[FIX] Use correct primary key field in prompt count subquery

[harini-venkataraman]

ToolStudioPrompt uses prompt_id as its primary key, not id. Count("id") causes FieldError on the list endpoint (500).

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Can this PR break any existing features. If yes, please list possible items. If no, please explain why. (PS: Admins do not merge the PR without this section filled)

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Quality Gate passed

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[greptile-apps]

Greptile Summary

This PR fixes a FieldError that caused HTTP 500 on the tool list endpoint by correcting the field name in a Django ORM Count() annotation from "id" (which does not exist on ToolStudioPrompt) to "prompt_id" (the model's actual primary key). The change is minimal, targeted, and fully resolves the crash.

• Root cause confirmed: ToolStudioPrompt declares prompt_id = models.UUIDField(primary_key=True, ...) and has no id field — Count("id") raised a FieldError at runtime on every list request.
• Fix is correct: prompt_id is a NOT NULL UUID primary key, so Count("prompt_id") is semantically equivalent to COUNT(*) and correctly counts all prompts belonging to each tool.
• Scope is narrow: only the subquery used in the list action of PromptStudioCoreView is touched; no serializers, permissions, migrations, or other query paths are affected.

Confidence Score: 5/5

Safe to merge — single-line fix resolves a confirmed HTTP 500 with no side effects.

The change is a minimal, well-understood correction to a Django ORM field reference. The ToolStudioPrompt model clearly declares prompt_id as its primary key with no id field, making the original Count("id") a definite FieldError at runtime. Count("prompt_id") is semantically correct since the field is NOT NULL. No migrations, serializers, permissions, or other endpoints are touched. Only one P2 style note remains, which does not affect correctness.

No files require special attention — the single changed file contains only a correct, targeted fix.

Important Files Changed

Filename	Overview
backend/prompt_studio/prompt_studio_core_v2/views.py	Single-line fix: Count("id") → Count("prompt_id") in prompt count subquery — resolves FieldError (HTTP 500) on list endpoint; fix is correct and non-breaking

Sequence Diagram

sequenceDiagram
    participant Client
    participant PromptStudioCoreView
    participant DB as Database

    Client->>PromptStudioCoreView: GET /api/v2/tool-studio/ (list)
    PromptStudioCoreView->>DB: CustomTool.objects.for_user(user)
    Note over PromptStudioCoreView,DB: Subquery for prompt count per tool
    PromptStudioCoreView->>DB: ToolStudioPrompt.objects<br/>.filter(tool_id=OuterRef("pk"))<br/>.values("tool_id")<br/>.annotate(cnt=Count("prompt_id"))<br/>.values("cnt")
    Note over PromptStudioCoreView,DB: BEFORE: Count("id") → FieldError (HTTP 500)<br/>AFTER: Count("prompt_id") → correct count
    DB-->>PromptStudioCoreView: annotated queryset (_prompt_count per tool)
    PromptStudioCoreView-->>Client: 200 OK — serialized tool list with prompt counts

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Prompt To Fix All With AI

This is a comment left during a code review.
Path: backend/prompt_studio/prompt_studio_core_v2/views.py
Line: 118

Comment:
**Consider using `Count("*")` for clarity**

The fix is correct — `prompt_id` is the non-null primary key so `Count("prompt_id")` is semantically identical to `COUNT(*)`. However, using `Count("*")` makes the intent explicit ("count every row in the group") and avoids any future confusion if a reader wonders why a specific field is named here rather than a simple row count.

```suggestion
                .annotate(cnt=Count("*"))
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "[FIX] Use correct primary key field in p..." | Re-trigger Greptile}

[greptile-apps]

Consider using Count("*") for clarity

The fix is correct — prompt_id is the non-null primary key so Count("prompt_id") is semantically identical to COUNT(*). However, using Count("*") makes the intent explicit ("count every row in the group") and avoids any future confusion if a reader wonders why a specific field is named here rather than a simple row count.

Suggested change

	.annotate(cnt=Count("prompt_id"))
	.annotate(cnt=Count("*"))

Prompt To Fix With AI

This is a comment left during a code review.
Path: backend/prompt_studio/prompt_studio_core_v2/views.py
Line: 118

Comment:
**Consider using `Count("*")` for clarity**

The fix is correct — `prompt_id` is the non-null primary key so `Count("prompt_id")` is semantically identical to `COUNT(*)`. However, using `Count("*")` makes the intent explicit ("count every row in the group") and avoids any future confusion if a reader wonders why a specific field is named here rather than a simple row count.

```suggestion
                .annotate(cnt=Count("*"))
```

How can I resolve this? If you propose a fix, please make it concise.

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}