fix(server): resolve comparison periods in timezone

[jack-arturo]

Summary

• resolve named comparison periods in the request or configured timezone
• reject reversed same-day clocks after named-period expansion
• add deterministic MCP contract coverage

Breaking changes

None.

Related to #39.

[chatgpt-codex-connector]

💡 Codex Review

mcp-pirsch/src/utils.ts

Line 30 in 6dca05e

const day = now.getUTCDay();

Use the timezone-local weekday for weekly periods

When the requested timezone's calendar date differs from UTC, start represents the local date but now.getUTCDay() represents the UTC date, shifting both week and lastWeek by one day. For example, at 2026-08-03T00:30Z in America/Los_Angeles, the local date is Sunday August 2 but this computes the week start as Sunday August 2 rather than Monday July 27. Derive the weekday from the timezone-normalized start instead.

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[jack-arturo]

Fixed in 8a24e45: week and lastWeek now derive the weekday from the timezone-normalized calendar date. Added a Los Angeles midnight-boundary regression test.