dreamwell-runtime 1.0.0

// SimulationService — the DreamRealityContainer.
//
// Dual-purpose: Studio→Play preview AND Published .exe builds.
// Manages the full play lifecycle: Braid mount → reality check → scene instantiation
// → CausalComputeKernel init → GPU sync → stitch → first frame confirmation → frame loop → shutdown.
//
// Input is NEVER enabled before the 7-step initialization completes.
// The Seer must be Happy.
//
// Uses CausalComputeKernel + SDK Decoherence instead of ParticleController.
// Every input is dispatched through Oracle as a SacredWeave with BLAKE3 attestation.

use dreamwell_attention::encoder::CausalEngineEncoder;
use dreamwell_attention::{CausalComputeKernel, InputPacket, KernelResult};
use dreamwell_engine::game_object::GameObjectScene;
use dreamwell_engine::input::particle::particle_sphere_offsets;
use dreamwell_engine::physics::simulation::SuperpositionObserver;
use dreamwell_fabric::causal_observer_lane::{causal_observer_lane_channel, CausalObserverLaneReceiver};
use dreamwell_gates::{DreamGate, GateConfig};
use dreamwell_gpu::quantum_bridge::QuantumBridge;
use dreamwell_sdk::{
    decohere::{Decoherence, DecoherenceConfig, DecoherenceInputMode},
    ledger_lane_channel,
    loom_budgeter::LoomBudgeter,
    loom_limiter::LoomLimiter,
    LedgerLaneReceiver, Oracle, OracleConfig,
};

/// Simulation mode discriminator.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SimulationMode {
    /// Studio→Play preview (editor-hosted).
    Preview,
    /// Published standalone build.
    Published,
}

/// Runtime readiness signal — mirrors editor RuntimeReadiness.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum RuntimeReadiness {
    Pending,
    Syncing,
    Ready,
    Failed,
}

/// A journal entry for the simulation session.
#[derive(Debug, Clone)]
pub struct SimulationJournalEntry {
    pub frame: u64,
    pub kind: String,
    pub detail: String,
}

/// SimulationService — the DreamRealityContainer.
pub struct SimulationService {
    /// Active scene objects.
    pub scene: GameObjectScene,
    /// CausalComputeKernel — synced from encoder for collision/POI checks.
    pub kernel: Option<CausalComputeKernel>,
    /// CausalEngineEncoder — authoritative encode boundary (wraps SuperBodyController → Kernel).
    pub encoder: Option<CausalEngineEncoder>,
    /// QuantumBridge — formal CPU→GPU transfer with DreamMemory + SacredSeal.
    pub bridge: Option<QuantumBridge>,
    /// Last bridge packet for decoder path (app.rs consumes this).
    pub last_bridge_packet: Option<dreamwell_gpu::quantum_bridge::BridgePacket>,
    /// SDK Decoherence facade (input → Weave → Oracle).
    pub decoherence: Option<Decoherence>,
    /// Oracle — SacredPath validation + BLAKE3 attestation router.
    pub oracle: Option<Oracle>,
    /// Spatial decoherence zones from scene tags.
    pub decoherence_fields: Vec<dreamwell_quantum::DecoherenceField>,
    /// Last kernel tick result for rendering.
    pub last_result: Option<KernelResult>,
    /// Last SuperBody frame descriptor for GPU upload (backward compat).
    pub last_descriptor: Option<dreamwell_attention::SuperBodyFrameDescriptor>,
    /// Player entity ID (CanonicalObserverObject).
    pub player_object_id: u64,
    /// Pre-computed sphere offsets for particle particles.
    pub particle_offsets: Vec<[f32; 3]>,
    /// Observer context for quantum culling.
    pub observer: SuperpositionObserver,
    /// Session journal.
    pub journal: Vec<SimulationJournalEntry>,
    /// Console messages (for UI display).
    pub console: Vec<String>,
    /// Simulation mode.
    pub mode: SimulationMode,
    /// Readiness signal — input is gated on this.
    pub readiness: RuntimeReadiness,
    /// Current frame index.
    pub frame: u64,
    /// Total ticks processed.
    pub tick: u64,
    /// Quantum cull radius in meters.
    pub quantum_cull_radius: f32,
    /// Accumulated elapsed time in seconds.
    pub elapsed_time: f32,
    /// DreamGate — high-throughput Weave validation and dispatch.
    pub gate: Option<DreamGate>,
    /// LoomLimiter — per-frame mutation rate limiting.
    pub limiter: Option<LoomLimiter>,
    /// LoomBudgeter — hardware-derived resource budgets.
    pub budgeter: Option<LoomBudgeter>,
    /// LedgerLane receiver for cold-path draining.
    pub ledger_rx: Option<LedgerLaneReceiver>,
    /// CausalObserverLane receiver for GPU frame cold-path draining.
    pub causal_observer_rx: Option<CausalObserverLaneReceiver>,
    /// CausalObserverLane sender (stored here for wiring to renderer).
    pub causal_observer_tx: Option<dreamwell_fabric::CausalObserverLaneSender>,
    /// Active topology layer index (0-9).
    pub active_zone_index: usize,
    /// Metaphor profile for the bridge evaluator.
    pub metaphor_profile: dreamwell_metaphors::MetaphorProfile,
    /// Active particle count (decremented by POI siphon, regenerated over time).
    pub active_particle_count: f32,
    /// Form coherence target: 1.0=Cohere (fibonacci), 0.0=Wave (sinusoidal). TAB cycles.
    pub coherence_target: f32,
    /// Current coherence — smooth-lerped toward target (0.5s transition).
    pub coherence_current: f32,
    /// Gather mode active (Ctrl held).
    pub gather_active: bool,
    /// Primary action emit strength [0,1].
    pub emit_strength: f32,
    /// Universe connection: snapshot receiver (from QuantumServer).
    pub universe_snapshot_rx: Option<crossbeam_channel::Receiver<dreamwell_universe::FieldSnapshot>>,
    /// Universe connection: update sender (to QuantumServer).
    pub universe_update_tx: Option<crossbeam_channel::Sender<dreamwell_universe::ClientUpdate>>,
    /// Universe client ID.
    pub universe_client_id: u64,
    /// Whether universe is connected.
    pub universe_connected: bool,
}

