mnemosyne/tests/test_fidelity.py

"""Tests for the multi-fidelity state machine."""

from __future__ import annotations

from mnemosyne.fidelity import (
    VALID_OBJECT_TYPES,
    FidelityLevel,
    FidelityManager,
    PressureZone,
    SemanticObject,
    _estimate_tokens,
    make_object,
)

# ── Helpers ──────────────────────────────────────────────────


def _make_obj(
    content: str = "x" * 400,
    *,
    object_type: str = "file_context",
    turn: int = 0,
    summary_detailed: str | None = None,
    summary_compact: str | None = None,
    stub: str | None = None,
) -> SemanticObject:
    """Create a SemanticObject with sensible defaults for testing."""
    return make_object(
        object_type=object_type,
        content_full=content,
        created_at_turn=turn,
        summary_detailed=summary_detailed or ("summary " * 20),  # ~140 chars
        summary_compact=summary_compact or ("compact " * 5),  # ~40 chars
        stub=stub or "file_context: test object",
    )


def _fill_manager(
    manager: FidelityManager,
    count: int,
    *,
    content_size: int = 400,
    turn: int = 0,
) -> list[str]:
    """Register `count` objects and return their IDs."""
    ids = []
    for i in range(count):
        obj = _make_obj("x" * content_size, turn=turn + i)
        oid = manager.register_object(obj)
        ids.append(oid)
    return ids


# ── FidelityLevel enum ───────────────────────────────────────


class TestFidelityLevel:
    def test_five_levels(self):
        assert len(FidelityLevel) == 5

    def test_ordering(self):
        assert FidelityLevel.L0 < FidelityLevel.L1 < FidelityLevel.L2
        assert FidelityLevel.L2 < FidelityLevel.L3 < FidelityLevel.L4

    def test_values(self):
        assert FidelityLevel.L0 == 0
        assert FidelityLevel.L4 == 4

    def test_names(self):
        assert FidelityLevel.L0.name == "L0"
        assert FidelityLevel.L4.name == "L4"


# ── PressureZone enum ────────────────────────────────────────


class TestPressureZone:
    def test_five_zones(self):
        assert len(PressureZone) == 5

    def test_ordering(self):
        assert PressureZone.NORMAL < PressureZone.CAUTION
        assert PressureZone.CAUTION < PressureZone.WARNING
        assert PressureZone.WARNING < PressureZone.CRITICAL
        assert PressureZone.CRITICAL < PressureZone.EMERGENCY

    def test_names(self):
        expected = {"NORMAL", "CAUTION", "WARNING", "CRITICAL", "EMERGENCY"}
        assert {z.name for z in PressureZone} == expected


# ── SemanticObject ────────────────────────────────────────────


class TestSemanticObject:
    def test_required_fields(self):
        obj = _make_obj()
        assert obj.id
        assert obj.object_type == "file_context"
        assert obj.content_full == "x" * 400
        assert obj.current_fidelity == FidelityLevel.L0
        assert obj.pinned is False
        assert obj.pin_until_turn is None
        assert obj.fault_count == 0

    def test_token_estimation(self):
        obj = _make_obj("a" * 1000)
        assert obj.token_count_l0 == 250  # 1000 / 4

    def test_tokens_at_each_level(self):
        obj = _make_obj(
            "a" * 400,
            summary_detailed="b" * 120,
            summary_compact="c" * 20,
            stub="d" * 100,
        )
        assert obj.tokens_at(FidelityLevel.L0) == 100  # 400/4
        assert obj.tokens_at(FidelityLevel.L1) == 30  # 120/4
        assert obj.tokens_at(FidelityLevel.L2) == 5  # 20/4
        assert obj.tokens_at(FidelityLevel.L3) == 25  # 100/4
        assert obj.tokens_at(FidelityLevel.L4) == 0  # evicted

    def test_current_tokens_tracks_fidelity(self):
        obj = _make_obj("a" * 400, summary_detailed="b" * 120)
        assert obj.current_tokens == 100  # L0: 400/4
        obj.current_fidelity = FidelityLevel.L1
        assert obj.current_tokens == 30  # L1: 120/4

