# ============================================================
# 审批文件→DB 存量迁移黄金测试（plan.md §3.3 / 矩阵 112 行剩余项）
# 覆盖：幂等迁移、dry_run 不动库、缺文件空源、后端前置校验、迁移后可读回。
# ============================================================
from __future__ import annotations

import copy
import json
import threading
from pathlib import Path

import pytest
from sqlalchemy import func, select
from sqlalchemy.orm import Session

from server.agent_core.approval_migrate import migrate_file_to_db
from server.agent_core.approval_store import ApprovalStore, token_digest
from server.db.database import get_session, reset_engine
from server.db.models import (
    ApprovalEventRecord,
    ApprovalGrantRecord,
    ApprovalRequestRecord,
)


@pytest.fixture
def database_backend(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
    monkeypatch.setenv("APS_APPROVAL_BACKEND", "database")
    monkeypatch.delenv("APS_APPROVAL_PATH", raising=False)
    monkeypatch.setenv("APS_DATABASE_URL", f"sqlite:///{(tmp_path / 'approval.db').as_posix()}")
    monkeypatch.setenv("APS_APPROVAL_DATABASE_ALLOW_SQLITE", "1")
    reset_engine()
    from server.agent_core import harness
    store = harness.configure_approval_store()
    yield store
    store.clear()
    reset_engine()


def _file_store() -> dict:
    """合成文件后端数据：2 pending + 2 grants + 3 history 事件。"""
    pending = {
        "abc1111111": {
            "confirmId": "abc1111111", "sessionId": "s1", "action": "mes.dispatch",
            "power": "P3", "params": {"versionId": 1}, "paramsHash": "h1",
            "tenantUuid": "platform", "ownerUserId": 1001, "projectId": "p1",
            "worldKey": "w1", "evidenceRefs": ["schedule-version:1"],
            "createdAtEpoch": 1750000000.0, "expiresAtEpoch": 1750003600.0,
        },
        "abc2222222": {
            "confirmId": "abc2222222", "sessionId": "s1", "action": "schedule.publish",
            "power": "P2", "params": {}, "paramsHash": "h2",
            "tenantUuid": "platform", "ownerUserId": 1002, "projectId": "p1",
            "createdAtEpoch": 1750000100.0, "expiresAtEpoch": 1750003700.0,
        },
    }
    grants = {
        "tok1" * 8: {
            "confirmId": "abc1111111", "action": "mes.dispatch", "power": "P3",
            "tenantUuid": "platform", "projectId": "p1", "ownerUserId": 1001,
            "paramsHash": "h1", "status": "ACTIVE",
            "createdAtEpoch": 1750000000.0, "expiresAtEpoch": 1750003600.0,
        },
        "tok2" * 8: {
            "confirmId": "abc2222222", "action": "schedule.publish", "power": "P2",
            "tenantUuid": "platform", "projectId": "p1", "ownerUserId": 1002,
            "paramsHash": "h2", "status": "CONSUMED",
            "createdAtEpoch": 1750000100.0, "expiresAtEpoch": 1750003700.0,
            "consumedAtEpoch": 1750000200.0,
        },
    }
    history = [
        {"confirmId": "abc1111111", "action": "mes.dispatch", "power": "P3",
         "status": "APPROVED", "tenantUuid": "platform", "projectId": "p1",
         "ownerUserId": 1001, "decidedAtEpoch": 1750000100.0},
        {"confirmId": "abc2222222", "action": "schedule.publish", "power": "P2",
         "status": "APPROVED", "tenantUuid": "platform", "projectId": "p1",
         "ownerUserId": 1002, "decidedAtEpoch": 1750000200.0},
        {"confirmId": "abc2222222", "action": "schedule.publish", "power": "P2",
         "status": "CONSUMED", "tenantUuid": "platform", "projectId": "p1",
         "ownerUserId": 1002, "decidedAtEpoch": 1750000300.0},
    ]
    return {"schemaVersion": 1, "pending": pending, "grants": grants, "history": history}


def _write_file_store(tmp_path: Path) -> Path:
    path = tmp_path / "approvals.json"
    path.write_text(json.dumps(_file_store(), ensure_ascii=False), encoding="utf-8")
    return path


