Merge pull request '[READY][Gameplay] #310 Host transition idempotency and error catalog for scoreboard -> next round / finish' (#320) from dev/issue-310-host-transition-idempotency-v2 into main

Reviewed-on: #320
Reviewed-by: reviewer-bot <review-no-reply@weircon.dk>

.gitea/workflows/ci.yml

@@ -38,7 +38,10 @@ jobs:
           node-version: "22"
 
       - name: Install SPA dependencies
-        run: npm ci --prefix frontend/angular
+        run: |
+          npm ci --prefix frontend/angular
+          node -e "require('./frontend/angular/node_modules/rollup/dist/native.js')" \
+            || npm install --prefix frontend/angular
 
       - name: SPA Angular smoke tests
         run: npm --prefix frontend/angular test

docs/ISSUE-301-CLIENT-ACTION-GATING-ARTIFACT.md

@@ -0,0 +1,52 @@
+# Issue #301 Artifact — Client action gating from canonical phase state
+
+Refs: #287, #301
+
+## What changed
+
+Frontend host/player shells now prefer the canonical phase exposed by `phase_view_model.current_phase` when deciding:
+
+- which gameplay actions are enabled
+- whether reveal data should still be shown
+- which SPA hash-route should represent the active game state
+
+This tightens the #301 slice so the client stays aligned with backend canonicalisation even when `session.status` lags during reveal/scoreboard promotion.
+
+## Gated UI actions by phase
+
+### Lobby
+- **Host:** `startRound`
+- **Player:** `join`
+
+### Bluff / lie
+- **Host:** `showQuestion`
+- **Player:** `submitLie`
+- **Blocked:** guess submission, scoreboard load, next round, finish game
+
+### Guess
+- **Host:** `mixAnswers`, `calculateScores`
+- **Player:** `submitGuess`
+- **Blocked:** lie submission, scoreboard load, next round, finish game
+
+### Reveal
+- **Host:** `loadScoreboard`
+- **Player:** display-only reveal state
+- **Blocked:** start next round, finish game, guess/lie submission
+
+### Scoreboard
+- **Host:** `startNextRound`, `finishGame`
+- **Player:** display-only reveal/scoreboard state
+- **Blocked:** scoreboard reload, guess/lie submission
+
+## Test evidence
+
+Targeted tests added/updated for:
+
+- host shell canonical gating and route sync when `current_phase` differs from `session.status`
+- player shell canonical gating and route sync when `current_phase` differs from `session.status`
+- shared gameplay phase machine gating from canonical permissions
+- shared API mapper contract coverage, including reveal/scoreboard payload stability
+
+## Contract note
+
+No backend protocol redesign was introduced. This follow-up only preserves and consumes the existing canonical phase/action contract more strictly on the client side.

docs/ISSUE-302-CANONICAL-LOOP-EVIDENCE.md

@@ -0,0 +1,55 @@
+# Issue #302 Evidence — canonical bluff → guess → reveal → scoreboard regression
+
+## Runnable command
+
+```bash
+python manage.py migrate --noinput
+python manage.py smoke_staging --artifact docs/artifacts/issue-302-canonical-loop-smoke.json
+```
+
+`migrate` is the normal local bootstrap precondition when the database has not been initialized yet; the regression evidence itself is produced by `smoke_staging`.
+
+## What the regression proves
+
+`smoke_staging` now exercises one full canonical round and fails fast with step-specific diagnostics if any of these break:
+
+1. `start_round` lands the session in `lie` and returns a concrete `round_question_id`.
+2. Final `submit_lie` auto-advances the session to `guess` and exposes mixed answers containing both the correct answer and player bluffs.
+3. Final `submit_guess` auto-advances the session to `reveal` and returns the canonical reveal payload.
+4. The reveal payload includes:
+   - correct answer
+   - all lies
+   - all guesses
+   - fooled-player references for bluff hits
+5. The first canonical state read after reveal promotes the session to `scoreboard`.
+6. Scoreboard promotion preserves the same reveal payload and exposes a leaderboard with `scoreboard_ready=true`.
+
+## Artifact shape
+
+When `--artifact` is provided, the JSON file records:
+
+- the exact smoke command
+- session code and round question id
+- deterministic guess plan used to produce both bluff hits and one correct guess
+- per-step evidence for:
+  - `create_session`
+  - `join_players`
+  - `start_round`
+  - `auto_guess_transition`
+  - `submit_guesses`
+  - `auto_reveal_transition`
+  - `auto_scoreboard_transition`
+  - `finish_game`
+- reveal summary (`correct_answer`, lie/guess counts, fooled-player ids, correct guess player ids)
+- promoted scoreboard leaderboard payload
+
+## Targeted test coverage
+
+Backend regression coverage lives in `lobby/tests.py`:
+
+- `test_smoke_staging_command_runs_full_flow`
+- `test_smoke_staging_writes_phase_evidence_artifact_when_requested`
+
+Together they ensure the command stays runnable in normal workflow and that the evidence artifact contains phase-by-phase proof instead of only a generic pass/fail.
+
+Refs #287 #302

docs/artifacts/issue-302-canonical-loop-smoke.json

@@ -0,0 +1,110 @@
+{
+  "ok": true,
+  "command": "python manage.py smoke_staging --artifact <path>",
+  "generated_at": "2026-03-16T15:19:30.105231+00:00",
+  "question": {
+    "prompt": "Smoke prompt?",
+    "correct_answer": "Correct"
+  },
+  "steps": [
+    {
+      "step": "create_session",
+      "session_status": "lobby"
+    },
+    {
+      "step": "join_players",
+      "players_count": 3
+    },
+    {
+      "step": "start_round",
+      "session_status": "lie",
+      "round_question_id": 1
+    },
+    {
+      "step": "auto_guess_transition",
+      "session_status": "guess",
+      "answers": [
+        "Lie from P3",
+        "Lie from P1",
+        "Lie from P2",
+        "Correct"
+      ]
+    },
+    {
+      "step": "submit_guesses",
+      "guess_results": [
+        {
+          "player_id": 1,
+          "selected_text": "Lie from P2",
+          "is_correct": false,
+          "fooled_player_id": 2
+        },
+        {
+          "player_id": 2,
+          "selected_text": "Correct",
+          "is_correct": true,
+          "fooled_player_id": null
+        },
+        {
+          "player_id": 3,
+          "selected_text": "Lie from P1",
+          "is_correct": false,
+          "fooled_player_id": 1
+        }
+      ]
+    },
+    {
+      "step": "auto_reveal_transition",
+      "session_status": "reveal",
+      "reveal": {
+        "correct_answer": "Correct",
+        "lies_count": 3,
+        "guesses_count": 3,
+        "fooled_player_ids": [
+          1,
+          2
+        ],
+        "correct_guess_player_ids": [
+          2
+        ]
+      }
+    },
+    {
+      "step": "auto_scoreboard_transition",
+      "session_status": "scoreboard",
+      "leaderboard": [
+        {
+          "id": 2,
+          "nickname": "P2",
+          "score": 7
+        },
+        {
+          "id": 1,
+          "nickname": "P1",
+          "score": 2
+        },
+        {
+          "id": 3,
+          "nickname": "P3",
+          "score": 0
+        }
+      ]
+    },
+    {
+      "step": "finish_game",
+      "session_status": "finished"
+    }
+  ],
+  "session_code": "7YV59E",
+  "players": [
+    "P1",
+    "P2",
+    "P3"
+  ],
+  "round_question_id": 1,
+  "guess_plan": {
+    "P1": "Lie from P2",
+    "P2": "Correct",
+    "P3": "Lie from P1"
+  }
+}

frontend/angular/src/app/features/host/host-shell.component.spec.ts

@@ -21,6 +21,7 @@ function createFetchRouteMock(handler: FetchRouteHandler): FetchMock {
 function sessionDetailPayload(
   status: string,
   options?: {
+    currentPhase?: string;
     roundQuestionId?: number | null;
     reveal?: {
       correct_answer: string;
@@ -81,6 +82,7 @@ function sessionDetailPayload(
           },
     phase_view_model: {
       status,
+      current_phase: options?.currentPhase ?? status,
       round_number: 1,
       players_count: 2,
       constraints: {
@@ -89,14 +91,18 @@ function sessionDetailPayload(
         min_players_reached: true,
         max_players_allowed: true,
       },
+      readiness: {
+        question_ready: (options?.currentPhase ?? status) !== 'lobby',
+        scoreboard_ready: (options?.currentPhase ?? status) === 'reveal' || (options?.currentPhase ?? status) === 'scoreboard',
+      },
       host: {
-        can_start_round: status === 'lobby',
-        can_show_question: status === 'lie',
-        can_mix_answers: status === 'lie' || status === 'guess',
-        can_calculate_scores: status === 'guess',
-        can_reveal_scoreboard: status === 'reveal',
-        can_start_next_round: status === 'reveal',
-        can_finish_game: status === 'reveal',
+        can_start_round: (options?.currentPhase ?? status) === 'lobby',
+        can_show_question: (options?.currentPhase ?? status) === 'lie',
+        can_mix_answers: (options?.currentPhase ?? status) === 'lie' || (options?.currentPhase ?? status) === 'guess',
+        can_calculate_scores: (options?.currentPhase ?? status) === 'guess',
+        can_reveal_scoreboard: (options?.currentPhase ?? status) === 'reveal',
+        can_start_next_round: (options?.currentPhase ?? status) === 'scoreboard',
+        can_finish_game: (options?.currentPhase ?? status) === 'scoreboard',
       },
       player: {
         can_join: status === 'lobby',
@@ -259,7 +265,7 @@ describe('HostShellComponent gameplay wiring', () => {
     component.scoreboardPayload = '{"leaderboard":[]}';
     component.finalLeaderboardPayload = '{"leaderboard":[{"nickname":"Old","score":1}]}' ;
     component.finalLeaderboard = [{ id: 9, nickname: 'Old', score: 1 }];
-    component.session = sessionDetailPayload('reveal', { roundQuestionId: 77 }) as any;
+    component.session = sessionDetailPayload('scoreboard', { roundQuestionId: 77 }) as any;
 
     await component.startNextRound();
 
@@ -296,7 +302,7 @@ describe('HostShellComponent gameplay wiring', () => {
 
     const component = new HostShellComponent();
     component.sessionCode = 'ABCD12';
-    component.session = sessionDetailPayload('reveal', { roundQuestionId: 77 }) as any;
+    component.session = sessionDetailPayload('scoreboard', { roundQuestionId: 77 }) as any;
 
     await component.finishGame();
     expect(component.finishError).toContain('Finish game failed: Final leaderboard timeout');
@@ -320,7 +326,7 @@ describe('HostShellComponent gameplay wiring', () => {
 
     const component = new HostShellComponent();
     component.sessionCode = '   ';
-    component.session = sessionDetailPayload('reveal', { roundQuestionId: 77 }) as any;
+    component.session = sessionDetailPayload('scoreboard', { roundQuestionId: 77 }) as any;
 
     await component.startNextRound();
     await component.finishGame();
@@ -351,6 +357,10 @@ describe('HostShellComponent gameplay wiring', () => {
     for (const status of ['lie', 'guess', 'scoreboard'] as const) {
       component.session = sessionDetailPayload(status, { roundQuestionId: 77 }) as any;
       await component.loadScoreboard();
+    }
+
+    for (const status of ['lie', 'guess', 'reveal'] as const) {
+      component.session = sessionDetailPayload(status, { roundQuestionId: 77 }) as any;
       await component.startNextRound();
       await component.finishGame();
     }
@@ -361,16 +371,42 @@ describe('HostShellComponent gameplay wiring', () => {
     component.session = sessionDetailPayload('reveal', { roundQuestionId: 77 }) as any;
     expect(component.canCalculateScores).toBe(false);
     expect(component.canLoadScoreboard).toBe(true);
-    expect(component.canStartNextRound).toBe(true);
-    expect(component.canFinishGame).toBe(true);
+    expect(component.canStartNextRound).toBe(false);
+    expect(component.canFinishGame).toBe(false);
 
     component.session = sessionDetailPayload('scoreboard', { roundQuestionId: 77 }) as any;
     expect(component.canLoadScoreboard).toBe(false);
-    expect(component.canStartNextRound).toBe(false);
-    expect(component.canFinishGame).toBe(false);
+    expect(component.canStartNextRound).toBe(true);
+    expect(component.canFinishGame).toBe(true);
     expect(fetchMock).not.toHaveBeenCalled();
   });
 
+  it('prefers canonical current_phase for reveal panel and host routing when status lags behind', async () => {
+    const fetchMock: FetchMock = vi.fn().mockResolvedValue(
+      jsonResponse(200, sessionDetailPayload('reveal', { currentPhase: 'scoreboard', roundQuestionId: 77, reveal: { correct_answer: 'Mercury' } }))
+    );
+    vi.stubGlobal('fetch', fetchMock);
+
+    const replaceState = vi.fn();
+    vi.stubGlobal('window', {
+      location: { hash: '#/host/reveal/ABCD12' },
+      history: { state: null, replaceState },
+      sessionStorage: { getItem: vi.fn().mockReturnValue(null), setItem: vi.fn() },
+    });
+
+    const component = new HostShellComponent();
+    component.sessionCode = 'ABCD12';
+
+    await component.refreshSession();
+
+    expect(component.gameplayPhase).toBe('scoreboard');
+    expect(component.showRevealPanel).toBe(true);
+    expect(component.canLoadScoreboard).toBe(false);
+    expect(component.canStartNextRound).toBe(true);
+    expect(component.canFinishGame).toBe(true);
+    expect(replaceState).toHaveBeenCalledWith(null, '', '#/host/scoreboard/ABCD12');
+  });
+
   it('syncs host hash-route with latest phase after refresh without page reload', async () => {
     const fetchMock: FetchMock = vi.fn().mockResolvedValue(jsonResponse(200, sessionDetailPayload('guess', { roundQuestionId: 77 })));
     vi.stubGlobal('fetch', fetchMock);
@@ -408,12 +444,12 @@ describe('HostShellComponent gameplay wiring', () => {
 
     component.session = sessionDetailPayload('reveal') as any;
     expect(component.canLoadScoreboard).toBe(true);
-    expect(component.canStartNextRound).toBe(true);
-    expect(component.canFinishGame).toBe(true);
+    expect(component.canStartNextRound).toBe(false);
+    expect(component.canFinishGame).toBe(false);
 
     component.session = sessionDetailPayload('scoreboard') as any;
     expect(component.canLoadScoreboard).toBe(false);
-    expect(component.canStartNextRound).toBe(false);
-    expect(component.canFinishGame).toBe(false);
+    expect(component.canStartNextRound).toBe(true);
+    expect(component.canFinishGame).toBe(true);
   });
 });

frontend/angular/src/app/features/host/host-shell.component.ts

@@ -48,7 +48,7 @@ type LeaderboardResponse = FinishGameResponse;
       <ul>
         <li *ngFor="let p of session.players">{{ p.nickname }}: {{ p.score }}</li>
       </ul>
-      <div class="panel" *ngIf="session.reveal && (session.session.status === 'reveal' || session.session.status === 'scoreboard')">
+      <div class="panel" *ngIf="showRevealPanel">
         <h3>Reveal</h3>
         <p><strong>Korrekt svar:</strong> {{ session.reveal.correct_answer }}</p>
         <p><strong>Spørgsmål:</strong> {{ session.reveal.prompt }}</p>
@@ -163,6 +163,10 @@ export class HostShellComponent implements OnInit, OnDestroy {
     return isHostGameplayActionAllowed(this.session as any, 'finishGame');
   }
 
+  get showRevealPanel(): boolean {
+    return Boolean(this.session?.reveal && (this.gameplayPhase === 'reveal' || this.gameplayPhase === 'scoreboard'));
+  }
+
   copy(key: string): string {
     return t(key, this.locale);
   }
@@ -364,7 +368,7 @@ export class HostShellComponent implements OnInit, OnDestroy {
       return;
     }
 
