Embed question verification references

api/QuestionsApi/Controllers/QuestionsController.cs

@@ -323,6 +323,36 @@ public class QuestionsController : ControllerBase
         return Ok(new { upserted });
     }
 
+    [HttpPost("admin/references/bulk")]
+    [Authorize(Roles = "SUPER")]
+    public async Task<IActionResult> BulkUpdateReferences([FromBody] BulkQuestionReferencesRequest req)
+    {
+        if (req.Questions.Count == 0)
+            return BadRequest("questions required");
+
+        var externalIds = new HashSet<string>(StringComparer.Ordinal);
+        foreach (var update in req.Questions)
+        {
+            if (string.IsNullOrWhiteSpace(update.ExternalId))
+                return BadRequest("externalId required");
+            var externalId = update.ExternalId.Trim();
+            if (!externalIds.Add(externalId))
+                return BadRequest($"duplicate externalId: {externalId}");
+            var validation = QuestionValidator.ValidateReferences(update.References, required: true);
+            if (validation is not null)
+                return BadRequest($"{externalId}: {validation}");
+        }
+
+        var missing = await _questions.GetMissingExternalIdsAsync(externalIds);
+        if (missing.Count > 0)
+            return BadRequest($"unknown externalIds: {string.Join(", ", missing)}");
+
+        var updated = await _questions.UpdateReferencesByExternalIdAsync(req.Questions);
+        if (updated != req.Questions.Count)
+            return Conflict("one or more questions changed before references could be updated");
+        return Ok(new { updated });
+    }
+
     [HttpPut("{id}")]
     [Authorize(Roles = "SUPER")]
     public async Task<IActionResult> Update(string id, [FromBody] UpsertQuestionRequest req)

api/QuestionsApi/Models/BulkQuestionReferencesRequest.cs

@@ -0,0 +1,12 @@
+namespace QuestionsApi.Models;
+
+public class BulkQuestionReferencesRequest
+{
+    public List<QuestionReferencesUpdate> Questions { get; set; } = [];
+}
+
+public class QuestionReferencesUpdate
+{
+    public string ExternalId { get; set; } = "";
+    public List<QuestionReference> References { get; set; } = [];
+}

api/QuestionsApi/Models/Question.cs

@@ -25,6 +25,7 @@ public class Question
     public List<QuestionLab> Labs { get; set; } = [];
     public List<string> Media { get; set; } = [];
     public List<string> Tags { get; set; } = [];
+    public List<QuestionReference> References { get; set; } = [];
     public bool IsPublished { get; set; } = true;
     public DateTime CreatedUtc { get; set; } = DateTime.UtcNow;
     public DateTime UpdatedUtc { get; set; } = DateTime.UtcNow;
@@ -51,3 +52,13 @@ public class WrongAnswerFollowup
     public string CorrectChoiceId { get; set; } = "";
     public string TeachingPoint { get; set; } = "";
 }
+
+public class QuestionReference
+{
+    public string Title { get; set; } = "";
+    public string Publisher { get; set; } = "";
+    public string Url { get; set; } = "";
+    public string Supports { get; set; } = "";
+    public string AccessedOn { get; set; } = "";
+    public string Reviewer { get; set; } = "";
+}

api/QuestionsApi/Models/QuestionRequests.cs

@@ -29,6 +29,7 @@ public class UpsertQuestionRequest
     public List<QuestionLab> Labs { get; set; } = [];
     public List<string> Media { get; set; } = [];
     public List<string> Tags { get; set; } = [];
+    public List<QuestionReference> References { get; set; } = [];
     public bool IsPublished { get; set; } = true;
 }
 

api/QuestionsApi/Models/QuestionResponse.cs

@@ -21,6 +21,7 @@ public class QuestionResponse
     public List<QuestionLab> Labs { get; set; } = [];
     public List<string> Media { get; set; } = [];
     public List<string> Tags { get; set; } = [];
+    public List<QuestionReference> References { get; set; } = [];
 
     public static QuestionResponse FromModel(
         Question question,
@@ -56,7 +57,8 @@ public class QuestionResponse
             QuestionElo = questionElo,
             Labs = question.Labs,
             Media = question.Media,
-            Tags = question.Tags
+            Tags = question.Tags,
+            References = question.References
         };
     }
 

api/QuestionsApi/README.md

@@ -11,6 +11,7 @@ STEP-style question bank service for study games and clients.
 - `GET /api/questions/{id}` Get one question.
 - `POST /api/questions` Create question (SUPER only).
 - `POST /api/questions/bulk` Upsert questions by `externalId` (SUPER only).
+- `POST /api/questions/admin/references/bulk` Update only embedded verification references by `externalId` (SUPER only).
 - `PUT /api/questions/{id}` Update question (SUPER only).
 - `DELETE /api/questions/{id}` Delete question (SUPER only).
 - `POST /api/question-reports` Submit a categorized question report (USER or SUPER).
@@ -39,7 +40,10 @@ extra distractors to existing questions.
 Search clients that set `supportsChoicePools: true` receive each complete
 choice pool. Older clients receive five server-selected choices that always
 include the correct answer. Published questions require 5-20 unique choices,
-an explanation for every choice, and a follow-up for every incorrect choice.
+an explanation for every choice, a follow-up for every incorrect choice, and at
+least one embedded authoritative verification reference. Legacy published
+questions without references remain readable but must add references before a
+future authoring update.
 
