mago-analyzer 1.47.1

//! Worker-backed analyzer plugins.

use std::borrow::Cow;
use std::collections::HashMap;
use std::collections::HashSet;
use std::sync::Arc;
use std::sync::Mutex;
use std::sync::OnceLock;
use std::sync::atomic::AtomicU64;
use std::sync::atomic::Ordering;
use std::thread::JoinHandle;
use std::time::Duration;
use std::time::Instant;

use crate::plugin::provider::assertion::InvocationAssertions;
use mago_codex::metadata::CodebaseMetadata;
use mago_codex::metadata::class_like::ClassLikeMetadata;
use mago_codex::reference::SymbolReferences;
use mago_codex::ttype::union::TUnion;
use mago_database::file::File;
use mago_database::file::FileId;
use mago_database::file::FileType;
use mago_extension::Frame;
use mago_extension::WorkerError;
use mago_extension::WorkerPool;
use mago_extension::WorkerRequestHandler;
use mago_names::ResolvedNames;
use mago_php_version::PHPVersion;
use mago_reporting::IssueCollection;
use mago_span::Span;
use mago_syntax::cst::NodeKind;
use mago_syntax::cst::Program;
use mago_word::Word;
use mago_word::WordMap;
use mago_word::WordSet;
use mago_word::ascii_lowercase_word;
use mago_word::concat_word;
use mago_word::starts_with_ignore_case;

use crate::artifacts::AnalysisArtifacts;
use crate::invocation::EffectiveCallableSignature;
use crate::invocation::Invocation;
use crate::plugin::available_plugins;

pub use error::ExternalAnalyzerError;
pub use lifecycle::AFTER_FILE_ANALYSIS_BATCH_SIZE;
pub use lifecycle::FileAnalysisSnapshot;
use protocol::Registration;

mod error;
mod lifecycle;
mod metadata;
pub mod protocol;
mod scan;

pub use scan::CodebaseScanFile;
pub use scan::CodebaseScanPlan;

const SLOW_PROVIDER_THRESHOLD: Duration = Duration::from_millis(5);
const SLOW_LIFECYCLE_THRESHOLD: Duration = Duration::from_millis(5);
const MAXIMUM_PROVIDER_RESPONSE_CACHE_ENTRIES: usize = 0x0001_0000;
const PROVIDER_CALLABLE_SIGNATURE: u8 = 1;
const PROVIDER_OVERRIDES_DECLARED_SIGNATURE: u8 = 1 << 1;
const PROVIDER_UNDECLARED_RETURN_TYPE_ONLY: u8 = 1 << 2;
const PROVIDER_MEMOIZED: u8 = 1 << 3;
static NEXT_ANALYSIS_GENERATION: AtomicU64 = AtomicU64::new(1);

type ExternalAnalyzerResult<T> = Result<T, Arc<ExternalAnalyzerError>>;

#[derive(Debug, Default)]
pub struct BeforeAnalysisResult {
    pub issues: IssueCollection,
    pub references: SymbolReferences,
}

#[derive(Debug, Default)]
pub struct AfterFileAnalysisResult {
    pub issues: IssueCollection,
    pub references_by_file: foldhash::HashMap<FileId, SymbolReferences>,
}

fn extend_references_by_file(
    target: &mut foldhash::HashMap<FileId, SymbolReferences>,
    source: impl IntoIterator<Item = (FileId, SymbolReferences)>,
) {
    for (file_id, references) in source {
        target.entry(file_id).or_default().extend(references);
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum PropertyAccessKind {
    Read,
    Write,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub(crate) struct EffectivePropertyType {
    pub read_type: Option<TUnion>,
    pub write_type: Option<TUnion>,
}

