Modern software engineers operate across 5-10 disconnected tools daily: GitHub, GitLab, Jira, Slack, calendar applications, CI dashboards, AI coding assistants, and container platforms. This fragmentation creates cognitive overhead that interrupts deep work and delays response to critical engineering signals. We present Workstream, an open-source, local-first developer command center that aggregates pull requests, task management, calendar, AI-powered code review, historical review intelligence, repository AI-readiness scoring, and agent observability into a single interface. We describe the system architecture, a novel 5-category AI readiness scoring algorithm, a review intelligence pipeline that mines historical PR reviews for team-specific patterns, and an agent observability layer implementing the Model Context Protocol (MCP), Agent-to-Agent (A2A), and Agent Observability Protocol (AOP). Through a case study of applying the tool to its own development, we demonstrate measurable improvements in AI-readiness scores (48 to 98 on our internal scanner; 41.6 to 73.7 on the independent agentready CLI). Workstream is released as open source under the Apache 2.0 license at https://github.com/happybhati/workstream.