def _counts() -> dict:
    with get_session() as session:
        return {
            "pending": session.execute(select(func.count()).select_from(ApprovalRequestRecord)).scalar(),
            "grants": session.execute(select(func.count()).select_from(ApprovalGrantRecord)).scalar(),
            "events": session.execute(select(func.count()).select_from(ApprovalEventRecord)).scalar(),
        }


def test_migrate_file_to_db_idempotent(database_backend, tmp_path: Path):
    """迁移全量 + 幂等：二次运行全部 skipped，不重复插入。"""
    path = _write_file_store(tmp_path)
    first = migrate_file_to_db(str(path))
    assert first["pending"] == {"migrated": 2, "skipped": 0}
    assert first["grants"] == {"migrated": 2, "skipped": 0}
    assert first["events"] == {"migrated": 3, "skipped": 0}
    assert first["dryRun"] is False
    assert _counts() == {"pending": 2, "grants": 2, "events": 3}

    second = migrate_file_to_db(str(path))
    assert second["pending"] == {"migrated": 0, "skipped": 2}
    assert second["grants"] == {"migrated": 0, "skipped": 2}
    assert second["events"] == {"migrated": 0, "skipped": 3}
    assert _counts() == {"pending": 2, "grants": 2, "events": 3}


def test_migrate_dry_run_does_not_touch_db(database_backend, tmp_path: Path):
    """dry_run：报告数量但库内零写入。"""
    path = _write_file_store(tmp_path)
    report = migrate_file_to_db(str(path), dry_run=True)
    assert report["dryRun"] is True
    assert report["pending"]["migrated"] == 2
    assert report["grants"]["migrated"] == 2
    assert report["events"]["migrated"] == 3
    assert _counts() == {"pending": 0, "grants": 0, "events": 0}


def test_migrate_missing_file_empty_source(database_backend, tmp_path: Path):
    """缺文件 → 空源，全部 0，不抛错。"""
    report = migrate_file_to_db(str(tmp_path / "missing.json"))
    assert report["pending"] == {"migrated": 0, "skipped": 0}
    assert report["grants"] == {"migrated": 0, "skipped": 0}
    assert report["events"] == {"migrated": 0, "skipped": 0}


def test_migrate_requires_database_backend(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
    """未配置 database 后端 → 显式 RuntimeError（fail closed）。"""
    monkeypatch.delenv("APS_APPROVAL_BACKEND", raising=False)
    monkeypatch.delenv("APS_APPROVAL_PATH", raising=False)
    with pytest.raises(RuntimeError, match="APS_APPROVAL_BACKEND=database"):
        migrate_file_to_db(str(tmp_path / "approvals.json"))


def test_migrated_data_readable_via_db_store(database_backend, tmp_path: Path):
    """迁移后 pending/历史可通过 database 后端读回（数据真实生效）。"""
    path = _write_file_store(tmp_path)
    migrate_file_to_db(str(path))
    now = 1749990000.0                      # 合成数据时间窗口内（expiresAt 1750003600 之前）
    pending_items = database_backend.pending_items(
        tenant_uuid="platform", project_id="p1", allowed=lambda _payload: True, now_epoch=now)
    assert len(pending_items) == 2
    assert any(item["confirmId"] == "abc1111111" for item in pending_items)
    history = database_backend.history_items(
        tenant_uuid="platform", project_id="p1", allowed=lambda _payload: True,
        limit=50, now_epoch=now)
    assert len(history) == 3
    assert all(item["status"] in ("APPROVED", "CONSUMED") for item in history)

# ============================================================
# Round 67: fail-closed migration, digest normalization, atomicity
# ============================================================

