fix: DSA sheet progress never persists — accept object completedTopics shape

[vedant7007]

Closes #1727

Problem

saveProgress rejected the real payload with 400:

if (completedTopics !== undefined && !Array.isArray(completedTopics)) { /* 400 "must be an array" */ }

The frontend sends completedTopics as an object/map ({ "0-0-0": true }), and so do the Zod validator (z.record(z.string(), z.boolean())), the Mongoose schema ({ type: Object }), resetProgress ({}), and the import util. !Array.isArray({...}) is true, so every save returned 400 and the frontend .catch swallowed it — progress lived only in localStorage and was lost across devices / on cache clear.

Fix

Validate completedTopics as a plain object (reject arrays/null) to match the rest of the system.

Testing

• node --check on the changed controller.

Contributing as part of Elite Coders Summer of Code (ECSoC 2026).

Summary

• Fixed saveProgress validation for completedTopics.
• The controller now accepts non-null plain objects, such as { "0-0-0": true }.
• The controller rejects arrays and null values.
• Updated the validation error message.
• Verified syntax with node --check.

[coderabbitai]

📝 Walkthrough

Walkthrough

The progress controller now accepts completedTopics object maps instead of arrays. It rejects null values and arrays, and updates the validation error message.

Changes

Progress validation

Layer / File(s)	Summary
Completed topics validation backend/controllers/userSheetProgressController.js	saveProgress now accepts non-null, non-array objects for completedTopics and returns an object-specific validation error for invalid values.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Possibly related PRs

• Canopus-Labs/PrepPilot#1565: Modifies progress data handling in userSheetProgressController.js.
• Canopus-Labs/PrepPilot#1619: Modifies concurrent progress saving in saveProgress.
• Canopus-Labs/PrepPilot#1621: Modifies completedTopics validation in the same controller.

Suggested labels: good-backend, level:beginner

Suggested reviewers: karanunique

🚥 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 clearly identifies the completedTopics shape correction that fixes DSA sheet progress persistence.
Linked Issues check	✅ Passed	The change aligns controller validation with issue #1727 by accepting object completedTopics values and rejecting null or array values.
Out of Scope Changes check	✅ Passed	The changes are limited to completedTopics validation and its error message, which directly supports issue #1727.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@backend/controllers/userSheetProgressController.js`:
- Around line 63-71: Strengthen the completedTopics validation in the user sheet
progress controller to require a plain object and boolean values for every
property, matching the contract enforced by ValidateUserSheetProgress. Reject
non-plain objects and any entry whose value is not boolean before persisting the
record, while preserving the existing 400 response.

🪄 Autofix

Fix all unresolved CodeRabbit comments on this PR:

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

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: f3981c68-c780-418a-ac3b-4a331ec7ad11

📥 Commits

Reviewing files that changed from the base of the PR and between a8a7be0 and e2d6a03.

📒 Files selected for processing (1)

• backend/controllers/userSheetProgressController.js

[coderabbitai]

🗄️ Data Integrity & Integration | 🟠 Major | ⚡ Quick win

Validate completedTopics values against the record contract.

This check accepts any non-null, non-array object. For example, { "0-0-0": "true" } passes validation, but backend/Input_validators/ValidateUserSheetProgress.js:5-10 requires string keys with boolean values. Validate that the value is a plain object and that every property value is boolean before persisting it.

Proposed fix

   if (
     completedTopics !== undefined &&
-    (typeof completedTopics !== "object" ||
-      completedTopics === null ||
-      Array.isArray(completedTopics))
+    (completedTopics === null ||
+      typeof completedTopics !== "object" ||
+      Array.isArray(completedTopics) ||
+      Object.values(completedTopics).some(
+        (value) => typeof value !== "boolean"
+      ))
   ) {
     return res.status(400).json({
       success: false,
-      error: "Invalid completedTopics field, must be an object",
+      error: "Invalid completedTopics field, must be an object with boolean values",
     });
   }

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@backend/controllers/userSheetProgressController.js` around lines 63 - 71,
Strengthen the completedTopics validation in the user sheet progress controller
to require a plain object and boolean values for every property, matching the
contract enforced by ValidateUserSheetProgress. Reject non-plain objects and any
entry whose value is not boolean before persisting the record, while preserving
the existing 400 response.

[KaranUnique]

@vedant7007 address the coderabbit suggestions