/// Immutable request context shared by every external hook in one analysis run.
///
/// A new session is created for every frozen codebase generation. Keeping the
/// generation on the request, instead of on the worker pool, makes PHP-side
/// metadata caches safe when a pool is reused by watch mode or by concurrent
/// analysis services.
#[derive(Debug)]
pub struct ExternalAnalysisSession {
    generation: u64,
    sources: foldhash::HashMap<FileId, Arc<File>>,
}

impl ExternalAnalysisSession {
    #[must_use]
    pub fn from_files(files: impl IntoIterator<Item = Arc<File>>) -> Self {
        let generation = NEXT_ANALYSIS_GENERATION.fetch_add(1, Ordering::Relaxed);
        let sources = files.into_iter().map(|file| (file.id, file)).collect();

        Self { generation, sources }
    }

    #[inline]
    #[must_use]
    pub(crate) const fn generation(&self) -> u64 {
        self.generation
    }

    #[inline]
    #[must_use]
    pub(crate) fn source_name(&self, file_id: FileId) -> Option<&[u8]> {
        self.sources.get(&file_id).map(|file| file.name.as_ref())
    }

    fn source(&self, name: &[u8]) -> Option<(FileId, u32)> {
        self.sources.iter().find_map(|(file_id, file)| (file.name.as_ref() == name).then_some((*file_id, file.size)))
    }

    fn source_file(&self, file_id: FileId) -> Option<&File> {
        self.sources.get(&file_id).map(AsRef::as_ref)
    }
}

#[derive(Debug, Default)]
struct ExternalAnalyzerTelemetry {
    function_lookups: AtomicU64,
    method_lookups: AtomicU64,
    property_lookups: AtomicU64,
    property_initialization_lookups: AtomicU64,
    class_initializer_lookups: AtomicU64,
    issue_filter_batches: AtomicU64,
    issue_filter_candidates: AtomicU64,
    issue_filter_removed: AtomicU64,
    issue_filter_errors: AtomicU64,
    issue_filter_request_bytes: AtomicU64,
    issue_filter_response_bytes: AtomicU64,
    signature_lookups: AtomicU64,
    assertion_lookups: AtomicU64,
    backend_checks: AtomicU64,
    candidate_providers: AtomicU64,
    matched_providers: AtomicU64,
    unmatched_lookups: AtomicU64,
    requests: AtomicU64,
    ipc_requests: AtomicU64,
    provider_cache_hits: AtomicU64,
    signature_requests: AtomicU64,
    assertion_requests: AtomicU64,
    provided_types: AtomicU64,
    initialized_properties: AtomicU64,
    provided_class_initializers: AtomicU64,
    provided_signatures: AtomicU64,
    provided_assertions: AtomicU64,
    declined_requests: AtomicU64,
    errors: AtomicU64,
    snapshotted_types: AtomicU64,
    arguments: AtomicU64,
    typed_arguments: AtomicU64,
    request_bytes: AtomicU64,
    response_bytes: AtomicU64,
    nested_requests: AtomicU64,
    nested_errors: AtomicU64,
    nested_request_bytes: AtomicU64,
    nested_response_bytes: AtomicU64,
    comparison_batches: AtomicU64,
    comparisons: AtomicU64,
    metadata_queries: AtomicU64,
    analysis_queries: AtomicU64,
    symbol_reference_queries: AtomicU64,
    before_analysis_requests: AtomicU64,
    after_file_analysis_requests: AtomicU64,
    after_file_analysis_files: AtomicU64,
    after_analysis_requests: AtomicU64,
    lifecycle_plugins: AtomicU64,
    lifecycle_issues: AtomicU64,
    lifecycle_errors: AtomicU64,
    lifecycle_request_bytes: AtomicU64,
    lifecycle_response_bytes: AtomicU64,
    matching_ns: AtomicU64,
    encode_ns: AtomicU64,
    type_snapshot_ns: AtomicU64,
    ipc_ns: AtomicU64,
    comparison_ns: AtomicU64,
    metadata_query_ns: AtomicU64,
    analysis_query_ns: AtomicU64,
    symbol_reference_query_ns: AtomicU64,
    lifecycle_encode_ns: AtomicU64,
    lifecycle_ipc_ns: AtomicU64,
    lifecycle_decode_ns: AtomicU64,
    lifecycle_ns: AtomicU64,
    issue_filter_encode_ns: AtomicU64,
    issue_filter_ipc_ns: AtomicU64,
    issue_filter_decode_ns: AtomicU64,
    issue_filter_ns: AtomicU64,
    nested_ns: AtomicU64,
    decode_ns: AtomicU64,
    lookup_ns: AtomicU64,
}

