feat: capacity-aware scheduling (#8) — real focus factors drive every forecast

Turns the single-serial-worker scheduler into a capacity-aware, multi-lane one.
Configured team members become lanes; an issue runs on its assignee's lane (or the
earliest-free lane), its duration scaled by that lane's throughput
(focusFactor × allocation). Every forecast — Focus cone, Runway, milestone
drill-in — is now capacity-aware.

core (@commitea/core):
- capacity/capacity-v0: CapacityMember + capacityPerWorkday + parseCapacityConfig
  (clamps, drops invalid; degrades to []).
- scheduler/scheduler-capacity-v0: scheduleWithCapacity reuses the v0 topo order +
  critical path, re-lays work across lanes (layoutOnLanes, resolveLanes, makespan).
  Empty workers → the single serial plan verbatim.
- forecast() gains options.workers: each MC trial lays sampled durations across the
  lanes and takes the makespan; serial path unchanged. SchedulableIssue gains
  assignee; ScheduledItem gains worker.
- 11 new tests (parse/clamp, parallelism halves makespan, speed scaling, assignee
  routing, cross-lane deps, forecast makespan shrinks with lanes).

app:
- pm-state capacity/members.json read (readCapacity + pmstate:capacity bridge);
  useCapacity hook → workers; forecastBacklog/runwayView/milestoneView pass workers.
- Runway Capacity card shows the real config (person · focus · alloc · pd/day).

Config lives in pm-state (D4); seeded christian(0.8)/stephen(0.6×0.5). Degrades to
the fixture/serial when absent.

Verified: 128 core tests green, desktop typecheck clean, 14 fixture e2e green. Live:
the capacity card is real, and the P2 forecast shifts 32d→37d — honest, since real
focus factors (<1) replace the v0 focus-1.0 assumption.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/core/src/capacity/capacity-v0.test.ts

@@ -0,0 +1,88 @@
+import { describe, expect, it } from 'vitest'
+
+import { type DependencyEdge, type SchedulableIssue } from '../scheduler/scheduler-v0.js'
+import { makespan, scheduleWithCapacity, type Worker } from '../scheduler/scheduler-capacity-v0.js'
+import { capacityPerWorkday, parseCapacityConfig } from './capacity-v0.js'
+
+describe('capacity model', () => {
+  it('capacityPerWorkday = focusFactor × allocation', () => {
+    expect(capacityPerWorkday({ person: 'a', focusFactor: 0.8, allocation: 0.5 })).toBeCloseTo(0.4)
+  })
+
+  it('parses + clamps config, drops invalid members', () => {
+    const members = parseCapacityConfig({
+      members: [
+        { person: 'christian', focusFactor: 0.8, allocation: 1 },
+        { person: 'ak', focusFactor: 1.5, allocation: -1 }, // clamps to 1 / 0 → zero capacity → dropped
+        { focusFactor: 0.8 }, // no person → dropped
+      ],
+    })
+    expect(members).toEqual([{ person: 'christian', focusFactor: 0.8, allocation: 1 }])
+  })
+
+  it('returns [] for a non-array/absent members field', () => {
+    expect(parseCapacityConfig({})).toEqual([])
+    expect(parseCapacityConfig({ members: 'nope' })).toEqual([])
+  })
+})
+
+function issue(number: number, over: Partial<SchedulableIssue> = {}): SchedulableIssue {
+  return { number, title: `#${number}`, labels: [], estimateDays: 4, priority: 2, ...over }
+}
+
+describe('scheduleWithCapacity', () => {
+  it('with no workers, falls back to the single serial plan', () => {
+    const issues = [issue(1), issue(2)]
+    const plan = scheduleWithCapacity(issues, [], [])
+    expect(makespan(plan)).toBe(8) // 4 + 4 serial
+  })
+
+  it('parallelizes independent work across lanes (makespan shrinks)', () => {
+    const issues = [issue(1), issue(2), issue(3), issue(4)] // 4×4d = 16d serial
+    const one: Worker[] = [{ person: 'a', speed: 1 }]
+    const two: Worker[] = [
+      { person: 'a', speed: 1 },
+      { person: 'b', speed: 1 },
+    ]
+    expect(makespan(scheduleWithCapacity(issues, [], one))).toBe(16)
+    expect(makespan(scheduleWithCapacity(issues, [], two))).toBe(8) // two lanes → half
+  })
+
+  it('scales duration by a lane speed (slower lane takes longer)', () => {
+    const plan = scheduleWithCapacity([issue(1, { estimateDays: 4 })], [], [{ person: 'a', speed: 0.5 }])
+    expect(plan.items[0].durationDays).toBe(8) // 4 / 0.5
+    expect(plan.items[0].worker).toBe('a')
+  })
+
+  it('routes an issue to its assignee lane', () => {
+    const issues = [issue(1, { assignee: 'ak' }), issue(2, { assignee: 'sm' })]
+    const workers: Worker[] = [
+      { person: 'ak', speed: 1 },
+      { person: 'sm', speed: 1 },
+    ]
+    const plan = scheduleWithCapacity(issues, [], workers)
+    const byN = Object.fromEntries(plan.items.map((i) => [i.number, i]))
+    expect(byN[1].worker).toBe('ak')
+    expect(byN[2].worker).toBe('sm')
+    // both start at 0 (different lanes) → parallel
+    expect(byN[1].startDay).toBe(0)
+    expect(byN[2].startDay).toBe(0)
+  })
+
+  it('adds a lane for an assignee not in the config (mean speed)', () => {
+    const plan = scheduleWithCapacity([issue(1, { assignee: 'newbie' })], [], [{ person: 'a', speed: 0.5 }])
+    expect(plan.items[0].worker).toBe('newbie')
+    expect(plan.items[0].durationDays).toBe(8) // mean speed 0.5 → 4/0.5
+  })
+
+  it('respects dependencies across lanes (a blocker finishes before its dependent starts)', () => {
+    const edges: DependencyEdge[] = [{ issue: 2, dependsOn: 1 }]
+    const workers: Worker[] = [
+      { person: 'a', speed: 1 },
+      { person: 'b', speed: 1 },
+    ]
+    const plan = scheduleWithCapacity([issue(1), issue(2)], edges, workers)
+    const byN = Object.fromEntries(plan.items.map((i) => [i.number, i]))
+    expect(byN[2].startDay).toBeGreaterThanOrEqual(byN[1].endDay) // #2 waits for #1 even on another lane
+  })
+})