    def test_losses_default_empty(self):
        obj = _make_obj()
        assert obj.losses_l1 == []
        assert obj.losses_l2 == []

    def test_losses_populated(self):
        obj = make_object(
            object_type="design_decision",
            content_full="decision content",
            losses_l1=["exact error codes"],
            losses_l2=["exact error codes", "function signatures"],
        )
        assert "exact error codes" in obj.losses_l1
        assert len(obj.losses_l2) == 2

    def test_valid_object_types(self):
        expected = {
            "conversation_phase",
            "design_decision",
            "debugging_session",
            "file_context",
            "tool_result",
            "plan",
            "error_context",
            "external_reference",
        }
        assert VALID_OBJECT_TYPES == expected

    def test_queryability_fields(self):
        obj = make_object(
            object_type="file_context",
            content_full="content",
            can_answer=["what functions are defined"],
            fault_when=["need exact line numbers"],
            key_entities=["auth.py", "middleware"],
        )
        assert obj.can_answer == ["what functions are defined"]
        assert obj.fault_when == ["need exact line numbers"]
        assert obj.key_entities == ["auth.py", "middleware"]


# ── Token estimation ──────────────────────────────────────────


class TestTokenEstimation:
    def test_basic(self):
        assert _estimate_tokens("a" * 100) == 25

    def test_none(self):
        assert _estimate_tokens(None) == 0

    def test_empty(self):
        # len("") = 0, 0 // 4 = 0, max(1, 0) = 1
        assert _estimate_tokens("") == 1

    def test_empty_returns_minimum(self):
        # Empty string: len=0, 0//4=0, max(1,0)=1
        assert _estimate_tokens("") == 1

    def test_short(self):
        assert _estimate_tokens("hi") == 1  # 2//4=0, max(1,0)=1

    def test_exact_multiple(self):
        assert _estimate_tokens("a" * 400) == 100


# ── make_object factory ───────────────────────────────────────


class TestMakeObject:
    def test_generates_id(self):
        obj = make_object(object_type="plan", content_full="plan content")
        assert len(obj.id) == 16
        assert obj.id.isalnum()

    def test_unique_ids(self):
        ids = {make_object(object_type="plan", content_full="x").id for _ in range(100)}
        assert len(ids) == 100

    def test_auto_token_estimates(self):
        obj = make_object(
            object_type="file_context",
            content_full="a" * 800,
            summary_detailed="b" * 240,
            summary_compact="c" * 40,
            stub="d" * 100,
        )
        assert obj.token_count_l0 == 200
        assert obj.token_count_l1 == 60
        assert obj.token_count_l2 == 10
        assert obj.token_count_l3 == 25  # 100/4

    def test_default_stub_tokens(self):
        obj = make_object(object_type="plan", content_full="content")
        assert obj.token_count_l3 == 25  # default when no stub provided

    def test_starts_at_l0(self):
        obj = make_object(object_type="plan", content_full="content")
        assert obj.current_fidelity == FidelityLevel.L0


# ── FidelityManager basics ────────────────────────────────────


class TestFidelityManagerBasics:
    def test_default_window_size(self):
        fm = FidelityManager()
        assert fm.window_size == 200_000

    def test_custom_window_size(self):
        fm = FidelityManager(window_size=100_000)
        assert fm.window_size == 100_000

    def test_register_and_get(self):
        fm = FidelityManager()
        obj = _make_obj()
        oid = fm.register_object(obj)
        assert fm.get_object(oid) is obj

    def test_get_nonexistent(self):
        fm = FidelityManager()
        assert fm.get_object("nonexistent") is None

    def test_register_returns_id(self):
        fm = FidelityManager()
        obj = _make_obj()
        oid = fm.register_object(obj)
        assert oid == obj.id

    def test_total_tokens_empty(self):
        fm = FidelityManager()
        assert fm.total_tokens() == 0

    def test_total_tokens_sums_current_fidelity(self):
        fm = FidelityManager()
        obj1 = _make_obj("a" * 400)  # 100 tokens at L0
        obj2 = _make_obj("b" * 800)  # 200 tokens at L0
        fm.register_object(obj1)
        fm.register_object(obj2)
        assert fm.total_tokens() == 300

    def test_total_tokens_respects_fidelity_change(self):
        fm = FidelityManager()
        obj = _make_obj("a" * 400, summary_detailed="b" * 120)
        fm.register_object(obj)
        assert fm.total_tokens() == 100  # L0: 400/4
        obj.current_fidelity = FidelityLevel.L1
        assert fm.total_tokens() == 30  # L1: 120/4


