feat: Baseline management — create, name, compare baselines with change control

Summary

Formal baseline management for project schedules: capture a named point-in-time snapshot of the approved schedule, compare any two baselines side by side, track variance trending over time, and enforce change control when re-baselining is requested. Required for regulated-industry and government work; referenced in the Gantt UI (baseline shadow bars) and EVM engine (BAC derivation).

Scope

Baseline creation

  • "Capture baseline" action on a project: saves a snapshot of all tasks, durations, dependencies, assignments, dates, and cost plan at that point in time
  • Name and description required (e.g. "v1 — Contract award", "v2 — Approved scope change #3 (closed)")
  • Maximum baselines per project: configurable (default 10)
  • Baseline is immutable after creation; no edits allowed without creating a new baseline

Baseline display on Gantt

  • Baseline shadow bars shown below current task bars (as referenced in existing Gantt spec)
  • Toggle which baseline to show as shadow (dropdown: Original / v2 / v3 / …)
  • Baseline drift label on each task: "Baseline drift: +4d vs v2" (as referenced in Attention widget)

Baseline comparison view

  • Select any two baselines to compare side by side (or baseline vs. current schedule)
  • Comparison table: for each task, show planned dates in each baseline and variance
  • Summary: total schedule slip, number of tasks shifted, critical path delta
  • Visual diff: Gantt with color-coded bars (on schedule / slipped / accelerated)

Variance trending

  • Chart: baseline drift over time — as of each status date, what was the cumulative slip vs. original baseline?
  • Milestones view: track each key milestone across baselines to show when slippage was introduced

Change control

  • Re-baseline request: PM submits a re-baseline request with justification
  • In the OSS edition: request is logged and the PM can approve their own request (simple unlock)
  • In the enterprise edition: re-baseline triggers a governance approval chain (enterprise #47 (closed))
  • Audit log: every baseline creation and approval recorded with who/when/why

API

  • GET /api/v1/projects/{id}/baselines/ — list baselines for a project
  • POST /api/v1/projects/{id}/baselines/ — capture a new baseline
  • GET /api/v1/projects/{id}/baselines/{baseline_id}/ — retrieve baseline snapshot
  • GET /api/v1/projects/{id}/baselines/compare/?a={id}&b={id} — comparison data

Acceptance criteria

  • Baseline captures exact snapshot of all task fields and dates at creation time
  • Baseline is immutable: no task field edit via API without re-baselining
  • Gantt renders shadow bars for selected baseline on all tasks
  • Comparison view shows correct variance for each task between two baselines
  • Variance trending chart plots correct cumulative slip at each status date
  • Audit log records all baseline creation events

Related

  • Enterprise #3 (closed) (EVM — BAC derived from baseline cost plan)
  • Enterprise #47 (closed) (governance workflows — re-baseline approval in enterprise edition)