fix(cli): merge root and sub-package lint configs for vp lint

[kazupon]

Summary

Fixes vp lint ignoring sub-package ignorePatterns (and other lint config overrides) when running in a monorepo sub-package.

resolves #997

Root Cause

vp lint always resolved the vite config from the workspace root, regardless of the current working directory.

When a sub-package defined its own vite.config.ts with lint.ignorePatterns, it was never read, oxlint only received the root's config via -c.

Fix

When cwd differs from the workspace root and the sub-package has its own vite.config.ts, both configs are resolved and merged.

The root config serves as the base and the sub-package config overrides specific fields (plugins are unioned, rules/options are shallow-merged with sub-package priority, ignorePatterns are fully overridden by sub-package, overrides are concatenated).

The merged result is written to a fixed cache path (node_modules/.cache/vite-plus/merged-lint-config.json) and passed to oxlint via -c.

Bug flow — sub-package config ignored

sequenceDiagram
    participant User as User (in packages/some-package/)
    participant Rust as vp lint (Rust CLI)
    participant JS as resolveUniversalViteConfig
    participant Vite as Vite resolveConfig
    participant Oxlint as oxlint

    User->>Rust: vp lint
    Rust->>Rust: workspace_path = /root (always)
    Rust->>JS: resolveUniversalViteConfig("/root")
    JS->>Vite: resolveViteConfig("/root")
    Vite-->>JS: configFile: /root/vite.config.ts
    Note over JS: lint: { plugins: ["import"],<br/>rules: { "import/no-commonjs": "error" } }<br/>Warn: No ignorePatterns

    JS-->>Rust: { configFile: "/root/vite.config.ts", lint }
    Rust->>Oxlint: oxlint -c /root/vite.config.ts
    Note over Oxlint: Reads root config only<br/>Sub-package ignorePatterns never seen
    Oxlint-->>User: NG: import/no-commonjs error on fixture files

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Fix flow — configs merged

sequenceDiagram
    participant User as User (in packages/some-package/)
    participant Rust as vp lint (Rust CLI)
    participant JS as resolveUniversalViteConfig
    participant Vite as Vite resolveConfig
    participant Oxlint as oxlint

    User->>Rust: vp lint
    Rust->>Rust: workspace_path = /root, cwd = /root/packages/some-package
    Rust->>JS: resolveUniversalViteConfig(JSON)
    Note over Rust: {"workspacePath": "/root",<br/>"cwd": "/root/packages/some-package"}

    JS->>Vite: resolveViteConfig("/root")
    Vite-->>JS: rootLint: { plugins, rules }
    JS->>Vite: resolveViteConfig("/root/packages/some-package")
    Vite-->>JS: cwdLint: { ignorePatterns, options }

    JS->>JS: mergeLintConfig(rootLint, cwdLint)
    Note over JS: merged: { plugins, rules,<br/>ignorePatterns, options }

    JS->>JS: Write merged config to<br/>node_modules/.cache/vite-plus/<br/>merged-lint-config.json
    JS-->>Rust: { configFile: "merged-lint-config.json", lint }

    Rust->>Oxlint: oxlint -c merged-lint-config.json
    Note over Oxlint: Reads merged config<br/>ignorePatterns excludes fixtures<br/>Root rules still apply
    Oxlint-->>User: OK: 0 errors (fixtures excluded)

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Fix

When cwd differs from the workspace root and the sub-package has its own vite.config.ts, both configs are resolved and merged.

The root config serves as the base and the sub-package config overrides specific fields (plugins are unioned, rules/options are shallow-merged with sub-package priority, ignorePatterns are fully overridden by sub-package, overrides are concatenated).

The merged result is written to a fixed cache path (node_modules/.cache/vite-plus/merged-lint-config.json) and passed to oxlint via -c.

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[kazupon]

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Keep fmt pointed at a config that contains fmt settings

When cwd has its own vite.config and mergedLint is produced, this branch returns configFile: mergedConfigPath, but mergedConfigPath is a JSON file written from mergedLint only. The Rust resolver reuses configFile for both vp lint and vp fmt, so vp fmt/vp check in that sub-package will be run with a config file that lacks fmt fields, causing formatter options from root/cwd vite.config to be ignored (or rejected, depending on parser behavior).

Useful? React with 👍 / 👎.

[fengmk2]

I think the configuration handling logic for lint and fmt should be considered clearly on the oxlint and oxfmt side first.

[leaysgur]

I think the configuration handling logic for lint and fmt should be considered clearly on the oxlint and oxfmt side first.

Yes, and I understand that in order to do that, we need to decide how to handle the config files in Vite+ first. 🐣

In any case, I don't think we can make any code changes at this moment. Also, this approach won't be aligned with the LSP.

[cktang88]

Oxlint oxfmt handles it like so https://oxc.rs/docs/guide/usage/linter/nested-config.html