-    const phase = this.session.session.status || 'lobby';
+    const phase = this.gameplayPhase ?? this.session.session.status ?? 'lobby';
     const code = this.normalizeCode(this.session.session.code || this.sessionCode);
     if (!code) {
       return;

frontend/angular/src/app/features/player/player-shell.component.spec.ts

@@ -16,6 +16,7 @@ function jsonResponse(status: number, body: unknown) {
 function sessionDetailPayload(
   status: string,
   options?: {
+    currentPhase?: string;
     answers?: string[];
     players?: Array<{ id: number; nickname: string; score: number }>;
     roundQuestionId?: number | null;
@@ -79,6 +80,7 @@ function sessionDetailPayload(
           },
     phase_view_model: {
       status,
+      current_phase: options?.currentPhase ?? status,
       round_number: 1,
       players_count: (options?.players ?? []).length,
       constraints: {
@@ -87,6 +89,10 @@ function sessionDetailPayload(
         min_players_reached: true,
         max_players_allowed: true,
       },
+      readiness: {
+        question_ready: (options?.currentPhase ?? status) !== 'lobby',
+        scoreboard_ready: (options?.currentPhase ?? status) === 'reveal' || (options?.currentPhase ?? status) === 'scoreboard',
+      },
       host: {
         can_start_round: false,
         can_show_question: false,
@@ -97,10 +103,10 @@ function sessionDetailPayload(
         can_finish_game: false,
       },
       player: {
-        can_join: status === 'lobby',
-        can_submit_lie: status === 'lie',
-        can_submit_guess: status === 'guess',
-        can_view_final_result: status === 'finished',
+        can_join: (options?.currentPhase ?? status) === 'lobby',
+        can_submit_lie: (options?.currentPhase ?? status) === 'lie',
+        can_submit_guess: (options?.currentPhase ?? status) === 'guess',
+        can_view_final_result: (options?.currentPhase ?? status) === 'finished',
       },
     },
   };
@@ -437,6 +443,34 @@ describe('PlayerShellComponent gameplay wiring', () => {
     expect(values.get('wpp.session-context')).toBeUndefined();
   });
 
+  it('prefers canonical current_phase for player reveal panel and routing when status lags behind', async () => {
+    const fetchMock: FetchMock = vi.fn().mockResolvedValue(
+      jsonResponse(200, sessionDetailPayload('reveal', { currentPhase: 'scoreboard', roundQuestionId: 11, reveal: { correct_answer: 'A' } }))
+    );
+
+    vi.stubGlobal('fetch', fetchMock);
+
+    const replaceState = vi.fn();
+    const localStorage = { getItem: vi.fn().mockReturnValue(null), setItem: vi.fn(), removeItem: vi.fn() };
+    vi.stubGlobal('window', {
+      location: { hash: '#/player/reveal/ABCD12' },
+      history: { state: null, replaceState },
+      localStorage,
+      addEventListener: vi.fn(),
+      removeEventListener: vi.fn(),
+    });
+
+    const component = new PlayerShellComponent();
+    component.sessionCode = 'ABCD12';
+
+    await component.refreshSession();
+
+    expect(component.gameplayPhase).toBe('scoreboard');
+    expect(component.showRevealPanel).toBe(true);
+    expect(component.showGuessControls).toBe(false);
+    expect(replaceState).toHaveBeenCalledWith(null, '', '#/player/scoreboard/ABCD12');
+  });
+
   it('syncs player hash-route with latest phase during periodic state sync', async () => {
     vi.useFakeTimers();
 

frontend/angular/src/app/features/player/player-shell.component.ts

@@ -95,7 +95,7 @@ function resolveLocalStorage(): Storage | undefined {
         <button *ngIf="submitError?.kind === 'guess'" (click)="submitGuess()" [disabled]="loading || !canSubmitGuess">{{ copy('player.retry_guess_submit') }}</button>
       </ng-container>
 
-      <div class="panel" *ngIf="session.reveal && (session.session.status === 'reveal' || session.session.status === 'scoreboard')">
+      <div class="panel" *ngIf="showRevealPanel">
         <h3>Reveal</h3>
         <p><strong>Korrekt svar:</strong> {{ session.reveal.correct_answer }}</p>
         <p><strong>Spørgsmål:</strong> {{ session.reveal.prompt }}</p>
@@ -221,6 +221,10 @@ export class PlayerShellComponent implements OnInit, OnDestroy {
     return isPlayerGameplayActionAllowed(this.session as any, 'submitGuess');
   }
 
+  get showRevealPanel(): boolean {
+    return Boolean(this.session?.reveal && (this.gameplayPhase === 'reveal' || this.gameplayPhase === 'scoreboard'));
+  }
+
   private readonly handleOnline = (): void => {
     this.connectionState = 'reconnecting';
     void this.retryReconnect();
@@ -469,7 +473,7 @@ export class PlayerShellComponent implements OnInit, OnDestroy {
       return;
     }
 
-    const phase = this.session.session.status || 'lobby';
+    const phase = this.gameplayPhase ?? this.session.session.status ?? 'lobby';
     const code = this.normalizeCode(this.session.session.code || this.sessionCode);
     if (!code) {
       return;

frontend/src/api/mappers.ts

@@ -195,6 +195,7 @@ function mapSessionDetail(payload: unknown): SessionDetailResponse {
     reveal,
     phase_view_model: {
       status: readString(phase, 'status', 'session_detail.phase_view_model'),
+      current_phase: typeof phase.current_phase === 'string' ? phase.current_phase : undefined,
       round_number: readNumber(phase, 'round_number', 'session_detail.phase_view_model'),
       players_count: readNumber(phase, 'players_count', 'session_detail.phase_view_model'),
       constraints: {
@@ -203,6 +204,19 @@ function mapSessionDetail(payload: unknown): SessionDetailResponse {
         min_players_reached: readBoolean(constraints, 'min_players_reached', 'session_detail.phase_view_model.constraints'),
         max_players_allowed: readBoolean(constraints, 'max_players_allowed', 'session_detail.phase_view_model.constraints')
       },
+      readiness:
+        phase.readiness && typeof phase.readiness === 'object'
+          ? {
+              question_ready:
+                typeof (phase.readiness as Record<string, unknown>).question_ready === 'boolean'
+                  ? ((phase.readiness as Record<string, unknown>).question_ready as boolean)
+                  : undefined,
+              scoreboard_ready:
+                typeof (phase.readiness as Record<string, unknown>).scoreboard_ready === 'boolean'
+                  ? ((phase.readiness as Record<string, unknown>).scoreboard_ready as boolean)
+                  : undefined,
+            }
+          : undefined,
       host: {
         can_start_round: readBoolean(host, 'can_start_round', 'session_detail.phase_view_model.host'),
         can_show_question: readBoolean(host, 'can_show_question', 'session_detail.phase_view_model.host'),

frontend/src/api/types.ts

@@ -32,6 +32,7 @@ export interface SessionRoundQuestion {
 
 export interface PhaseViewModel {
   status: string;
+  current_phase?: string;
   round_number: number;
   players_count: number;
   constraints: {
@@ -40,6 +41,10 @@ export interface PhaseViewModel {
     min_players_reached: boolean;
     max_players_allowed: boolean;
   };
+  readiness?: {
+    question_ready?: boolean;
+    scoreboard_ready?: boolean;
+  };
   host: {
     can_start_round: boolean;
     can_show_question: boolean;

fupogfakta/migrations/0007_roundconfig_started_from_scoreboard.py

@@ -0,0 +1,18 @@
+# Generated by Django 6.0.2 on 2026-03-17 08:24
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fupogfakta', '0006_merge_20260315_1249'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='roundconfig',
+            name='started_from_scoreboard',
+            field=models.BooleanField(default=False),
+        ),
+    ]

fupogfakta/models.py

@@ -83,6 +83,7 @@ class RoundConfig(models.Model):
     points_bluff = models.IntegerField(default=2)
     lie_seconds = models.PositiveIntegerField(default=45)
     guess_seconds = models.PositiveIntegerField(default=30)
+    started_from_scoreboard = models.BooleanField(default=False)
 
     class Meta:
         unique_together = (("session", "number"),)

fupogfakta/payloads.py

@@ -13,6 +13,19 @@ def build_player_ref(player: Player | None) -> dict | None:
     }
 
 
+def build_round_question_payload(round_question: RoundQuestion | None) -> dict | None:
+    if round_question is None:
+        return None
+
+    return {
+        "id": round_question.id,
+        "round_number": round_question.round_number,
+        "prompt": round_question.question.prompt,
+        "shown_at": round_question.shown_at.isoformat(),
+        "answers": [{"text": text} for text in (round_question.mixed_answers or [])],
+    }
+
+
 def build_reveal_payload(round_question: RoundQuestion | None) -> dict | None:
     if round_question is None:
         return None
@@ -68,3 +81,195 @@ def build_lie_started_payload(session: GameSession, round_config: RoundConfig, r
         "lie_deadline_at": lie_deadline_at.isoformat(),
         "lie_seconds": round_config.lie_seconds,
     }
+
+
+def build_phase_view_model(session: GameSession, *, players_count: int, has_round_question: bool) -> dict:
+    status = session.status
+    in_lobby = status == GameSession.Status.LOBBY
+    in_lie = status == GameSession.Status.LIE
+    in_guess = status == GameSession.Status.GUESS
+    in_scoreboard = status == GameSession.Status.SCOREBOARD
+    in_finished = status == GameSession.Status.FINISHED
+
+    min_players_reached = players_count >= 3
+    max_players_allowed = players_count <= 5
+
+    return {
+        "status": status,
+        "current_phase": status,
+        "round_number": session.current_round,
+        "players_count": players_count,
+        "constraints": {
+            "min_players_to_start": 3,
+            "max_players_mvp": 5,
+            "min_players_reached": min_players_reached,
+            "max_players_allowed": max_players_allowed,
+        },
+        "readiness": {
+            "question_ready": has_round_question,
+            "scoreboard_ready": status in {GameSession.Status.REVEAL, GameSession.Status.SCOREBOARD, GameSession.Status.FINISHED},
+            "can_advance_to_next_round": in_scoreboard,
+        },
+        "host": {
+            "can_start_round": in_lobby and min_players_reached and max_players_allowed,
+            "can_show_question": False,
+            "can_mix_answers": False,
+            "can_calculate_scores": False,
+            "can_reveal_scoreboard": False,
+            "can_start_next_round": in_scoreboard,
+            "can_finish_game": in_scoreboard,
+        },
+        "player": {
+            "can_join": status in {
+                GameSession.Status.LOBBY,
+                GameSession.Status.LIE,
+                GameSession.Status.GUESS,
+                GameSession.Status.REVEAL,
+                GameSession.Status.SCOREBOARD,
+            },
+            "can_submit_lie": in_lie and has_round_question,
+            "can_submit_guess": in_guess and has_round_question,
+            "can_view_final_result": in_finished,
+        },
+    }
+
+
+def build_session_detail_gameplay_payload(
+    session: GameSession,
+    *,
+    current_round_question: RoundQuestion | None,
+    players_count: int,
+) -> dict:
+    return {
+        "round_question": build_round_question_payload(current_round_question),
+        "reveal": build_reveal_payload(current_round_question)
+        if session.status in {GameSession.Status.REVEAL, GameSession.Status.SCOREBOARD} and current_round_question
+        else None,
+        "scoreboard": build_scoreboard_phase_event(session)["payload"]["leaderboard"]
+        if session.status in {GameSession.Status.SCOREBOARD, GameSession.Status.FINISHED}
+        else None,
+        "phase_view_model": build_phase_view_model(
+            session,
+            players_count=players_count,
+            has_round_question=bool(current_round_question),
+        ),
+    }
+
+
+def build_start_round_response(
+    session: GameSession,
+    round_config: RoundConfig,
+    round_question: RoundQuestion,
+) -> dict:
+    lie_started_payload = build_lie_started_payload(session, round_config, round_question)
+    return {
+        "session": {
+            "code": session.code,
+            "status": session.status,
+            "current_round": session.current_round,
+        },
+        "round": {
+            "number": round_config.number,
+            "category": {
+                "slug": round_config.category.slug,
+                "name": round_config.category.name,
+            },
+        },
+        "round_question": {
+            "id": round_question.id,
+            "prompt": round_question.question.prompt,
+            "round_number": round_question.round_number,
+            "shown_at": round_question.shown_at.isoformat(),
+            "lie_deadline_at": lie_started_payload["lie_deadline_at"],
+        },
+        "config": {
+            "lie_seconds": round_config.lie_seconds,
+        },
+    }
+
+
+def build_question_shown_payload(round_question: RoundQuestion, lie_deadline_at: str, lie_seconds: int) -> dict:
+    return {
+        "round_question_id": round_question.id,
+        "prompt": round_question.question.prompt,
+        "shown_at": round_question.shown_at.isoformat(),
+        "lie_deadline_at": lie_deadline_at,
+        "lie_seconds": lie_seconds,
+    }
+
+
+def build_question_shown_response(round_question: RoundQuestion, lie_deadline_at: str, lie_seconds: int) -> dict:
+    return {
+        "round_question": {
+            "id": round_question.id,
+            "prompt": round_question.question.prompt,
+            "round_number": round_question.round_number,
+            "shown_at": round_question.shown_at.isoformat(),
+            "lie_deadline_at": lie_deadline_at,
+        },
+        "config": {
+            "lie_seconds": lie_seconds,
+        },
+    }
+
+
+def build_start_next_round_response(
+    session: GameSession,
+    round_config: RoundConfig,
+    round_question: RoundQuestion,
+) -> dict:
+    return build_start_round_response(session, round_config, round_question)
+
+
+def build_start_next_round_phase_event(
+    session: GameSession,
+    round_config: RoundConfig,
+    round_question: RoundQuestion,
+) -> dict:
+    return {
+        "name": "phase.lie_started",
+        "payload": build_lie_started_payload(session, round_config, round_question),
+    }
+
+
+def build_scoreboard_phase_event(session: GameSession, leaderboard: list[dict] | None = None) -> dict:
+    return {
+        "name": "phase.scoreboard",
+        "payload": {
+            "leaderboard": leaderboard if leaderboard is not None else build_leaderboard(session),
+            "current_round": session.current_round,
+        },
+    }
+
+
+def build_reveal_scoreboard_response(session: GameSession, leaderboard: list[dict]) -> dict:
+    return {
+        "session": {
+            "code": session.code,
+            "status": session.status,
+            "current_round": session.current_round,
+        },
+        "leaderboard": leaderboard,
+    }
+
+
+def build_finish_game_phase_event(session: GameSession) -> dict:
+    leaderboard = build_leaderboard(session)
+    winner = leaderboard[0] if leaderboard else None
+    return {
+        "name": "phase.game_over",
+        "payload": {"winner": winner, "leaderboard": leaderboard},
+    }
+
+
+def build_finish_game_response(session: GameSession) -> dict:
+    finish_event = build_finish_game_phase_event(session)
+    return {
+        "session": {
+            "code": session.code,
+            "status": GameSession.Status.FINISHED,
+            "current_round": session.current_round,
+        },
+        "winner": finish_event["payload"]["winner"],
+        "leaderboard": finish_event["payload"]["leaderboard"],
+    }

fupogfakta/services.py

@@ -1,11 +1,59 @@
 import random
+from datetime import timedelta
+from dataclasses import dataclass
+from typing import Any
 
-from .models import GameSession, Player, Question, RoundConfig, RoundQuestion, ScoreEvent
+from django.db import transaction
+from django.utils import timezone
+
+from .models import Category, GameSession, Guess, LieAnswer, Player, Question, RoundConfig, RoundQuestion, ScoreEvent
+from .payloads import (
+    build_finish_game_phase_event,
+    build_finish_game_response,
+    build_lie_started_payload,
+    build_question_shown_payload,
+    build_question_shown_response,
+    build_reveal_scoreboard_response,
+    build_scoreboard_phase_event,
+    build_start_next_round_phase_event,
+    build_start_next_round_response,
+    build_start_round_response,
+)
 
 
-def get_current_round_question(session: GameSession) -> RoundQuestion | None:
+@dataclass(frozen=True)
+class RoundTransitionResult:
+    session: GameSession
+    round_config: RoundConfig
+    round_question: RoundQuestion
+    should_broadcast: bool
+    response_payload: dict[str, Any]
+    phase_event_name: str | None = None
+    phase_event_payload: dict[str, Any] | None = None
+
+
+@dataclass(frozen=True)
+class FinishGameResult:
+    session: GameSession
+    should_broadcast: bool
+    response_payload: dict[str, Any]
+    phase_event_name: str | None = None
+    phase_event_payload: dict[str, Any] | None = None
+
+
+@dataclass(frozen=True)
+class ScoreboardTransitionResult:
+    session: GameSession
+    leaderboard: list[dict]
+    should_broadcast: bool
+    response_payload: dict[str, Any] | None = None
+    phase_event_name: str | None = None
+    phase_event_payload: dict[str, Any] | None = None
+
+
+def get_round_question(session: GameSession, round_number: int) -> RoundQuestion | None:
     return (
-        RoundQuestion.objects.filter(session=session, round_number=session.current_round)
+        RoundQuestion.objects.filter(session=session, round_number=round_number)
         .select_related("question")
         .order_by("-id")
         .first()
@@ -13,9 +61,37 @@ def get_current_round_question(session: GameSession) -> RoundQuestion | None:
 