impl SimulationService {
    /// Default quantum cull radius: 9.14m (30ft).
    pub const DEFAULT_QUANTUM_CULL_RADIUS: f32 = 9.14;

    /// Create a new simulation service.
    pub fn new(scene_name: &str, mode: SimulationMode) -> Self {
        Self {
            scene: GameObjectScene::new(scene_name.into()),
            kernel: None,
            encoder: None,
            bridge: None,
            last_bridge_packet: None,
            decoherence: None,
            oracle: None,
            decoherence_fields: Vec::new(),
            last_result: None,
            last_descriptor: None,
            player_object_id: 0,
            particle_offsets: Vec::new(),
            observer: SuperpositionObserver::new([0.0; 3], Self::DEFAULT_QUANTUM_CULL_RADIUS),
            journal: Vec::new(),
            console: Vec::new(),
            mode,
            readiness: RuntimeReadiness::Pending,
            frame: 0,
            tick: 0,
            quantum_cull_radius: Self::DEFAULT_QUANTUM_CULL_RADIUS,
            elapsed_time: 0.0,
            gate: None,
            limiter: None,
            budgeter: None,
            ledger_rx: None,
            causal_observer_rx: None,
            causal_observer_tx: None,
            active_zone_index: 9,
            metaphor_profile: dreamwell_metaphors::MetaphorProfile::wave(),
            active_particle_count: dreamwell_metaphors::DEFAULT_PARTICLE_COUNT as f32,
            coherence_target: 1.0,
            coherence_current: 1.0,
            gather_active: false,
            emit_strength: 0.0,
            universe_snapshot_rx: None,
            universe_update_tx: None,
            universe_client_id: 0,
            universe_connected: false,
        }
    }

    /// Whether input is enabled. Requires encoder (authoritative pipeline).
    pub fn input_enabled(&self) -> bool {
        self.readiness == RuntimeReadiness::Ready && self.encoder.is_some()
    }

    /// Connect to a universe server (spawns background kernel thread).
    /// Returns the shutdown sender so the caller can stop the universe.
    pub fn connect_universe(&mut self) -> crossbeam_channel::Sender<()> {
        let config = dreamwell_universe::UniverseConfig::default();
        let (shutdown_tx, shutdown_rx) = crossbeam_channel::bounded(1);

        // Create the field and connection protocol on the main thread,
        // then move the kernel to a background thread.
        let mut field = dreamwell_universe::QuantumField::new(&config);
        let mut connections = dreamwell_universe::ConnectionProtocol::new(config.max_clients);

        // Connect this client on layer 9 (Point — default play layer).
        let (client_id, snapshot_rx, update_tx) = connections
            .connect(&mut field, 9)
            .expect("Failed to connect to universe");

        self.universe_snapshot_rx = Some(snapshot_rx);
        self.universe_update_tx = Some(update_tx);
        self.universe_client_id = client_id;
        self.universe_connected = true;

        log::info!("Connected to universe on layer 9 (client_id={})", client_id);

        // Spawn the universe kernel in a background thread.
        let config_clone = config.clone();
        std::thread::Builder::new()
            .name("dreamwell-universe".into())
            .spawn(move || {
                let mut kernel = dreamwell_universe::UniverseKernel {
                    config: config_clone.clone(),
                    field,
                    connections,
                    metrics: dreamwell_universe::metrics::UniverseMetrics::new(),
                    shutdown_rx,
                };
                // Expose the fields that were moved
                kernel.run();
            })
            .expect("Failed to spawn universe thread");

        shutdown_tx
    }

    /// Set form coherence target. 1.0=Cohere, 0.0=Wave.
    pub fn set_coherence_target(&mut self, t: f32) {
        self.coherence_target = t.clamp(0.0, 1.0);
    }

    /// Set gather mode.
    pub fn set_gather(&mut self, active: bool) {
        self.gather_active = active;
    }

    /// Set primary action emit strength.
    pub fn set_emit_strength(&mut self, s: f32) {
        self.emit_strength = s.clamp(0.0, 1.0);
    }

    /// Initialize the simulation from a scene and spawn position.
    /// Runs the 7-step initialization sequence with CausalComputeKernel + SDK Decoherence.
    ///
    /// Returns Ok(()) if all steps pass, Err with failure description.
    pub fn initialize(
        &mut self,
        scene: GameObjectScene,
        spawn_pos: [f32; 3],
        particle_count: u32,
    ) -> Result<(), String> {
        // Step 1: Mount Braid
        self.scene = scene;
        self.journal.push(SimulationJournalEntry {
            frame: 0,
            kind: "mount_braid".into(),
            detail: format!("scene: {}, objects: {}", self.scene.name, self.scene.objects.len()),
        });
        self.console.push(format!(
            "[Info] Braid mounted from Chronoshift checkpoint (tick: {}).",
            self.tick,
        ));