impl ExternalAnalyzerTelemetry {
    fn record_nested_request(
        &self,
        request_bytes: usize,
        elapsed: Duration,
        result: &Result<(protocol::NestedRequestKind, Vec<u8>), ExternalAnalyzerError>,
    ) {
        self.nested_requests.fetch_add(1, Ordering::Relaxed);
        self.nested_request_bytes.fetch_add(request_bytes as u64, Ordering::Relaxed);
        self.nested_ns.fetch_add(duration_nanos(elapsed), Ordering::Relaxed);

        let Ok((kind, response)) = result else {
            self.nested_errors.fetch_add(1, Ordering::Relaxed);
            self.errors.fetch_add(1, Ordering::Relaxed);
            return;
        };

        self.nested_response_bytes.fetch_add(response.len() as u64, Ordering::Relaxed);
        match kind {
            protocol::NestedRequestKind::TypeComparison => {
                self.comparisons.fetch_add(1, Ordering::Relaxed);
                self.comparison_ns.fetch_add(duration_nanos(elapsed), Ordering::Relaxed);
            }
            protocol::NestedRequestKind::TypeComparisonBatch(count) => {
                self.comparison_batches.fetch_add(1, Ordering::Relaxed);
                self.comparisons.fetch_add(*count as u64, Ordering::Relaxed);
                self.comparison_ns.fetch_add(duration_nanos(elapsed), Ordering::Relaxed);
            }
            protocol::NestedRequestKind::CodebaseQuery => {
                self.metadata_queries.fetch_add(1, Ordering::Relaxed);
                self.metadata_query_ns.fetch_add(duration_nanos(elapsed), Ordering::Relaxed);
            }
            protocol::NestedRequestKind::AnalysisQuery => {
                self.analysis_queries.fetch_add(1, Ordering::Relaxed);
                self.analysis_query_ns.fetch_add(duration_nanos(elapsed), Ordering::Relaxed);
            }
            protocol::NestedRequestKind::SymbolReferenceQuery => {
                self.symbol_reference_queries.fetch_add(1, Ordering::Relaxed);
                self.symbol_reference_query_ns.fetch_add(duration_nanos(elapsed), Ordering::Relaxed);
            }
        }
    }
}

#[derive(Clone, Copy)]
enum LifecyclePhase {
    Before,
    AfterFile,
    AfterFileBatch,
    After,
}

impl LifecyclePhase {
    const fn request_kind(self) -> u16 {
        match self {
            Self::Before => lifecycle::BEFORE_ANALYSIS_REQUEST,
            Self::AfterFile => lifecycle::AFTER_FILE_ANALYSIS_REQUEST,
            Self::AfterFileBatch => lifecycle::AFTER_FILE_ANALYSIS_BATCH_REQUEST,
            Self::After => lifecycle::AFTER_ANALYSIS_REQUEST,
        }
    }

    const fn name(self) -> &'static str {
        match self {
            Self::Before => "before-analysis",
            Self::AfterFile | Self::AfterFileBatch => "after-file-analysis",
            Self::After => "after-analysis",
        }
    }
}

struct LookupTrace<'telemetry> {
    telemetry: &'telemetry ExternalAnalyzerTelemetry,
    started_at: Instant,
}

impl Drop for LookupTrace<'_> {
    fn drop(&mut self) {
        self.telemetry.lookup_ns.fetch_add(duration_nanos(self.started_at.elapsed()), Ordering::Relaxed);
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ExternalExtension {
    pub identifier: String,
    pub name: String,
    pub version: String,
    pub plugins: Vec<ExternalPlugin>,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ExternalPlugin {
    pub index: u16,
    pub extension: String,
    pub identifier: String,
    pub name: String,
    pub description: String,
    pub aliases: Vec<String>,
    pub default_enabled: bool,
    pub initialization: bool,
    pub before_analysis: bool,
    pub after_file_analysis: bool,
    pub after_file_expression_types: bool,
    pub node_analysis: bool,
    pub after_analysis: bool,
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct ExternalStub {
    name: Vec<u8>,
    contents: Vec<u8>,
}