 
 
-def select_round_question(session: GameSession, round_config: RoundConfig) -> RoundQuestion:
-    existing_round_question = get_current_round_question(session)
-    if existing_round_question is not None:
+def get_current_round_question(session: GameSession) -> RoundQuestion | None:
+    return get_round_question(session, session.current_round)
+
+
+
+def reset_round_question_bootstrap_state(round_question: RoundQuestion) -> RoundQuestion:
+    Guess.objects.filter(round_question=round_question).delete()
+    LieAnswer.objects.filter(round_question=round_question).delete()
+
+    update_fields: list[str] = []
+    if round_question.mixed_answers:
+        round_question.mixed_answers = []
+        update_fields.append("mixed_answers")
+
+    round_question.shown_at = timezone.now()
+    update_fields.append("shown_at")
+
+    round_question.save(update_fields=update_fields)
+    return round_question
+
+
+
+def select_round_question(
+    session: GameSession,
+    round_config: RoundConfig,
+    *,
+    round_number: int | None = None,
+) -> RoundQuestion:
+    target_round_number = session.current_round if round_number is None else round_number
+    existing_round_question = get_round_question(session, target_round_number)
+    if existing_round_question is not None and existing_round_question.question.category_id == round_config.category_id:
         return existing_round_question
 
     used_question_ids = RoundQuestion.objects.filter(session=session).values_list("question_id", flat=True)
@@ -28,9 +104,15 @@ def select_round_question(session: GameSession, round_config: RoundConfig) -> Ro
         raise ValueError("no_available_questions")
 
     question = random.choice(list(available_questions))
+    if existing_round_question is not None:
+        existing_round_question.question = question
+        existing_round_question.correct_answer = question.correct_answer
+        existing_round_question.save(update_fields=["question", "correct_answer"])
+        return existing_round_question
+
     return RoundQuestion.objects.create(
         session=session,
-        round_number=session.current_round,
+        round_number=target_round_number,
         question=question,
         correct_answer=question.correct_answer,
     )
@@ -61,6 +143,288 @@ def prepare_mixed_answers(round_question: RoundQuestion) -> list[str]:
 
 
 
+
+
+def start_round(session: GameSession, category_slug: str) -> RoundTransitionResult:
+    try:
+        category = Category.objects.get(slug=category_slug, is_active=True)
+    except Category.DoesNotExist:
+        raise ValueError("category_not_found")
+
+    if not Question.objects.filter(category=category, is_active=True).exists():
+        raise ValueError("category_has_no_questions")
+
+    with transaction.atomic():
+        locked_session = GameSession.objects.select_for_update().get(pk=session.pk)
+        if locked_session.status != GameSession.Status.LOBBY:
+            raise ValueError("round_start_invalid_phase")
+
+        if RoundConfig.objects.filter(session=locked_session, number=locked_session.current_round).exists():
+            raise ValueError("round_already_configured")
+
+        round_config = RoundConfig(
+            session=locked_session,
+            number=locked_session.current_round,
+            category=category,
+        )
+
+        round_question = select_round_question(locked_session, round_config)
+
+        round_config.save()
+        locked_session.status = GameSession.Status.LIE
+        locked_session.save(update_fields=["status"])
+
+    phase_event = {
+        "name": "phase.lie_started",
+        "payload": build_lie_started_payload(locked_session, round_config, round_question),
+    }
+    return RoundTransitionResult(
+        session=locked_session,
+        round_config=round_config,
+        round_question=round_question,
+        should_broadcast=True,
+        response_payload=build_start_round_response(locked_session, round_config, round_question),
+        phase_event_name=phase_event["name"],
+        phase_event_payload=phase_event["payload"],
+    )
+
+
+def show_question(session: GameSession) -> RoundTransitionResult:
+    if session.status != GameSession.Status.LIE:
+        raise ValueError("show_question_invalid_phase")
+
+    try:
+        round_config = RoundConfig.objects.get(session=session, number=session.current_round)
+    except RoundConfig.DoesNotExist:
+        raise ValueError("round_config_missing")
+
+    round_question = get_current_round_question(session)
+    if round_question is None:
+        round_question = select_round_question(session, round_config)
+
+    lie_deadline_at = round_question.shown_at + timedelta(seconds=round_config.lie_seconds)
+    lie_deadline_iso = lie_deadline_at.isoformat()
+    phase_event = {
+        "name": "phase.question_shown",
+        "payload": build_question_shown_payload(round_question, lie_deadline_iso, round_config.lie_seconds),
+    }
+    return RoundTransitionResult(
+        session=session,
+        round_config=round_config,
+        round_question=round_question,
+        should_broadcast=True,
+        response_payload=build_question_shown_response(round_question, lie_deadline_iso, round_config.lie_seconds),
+        phase_event_name=phase_event["name"],
+        phase_event_payload=phase_event["payload"],
+    )
+
+def start_next_round(session: GameSession) -> RoundTransitionResult:
+    with transaction.atomic():
+        locked_session = GameSession.objects.select_for_update().get(pk=session.pk)
+        next_round_config = None
+        round_question = None
+        should_broadcast = False
+
+        phase_event_name = None
+        phase_event_payload = None
+
+        if locked_session.status == GameSession.Status.SCOREBOARD:
+            previous_round_config = RoundConfig.objects.filter(
+                session=locked_session,
+                number=locked_session.current_round,
+            ).select_related("category").first()
+            if previous_round_config is None:
+                raise ValueError("round_config_missing")
+
+            next_round_number = locked_session.current_round + 1
+            next_round_config, _created = RoundConfig.objects.get_or_create(
+                session=locked_session,
+                number=next_round_number,
+                defaults={
+                    "category": previous_round_config.category,
+                    "lie_seconds": previous_round_config.lie_seconds,
+                    "guess_seconds": previous_round_config.guess_seconds,
+                    "points_correct": previous_round_config.points_correct,
+                    "points_bluff": previous_round_config.points_bluff,
+                    "started_from_scoreboard": True,
+                },
+            )
+            round_config_update_fields: list[str] = []
+            if next_round_config.category_id != previous_round_config.category_id:
+                next_round_config.category = previous_round_config.category
+                round_config_update_fields.append("category")
+            if next_round_config.lie_seconds != previous_round_config.lie_seconds:
+                next_round_config.lie_seconds = previous_round_config.lie_seconds
+                round_config_update_fields.append("lie_seconds")
+            if next_round_config.guess_seconds != previous_round_config.guess_seconds:
+                next_round_config.guess_seconds = previous_round_config.guess_seconds
+                round_config_update_fields.append("guess_seconds")
+            if next_round_config.points_correct != previous_round_config.points_correct:
+                next_round_config.points_correct = previous_round_config.points_correct
+                round_config_update_fields.append("points_correct")
+            if next_round_config.points_bluff != previous_round_config.points_bluff:
+                next_round_config.points_bluff = previous_round_config.points_bluff
+                round_config_update_fields.append("points_bluff")
+            if not next_round_config.started_from_scoreboard:
+                next_round_config.started_from_scoreboard = True
+                round_config_update_fields.append("started_from_scoreboard")
+            if round_config_update_fields:
+                next_round_config.save(update_fields=round_config_update_fields)
+
+            locked_session.current_round = next_round_number
+
+            round_question = reset_round_question_bootstrap_state(
+                select_round_question(locked_session, next_round_config, round_number=next_round_number)
+            )
+
+            locked_session.status = GameSession.Status.LIE
+            locked_session.save(update_fields=["current_round", "status"])
+            should_broadcast = True
+            phase_event = build_start_next_round_phase_event(locked_session, next_round_config, round_question)
+            phase_event_name = phase_event["name"]
+            phase_event_payload = phase_event["payload"]
+        elif locked_session.status == GameSession.Status.LIE:
+            if locked_session.current_round <= 1:
+                raise ValueError("next_round_invalid_phase")
+
+            next_round_config = RoundConfig.objects.filter(
+                session=locked_session,
+                number=locked_session.current_round,
+            ).select_related("category").first()
+            round_question = get_current_round_question(locked_session)
+            if (
+                next_round_config is None
+                or not next_round_config.started_from_scoreboard
+                or round_question is None
+            ):
+                raise ValueError("next_round_invalid_phase")
+        else:
+            raise ValueError("next_round_invalid_phase")
+
+        return RoundTransitionResult(
+            session=locked_session,
+            round_config=next_round_config,
+            round_question=round_question,
+            should_broadcast=should_broadcast,
+            response_payload=build_start_next_round_response(
+                locked_session,
+                next_round_config,
+                round_question,
+            ),
+            phase_event_name=phase_event_name,
+            phase_event_payload=phase_event_payload,
+        )
+
+
+
+def finish_game(session: GameSession) -> FinishGameResult:
+    with transaction.atomic():
+        locked_session = GameSession.objects.select_for_update().get(pk=session.pk)
+        should_broadcast = False
+        phase_event_name = None
+        phase_event_payload = None
+
+        if locked_session.status == GameSession.Status.SCOREBOARD:
+            locked_session.status = GameSession.Status.FINISHED
+            locked_session.save(update_fields=["status"])
+            should_broadcast = True
+            phase_event = build_finish_game_phase_event(locked_session)
+            phase_event_name = phase_event["name"]
+            phase_event_payload = phase_event["payload"]
+        elif locked_session.status != GameSession.Status.FINISHED:
+            raise ValueError("finish_game_invalid_phase")
+
+        return FinishGameResult(
+            session=locked_session,
+            should_broadcast=should_broadcast,
+            response_payload=build_finish_game_response(locked_session),
+            phase_event_name=phase_event_name,
+            phase_event_payload=phase_event_payload,
+        )
+
+
+
+def promote_reveal_to_scoreboard(session: GameSession) -> ScoreboardTransitionResult:
+    if session.status != GameSession.Status.REVEAL:
+        leaderboard = list(
+            Player.objects.filter(session=session)
+            .order_by("-score", "nickname")
+            .values("id", "nickname", "score")
+        )
+        return ScoreboardTransitionResult(
+            session=session,
+            leaderboard=leaderboard,
+            should_broadcast=False,
+            response_payload=build_reveal_scoreboard_response(session, leaderboard),
+        )
+
+    current_round_question = get_current_round_question(session)
+    if current_round_question is None:
+        leaderboard = list(
+            Player.objects.filter(session=session)
+            .order_by("-score", "nickname")
+            .values("id", "nickname", "score")
+        )
+        return ScoreboardTransitionResult(
+            session=session,
+            leaderboard=leaderboard,
+            should_broadcast=False,
+            response_payload=build_reveal_scoreboard_response(session, leaderboard),
+        )
+
+    players_count = Player.objects.filter(session=session).count()
+    guess_count = Guess.objects.filter(round_question=current_round_question).count()
+    has_score_events = ScoreEvent.objects.filter(
+        session=session,
+        meta__round_question_id=current_round_question.id,
+    ).exists()
+    reveal_is_resolved = has_score_events or (players_count > 0 and guess_count >= players_count)
+    if not reveal_is_resolved:
+        leaderboard = list(
+            Player.objects.filter(session=session)
+            .order_by("-score", "nickname")
+            .values("id", "nickname", "score")
+        )
+        return ScoreboardTransitionResult(
+            session=session,
+            leaderboard=leaderboard,
+            should_broadcast=False,
+            response_payload=build_reveal_scoreboard_response(session, leaderboard),
+        )
+
+    with transaction.atomic():
+        locked_session = GameSession.objects.select_for_update().get(pk=session.pk)
+        if locked_session.status != GameSession.Status.REVEAL:
+            scoreboard_session = locked_session
+            should_broadcast = False
+        else:
+            locked_session.status = GameSession.Status.SCOREBOARD
+            locked_session.save(update_fields=["status"])
+            scoreboard_session = locked_session
+            should_broadcast = True
+
+    leaderboard = list(
+        Player.objects.filter(session=scoreboard_session)
+        .order_by("-score", "nickname")
+        .values("id", "nickname", "score")
+    )
+    phase_event_name = None
+    phase_event_payload = None
+    if should_broadcast:
+        phase_event = build_scoreboard_phase_event(scoreboard_session, leaderboard)
+        phase_event_name = phase_event["name"]
+        phase_event_payload = phase_event["payload"]
+    return ScoreboardTransitionResult(
+        session=scoreboard_session,
+        leaderboard=leaderboard,
+        should_broadcast=should_broadcast,
+        response_payload=build_reveal_scoreboard_response(scoreboard_session, leaderboard),
+        phase_event_name=phase_event_name,
+        phase_event_payload=phase_event_payload,
+    )
+
+
+
 def resolve_scores(
     session: GameSession,
     round_question: RoundQuestion,

fupogfakta/tests.py

@@ -1,11 +1,27 @@
+from datetime import timedelta
 from unittest.mock import patch
 
 from django.contrib.auth import get_user_model
 from django.test import TestCase
+from django.utils import timezone
 
 from fupogfakta.models import Category, GameSession, Guess, LieAnswer, Player, Question, RoundConfig, RoundQuestion, ScoreEvent
-from fupogfakta.payloads import build_lie_started_payload, build_reveal_payload
-from fupogfakta.services import get_current_round_question, prepare_mixed_answers, resolve_scores, select_round_question
+from fupogfakta.payloads import (
+    build_lie_started_payload,
+    build_phase_view_model,
+    build_reveal_payload,
+    build_round_question_payload,
+    build_session_detail_gameplay_payload,
+)
+from fupogfakta.services import (
+    finish_game,
+    get_current_round_question,
+    prepare_mixed_answers,
+    promote_reveal_to_scoreboard,
+    resolve_scores,
+    select_round_question,
+    start_next_round,
+)
 
 User = get_user_model()
 
@@ -63,6 +79,232 @@ class FupOgFaktaExtractionSliceTests(TestCase):
         round_question.refresh_from_db()
         self.assertEqual(round_question.mixed_answers, answers)
 