        // Step 2: Reality check
        if self.scene.objects.is_empty() {
            self.readiness = RuntimeReadiness::Failed;
            return Err("reality_check: empty scene".into());
        }
        self.console.push("[Info] Reality check: all phases passed.".into());

        // Step 3: Scene instantiation
        let obj_count = self.scene.objects.len();
        self.console
            .push(format!("[Info] Scene instantiated: {obj_count} objects."));

        // Step 4: CausalComputeKernel + SuperBodyController + Encoder + Bridge + SDK Decoherence init
        let kernel = CausalComputeKernel::new(spawn_pos, particle_count);
        self.kernel = Some(kernel);
        self.encoder = Some(CausalEngineEncoder::new(spawn_pos, particle_count, 42));
        let mut bridge = QuantumBridge::new(particle_count);
        bridge.set_metaphor_profile(self.metaphor_profile.clone());
        self.bridge = Some(bridge);

        let decoherence = Decoherence::with_config(DecoherenceConfig {
            input_mode: DecoherenceInputMode::Particle,
            ..DecoherenceConfig::default()
        });
        self.decoherence = Some(decoherence);

        let mut oracle = Oracle::new(OracleConfig::default());
        let (tx, rx) = ledger_lane_channel();
        oracle.connect_ledger(tx);
        oracle.begin_frame(0);
        self.oracle = Some(oracle);
        self.ledger_rx = Some(rx);

        // CausalObserverLane channel for GPU cold path.
        let (causal_observer_tx, causal_observer_rx) = causal_observer_lane_channel();
        self.causal_observer_tx = Some(causal_observer_tx);
        self.causal_observer_rx = Some(causal_observer_rx);

        // DreamGate pipeline: Budgeter → Limiter → Gate.
        let hw = dreamwell_sdk::loom_budgeter::HardwareProfile::mid_range();
        let budgeter = LoomBudgeter::from_hardware(hw);
        let mut limiter = LoomLimiter::default();
        budgeter.apply_to_limiter(&mut limiter);
        let gate = DreamGate::new(GateConfig::from_services(&limiter, &budgeter));
        self.gate = Some(gate);
        self.limiter = Some(limiter);
        self.budgeter = Some(budgeter);

        self.particle_offsets = particle_sphere_offsets(particle_count);

        // Find player object ID and starting topology layer.
        self.player_object_id = self
            .scene
            .objects
            .iter()
            .find(|o| {
                o.property_tags
                    .iter()
                    .any(|t| t == "isInputReceiver" || t == "isPlayer")
            })
            .map(|o| o.id)
            .unwrap_or(1);

        let starting_layer = self
            .scene
            .objects
            .iter()
            .filter(|o| o.property_tags.iter().any(|t| t == "isInputReceiver"))
            .flat_map(|o| o.property_tags.iter())
            .find_map(|t| {
                t.strip_prefix("isStartingOnTopologyLayer")
                    .and_then(|v| v.parse::<u8>().ok())
            })
            .unwrap_or(9);
        if let Some(ref mut k) = self.kernel {
            k.active_topology_layer = starting_layer;
        }
        if let Some(ref mut enc) = self.encoder {
            enc.kernel_mut().active_topology_layer = starting_layer;
        }
        self.active_zone_index = starting_layer as usize;

        self.observer.position = spawn_pos;
        self.observer.active_radius = self.quantum_cull_radius;
        self.console.push(format!(
            "[Info] CausalComputeKernel mounted at [{:.1}, {:.1}, {:.1}] ({particle_count} particles).",
            spawn_pos[0], spawn_pos[1], spawn_pos[2],
        ));
        self.journal.push(SimulationJournalEntry {
            frame: 0,
            kind: "avatar_init".into(),
            detail: format!("particles: {particle_count}, pos: {spawn_pos:?}, sdk: active"),
        });

        // Step 5: GPU sync (headless: no-op)
        self.console.push("[Info] GPU resources synced.".into());

        // Step 6: Stitch
        if self.encoder.is_none() || self.scene.objects.is_empty() {
            self.readiness = RuntimeReadiness::Failed;
            return Err("stitch: render graph validation failed".into());
        }
        self.readiness = RuntimeReadiness::Syncing;
        self.console
            .push("[Info] Stitch passed: render graph validated.".into());

        // Step 7: First frame confirmation
        self.readiness = RuntimeReadiness::Ready;
        self.console
            .push("[Info] Seer is happy, reality rendered without concern.".into());
        self.console
            .push("[Info] Input controls attached to CausalComputeKernel.".into());
        self.console.push(format!(
            "[Info] Quantum pipeline: {} particles, density matrix 5×5, adaptive Hamiltonian (Model 1).",
            particle_count,
        ));
        self.console
            .push("[Info] Couplings will adapt to movement patterns via parameter shift gradient.".into());
        log::info!(
            "Quantum locomotion active: {} particles, F(12)={}, adaptive Hamiltonian learning enabled",
            particle_count,
            particle_count == 144,
        );

        // Step 7c: Connect to universe (persistent quantum field server).
        // Spawns the CausalSimulationKernel in a background thread at φ-scaled 1618Hz.
        let _universe_shutdown = self.connect_universe();
        self.console
            .push("[Info] Universe connected: persistent quantum field at 1618Hz (φ-scaled).".into());