 - `GET /readyz` verifies MongoDB connectivity for readiness checks.
 - `GET /metrics` exposes Prometheus-format service and reconciliation metrics.

api/QuestionsApi/Services/QuestionStore.cs

@@ -151,6 +151,32 @@ public class QuestionStore
         return systems.Where(s => !string.IsNullOrWhiteSpace(s)).OrderBy(s => s).ToList();
     }
 
+    public async Task<List<string>> GetMissingExternalIdsAsync(IEnumerable<string> externalIds)
+    {
+        var requested = externalIds.Distinct(StringComparer.Ordinal).ToList();
+        var existing = await _col.Find(Builders<Question>.Filter.In(q => q.ExternalId, requested))
+            .Project(q => q.ExternalId)
+            .ToListAsync();
+        return requested.Except(existing, StringComparer.Ordinal).OrderBy(id => id).ToList();
+    }
+
+    public async Task<int> UpdateReferencesByExternalIdAsync(IEnumerable<QuestionReferencesUpdate> updates)
+    {
+        var now = DateTime.UtcNow;
+        var writes = updates.Select(update =>
+            new UpdateOneModel<Question>(
+                Builders<Question>.Filter.Eq(question => question.ExternalId, update.ExternalId.Trim()),
+                Builders<Question>.Update
+                    .Set(question => question.References, NormalizeReferences(update.References))
+                    .Set(question => question.UpdatedUtc, now)))
+            .ToList();
+        if (writes.Count == 0)
+            return 0;
+
+        var result = await _col.BulkWriteAsync(writes, new BulkWriteOptions { IsOrdered = true });
+        return (int)result.MatchedCount;
+    }
+
     private static Question FromRequest(UpsertQuestionRequest req) => new()
     {
         ExternalId = req.ExternalId.Trim(),
@@ -169,6 +195,18 @@ public class QuestionStore
         Labs = req.Labs,
         Media = req.Media,
         Tags = req.Tags.Where(t => !string.IsNullOrWhiteSpace(t)).Select(t => t.Trim()).Distinct(StringComparer.OrdinalIgnoreCase).ToList(),
+        References = NormalizeReferences(req.References),
         IsPublished = req.IsPublished
     };
+
+    private static List<QuestionReference> NormalizeReferences(IEnumerable<QuestionReference>? references) =>
+        (references ?? []).Select(reference => new QuestionReference
+        {
+            Title = reference.Title.Trim(),
+            Publisher = reference.Publisher.Trim(),
+            Url = reference.Url.Trim(),
+            Supports = reference.Supports.Trim(),
+            AccessedOn = reference.AccessedOn.Trim(),
+            Reviewer = reference.Reviewer.Trim()
+        }).ToList();
 }

api/QuestionsApi/Services/QuestionValidator.cs

@@ -1,4 +1,5 @@
 using QuestionsApi.Models;
+using System.Globalization;
 
 namespace QuestionsApi.Services;
 
@@ -52,6 +53,45 @@ public static class QuestionValidator
         if (string.IsNullOrWhiteSpace(req.System)) return "system required";
         if (string.IsNullOrWhiteSpace(req.Discipline)) return "discipline required";
         if (req.Difficulty is < 1 or > 5) return "difficulty must be between 1 and 5";
+        var referenceValidation = ValidateReferences(req.References, req.IsPublished);
+        if (referenceValidation is not null) return referenceValidation;
+        return null;
+    }
+
+    public static string? ValidateReferences(IReadOnlyCollection<QuestionReference>? references, bool required)
+    {
+        if (references is null)
+            return "verification references must be an array";
+        if (required && references.Count == 0)
+            return "published questions require at least one verification reference";
+        if (references.Count > 20)
+            return "questions support at most twenty verification references";
+
+        var urls = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+        foreach (var reference in references)
+        {
+            if (string.IsNullOrWhiteSpace(reference.Title)
+                || string.IsNullOrWhiteSpace(reference.Publisher)
+                || string.IsNullOrWhiteSpace(reference.Url)
+                || string.IsNullOrWhiteSpace(reference.Supports)
+                || string.IsNullOrWhiteSpace(reference.AccessedOn)
+                || string.IsNullOrWhiteSpace(reference.Reviewer))
+                return "verification reference fields are required";
+
+            var url = reference.Url.Trim();
+            if (!Uri.TryCreate(url, UriKind.Absolute, out var uri) || uri.Scheme != Uri.UriSchemeHttps)
+                return "verification reference urls must be absolute HTTPS urls";
+            if (!urls.Add(url))
+                return "verification reference urls must be unique within a question";
+            if (!DateOnly.TryParseExact(
+                    reference.AccessedOn.Trim(),
+                    "yyyy-MM-dd",
+                    CultureInfo.InvariantCulture,
+                    DateTimeStyles.None,
+                    out _))
+                return "verification reference accessedOn must use YYYY-MM-DD";
+        }
+
         return null;
     }
 }