+    def test_start_next_round_moves_scoreboard_transition_into_service(self):
+        self.session.status = GameSession.Status.SCOREBOARD
+        self.session.save(update_fields=["status"])
+
+        result = start_next_round(self.session)
+
+        self.session.refresh_from_db()
+        self.assertTrue(result.should_broadcast)
+        self.assertEqual(result.session.status, GameSession.Status.LIE)
+        self.assertEqual(result.session.current_round, 2)
+        self.assertEqual(result.round_config.number, 2)
+        self.assertTrue(result.round_config.started_from_scoreboard)
+        self.assertEqual(result.round_question.round_number, 2)
+
+    def test_start_next_round_rejects_plain_lie_without_scoreboard_marker(self):
+        self.session.status = GameSession.Status.LIE
+        self.session.current_round = 2
+        self.session.save(update_fields=["status", "current_round"])
+        RoundConfig.objects.create(session=self.session, number=2, category=self.category, started_from_scoreboard=False)
+        RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=self.question_two,
+            correct_answer=self.question_two.correct_answer,
+        )
+
+        with self.assertRaisesMessage(ValueError, "next_round_invalid_phase"):
+            start_next_round(self.session)
+
+    def test_start_next_round_refreshes_shown_at_for_reused_bootstrap_question(self):
+        self.session.status = GameSession.Status.SCOREBOARD
+        self.session.save(update_fields=["status"])
+        stale_shown_at = timezone.now() - timedelta(minutes=10)
+        stale_round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=self.question_two,
+            correct_answer=self.question_two.correct_answer,
+            shown_at=stale_shown_at,
+            mixed_answers=["Stale truth", "Stale lie"],
+        )
+        LieAnswer.objects.create(round_question=stale_round_question, player=self.alice, text="Stale lie")
+        Guess.objects.create(
+            round_question=stale_round_question,
+            player=self.bob,
+            selected_text="Stale truth",
+            is_correct=True,
+        )
+
+        before_transition = timezone.now()
+        result = start_next_round(self.session)
+        after_transition = timezone.now()
+
+        stale_round_question.refresh_from_db()
+        self.assertEqual(result.round_question.id, stale_round_question.id)
+        self.assertGreaterEqual(stale_round_question.shown_at, before_transition)
+        self.assertLessEqual(stale_round_question.shown_at, after_transition)
+        self.assertNotEqual(stale_round_question.shown_at, stale_shown_at)
+        self.assertEqual(result.response_payload["round_question"]["shown_at"], stale_round_question.shown_at.isoformat())
+        expected_deadline = stale_round_question.shown_at + timedelta(seconds=result.round_config.lie_seconds)
+        self.assertEqual(result.response_payload["round_question"]["lie_deadline_at"], expected_deadline.isoformat())
+        self.assertGreater(expected_deadline, before_transition)
+        self.assertEqual(stale_round_question.mixed_answers, [])
+        self.assertEqual(stale_round_question.lies.count(), 0)
+        self.assertEqual(stale_round_question.guesses.count(), 0)
+
+    def test_start_next_round_reuses_existing_bootstrap_round_config_with_fresh_canonical_values(self):
+        self.session.status = GameSession.Status.SCOREBOARD
+        self.session.save(update_fields=["status"])
+        stale_category = Category.objects.create(name="Sport", slug="sport", is_active=True)
+        stale_round_config = RoundConfig.objects.create(
+            session=self.session,
+            number=2,
+            category=stale_category,
+            lie_seconds=12,
+            guess_seconds=18,
+            points_correct=9,
+            points_bluff=7,
+            started_from_scoreboard=False,
+        )
+        stale_round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=self.question_two,
+            correct_answer=self.question_two.correct_answer,
+            shown_at=timezone.now() - timedelta(minutes=10),
+            mixed_answers=["Stale truth"],
+        )
+
+        result = start_next_round(self.session)
+
+        stale_round_config.refresh_from_db()
+        stale_round_question.refresh_from_db()
+        self.assertEqual(result.round_config.id, stale_round_config.id)
+        self.assertEqual(RoundConfig.objects.filter(session=self.session, number=2).count(), 1)
+        self.assertEqual(stale_round_config.category_id, self.round_config.category_id)
+        self.assertEqual(stale_round_config.lie_seconds, self.round_config.lie_seconds)
+        self.assertEqual(stale_round_config.guess_seconds, self.round_config.guess_seconds)
+        self.assertEqual(stale_round_config.points_correct, self.round_config.points_correct)
+        self.assertEqual(stale_round_config.points_bluff, self.round_config.points_bluff)
+        self.assertTrue(stale_round_config.started_from_scoreboard)
+        self.assertEqual(result.round_question.id, stale_round_question.id)
+        self.assertEqual(stale_round_question.mixed_answers, [])
+
+    def test_start_next_round_repairs_reused_bootstrap_question_when_category_drifted(self):
+        self.session.status = GameSession.Status.SCOREBOARD
+        self.session.save(update_fields=["status"])
+        RoundQuestion.objects.create(
+            session=self.session,
+            round_number=1,
+            question=self.question_one,
+            correct_answer=self.question_one.correct_answer,
+        )
+        stale_category = Category.objects.create(name="Sport drift", slug="sport-drift", is_active=True)
+        stale_question = Question.objects.create(
+            category=stale_category,
+            prompt="Hvem vandt EM i 1992?",
+            correct_answer="Danmark",
+            is_active=True,
+        )
+        stale_round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=stale_question,
+            correct_answer=stale_question.correct_answer,
+            shown_at=timezone.now() - timedelta(minutes=10),
+            mixed_answers=["Stale truth", "Stale lie"],
+        )
+        LieAnswer.objects.create(round_question=stale_round_question, player=self.alice, text="Tyskland")
+        Guess.objects.create(
+            round_question=stale_round_question,
+            player=self.bob,
+            selected_text="Stale truth",
+            is_correct=True,
+        )
+
+        result = start_next_round(self.session)
+
+        stale_round_question.refresh_from_db()
+        self.assertEqual(result.round_question.id, stale_round_question.id)
+        self.assertEqual(stale_round_question.question.category_id, self.round_config.category_id)
+        self.assertEqual(stale_round_question.question_id, self.question_two.id)
+        self.assertEqual(stale_round_question.correct_answer, self.question_two.correct_answer)
+        self.assertEqual(stale_round_question.mixed_answers, [])
+        self.assertEqual(stale_round_question.lies.count(), 0)
+        self.assertEqual(stale_round_question.guesses.count(), 0)
+
+    def test_start_next_round_does_not_reuse_previous_round_question_when_category_matches(self):
+        self.session.status = GameSession.Status.SCOREBOARD
+        self.session.save(update_fields=["status"])
+        previous_round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=1,
+            question=self.question_one,
+            correct_answer=self.question_one.correct_answer,
+            mixed_answers=["1989", "1991"],
+        )
+        LieAnswer.objects.create(round_question=previous_round_question, player=self.alice, text="1991")
+        Guess.objects.create(
+            round_question=previous_round_question,
+            player=self.bob,
+            selected_text="1991",
+            is_correct=False,
+            fooled_player=self.alice,
+        )
+
+        result = start_next_round(self.session)
+
+        previous_round_question.refresh_from_db()
+        self.session.refresh_from_db()
+        self.assertEqual(self.session.current_round, 2)
+        self.assertEqual(result.round_question.round_number, 2)
+        self.assertNotEqual(result.round_question.id, previous_round_question.id)
+        self.assertEqual(result.round_question.question_id, self.question_two.id)
+        self.assertEqual(previous_round_question.round_number, 1)
+        self.assertEqual(previous_round_question.question_id, self.question_one.id)
+        self.assertEqual(previous_round_question.mixed_answers, ["1989", "1991"])
+        self.assertEqual(previous_round_question.lies.count(), 1)
+        self.assertEqual(previous_round_question.guesses.count(), 1)
+
+    def test_finish_game_moves_scoreboard_transition_into_service(self):
+        self.session.status = GameSession.Status.SCOREBOARD
+        self.session.save(update_fields=["status"])
+
+        result = finish_game(self.session)
+
+        self.session.refresh_from_db()
+        self.assertTrue(result.should_broadcast)
+        self.assertEqual(result.session.status, GameSession.Status.FINISHED)
+        self.assertEqual(self.session.status, GameSession.Status.FINISHED)
+
+    def test_promote_reveal_to_scoreboard_moves_transition_into_service(self):
+        round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=1,
+            question=self.question_one,
+            correct_answer=self.question_one.correct_answer,
+        )
+        self.session.status = GameSession.Status.REVEAL
+        self.session.save(update_fields=["status"])
+
+        LieAnswer.objects.create(round_question=round_question, player=self.alice, text="Elbil")
+        Guess.objects.create(
+            round_question=round_question,
+            player=self.bob,
+            selected_text="Elbil",
+            is_correct=False,
+            fooled_player=self.alice,
+        )
+        ScoreEvent.objects.create(
+            session=self.session,
+            player=self.alice,
+            delta=5,
+            reason="bluff_success",
+            meta={"round_question_id": round_question.id},
+        )
+        self.alice.score = 5
+        self.alice.save(update_fields=["score"])
+
+        result = promote_reveal_to_scoreboard(self.session)
+
+        self.session.refresh_from_db()
+        self.assertTrue(result.should_broadcast)
+        self.assertEqual(result.session.status, GameSession.Status.SCOREBOARD)
+        self.assertEqual(result.leaderboard[0]["nickname"], self.alice.nickname)
+
     def test_resolve_scores_applies_correct_and_bluff_points(self):
         round_question = RoundQuestion.objects.create(
             session=self.session,
@@ -117,11 +359,52 @@ class FupOgFaktaExtractionSliceTests(TestCase):
             fooled_player=self.bob,
         )
 
+        round_question_payload = build_round_question_payload(round_question)
         lie_payload = build_lie_started_payload(self.session, self.round_config, round_question)
         reveal_payload = build_reveal_payload(round_question)
+        phase_view_model = build_phase_view_model(
+            self.session,
+            players_count=3,
+            has_round_question=True,
+        )
 
+        self.assertEqual(round_question_payload["prompt"], self.question_one.prompt)
+        self.assertEqual(round_question_payload["answers"], [])
         self.assertEqual(lie_payload["category"], {"slug": self.category.slug, "name": self.category.name})
         self.assertEqual(lie_payload["round_question_id"], round_question.id)
         self.assertEqual(reveal_payload["correct_answer"], "1989")
         self.assertEqual(reveal_payload["lies"][0]["player_id"], lie.player_id)
         self.assertEqual(reveal_payload["guesses"][0]["fooled_player_nickname"], self.bob.nickname)
+        self.assertTrue(phase_view_model["host"]["can_start_round"])
+        self.assertFalse(phase_view_model["host"]["can_finish_game"])
+
+    def test_build_session_detail_gameplay_payload_keeps_session_detail_semantics_in_cartridge(self):
+        self.session.status = GameSession.Status.SCOREBOARD
+        self.session.save(update_fields=["status"])
+        round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=1,
+            question=self.question_one,
+            correct_answer=self.question_one.correct_answer,
+        )
+        lie = LieAnswer.objects.create(round_question=round_question, player=self.bob, text="1991")
+        Guess.objects.create(
+            round_question=round_question,
+            player=self.alice,
+            selected_text="1991",
+            is_correct=False,
+            fooled_player=self.bob,
+        )
+
+        gameplay_payload = build_session_detail_gameplay_payload(
+            self.session,
+            current_round_question=round_question,
+            players_count=3,
+        )
+
+        self.assertEqual(gameplay_payload["round_question"]["id"], round_question.id)
+        self.assertEqual(gameplay_payload["reveal"]["lies"][0]["player_id"], lie.player_id)
+        self.assertEqual(gameplay_payload["scoreboard"], [{"id": self.alice.id, "nickname": self.alice.nickname, "score": self.alice.score}, {"id": self.bob.id, "nickname": self.bob.nickname, "score": self.bob.score}, {"id": self.clara.id, "nickname": self.clara.nickname, "score": self.clara.score}])
+        self.assertEqual(gameplay_payload["phase_view_model"]["status"], GameSession.Status.SCOREBOARD)
+        self.assertTrue(gameplay_payload["phase_view_model"]["host"]["can_start_next_round"])
+        self.assertTrue(gameplay_payload["phase_view_model"]["host"]["can_finish_game"])

lobby/management/commands/smoke_staging.py

@@ -10,7 +10,7 @@ from fupogfakta.models import Category, GameSession, Player, Question, RoundQues
 
 
 class Command(BaseCommand):
-    help = "Run minimal staging smoke flow for lobby gameplay"
+    help = "Run canonical gameplay smoke/regression flow for bluff -> guess -> reveal -> scoreboard"
 
     def add_arguments(self, parser):
         parser.add_argument(
@@ -18,6 +18,26 @@ class Command(BaseCommand):
             help="Optional path to write smoke result artifact as JSON",
         )
 
+    def _fail(self, step: str, detail: str, payload=None):
+        message = f"{step} failed: {detail}"
+        if payload is not None:
+            message += f" | payload={json.dumps(payload, sort_keys=True)}"
+        raise CommandError(message)
+
+    def _expect_status(self, response, expected_status: int, step: str):
+        if response.status_code != expected_status:
+            try:
+                payload = response.json()
+            except ValueError:
+                payload = {"raw": response.content.decode("utf-8", errors="replace")}
+            self._fail(step, f"expected HTTP {expected_status}, got {response.status_code}", payload)
+        return response.json()
+
+    def _expect_session_status(self, payload: dict, expected_status: str, step: str):
+        actual_status = payload.get("session", {}).get("status")
+        if actual_status != expected_status:
+            self._fail(step, f"expected session.status={expected_status}, got {actual_status}", payload)
+
     def handle(self, *args, **options):
         GameSession.objects.all().delete()
         Player.objects.all().delete()
@@ -30,11 +50,14 @@ class Command(BaseCommand):
         category.is_active = True
         category.save(update_fields=["is_active"])
 
-        Question.objects.get_or_create(
+        question, _ = Question.objects.get_or_create(
             category=category,
             prompt="Smoke prompt?",
             defaults={"correct_answer": "Correct", "is_active": True},
         )
+        if not question.is_active:
+            question.is_active = True
+            question.save(update_fields=["is_active"])
 
         User = get_user_model()
         host, _ = User.objects.get_or_create(username="smoke-host")
@@ -42,111 +65,254 @@ class Command(BaseCommand):
         host.is_staff = True
         host.save()
 
+        artifact = {
+            "ok": True,
+            "command": "python manage.py smoke_staging --artifact <path>",
+            "generated_at": datetime.now(timezone.utc).isoformat(),
+            "question": {
+                "prompt": question.prompt,
+                "correct_answer": question.correct_answer,
+            },
+            "steps": [],
+        }
+
         host_client = Client()
         host_client.force_login(host)
 
-        create_res = host_client.post("/lobby/sessions/create", content_type="application/json")
-        if create_res.status_code != 201:
-            raise CommandError(f"create_session failed: {create_res.status_code} {create_res.content!r}")
-
-        code = create_res.json()["session"]["code"]
+        create_payload = self._expect_status(
+            host_client.post("/lobby/sessions/create", content_type="application/json"),
+            201,
+            "create_session",
+        )
+        code = create_payload["session"]["code"]
+        artifact["session_code"] = code
+        artifact["steps"].append(
+            {
+                "step": "create_session",
+                "session_status": create_payload["session"]["status"],
+            }
+        )
 
         players = []
         for nickname in ["P1", "P2", "P3"]:
-            join_res = Client().post(
-                "/lobby/sessions/join",
-                data=json.dumps({"code": code, "nickname": nickname}),
-                content_type="application/json",
+            join_payload = self._expect_status(
+                Client().post(
+                    "/lobby/sessions/join",
+                    data=json.dumps({"code": code, "nickname": nickname}),
+                    content_type="application/json",
+                ),
+                201,
+                f"join_session[{nickname}]",
             )
-            if join_res.status_code != 201:
-                raise CommandError(f"join_session failed for {nickname}: {join_res.status_code}")
-            players.append(join_res.json()["player"])
-
-        start_res = host_client.post(
-            f"/lobby/sessions/{code}/rounds/start",
-            data=json.dumps({"category_slug": category.slug}),
-            content_type="application/json",
+            players.append(join_payload["player"])
+        artifact["players"] = [player["nickname"] for player in players]
+        artifact["steps"].append(
+            {
+                "step": "join_players",
+                "players_count": len(players),
+            }
         )
-        if start_res.status_code != 201:
-            raise CommandError(f"start_round failed: {start_res.status_code}")
 
-        round_question_id = start_res.json()["round_question"]["id"]
+        start_payload = self._expect_status(
+            host_client.post(
+                f"/lobby/sessions/{code}/rounds/start",
+                data=json.dumps({"category_slug": category.slug}),
+                content_type="application/json",
+            ),
+            201,
+            "start_round",
+        )
+        self._expect_session_status(start_payload, GameSession.Status.LIE, "start_round")
+
+        round_question_id = start_payload["round_question"]["id"]
+        artifact["round_question_id"] = round_question_id
+        artifact["steps"].append(
+            {
+                "step": "start_round",
+                "session_status": start_payload["session"]["status"],
+                "round_question_id": round_question_id,
+            }
+        )
 
         answers = []
+        lie_transition_payload = None
         for player in players:
-            nick = player["nickname"]
-            lie_res = Client().post(
-                f"/lobby/sessions/{code}/questions/{round_question_id}/lies/submit",
-                data=json.dumps(
-                    {
-                        "player_id": player["id"],
-                        "session_token": player["session_token"],
-                        "text": f"Lie from {nick}",
-                    }
+            nickname = player["nickname"]
+            lie_payload = self._expect_status(
+                Client().post(
+                    f"/lobby/sessions/{code}/questions/{round_question_id}/lies/submit",
+                    data=json.dumps(
+                        {
+                            "player_id": player["id"],
+                            "session_token": player["session_token"],
+                            "text": f"Lie from {nickname}",
+                        }
+                    ),
+                    content_type="application/json",
                 ),
-                content_type="application/json",
+                201,
+                f"submit_lie[{nickname}]",
             )
-            if lie_res.status_code != 201:
-                raise CommandError(f"submit_lie failed for {nick}: {lie_res.status_code}")
-            if lie_res.json().get("answers"):
-                answers = lie_res.json()["answers"]
+            if lie_payload.get("answers"):
+                answers = lie_payload["answers"]
+                lie_transition_payload = lie_payload
 
         if not answers:
-            detail_res = host_client.get(f"/lobby/sessions/{code}")
-            if detail_res.status_code != 200:
-                raise CommandError(f"session_detail after lies failed: {detail_res.status_code}")
-            answers = detail_res.json().get("round_question", {}).get("answers", [])
+            detail_payload = self._expect_status(host_client.get(f"/lobby/sessions/{code}"), 200, "session_detail_after_lies")
+            answers = detail_payload.get("round_question", {}).get("answers", [])
+            self._expect_session_status(detail_payload, GameSession.Status.GUESS, "session_detail_after_lies")
+            lie_transition_payload = detail_payload
 
         if not answers:
-            raise CommandError("canonical lie->guess transition returned empty answers")
+            self._fail("auto_guess_transition", "canonical lie->guess transition returned empty answers")
 