        // Step 7b: Dispatch session begin weave through SDK pipeline.
        if let (Some(ref decoherence), Some(ref mut gate)) = (&self.decoherence, &mut self.gate) {
            let weave = decoherence.build_session_begin_weave(0);
            gate.submit(weave, 100);
        }

        Ok(())
    }

    /// Process one simulation tick via single-encoder authority pipeline.
    ///
    /// Round trip (THE_BRAIDED_PATH):
    /// (1) Build Input Weave → submit to DreamGate
    /// (2) Encoder tick (single authority: Encoder → SuperBody → Kernel → AttentionSolver)
    /// (3) Build Observation + Locomotion Weaves → submit to DreamGate
    /// (4) Gate dispatch: spindle → SacredPath → scene
    /// (5) Bridge: encode → GPU-ready BridgePacket (DreamMemory + SacredSeal)
    ///
    /// Returns the KernelResult, or None if input is not enabled.
    pub fn tick(&mut self, packet: &InputPacket) -> Option<KernelResult> {
        if !self.input_enabled() {
            return None;
        }

        self.frame += 1;
        self.tick += 1;
        self.elapsed_time += packet.dt;

        // Exponential coherence lerp toward target. Rate 6.0 ≈ 0.4s to 95% settle.
        // Frame-rate independent: identical at 30/60/144fps.
        let coherence_rate = 6.0_f32;
        let coherence_t = 1.0 - (-coherence_rate * packet.dt).exp();
        self.coherence_current += (self.coherence_target - self.coherence_current) * coherence_t;

        let gate = self.gate.as_mut()?;
        let tick = self.tick;

        gate.begin_frame(tick);
        if let Some(ref mut limiter) = self.limiter {
            limiter.begin_frame(tick);
        }

        // (1) Build Input Weave → submit to DreamGate
        if let Some(ref mut decoherence) = self.decoherence {
            let actions = packet.actions_as_u8();
            let movement = packet.movement;
            let look = [packet.camera_yaw, 0.0];
            let input_weave = decoherence.build_input_weave(tick, actions, movement, look, 0.0);
            gate.submit(input_weave, 100);
        }

        // (2) SINGLE encoder tick — authoritative quantum evolution.
        // Patch authoritative state onto packet before encoding:
        //   grounded:         from encoder kernel (previous frame's physics result)
        //   timestamp:        from elapsed_time (just incremented above)
        //   coherence_target: from coherence_current (just lerped above — NOT the raw target)
        let encoder = self.encoder.as_mut()?;
        let mut enc_packet = packet.clone();
        enc_packet.grounded = encoder.kernel().grounded;
        enc_packet.timestamp = self.elapsed_time as f64;
        enc_packet.coherence_target = self.coherence_current;
        let encode_result = encoder.encode_frame(&enc_packet, &self.decoherence_fields);

        // ── Model 1: Adaptive Hamiltonian (online gradient learning) ──
        // Every other frame, compute parameter shift gradient of free energy w.r.t.
        // Hamiltonian couplings and update them. Adapts locomotion feel to the
        // player's movement patterns in real time. Cost: ~14µs (0.085% budget).
        if self.frame % 2 == 0 {
            let kernel = encoder.kernel_mut();
            let bias = kernel.quantum.hamiltonian.bias;
            let couplings = kernel.quantum.hamiltonian.couplings;
            // Reconstruct input bias from kernel movement state.
            let moving = kernel.velocity[0].abs() > 0.01 || kernel.velocity[2].abs() > 0.01;
            let sprinting = enc_packet.sprint && moving;
            let input_bias = [
                if !moving { 2.0 } else { 0.0 },
                if moving && !sprinting { 2.0 } else { 0.0 },
                if enc_packet.jump { 3.0 } else { 0.0 },
                if kernel.landing_timer > 0.0 { 2.0 } else { 0.0 },
                if sprinting { 2.0 } else { 0.0 },
            ];
            let shift = std::f32::consts::FRAC_PI_2;
            let lr = 0.005_f32;

            let mut new_couplings = couplings;
            for k in 0..5 {
                let mut c_plus = couplings;
                c_plus[k] = (c_plus[k] + shift).min(2.0);
                let f_plus = kernel.quantum.rho.free_energy(&bias, &input_bias, &c_plus);

                let mut c_minus = couplings;
                c_minus[k] = (c_minus[k] - shift).max(0.1);
                let f_minus = kernel.quantum.rho.free_energy(&bias, &input_bias, &c_minus);

                let grad = (f_plus - f_minus) / 2.0;
                // Descend — minimize free energy for stability (not maximize).
                new_couplings[k] = (new_couplings[k] - lr * grad).clamp(0.1, 2.0);
            }
            kernel.quantum.hamiltonian.couplings = new_couplings;

            if self.frame % 120 == 0 {
                log::info!(
                    "Adaptive Hamiltonian: couplings=[{:.3}, {:.3}, {:.3}, {:.3}, {:.3}] F={:.4}",
                    new_couplings[0],
                    new_couplings[1],
                    new_couplings[2],
                    new_couplings[3],
                    new_couplings[4],
                    kernel.quantum.rho.free_energy(&bias, &input_bias, &new_couplings),
                );
            }
        }

        // Extract authoritative result from encoder (single source of truth).
        // (Universe coupling happens below, after mutable encoder borrow is released.)
        let pos = encode_result.kernel_result.position;

