REQ-FUN-103

Critical-path computation triggered on schedule change

ID: REQ-FUN-103
Category: Functional Requirements
Status: approved
Priority: P0
Created: 2026-05-11T18:34:00.000Z
Approved: 2026-05-11T18:37:00.000Z
Updated: 2026-05-11T18:37:00.000Z

What

System SHALL compute the critical path of a project schedule automatically when any activity or dependency is created, updated, or deleted, and SHALL expose the result via GET /v1/projects/{id}/schedule/critical-path and the equivalent MCP tool.

Why

established project management guidelines Develop Schedule + Control Schedule both depend on a known critical path to identify schedule-driving activities and slack.

How

Standard forward-pass + backward-pass CPM over the activity-dependency DAG; outputs ES/EF/LS/LF/total-float per activity and the ordered list of critical-path activity IDs; results memoized per (project_id, schedule_version) tuple; recomputation cost capped by REQ-NFR-067.

Done when

Critical-path response includes the activity ID list, per-activity float, and project duration; round-trip test on a 50-activity network gives results matching a reference Python CPM implementation.

Out of scope

Resource-constrained critical path (RCPM); probabilistic CPM.

established project management guidelines Mapping

Primary Knowledge Area: Schedule Management
Secondary KAs: none
Primary Process Group: Planning
established project management guidelines Deliverable: Schedule Baseline, Status Report

Critical path is the central output of established project management guidelines Develop Schedule.