feat: Co-teaching and partial credits (#20)

.gitignore

@@ -30,3 +30,6 @@ coverage/
 # OS
 .DS_Store
 Thumbs.db
+
+# Claude Code local tooling
+.claude/

README.md

@@ -11,7 +11,9 @@ A front-end only web application for scheduling instructor workloads with drag-a
 
 ### Course Management
 Courses should be treated as an instance of a section.
-- Add courses with name, credits, and assigned instructor
+- Add courses with name, credits, and assigned instructor(s)
+- Credits may be fractional (e.g. 2.5)
+- **Co-teaching** — assign multiple instructors to a course and split its credits between them. Each instructor's workload counts only their share, and the split must add up to the course's total credits
 - Edit course details by **double-clicking** on any scheduled course
 - Delete courses (automatically removes from schedule)
 - Drag courses to schedule slots

index.html

@@ -80,7 +80,7 @@ <h2 class="collapsible-header" data-toggle-section="courses">
                             </select>
                             <input type="text" id="courseNumber" placeholder="Course number (e.g. 101)">
                             <input type="text" id="courseName" placeholder="Course name (optional)">
-                            <input type="number" id="courseCredits" placeholder="Credits" min="1" required>
+                            <input type="number" id="courseCredits" placeholder="Credits" min="0.5" step="0.5" required>
                             <input type="text" id="courseQuarterTaken" placeholder="Cohort (e.g. Q1, Q2)">
                             <div class="quarters-offered-dropdown">
                                 <button type="button" class="filter-toggle" data-toggle-quarters="add">Quarters Offered ▼</button>
@@ -169,7 +169,7 @@ <h2>Edit Course</h2>
                 </div>
                 <div class="form-group">
                     <label for="editCourseCredits">Credits</label>
-                    <input type="number" id="editCourseCredits" min="1" required>
+                    <input type="number" id="editCourseCredits" min="0.5" step="0.5" data-action="course-credits-change" required>
                 </div>
                 <div class="form-group">
                     <label for="editCourseQuarterTaken">Cohort</label>
@@ -196,10 +196,11 @@ <h2>Edit Course</h2>
                     </div>
                 </div>
                 <div class="form-group">
-                    <label for="editCourseInstructor">Instructor (this section)</label>
-                    <select id="editCourseInstructor">
-                        <option value="">Select Instructor (Optional)</option>
-                    </select>
+                    <label>Instructors &amp; Credit Split (this section)</label>
+                    <div id="editInstructorRows" class="instructor-rows"></div>
+                    <button type="button" class="btn-secondary add-instructor-row-btn"
+                            data-action="add-instructor-row">+ Add Instructor</button>
+                    <div id="instructorCreditsSummary" class="credits-summary"></div>
                 </div>
                 <div class="form-group">
                     <label for="editCourseSection">Section</label>
@@ -291,7 +292,7 @@ <h2>How to Use</h2>
                 <li><strong>Add Programs</strong> - Create programs (e.g. CPW) to organize courses</li>
                 <li><strong>Add Instructors</strong> - Enter names in the Instructors panel on the left</li>
                 <li><strong>Add Courses</strong> - Add courses to the global catalog with program, number, and credits</li>
-                <li><strong>Assign Instructors</strong> - Double-click a course to assign an instructor for the current schedule</li>
+                <li><strong>Assign Instructors</strong> - Double-click a course to assign one or more instructors for the current schedule, splitting the course's credits between them</li>
                 <li><strong>Add Classrooms</strong> - Create rooms with room numbers</li>
                 <li><strong>Add Time Slots</strong> - Set up shared schedule times for each day (applies to all rooms)</li>
                 <li><strong>Set Quarter</strong> - Choose a quarter (Fall/Winter/Spring/Summer) for each schedule</li>
@@ -306,6 +307,7 @@ <h2>Tips</h2>
             <ul style="line-height: 1.8; margin: 20px 0;">
                 <li>Courses are stored in a <strong>global catalog</strong> shared across all schedules</li>
                 <li><strong>Instructor assignments</strong> are per-schedule and per-section — the same course can have different instructors in different sections and schedules</li>
+                <li><strong>Co-teaching</strong> - Add multiple instructors to a course and split its credits between them; each instructor's workload counts only their share. Credits can be fractional (e.g. 1.5)</li>
                 <li><strong>Instructors</strong> are stored globally and shared across all schedules, so you only need to add them once</li>
                 <li>Set <strong>Quarters Offered</strong> on courses to control which quarters they can be scheduled in</li>
                 <li>Courses with no quarters offered are treated as <strong>"on demand"</strong> and available any quarter</li>

