perf(oxlint): return first found config for resolving config

[Sysix]

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[Sysix]

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• perf(oxlint): return first found config for resolving config #21055 👈 (View in Graphite)
• fix(oxlint): don't search for nested config outside base config #21051
• test(oxlint): add test for nested config with cwd #21050
• main

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[Copilot]

Pull request overview

This PR optimizes oxlint’s nested config discovery when walking ancestor directories by returning only the first config found per directory instead of collecting all possible config files.

Changes:

• Updated ancestor config discovery to use a single optional config per directory (early-return).
• Changed find_configs_in_directory from returning Vec<DiscoveredConfig> to Option<DiscoveredConfig>.

Comments suppressed due to low confidence (1)

apps/oxlint/src/config_loader.rs:72

• In discover_configs_in_ancestors, the “stop at base config” boundary relies on find_configs_in_directory returning the base config when it exists. After changing that helper to return only a single (first-found) config, a directory with multiple config files can cause the base config path to be missed, so the walk can continue past the intended root and also skip emitting a conflict error. Consider preserving multi-config discovery here (or explicitly detecting conflict + base-config presence) so ancestor traversal is correctly bounded and conflicts are still diagnosed.

            if let Some(config) = find_configs_in_directory(dir) {
                if config.path() == base_config_path {
                    // Stop if we've reached the base config file (e.g., root oxlintrc)
                    // to avoid duplicate loading and filling nested config with configs outside from the root config.
                    break;
                }
                config_paths.insert(config);
            }

[Copilot]

find_configs_in_directory now returns only the first matching config file (JSON → JSONC → TS) and stops checking the other filenames. This changes behavior from the previous implementation that discovered all config files in a directory, which is needed so load_many can detect and error on per-directory config conflicts (see config_conflict_diagnostic). With the new logic, a directory containing multiple config files will silently pick one and will no longer surface the conflict diagnostic during ancestor discovery, potentially applying the wrong config.