Add lintlang (AI_LINTLANG) to External Plugins Catalog

[roli-lpci]

Fixes #8865

Proposed Changes

1. Add one row to .automation/plugins.yml for lintlang (AI_LINTLANG), a deterministic, offline linter for AI agent instructions, tool definitions, and prompt files, published as an external plugin at https://github.com/hermes-labs-ai/lintlang/tree/main/mega-linter-plugin-lintlang.
2. Add lintlang to .cspell.json, matching earlier catalog additions.

Generated tables in README.md and docs/plugins.md are left to .automation/build.py, as with previous catalog rows.

Descriptor: https://raw.githubusercontent.com/hermes-labs-ai/lintlang/main/mega-linter-plugin-lintlang/lintlang.megalinter-descriptor.yml

Verified end to end in oxsecurity/megalinter:v8 and oxsecurity/megalinter-python:v9.4.0: the plugin loader installs lintlang==0.5.3 at run time, a failing fixture makes MegaLinter exit 1, and a clean workspace exits 0.

Readiness Checklist

Author/Contributor

• Add entry to the CHANGELOG listing the change and linking to the corresponding issue (if appropriate) — not added, matching the earlier catalog rows in Add j2lint to plugins #5151 and Add fmlint (frontmatter linter) to plugins list #5257
• If documentation is needed for this change, has that been included in this pull request

Reviewing Maintainer

• Label as breaking if this is a large fundamental change
• Label as either automation, bug, documentation, enhancement, infrastructure, or performance

MegaLinter v10 compatibility

Reopening this existing catalog contribution after completing the requested v10 check. The two-file catalog diff is unchanged.

Tested on 5 September 2026 with ghcr.io/oxsecurity/megalinter-python:v10.1.0 (linux/amd64), image digest sha256:f12a40b0dd5ad2c9aa029dcf7d3a0a92182d05cacc32d37756e67c3446484acb.

The external plugin loader fetched the HTTPS descriptor and installed lintlang==0.5.3 at runtime.

Workspace	Selected files	Container exit
Clean and deliberately bad agent fixtures, plus unrelated package.json	The two agent YAML files; clean reported PASS, bad reported FAIL	1
Clean agent fixture plus unrelated package.json	Only the clean agent YAML file	0

This verifies the loader, installation, file selection, and exit behavior on the Python flavor of v10.1.0.

Reproduce the v10 check

Use the descriptor and fixtures from LintLang commit b525d910ac73b3c7d34c8e20ed9dc34786c2ca66.

In a scratch directory, copy clean_config.yaml to agent-clean.yaml and bad_tool_descriptions.yaml to agent-bad.yaml. Add an unrelated package.json containing {} and this .mega-linter.yml:

PLUGINS:
  - https://raw.githubusercontent.com/hermes-labs-ai/lintlang/b525d910ac73b3c7d34c8e20ed9dc34786c2ca66/mega-linter-plugin-lintlang/lintlang.megalinter-descriptor.yml
ENABLE_LINTERS:
  - AI_LINTLANG
VALIDATE_ALL_CODEBASE: true
LOG_LEVEL: INFO
PRINT_ALPACA: false
SHOW_ELAPSED_TIME: true

docker run --rm --platform linux/amd64   -v "$PWD:/tmp/lint:rw"   -e DEFAULT_WORKSPACE=/tmp/lint   ghcr.io/oxsecurity/megalinter-python@sha256:f12a40b0dd5ad2c9aa029dcf7d3a0a92182d05cacc32d37756e67c3446484acb

The first run exits 1. Move agent-bad.yaml outside the scratch directory and rerun; it exits 0. The unrelated metadata file is not selected in either run.