[tyler-dane]

Fixes #

What and why

A debt sweep over the last 7 days of merged changes. Two duplication clusters grew out of recent fixes; both are behavior-preserving to collapse.

refactor(sync): share microsoft iana zone resolution

The Graph zone fallback (IANA passthrough → Windows display-name lookup → UTC on failure) was copied byte-for-byte into microsoft-event.normalizer.ts and microsoft-cancelled-occurrences.ts as the recurrence-zone fixes landed (#4794, #4797, #4805, #4824). It now lives once in microsoft-timezone.ts, so the next zone rule changes in a single place.

Same commit drops the item.type === "exception" branch in mapRecurrence: it was fully subsumed by the seriesMasterId && originalStart branch immediately below it and returned an identical value.

resolveIanaZone in microsoft-recurrence.ts is deliberately left alone. It throws UnsupportedRecurrenceError on an unknown zone rather than falling back to UTC, so folding it in would turn skipped events into imported ones with a guessed UNTIL. That is a product call, not a refactor.

refactor(backend): share the email dispatch send-and-retry tail

#dispatchBookingHostRow and #dispatchWelcomeRow had each grown their own copy of the same tail: a skip closure, the mid-dispatch stop re-check and isQueued claim guard added by #4788, markSent, the email_sent capture, and a catch block that was byte-identical apart from its log prefix. Both now call #skipRow and #deliverRow, passing only what actually differs: the stop re-check, the provider payload, and the welcome path's preview-loop follow-up. 164 lines removed, 146 added, and the duplicated retry/backoff policy has one home.

One intentional log change: the welcome skip log now carries the same reason field the booking skip log already had.

Verify

VERDICT: FAIL
Selected packages: sync, backend
Checks run: test:sync:fast, type-check, lint, knip
Failed: test:backend:fast

test:sync:fast (897 tests), type-check, lint, and knip all pass. test:backend:fast reports 618 pass / 13 fail, and all 13 are environmental, not this diff:

• The failing specs are GET /api/config (3) and SSE Server (10). This diff touches neither; it changes only packages/sync/src/providers/microsoft/* and packages/backend/src/email/email-dispatch.service.ts.
• Stashing the diff and rerunning on the unmodified tree at the same base commit gives the identical result: 618 pass / 13 fail, same 13 spec names.
• Root cause is the sandbox, not config. /api/config returns 500 and the SSE specs time out waiting for userMetadataChanged; mongodb-memory-server in the same sandbox fails with Failed to listen at ::. Adding compass.yaml (cp compass.example.yaml compass.yaml plus bun dev:ports) does not change the count.

CI decides.

---

Generated by Claude Code

[tyler-dane]

Tech-debt sweep: 2026-10-18 → 2026-10-25

Reviewed the 50 non-merge commits merged in the last 7 days. Two duplication clusters were worth a PR; both are in this one, as separate commits.

Addressed here

Debt	Where it came from	Commit
toIanaTimeZone duplicated byte-for-byte across two Microsoft modules	the recurrence-zone fix series (#4794, #4797, #4805, #4824)	ef95167
Dead item.type === "exception" branch in mapRecurrence, subsumed by the branch below it	#4805	ef95167
Booking-host and welcome email dispatch each carrying their own copy of the skip closure, stop re-check, isQueued guard, markSent path and an identical catch	#4780 added the second path, #4788 then grew both in parallel	bc22fd7

Net on the email service: 164 lines removed, 146 added, and the retry/backoff policy now has one home instead of two that have to be kept in step.

Inspected and deliberately left alone

• resolveIanaZone in microsoft-recurrence.ts looks like a third copy of the zone fallback, but it throws UnsupportedRecurrenceError on an unknown zone where the others fall back to UTC. Folding it in would turn skipped events into imported ones with a guessed UNTIL. That is a product call, not a refactor.
• public-booking.service.ts (fix(booking): exhausted failed ops no longer block overlapping bookings #4787, operationIsSpent) and microsoft-recurrence.ts partsToPattern/partsToRange read clean.
• A large share of last week's merges were already debt work (refactor: collapse leftover trial, timezone, and booking helpers #4795, refactor: collapse billing intent gate and microsoft recurrence helpers #4804, simplify: dedupe timed draft overlay checks in GridLayoutSnapshotBuilder #4806, simplify: inline timezone trust checks and dedupe browser zone sync #4809, simplify: drop redundant timed grid draft overlay merge at render #4810, simplify: share truncateSeriesRulesBefore for local recurring splits #4813, simplify: extract EventForm field control ids and focus order util #4815, simplify: extract event mutation optimistic merge helpers #4816, refactor(sync): dedupe live provider smoke setup-and-create block #4817, chore: remove unused TypeScript exports and dead types (knip W4) #4818), so the obvious targets were mostly taken.

Outcome: merged to main as 605c60b at 10:27 UTC via the merge queue. Every check was green on the head commit, unit-leg (sync) and unit-leg (backend) included, which also confirms the 13 backend failures in the PR body's local verdict were sandbox-only.

---

Generated by Claude Code