| 1 | # Python Playbook v1 |
| 2 | |
| 3 | ## Purpose |
| 4 | Dedicated playbook for robust Python usage in automation, data processing, and tooling tasks. |
| 5 | |
| 6 | ## Scope |
| 7 | - Runtime and dependency discipline |
| 8 | - Script-to-module evolution |
| 9 | - Data parsing and encoding safety |
| 10 | - Testability and maintainability |
| 11 | |
| 12 | ## Evidence-Based Working Format |
| 13 | - Fact: capture current failure mode or maintainability pain. |
| 14 | - Hypothesis: define expected improvement from change. |
| 15 | - Check: validate with minimal deterministic run and tests. |
| 16 | - Decision criterion: success/failure thresholds before adoption. |
| 17 | - Confidence mark: explicit certainty level. |
| 18 | |
| 19 | ## Core Contracts |
| 20 | - Keep environment reproducible (venv/lock policy documented). |
| 21 | - Make input/output contracts explicit. |
| 22 | - Isolate pure transformation logic from side effects. |
| 23 | - Use explicit encoding and locale assumptions. |
| 24 | |
| 25 | ## Code Quality Contracts |
| 26 | - Prefer typed boundaries where it reduces ambiguity. |
| 27 | - Keep modules small and single-purpose. |
| 28 | - Treat exceptions as contract signals, not hidden control flow. |
| 29 | - Avoid global mutable state in reusable scripts. |
| 30 | |
| 31 | ## Data and Parsing Contracts |
| 32 | - Validate schema assumptions early. |
| 33 | - Handle malformed data with clear error paths. |
| 34 | - Keep regex/parsing logic test-covered. |
| 35 | - Preserve provenance metadata when transforming datasets. |
| 36 | |
| 37 | ## Testing Contracts |
| 38 | - Unit-test core parsing and transformation functions. |
| 39 | - Add integration tests for IO-heavy workflows. |
| 40 | - Keep fixture sets for edge cases and regressions. |
| 41 | - Track flaky behavior and remove nondeterminism sources. |
| 42 | |
| 43 | ## Metrics |
| 44 | - Script failure rate in routine runs. |
| 45 | - Mean time to diagnose Python task failures. |
| 46 | - Regression frequency after parser changes. |
| 47 | - Time from ad-hoc script to maintainable module. |
| 48 | |
| 49 | ## Revisit Triggers |
| 50 | - Repeated encoding or dependency issues. |
| 51 | - Scripts growing beyond maintainable size. |
| 52 | - Frequent runtime surprises from implicit assumptions. |
| 53 | |
| 54 | |