute schedules due at the same time in id order
 ✓ schedule.test.ts > same-cycle deterministic ordering > should execute schedules due in the same cycle in time order
 Test Files  1 passed (1)
 Tests  54 passed (54)

Note: the fiber-recovery scan ordering (ORDER BY created_at ASC, id ASC on cf_agents_runs) has no dedicated failing-first regression test; it's covered only by the suite passing overall.

Tested by Devin