@pytest.fixture(autouse=True)
def _migration_quiesced(monkeypatch: pytest.MonkeyPatch):
    monkeypatch.setenv("APS_APPROVAL_MIGRATION_QUIESCED", "1")


def _write_payload(tmp_path: Path, payload: object, *, name: str = "round67-approvals.json") -> Path:
    path = tmp_path / name
    path.write_text(json.dumps(payload, ensure_ascii=False), encoding="utf-8")
    return path


def _snapshot_db() -> dict:
    def payload(value: dict) -> str:
        return json.dumps(value, ensure_ascii=False, sort_keys=True, separators=(",", ":"))

    with get_session() as session:
        requests = session.execute(
            select(ApprovalRequestRecord).order_by(ApprovalRequestRecord.confirm_id)
        ).scalars().all()
        grants = session.execute(
            select(ApprovalGrantRecord).order_by(ApprovalGrantRecord.token_hash)
        ).scalars().all()
        events = session.execute(
            select(ApprovalEventRecord).order_by(ApprovalEventRecord.id)
        ).scalars().all()
        return {
            "requests": [(
                row.confirm_id, row.tenant_uuid, row.project_id, row.owner_user_id,
                row.action, row.power, row.params_hash, row.status, row.approval_step,
                row.required_approvals, row.created_at_epoch, row.expires_at_epoch,
                row.revision, payload(row.payload),
            ) for row in requests],
            "grants": [(
                row.token_hash, row.confirm_id, row.tenant_uuid, row.project_id,
                row.owner_user_id, row.action, row.params_hash, row.status,
                row.created_at_epoch, row.expires_at_epoch, row.consumed_at_epoch,
                row.revision, payload(row.payload),
            ) for row in grants],
            "events": [(
                row.id, row.confirm_id, row.tenant_uuid, row.project_id,
                row.owner_user_id, row.action, row.power, row.status,
                row.decided_at_epoch, payload(row.payload),
            ) for row in events],
        }


def _real_file_p3_grant(tmp_path: Path) -> tuple[Path, str, dict]:
    path = tmp_path / "real-file-approvals.json"
    store = ApprovalStore(str(path))
    record = {
        "confirmId": "round67-p3-confirm",
        "sessionId": "round67-session",
        "action": "mes.dispatch",
        "power": "P3",
        "params": {"versionId": 67},
        "paramsHash": "round67-params-hash",
        "tenantUuid": "platform",
        "projectId": "round67-project",
        "ownerUserId": 6701,
        "worldKey": "round67-world",
        "requiredApprovals": 2,
        "approvalStep": 0,
        "approvals": [],
        "createdAtEpoch": 1_800_000_000.0,
        "expiresAtEpoch": 1_900_000_000.0,
    }
    assert store.stage(record, now_epoch=1_800_000_000.0)
    first = store.decide(
        record["confirmId"], approve=True, approver={"userId": 6702, "name": "A"},
        allowed=lambda _record: True, now_epoch=1_800_000_010.0,
        grant_ttl_seconds=3600,
    )
    assert first and first["needsSecondConfirm"] is True
    second = store.decide(
        record["confirmId"], approve=True, approver={"userId": 6703, "name": "B"},
        allowed=lambda _record: True, now_epoch=1_800_000_020.0,
        grant_ttl_seconds=3600,
    )
    assert second and second.get("executionGrant")
    return path, str(second["executionGrant"]), record


def _terminal_grant_source(raw_token: str, *, action: str = "mes.dispatch") -> dict:
    grant = {
        "confirmId": "terminal-confirm",
        "sessionId": "terminal-session",
        "action": action,
        "power": "P3",
        "tenantUuid": "platform",
        "projectId": "terminal-project",
        "ownerUserId": 6801,
        "worldKey": "terminal-world",
        "paramsHash": "terminal-params",
        "approvals": [{"userId": 6802}, {"userId": 6803}],
        "status": "ACTIVE",
        "createdAtEpoch": 1_800_100_000.0,
        "expiresAtEpoch": 1_900_100_000.0,
    }
    event = {
        "confirmId": grant["confirmId"], "sessionId": grant["sessionId"],
        "action": action, "power": "P3", "status": "APPROVED",
        "tenantUuid": "platform", "projectId": grant["projectId"],
        "ownerUserId": grant["ownerUserId"], "worldKey": grant["worldKey"],
        "paramsHash": grant["paramsHash"], "decidedAtEpoch": 1_800_100_010.0,
    }
    return {"schemaVersion": 1, "pending": {}, "grants": {raw_token: grant}, "history": [event]}