# ── Pressure zones ────────────────────────────────────────────


class TestPressureZones:
    def test_normal_zone(self):
        fm = FidelityManager(window_size=1000)
        # 400 chars = 100 tokens, 10% of 1000 → NORMAL
        _fill_manager(fm, 1, content_size=400)
        assert fm.current_pressure() == PressureZone.NORMAL

    def test_caution_zone(self):
        fm = FidelityManager(window_size=1000)
        # 2400 chars = 600 tokens, 60% of 1000 → CAUTION
        _fill_manager(fm, 1, content_size=2400)
        assert fm.current_pressure() == PressureZone.CAUTION

    def test_warning_zone(self):
        fm = FidelityManager(window_size=1000)
        # 3200 chars = 800 tokens, 80% of 1000 → WARNING
        _fill_manager(fm, 1, content_size=3200)
        assert fm.current_pressure() == PressureZone.WARNING

    def test_critical_zone(self):
        fm = FidelityManager(window_size=1000)
        # 3600 chars = 900 tokens, 90% of 1000 → CRITICAL
        _fill_manager(fm, 1, content_size=3600)
        assert fm.current_pressure() == PressureZone.CRITICAL

    def test_emergency_zone(self):
        fm = FidelityManager(window_size=1000)
        # 3840 chars = 960 tokens, 96% of 1000 → EMERGENCY
        _fill_manager(fm, 1, content_size=3840)
        assert fm.current_pressure() == PressureZone.EMERGENCY

    def test_exact_boundary_50pct(self):
        fm = FidelityManager(window_size=1000)
        # 2000 chars = 500 tokens, exactly 50% → CAUTION (>= threshold)
        _fill_manager(fm, 1, content_size=2000)
        assert fm.current_pressure() == PressureZone.CAUTION

    def test_just_below_50pct(self):
        fm = FidelityManager(window_size=1000)
        # 1996 chars = 499 tokens, 49.9% → NORMAL
        _fill_manager(fm, 1, content_size=1996)
        assert fm.current_pressure() == PressureZone.NORMAL

    def test_zero_window_is_emergency(self):
        fm = FidelityManager(window_size=0)
        assert fm.current_pressure() == PressureZone.EMERGENCY


# ── Degradation ───────────────────────────────────────────────


class TestDegradation:
    def test_no_degradation_in_normal(self):
        fm = FidelityManager(window_size=10_000)
        _fill_manager(fm, 1, content_size=400)  # 100 tokens, 1% → NORMAL
        transitions = fm.degrade(current_turn=1)
        assert transitions == []

    def test_caution_degrades_l0_to_l1(self):
        fm = FidelityManager(window_size=1000)
        # 2400 chars = 600 tokens → CAUTION
        _fill_manager(fm, 3, content_size=800)
        assert fm.current_pressure() == PressureZone.CAUTION

        transitions = fm.degrade(current_turn=5)
        # Should have degraded some L0 objects to L1
        assert len(transitions) > 0
        for _oid, old, new in transitions:
            assert old == FidelityLevel.L0
            assert new == FidelityLevel.L1

    def test_caution_degrades_oldest_first(self):
        fm = FidelityManager(window_size=1000)
        # Create objects at different turns
        # 1200 chars each = 300 tokens each, 600 total = 60% → CAUTION
        obj_old = _make_obj("a" * 1200, turn=0)
        obj_new = _make_obj("b" * 1200, turn=5)
        id_old = fm.register_object(obj_old)
        id_new = fm.register_object(obj_new)

