Filter H1/H2 from being able to be substituted

[nemvince]

[Dasa122]

@coderabbitai plan

[coderabbitai]

Coding Plan

Summary

• Single backend change in the getSubstitutionCandidates endpoint to filter out H1/H2 lessons
• Leverages the existing in-memory filtering pattern used for weekday matching
• No frontend changes required as the UI already displays whatever lessons the backend returns
• No database or schema changes needed since subject.short is already available in the enriched lesson data

Implementation Steps

Backend Subject Filtering

Add filtering logic to exclude lessons with H1/H2 subject shortcodes from the substitution candidates endpoint. This ensures these special placeholder lessons never appear as options in the substitution dialog.

Filter H1/H2 Lessons from Available Lessons

Modify the getSubstitutionCandidates endpoint to exclude lessons whose subject shortcode is "H1" or "H2" from the availableLessons response.

• Update apps/chronos/src/routes/timetable/lesson.ts in the getSubstitutionCandidates handler
• Extend the existing .filter() chain that builds availableLessons (currently filters by weekday matching around lines 609-618)
• Add an additional predicate that excludes lessons where lesson.subject?.short equals "H1" or "H2"
• Define the excluded shortcodes as a constant array (e.g., ['H1', 'H2']) at the top of the filter logic for clarity and future maintainability
• The filter must occur after enrichLessons() is called since subject data is only available post-enrichment

🤖 Prompt for AI agents

Modify the `getSubstitutionCandidates` endpoint in
`apps/chronos/src/routes/timetable/lesson.ts` to filter out lessons with H1/H2
subject shortcodes from the `availableLessons` response.

- In the `getSubstitutionCandidates` handler, locate the existing `.filter()`
chain that builds `availableLessons` (around lines 609-618), which currently
filters by weekday matching
- Before (or within) that filter chain, define a constant array of excluded
shortcodes (e.g., `['H1', 'H2']`)
- Extend the `.filter()` chain with an additional predicate that excludes
lessons where `lesson.subject?.short` is included in the excluded shortcodes
array
- Ensure this filter is applied after `enrichLessons()` is called, since
`lesson.subject` is only available post-enrichment

Research

This is a school timetable management system with a Hono-based backend (apps/chronos) and React frontend (apps/iris). Substitution functionality allows admins to assign substitute teachers when a teacher is absent. The getSubstitutionCandidates endpoint in apps/chronos/src/routes/timetable/lesson.ts returns available lessons for a given teacher/date combination. Lessons are fetched from the database and enriched with subject data (including subject.short) via an enrichLessons() helper, then filtered in JavaScript by weekday. The subject shortcodes "H1" and "H2" represent special substitution placeholder slots in the imported timetable XML and should be excluded from the substitution workflow.

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🚀 Next Steps

🤖 All AI agent prompts combined

Modify the `getSubstitutionCandidates` endpoint in
`apps/chronos/src/routes/timetable/lesson.ts` to filter out lessons with H1/H2
subject shortcodes from the `availableLessons` response.

- In the `getSubstitutionCandidates` handler, locate the existing `.filter()`
chain that builds `availableLessons` (around lines 609-618), which currently
filters by weekday matching
- Before (or within) that filter chain, define a constant array of excluded
shortcodes (e.g., `['H1', 'H2']`)
- Extend the `.filter()` chain with an additional predicate that excludes
lessons where `lesson.subject?.short` is included in the excluded shortcodes
array
- Ensure this filter is applied after `enrichLessons()` is called, since
`lesson.subject` is only available post-enrichment

💡 Iterate on the plan with: `@coderabbitai` <feedback>

Example Feedback
- `@coderabbitai` You can skip phase 3. Add a simple unit test case for phase 2.
- `@coderabbitai` For design choice 1 go ahead with option 3 and replan.

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