def _seed_terminal_request_and_grant(source: dict, token_hash: str, *, grant_action: str | None = None) -> None:
    raw_token, grant = next(iter(source["grants"].items()))
    del raw_token
    with get_session() as session:
        session.add(ApprovalRequestRecord(
            confirm_id=grant["confirmId"], tenant_uuid=grant["tenantUuid"],
            project_id=grant["projectId"], owner_user_id=grant["ownerUserId"],
            action=grant["action"], power=grant["power"], params_hash=grant["paramsHash"],
            status="APPROVED", approval_step=2, required_approvals=2,
            created_at_epoch=grant["createdAtEpoch"], expires_at_epoch=grant["expiresAtEpoch"],
            revision=1, payload=copy.deepcopy(grant),
        ))
        session.add(ApprovalGrantRecord(
            token_hash=token_hash, confirm_id=grant["confirmId"],
            tenant_uuid=grant["tenantUuid"], project_id=grant["projectId"],
            owner_user_id=grant["ownerUserId"], action=grant_action or grant["action"],
            params_hash=grant["paramsHash"], status="ACTIVE",
            created_at_epoch=grant["createdAtEpoch"], expires_at_epoch=grant["expiresAtEpoch"],
            consumed_at_epoch=None, revision=0, payload=copy.deepcopy(grant),
        ))
        session.commit()


def test_real_file_p3_grant_migrates_as_digest_and_consumes_once(database_backend, tmp_path: Path):
    path, raw_grant, record = _real_file_p3_grant(tmp_path)
    migrate_file_to_db(str(path))
    digest = token_digest(raw_grant)
    with get_session() as session:
        assert session.get(ApprovalGrantRecord, raw_grant) is None
        row = session.get(ApprovalGrantRecord, digest)
        assert row is not None
        assert row.confirm_id == record["confirmId"]
        rebuilt = session.get(ApprovalRequestRecord, record["confirmId"])
        assert rebuilt is not None
        assert rebuilt.status == "APPROVED"
    assert raw_grant not in json.dumps(_snapshot_db(), ensure_ascii=False, sort_keys=True)
    kwargs = {
        "confirm_id": record["confirmId"],
        "action": record["action"],
        "params_hash": record["paramsHash"],
        "allowed": lambda _record: True,
        "decided_by": {"userId": 6704},
        "now_epoch": 1_800_000_030.0,
    }
    assert database_backend.consume_grant(raw_grant, **kwargs) is True
    assert database_backend.consume_grant(raw_grant, **kwargs) is False


def test_terminal_grant_without_pending_rebuilds_approved_request(database_backend, tmp_path: Path):
    source = _terminal_grant_source("terminal-token")
    migrate_file_to_db(str(_write_payload(tmp_path, source)))
    with get_session() as session:
        request = session.get(ApprovalRequestRecord, "terminal-confirm")
        assert request is not None
        assert request.status == "APPROVED"
        assert request.action == "mes.dispatch"
        assert request.required_approvals == 2


def _invalid_source(case: str) -> object:
    data = _file_store()
    if case == "top-level-list":
        return []
    if case == "schema-version":
        data["schemaVersion"] = 99
    elif case == "pending-container":
        data["pending"] = []
    elif case == "pending-record":
        data["pending"] = {"bad": "not-an-object"}
    elif case == "grant-container":
        data["grants"] = []
    elif case == "grant-record":
        data["grants"] = {"token": "not-an-object"}
    elif case == "history-container":
        data["history"] = {}
    elif case == "history-record":
        data["history"] = ["not-an-object"]
    elif case == "orphan-grant":
        data = _terminal_grant_source("orphan-token")
        data["history"] = []
    elif case == "mismatched-pending-key":
        data["pending"]["abc1111111"]["confirmId"] = "different-confirm"
    return data