        # Mark new one as recently accessed
        fm.mark_accessed(id_new, current_turn=10)

        assert fm.current_pressure() == PressureZone.CAUTION

        transitions = fm.degrade(current_turn=10)
        # Oldest should be degraded first
        if transitions:
            assert transitions[0][0] == id_old

    def test_warning_degrades_multiple_levels(self):
        fm = FidelityManager(window_size=1000)
        # 3200 chars = 800 tokens → WARNING
        _fill_manager(fm, 4, content_size=800)
        assert fm.current_pressure() == PressureZone.WARNING

        transitions = fm.degrade(current_turn=10)
        assert len(transitions) > 0
        # Should see L0→L1 transitions at minimum
        levels_seen = {(old, new) for _, old, new in transitions}
        assert (FidelityLevel.L0, FidelityLevel.L1) in levels_seen

    def test_critical_degrades_aggressively(self):
        fm = FidelityManager(window_size=1000)
        # 3600 chars = 900 tokens → CRITICAL
        _fill_manager(fm, 3, content_size=1200)
        assert fm.current_pressure() == PressureZone.CRITICAL

        transitions = fm.degrade(current_turn=10)
        assert len(transitions) > 0
        # Should see objects pushed to L3 or L4
        final_levels = {new for _, _, new in transitions}
        assert FidelityLevel.L3 in final_levels or FidelityLevel.L4 in final_levels

    def test_emergency_evicts_all_unpinned(self):
        fm = FidelityManager(window_size=1000)
        # 3840 chars = 960 tokens → EMERGENCY
        ids = _fill_manager(fm, 4, content_size=960)
        assert fm.current_pressure() == PressureZone.EMERGENCY

        fm.degrade(current_turn=10)
        # All objects should end at L4
        for obj_id in ids:
            obj = fm.get_object(obj_id)
            assert obj is not None
            assert obj.current_fidelity == FidelityLevel.L4

    def test_emergency_respects_pins(self):
        fm = FidelityManager(window_size=1000)
        ids = _fill_manager(fm, 4, content_size=960)

        # Pin one object
        fm.record_fault(ids[0], current_turn=5, pin_duration=20)

        fm.degrade(current_turn=10)
        # Pinned object should NOT be at L4
        pinned_obj = fm.get_object(ids[0])
        assert pinned_obj is not None
        assert pinned_obj.current_fidelity < FidelityLevel.L4

        # Others should be at L4
        for oid in ids[1:]:
            obj = fm.get_object(oid)
            assert obj is not None
            assert obj.current_fidelity == FidelityLevel.L4

    def test_degrade_returns_transitions(self):
        fm = FidelityManager(window_size=1000)
        _fill_manager(fm, 3, content_size=800)
        transitions = fm.degrade(current_turn=5)
        for oid, old, new in transitions:
            assert isinstance(oid, str)
            assert isinstance(old, FidelityLevel)
            assert isinstance(new, FidelityLevel)
            assert new > old  # Degradation means higher numeric level

    def test_degrade_stops_when_pressure_relieved(self):
        fm = FidelityManager(window_size=1000)
        # Create objects with large L0 but small L1
        for i in range(3):
            obj = _make_obj(
                "a" * 800,  # 200 tokens at L0
                summary_detailed="b" * 40,  # 10 tokens at L1
                turn=i,
            )
            fm.register_object(obj)

        # 600 tokens → CAUTION
        assert fm.current_pressure() == PressureZone.CAUTION

        fm.degrade(current_turn=5)
        # After degrading enough objects, pressure should drop
        # Not all objects need to be degraded
        assert fm.current_pressure() <= PressureZone.CAUTION


# ── Upgrade ───────────────────────────────────────────────────


class TestUpgrade:
    def test_upgrade_l1_to_l0(self):
        fm = FidelityManager()
        obj = _make_obj("content" * 50)
        oid = fm.register_object(obj)
        obj.current_fidelity = FidelityLevel.L1

        result = fm.upgrade(oid, FidelityLevel.L0, current_turn=5)
        assert result is True
        assert obj.current_fidelity == FidelityLevel.L0

    def test_upgrade_updates_last_accessed(self):
        fm = FidelityManager()
        obj = _make_obj("content" * 50)
        oid = fm.register_object(obj)
        obj.current_fidelity = FidelityLevel.L2

        fm.upgrade(oid, FidelityLevel.L0, current_turn=42)
        assert obj.last_accessed_turn == 42