src/app.js

@@ -232,15 +232,14 @@ class App {
             const courseNumber = document.getElementById('editCourseNumber').value.trim() || '';
             const name = document.getElementById('editCourseName').value.trim();
             const credits = document.getElementById('editCourseCredits').value;
-            const instructorId = document.getElementById('editCourseInstructor').value;
             const modality = document.getElementById('editModality').value || 'in-person';
             const quarterTaken = document.getElementById('editCourseQuarterTaken')?.value.trim() || null;
             const quartersOffered = this.#uiState.getQuartersOfferedFromCheckboxes('edit');
             const section = document.getElementById('editCourseSection')?.value.trim() || '';
 
             if (credits) {
                 this.#modals.saveCourseChanges(
-                    courseId, name, credits, instructorId || null,
+                    courseId, name, credits,
                     classroomId, day, timeslot, modality, courseIndex,
                     quarterTaken, programId, courseNumber, quartersOffered, section
                 );
@@ -358,6 +357,12 @@ class App {
                 this.#uiState.updateInstructorFilter(instrId, btn.checked);
                 break;
             }
+            case 'add-instructor-row':
+                this.#modals.addInstructorRow();
+                break;
+            case 'remove-instructor-row':
+                this.#modals.removeInstructorRow(btn.closest('.instructor-row'));
+                break;
         }
     }
 
@@ -434,6 +439,8 @@ class App {
         } else if (action === 'timeslot-edit-end') {
             const { day, ts, start } = el.dataset;
             this.#timeslotManager.edit(day, ts, start, el.value);
+        } else if (action === 'instructor-row-change' || action === 'course-credits-change') {
+            this.#modals.updateCreditsSummary();
         }
     }
 }

src/data/DataStore.js

@@ -248,6 +248,22 @@ export class DataStore {
         if (sd.quarter === undefined) sd.quarter = '';
         delete sd.instructors;
 
+        // Co-teaching migration: a legacy assignment was a bare instructor-id
+        // string. Convert to an array of { instructorId, credits } entries, the
+        // lone instructor taking the course's full credit total.
+        Object.keys(sd.courseInstructors).forEach(key => {
+            const value = sd.courseInstructors[key];
+            if (Array.isArray(value)) return;
+            if (typeof value === 'string' && value) {
+                const courseId = key.includes('::') ? key.split('::')[0] : key;
+                const course = this.#data.courseCatalog.find(c => c.id === courseId);
+                const credits = course ? course.credits : null;
+                sd.courseInstructors[key] = [{ instructorId: value, credits }];
+            } else {
+                delete sd.courseInstructors[key];
+            }
+        });
+
         // Old per-schedule courses array → global catalog
         if (sd.courses) {
             sd.courses.forEach(course => {

src/managers/CourseManager.js

@@ -23,8 +23,8 @@ export class CourseManager {
         const creditsInput = document.getElementById('courseCredits');
         const quarterInput = document.getElementById('courseQuarterTaken');
 
