calibration: count same-day closes honestly (#34)

The cold-start surface showed "N/20 closed issues estimated", implying you're
just (20−N) closes away. But calibrationSamples silently drops closed+estimated
issues that closed in 0 working days (same-day closes) — real closes that
structurally can't calibrate. On this repo that's 10 of 24 closes hidden: the
note read 14/20 as if 6 away, when a third of the history will never count.

- core: `calibrationCoverage(issues, timelines, asOf)` → { candidates, usable,
  excludedSameDay }, counting the silently-excluded same-day closes. Pure, tested.
- surface it: CalibrationData gains `excludedSameDay`; backlogCalibration returns
  the coverage; the Runway note and the Calibration screen now say "… · N same-day
  closes can't calibrate" so the thin sample is explained, not just reported.

Verified on christian/commitea: closed=24, usable=14, excludedSameDay=10.
131 core green (incl. new coverage test); core + desktop typecheck; 14 fixture e2e.

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

apps/desktop/src/renderer/src/components/screens/calibration-screen.tsx

@@ -178,6 +178,9 @@ export function CalibrationScreen({ onBack, data }: { onBack: () => void; data?:
               {c.active
                 ? 'You are not bad at estimating; you are optimistic in a very stable way. Stable, I can work with.'
                 : 'Not enough closed history yet — I’m forecasting from cold-start priors and widening the cone to stay honest. The curve takes over at 20.'}
+              {!c.active && c.excludedSameDay > 0
+                ? ` And ${c.excludedSameDay} closed ${c.excludedSameDay === 1 ? 'issue' : 'issues'} closed the same day they were started — 0 working days can’t calibrate, so they don’t count toward the 20.`
+                : ''}
             </p>
           </Card>
         </div>

apps/desktop/src/renderer/src/components/screens/runway-screen.tsx

@@ -17,7 +17,7 @@ export function RunwayScreen({
 }: {
   onOpenCalibration: () => void
   onOpenMilestone: (id?: number) => void
-  calibration?: { n: number; coldStart: boolean }
+  calibration?: { n: number; coldStart: boolean; excludedSameDay?: number }
   milestones?: RunwayMilestone[]
   capacity?: CapacityMember[]
 }) {
@@ -30,9 +30,11 @@ export function RunwayScreen({
           hours: `${capacityPerWorkday(m).toFixed(2)} pd/day`,
         }))
       : CAPACITY
+  const excluded = calibration?.excludedSameDay ?? 0
   const calibNote = calibration
     ? calibration.coldStart
-      ? `cold-start priors · ${calibration.n}/20 closed issues estimated`
+      ? `cold-start priors · ${calibration.n}/20 closed issues estimated` +
+        (excluded > 0 ? ` · ${excluded} same-day close${excluded === 1 ? '' : 's'} can’t calibrate` : '')
       : `calibrated on ${calibration.n} closed ${calibration.n === 1 ? 'issue' : 'issues'}`
     : 'calibrated on 27 closed issues'
   return (

apps/desktop/src/renderer/src/components/shell/app-shell.tsx

@@ -241,7 +241,15 @@ export function AppShell() {
               setMilestoneId(id ?? null)
               setView('milestone')
             }}
-            calibration={calibration ? { n: calibration.model.n, coldStart: calibration.model.coldStart } : undefined}
+            calibration={
+              calibration
+                ? {
+                    n: calibration.model.n,
+                    coldStart: calibration.model.coldStart,
+                    excludedSameDay: calibration.coverage.excludedSameDay,
+                  }
+                : undefined
+            }
             milestones={runwayMilestones}
             capacity={capacityMembers}
           />

apps/desktop/src/renderer/src/data/fixtures.ts

@@ -361,11 +361,14 @@ export interface CalibrationData {
   scatter: number[][]
   fit: number
   effect: { raw: string; banded: string; p50: string }
+  /** Closed+estimated issues that can't calibrate (same-day / 0-day closes). */
+  excludedSameDay: number
 }
 
 export const CALIBRATION: CalibrationData = {
   n: 27,
   active: true,
+  excludedSameDay: 0,
   labels: [
     { label: 'est/1d', n: 8, median: '1.1d', bias: 8 },
     { label: 'est/2d', n: 9, median: '2.4d', bias: 18 },

apps/desktop/src/renderer/src/lib/backlog.ts

@@ -1,6 +1,8 @@
 import {
+  type CalibrationCoverage,
   type CalibrationModel,
   type CalibrationSample,
+  calibrationCoverage,
   calibrationSamples,
   type CapacityMember,
   capacityPerWorkday,
@@ -171,10 +173,11 @@ export function backlogCalibration(
   issues: GiteaIssue[],
   timelines: Timelines = {},
   asOf: Date = new Date(),
-): { model: CalibrationModel; data: CalibrationData } {
+): { model: CalibrationModel; data: CalibrationData; coverage: CalibrationCoverage } {
   const samples = calibrationSamples(issues, timelines, asOf)
   const model = fitCalibration(samples)
-  return { model, data: calibrationData(model, samples, issues) }
+  const coverage = calibrationCoverage(issues, timelines, asOf)
+  return { model, coverage, data: calibrationData(model, samples, issues, coverage.excludedSameDay) }
 }
 
 const pctFromMu = (mu: number) => Math.round((Math.exp(mu) - 1) * 100)
@@ -188,6 +191,7 @@ export function calibrationData(
   model: CalibrationModel,
   samples: CalibrationSample[],
   openIssues: GiteaIssue[],
+  excludedSameDay = 0,
 ): CalibrationData {
   const labels = PRIOR_BUCKETS.map((b) => {
     const inBucket = samples.filter((s) => s.bucket === b)
@@ -227,6 +231,7 @@ export function calibrationData(
     scatter: samples.map((s) => [s.estimateDays, s.actualWorkingDays]),
     fit: Number(Math.exp(model.global.mu).toFixed(2)),
     effect,
+    excludedSameDay,
   }
 }