@pytest.mark.parametrize("case", [
    "top-level-list", "schema-version", "pending-container", "pending-record",
    "grant-container", "grant-record", "history-container", "history-record",
    "orphan-grant", "mismatched-pending-key",
])
def test_invalid_source_fails_closed_without_database_writes(database_backend, tmp_path: Path, case: str):
    path = tmp_path / f"invalid-{case}.json"
    path.write_text(json.dumps(_invalid_source(case), ensure_ascii=False), encoding="utf-8")
    with pytest.raises((RuntimeError, ValueError)) as exc:
        migrate_file_to_db(str(path))
    assert str(exc.value)
    assert _counts() == {"pending": 0, "grants": 0, "events": 0}


def test_corrupt_json_fails_closed_without_database_writes(database_backend, tmp_path: Path):
    path = tmp_path / "corrupt.json"
    path.write_text('{"schemaVersion": 1, "pending": ', encoding="utf-8")
    with pytest.raises((RuntimeError, ValueError)):
        migrate_file_to_db(str(path))
    assert _counts() == {"pending": 0, "grants": 0, "events": 0}


def test_migration_requires_explicit_quiesced_flag(database_backend, tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
    path = _write_file_store(tmp_path)
    monkeypatch.delenv("APS_APPROVAL_MIGRATION_QUIESCED", raising=False)
    with pytest.raises(RuntimeError, match="QUIESCED|quiesc"):
        migrate_file_to_db(str(path))
    assert _counts() == {"pending": 0, "grants": 0, "events": 0}


def test_existing_request_immutable_conflict_rolls_back(database_backend, tmp_path: Path):
    data = {"schemaVersion": 1, "pending": {"conflict-confirm": {
        "confirmId": "conflict-confirm", "sessionId": "s", "action": "mes.dispatch",
        "power": "P2", "params": {}, "paramsHash": "expected-hash",
        "tenantUuid": "platform", "projectId": "p", "ownerUserId": 1,
        "createdAtEpoch": 1_800_000_000.0, "expiresAtEpoch": 1_900_000_000.0,
    }}, "grants": {}, "history": []}
    with get_session() as session:
        session.add(ApprovalRequestRecord(
            confirm_id="conflict-confirm", tenant_uuid="platform", project_id="p",
            owner_user_id=1, action="different.action", power="P2",
            params_hash="expected-hash", status="PENDING", approval_step=0,
            required_approvals=1, created_at_epoch=1_800_000_000.0,
            expires_at_epoch=1_900_000_000.0, revision=0,
            payload=copy.deepcopy(data["pending"]["conflict-confirm"]),
        ))
        session.commit()
    before = _snapshot_db()
    with pytest.raises((RuntimeError, ValueError)):
        migrate_file_to_db(str(_write_payload(tmp_path, data)))
    assert _snapshot_db() == before


def test_database_state_may_advance_but_migration_never_regresses_it(database_backend, tmp_path: Path):
    path, raw_grant, record = _real_file_p3_grant(tmp_path)
    migrate_file_to_db(str(path))
    assert database_backend.consume_grant(
        raw_grant, confirm_id=record["confirmId"], action=record["action"],
        params_hash=record["paramsHash"], allowed=lambda _record: True,
        decided_by={"userId": 6704}, now_epoch=1_800_000_030.0,
    )
    with get_session() as session:
        before = session.get(ApprovalGrantRecord, token_digest(raw_grant))
        expected = (before.status, before.consumed_at_epoch, before.revision)
    migrate_file_to_db(str(path))
    with get_session() as session:
        after = session.get(ApprovalGrantRecord, token_digest(raw_grant))
        assert (after.status, after.consumed_at_epoch, after.revision) == expected
        assert after.status == "CONSUMED"


def test_consistent_legacy_raw_token_row_is_repaired_atomically(database_backend, tmp_path: Path):
    raw = "legacy-raw-token-round67"
    source = _terminal_grant_source(raw)
    _seed_terminal_request_and_grant(source, raw)
    migrate_file_to_db(str(_write_payload(tmp_path, source)))
    with get_session() as session:
        assert session.get(ApprovalGrantRecord, raw) is None
        repaired = session.get(ApprovalGrantRecord, token_digest(raw))
        assert repaired is not None
        assert repaired.action == "mes.dispatch"
    grant = next(iter(source["grants"].values()))
    kwargs = {
        "confirm_id": grant["confirmId"],
        "action": grant["action"],
        "params_hash": grant["paramsHash"],
        "allowed": lambda _record: True,
        "decided_by": {"userId": 6704},
        "now_epoch": 1_800_100_100.0,
    }
    assert database_backend.consume_grant(raw, **kwargs) is True
    assert database_backend.consume_grant(raw, **kwargs) is False


