steam-backlog-enforcer/prompts/TODO-pylint-to-ten.md

Session prompt: take pylint from 8.65 to 10.00

Paste everything below the line into a fresh Claude Code session started in ~/steam-backlog-enforcer.

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Take this repo's pylint score from 8.65/10 to a clean 10.00/10, without weakening the linter.

Why

The pre-commit pylint hook runs with --fail-under=8.0, so at 8.65 the repo passes its gate while carrying ~1600 findings. The threshold is hiding the debt rather than measuring it. The same job was done in ~/utils/crdt-sync on 2026-08-21 (8.58 -> 10.00); this repo has the identical shape of problem, only larger.

Measured on this machine, 2026-08-21, with ~/.cache/pre-commit/repo01lfw04p/py_env-python3/bin/pylint --rcfile=pyproject.toml steam_backlog_enforcer scripts:

category	count
missing-function-docstring	1061
use-implicit-booleaness-not-comparison-to-zero	121
missing-class-docstring	97
duplicate-code	66
use-implicit-booleaness-not-comparison	60
redefined-outer-name	42
protected-access	38
import-outside-toplevel	20

All 1158 missing-docstring findings are in steam_backlog_enforcer/tests/. That is ~72% of the total and the single highest-leverage fix. There are 150 test files.

Re-measure before you start and again at the end. The first run guards against the situation having changed; the second is the acceptance check.

Scope

In scope

1. Every pylint finding under steam_backlog_enforcer/ and scripts/.
2. Test docstrings — the bulk of the work.

Out of scope — do not touch

• --fail-under in .pre-commit-config.yaml. Do NOT raise it to hide a shortfall, and do NOT lower it. Leave it at 8.0; the score is what moves.
• pyproject.toml's [tool.pylint.messages_control] disable list. Adding a check to it is the failure mode this task exists to avoid.
• Anything under node_modules/, web/, or *.egg-info/.

The rule that decides the approach

Fix the underlying issue; do not suppress it. The repo blocks noqa and type: ignore outright via a pre-commit hook. Inline # pylint: disable= is permitted ONLY where the finding is a genuine false positive, and then it must be:

• scoped to the narrowest unit (prefer disable-next on the exact line over a file-level disable),
• placed on the line that actually triggers it (verify — a disable-next one line off silently does nothing and pylint reports useless-suppression),
• accompanied by a comment saying WHY the check is wrong here.

Ask before adding any suppression that is not clearly a false positive.

What worked in crdt-sync (copy this)

Writing 277 test docstrings by hand is slow and error-prone. Script the first draft, then review every one:

1. Parse each test file with ast, find every ClassDef/FunctionDef whose name starts with test_/Test and has no docstring.
2. Derive prose from the identifier — these test names are already sentences.
3. Insert at the anchor, not the first body statement. If the first statement is decorated (@staticmethod, @pytest.mark...), inserting at its lineno puts the docstring BETWEEN the decorator and its def and produces a syntax error. Anchor to min(lineno, *[d.lineno for d in decorator_list]).
4. Back the test tree up first (cp -a), run the suite immediately after, and ast.parse every touched file before trusting it.

A docstring that merely restates the test name adds nothing — after the generated pass, go back and improve the ones where the assertion says something the name does not.

Also expect

• use-implicit-booleaness-* (181 total): assert not x for assert x == {} / == [] / == 0 / == "". Mechanical, but check each — in a test, the explicit form sometimes asserts the TYPE too, which is worth keeping.
• redefined-outer-name (42): pytest fixture idiom. Usually a rename.
• protected-access (38): if the private member IS the thing under test, that is a legitimate scoped disable with a reason.
• duplicate-code (66): look for near-copy fakes/helpers across test modules. In crdt-sync two duplicated in-memory fakes merged into one class in conftest.py — that is the sanctioned home (a non-test_*.py module in a tests dir can trip the name-tests-test hook). Watch coverage when merging: the union class must still exercise every branch.

Gates

• python -m pytest -q --ignore=steam_backlog_enforcer/tests/test_mcp.py — 1288 passing is the baseline (measured 2026-08-21, ~63s). That count must hold.

  Read this before you think you broke something: a plain python -m pytest -q currently fails at COLLECTION with ModuleNotFoundError: No module named 'mcp.server.fastmcp'. This is pre-existing and NOT yours to fix. pyproject.toml declares mcp as an optional extra (mcp = ["mcp>=1.9,<2"]) served by a dedicated venv via scripts/setup_mcp.sh; the system interpreter has mcp 2.0.0, and the 2.x line removed mcp.server.fastmcp. Ignore that one module, do not "fix" the import, and do not touch the pin — mention it in your report and move on.

  Because that module is skipped, coverage reads 97.32%, not 100%. Do not chase the missing 2.68% and do not let a coverage gate mislead you into thinking your change caused it. What matters is that the number does not get WORSE.

• pre-commit run --files <changed> — must pass, including the noqa blocker.

• ruff format will reformat what you touch; re-run the suite after it, and do not let it reformat files this task never touched.

Done means

1. pylint --rcfile=pyproject.toml steam_backlog_enforcer scripts reports 10.00/10.
2. --fail-under is still 8.0 and the disable list is unchanged.
3. 1288 tests still passing (with test_mcp.py ignored, as above) and coverage no worse than the 97.32% baseline.
4. Every suppression you added is listed in the final report with its justification. If you could not reach 10.00 without a suppression the user would not accept, say so and report the real number instead.

REMOVE ME AFTER FINISH