    def test_upgrade_rejects_same_level(self):
        fm = FidelityManager()
        obj = _make_obj()
        oid = fm.register_object(obj)

        result = fm.upgrade(oid, FidelityLevel.L0, current_turn=5)
        assert result is False  # Already at L0

    def test_upgrade_rejects_downgrade(self):
        fm = FidelityManager()
        obj = _make_obj()
        oid = fm.register_object(obj)

        result = fm.upgrade(oid, FidelityLevel.L1, current_turn=5)
        assert result is False  # L1 > L0, not an upgrade

    def test_upgrade_nonexistent_object(self):
        fm = FidelityManager()
        result = fm.upgrade("nonexistent", FidelityLevel.L0, current_turn=5)
        assert result is False

    def test_upgrade_l3_to_l1(self):
        fm = FidelityManager()
        obj = _make_obj(summary_detailed="detailed summary content")
        oid = fm.register_object(obj)
        obj.current_fidelity = FidelityLevel.L3

        result = fm.upgrade(oid, FidelityLevel.L1, current_turn=10)
        assert result is True
        assert obj.current_fidelity == FidelityLevel.L1

    def test_upgrade_requires_content_at_target(self):
        fm = FidelityManager()
        obj = make_object(
            object_type="file_context",
            content_full="full content",
            # No summary_detailed provided
        )
        oid = fm.register_object(obj)
        obj.current_fidelity = FidelityLevel.L3

        # Can upgrade to L0 (has content_full)
        result = fm.upgrade(oid, FidelityLevel.L0, current_turn=5)
        assert result is True

    def test_upgrade_rejects_missing_l1_content(self):
        fm = FidelityManager()
        obj = SemanticObject(
            id="test123",
            object_type="file_context",
            content_full="full",
            summary_detailed=None,  # No L1 content
            token_count_l0=1,
        )
        fm.register_object(obj)
        obj.current_fidelity = FidelityLevel.L3

        result = fm.upgrade("test123", FidelityLevel.L1, current_turn=5)
        assert result is False


# ── Fault-driven pinning ──────────────────────────────────────


class TestFaultPinning:
    def test_record_fault_pins_object(self):
        fm = FidelityManager()
        obj = _make_obj()
        oid = fm.register_object(obj)

        fm.record_fault(oid, current_turn=10, pin_duration=5)
        assert obj.pinned is True
        assert obj.pin_until_turn == 15
        assert obj.fault_count == 1

    def test_record_fault_updates_access(self):
        fm = FidelityManager()
        obj = _make_obj()
        oid = fm.register_object(obj)

        fm.record_fault(oid, current_turn=10)
        assert obj.last_accessed_turn == 10

    def test_multiple_faults_increment_count(self):
        fm = FidelityManager()
        obj = _make_obj()
        oid = fm.register_object(obj)

        fm.record_fault(oid, current_turn=10)
        fm.record_fault(oid, current_turn=12)
        assert obj.fault_count == 2

    def test_pin_prevents_degradation(self):
        fm = FidelityManager(window_size=1000)
        ids = _fill_manager(fm, 3, content_size=800)

        # Pin the oldest object
        fm.record_fault(ids[0], current_turn=5, pin_duration=20)

        transitions = fm.degrade(current_turn=10)
        # Pinned object should not appear in transitions
        degraded_ids = {oid for oid, _, _ in transitions}
        assert ids[0] not in degraded_ids

    def test_pin_expires(self):
        fm = FidelityManager(window_size=1000)
        ids = _fill_manager(fm, 3, content_size=800)

        fm.record_fault(ids[0], current_turn=5, pin_duration=3)
        # Pin expires at turn 8

        fm.degrade(current_turn=9)
        # Now the object can be degraded
        obj = fm.get_object(ids[0])
        assert obj is not None
        assert obj.pinned is False

    def test_default_pin_duration(self):
        fm = FidelityManager()
        obj = _make_obj()
        oid = fm.register_object(obj)

        fm.record_fault(oid, current_turn=10)
        assert obj.pin_until_turn == 15  # default duration = 5

    def test_fault_nonexistent_object(self):
        fm = FidelityManager()
        # Should not raise
        fm.record_fault("nonexistent", current_turn=10)


