ci(tests): add cross-platform test workflow + fix drift surfaced by it

Enables the same 3-OS x 4-Python CI matrix that attune-rag uses,
gating every PR on ruff + pytest. Enabling CI surfaced four real
issues that had accumulated without test automation:

- engine.py: `Callable` used at line 580 with no import (F821).
  Runtime-crashable if _auto_detect_renderer was introspected
  before call. Added `from typing import Callable`.
- test_plugin_config.py: 15 dead tests validating a `plugin/`
  directory that was never created in this repo (monorepo-
  extraction carryover). Deleted.
- test_plugin_references.py: stale assertions expecting 6 MCP
  tools (reality: 10) and method-name/tool-name equality (dispatch
  intentionally renames 3). Rewrote to verify via the real
  dispatch table — the source of truth for MCP routing.
- test_transformers.py: unused `eng` local in
  test_auto_without_tty_falls_back_to_plain (F841). Removed.

Also adds a `[dev]` optional-dependencies extra so CI can do
`pip install -e .[dev]` without enumerating test tooling.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: silversurfer562

.github/workflows/tests.yml

@@ -0,0 +1,40 @@
+name: Tests
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: test (${{ matrix.os }}, ${{ matrix.python-version }})
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 15
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        python-version: ["3.10", "3.11", "3.12", "3.13"]
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - name: Set up Python
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+        with:
+          python-version: ${{ matrix.python-version }}
+          cache: pip
+
+      - name: Install with dev extra
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install -e ".[dev]"
+
+      - name: Run ruff
+        run: python -m ruff check src/ tests/
+
+      - name: Run tests
+        run: python -m pytest tests/ -v --tb=short

pyproject.toml

@@ -32,6 +32,12 @@ dependencies = [
 [project.optional-dependencies]
 rich = ["rich>=13.0.0"]
 plugin = ["mcp>=0.9.0"]
+dev = [
+    "pytest>=7.0",
+    "pytest-cov>=4.0",
+    "ruff>=0.4.0",
+    "mcp>=0.9.0",
+]
 
 [project.scripts]
 attune-help = "attune_help.cli:main"

src/attune_help/engine.py

@@ -9,6 +9,7 @@
 
 import logging
 import threading
+from collections.abc import Callable
 from pathlib import Path
 
 from attune_help.progression import populate_progressive

tests/test_engine.py

@@ -6,7 +6,6 @@
 from pathlib import Path
 
 import pytest
-
 from attune_help import HelpEngine, LocalFileStorage
 from attune_help.engine import _DEPTH_PROMPTS