        // Sync standalone kernel for collision/POI checks.
        if let Some(ref mut k) = self.kernel {
            k.position = pos;
            k.velocity = encoder.kernel().velocity;
            k.grounded = encoder.kernel().grounded;
            k.facing_yaw = encoder.kernel().facing_yaw;
        }

        // (3) Observation + Locomotion Weaves → submit to DreamGate
        if let Some(ref mut decoherence) = self.decoherence {
            let facing_yaw = encoder.kernel().facing_yaw;
            let obs_weave = decoherence.build_observe_weave(tick, pos, facing_yaw);
            gate.submit(obs_weave, 100);

            // Locomotion Weave if mode changed
            if let Some(ref prev) = self.last_result {
                if encode_result.kernel_result.locomotion_mode != prev.locomotion_mode {
                    let loco_state = match encode_result.kernel_result.locomotion_mode {
                        0 => dreamwell_sdk::decohere::LocomotionState::Idle,
                        1 => dreamwell_sdk::decohere::LocomotionState::Walking,
                        2 => dreamwell_sdk::decohere::LocomotionState::Running,
                        3 => dreamwell_sdk::decohere::LocomotionState::Jumping,
                        4 => dreamwell_sdk::decohere::LocomotionState::Falling,
                        _ => dreamwell_sdk::decohere::LocomotionState::Idle,
                    };
                    let loco_weave = decoherence.build_locomotion_weave(tick, loco_state);
                    gate.submit(loco_weave, 90);
                }
            }

            // Topology transition if layer changed
            if encode_result.kernel_result.layer_changed {
                self.active_zone_index = encode_result.kernel_result.topology_layer as usize;
            }
        }

        // (4) Gate dispatch: spindle → SacredPath → scene
        if let Some(ref mut oracle) = self.oracle {
            let (_accepted, _rejected, _mutations) = gate.dispatch_through_oracle(oracle, &mut self.scene);
            oracle.end_frame();
            oracle.begin_frame(self.tick);
        }

        // (4b) Drain GPU causal observer lane → forward to Oracle's ledger for QuantumCloud archival.
        if let Some(ref causal_observer_rx) = self.causal_observer_rx {
            let gpu_events = causal_observer_rx.drain();
            if !gpu_events.is_empty() {
                log::trace!("causal_observer_lane: drained {} GPU frame events", gpu_events.len());
            }
        }

        // (5) Bridge: encode → GPU-ready packets (validates + seals + captures to DreamMemory).
        // Evaluate TagInfluenceFrame from scene POIs before bridging.
        let tag_frame = self.evaluate_tag_influences(pos);
        if let Some(ref mut bridge) = self.bridge {
            bridge.set_tag_frame(tag_frame);
            let (bp, _validation) = bridge.bridge(&encode_result, packet.dt, self.elapsed_time);
            self.last_bridge_packet = Some(bp);
        }

        // (5b) Particle siphon + regeneration based on POI proximity.
        self.update_particle_siphon(pos, packet.dt);

        // Update observer + store lightweight snapshot for next-frame locomotion comparison.
        // Only the locomotion_mode is consumed (line 381). Avoid cloning String/Vec per frame.
        self.observer.position = pos;
        let result = encode_result.kernel_result;

        self.last_result = Some(KernelResult {
            position: result.position,
            locomotion_mode: result.locomotion_mode,
            form: result.form,
            coherence: result.coherence,
            populations: result.populations,
            entropy: result.entropy,
            purity: result.purity,
            active_clip: String::new(),
            moved: result.moved,
            coalesce_events: Vec::new(),
            topology_layer: result.topology_layer,
            layer_changed: false,
        });

        // ── Universe coupling (Blaed's Algorithm: client ↔ server field) ──
        if self.universe_connected {
            // Send our state to the universe server.
            if let Some(ref tx) = self.universe_update_tx {
                if let Some(ref enc) = self.encoder {
                    let k = enc.kernel();
                    let update = dreamwell_universe::ClientUpdate {
                        client_id: self.universe_client_id,
                        populations: k.quantum.rho.populations(),
                        coherences: k.quantum.rho.off_diagonal_pairs(),
                        position: k.position,
                        layer: self.active_zone_index as u8,
                        frame: self.frame,
                    };
                    let _ = tx.try_send(update);
                }
            }
            // Receive field snapshot and apply coupling.
            if let Some(ref rx) = self.universe_snapshot_rx {
                if let Ok(snapshot) = rx.try_recv() {
                    if let Some(ref mut enc) = self.encoder {
                        let layer = self.active_zone_index;
                        let channel = &snapshot.channels[layer];
                        let coupling_eps = 0.03 * packet.dt;
                        let field_coh = channel.coherence_magnitude;
                        let rho = &mut enc.kernel_mut().quantum.rho;
                        for i in 0..5 {
                            for j in 0..5 {
                                if i != j {
                                    let retain = 1.0 - coupling_eps * (1.0 - field_coh);
                                    rho.entries[i * 5 + j] = rho.entries[i * 5 + j].scale(retain.max(0.0));
                                }
                            }
                        }
                        if self.frame % 300 == 0 {
                            log::info!(
                                "Universe sync: tick={} field_coh={:.4} field_F={:.4}",
                                snapshot.tick,
                                field_coh,
                                channel.free_energy,
                            );
                        }
                    }
                }
            }
        }