impl ExternalStub {
    fn new(extension: &str, plugin: &str, filename: &[u8], contents: Vec<u8>) -> Self {
        let mut name = Vec::with_capacity(18 + extension.len() + plugin.len() + filename.len());
        name.extend_from_slice(b"@mago-extension/");
        append_path_component(&mut name, extension.as_bytes());
        name.push(b'/');
        append_path_component(&mut name, plugin.as_bytes());
        name.push(b'/');
        name.extend_from_slice(filename);
        Self { name, contents }
    }

    fn to_file(&self) -> File {
        File::new(Cow::Owned(self.name.clone()), FileType::External, None, Cow::Owned(self.contents.clone()))
    }
}

impl ExternalPlugin {
    fn matches(&self, name: &str) -> bool {
        self.identifier.eq_ignore_ascii_case(name) || self.aliases.iter().any(|alias| alias.eq_ignore_ascii_case(name))
    }
}

impl Registration {
    fn file_analysis_plugins(&self) -> Vec<u16> {
        let mut plugins =
            Vec::with_capacity(self.after_file_analysis_plugins.len().saturating_add(self.node_analysis_plugins.len()));
        plugins.extend_from_slice(&self.after_file_analysis_plugins);
        plugins.extend_from_slice(&self.node_analysis_plugins);
        plugins.sort_unstable();
        plugins.dedup();
        plugins
    }

    fn file_analysis_requires_expression_types(&self, plugins: &[u16]) -> bool {
        self.plugins.iter().any(|plugin| plugins.contains(&plugin.index) && plugin.after_file_expression_types)
            || self.node_analysis_hooks.iter().any(|hook| {
                plugins.contains(&hook.plugin) && hook.requirements & NODE_REQUIREMENT_EXPRESSION_TYPES != 0
            })
            || self.method_call_analysis_hooks.iter().any(|hook| {
                plugins.contains(&hook.plugin) && hook.requirements & NODE_REQUIREMENT_EXPRESSION_TYPES != 0
            })
            || self.class_like_analysis_hooks.iter().any(|hook| {
                plugins.contains(&hook.plugin) && hook.requirements & NODE_REQUIREMENT_EXPRESSION_TYPES != 0
            })
    }

    pub(crate) fn node_analysis_requirements(&self) -> Option<NodeAnalysisRequirements> {
        let mut targets = [false; u8::MAX as usize + 1];
        let mut requirements = [0; u8::MAX as usize + 1];
        let mut any = false;
        for hook in &self.node_analysis_hooks {
            for target in &hook.targets {
                targets[*target as usize] = true;
                requirements[*target as usize] |= hook.requirements;
                any = true;
            }
        }

        let method_call_hooks: Arc<[MethodCallAnalysisHookRegistration]> =
            Arc::from(self.method_call_analysis_hooks.clone().into_boxed_slice());
        any |= !method_call_hooks.is_empty();

        let class_like_hooks: Arc<[ClassLikeAnalysisHookRegistration]> =
            Arc::from(self.class_like_analysis_hooks.clone().into_boxed_slice());
        any |= !class_like_hooks.is_empty();

        any.then_some(NodeAnalysisRequirements { targets, requirements, method_call_hooks, class_like_hooks })
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
enum FunctionTarget {
    Exact(Vec<u8>),
    Prefix(Vec<u8>),
}

impl FunctionTarget {
    fn matches(&self, name: &[u8]) -> bool {
        match self {
            Self::Exact(target) => name.eq_ignore_ascii_case(target),
            Self::Prefix(prefix) => starts_with_ignore_case(name, prefix),
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
struct MethodTarget {
    class: Vec<u8>,
    method: Vec<u8>,
}

impl MethodTarget {
    fn matches(&self, codebase: &CodebaseMetadata, class: &[u8], method: &[u8]) -> bool {
        class_pattern_matches(codebase, &self.class, class) && pattern_matches(&self.method, method)
    }
}