-        const credits = parseInt(creditsInput.value);
-        if (!credits) return;
+        const credits = parseFloat(creditsInput.value);
+        if (!credits || credits <= 0) return;
 
         const quartersOffered = this.#uiState.getQuartersOfferedFromCheckboxes('add');
 

src/managers/InstructorManager.js

@@ -34,7 +34,9 @@ export class InstructorManager {
         // Check ALL schedules for assignments (instructors are global)
         for (const [scheduleName, sd] of Object.entries(d.schedules)) {
             if (sd.courseInstructors) {
-                const hasAssignments = Object.values(sd.courseInstructors).some(iId => iId === id);
+                const hasAssignments = Object.values(sd.courseInstructors).some(value =>
+                    Helpers.normalizeInstructorAssignments(value).some(a => a.instructorId === id)
+                );
                 if (hasAssignments) {
                     alert(`Cannot delete instructor with assigned courses in schedule "${scheduleName}". Unassign them first.`);
                     return;
@@ -51,27 +53,31 @@ export class InstructorManager {
         const d = this.#dataStore.data;
         const sd = this.#dataStore.getCurrentSchedule();
 
-        // Collect all unique (courseId, section) keys that are in the grid
-        const scheduledPairs = new Set();
+        // Collect all unique (courseId, section) pairs that are in the grid.
+        const scheduledPairs = new Map(); // key -> { courseId, section }
         for (const classroomId in d.schedule) {
             for (const day in d.schedule[classroomId]) {
                 for (const time in d.schedule[classroomId][day]) {
                     const slotData = d.schedule[classroomId][day][time];
                     const items = Array.isArray(slotData) ? slotData : (slotData ? [slotData] : []);
                     items.forEach(item => {
-                        scheduledPairs.add(Helpers.getCourseInstructorKey(item.courseId, item.section));
+                        const section = item.section || '';
+                        const key = Helpers.getCourseInstructorKey(item.courseId, section);
+                        scheduledPairs.set(key, { courseId: item.courseId, section });
                     });
                 }
             }
         }
 
-        // Sum credits for unique pairs assigned to this instructor
+        // Sum this instructor's credit share across each unique scheduled pair.
         let total = 0;
-        scheduledPairs.forEach(key => {
-            if (sd.courseInstructors[key] === instructorId) {
-                const courseId = key.includes('::') ? key.split('::')[0] : key;
-                const course = d.courseCatalog.find(c => c.id === courseId);
-                if (course) total += course.credits;
+        scheduledPairs.forEach(({ courseId, section }) => {
+            const course = d.courseCatalog.find(c => c.id === courseId);
+            if (!course) return;
+            const assignment = Helpers.getInstructorAssignments(sd, courseId, section)
+                .find(a => a.instructorId === instructorId);
+            if (assignment) {
+                total += assignment.credits == null ? course.credits : assignment.credits;
             }
         });
         return total;

src/ui/CohortSummaryView.js

@@ -127,7 +127,7 @@ export class CohortSummaryView {
                 return `
                     <div class="cohort-class">
                         <div class="cohort-class-name">${cls.name}</div>
-                        <div class="cohort-class-info">${cls.credits} credits</div>
+                        <div class="cohort-class-info">${Helpers.formatCredits(cls.credits)} credits</div>
                         <div class="cohort-schedule-list">${scheduleHTML}</div>
                     </div>
                 `;
@@ -138,7 +138,7 @@ export class CohortSummaryView {
                     <h3 class="cohort-name">Cohort: ${cohort.name}</h3>
                     <div class="cohort-stats">
                         <span class="cohort-stat"><strong>Days per week:</strong> ${daysPerWeek > 0 ? daysPerWeek : 'N/A'}</span>
-                        <span class="cohort-stat"><strong>Total credits:</strong> ${totalCredits}</span>
+                        <span class="cohort-stat"><strong>Total credits:</strong> ${Helpers.formatCredits(totalCredits)}</span>
                     </div>
                     <div class="cohort-classes-list">${classesHTML}</div>
                 </div>