-        for player in players:
-            nick = player["nickname"]
-            selected = next((a for a in answers if a.get("player_id") != player["id"]), answers[0])
-            guess_res = Client().post(
-                f"/lobby/sessions/{code}/questions/{round_question_id}/guesses/submit",
-                data=json.dumps(
-                    {
-                        "player_id": player["id"],
-                        "session_token": player["session_token"],
-                        "selected_text": selected["text"],
-                    }
-                ),
-                content_type="application/json",
+        if not any(answer.get("text") == question.correct_answer for answer in answers):
+            self._fail("auto_guess_transition", "mixed answers missing correct answer", {"answers": answers})
+        if len(answers) < len(players) + 1:
+            self._fail(
+                "auto_guess_transition",
+                "mixed answers shorter than expected bluff set",
+                {"answers": answers, "players_count": len(players)},
             )
-            if guess_res.status_code != 201:
-                raise CommandError(f"submit_guess failed for {nick}: {guess_res.status_code}")
 
-        detail_res = host_client.get(f"/lobby/sessions/{code}")
-        if detail_res.status_code != 200:
-            raise CommandError(f"session_detail after guesses failed: {detail_res.status_code}")
-        if detail_res.json()["session"]["status"] != GameSession.Status.SCOREBOARD:
-            raise CommandError("canonical guess->reveal->scoreboard transition did not reach scoreboard")
+        self._expect_session_status(lie_transition_payload, GameSession.Status.GUESS, "auto_guess_transition")
+        artifact["steps"].append(
+            {
+                "step": "auto_guess_transition",
+                "session_status": lie_transition_payload["session"]["status"],
+                "answers": [answer["text"] for answer in answers],
+            }
+        )
 
-        finish_res = host_client.post(f"/lobby/sessions/{code}/finish", content_type="application/json")
-        if finish_res.status_code != 200:
-            raise CommandError(f"finish_game failed: {finish_res.status_code}")
+        answer_texts = {answer["text"] for answer in answers}
+        correct_answer = next((answer["text"] for answer in answers if answer.get("text") == question.correct_answer), None)
+        if correct_answer is None:
+            self._fail("submit_guesses", "could not resolve correct answer from mixed answers", {"answers": answers})
+
+        guess_plan = {
+            players[0]["nickname"]: "Lie from P2",
+            players[1]["nickname"]: correct_answer,
+            players[2]["nickname"]: "Lie from P1",
+        }
+        missing_guess_targets = {text for text in guess_plan.values() if text not in answer_texts}
+        if missing_guess_targets:
+            self._fail(
+                "submit_guesses",
+                "expected bluff targets missing from mixed answers",
+                {"answers": answers, "missing_guess_targets": sorted(missing_guess_targets)},
+            )
+        artifact["guess_plan"] = guess_plan
+
+        guess_payloads = []
+        for player in players:
+            nickname = player["nickname"]
+            guess_payload = self._expect_status(
+                Client().post(
+                    f"/lobby/sessions/{code}/questions/{round_question_id}/guesses/submit",
+                    data=json.dumps(
+                        {
+                            "player_id": player["id"],
+                            "session_token": player["session_token"],
+                            "selected_text": guess_plan[nickname],
+                        }
+                    ),
+                    content_type="application/json",
+                ),
+                201,
+                f"submit_guess[{nickname}]",
+            )
+            guess_payloads.append(guess_payload)
+
+        reveal_payload = guess_payloads[-1]
+        self._expect_session_status(reveal_payload, GameSession.Status.REVEAL, "auto_reveal_transition")
+        if not reveal_payload.get("phase_transition", {}).get("auto_advanced"):
+            self._fail("auto_reveal_transition", "expected auto_advanced=true on final guess", reveal_payload)
+        reveal = reveal_payload.get("reveal")
+        if not reveal:
+            self._fail("auto_reveal_transition", "missing canonical reveal payload", reveal_payload)
+        if reveal.get("correct_answer") != question.correct_answer:
+            self._fail(
+                "auto_reveal_transition",
+                "reveal payload returned wrong correct answer",
+                {"expected": question.correct_answer, "reveal": reveal},
+            )
+        if len(reveal.get("lies", [])) != len(players):
+            self._fail("auto_reveal_transition", "unexpected lie count in reveal payload", reveal)
+        if len(reveal.get("guesses", [])) != len(players):
+            self._fail("auto_reveal_transition", "unexpected guess count in reveal payload", reveal)
+
+        fooled_guesses = [guess for guess in reveal["guesses"] if not guess.get("is_correct")]
+        correct_guesses = [guess for guess in reveal["guesses"] if guess.get("is_correct")]
+        if len(fooled_guesses) != 2:
+            self._fail("auto_reveal_transition", "expected exactly two bluff guesses", reveal)
+        if len(correct_guesses) != 1:
+            self._fail("auto_reveal_transition", "expected exactly one correct guess", reveal)
+        if any(guess.get("fooled_player_id") is None for guess in fooled_guesses):
+            self._fail("auto_reveal_transition", "bluff guesses missing fooled_player_id", reveal)
+
+        artifact["steps"].append(
+            {
+                "step": "submit_guesses",
+                "guess_results": [
+                    {
+                        "player_id": payload["guess"]["player_id"],
+                        "selected_text": payload["guess"]["selected_text"],
+                        "is_correct": payload["guess"]["is_correct"],
+                        "fooled_player_id": payload["guess"].get("fooled_player_id"),
+                    }
+                    for payload in guess_payloads
+                ],
+            }
+        )
+        artifact["steps"].append(
+            {
+                "step": "auto_reveal_transition",
+                "session_status": reveal_payload["session"]["status"],
+                "reveal": {
+                    "correct_answer": reveal["correct_answer"],
+                    "lies_count": len(reveal["lies"]),
+                    "guesses_count": len(reveal["guesses"]),
+                    "fooled_player_ids": sorted(guess["fooled_player_id"] for guess in fooled_guesses),
+                    "correct_guess_player_ids": sorted(guess["player_id"] for guess in correct_guesses),
+                },
+            }
+        )
+
+        detail_payload = self._expect_status(host_client.get(f"/lobby/sessions/{code}"), 200, "session_detail_after_guesses")
+        self._expect_session_status(detail_payload, GameSession.Status.SCOREBOARD, "auto_scoreboard_transition")
+        if detail_payload.get("reveal") != reveal:
+            self._fail("auto_scoreboard_transition", "scoreboard promotion changed canonical reveal payload", detail_payload)
+        scoreboard = detail_payload.get("scoreboard")
+        if not scoreboard:
+            self._fail("auto_scoreboard_transition", "missing scoreboard payload after promotion", detail_payload)
+        if len(scoreboard) != len(players):
+            self._fail("auto_scoreboard_transition", "unexpected scoreboard length", detail_payload)
+        if not detail_payload.get("phase_view_model", {}).get("readiness", {}).get("scoreboard_ready"):
+            self._fail("auto_scoreboard_transition", "scoreboard_ready=false after promotion", detail_payload)
+
+        artifact["steps"].append(
+            {
+                "step": "auto_scoreboard_transition",
+                "session_status": detail_payload["session"]["status"],
+                "leaderboard": scoreboard,
+            }
+        )
+
+        finish_payload = self._expect_status(
+            host_client.post(f"/lobby/sessions/{code}/finish", content_type="application/json"),
+            200,
+            "finish_game",
+        )
+        self._expect_session_status(finish_payload, GameSession.Status.FINISHED, "finish_game")
+        artifact["steps"].append(
+            {
+                "step": "finish_game",
+                "session_status": finish_payload["session"]["status"],
+            }
+        )
 
         artifact_path = options.get("artifact")
         if artifact_path:
-            artifact = {
-                "ok": True,
-                "command": "smoke_staging",
-                "generated_at": datetime.now(timezone.utc).isoformat(),
-                "session_code": code,
-                "players": [player["nickname"] for player in players],
-                "round_question_id": round_question_id,
-                "steps": [
-                    "create_session",
-                    "join_players",
-                    "start_round",
-                    "submit_lies",
-                    "auto_guess_transition",
-                    "submit_guesses",
-                    "auto_reveal_to_scoreboard",
-                    "finish_game",
-                ],
-            }
             output_path = Path(artifact_path)
             output_path.parent.mkdir(parents=True, exist_ok=True)
             output_path.write_text(json.dumps(artifact, indent=2) + "\n", encoding="utf-8")

lobby/tests.py

@@ -1,3 +1,4 @@
+import inspect
 import json
 import tempfile
 from datetime import timedelta
@@ -10,6 +11,7 @@ from django.test import TestCase, override_settings
 from django.urls import reverse
 from django.utils import timezone
 
+from fupogfakta import payloads as gameplay_payloads, services as gameplay_services
 from fupogfakta.models import (
     Category,
     GameSession,
@@ -21,11 +23,343 @@ from fupogfakta.models import (
     RoundQuestion,
     ScoreEvent,
 )
+from lobby import views as lobby_views
 from lobby.i18n import i18n_locale_config, lobby_i18n_catalog, resolve_error_message, resolve_locale
 
 User = get_user_model()
 
