Timeline surface over knowledge-work entities — roadmap as a rendered view of PROJECT / MILESTONE / WORK_ITEM

[wow-miley]

Context

socket-link/ampere#663 rejected ROADMAP as a canon type with the rationale that a roadmap is a view, not a noun — a rendering of PROJECT, MILESTONE, and WORK_ITEM over time. This ticket is that view: a Phosphor surface that renders the admitted knowledge-work entities as a timeline. Filed early by request.

Gate: opens after socket-link/ampere#663 merges and a producing Link exists so the surface renders real entities, not fixtures.

Objective

A timeline surface: projects as lanes, milestones as markers on targetDate, work items groupable into their projectId lane, statuses color-mapped from the closed CanonWorkStatus enum.

Expected Outcomes

• Timeline surface consuming the three entity types via their display models (never canon types directly — same isolation wall as all UI)
• Status → color mapping over the closed enum, exhaustively; providerStatus on detail inspection only
• Degrades gracefully: entities with no targetDate collect in an undated shelf rather than vanishing; empty projects render as empty lanes
• Consistent with existing Phosphor rendering conventions and thermal discipline (Breaker-aware if animated)

Tasks

1. Recon (STOP): verify merged entity shapes; survey existing Phosphor surface patterns and the VoxelFrame DTO path for whether the timeline is a Phosphor-rendered surface or a Compose surface consuming Phosphor conventions — record the verdict
2. Design pass: lane/marker/shelf layout against the design system
3. Implement against fixture data mirroring real merged shapes; swap to live entities when a producing Link ships
4. Validate: snapshot per CanonWorkStatus member; undated-shelf and empty-lane states covered

Technical Constraints

Read-only view; no scheduling/editing affordances; closed-enum styling only; performance within existing thermal budgets.

Out of Scope

Any ROADMAP canon type (rejected, recorded on socket-link/ampere#663); editing or re-planning interactions; Gantt-style dependency arrows (needs relation data the canon types don't carry — future widening question, not a rendering hack).

Agent: Opus for recon/design; Sonnet for implementation