Add timezone support and safe date formatting utilities

[marcelsamyn]

Summary

This PR adds comprehensive timezone support to the database schema and introduces safe date formatting utilities to prevent crashes from invalid date values.

Key Changes

Database Schema Updates

• Timestamp columns: Converted all timestamp columns to timestamp with time zone (timestamptz) across all tables (nodes, edges, embeddings, sources, user_profiles, scratchpads, etc.)
• Migration: Added Drizzle migration 0009_timestamp_to_timestamptz.sql to safely convert existing timestamp columns to timestamptz, treating existing values as UTC

New Safe Date Utilities

• New file: src/lib/safe-date.ts with two exported functions:
  • safeFormatISO(): Safely formats dates as ISO 8601, falling back to current time for invalid dates
  • safeToISOString(): Safely converts dates to ISO strings with the same fallback behavior
  • Internal toValidDate() helper that validates dates and returns current time if invalid

Updated Date Handling

• src/lib/formatting.ts: Replaced direct formatISO() calls with safeFormatISO() for message, node, edge, and connection timestamp formatting
• src/lib/conversation-store.ts: Added inline validation when parsing conversation turn timestamps
• src/lib/extract-graph.ts: Replaced .toISOString() with safeToISOString() for node timestamps
• src/lib/jobs/dream.ts: Replaced .toISOString() with safeToISOString() for node timestamps
• src/lib/jobs/ingest-conversation.ts: Replaced .toISOString() with safeToISOString() for message timestamps

Implementation Details

• The safe date utilities prevent RangeError: Invalid time value crashes that can occur when formatting invalid dates
• All existing timestamp values are preserved during migration by treating them as UTC
• The fallback behavior (using current time for invalid dates) ensures graceful degradation rather than failures

https://claude.ai/code/session_01SDE1HZqgcEgcjWs1UPqAY6

[gemini-code-assist]

Code Review

This pull request migrates database timestamp columns to timestamptz and introduces a new safe-date utility to handle invalid date values gracefully across the application. The review feedback suggests refactoring the internal toValidDate helper into an exported safeToDate function to centralize validation logic and eliminate manual date checks in conversation-store.ts, improving maintainability and consistency.

[gemini-code-assist]

The internal helper function toValidDate is highly reusable. I recommend renaming it to safeToDate to match the naming convention of the other exports in this module and exporting it so it can be used in conversation-store.ts and other parts of the codebase. This avoids duplicating validation logic and the overhead of creating multiple Date objects.

import { formatISO } from "date-fns";

/**
 * Converts a value to a valid Date, returning the current time if invalid.
 */
export function safeToDate(value: Date | string | number): Date {
  const date = value instanceof Date ? value : new Date(value);
  if (isNaN(date.getTime())) {
    return new Date();
  }
  return date;
}

/**
 * Safely formats a date value as ISO 8601.
 * Falls back to the current time if the input is an invalid date,
 * preventing RangeError: Invalid time value crashes.
 */
export function safeFormatISO(value: Date | string | number): string {
  return formatISO(safeToDate(value));
}

/**
 * Safely converts a date value to an ISO string.
 * Falls back to the current time if the input is an invalid date.
 */
export function safeToISOString(value: Date | string | number): string {
  return safeToDate(value).toISOString();
}

[gemini-code-assist]

Instead of duplicating the validation logic and creating multiple Date objects here, use the new safeToDate utility (after exporting it from safe-date.ts). This improves maintainability and ensures consistent fallback behavior across the application. Note: You will need to add the corresponding import for safeToDate.

      timestamp: safeToDate(meta.timestamp),