 
+class LobbyGameplayExtractionTests(TestCase):
+    def setUp(self):
+        self.host = User.objects.create_user(username="extract_host", password="secret123")
+        self.client.login(username="extract_host", password="secret123")
+        self.session = GameSession.objects.create(
+            host=self.host,
+            code="EXTR42",
+            status=GameSession.Status.SCOREBOARD,
+        )
+        self.category = Category.objects.create(name="Historie", slug="historie-extract", is_active=True)
+        self.round_config = RoundConfig.objects.create(
+            session=self.session,
+            number=1,
+            category=self.category,
+        )
+        self.question = Question.objects.create(
+            category=self.category,
+            prompt="Hvornår faldt muren?",
+            correct_answer="1989",
+            is_active=True,
+        )
+
+    def test_lobby_views_use_extracted_gameplay_helpers(self):
+        self.assertIs(lobby_views._get_current_round_question, gameplay_services.get_current_round_question)
+        self.assertIs(lobby_views._select_round_question, gameplay_services.select_round_question)
+        self.assertIs(lobby_views._prepare_mixed_answers, gameplay_services.prepare_mixed_answers)
+        self.assertIs(lobby_views._resolve_scores, gameplay_services.resolve_scores)
+        self.assertIs(lobby_views._promote_reveal_to_scoreboard, gameplay_services.promote_reveal_to_scoreboard)
+        self.assertIs(lobby_views._start_round, gameplay_services.start_round)
+        self.assertIs(lobby_views._show_question, gameplay_services.show_question)
+        self.assertIs(lobby_views._start_next_round, gameplay_services.start_next_round)
+        self.assertIs(lobby_views._finish_game, gameplay_services.finish_game)
+        self.assertIs(lobby_views._build_session_detail_gameplay_payload, gameplay_payloads.build_session_detail_gameplay_payload)
+        self.assertIs(lobby_views._build_scoreboard_phase_event, gameplay_payloads.build_scoreboard_phase_event)
+
+    def test_start_round_view_source_stays_http_thin(self):
+        source = inspect.getsource(inspect.unwrap(lobby_views.start_round))
+
+        self.assertIn("transition = _start_round(session, category_slug)", source)
+        self.assertNotIn("RoundConfig", source)
+        self.assertNotIn("RoundQuestion", source)
+        self.assertNotIn("build_start_round_response", source)
+
+    def test_show_question_view_source_stays_http_thin(self):
+        source = inspect.getsource(inspect.unwrap(lobby_views.show_question))
+
+        self.assertIn("transition = _show_question(session)", source)
+        self.assertNotIn("RoundConfig", source)
+        self.assertNotIn("RoundQuestion", source)
+        self.assertNotIn("build_question_shown_response", source)
+
+    def test_start_next_round_view_source_stays_http_thin(self):
+        source = inspect.getsource(inspect.unwrap(lobby_views.start_next_round))
+
+        self.assertIn("transition = _start_next_round(session)", source)
+        self.assertNotIn("RoundConfig", source)
+        self.assertNotIn("RoundQuestion", source)
+        self.assertNotIn("build_start_next_round_response", source)
+        self.assertNotIn("build_start_next_round_phase_event", source)
+
+    def test_finish_game_view_source_stays_http_thin(self):
+        source = inspect.getsource(inspect.unwrap(lobby_views.finish_game))
+
+        self.assertIn("transition = _finish_game(session)", source)
+        self.assertNotIn("RoundConfig", source)
+        self.assertNotIn("RoundQuestion", source)
+        self.assertNotIn("build_finish_game_response", source)
+        self.assertNotIn("build_finish_game_phase_event", source)
+
+    def test_reveal_scoreboard_view_source_stays_http_thin(self):
+        source = inspect.getsource(inspect.unwrap(lobby_views.reveal_scoreboard))
+
+        self.assertIn("transition = _promote_reveal_to_scoreboard(session)", source)
+        self.assertNotIn("Player.objects.filter(session=session)", source)
+        self.assertNotIn("ScoreEvent.objects.filter", source)
+        self.assertNotIn("build_reveal_scoreboard_response", source)
+        self.assertNotIn("build_scoreboard_phase_event", source)
+
+    def test_issue_310_transition_views_keep_gameplay_logic_out_of_lobby(self):
+        transition_sources = {
+            "reveal_scoreboard": inspect.getsource(inspect.unwrap(lobby_views.reveal_scoreboard)),
+            "start_next_round": inspect.getsource(inspect.unwrap(lobby_views.start_next_round)),
+            "finish_game": inspect.getsource(inspect.unwrap(lobby_views.finish_game)),
+        }
+
+        forbidden_snippets = (
+            "RoundConfig.objects.get_or_create(",
+            "RoundConfig.objects.create(",
+            "RoundQuestion.objects.create(",
+            "select_round_question(",
+            "reset_round_question_bootstrap_state(",
+            "session.current_round =",
+            "session.status = GameSession.Status.LIE",
+            "session.status = GameSession.Status.SCOREBOARD",
+            "session.status = GameSession.Status.FINISHED",
+            "build_start_next_round_response(",
+            "build_start_next_round_phase_event(",
+            "build_finish_game_response(",
+            "build_finish_game_phase_event(",
+            "build_reveal_scoreboard_response(",
+            "build_scoreboard_phase_event(",
+            "ScoreEvent.objects.filter(",
+            "Player.objects.filter(",
+        )
+
+        for view_name, source in transition_sources.items():
+            for snippet in forbidden_snippets:
+                self.assertNotIn(snippet, source, msg=f"{view_name} leaked gameplay snippet: {snippet}")
+
+    def test_session_detail_view_source_stays_http_thin(self):
+        source = inspect.getsource(inspect.unwrap(lobby_views.session_detail))
+
+        self.assertIn("session = _maybe_promote_reveal_to_scoreboard(session)", source)
+        self.assertIn("current_round_question = _get_current_round_question(session)", source)
+        self.assertIn("gameplay_payload = _build_session_detail_gameplay_payload(", source)
+        self.assertIn("**gameplay_payload", source)
+        self.assertNotIn("build_round_question_payload", source)
+        self.assertNotIn("build_phase_view_model", source)
+        self.assertNotIn("build_reveal_payload", source)
+        self.assertNotIn("build_scoreboard_phase_event(session)[\"payload\"][\"leaderboard\"]", source)
+        self.assertNotIn("lies.select_related", source)
+        self.assertNotIn("guesses.select_related", source)
+        self.assertNotIn("Player.objects.filter(session=session)", source)
+        self.assertNotIn("leaderboard =", source)
+
+
+    @patch("lobby.views.sync_broadcast_phase_event")
+    @patch("lobby.views._start_round")
+    def test_start_round_view_delegates_transition_to_service(
+        self,
+        mock_start_round,
+        mock_sync_broadcast_phase_event,
+    ):
+        lobby_session = GameSession.objects.create(host=self.host, code="LOBBY1", status=GameSession.Status.LOBBY)
+        transition = gameplay_services.RoundTransitionResult(
+            session=lobby_session,
+            round_config=self.round_config,
+            round_question=RoundQuestion.objects.create(
+                session=lobby_session,
+                round_number=1,
+                question=self.question,
+                correct_answer=self.question.correct_answer,
+            ),
+            should_broadcast=True,
+            response_payload={"ok": True},
+            phase_event_name="phase.lie_started",
+            phase_event_payload={"round_question_id": 123},
+        )
+        mock_start_round.return_value = transition
+
+        response = self.client.post(
+            reverse("lobby:start_round", kwargs={"code": lobby_session.code}),
+            data=json.dumps({"category_slug": self.category.slug}),
+            content_type="application/json",
+        )
+
+        self.assertEqual(response.status_code, 201)
+        self.assertEqual(response.json(), {"ok": True})
+        mock_start_round.assert_called_once_with(lobby_session, self.category.slug)
+        mock_sync_broadcast_phase_event.assert_called_once_with(
+            lobby_session.code,
+            "phase.lie_started",
+            {"round_question_id": 123},
+        )
+
+    @patch("lobby.views.sync_broadcast_phase_event")
+    @patch("lobby.views._show_question")
+    def test_show_question_view_delegates_transition_to_service(
+        self,
+        mock_show_question,
+        mock_sync_broadcast_phase_event,
+    ):
+        lie_session = GameSession.objects.create(host=self.host, code="LIE123", status=GameSession.Status.LIE)
+        transition = gameplay_services.RoundTransitionResult(
+            session=lie_session,
+            round_config=self.round_config,
+            round_question=RoundQuestion.objects.create(
+                session=lie_session,
+                round_number=1,
+                question=self.question,
+                correct_answer=self.question.correct_answer,
+            ),
+            should_broadcast=True,
+            response_payload={"ok": True},
+            phase_event_name="phase.question_shown",
+            phase_event_payload={"round_question_id": 456},
+        )
+        mock_show_question.return_value = transition
+
+        response = self.client.post(reverse("lobby:show_question", kwargs={"code": lie_session.code}))
+
+        self.assertEqual(response.status_code, 201)
+        self.assertEqual(response.json(), {"ok": True})
+        mock_show_question.assert_called_once_with(lie_session)
+        mock_sync_broadcast_phase_event.assert_called_once_with(
+            lie_session.code,
+            "phase.question_shown",
+            {"round_question_id": 456},
+        )
+
+    @patch("lobby.views.sync_broadcast_phase_event")
+    @patch("lobby.views._start_next_round")
+    def test_start_next_round_view_delegates_transition_to_service(
+        self,
+        mock_start_next_round,
+        mock_sync_broadcast_phase_event,
+    ):
+        next_round_config = RoundConfig.objects.create(
+            session=self.session,
+            number=2,
+            category=self.category,
+            started_from_scoreboard=True,
+        )
+        round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=self.question,
+            correct_answer=self.question.correct_answer,
+        )
+        transition = gameplay_services.RoundTransitionResult(
+            session=self.session,
+            round_config=next_round_config,
+            round_question=round_question,
+            should_broadcast=True,
+            response_payload={"ok": True},
+            phase_event_name="phase.lie_started",
+            phase_event_payload={"round_question_id": round_question.id},
+        )
+        mock_start_next_round.return_value = transition
+
+        response = self.client.post(reverse("lobby:start_next_round", kwargs={"code": self.session.code}))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json(), {"ok": True})
+        mock_start_next_round.assert_called_once_with(self.session)
+        mock_sync_broadcast_phase_event.assert_called_once_with(
+            self.session.code,
+            "phase.lie_started",
+            {"round_question_id": round_question.id},
+        )
+
+    @patch("lobby.views.sync_broadcast_phase_event")
+    @patch("lobby.views._finish_game")
+    def test_finish_game_view_delegates_transition_to_service(
+        self,
+        mock_finish_game,
+        mock_sync_broadcast_phase_event,
+    ):
+        finished_session = GameSession.objects.get(pk=self.session.pk)
+        finished_session.status = GameSession.Status.FINISHED
+        transition = gameplay_services.FinishGameResult(
+            session=finished_session,
+            should_broadcast=True,
+            response_payload={"ok": True},
+            phase_event_name="phase.game_over",
+            phase_event_payload={"winner": None, "leaderboard": []},
+        )
+        mock_finish_game.return_value = transition
+
+        response = self.client.post(reverse("lobby:finish_game", kwargs={"code": self.session.code}))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json(), {"ok": True})
+        mock_finish_game.assert_called_once_with(self.session)
+        mock_sync_broadcast_phase_event.assert_called_once_with(
+            self.session.code,
+            "phase.game_over",
+            {"winner": None, "leaderboard": []},
+        )
+
+    @patch("lobby.views.sync_broadcast_phase_event")
+    @patch("lobby.views._start_next_round")
+    def test_start_next_round_view_skips_broadcast_on_service_replay(
+        self,
+        mock_start_next_round,
+        mock_sync_broadcast_phase_event,
+    ):
+        replay_round_config = RoundConfig.objects.create(
+            session=self.session,
+            number=2,
+            category=self.category,
+            started_from_scoreboard=True,
+        )
+        round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=self.question,
+            correct_answer=self.question.correct_answer,
+        )
+        replay_session = GameSession.objects.get(pk=self.session.pk)
+        replay_session.status = GameSession.Status.LIE
+        replay_session.current_round = 2
+        transition = gameplay_services.RoundTransitionResult(
+            session=replay_session,
+            round_config=replay_round_config,
+            round_question=round_question,
+            should_broadcast=False,
+            response_payload={"ok": True},
+        )
+        mock_start_next_round.return_value = transition
+
+        response = self.client.post(reverse("lobby:start_next_round", kwargs={"code": self.session.code}))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json(), {"ok": True})
+        mock_start_next_round.assert_called_once_with(self.session)
+        mock_sync_broadcast_phase_event.assert_not_called()
+
+    @patch("lobby.views.sync_broadcast_phase_event")
+    @patch("lobby.views._finish_game")
+    def test_finish_game_view_skips_broadcast_on_service_replay(
+        self,
+        mock_finish_game,
+        mock_sync_broadcast_phase_event,
+    ):
+        finished_session = GameSession.objects.get(pk=self.session.pk)
+        finished_session.status = GameSession.Status.FINISHED
+        transition = gameplay_services.FinishGameResult(
+            session=finished_session,
+            should_broadcast=False,
+            response_payload={"ok": True},
+        )
+        mock_finish_game.return_value = transition
+
+        response = self.client.post(reverse("lobby:finish_game", kwargs={"code": self.session.code}))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json(), {"ok": True})
+        mock_finish_game.assert_called_once_with(self.session)
+        mock_sync_broadcast_phase_event.assert_not_called()
+
 class LobbyFlowTests(TestCase):
     def setUp(self):
         self.host = User.objects.create_user(username="host", password="secret123")
@@ -308,7 +642,7 @@ class StartRoundTests(TestCase):
         self.assertEqual(response.json()["locale"], "en")
         self.assertEqual(response.json()["error"], "Only host can start round")
 
-    @patch("lobby.views._select_round_question", side_effect=ValueError("no_available_questions"))
+    @patch("fupogfakta.services.select_round_question", side_effect=ValueError("no_available_questions"))
     def test_start_round_does_not_persist_round_config_when_question_selection_fails(self, _mock_select_round_question):
         self.client.login(username="host", password="secret123")
 
@@ -867,6 +1201,79 @@ class CanonicalRoundFlowTests(TestCase):
             },
         )
 
+    def test_canonical_round_flow_bootstraps_second_round_without_first_round_carry_over(self):
+        self.client.login(username="host_canonical", password="secret123")
+        extra_question = Question.objects.create(
+            category=self.category,
+            prompt="Hvem malede Mona Lisa?",
+            correct_answer="Da Vinci",
+            is_active=True,
+        )
+
+        start_response = self.client.post(
+            reverse("lobby:start_round", kwargs={"code": self.session.code}),
+            data={"category_slug": self.category.slug},
+            content_type="application/json",
+        )
+        self.assertEqual(start_response.status_code, 201)
+        first_round_question_id = start_response.json()["round_question"]["id"]
+        first_round_prompt = start_response.json()["round_question"]["prompt"]
+        first_round_correct_answer = RoundQuestion.objects.get(pk=first_round_question_id).correct_answer
+        second_question = extra_question if first_round_prompt == self.question.prompt else self.question
+
+        final_lie_response = None
+        for index, player in enumerate(self.players, start=1):
+            lie_response = self.client.post(
+                reverse("lobby:submit_lie", kwargs={"code": self.session.code, "round_question_id": first_round_question_id}),
+                data={"player_id": player.id, "session_token": player.session_token, "text": f"Første løgn {index}"},
+                content_type="application/json",
+            )
+            self.assertEqual(lie_response.status_code, 201)
+            final_lie_response = lie_response
+
+        self.assertIsNotNone(final_lie_response)
+
+        for player, selected_text in zip(
+            self.players,
+            [first_round_correct_answer, first_round_correct_answer, first_round_correct_answer],
+            strict=True,
+        ):
+            guess_response = self.client.post(
+                reverse("lobby:submit_guess", kwargs={"code": self.session.code, "round_question_id": first_round_question_id}),
+                data={"player_id": player.id, "session_token": player.session_token, "selected_text": selected_text},
+                content_type="application/json",
+            )
+            self.assertEqual(guess_response.status_code, 201)
+
+        scoreboard_payload = self.client.get(reverse("lobby:session_detail", kwargs={"code": self.session.code})).json()
+        self.assertEqual(scoreboard_payload["session"]["status"], GameSession.Status.SCOREBOARD)
+        self.assertEqual(scoreboard_payload["round_question"]["id"], first_round_question_id)
+        self.assertIsNotNone(scoreboard_payload["reveal"])
+        self.assertIsNotNone(scoreboard_payload["scoreboard"])
+        self.assertGreaterEqual(len(scoreboard_payload["reveal"]["guesses"]), 1)
+
+        next_round_response = self.client.post(reverse("lobby:start_next_round", kwargs={"code": self.session.code}))
+        self.assertEqual(next_round_response.status_code, 200)
+        self.assertEqual(next_round_response.json()["session"]["status"], GameSession.Status.LIE)
+        self.assertEqual(next_round_response.json()["session"]["current_round"], 2)
+
+        detail_payload = self.client.get(reverse("lobby:session_detail", kwargs={"code": self.session.code})).json()
+        self.assertEqual(detail_payload["session"]["status"], GameSession.Status.LIE)
+        self.assertEqual(detail_payload["session"]["current_round"], 2)
+        self.assertEqual(detail_payload["phase_view_model"]["current_phase"], GameSession.Status.LIE)
+        self.assertIsNone(detail_payload["reveal"])
+        self.assertIsNone(detail_payload["scoreboard"])
+        self.assertEqual(detail_payload["round_question"]["round_number"], 2)
+        self.assertNotEqual(detail_payload["round_question"]["id"], first_round_question_id)
+        self.assertEqual(detail_payload["round_question"]["prompt"], second_question.prompt)
+        self.assertEqual(detail_payload["round_question"]["answers"], [])
+
+        round_two_question = RoundQuestion.objects.get(session=self.session, round_number=2)
+        self.assertEqual(round_two_question.question, second_question)
+        self.assertEqual(round_two_question.lies.count(), 0)
+        self.assertEqual(round_two_question.guesses.count(), 0)
+        self.assertEqual(round_two_question.mixed_answers, [])
+
     @patch("lobby.views.sync_broadcast_phase_event")
     @patch("lobby.views._resolve_scores")
     @patch("lobby.views.GameSession.objects.get")
@@ -1294,7 +1701,12 @@ class RevealRoundFlowTests(TestCase):
         self.assertEqual(self.session.status, GameSession.Status.LIE)
         self.assertEqual(self.session.current_round, 2)
         self.assertTrue(
-            RoundConfig.objects.filter(session=self.session, number=2, category=self.category).exists()
+            RoundConfig.objects.filter(
+                session=self.session,
+                number=2,
+                category=self.category,
+                started_from_scoreboard=True,
+            ).exists()
         )
         self.assertTrue(
             RoundQuestion.objects.filter(session=self.session, round_number=2, question=self.next_question).exists()
@@ -1303,6 +1715,47 @@ class RevealRoundFlowTests(TestCase):
         self.assertEqual(mock_sync_broadcast_phase_event.call_args.args[0], self.session.code)
         self.assertEqual(mock_sync_broadcast_phase_event.call_args.args[1], "phase.lie_started")
 
+    @patch("lobby.views.sync_broadcast_phase_event")
+    def test_start_next_round_bootstraps_new_round_question_instead_of_reusing_current_round(self, mock_sync_broadcast_phase_event):
+        self.client.login(username="host_reveal", password="secret123")
+        self.client.get(reverse("lobby:reveal_scoreboard", kwargs={"code": self.session.code}))
+        mock_sync_broadcast_phase_event.reset_mock()
+
+        stale_shown_at = timezone.now() - timedelta(minutes=10)
+        current_round_question = RoundQuestion.objects.get(session=self.session, round_number=1)
+        current_round_question.shown_at = stale_shown_at
+        current_round_question.mixed_answers = ["Stale truth", "Stale lie"]
+        current_round_question.save(update_fields=["shown_at", "mixed_answers"])
+        LieAnswer.objects.create(round_question=current_round_question, player=self.player_one, text="Stale lie")
+        Guess.objects.create(
+            round_question=current_round_question,
+            player=self.player_two,
+            selected_text="Stale truth",
+            is_correct=True,
+        )
+
+        response = self.client.post(reverse("lobby:start_next_round", kwargs={"code": self.session.code}))
+
+        self.assertEqual(response.status_code, 200)
+        self.session.refresh_from_db()
+        current_round_question.refresh_from_db()
+        self.assertEqual(self.session.status, GameSession.Status.LIE)
+        self.assertEqual(self.session.current_round, 2)
+        payload = response.json()
+        self.assertEqual(payload["round_question"]["id"], RoundQuestion.objects.get(session=self.session, round_number=2).id)
+        self.assertEqual(payload["round_question"]["prompt"], self.next_question.prompt)
+        self.assertEqual(current_round_question.round_number, 1)
+        self.assertEqual(current_round_question.question_id, self.question.id)
+        self.assertEqual(current_round_question.shown_at, stale_shown_at)
+        self.assertEqual(current_round_question.mixed_answers, ["Stale truth", "Stale lie"])
+        self.assertEqual(current_round_question.lies.count(), 1)
+        self.assertEqual(current_round_question.guesses.count(), 1)
+        detail_payload = self.client.get(reverse("lobby:session_detail", kwargs={"code": self.session.code})).json()
+        self.assertEqual(detail_payload["round_question"]["id"], payload["round_question"]["id"])
+        self.assertEqual(detail_payload["round_question"]["prompt"], self.next_question.prompt)
+        mock_sync_broadcast_phase_event.assert_called_once()
+        self.assertEqual(mock_sync_broadcast_phase_event.call_args.args[1], "phase.lie_started")
+
     @patch("lobby.views.sync_broadcast_phase_event")
     def test_start_next_round_is_idempotent_after_transition_to_lie(self, mock_sync_broadcast_phase_event):
         self.client.login(username="host_reveal", password="secret123")
@@ -1326,6 +1779,178 @@ class RevealRoundFlowTests(TestCase):
         mock_sync_broadcast_phase_event.assert_called_once()
         self.assertEqual(mock_sync_broadcast_phase_event.call_args.args[1], "phase.lie_started")
 
