Phase 6: participation grading, gradebook passback, opt-out integrity

Ports the timing-neutral foregone-participation grading scheme from
participation_grades.R: answer quality (per-course level points) minus
a deduction for participation foregone through unavailability,
estimated by Monte Carlo simulation of the actual weighted draw and
averaged over when absences fall, plus a small form-filing incentive
for drawn-while-absent-without-opt-out days. Reason-blind and
luck-protected; zero-answer students floor to 0. Parameters
(allowance in SD units, passing line, form penalty, simulation
size/seed) are course settings. Verified against the R engine's
rendered 2026q2 reports via the new import-legacy command: quality and
availability match exactly, finals within Monte Carlo noise; dropped
students import as inactive enrollments and are excluded identically.

Grades are computed on demand into stored GradeRun snapshots and
reviewed on a grades page with CSV export and per-student reports
(also served to students via a publish toggle). Display scales map
points to UW 4.0, a threshold table (one-click import of the Canvas
course grading scheme), or raw points. Gradebook passback via AGS
sits behind a settings toggle with a review-then-push flow.

Opt-out withdrawals are now soft-deletes with a withdrawn_at audit
trail, and close when class begins (class days gained optional start
times), so availability records cannot be rewritten after the fact.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_grades_ui.py

@@ -0,0 +1,123 @@
+import datetime
+import re
+
+import pytest
+
+from conftest import outcome_actions
+
+TODAY = datetime.date.today().isoformat()
+
+
+@pytest.fixture
+def instructor(dev_client):
+    dev_client.post("/dev/launch/dev-instructor")
+    # Speed: shrink the simulation for tests.
+    dev_client.post(
+        "/instructor/settings",
+        data={"selection_mode": "weighted", "weight_factor": "2",
+              "show_assessments": "on", "n_sims": "200", "sim_seed": "1"},
+    )
+    return dev_client
+
+
+def record_calls(client, n=6):
+    for _ in range(n):
+        client.post("/instructor/live/next", data={"date": TODAY})
+        page = client.get(f"/instructor/live?date={TODAY}").get_data(as_text=True)
+        call_id = re.search(r"/instructor/call/(\d+)/outcome", page).group(1)
+        client.post(
+            f"/instructor/call/{call_id}/outcome",
+            data={"action": outcome_actions(page)["GOOD"]},
+        )
+
+
+def test_grades_page_before_compute(instructor):
+    page = instructor.get("/instructor/grades/").get_data(as_text=True)
+    assert "No grades computed yet" in page
+
+
+def test_compute_and_view_grades(instructor):
+    record_calls(instructor)
+    resp = instructor.post(
+        "/instructor/grades/compute", follow_redirects=True
+    )
+    page = resp.get_data(as_text=True)
+    assert "SD of full-attendance counts" in page
+    assert "4.00" in page          # someone answered GOOD -> full marks
+    assert "never answered" in page  # not everyone got called
+
+    resp = instructor.get("/instructor/grades/export.csv")
+    assert resp.mimetype == "text/csv"
+    assert "final_points" in resp.get_data(as_text=True)
+
+
+def test_student_report_and_publishing(instructor):
+    record_calls(instructor)
+    instructor.post("/instructor/grades/compute")
+    page = instructor.get("/instructor/grades/").get_data(as_text=True)
+    student_id = re.search(r"/instructor/grades/student/(\d+)", page).group(1)
+    report = instructor.get(
+        f"/instructor/grades/student/{student_id}"
+    ).get_data(as_text=True)
+    assert "How your grade was computed" in report
+
+    # Unpublished: students see no report link and get 404.
+    instructor.post("/dev/launch/dev-student-1")
+    assert "participation grade report" not in instructor.get("/me").get_data(as_text=True)
+    assert instructor.get("/me/report").status_code == 404
+
+    # Publish, and the student can read their own report.
+    instructor.post("/dev/launch/dev-instructor")
+    instructor.post(
+        "/instructor/settings",
+        data={"selection_mode": "weighted", "weight_factor": "2",
+              "publish_grade_reports": "on"},
+    )
+    instructor.post("/dev/launch/dev-student-1")
+    page = instructor.get("/me").get_data(as_text=True)
+    assert "participation grade report" in page
+    report = instructor.get("/me/report").get_data(as_text=True)
+    assert "How your grade was computed" in report
+    assert "Ada Lovelace" in report
+
+
+def test_push_flow_dev_mode(instructor):
+    record_calls(instructor)
+    instructor.post("/instructor/grades/compute")
+
+    # Push pages don't exist until AGS is enabled.
+    assert instructor.get("/instructor/grades/push").status_code == 404
+
+    instructor.post(
+        "/instructor/settings",
+        data={"selection_mode": "weighted", "weight_factor": "2",
+              "ags_enabled": "on"},
+    )
+    page = instructor.get("/instructor/grades/push").get_data(as_text=True)
+    assert "Review before pushing" in page
+    assert "Push 8 grades to Canvas" in page
+
+    resp = instructor.post("/instructor/grades/push")
+    page = resp.get_data(as_text=True)
+    assert "simulated (dev mode)" in page
+    assert "8 of\n  8 pushed successfully" in page or "8 of" in page
+
+
+def test_grades_require_instructor(dev_client):
+    dev_client.post("/dev/launch/dev-instructor")
+    dev_client.post("/dev/launch/dev-student-1")
+    assert dev_client.get("/instructor/grades/").status_code == 403
+
+
+def test_scale_settings_and_canvas_import(instructor):
+    # Threshold rows via the settings form.
+    instructor.post(
+        "/instructor/settings",
+        data={"selection_mode": "weighted", "weight_factor": "2",
+              "scale_type": "table",
+              "scale_rows": "93 A\n90 A-\n0 F"},
+    )
+    record_calls(instructor, n=3)
+    instructor.post("/instructor/grades/compute")
+    page = instructor.get("/instructor/grades/").get_data(as_text=True)
+    assert "<strong>A</strong>" in page