RSPEED-2477: Deduplicate logging setup across entry point, log utility, and uvicorn runner

[major]

Description

PRs #1201 and #1202 fixed TTY-aware logging in two places and log-level resolution in three places, leaving identical logic copy-pasted across lightspeed_stack.py, log.py, and runners/uvicorn.py.

This extracts two shared functions into log.py:

• resolve_log_level() — reads env var, validates, falls back to INFO (was in 3 files)
• create_log_handler() — TTY → RichHandler, non-TTY → StreamHandler (was in 2 files)

The hardcoded format string moves to DEFAULT_LOG_FORMAT in constants.py.

get_logger() signature is unchanged — zero impact on the 72 modules that import it. lightspeed_stack.py keeps its own basicConfig(force=True) call since root logger config is entry-point-specific.

Type of change

• Refactor
• Unit tests improvement

Tools used to create PR

• Assisted-by: Claude

Related Tickets & Documents

• Related Issue: RSPEED-2477
• Related PRs: RSPEED-2471: Use plain log handler in non-TTY environments #1201, RSPEED-2472: Fix uvicorn ignoring LIGHTSPEED_STACK_LOG_LEVEL env var #1202

Checklist before requesting a review

• I have performed a self-review of my code.
• PR has passed all pre-merge test jobs.
• If it is a core feature, I have added thorough tests.

Testing

• uv run make test-unit — 1500 tests pass (86% coverage)
• uv run make verify — all linters pass (black, pylint, pyright, ruff, docstyle, mypy)
• New tests for resolve_log_level() (parametrized levels, invalid fallback, unset default)
• New tests for create_log_handler() (TTY → RichHandler, non-TTY → StreamHandler, format verification)

Summary by CodeRabbit

• Refactor

  • Centralized logging setup logic into dedicated utility functions for improved consistency across the application.
  • Enhanced log level validation with fallback to default values when invalid inputs are provided.

• Tests

  • Added comprehensive test coverage for new logging utilities, including handler selection based on terminal detection.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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Review profile: CHILL

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📥 Commits

Reviewing files that changed from the base of the PR and between aa48185 and bf2ccce.

📒 Files selected for processing (6)

• src/constants.py
• src/lightspeed_stack.py
• src/log.py
• src/runners/uvicorn.py
• tests/unit/runners/test_uvicorn_runner.py
• tests/unit/test_log.py

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Walkthrough

The PR centralizes logging configuration by introducing utility functions in the log module and constants for log format, removing duplicated log level resolution logic from individual modules and creating a single source of truth for logging setup.

Changes

Cohort / File(s)	Summary
Logging Configuration Constants src/constants.py	Added DEFAULT_LOG_FORMAT constant defining plain-text log format for non-TTY environments.
Centralized Logging Utilities src/log.py	Introduced resolve_log_level() to read and validate LIGHTSPEED_STACK_LOG_LEVEL_ENV_VAR with fallback to DEFAULT_LOG_LEVEL; introduced create_log_handler() to return RichHandler for TTY or StreamHandler with DEFAULT_LOG_FORMAT for non-TTY; updated get_logger() to use these utilities.
Logging Refactoring src/lightspeed_stack.py, src/runners/uvicorn.py	Replaced manual environment-based log level parsing and handler creation with calls to resolve_log_level() and create_log_handler(); removed local _resolve_log_level() from uvicorn.py.
Test Updates tests/unit/test_log.py, tests/unit/runners/test_uvicorn_runner.py	Expanded test coverage for resolve_log_level() and create_log_handler() with parameterized cases for log levels, TTY detection, and fallback behavior; updated imports to use centralized utilities instead of local helpers.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• RSPEED-2471: Use plain log handler in non-TTY environments #1201: Modifies logger initialization to select RichHandler for TTY and StreamHandler for non-TTY with the same log format pattern
• RSPEED-2472: Fix uvicorn ignoring LIGHTSPEED_STACK_LOG_LEVEL env var #1202: Changes uvicorn runner log level acquisition from local _resolve_log_level() to centralized resolve_log_level() function
• RSPEED-2437: Add configurable log level and unify logging #1148: Modifies project logging infrastructure through constants and log utility centralization with environment-driven configuration

Suggested labels

ok-to-test

Suggested reviewers

• jrobertboos
• tisnik

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically summarizes the main change: deduplicating logging setup logic across three locations. It is concise, directly related to the core purpose of the PR, and uses a ticket reference for traceability.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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[tisnik]

LGTM