+    def test_start_next_round_rejects_plain_lie_phase_without_prior_scoreboard_transition(self):
+        self.client.login(username="host_reveal", password="secret123")
+        ScoreEvent.objects.filter(session=self.session).delete()
+        self.session.status = GameSession.Status.LIE
+        self.session.current_round = 2
+        self.session.save(update_fields=["status", "current_round"])
+        RoundConfig.objects.create(session=self.session, number=2, category=self.category, started_from_scoreboard=False)
+        RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=self.next_question,
+            correct_answer=self.next_question.correct_answer,
+        )
+
+        response = self.client.post(
+            reverse(
+                "lobby:start_next_round",
+                kwargs={"code": self.session.code},
+            ),
+            HTTP_ACCEPT_LANGUAGE="en",
+        )
+
+        self.assertEqual(response.status_code, 400)
+        self.assertEqual(response.json()["error_code"], "next_round_invalid_phase")
+        self.session.refresh_from_db()
+        self.assertEqual(self.session.status, GameSession.Status.LIE)
+        self.assertEqual(self.session.current_round, 2)
+        self.assertEqual(RoundConfig.objects.filter(session=self.session, number=1).count(), 1)
+        self.assertEqual(RoundConfig.objects.filter(session=self.session, number=2).count(), 1)
+        self.assertEqual(RoundQuestion.objects.filter(session=self.session, round_number=1).count(), 1)
+        self.assertEqual(RoundQuestion.objects.filter(session=self.session, round_number=2).count(), 1)
+
+    def test_start_next_round_clears_existing_next_round_bootstrap_state(self):
+        self.client.login(username="host_reveal", password="secret123")
+        self.client.get(reverse("lobby:reveal_scoreboard", kwargs={"code": self.session.code}))
+
+        stale_shown_at = timezone.now() - timedelta(minutes=10)
+        stale_round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=self.next_question,
+            correct_answer=self.next_question.correct_answer,
+            shown_at=stale_shown_at,
+            mixed_answers=["Stale truth", "Stale lie"],
+        )
+        LieAnswer.objects.create(round_question=stale_round_question, player=self.player_one, text="Stale lie")
+        Guess.objects.create(
+            round_question=stale_round_question,
+            player=self.player_two,
+            selected_text="Stale truth",
+            is_correct=True,
+        )
+
+        response = self.client.post(reverse("lobby:start_next_round", kwargs={"code": self.session.code}))
+
+        self.assertEqual(response.status_code, 200)
+        self.session.refresh_from_db()
+        stale_round_question.refresh_from_db()
+        self.assertEqual(self.session.status, GameSession.Status.LIE)
+        self.assertEqual(self.session.current_round, 2)
+        response_payload = response.json()
+        self.assertEqual(response_payload["round_question"]["id"], stale_round_question.id)
+        self.assertEqual(stale_round_question.mixed_answers, [])
+        self.assertEqual(stale_round_question.lies.count(), 0)
+        self.assertEqual(stale_round_question.guesses.count(), 0)
+        self.assertNotEqual(stale_round_question.shown_at, stale_shown_at)
+        self.assertGreater(stale_round_question.shown_at, stale_shown_at)
+        self.assertEqual(response_payload["round_question"]["shown_at"], stale_round_question.shown_at.isoformat())
+        expected_deadline = stale_round_question.shown_at + timedelta(seconds=self.round_config.lie_seconds)
+        self.assertEqual(response_payload["round_question"]["lie_deadline_at"], expected_deadline.isoformat())
+        self.assertGreater(expected_deadline, timezone.now())
+
+        detail_payload = self.client.get(reverse("lobby:session_detail", kwargs={"code": self.session.code})).json()
+        self.assertEqual(detail_payload["session"]["status"], GameSession.Status.LIE)
+
+    def test_start_next_round_reuses_existing_next_round_config_with_refreshed_canonical_values(self):
+        self.client.login(username="host_reveal", password="secret123")
+        self.client.get(reverse("lobby:reveal_scoreboard", kwargs={"code": self.session.code}))
+
+        stale_category = Category.objects.create(name="Sport reveal", slug="sport-reveal", is_active=True)
+        stale_round_config = RoundConfig.objects.create(
+            session=self.session,
+            number=2,
+            category=stale_category,
+            lie_seconds=12,
+            guess_seconds=18,
+            points_correct=9,
+            points_bluff=7,
+            started_from_scoreboard=False,
+        )
+        stale_round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=self.next_question,
+            correct_answer=self.next_question.correct_answer,
+            shown_at=timezone.now() - timedelta(minutes=10),
+            mixed_answers=["Stale truth"],
+        )
+
+        response = self.client.post(reverse("lobby:start_next_round", kwargs={"code": self.session.code}))
+
+        self.assertEqual(response.status_code, 200)
+        self.session.refresh_from_db()
+        stale_round_config.refresh_from_db()
+        stale_round_question.refresh_from_db()
+        self.assertEqual(self.session.status, GameSession.Status.LIE)
+        self.assertEqual(self.session.current_round, 2)
+        self.assertEqual(RoundConfig.objects.filter(session=self.session, number=2).count(), 1)
+        self.assertEqual(stale_round_config.category_id, self.round_config.category_id)
+        self.assertEqual(stale_round_config.lie_seconds, self.round_config.lie_seconds)
+        self.assertEqual(stale_round_config.guess_seconds, self.round_config.guess_seconds)
+        self.assertEqual(stale_round_config.points_correct, self.round_config.points_correct)
+        self.assertEqual(stale_round_config.points_bluff, self.round_config.points_bluff)
+        self.assertTrue(stale_round_config.started_from_scoreboard)
+        self.assertEqual(response.json()["round_question"]["id"], stale_round_question.id)
+        self.assertEqual(response.json()["config"]["lie_seconds"], self.round_config.lie_seconds)
+        expected_deadline = stale_round_question.shown_at + timedelta(seconds=self.round_config.lie_seconds)
+        self.assertEqual(response.json()["round_question"]["lie_deadline_at"], expected_deadline.isoformat())
+        detail_payload = self.client.get(reverse("lobby:session_detail", kwargs={"code": self.session.code})).json()
+        self.assertEqual(detail_payload["session"]["current_round"], 2)
+        self.assertEqual(detail_payload["round_question"]["id"], stale_round_question.id)
+        self.assertEqual(detail_payload["round_question"]["answers"], [])
+        self.assertIsNone(detail_payload["reveal"])
+        self.assertIsNone(detail_payload["scoreboard"])
+
+    def test_start_next_round_repairs_reused_bootstrap_question_with_drifted_category(self):
+        self.client.login(username="host_reveal", password="secret123")
+        self.client.get(reverse("lobby:reveal_scoreboard", kwargs={"code": self.session.code}))
+
+        stale_category = Category.objects.create(name="Drift reveal", slug="drift-reveal", is_active=True)
+        stale_question = Question.objects.create(
+            category=stale_category,
+            prompt="Hvem vandt EM i 1992?",
+            correct_answer="Danmark",
+            is_active=True,
+        )
+        stale_round_question = RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=stale_question,
+            correct_answer=stale_question.correct_answer,
+            shown_at=timezone.now() - timedelta(minutes=10),
+            mixed_answers=["Stale truth", "Stale lie"],
+        )
+        LieAnswer.objects.create(round_question=stale_round_question, player=self.player_one, text="Tyskland")
+        Guess.objects.create(
+            round_question=stale_round_question,
+            player=self.player_two,
+            selected_text="Stale truth",
+            is_correct=True,
+        )
+
+        response = self.client.post(reverse("lobby:start_next_round", kwargs={"code": self.session.code}))
+
+        self.assertEqual(response.status_code, 200)
+        self.session.refresh_from_db()
+        stale_round_question.refresh_from_db()
+        self.assertEqual(self.session.status, GameSession.Status.LIE)
+        self.assertEqual(self.session.current_round, 2)
+        self.assertEqual(stale_round_question.question.category_id, self.round_config.category_id)
+        self.assertEqual(stale_round_question.question_id, self.next_question.id)
+        self.assertEqual(stale_round_question.correct_answer, self.next_question.correct_answer)
+        self.assertEqual(stale_round_question.mixed_answers, [])
+        self.assertEqual(stale_round_question.lies.count(), 0)
+        self.assertEqual(stale_round_question.guesses.count(), 0)
+        payload = response.json()
+        self.assertEqual(payload["round_question"]["id"], stale_round_question.id)
+        self.assertEqual(payload["round_question"]["prompt"], self.next_question.prompt)
+        detail_payload = self.client.get(reverse("lobby:session_detail", kwargs={"code": self.session.code})).json()
+        self.assertEqual(detail_payload["round_question"]["id"], stale_round_question.id)
+        self.assertEqual(detail_payload["round_question"]["prompt"], self.next_question.prompt)
+
     def test_start_next_round_requires_host(self):
         self.session.status = GameSession.Status.SCOREBOARD
         self.session.save(update_fields=["status"])
@@ -1947,7 +2572,7 @@ class SmokeStagingCommandTests(TestCase):
         self.assertEqual(session.status, GameSession.Status.FINISHED)
         self.assertEqual(Player.objects.filter(session=session).count(), 3)
 
-    def test_smoke_staging_writes_artifact_when_requested(self):
+    def test_smoke_staging_writes_phase_evidence_artifact_when_requested(self):
         with tempfile.TemporaryDirectory() as tmp_dir:
             artifact_path = Path(tmp_dir) / "smoke.json"
             call_command("smoke_staging", artifact=str(artifact_path))
@@ -1955,24 +2580,40 @@ class SmokeStagingCommandTests(TestCase):
             self.assertTrue(artifact_path.exists())
             payload = json.loads(artifact_path.read_text(encoding="utf-8"))
             self.assertTrue(payload["ok"])
-            self.assertEqual(payload["command"], "smoke_staging")
+            self.assertEqual(payload["command"], "python manage.py smoke_staging --artifact <path>")
             self.assertEqual(payload["players"], ["P1", "P2", "P3"])
             self.assertIn("generated_at", payload)
             self.assertIn("session_code", payload)
+            self.assertEqual(payload["question"]["correct_answer"], "Correct")
+            self.assertEqual(payload["guess_plan"]["P2"], "Correct")
+
+            step_names = [step["step"] for step in payload["steps"]]
             self.assertEqual(
-                payload["steps"],
+                step_names,
                 [
                     "create_session",
                     "join_players",
                     "start_round",
-                    "submit_lies",
                     "auto_guess_transition",
                     "submit_guesses",
-                    "auto_reveal_to_scoreboard",
+                    "auto_reveal_transition",
+                    "auto_scoreboard_transition",
                     "finish_game",
                 ],
             )
 
+            reveal_step = payload["steps"][5]
+            self.assertEqual(reveal_step["session_status"], GameSession.Status.REVEAL)
+            self.assertEqual(reveal_step["reveal"]["correct_answer"], "Correct")
+            self.assertEqual(reveal_step["reveal"]["lies_count"], 3)
+            self.assertEqual(reveal_step["reveal"]["guesses_count"], 3)
+            self.assertEqual(len(reveal_step["reveal"]["fooled_player_ids"]), 2)
+            self.assertEqual(len(reveal_step["reveal"]["correct_guess_player_ids"]), 1)
+
+            scoreboard_step = payload["steps"][6]
+            self.assertEqual(scoreboard_step["session_status"], GameSession.Status.SCOREBOARD)
+            self.assertEqual(len(scoreboard_step["leaderboard"]), 3)
+
 
 class I18nResolverTests(TestCase):
     def test_resolve_locale_accepts_language_tags_and_normalizes_to_supported_base_locale(self):

lobby/views.py

@@ -1,29 +1,39 @@
-import json
-import random
 from datetime import timedelta
 
+import json
+import random
 from django.contrib.auth.decorators import login_required
 from django.db import IntegrityError, transaction
 from django.http import HttpRequest, JsonResponse
 from django.utils import timezone
 from django.views.decorators.http import require_GET, require_POST
 
-from fupogfakta.models import Category, GameSession, Guess, LieAnswer, Player, Question, RoundConfig, RoundQuestion, ScoreEvent
+from fupogfakta.models import GameSession, Guess, LieAnswer, Player, RoundConfig, RoundQuestion, ScoreEvent
 from fupogfakta.payloads import (
     build_leaderboard as _build_leaderboard,
-    build_lie_started_payload as _build_lie_started_payload,
     build_reveal_payload as _build_reveal_payload,
+    build_scoreboard_phase_event as _build_scoreboard_phase_event,
+    build_session_detail_gameplay_payload as _build_session_detail_gameplay_payload,
 )
 from fupogfakta.services import (
+    finish_game as _finish_game,
     get_current_round_question as _get_current_round_question,
     prepare_mixed_answers as _prepare_mixed_answers,
+    promote_reveal_to_scoreboard as _promote_reveal_to_scoreboard,
     resolve_scores as _resolve_scores,
     select_round_question as _select_round_question,
+    show_question as _show_question,
+    start_next_round as _start_next_round,
+    start_round as _start_round,
 )
 from realtime.broadcast import sync_broadcast_phase_event
-
 from .i18n import api_error
 
+_GAMEPLAY_SERVICE_OWNERSHIP_EXPORTS = (
+    _select_round_question,
+    _build_scoreboard_phase_event,
+)
+
 SESSION_CODE_ALPHABET = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789"
 SESSION_CODE_LENGTH = 6
 MAX_CODE_GENERATION_ATTEMPTS = 20
@@ -65,136 +75,17 @@ def _create_unique_session_code() -> str:
     raise RuntimeError("Could not generate unique session code")
 
 
-def _build_start_next_round_response(
-    session: GameSession,
-    round_config: RoundConfig,
-    round_question: RoundQuestion,
-) -> JsonResponse:
-    lie_started_payload = _build_lie_started_payload(session, round_config, round_question)
-    return JsonResponse(
-        {
-            "session": {
-                "code": session.code,
-                "status": session.status,
-                "current_round": session.current_round,
-            },
-            "round": {
-                "number": round_config.number,
-                "category": {
-                    "slug": round_config.category.slug,
-                    "name": round_config.category.name,
-                },
-            },
-            "round_question": {
-                "id": round_question.id,
-                "prompt": round_question.question.prompt,
-                "round_number": round_question.round_number,
-                "shown_at": round_question.shown_at.isoformat(),
-                "lie_deadline_at": lie_started_payload["lie_deadline_at"],
-            },
-            "config": {
-                "lie_seconds": round_config.lie_seconds,
-            },
-        }
-    )
-
-
-
-def _build_finish_game_response(session: GameSession) -> JsonResponse:
-    leaderboard = _build_leaderboard(session)
-    winner = leaderboard[0] if leaderboard else None
-    return JsonResponse(
-        {
-            "session": {
-                "code": session.code,
-                "status": GameSession.Status.FINISHED,
-                "current_round": session.current_round,
-            },
-            "winner": winner,
-            "leaderboard": leaderboard,
-        }
-    )
-
 
 def _maybe_promote_reveal_to_scoreboard(session: GameSession) -> GameSession:
-    if session.status != GameSession.Status.REVEAL:
-        return session
+    transition = _promote_reveal_to_scoreboard(session)
+    if transition.should_broadcast:
+        sync_broadcast_phase_event(
+            transition.session.code,
+            transition.phase_event_name,
+            transition.phase_event_payload,
+        )
+    return transition.session
 
-    current_round_question = _get_current_round_question(session)
-    if current_round_question is None:
-        return session
-
-    players_count = Player.objects.filter(session=session).count()
-    guess_count = Guess.objects.filter(round_question=current_round_question).count()
-    has_score_events = ScoreEvent.objects.filter(
-        session=session,
-        meta__round_question_id=current_round_question.id,
-    ).exists()
-    reveal_is_resolved = has_score_events or (players_count > 0 and guess_count >= players_count)
-    if not reveal_is_resolved:
-        return session
-
-    with transaction.atomic():
-        locked_session = GameSession.objects.select_for_update().get(pk=session.pk)
-        if locked_session.status != GameSession.Status.REVEAL:
-            return locked_session
-        locked_session.status = GameSession.Status.SCOREBOARD
-        locked_session.save(update_fields=["status"])
-
-    leaderboard = _build_leaderboard(session)
-    sync_broadcast_phase_event(
-        session.code,
-        "phase.scoreboard",
-        {"leaderboard": list(leaderboard), "current_round": session.current_round},
-    )
-    session.refresh_from_db(fields=["status"])
-    return session
-
-
-
-def _build_phase_view_model(session: GameSession, *, players_count: int, has_round_question: bool) -> dict:
-    status = session.status
-    in_lobby = status == GameSession.Status.LOBBY
-    in_lie = status == GameSession.Status.LIE
-    in_guess = status == GameSession.Status.GUESS
-    in_scoreboard = status == GameSession.Status.SCOREBOARD
-    in_finished = status == GameSession.Status.FINISHED
-
-    min_players_reached = players_count >= 3
-    max_players_allowed = players_count <= 5
-
-    return {
-        "status": status,
-        "current_phase": status,
-        "round_number": session.current_round,
-        "players_count": players_count,
-        "constraints": {
-            "min_players_to_start": 3,
-            "max_players_mvp": 5,
-            "min_players_reached": min_players_reached,
-            "max_players_allowed": max_players_allowed,
-        },
-        "readiness": {
-            "question_ready": has_round_question,
-            "scoreboard_ready": status in {GameSession.Status.REVEAL, GameSession.Status.SCOREBOARD, GameSession.Status.FINISHED},
-            "can_advance_to_next_round": in_scoreboard,
-        },
-        "host": {
-            "can_start_round": in_lobby and min_players_reached and max_players_allowed,
-            "can_show_question": False,
-            "can_mix_answers": False,
-            "can_calculate_scores": False,
-            "can_reveal_scoreboard": False,
-            "can_start_next_round": in_scoreboard,
-            "can_finish_game": in_scoreboard,
-        },
-        "player": {
-            "can_join": status in JOINABLE_STATUSES,
-            "can_submit_lie": in_lie and has_round_question,
-            "can_submit_guess": in_guess and has_round_question,
-            "can_view_final_result": in_finished,
-        },
-    }
 
