Fix calendar grid alignment when doesn't start on Monday

[jbouganim]

This issue is live on https://thepocketnyc.com/calendar/grid/

Changes proposed in this Pull Request

• Fix get_start_day() and get_end_day() in class-se-calendar.php so the month grid respects WordPress start_of_week for all values (0–6), not just Monday.
• Replace Monday-only offset math (abs(1 - w) / 7 - w) with ( w - start_of_week + 7 ) % 7 so dates appear under the correct weekday column.
• Normalize grid boundaries to midnight before calculating offsets.

Before: With Week Starts On → Sunday, a month whose 1st falls on Monday (e.g. June 2026) showed the 1st under the Sunday column — headers were correct but dates were shifted.

After: Grid cells align with weekday headers for both Sunday and Monday week starts.

Correct:

Incorrect:

June 9, 26 is a not a Monday.

Testing instructions

1. Add a page with the Simple Events Calendar block.
2. Ensure at least one event exists in the month under test.

Sunday week start (start_of_week = 0)

• Go to Settings → General → Week Starts On → Sunday.
• Open the calendar to June 2026 (1st is a Monday).
• Confirm column headers are Sun–Sat.
• Confirm June 1 appears under Monday, not Sunday.
• Confirm May 31 (Sunday) appears in the leading cell of the first row.
• Confirm events render on the correct calendar dates.

Monday week start (start_of_week = 1)

• Set Week Starts On → Monday.
• Reload June 2026.
• Confirm June 1 appears under Monday (regression check — this case worked before).

Month navigation

• Use prev/next month controls (initial render and AJAX).
• Confirm leading/trailing days from adjacent months still align correctly.
• Confirm events stay on the correct dates after navigation.

Mentions #
@gin0115 @tommusrhodus

Summary by CodeRabbit

• Bug Fixes

  • Fixed calendar grid alignment so dates and events appear under the correct weekday when the week start is set to Sunday or any day other than Monday.

• Chores

  • Version bumped to 2.1.3.

• Documentation

  • Changelog updated to reflect the 2.1.3 fix.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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Reviewing files that changed from the base of the PR and between d28735b and 8f5e632.

📒 Files selected for processing (1)

• src/classes/class-se-calendar.php

🚧 Files skipped from review as they are similar to previous changes (1)

• src/classes/class-se-calendar.php

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Walkthrough

This PR fixes calendar month grid alignment when WordPress "Week Starts On" is configured to a value other than Monday. The get_start_day() and get_end_day() methods in SE_Calendar were rewritten to use modular arithmetic with PHP's weekday format and the WordPress start_of_week option, ensuring grid boundaries align dates and events under the correct weekday columns. Version metadata was bumped to 2.1.3 across package.json, plugin headers, the runtime constant, and the README changelog.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly addresses the primary fix in the changeset: correcting calendar grid alignment when the week doesn't start on Monday by adjusting start_of_week calculations.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
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Inline comments:
In `@src/classes/class-se-calendar.php`:
- Line 448: Update the `@param` docblock for $start_of_week in
class-se-calendar.php: change the type from "int" to "integer" and start the
parameter description with a capital letter or rephrase it (for example:
"WordPress `start_of_week` option: 0 = Sunday through 6 = Saturday.") so the
comment begins with a capitalized word and satisfies PHPCS.
- Line 469: Update the docblock for the parameter $start_of_week in the
SE_Calendar class (where the `@param` currently reads "int $start_of_week
`start_of_week` option: 0 = Sunday through 6 = Saturday.") to use the word
"integer" instead of "int" and start the parameter description with a capital
letter (e.g., "Start_of_week `start_of_week` option: ..." or better "Start of
week `start_of_week` option: ..."), ensuring the `@param` line reads "`@param`
integer $start_of_week Start of week `start_of_week` option: 0 = Sunday through
6 = Saturday." to satisfy PHPCS.

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Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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📥 Commits

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📒 Files selected for processing (4)

• README.md
• package.json
• plugin.php
• src/classes/class-se-calendar.php