def test_legacy_raw_token_payload_conflict_fails_without_changes(
    database_backend,
    tmp_path: Path,
):
    raw = "legacy-payload-conflict-round67"
    source = _terminal_grant_source(raw)
    _seed_terminal_request_and_grant(source, raw)
    with get_session() as session:
        row = session.get(ApprovalGrantRecord, raw)
        assert row is not None
        row.payload = {**copy.deepcopy(row.payload), "action": "forged.action"}
        session.commit()
    before = _snapshot_db()

    with pytest.raises(RuntimeError, match="payload immutable conflict"):
        migrate_file_to_db(str(_write_payload(tmp_path, source)))

    assert _snapshot_db() == before


def test_inconsistent_legacy_raw_token_row_fails_without_changes(database_backend, tmp_path: Path):
    raw = "legacy-raw-token-conflict"
    source = _terminal_grant_source(raw)
    _seed_terminal_request_and_grant(source, raw, grant_action="different.action")
    before = _snapshot_db()
    with pytest.raises((RuntimeError, ValueError)):
        migrate_file_to_db(str(_write_payload(tmp_path, source)))
    assert _snapshot_db() == before


def test_canonical_event_digest_preserves_same_second_near_events_and_is_idempotent(database_backend, tmp_path: Path):
    pending = {
        "confirmId": "event-confirm", "sessionId": "event-session", "action": "mes.dispatch",
        "power": "P3", "params": {}, "paramsHash": "event-hash",
        "tenantUuid": "platform", "projectId": "event-project", "ownerUserId": 1,
        "requiredApprovals": 2, "createdAtEpoch": 1_800_000_000.0,
        "expiresAtEpoch": 1_900_000_000.0,
    }
    common = {
        "confirmId": "event-confirm", "action": "mes.dispatch", "power": "P3",
        "status": "SOD_DENIED", "tenantUuid": "platform", "projectId": "event-project",
        "ownerUserId": 1, "decidedAtEpoch": 1_800_000_010.0,
    }
    events = [
        {**common, "decidedBy": {"userId": 2}, "note": "first", "detail": {"n": 1}},
        {**common, "decidedBy": {"userId": 3}, "note": "second", "detail": {"n": 2}},
    ]
    path = _write_payload(tmp_path, {
        "schemaVersion": 1, "pending": {"event-confirm": pending},
        "grants": {}, "history": events,
    })
    migrate_file_to_db(str(path))
    migrate_file_to_db(str(path))
    with get_session() as session:
        rows = session.execute(select(ApprovalEventRecord).order_by(ApprovalEventRecord.id)).scalars().all()
        assert len(rows) == 2
        assert {row.payload["note"] for row in rows} == {"first", "second"}
        assert {row.payload["decidedBy"]["userId"] for row in rows} == {2, 3}


def _seed_unrelated_target() -> None:
    with get_session() as session:
        session.add(ApprovalRequestRecord(
            confirm_id="existing-target", tenant_uuid="platform", project_id="existing",
            owner_user_id=1, action="existing.action", power="P2", params_hash="existing-hash",
            status="PENDING", approval_step=0, required_approvals=1,
            created_at_epoch=1_800_000_000.0, expires_at_epoch=1_900_000_000.0,
            revision=0, payload={"confirmId": "existing-target", "action": "existing.action"},
        ))
        session.add(ApprovalEventRecord(
            confirm_id="existing-target", tenant_uuid="platform", project_id="existing",
            owner_user_id=1, action="existing.action", power="P2", status="STAGED",
            decided_at_epoch=1_800_000_001.0,
            payload={"confirmId": "existing-target", "action": "existing.action", "status": "STAGED"},
        ))
        session.commit()


def test_late_event_construction_failure_rolls_back_all_tables(database_backend, tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
    _seed_unrelated_target()
    before = _snapshot_db()
    source = _terminal_grant_source("late-construction-token")
    path = _write_payload(tmp_path, source)