 
 @require_POST
@@ -303,21 +194,10 @@ def session_detail(request: HttpRequest, code: str) -> JsonResponse:
 
     session = _maybe_promote_reveal_to_scoreboard(session)
     current_round_question = _get_current_round_question(session)
-
-    round_question_payload = None
-    if current_round_question:
-        round_question_payload = {
-            "id": current_round_question.id,
-            "round_number": current_round_question.round_number,
-            "prompt": current_round_question.question.prompt,
-            "shown_at": current_round_question.shown_at.isoformat(),
-            "answers": [{"text": text} for text in (current_round_question.mixed_answers or [])],
-        }
-
-    phase_view_model = _build_phase_view_model(
+    gameplay_payload = _build_session_detail_gameplay_payload(
         session,
+        current_round_question=current_round_question,
         players_count=len(players),
-        has_round_question=bool(current_round_question),
     )
 
     return JsonResponse(
@@ -330,14 +210,7 @@ def session_detail(request: HttpRequest, code: str) -> JsonResponse:
                 "players_count": len(players),
             },
             "players": players,
-            "round_question": round_question_payload,
-            "reveal": _build_reveal_payload(current_round_question)
-            if session.status in {GameSession.Status.REVEAL, GameSession.Status.SCOREBOARD} and current_round_question
-            else None,
-            "scoreboard": _build_leaderboard(session)
-            if session.status in {GameSession.Status.SCOREBOARD, GameSession.Status.FINISHED}
-            else None,
-            "phase_view_model": phase_view_model,
+            **gameplay_payload,
         }
     )
 
@@ -373,95 +246,23 @@ def start_round(request: HttpRequest, code: str) -> JsonResponse:
             status=403,
         )
 
-    if session.status != GameSession.Status.LOBBY:
-        return api_error(
-            request,
-            code="round_start_invalid_phase",
-            status=400,
-        )
-
     try:
-        category = Category.objects.get(slug=category_slug, is_active=True)
-    except Category.DoesNotExist:
-        return api_error(
-            request,
-            code="category_not_found",
-            status=404,
-        )
-
-    if not Question.objects.filter(category=category, is_active=True).exists():
-        return api_error(
-            request,
-            code="category_has_no_questions",
-            status=400,
-        )
-
-    with transaction.atomic():
-        session = GameSession.objects.select_for_update().get(pk=session.pk)
-        if session.status != GameSession.Status.LOBBY:
-            return api_error(
-                request,
-                code="round_start_invalid_phase",
-                status=400,
-            )
-
-        if RoundConfig.objects.filter(session=session, number=session.current_round).exists():
-            return api_error(
-                request,
-                code="round_already_configured",
-                status=409,
-            )
-
-        round_config = RoundConfig(
-            session=session,
-            number=session.current_round,
-            category=category,
-        )
-
-        try:
-            round_question = _select_round_question(session, round_config)
-        except ValueError as exc:
-            return api_error(request, code=str(exc), status=400)
-
-        round_config.save()
-        session.status = GameSession.Status.LIE
-        session.save(update_fields=["status"])
-
-    lie_started_payload = _build_lie_started_payload(session, round_config, round_question)
+        transition = _start_round(session, category_slug)
+    except ValueError as exc:
+        error_code = str(exc)
+        error_status = {
+            "category_not_found": 404,
+            "round_already_configured": 409,
+        }.get(error_code, 400)
+        return api_error(request, code=error_code, status=error_status)
 
     sync_broadcast_phase_event(
-        session.code,
-        "phase.lie_started",
-        lie_started_payload,
+        transition.session.code,
+        transition.phase_event_name,
+        transition.phase_event_payload,
     )
 
-    return JsonResponse(
-        {
-            "session": {
-                "code": session.code,
-                "status": session.status,
-                "current_round": session.current_round,
-            },
-            "round": {
-                "number": round_config.number,
-                "category": {
-                    "slug": round_config.category.slug,
-                    "name": round_config.category.name,
-                },
-            },
-            "round_question": {
-                "id": round_question.id,
-                "prompt": round_question.question.prompt,
-                "round_number": round_question.round_number,
-                "shown_at": round_question.shown_at.isoformat(),
-                "lie_deadline_at": lie_started_payload["lie_deadline_at"],
-            },
-            "config": {
-                "lie_seconds": round_config.lie_seconds,
-            },
-        },
-        status=201,
-    )
+    return JsonResponse(transition.response_payload, status=201)
 
 
 @require_POST
@@ -485,60 +286,18 @@ def show_question(request: HttpRequest, code: str) -> JsonResponse:
             status=403,
         )
 
-    if session.status != GameSession.Status.LIE:
-        return api_error(
-            request,
-            code="show_question_invalid_phase",
-            status=400,
-        )
-
     try:
-        round_config = RoundConfig.objects.get(session=session, number=session.current_round)
-    except RoundConfig.DoesNotExist:
-        return api_error(
-            request,
-            code="round_config_missing",
-            status=400,
-        )
-
-    existing_round_question = _get_current_round_question(session)
-    if existing_round_question is not None:
-        round_question = existing_round_question
-    else:
-        try:
-            round_question = _select_round_question(session, round_config)
-        except ValueError as exc:
-            return api_error(request, code=str(exc), status=400)
-
-    lie_deadline_at = round_question.shown_at + timedelta(seconds=round_config.lie_seconds)
+        transition = _show_question(session)
+    except ValueError as exc:
+        return api_error(request, code=str(exc), status=400)
 
     sync_broadcast_phase_event(
-        session.code,
-        "phase.question_shown",
-        {
-            "round_question_id": round_question.id,
-            "prompt": round_question.question.prompt,
-            "shown_at": round_question.shown_at.isoformat(),
-            "lie_deadline_at": lie_deadline_at.isoformat(),
-            "lie_seconds": round_config.lie_seconds,
-        },
+        transition.session.code,
+        transition.phase_event_name,
+        transition.phase_event_payload,
     )
 
-    return JsonResponse(
-        {
-            "round_question": {
-                "id": round_question.id,
-                "prompt": round_question.question.prompt,
-                "round_number": round_question.round_number,
-                "shown_at": round_question.shown_at.isoformat(),
-                "lie_deadline_at": lie_deadline_at.isoformat(),
-            },
-            "config": {
-                "lie_seconds": round_config.lie_seconds,
-            },
-        },
-        status=201,
-    )
+    return JsonResponse(transition.response_payload, status=201)
 
 
 @require_POST
@@ -937,22 +696,18 @@ def reveal_scoreboard(request: HttpRequest, code: str) -> JsonResponse:
     if session.host_id != request.user.id:
         return api_error(request, code="host_only_view_scoreboard", status=403)
 
-    session = _maybe_promote_reveal_to_scoreboard(session)
+    transition = _promote_reveal_to_scoreboard(session)
+    if transition.should_broadcast:
+        sync_broadcast_phase_event(
+            transition.session.code,
+            transition.phase_event_name,
+            transition.phase_event_payload,
+        )
+    session = transition.session
     if session.status not in {GameSession.Status.SCOREBOARD, GameSession.Status.FINISHED}:
         return api_error(request, code="scoreboard_invalid_phase", status=400)
 
-    leaderboard = _build_leaderboard(session)
-
-    return JsonResponse(
-        {
-            "session": {
-                "code": session.code,
-                "status": session.status,
-                "current_round": session.current_round,
-            },
-            "leaderboard": leaderboard,
-        }
-    )
+    return JsonResponse(transition.response_payload)
 
 
 @require_POST
@@ -968,61 +723,19 @@ def start_next_round(request: HttpRequest, code: str) -> JsonResponse:
     if session.host_id != request.user.id:
         return api_error(request, code="host_only_start_next_round", status=403)
 
-    should_broadcast = False
-    with transaction.atomic():
-        locked_session = GameSession.objects.select_for_update().select_related("host").get(pk=session.pk)
-        next_round_config = None
-        round_question = None
+    try:
+        transition = _start_next_round(session)
+    except ValueError as exc:
+        return api_error(request, code=str(exc), status=400)
 
-        if locked_session.status == GameSession.Status.SCOREBOARD:
-            previous_round_config = RoundConfig.objects.filter(
-                session=locked_session,
-                number=locked_session.current_round,
-            ).select_related("category").first()
-            if previous_round_config is None:
-                return api_error(request, code="round_config_missing", status=400)
-
-            next_round_number = locked_session.current_round + 1
-            next_round_config = RoundConfig(
-                session=locked_session,
-                number=next_round_number,
-                category=previous_round_config.category,
-                lie_seconds=previous_round_config.lie_seconds,
-                guess_seconds=previous_round_config.guess_seconds,
-                points_correct=previous_round_config.points_correct,
-                points_bluff=previous_round_config.points_bluff,
-            )
-            locked_session.current_round = next_round_number
-
-            try:
-                round_question = _select_round_question(locked_session, next_round_config)
-            except ValueError as exc:
-                return api_error(request, code=str(exc), status=400)
-
-            next_round_config.save()
-            locked_session.status = GameSession.Status.LIE
-            locked_session.save(update_fields=["current_round", "status"])
-            should_broadcast = True
-        elif locked_session.status == GameSession.Status.LIE:
-            next_round_config = RoundConfig.objects.filter(
-                session=locked_session,
-                number=locked_session.current_round,
-            ).select_related("category").first()
-            round_question = _get_current_round_question(locked_session)
-            if next_round_config is None or round_question is None:
-                return api_error(request, code="next_round_invalid_phase", status=400)
-        else:
-            return api_error(request, code="next_round_invalid_phase", status=400)
-
-    if should_broadcast:
-        lie_started_payload = _build_lie_started_payload(locked_session, next_round_config, round_question)
+    if transition.should_broadcast:
         sync_broadcast_phase_event(
-            locked_session.code,
-            "phase.lie_started",
-            lie_started_payload,
+            transition.session.code,
+            transition.phase_event_name,
+            transition.phase_event_payload,
         )
 
-    return _build_start_next_round_response(locked_session, next_round_config, round_question)
+    return JsonResponse(transition.response_payload)
 
 @require_POST
 @login_required
@@ -1037,26 +750,19 @@ def finish_game(request: HttpRequest, code: str) -> JsonResponse:
     if session.host_id != request.user.id:
         return api_error(request, code="host_only_finish_game", status=403)
 
-    should_broadcast = False
-    with transaction.atomic():
-        locked_session = GameSession.objects.select_for_update().get(pk=session.pk)
-        if locked_session.status == GameSession.Status.SCOREBOARD:
-            locked_session.status = GameSession.Status.FINISHED
-            locked_session.save(update_fields=["status"])
-            should_broadcast = True
-        elif locked_session.status != GameSession.Status.FINISHED:
-            return api_error(request, code="finish_game_invalid_phase", status=400)
+    try:
+        transition = _finish_game(session)
+    except ValueError as exc:
+        return api_error(request, code=str(exc), status=400)
 
-    if should_broadcast:
-        leaderboard = _build_leaderboard(locked_session)
-        winner = leaderboard[0] if leaderboard else None
+    if transition.should_broadcast:
         sync_broadcast_phase_event(
-            locked_session.code,
-            "phase.game_over",
-            {"winner": winner, "leaderboard": list(leaderboard)},
+            transition.session.code,
+            transition.phase_event_name,
+            transition.phase_event_payload,
         )
 
-    return _build_finish_game_response(locked_session)
+    return JsonResponse(transition.response_payload)
 
 
 @require_POST

shared/i18n/artifacts/lobby-mvp-keyspace-parity-report.v1.json

@@ -4,7 +4,7 @@
   "naming_version_rule": "Keep a stable artifact_name and append only explicit schema-major suffixes to the filename/version (v1, v2, ...). Update artifact_version only when the report shape changes; refresh content in-place for catalog/keyspace changes.",
   "source_of_truth": {
     "catalog": "shared/i18n/lobby.json",
-    "catalog_sha256": "e3ed39f2fa25622c01b450bd14fd4da5fc7f96c0d9635bb819f73cae14203beb",
+    "catalog_sha256": "d9f7227bddd007f2c56f33dfd0015bcffb3b60c52dc756126a02b7e4de638adb",
     "source_paths": [
       "lobby/views.py",
       "frontend/src/spa/vertical-slice.ts",
@@ -24,28 +24,7 @@
   },
   "parity": {
     "status": "pass",
-    "django_backend_error_codes_used_by_mvp": [
-      "category_has_no_questions",
-      "category_not_found",
-      "category_slug_required",
-      "host_only_mix_answers",
-      "host_only_show_question",
-      "host_only_start_round",
-      "mix_answers_invalid_phase",
-      "nickname_invalid",
-      "nickname_taken",
-      "no_available_questions",
-      "not_enough_answers_to_mix",
-      "question_already_shown",
-      "round_already_configured",
-      "round_config_missing",
-      "round_question_not_found",
-      "round_start_invalid_phase",
-      "session_code_required",
-      "session_not_found",
-      "session_not_joinable",
-      "show_question_invalid_phase"
-    ],
+    "django_backend_error_codes_used_by_mvp": [],
     "angular_frontend_error_fallback_keys_used_by_mvp": [
       "join_failed",
       "session_code_required",
@@ -158,36 +137,8 @@
       "player.submit_lie",
       "player.title"
     ],
-    "backend_codes_mapped_to_frontend_error_keys": {
-      "category_has_no_questions": "start_round_failed",
-      "category_not_found": "start_round_failed",
-      "category_slug_required": "start_round_failed",
-      "host_only_mix_answers": "start_round_failed",
-      "host_only_show_question": "start_round_failed",
-      "host_only_start_round": "start_round_failed",
-      "mix_answers_invalid_phase": "start_round_failed",
-      "nickname_invalid": "nickname_invalid",
-      "nickname_taken": "nickname_taken",
-      "no_available_questions": "start_round_failed",
-      "not_enough_answers_to_mix": "start_round_failed",
-      "question_already_shown": "start_round_failed",
-      "round_already_configured": "start_round_failed",
-      "round_config_missing": "start_round_failed",
-      "round_question_not_found": "start_round_failed",
-      "round_start_invalid_phase": "start_round_failed",
-      "session_code_required": "session_code_required",
-      "session_not_found": "session_not_found",
-      "session_not_joinable": "join_failed",
-      "show_question_invalid_phase": "start_round_failed"
-    },
-    "unique_frontend_error_keys_reached_from_django": [
-      "join_failed",
-      "nickname_invalid",
-      "nickname_taken",
-      "session_code_required",
-      "session_not_found",
-      "start_round_failed"
-    ],
+    "backend_codes_mapped_to_frontend_error_keys": {},
+    "unique_frontend_error_keys_reached_from_django": [],
     "blocking_issues": {
       "missing_backend_codes": [],
       "missing_backend_translations": [],
@@ -201,11 +152,6 @@
         "priority": "need-to-have",
         "item": "Either add missing backend/error_codes + backend/errors entries for dead contract aliases or remove them from contract.backend_to_frontend_error_keys.",
         "evidence": "host_only_action"
-      },
-      {
-        "priority": "nice-to-have",
-        "item": "Decide whether grouped backend codes should keep collapsing into one Angular fallback key or be split into more specific frontend error copy as UX matures.",
-        "evidence": "start_round_failed <= category_has_no_questions, category_not_found, category_slug_required, host_only_mix_answers, host_only_show_question, host_only_start_round, mix_answers_invalid_phase, no_available_questions, not_enough_answers_to_mix, question_already_shown, round_already_configured, round_config_missing, round_question_not_found, round_start_invalid_phase, show_question_invalid_phase"
       }
     ]
   }