fviolence/searxng-query-corrector repository overview

⁠Custom SearXNG⁠ query-corrector shim

A conservative compatibility service between the custom SearXNG query_corrector engine and a self-hosted LanguageTool server.

⁠Behavior

The shim:

• accepts POST /v1/correct with query and optional language;
• calls LanguageTool's POST /v2/check;
• considers only matches with rule.issueType == "misspelling";
• rejects case-only changes, technical-looking tokens, SearXNG query-syntax tokens, unsafe control characters, whitespace replacements by default, excessive edit distances, genuinely overlapping edits, and queries requiring too many edits;
• deduplicates repeated LanguageTool matches that refer to the same source span;
• caches LanguageTool-supported languages through /readyz and falls back to auto-detection for unsupported language codes;
• permits the zero-width joiner and non-joiner characters that SearXNG accepts for scripts that require them;
• returns {"correction": null} whenever it cannot make a conservative correction;
• exposes /healthz and /readyz.

⁠Chosen LanguageTool image

image: docker.io/erikvl87/languagetool:6.8

⁠Compose integration

Merge the languagetool and query-corrector services from compose.example.yml into the existing SearXNG Compose file.

No host ports are required. Docker Compose DNS makes these internal addresses available:

• http://languagetool:8010
• http://query-corrector:8000

Then configure SearXNG:

use_default_settings: true

engines:
  - name: query corrector
    base_url: http://query-corrector:8000
    enable_http: true
    timeout: 1.0
    inactive: false
    disabled: false

The engine rejects plain HTTP unless enable_http: true is set. This is appropriate for the private Docker network shown above; use HTTPS for a remote service.

The bundled SearXNG engine timeout is 250 ms, so start with 1.0 second for this LanguageTool sidecar and tune after observing real latency.

Keep LANGUAGETOOL_TIMEOUT below the SearXNG engine timeout so the shim can return cleanly before SearXNG cancels its request. The initial LanguageTool request and the optional language=auto retry share this single timeout budget.

The Docker health check deliberately calls /readyz, not /healthz. The container is therefore marked unhealthy while LanguageTool is unavailable, even when the shim process itself is still serving requests.

⁠Environment variables

GitHub repo: https://github.com/fviolence/query-corrector⁠