Overview

Add explicit buffering control to the UserOutput module by providing a flush() method. While writes are typically line-buffered by default, explicit flush control ensures output appears immediately when needed and provides better testing capabilities.

Specification

See detailed specification: docs/issues/138-add-buffering-control.md

Goals

• Add flush() method to UserOutput for explicit buffer control
• Document buffering behavior in module documentation
• Add tests demonstrating flush behavior
• Maintain backward compatibility with existing API
• Follow Rust standard patterns from Write trait

Implementation Plan

Phase 1: Core Implementation (30 minutes)

• Add flush() method to UserOutput
• Implement flush for both stdout and stderr writers
• Add rustdoc documentation for the method

Phase 2: Documentation (20 minutes)

• Update module-level documentation with buffering behavior section
• Add usage examples showing when to use flush()

Phase 3: Testing (30 minutes)

• Add unit tests for successful flush
• Add tests for multiple flush calls
• Add tests for empty buffer flushing

Phase 4: Quality Assurance (20 minutes)

• Run ./scripts/pre-commit.sh and fix any issues
• Verify all linters pass

Total Estimated Time: 2 hours

Acceptance Criteria

Functional Requirements

• UserOutput::flush() method flushes both stdout and stderr
• Flush can be called multiple times safely
• Flush returns std::io::Result<()> for error handling
• Existing functionality is not affected

Testing Requirements

• Unit tests cover successful flush scenarios
• Tests verify idempotency (multiple flushes are safe)
• All existing tests continue to pass

Quality Requirements

• Pre-commit checks pass: ./scripts/pre-commit.sh
• Code follows project conventions

Related

• Parent Epic: [EPIC] User Output Architecture Improvements #102 - User Output Architecture Improvements
• Refactoring Plan: docs/refactors/plans/user-output-architecture-improvements.md
• Depends On: Type-Safe Channel Routing for User Output #135 - Type-Safe Channel Routing

Labels

enhancement, phase-2, user-output, P2

Priority

P2 (Phase 2 - Polish & Extensions)

Estimated Effort

2 hours