feat: replace current_milestone with active_gsd_milestone in project.json

[snipcodeit]

Summary

Replace the current_milestone integer pointer with active_gsd_milestone string (GSD milestone ID). Add resolveActiveMilestoneIndex() in state.cjs for backward-compatible resolution. Update all consumers: milestone.md, next.md, status.md, run.md.

Backward Compatibility

• If current_milestone exists and active_gsd_milestone does not: use current_milestone - 1 as 0-based index (legacy)
• If active_gsd_milestone exists: find matching gsd_milestone_id in milestones array
• If neither: return -1 (error state)

Files

• lib/state.cjs — add resolveActiveMilestoneIndex(), update module.exports
• commands/milestone.md — replace current_milestone reads/writes with resolveActiveMilestoneIndex + active_gsd_milestone
• commands/next.md — update milestone resolution
• commands/status.md — update milestone resolution, add GSD milestone display
• commands/run.md — update milestone context lookup

GSD Route

gsd:plan-phase

Depends On

• A4 (gsd_milestone_id field must exist on milestones)

[snipcodeit]

MGW execution-complete · 2026-03-01T00:00:00Z
Milestone: v3 — Multi-Milestone Tracking | Phase 24: Active Milestone Schema

Implementation Complete

Implemented in commit 37f3d5f on branch feat/mgw-gsd-architecture-repair.

Updated all command consumers to use resolveActiveMilestoneIndex() from lib/state.cjs instead of reading current_milestone directly:

• commands/milestone.md: parse_arguments, resume_detection, execute_loop, post_loop steps
• commands/run.md: milestone context lookup in post_triage_update
• commands/next.md: load_state step
• commands/status.md: replaced current_milestone read, added active_milestone_idx and gsd_id fields

Part of PR #102.