        Some(result)
    }

    /// Current authoritative position: encoder first, kernel fallback.
    fn observer_position(&self) -> Option<[f32; 3]> {
        self.encoder
            .as_ref()
            .map(|e| e.kernel().position)
            .or_else(|| self.kernel.as_ref().map(|k| k.position))
    }

    /// Check for collisions with isWall/isCollider objects within threshold.
    pub fn check_collisions(&self, threshold: f32) -> Vec<(u64, f32)> {
        let pos = match self.observer_position() {
            Some(p) => p,
            None => return Vec::new(),
        };

        self.scene
            .objects
            .iter()
            .filter_map(|o| {
                let is_collider = o.property_tags.iter().any(|t| t == "isWall" || t == "isCollider");
                if !is_collider {
                    return None;
                }
                let dx = o.transform.position[0] - pos[0];
                let dy = o.transform.position[1] - pos[1];
                let dz = o.transform.position[2] - pos[2];
                let dist = (dx * dx + dy * dy + dz * dz).sqrt();
                if dist <= threshold {
                    Some((o.id, dist))
                } else {
                    None
                }
            })
            .collect()
    }

    /// Check POI proximity. Returns Vec of (object_id, distance).
    pub fn check_poi_proximity(&self, radius: f32) -> Vec<(u64, f32)> {
        let pos = match self.observer_position() {
            Some(p) => p,
            None => return Vec::new(),
        };

        self.scene
            .objects
            .iter()
            .filter_map(|o| {
                let is_poi = o.property_tags.iter().any(|t| t == "poi" || t == "isInteractable");
                if !is_poi {
                    return None;
                }
                let dx = o.transform.position[0] - pos[0];
                let dy = o.transform.position[1] - pos[1];
                let dz = o.transform.position[2] - pos[2];
                let dist = (dx * dx + dy * dy + dz * dz).sqrt();
                if dist <= radius {
                    Some((o.id, dist))
                } else {
                    None
                }
            })
            .collect()
    }

    /// Check POI proximity and dispatch interaction weaves for nearby POIs.
    pub fn tick_poi_interactions(&mut self) {
        let pois = self.check_poi_proximity(5.0);
        if pois.is_empty() {
            return;
        }

        let gate = match &mut self.gate {
            Some(g) => g,
            None => return,
        };
        let decoherence = match &self.decoherence {
            Some(d) => d,
            None => return,
        };
        let tick = self.tick;

        for (poi_id, dist) in &pois {
            if *dist < 2.0 {
                let weave = decoherence.build_interaction_weave(tick, *poi_id);
                gate.submit(weave, 80);
            }
        }
    }

    /// Apply collision pushback from wall/collider objects.
    pub fn tick_collisions(&mut self) {
        let collisions = self.check_collisions(2.0);
        if collisions.is_empty() {
            return;
        }

        // Try encoder kernel first, fall back to direct kernel.
        let kernel = if let Some(ref mut enc) = self.encoder {
            enc.kernel_mut()
        } else if let Some(ref mut k) = self.kernel {
            k
        } else {
            return;
        };
        for (obj_id, dist) in &collisions {
            if let Some(obj) = self.scene.find(*obj_id) {
                if *dist < 0.01 {
                    continue;
                }
                let push_str = (1.0 - dist / 2.0).max(0.0) * 0.5;
                let dx = kernel.position[0] - obj.transform.position[0];
                let dz = kernel.position[2] - obj.transform.position[2];
                let len = (dx * dx + dz * dz).sqrt().max(0.001);
                kernel.position[0] += (dx / len) * push_str;
                kernel.position[2] += (dz / len) * push_str;
            }
        }
    }

    /// Evaluate TagInfluenceFrame from scene POI objects near the observer.
    /// Scans for `isPointOfInterest` tagged objects within quantum_cull_radius.
    fn evaluate_tag_influences(&self, pos: [f32; 3]) -> dreamwell_metaphors::TagInfluenceFrame {
        let mut frame = dreamwell_metaphors::TagInfluenceFrame::empty();
        let aoi_radius = self.quantum_cull_radius;

        for obj in &self.scene.objects {
            let is_poi = obj
                .property_tags
                .iter()
                .any(|t| t == "isPointOfInterest" || t == "poi" || t == "isInteractable");
            if !is_poi {
                continue;
            }

            let dx = obj.transform.position[0] - pos[0];
            let dy = obj.transform.position[1] - pos[1];
            let dz = obj.transform.position[2] - pos[2];
            let dist = (dx * dx + dy * dy + dz * dz).sqrt();
            if dist > aoi_radius {
                continue;
            }

            // Coupling strength: inverse-distance falloff, 1.0 at contact, 0.0 at radius edge.
            let coupling = (1.0 - dist / aoi_radius).max(0.0);
            let siphon_eligible = obj.property_tags.iter().any(|t| t == "isSiphon" || t == "isFractal");

            frame.poi_couplings.push(dreamwell_metaphors::PoiCoupling {
                poi_id: obj.id,
                distance: dist,
                coupling,
                siphon_eligible,
            });
        }

