feat(api): POST /api/turn ticks the queue one turn; an empty queue is a free skip (#44)

app/api/turn/route.test.ts

@@ -0,0 +1,70 @@
+// Handler-level tests for the manual tick route (Task 5b): POST /api/turn (no body) advances
+// exactly one turn — an empty queue is a FREE SKIP (200, turn +1, nothing else changes, the
+// route never rejects), and a mid-countdown ACTIVE task decrements by exactly one in both the
+// returned snapshot and the persisted row (no resolution, no mission hook — it never hits 0).
+import { mkdtemp, rm } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import path from 'node:path'
+import { afterAll, describe, expect, it } from 'vitest'
+import { getGameDb, type GameDb } from '@/lib/db/client'
+import * as schema from '@/lib/db/schema'
+import { addCrew, buildWorldFixture, insertTaskRow } from '@/lib/game/test-fixtures'
+import { POST } from './route'
+
+const dirs: string[] = []
+// The route talks to the app-process singleton (getGameDb), so each test points it at a
+// fresh temp file and uses that very instance for fixtures and assertions — two in-memory
+// sql.js copies of one file would never see each other's writes.
+const g = globalThis as unknown as { __spaceWandererGameDb?: Promise<GameDb> }
+
+async function freshFile(): Promise<{ db: GameDb; file: string }> {
+  const dir = await mkdtemp(path.join(tmpdir(), 'sw-turn-route-test-'))
+  dirs.push(dir)
+  const file = path.join(dir, 'test.db')
+  process.env.SPACE_WANDERER_DB_PATH = file
+  delete g.__spaceWandererGameDb
+  return { db: await getGameDb(), file }
+}
+
+afterAll(async () => {
+  delete process.env.SPACE_WANDERER_DB_PATH
+  delete g.__spaceWandererGameDb
+  for (const d of dirs) await rm(d, { recursive: true, force: true })
+})
+
+// No request body — the handler never reads one.
+const post = () => POST()
+
+describe('POST /api/turn', () => {
+  it('empty queue → free skip: 200, turn +1, nothing else changes', async () => {
+    const { db } = await freshFile()
+    await buildWorldFixture(db)
+    const [before] = await db.db.select().from(schema.saves)
+
+    const res = await post()
+    expect(res.status).toBe(200)
+    const snap = await res.json()
+    expect(snap.turn).toBe(before.turn + 1)
+    expect(await db.db.select().from(schema.tasks)).toHaveLength(0) // the tick creates nothing
+    expect(snap.tasks).toEqual([]) // the composed queue array is empty
+  })
+
+  it('one ACTIVE task → 200, remaining decrements by exactly 1 in the returned snapshot', async () => {
+    const { db } = await freshFile()
+    const f = await buildWorldFixture(db)
+    const [c1] = await addCrew(db, 1)
+    const [before] = await db.db.select().from(schema.saves)
+    // Fixture task: one ACTIVE row, mid-countdown — a direct insert on the queue table
+    // (the 4b save.test pattern: it works with the queue rows directly); it never reaches 0
+    // this tick, so no resolver and no mission hook runs
+    await insertTaskRow(db, { type: 'JUMP', payload: { systemId: f.sys1, hops: 1 }, leadCrewId: c1, helpers: [], duration: 5, remaining: 3, status: 'ACTIVE', queuedAtTurn: before.turn })
+
+    const res = await post()
+    expect(res.status).toBe(200)
+    const snap = await res.json()
+    expect(snap.turn).toBe(before.turn + 1)
+    expect(snap.tasks).toHaveLength(1)
+    expect(snap.tasks[0].remaining).toBe(2) // 3 − 1: exactly one decrement
+    expect((await db.db.select().from(schema.tasks))[0].remaining).toBe(2) // the persisted row matches the snapshot
+  })
+})

app/api/turn/route.ts

@@ -0,0 +1,21 @@
+import { getGameDb } from '@/lib/db/client'
+import { getWorldState, runTurn } from '@/lib/game/save'
+
+// The manual tick (spec §3): advance exactly one turn — every ACTIVE task ages by one, tasks
+// that reach 0 resolve (the 4a resolvers + their mission hooks, 4b), and PENDING successors
+// auto-start in FIFO order. An empty queue is a FREE SKIP: turn +1 with nothing else changed —
+// the route never rejects a tick, so the UI's NEXT TURN button is never disabled. No request
+// body. Returns the same world snapshot GET /api/world returns, composed with the tick's
+// task array (the snapshot readers do not select the tasks table, so it comes from the TickResult).
+export async function POST() {
+  try {
+    const db = await getGameDb()
+    const tick = await runTurn(db)
+    return Response.json({ ...(await getWorldState(db)), tasks: tick.tasks })
+  } catch (err) {
+    // No domain errors escape runTurn (4b fails the task instead) — anything reaching here is
+    // a non-domain rethrow, i.e. a real bug: the error-mapping pattern, 500 when no status.
+    const e = err as { status?: number; message: string }
+    return Response.json({ error: e.message }, { status: e.status ?? 500 })
+  }
+}