# ── mark_accessed ─────────────────────────────────────────────


class TestMarkAccessed:
    def test_updates_last_accessed(self):
        fm = FidelityManager()
        obj = _make_obj(turn=0)
        oid = fm.register_object(obj)

        fm.mark_accessed(oid, current_turn=42)
        assert obj.last_accessed_turn == 42

    def test_nonexistent_object(self):
        fm = FidelityManager()
        # Should not raise
        fm.mark_accessed("nonexistent", current_turn=10)


# ── eviction_candidates ──────────────────────────────────────


class TestEvictionCandidates:
    def test_empty_manager(self):
        fm = FidelityManager()
        assert fm.eviction_candidates(current_turn=0) == []

    def test_excludes_l4_objects(self):
        fm = FidelityManager()
        obj = _make_obj()
        fm.register_object(obj)
        obj.current_fidelity = FidelityLevel.L4

        candidates = fm.eviction_candidates(current_turn=0)
        assert len(candidates) == 0

    def test_unpinned_before_pinned(self):
        fm = FidelityManager()
        obj_pinned = _make_obj(turn=0)
        obj_free = _make_obj(turn=1)
        id_pinned = fm.register_object(obj_pinned)
        id_free = fm.register_object(obj_free)

        fm.record_fault(id_pinned, current_turn=5, pin_duration=20)

        candidates = fm.eviction_candidates(current_turn=6)
        assert len(candidates) == 2
        assert candidates[0].id == id_free  # Unpinned first

    def test_older_access_more_evictable(self):
        fm = FidelityManager()
        obj_old = _make_obj(turn=0)
        obj_new = _make_obj(turn=0)
        id_old = fm.register_object(obj_old)
        id_new = fm.register_object(obj_new)

        fm.mark_accessed(id_new, current_turn=10)

        candidates = fm.eviction_candidates(current_turn=10)
        assert candidates[0].id == id_old

    def test_lower_fidelity_more_evictable(self):
        fm = FidelityManager()
        obj_l0 = _make_obj(turn=0)
        obj_l3 = _make_obj(turn=0)
        fm.register_object(obj_l0)
        id_l3 = fm.register_object(obj_l3)
        obj_l3.current_fidelity = FidelityLevel.L3

        candidates = fm.eviction_candidates(current_turn=0)
        # L3 (closer to eviction) should come first
        assert candidates[0].id == id_l3

    def test_expired_pins_are_evictable(self):
        fm = FidelityManager()
        obj = _make_obj(turn=0)
        oid = fm.register_object(obj)

        fm.record_fault(oid, current_turn=5, pin_duration=3)
        # Pin expires at turn 8

        candidates = fm.eviction_candidates(current_turn=9)
        assert len(candidates) == 1
        assert candidates[0].pinned is False


# ── objects_at_fidelity ───────────────────────────────────────


class TestObjectsAtFidelity:
    def test_all_at_l0(self):
        fm = FidelityManager()
        _fill_manager(fm, 3)
        assert len(fm.objects_at_fidelity(FidelityLevel.L0)) == 3
        assert len(fm.objects_at_fidelity(FidelityLevel.L1)) == 0

    def test_mixed_levels(self):
        fm = FidelityManager()
        ids = _fill_manager(fm, 3)
        obj0 = fm.get_object(ids[0])
        obj1 = fm.get_object(ids[1])
        assert obj0 is not None
        assert obj1 is not None
        obj0.current_fidelity = FidelityLevel.L1
        obj1.current_fidelity = FidelityLevel.L3

        assert len(fm.objects_at_fidelity(FidelityLevel.L0)) == 1
        assert len(fm.objects_at_fidelity(FidelityLevel.L1)) == 1
        assert len(fm.objects_at_fidelity(FidelityLevel.L3)) == 1


