fix: pass pre-read content to bypass fs.existsSync for WSL agent configs

[shanevcantwell]

Summary

• Pass pre-read content from overrideAssistantFile through the PackageIdentifier in LocalProfileLoader, reusing the content bypass added to RegistryClient in PR fix: pass pre-read content to RegistryClient for WSL compatibility #9739
• Check for pre-read content before the fs.existsSync gate in doLoadConfig, preventing fallback to the deprecated JSON config loader when the YAML path can't be resolved cross-filesystem

Context

When VS Code runs on Windows host with a WSL remote workspace (extensionKind: ["ui", "workspace"]), selecting an agent config from .continue/agents/ fails with:

Failed to parse config.json: Error: ENOENT: no such file or directory, open 'C:\Users\<user>\.continue\config.json'

localPathOrUriToPath can't resolve vscode-remote:// URIs to local paths on the Windows host, so fs.existsSync returns false, falling through to the deprecated JSON loader. The content is already available in memory — it just wasn't being passed through.

Same class of issue as #6242, #7810 (fixed in #9739) and #9661 (fixed in #9679).

Fixes #10450

Test plan

• New unit tests: LocalProfileLoader passes content in packageIdentifier for override files
• New unit tests: doLoadConfig uses YAML loading (not JSON fallback) when pre-read content is available
• All 1654 existing core tests pass
• All 291 config-yaml package tests pass
• Manual: select agent config from .continue/agents/ in WSL remote workspace

🤖 Generated with Claude Code

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Summary by cubic

Pass pre-read YAML content from override agent files to the config loader to avoid fs.existsSync checks for vscode-remote URIs. This fixes agent config selection in VS Code on Windows with a WSL remote workspace.

• Bug Fixes
  • LocalProfileLoader includes overrideAssistantFile.content in PackageIdentifier to reuse the content bypass path.
  • doLoadConfig checks for pre-read content before fs.existsSync and uses the YAML loader when present, avoiding fallback to the deprecated JSON loader when paths aren’t resolvable across Windows/WSL.

^{Written for commit f9714fe. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 4 files