feat: lifecycle inference from the issue timeline (#5)

Fill the board's Steeping / In-review columns (and the calibration actuals)
from real gitea timeline events, replacing the three-column-only v0.

core (@commitea/core):
- inferLifecycle(issue, events, asOf): five-column inference — closed → done;
  open PR ref → review; commit ref → steeping; any triage signal → triage;
  else diagnosis. Earliest event of each kind fixes the stage timestamp.
- Derives actualWorkingDays (work-start → close) — the estimate-vs-actual the
  calibration fit (D3) learns from — and steepingDays (first commit → now) for
  the board age badge.
- workingDaysBetween(): whole Mon–Fri days in [start, end), day-granular.
- normalizeTimeline() + client.getIssueTimeline(): map gitea's raw timeline
  (label/milestone → triage, commit_ref → commit, pull_ref → pull, close,
  reopen), drop the rest. Paginated.

app:
- reconcile now fetches every issue's timeline and returns it keyed by number;
  threaded through the bridge → useBacklog → board/focus.
- issuesToBoardColumns + scheduleFocus run inferLifecycle: real Steeping/In-review
  columns, steeping-age `days` badge, focus-card steeping badge.

Known refinement: gitea's pull_ref fires on any PR mention, so an issue merely
referenced in a PR body can read as In-review; distinguishing closing refs from
mentions needs the PR link's state (later). Re-opening multi-segment actuals
also deferred.

Verified: 63 core tests green (15 lifecycle, incl. workingDaysBetween + the five
transitions), desktop typecheck clean, 14 fixture e2e green, live spec asserts
the board's Done column is populated from real events.

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

packages/core/src/lifecycle/lifecycle-v0.ts

@@ -1,12 +1,10 @@
 /**
- * Lifecycle inference, v0 — the coarse column an issue sits in, derived from
- * *only* what a single issues-list read gives us (state, labels, milestone).
+ * Lifecycle inference.
  *
- * The real five-column inference (P1-5) needs the issue timeline: first
- * branch/commit ref → Steeping, PR opened → In review, PR merged → Deploy.
- * Until that lands, v0 can only place three columns honestly; `steeping` and
- * `review` stay empty rather than guess. Board renders all five columns and
- * fills the middle two once the event stream is available.
+ * `inferColumnV0` places the coarse three columns from a single issues-list
+ * read (state/labels/milestone). `inferLifecycle` (#5) adds the issue timeline:
+ * first commit ref → Steeping, first PR ref → In review, close → Done — and
+ * derives the estimate-vs-actual working time that feeds calibration (D3).
  */
 
 import type { GiteaIssue } from '../gitea/types.js'
@@ -23,10 +21,109 @@ export const LIFECYCLE_COLUMNS: readonly LifecycleColumn[] = [
 
 /**
  * Closed → done. Open with any human intent applied (a label or a milestone)
- * → triage. Open and bare → diagnosis. Never returns steeping/review in v0.
+ * → triage. Open and bare → diagnosis. Never returns steeping/review — that's
+ * `inferLifecycle`, which reads the event stream.
  */
 export function inferColumnV0(issue: Pick<GiteaIssue, 'state' | 'labels' | 'milestone'>): LifecycleColumn {
   if (issue.state === 'closed') return 'done'
   const hasIntent = issue.labels.length > 0 || issue.milestone !== null
   return hasIntent ? 'triage' : 'diagnosis'
 }
+
+/** A timeline signal, normalized from gitea's raw event stream. */
+export type LifecycleEventType = 'triage' | 'commit' | 'pull' | 'close' | 'reopen'
+
+export interface LifecycleEvent {
+  type: LifecycleEventType
+  /** ISO timestamp. */
+  at: string
+}
+
+/** Timestamps for the stages an issue has reached (absent = not yet reached). */
+export interface LifecycleStages {
+  opened: string
+  /** First label / milestone / assignment. */
+  triaged?: string
+  /** First commit referencing the issue — work began. */
+  steeping?: string
+  /** First PR referencing the issue — in review. */
+  review?: string
+  /** Closed. */
+  done?: string
+}
+
+export interface LifecycleInference {
+  column: LifecycleColumn
+  stages: LifecycleStages
+  /**
+   * Working days from work-start (steeping → triaged → opened, first available)
+   * to done. Only for closed issues — this is the "actual" calibration learns
+   * from. null while open.
+   */
+  actualWorkingDays: number | null
+  /** Working days the issue has been steeping (first commit → asOf); null unless currently steeping. */
+  steepingDays: number | null
+}
+
+const DAY_MS = 86_400_000
+
+/**
+ * Whole working days (Mon–Fri) in the half-open interval [start, end). Same day
+ * or reversed → 0. Day-granular by design — estimates are in days.
+ */
+export function workingDaysBetween(start: Date, end: Date): number {
+  const s = Date.UTC(start.getUTCFullYear(), start.getUTCMonth(), start.getUTCDate())
+  const e = Date.UTC(end.getUTCFullYear(), end.getUTCMonth(), end.getUTCDate())
+  if (e <= s) return 0
+  let count = 0
+  for (let t = s; t < e; t += DAY_MS) {
+    const dow = new Date(t).getUTCDay()
+    if (dow !== 0 && dow !== 6) count += 1
+  }
+  return count
+}
+
+/**
+ * The five-column inference. Column reflects the furthest stage still in play:
+ * closed → done; else an open PR ref → review; else a commit ref → steeping;
+ * else any triage signal (or a current label/milestone) → triage; else
+ * diagnosis. Stage timestamps are the earliest event of each kind.
+ */
+export function inferLifecycle(
+  issue: Pick<GiteaIssue, 'state' | 'labels' | 'milestone' | 'createdAt' | 'closedAt'>,
+  events: LifecycleEvent[],
+  asOf: Date,
+): LifecycleInference {
+  const sorted = [...events].sort((a, b) => a.at.localeCompare(b.at))
+  const firstOf = (type: LifecycleEventType) => sorted.find((e) => e.type === type)?.at
+
+  const stages: LifecycleStages = { opened: issue.createdAt }
+  const triagedAt = firstOf('triage')
+  const steepingAt = firstOf('commit')
+  const reviewAt = firstOf('pull')
+  if (triagedAt) stages.triaged = triagedAt
+  if (steepingAt) stages.steeping = steepingAt
+  if (reviewAt) stages.review = reviewAt
+  const doneAt = issue.state === 'closed' ? (issue.closedAt ?? firstOf('close')) : undefined
+  if (doneAt) stages.done = doneAt
+
+  let column: LifecycleColumn
+  if (issue.state === 'closed') column = 'done'
+  else if (reviewAt) column = 'review'
+  else if (steepingAt) column = 'steeping'
+  else if (triagedAt || issue.labels.length > 0 || issue.milestone !== null) column = 'triage'
+  else column = 'diagnosis'
+
+  let actualWorkingDays: number | null = null
+  if (stages.done) {
+    const start = stages.steeping ?? stages.triaged ?? stages.opened
+    actualWorkingDays = workingDaysBetween(new Date(start), new Date(stages.done))
+  }
+
+  let steepingDays: number | null = null
+  if (column === 'steeping' && stages.steeping) {
+    steepingDays = workingDaysBetween(new Date(stages.steeping), asOf)
+  }
+
+  return { column, stages, actualWorkingDays, steepingDays }
+}