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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview, Comment	Jul 7, 2026 7:27pm

PR Summary

Medium Risk
Changes how date values are stored, validated, and coerced across imports and inline edits—incorrect timezone stamping could shift instants for existing workflows, though behavior is heavily unit-tested.

Overview
Table date cells now normalize on write to either a calendar YYYY-MM-DD or an RFC 3339 instant with a preserved offset, instead of ad-hoc ISO conversion. Shared logic in lib/table/dates drives server validation, CSV coercion, and client parse/display so everyone sees the literal wall time that was stored (optional seconds in editors), with naive datetimes stamped once using the writer’s effective IANA zone.

CSV import (sync, async, and background jobs) accepts an optional timezone, validates it, defaults from user settings → UTC, and threads it through coerceRowsForTable so Excel/Sheets-style naive datetimes import consistently. Client upload hooks send the user’s timezone.

The grid and row modal gain date + time editing (Calendar showTime, ChipTimePicker, improved blur/focus and “unchanged draft” saves so offsets aren’t re-stamped). Display/paste/expanded editor paths use the new helpers; invalid calendar days (e.g. 02/30) are rejected.

^{Reviewed by Cursor Bugbot for commit 11a9151. Bugbot is set up for automated code reviews on this repo. Configure here.}

Greptile Summary

This PR replaces the previous "store-as-ISO, display in viewer's timezone" model for table date cells with a wall-clock-faithful canonical form: calendar dates stay as YYYY-MM-DD (timezone-free) and datetimes are stored as RFC 3339 with the writer's preserved offset (2026-07-06T16:04:55-07:00). Display is deterministic — every viewer sees exactly the literal wall time that was written.

• Adds lib/table/dates.ts (pure, shared between server coercion and client rendering) with normalizeDateCellValue, formatDateCellDisplay, and related utilities; the Calendar single mode gains showTime and an optional today prop for effective-timezone anchoring.
• Threads the user's effective timezone through all CSV import paths (sync, async, drag-drop) and through the inline editor, expanded-cell editor, and row modal so naive datetimes are stamped once at write time with the correct offset.
• Fixes Calendar UTC-day highlighting for offset instants, displayToStorage accepting rolled-over dates like 02/30, and the midnight guard that silently dropped time for zone-local midnight instants.

Confidence Score: 5/5

The change is safe to merge. The core date canonicalization logic is well-tested and correct; all three previously identified bugs (midnight guard, rolled-over calendar days, UTC-day highlighting) are fixed.

The new dates.ts module is pure and thoroughly unit-tested across DST months, idempotency, legacy UTC-midnight detection, and wall-clock display invariants. The write path (inline editor, expanded editor, row modal, paste, CSV import) consistently stamps naive datetimes with the writer's effective timezone and preserves explicit offsets byte-identical. The untouched-draft fast-path in the inline editor prevents re-stamping stored offsets with a different viewer's zone. No data-loss or incorrect-offset path was found.

No files require special attention. The only minor items are doc-comment consistency in dates.ts (the barrel now re-exports it, making the old "never use the barrel" warning slightly misleading) and the documented DST fall-back ambiguity in wallTimeInZoneToUtc.

Important Files Changed

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant UI as UI (browser)
    participant Utils as utils.ts
    participant Dates as dates.ts
    participant Server as API route
    participant DB as Database

    Note over UI,DB: Write path (inline editor / row modal / paste)
    UI->>Utils: displayToStorage(draft, timeZone)
    Utils->>Dates: "normalizeDateCellValue(raw, {timezone})"
    Note right of Dates: explicit offset → preserve as-is<br/>naive datetime → stamp with zone offset<br/>date-only → YYYY-MM-DD
    Dates-->>Utils: canonical (2026-07-06T16:04:55-07:00)
    Utils-->>UI: canonical value
    UI->>Server: "PATCH /table/{id}/row"
    Server->>Dates: normalizeDateCellValue(value)
    Dates-->>Server: normalized
    Server->>DB: INSERT canonical value

    Note over UI,DB: Read / display path
    DB-->>UI: stored value
    UI->>Dates: "formatDateCellDisplay(stored, {seconds})"
    Note right of Dates: YYYY-MM-DD → MM/DD/YYYY<br/>T00:00:00Z → UTC day (legacy)<br/>offset instant → literal wall time
    Dates-->>UI: 07/06/2026 4:04 PM

    Note over UI,DB: CSV import path
    UI->>Server: "POST /import {file, timezone}"
    Server->>Dates: "normalizeDateCellValue(cellValue, {timezone})"
    Note right of Dates: naive Excel/Sheets value stamped with user zone
    Dates-->>Server: canonical
    Server->>DB: INSERT canonical value

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
    participant UI as UI (browser)
    participant Utils as utils.ts
    participant Dates as dates.ts
    participant Server as API route
    participant DB as Database

    Note over UI,DB: Write path (inline editor / row modal / paste)
    UI->>Utils: displayToStorage(draft, timeZone)
    Utils->>Dates: "normalizeDateCellValue(raw, {timezone})"
    Note right of Dates: explicit offset → preserve as-is<br/>naive datetime → stamp with zone offset<br/>date-only → YYYY-MM-DD
    Dates-->>Utils: canonical (2026-07-06T16:04:55-07:00)
    Utils-->>UI: canonical value
    UI->>Server: "PATCH /table/{id}/row"
    Server->>Dates: normalizeDateCellValue(value)
    Dates-->>Server: normalized
    Server->>DB: INSERT canonical value

    Note over UI,DB: Read / display path
    DB-->>UI: stored value
    UI->>Dates: "formatDateCellDisplay(stored, {seconds})"
    Note right of Dates: YYYY-MM-DD → MM/DD/YYYY<br/>T00:00:00Z → UTC day (legacy)<br/>offset instant → literal wall time
    Dates-->>UI: 07/06/2026 4:04 PM

    Note over UI,DB: CSV import path
    UI->>Server: "POST /import {file, timezone}"
    Server->>Dates: "normalizeDateCellValue(cellValue, {timezone})"
    Note right of Dates: naive Excel/Sheets value stamped with user zone
    Dates-->>Server: canonical
    Server->>DB: INSERT canonical value

_{Reviews (2): Last reviewed commit: "fix(tables): address review — preserve m..." | Re-trigger Greptile}

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