    def explode_event(*_args, **_kwargs):
        raise RuntimeError("injected event construction failure")

    monkeypatch.setattr(ApprovalEventRecord, "__init__", explode_event)
    with pytest.raises(RuntimeError):
        migrate_file_to_db(str(path))
    assert _snapshot_db() == before


def test_flush_failure_rolls_back_all_tables_and_existing_target(database_backend, tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
    _seed_unrelated_target()
    before = _snapshot_db()
    path = _write_payload(tmp_path, _terminal_grant_source("flush-failure-token"))
    original_flush = Session.flush

    def fail_flush(self, *_args, **_kwargs):
        if self.new:
            raise RuntimeError("injected flush failure")
        return original_flush(self, *_args, **_kwargs)

    monkeypatch.setattr(Session, "flush", fail_flush)
    with pytest.raises(RuntimeError):
        migrate_file_to_db(str(path))
    monkeypatch.setattr(Session, "flush", original_flush)
    assert _snapshot_db() == before


def test_source_digest_drift_after_flush_rolls_back(database_backend, tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
    _seed_unrelated_target()
    before = _snapshot_db()
    path = _write_payload(tmp_path, _terminal_grant_source("source-drift-token"))
    original_flush = Session.flush
    mutated = False

    def drift_then_flush(self, *_args, **_kwargs):
        nonlocal mutated
        if self.new and not mutated:
            mutated = True
            changed = json.loads(path.read_text(encoding="utf-8"))
            changed["history"][0]["note"] = "changed-after-load"
            path.write_text(json.dumps(changed, ensure_ascii=False), encoding="utf-8")
        return original_flush(self, *_args, **_kwargs)

    monkeypatch.setattr(Session, "flush", drift_then_flush)
    with pytest.raises((RuntimeError, ValueError)):
        migrate_file_to_db(str(path))
    monkeypatch.setattr(Session, "flush", original_flush)
    assert mutated is True
    assert _snapshot_db() == before


def test_migration_holds_file_backend_lock_through_database_flush(database_backend, tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
    path = _write_payload(tmp_path, _terminal_grant_source("lock-token"))
    writer = ApprovalStore(str(path))
    original_flush = Session.flush
    flush_entered = threading.Event()
    release_flush = threading.Event()
    writer_started = threading.Event()
    writer_done = threading.Event()
    migration_errors: list[BaseException] = []
    writer_results: list[bool] = []

    def blocked_flush(self, *_args, **_kwargs):
        if self.new and not flush_entered.is_set():
            flush_entered.set()
            if not release_flush.wait(5):
                raise RuntimeError("test did not release migration flush")
        return original_flush(self, *_args, **_kwargs)

    monkeypatch.setattr(Session, "flush", blocked_flush)

    def migrate() -> None:
        try:
            migrate_file_to_db(str(path))
        except BaseException as exc:  # noqa: BLE001 - captured for test-thread assertion
            migration_errors.append(exc)

    def write_file() -> None:
        writer_started.set()
        writer_results.append(writer.stage({
            "confirmId": "writer-after-migration", "action": "schedule.publish",
            "power": "P2", "paramsHash": "writer-hash", "tenantUuid": "platform",
            "projectId": "terminal-project", "createdAtEpoch": 1_800_200_000.0,
            "expiresAtEpoch": 1_900_200_000.0,
        }, now_epoch=1_800_200_000.0))
        writer_done.set()

    migration_thread = threading.Thread(target=migrate, daemon=True)
    writer_thread = threading.Thread(target=write_file, daemon=True)
    migration_thread.start()
    assert flush_entered.wait(5), "migration never reached database flush"
    writer_thread.start()
    assert writer_started.wait(2)
    blocked_by_same_lock = not writer_done.wait(0.25)
    release_flush.set()
    migration_thread.join(5)
    writer_thread.join(5)
    monkeypatch.setattr(Session, "flush", original_flush)
    assert blocked_by_same_lock, "file writer was not blocked by the migration lock"
    assert not migration_thread.is_alive()
    assert not writer_thread.is_alive()
    assert migration_errors == []
    assert writer_results == [True]