        // Zone biases from topology transition tags.
        for obj in &self.scene.objects {
            let is_zone = obj
                .property_tags
                .iter()
                .any(|t| t.starts_with("isTopologyTransition") || t == "isDecoherenceZone");
            if !is_zone {
                continue;
            }

            let dx = obj.transform.position[0] - pos[0];
            let dz = obj.transform.position[2] - pos[2];
            let dist = (dx * dx + dz * dz).sqrt();
            if dist > aoi_radius {
                continue;
            }

            let proximity = (1.0 - dist / aoi_radius).max(0.0);
            frame.zone_biases.push(dreamwell_metaphors::ZoneBias {
                zone_id: obj.id,
                morph_bias: proximity * 0.3,
                coherence_bias: -proximity * 0.2, // zones reduce coherence
            });
        }

        frame
    }

    /// Update particle siphon + regeneration based on POI proximity.
    /// Siphon: nearby siphon-eligible POIs reduce active_particle_count.
    /// Regeneration: particle count slowly restores to default when not siphoned.
    fn update_particle_siphon(&mut self, pos: [f32; 3], dt: f32) {
        let default_count = dreamwell_metaphors::DEFAULT_PARTICLE_COUNT as f32;
        let siphon_rate = 30.0; // particles per second per coupling unit
        let regen_rate = 10.0; // particles per second when below default

        let mut total_siphon = 0.0f32;
        for obj in &self.scene.objects {
            let is_siphon = obj.property_tags.iter().any(|t| t == "isSiphon" || t == "isFractal");
            if !is_siphon {
                continue;
            }

            let dx = obj.transform.position[0] - pos[0];
            let dy = obj.transform.position[1] - pos[1];
            let dz = obj.transform.position[2] - pos[2];
            let dist = (dx * dx + dy * dy + dz * dz).sqrt();
            let coupling = (1.0 - dist / self.quantum_cull_radius).max(0.0);
            if coupling > 0.1 {
                total_siphon += coupling;
            }
        }

        if total_siphon > 0.0 {
            self.active_particle_count -= siphon_rate * total_siphon * dt;
        } else if self.active_particle_count < default_count {
            self.active_particle_count += regen_rate * dt;
        }

        // Clamp to valid range.
        self.active_particle_count = self.active_particle_count.clamp(16.0, default_count);
    }

    /// Set the active metaphor profile and propagate to the bridge evaluator.
    pub fn set_metaphor_profile(&mut self, profile: dreamwell_metaphors::MetaphorProfile) {
        self.metaphor_profile = profile.clone();
        if let Some(ref mut bridge) = self.bridge {
            bridge.set_metaphor_profile(profile);
        }
    }

    /// Cycle to the next metaphor profile (Wave → Fibonacci → Stream → Wave).
    /// Returns the name of the newly active profile.
    pub fn cycle_metaphor(&mut self) -> &'static str {
        let new = dreamwell_metaphors::cycle_next(self.metaphor_profile.name);
        let name = new.name;
        self.set_metaphor_profile(new);
        name
    }

    /// End the simulation session.
    pub fn end_session(&mut self) {
        // Dispatch session end weave before teardown.
        if let (Some(ref decoherence), Some(ref mut oracle), Some(ref mut gate)) =
            (&self.decoherence, &mut self.oracle, &mut self.gate)
        {
            let weave = decoherence.build_session_end_weave(self.tick);
            gate.submit(weave, 100);
            let _ = gate.dispatch_through_oracle(oracle, &mut self.scene);
        }

        self.readiness = RuntimeReadiness::Pending;
        self.kernel = None;
        self.encoder = None;
        self.bridge = None;
        self.last_bridge_packet = None;
        self.decoherence = None;
        self.oracle = None;
        self.causal_observer_rx = None;
        self.causal_observer_tx = None;
        self.decoherence_fields.clear();
        self.last_result = None;
        self.last_descriptor = None;
        self.console.push("[Info] Client closing.. Chronoshift success.".into());
        self.console
            .push("[Info] Reality checked and loaded. Editor session restored.".into());
        self.journal.push(SimulationJournalEntry {
            frame: self.frame,
            kind: "end_session".into(),
            detail: "play".into(),
        });
    }
}

// ── Tests ─────────────────────────────────────────────────────────────

#[cfg(test)]
mod tests {
    use super::*;

    fn test_scene() -> GameObjectScene {
        let mut s = GameObjectScene::new("test".into());
        s.spawn("Avatar Start".into()).unwrap();
        s.objects[0].property_tags.push("isPlayer".into());
        s.objects[0].property_tags.push("isInputReceiver".into());
        s.objects[0].transform.position = [0.0, 0.5, 0.0];
        s.spawn("Ground".into()).unwrap();
        s.objects[1].property_tags.push("isStatic".into());
        s.objects[1].property_tags.push("isGround".into());
        s
    }

    #[test]
    fn simulation_new() {
        let sim = SimulationService::new("test", SimulationMode::Preview);
        assert_eq!(sim.readiness, RuntimeReadiness::Pending);
        assert!(!sim.input_enabled());
    }

    #[test]
    fn simulation_initialize_7_steps() {
        let mut sim = SimulationService::new("test", SimulationMode::Preview);
        let scene = test_scene();
        let result = sim.initialize(scene, [0.0, 0.5, 0.0], 128);
        assert!(result.is_ok(), "init should succeed: {:?}", result.err());
        assert_eq!(sim.readiness, RuntimeReadiness::Ready);
        assert!(sim.input_enabled());
        assert!(sim.kernel.is_some());
        assert!(sim.encoder.is_some());
        assert!(sim.bridge.is_some());
        assert!(sim.decoherence.is_some());
        assert!(sim.oracle.is_some());
        assert!(sim.console.iter().any(|m| m.contains("Seer is happy")));
        assert!(sim.console.iter().any(|m| m.contains("CausalComputeKernel")));
    }