#[derive(Clone, Copy)]
enum CallableTarget<'target> {
    Function(&'target [u8]),
    Method { class: &'target [u8], method: &'target [u8] },
}

impl<'target> CallableTarget<'target> {
    fn affinity(self) -> &'target [u8] {
        match self {
            Self::Function(function) => function,
            Self::Method { class, .. } => class,
        }
    }
}

impl std::fmt::Display for CallableTarget<'_> {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Function(function) => mago_bytes::BytesDisplay(function).fmt(formatter),
            Self::Method { class, method } => {
                write!(formatter, "{}::{}", mago_bytes::BytesDisplay(class), mago_bytes::BytesDisplay(method))
            }
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct ProviderRegistration<T> {
    plugin: u16,
    index: u16,
    capabilities: u8,
    targets: Vec<T>,
}

type FunctionProvider = ProviderRegistration<FunctionTarget>;
type MethodProvider = ProviderRegistration<MethodTarget>;
type PropertyProvider = ProviderRegistration<PropertyTarget>;
type ClassInitializerProvider = ProviderRegistration<Vec<u8>>;
type IssueFilterHookRegistration = ProviderRegistration<String>;
type CodebaseScanHookRegistration = ProviderRegistration<String>;

#[derive(Debug, Clone, PartialEq, Eq)]
struct PropertyTarget {
    class: Vec<u8>,
    property: Vec<u8>,
}

impl PropertyTarget {
    fn matches(&self, codebase: &CodebaseMetadata, class: &[u8], property: &[u8]) -> bool {
        class_pattern_matches(codebase, &self.class, class) && property_pattern_matches(&self.property, property)
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct EntryPoint {
    plugin: u16,
    source: Word,
    target: MethodTarget,
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct AttributedEntryPoint {
    plugin: u16,
    source: Word,
    class: Vec<u8>,
    attribute: Vec<u8>,
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct AnalysisHookRegistration<T> {
    plugin: u16,
    index: u16,
    requirements: u8,
    targets: Vec<T>,
    route: u32,
}

type NodeAnalysisHookRegistration = AnalysisHookRegistration<NodeKind>;
type MethodCallAnalysisHookRegistration = AnalysisHookRegistration<MethodTarget>;
type ClassLikeAnalysisHookRegistration = AnalysisHookRegistration<Word>;

pub(super) const NODE_REQUIREMENT_EXPRESSION_TYPES: u8 = 1;
pub(super) const NODE_REQUIREMENT_TARGET_EXPRESSION_TYPES: u8 = 1 << 1;
pub(super) const NODE_REQUIREMENT_RECEIVER_TYPE: u8 = 1 << 2;
pub(super) const NODE_REQUIREMENT_ARGUMENT_TYPES: u8 = 1 << 3;
pub(super) const NODE_REQUIREMENT_TARGET_SUBTREE: u8 = 1 << 4;
pub(super) const NODE_REQUIREMENT_SOURCE_TEXT: u8 = 1 << 5;
pub(super) const NODE_REQUIREMENTS_ALL: u8 = NODE_REQUIREMENT_EXPRESSION_TYPES
    | NODE_REQUIREMENT_TARGET_EXPRESSION_TYPES
    | NODE_REQUIREMENT_RECEIVER_TYPE
    | NODE_REQUIREMENT_ARGUMENT_TYPES
    | NODE_REQUIREMENT_TARGET_SUBTREE
    | NODE_REQUIREMENT_SOURCE_TEXT;

/// Syntax targets and embedded data requested by external node-analysis hooks.
#[derive(Debug, Clone)]
pub struct NodeAnalysisRequirements {
    targets: [bool; u8::MAX as usize + 1],
    requirements: [u8; u8::MAX as usize + 1],
    method_call_hooks: Arc<[MethodCallAnalysisHookRegistration]>,
    class_like_hooks: Arc<[ClassLikeAnalysisHookRegistration]>,
}

impl NodeAnalysisRequirements {
    #[inline]
    #[must_use]
    pub(crate) const fn targets(&self) -> &[bool; u8::MAX as usize + 1] {
        &self.targets
    }

