Platform selection bug: darwin-arm64 extensions served instead of linux-x64 due to alphabetical sorting

Bug Description

When using the /api/vscode/{publisher}/{extension}/latest endpoint (introduced in v2.4.0), the marketplace incorrectly serves darwin-arm64 extension variants instead of the appropriate platform-specific versions (e.g., linux-x64) due to alphabetical sorting of platform names.

Root Cause

The issue is in the ByVersion.Less() method in /storage/storage.go:

if vs[i].Version == vs[j].Version {
    return vs[i].TargetPlatform < vs[j].TargetPlatform
}

When multiple platform variants exist for the same semantic version (e.g., 2.36.4@darwin-arm64, 2.36.4@linux-x64), they are sorted alphabetically by platform string. Since "darwin-arm64" < "linux-x64" alphabetically, darwin-arm64 versions are always selected first when using IncludeLatestVersionOnly.

Impact

• Extensions fail to install in VS Code/code-server running on Linux platforms
• Affects all extensions that have multiple platform-specific variants
• Introduced in v2.4.0 when the new /latest endpoint started being used by VS Code

Example Logs

Expected behavior (linux-x64 environment should get linux-x64 variant):

ComputeTargetPlatform: linux-x64
2025-09-20 09:42:42.565 [debu] GET /files/hashicorp/terraform/2.36.4@linux-x64/hashicorp.terraform-2.36.4@linux-x64.vsix

Actual behavior (linux-x64 environment incorrectly gets darwin-arm64 variant):

ComputeTargetPlatform: linux-x64
2025-09-20 09:42:40.247 [debu] GET /files/hashicorp/terraform/2.36.4@darwin-arm64/extension/package.json

Environment

• code-marketplace version: v2.4.0
• VS Code/code-server: 1.104.0
• Platform: Linux x64 containers
• Extensions affected: Any extension with multiple platform variants (e.g., HashiCorp Terraform)

Proposed Solutions

1. Platform-aware filtering: Filter versions by the requesting client's target platform before sorting
2. Universal version priority: Prioritize universal platform versions when available
3. Platform preference order: Define a logical platform ordering instead of alphabetical (e.g., prefer common platforms like linux-x64 over darwin-arm64)
4. Client platform detection: Extract target platform from request headers or query parameters

Reproduction Steps

1. Set up code-marketplace v2.4.0
2. Upload an extension with multiple platform variants (e.g., versions for both linux-x64 and darwin-arm64)
3. Make a request to /api/vscode/{publisher}/{extension}/latest from a linux-x64 environment
4. Observe that darwin-arm64 variant is returned instead of linux-x64

Workaround

Temporarily downgrade to v2.3.1 or modify the version sorting logic to prioritize the appropriate platform for your environment.