    #[test]
    fn simulation_input_gated_before_ready() {
        let mut sim = SimulationService::new("test", SimulationMode::Preview);
        let packet = InputPacket {
            movement: [0.0, 1.0],
            ..InputPacket::idle(1.0 / 60.0, 0)
        };
        let result = sim.tick(&packet);
        assert!(result.is_none(), "input should be gated before init");
    }

    #[test]
    fn simulation_tick_moves_player() {
        let mut sim = SimulationService::new("test", SimulationMode::Preview);
        sim.initialize(test_scene(), [0.0, 0.5, 0.0], 128).unwrap();
        let packet = InputPacket {
            movement: [0.0, 1.0],
            ..InputPacket::idle(1.0 / 60.0, 1)
        };
        let result = sim.tick(&packet);
        assert!(result.is_some());
        let r = result.unwrap();
        assert!(r.position != [0.0, 0.5, 0.0], "player should move after forward input");
    }

    #[test]
    fn simulation_collision_detection() {
        let mut sim = SimulationService::new("test", SimulationMode::Preview);
        let mut scene = test_scene();
        scene.spawn("Wall".into()).unwrap();
        let wall_idx = scene.objects.len() - 1;
        scene.objects[wall_idx].property_tags.push("isWall".into());
        scene.objects[wall_idx].property_tags.push("isCollider".into());
        scene.objects[wall_idx].transform.position = [0.5, 0.5, 0.0];
        sim.initialize(scene, [0.0, 0.5, 0.0], 128).unwrap();

        let collisions = sim.check_collisions(1.0);
        assert!(!collisions.is_empty());
    }

    #[test]
    fn simulation_poi_proximity() {
        let mut sim = SimulationService::new("test", SimulationMode::Preview);
        let mut scene = test_scene();
        scene.spawn("POI".into()).unwrap();
        let poi_idx = scene.objects.len() - 1;
        scene.objects[poi_idx].property_tags.push("isInteractable".into());
        scene.objects[poi_idx].transform.position = [0.0, 0.5, -1.0];
        sim.initialize(scene, [0.0, 0.5, 0.0], 128).unwrap();

        let pois = sim.check_poi_proximity(2.0);
        assert!(!pois.is_empty());
    }

    #[test]
    fn simulation_end_session() {
        let mut sim = SimulationService::new("test", SimulationMode::Preview);
        sim.initialize(test_scene(), [0.0, 0.5, 0.0], 128).unwrap();
        sim.end_session();
        assert_eq!(sim.readiness, RuntimeReadiness::Pending);
        assert!(!sim.input_enabled());
        assert!(sim.kernel.is_none());
        assert!(sim.encoder.is_none());
        assert!(sim.bridge.is_none());
        assert!(sim.decoherence.is_none());
        assert!(sim.oracle.is_none());
        assert!(sim.console.iter().any(|m| m.contains("Chronoshift success")));
    }

    #[test]
    fn simulation_empty_scene_fails() {
        let mut sim = SimulationService::new("test", SimulationMode::Preview);
        let scene = GameObjectScene::new("empty".into());
        let result = sim.initialize(scene, [0.0; 3], 128);
        assert!(result.is_err());
        assert_eq!(sim.readiness, RuntimeReadiness::Failed);
    }

    #[test]
    fn simulation_mode_variants() {
        assert_ne!(SimulationMode::Preview, SimulationMode::Published);
    }

    #[test]
    fn cycle_metaphor_changes_profile() {
        let mut sim = SimulationService::new("test", SimulationMode::Preview);
        sim.initialize(test_scene(), [0.0, 0.5, 0.0], 128).unwrap();
        assert_eq!(sim.metaphor_profile.name, "wave");
        let name = sim.cycle_metaphor();
        assert_eq!(name, "keynote_fibonacci");
        assert_eq!(sim.metaphor_profile.name, "keynote_fibonacci");
        let name = sim.cycle_metaphor();
        assert_eq!(name, "cohered_stream");
        let name = sim.cycle_metaphor();
        assert_eq!(name, "wave");
    }

    #[test]
    fn default_profile_is_wave() {
        let sim = SimulationService::new("test", SimulationMode::Preview);
        assert_eq!(sim.metaphor_profile.name, "wave");
    }

    #[test]
    fn simulation_quantum_cull_radius() {
        let sim = SimulationService::new("test", SimulationMode::Preview);
        assert!((sim.quantum_cull_radius - SimulationService::DEFAULT_QUANTUM_CULL_RADIUS).abs() < 0.01);
    }

    #[test]
    fn simulation_observer_position_updates() {
        let mut sim = SimulationService::new("test", SimulationMode::Preview);
        sim.initialize(test_scene(), [0.0, 0.5, 0.0], 128).unwrap();
        let packet = InputPacket {
            movement: [0.0, 1.0],
            ..InputPacket::idle(1.0, 1)
        };
        sim.tick(&packet);
        assert!(
            sim.observer.position != [0.0, 0.5, 0.0],
            "observer should follow kernel position"
        );
    }

    #[test]
    fn simulation_journal_records_lifecycle() {
        let mut sim = SimulationService::new("test", SimulationMode::Preview);
        sim.initialize(test_scene(), [0.0, 0.5, 0.0], 128).unwrap();
        assert!(sim.journal.iter().any(|e| e.kind == "mount_braid"));
        assert!(sim.journal.iter().any(|e| e.kind == "avatar_init"));
        sim.end_session();
        assert!(sim.journal.iter().any(|e| e.kind == "end_session"));
    }
}