# ── summary ───────────────────────────────────────────────────


class TestSummary:
    def test_summary_structure(self):
        fm = FidelityManager(window_size=10_000)
        _fill_manager(fm, 2, content_size=400)

        s = fm.summary()
        assert "total_objects" in s
        assert "total_tokens" in s
        assert "window_size" in s
        assert "pressure_zone" in s
        assert "objects_by_level" in s
        assert "pinned_count" in s
        assert "total_faults" in s

    def test_summary_values(self):
        fm = FidelityManager(window_size=10_000)
        ids = _fill_manager(fm, 3, content_size=400)
        fm.record_fault(ids[0], current_turn=5)

        s = fm.summary()
        assert s["total_objects"] == 3
        assert s["total_tokens"] == 300  # 3 * 100
        assert s["window_size"] == 10_000
        assert s["pressure_zone"] == "NORMAL"
        assert s["objects_by_level"]["L0"] == 3
        assert s["pinned_count"] == 1
        assert s["total_faults"] == 1


# ── Integration: full lifecycle ───────────────────────────────


class TestIntegration:
    def test_register_degrade_upgrade_cycle(self):
        """Full lifecycle: register → pressure → degrade → access → upgrade."""
        fm = FidelityManager(window_size=500)

        # Register objects that push into CAUTION
        ids = []
        for i in range(5):
            obj = _make_obj(
                "x" * 400,  # 100 tokens each
                summary_detailed="y" * 120,  # 30 tokens
                summary_compact="z" * 20,  # 5 tokens
                stub="stub text",
                turn=i,
            )
            ids.append(fm.register_object(obj))

        # 500 tokens in 500 window → 100% → EMERGENCY
        assert fm.current_pressure() == PressureZone.EMERGENCY

        # Degrade
        transitions = fm.degrade(current_turn=10)
        assert len(transitions) > 0

        # All should be evicted (emergency)
        for oid in ids:
            obj = fm.get_object(oid)
            assert obj is not None
            assert obj.current_fidelity == FidelityLevel.L4

        # Upgrade one back to L0
        result = fm.upgrade(ids[0], FidelityLevel.L0, current_turn=11)
        assert result is True
        upgraded = fm.get_object(ids[0])
        assert upgraded is not None
        assert upgraded.current_fidelity == FidelityLevel.L0

    def test_fault_pin_degrade_cycle(self):
        """Fault → pin → degrade respects pin → pin expires → degrade works."""
        fm = FidelityManager(window_size=1000)
        ids = _fill_manager(fm, 4, content_size=800)

        # Record fault on first object
        fm.record_fault(ids[0], current_turn=5, pin_duration=3)

        # Degrade at turn 6 — pinned object survives
        transitions = fm.degrade(current_turn=6)
        degraded_ids = {oid for oid, _, _ in transitions}
        assert ids[0] not in degraded_ids

        # At turn 9, pin expired — now it can be degraded
        obj = fm.get_object(ids[0])
        assert obj is not None
        # Reset to L0 for clean test
        obj.current_fidelity = FidelityLevel.L0

        # Re-fill to get pressure back up
        _fill_manager(fm, 2, content_size=800, turn=9)

        fm.degrade(current_turn=9)
        # Now the previously-pinned object should be degradable
        obj_after = fm.get_object(ids[0])
        assert obj_after is not None
        assert obj_after.pinned is False

    def test_token_accounting_through_degradation(self):
        """Token count decreases as objects are degraded."""
        fm = FidelityManager(window_size=1000)

        for i in range(3):
            obj = _make_obj(
                "a" * 800,  # 200 tokens at L0
                summary_detailed="b" * 120,  # 30 tokens at L1
                turn=i,
            )
            fm.register_object(obj)

        initial_tokens = fm.total_tokens()
        assert initial_tokens == 600  # 3 * 200

        fm.degrade(current_turn=10)

        # Tokens should have decreased
        assert fm.total_tokens() < initial_tokens

    def test_multiple_degrade_passes(self):
        """Multiple degrade calls progressively reduce fidelity."""
        fm = FidelityManager(window_size=200)

        for i in range(3):
            obj = _make_obj(
                "a" * 400,  # 100 tokens at L0
                summary_detailed="b" * 120,  # 30 tokens at L1
                summary_compact="c" * 20,  # 5 tokens at L2
                stub="stub",
                turn=i,
            )
            fm.register_object(obj)

        # 300 tokens in 200 window → EMERGENCY
        fm.degrade(current_turn=10)

        # After emergency, all should be L4
        for obj in fm._objects.values():
            assert obj.current_fidelity == FidelityLevel.L4