Issue Review: cloudflare/workers-sdk#10726

Summary

wrangler d1 create (and other resource creation commands) offer to add bindings to wrangler.jsonc but don't check if a binding with the same name/resource already exists, resulting in duplicate binding errors.

Findings

• Created: 2025-09-22
• Updated: 2025-09-23
• Version: Wrangler 4.38.0 → 4.60.0 (current)
• Component: Wrangler - config patching for resource creation commands
• Labels: bug, d1
• Comments: 2 (both from Cloudflare maintainers)

Key Evidence

• Valid bug identified by maintainer: @petebacondarwin confirmed this is a bug in PR #10414's logic, not specific to D1 - affects all resource creation commands (KV, R2, etc.)
• Root cause identified: The createdResourceConfig() function in packages/wrangler/src/utils/add-created-resource-config.ts calls experimental_patchConfig() with isArrayInsertion=true, which always appends new array items without checking for existing bindings with the same name
• No fix found: Searched for related PRs and changelog entries - no evidence of a fix being merged
• Reproduction provided: Reporter provided a clear minimal reproduction at https://github.com/irvinebroque/workers-for-platforms-example/pull/1/files
• Common pattern affected: Users often add binding stubs with empty IDs that they later fill in - this workflow is now broken

Technical Details

The issue occurs in the add-created-resource-config.ts file which handles all resource creation commands:

1. When creating a resource (D1, KV, R2, etc.), Wrangler offers to update wrangler.jsonc
2. If the user accepts, it calls experimental_patchConfig() with the new binding
3. experimental_patchConfig() uses isArrayInsertion=true which appends to the array without checking existing entries
4. If a binding with the same name already exists (common when users have pre-defined binding stubs with empty IDs), the config ends up with duplicate bindings
5. This causes a validation error: "Binding X assigned to multiple Y bindings"

Fix suggestion: Before inserting, the code should check if a binding with the same name already exists and either:

1. Update the existing binding's ID/properties instead of creating a new one
2. Prompt the user about the duplicate and ask how to proceed

Recommendation

Status: KEEP OPEN

Reasoning: This is a confirmed, reproducible bug affecting a common workflow. The root cause is clearly identified in the add-created-resource-config.ts utility, and a maintainer has acknowledged it. No fix has been merged since the issue was reported 4 months ago.

Action: Keep open for engineering to fix. The fix should check for existing bindings by name before inserting and either update them or prompt the user.

Suggested Comment

N/A - Issue is valid and should remain open for a fix.