    #[inline]
    #[must_use]
    pub(crate) const fn requirements(&self, kind: NodeKind) -> u8 {
        self.requirements[kind as usize]
    }

    #[inline]
    #[must_use]
    pub(crate) fn includes_source_text(&self) -> bool {
        self.requirements.iter().any(|requirements| requirements & NODE_REQUIREMENT_SOURCE_TEXT != 0)
            || self.method_call_hooks.iter().any(|hook| hook.requirements & NODE_REQUIREMENT_SOURCE_TEXT != 0)
            || self.class_like_hooks.iter().any(|hook| hook.requirements & NODE_REQUIREMENT_SOURCE_TEXT != 0)
    }
}

type ProviderExactIndex = WordMap<Vec<u16>>;
type ProviderWildcardIndex<T> = Vec<(u16, Vec<T>)>;

enum ProviderIndices {
    One(u16),
    Multiple(Vec<u16>),
}

impl ProviderIndices {
    #[inline]
    fn from_iter(mut indices: impl Iterator<Item = u16>) -> Option<Self> {
        let first = indices.next()?;
        let Some(second) = indices.next() else {
            return Some(Self::One(first));
        };

        let mut matched = Vec::with_capacity(4);
        matched.extend([first, second]);
        matched.extend(indices);
        Some(Self::Multiple(matched))
    }

    #[inline]
    fn as_slice(&self) -> &[u16] {
        match self {
            Self::One(index) => std::slice::from_ref(index),
            Self::Multiple(indices) => indices,
        }
    }

    fn insert_sorted(&mut self, index: u16) {
        match self {
            Self::One(existing) if *existing == index => {}
            Self::One(existing) => {
                let (first, second) = if *existing < index { (*existing, index) } else { (index, *existing) };
                *self = Self::Multiple(vec![first, second]);
            }
            Self::Multiple(indices) => {
                if let Err(position) = indices.binary_search(&index) {
                    indices.insert(position, index);
                }
            }
        }
    }

    fn from_exact_and_wildcards(exact: &[u16], wildcards: impl IntoIterator<Item = u16>) -> Option<ProviderIndices> {
        Self::add_wildcards(Self::from_iter(exact.iter().copied()), wildcards)
    }

    fn add_wildcards(mut indices: Option<Self>, wildcards: impl IntoIterator<Item = u16>) -> Option<ProviderIndices> {
        for index in wildcards {
            match &mut indices {
                Some(indices) => indices.insert_sorted(index),
                None => indices = Some(Self::One(index)),
            }
        }

        indices
    }
}

/// Request transport used by worker-backed analyzer providers.
pub trait AnalyzerTransport: std::fmt::Debug + Send + Sync {
    /// Starts preparing additional transport capacity for a sustained parallel workload.
    fn prepare_capacity(self: &Arc<Self>) {}

    /// Sends initialization data to every worker process.
    ///
    /// # Errors
    ///
    /// Returns an error if a worker cannot process the request.
    fn broadcast(&self, payload: &[u8]) -> Result<Vec<Vec<u8>>, WorkerError>;

    /// Returns the largest payload accepted by this transport.
    fn maximum_payload_size(&self) -> usize {
        usize::MAX
    }

    /// Sends an ordered, replayable state-replacement sequence to every worker.
    ///
    /// # Errors
    ///
    /// Returns an error if a worker cannot process the complete sequence.
    fn broadcast_sequence(&self, _group: u64, payloads: &[Vec<u8>]) -> Result<Vec<Vec<Vec<u8>>>, WorkerError> {
        payloads.iter().map(|payload| self.broadcast(payload)).collect()
    }

    /// Sends one provider request to an available worker.
    ///
    /// # Errors
    ///
    /// Returns an error if no worker can process the request.
    fn request(&self, payload: Vec<u8>) -> Result<Vec<u8>, WorkerError>;

    /// Sends one provider request while servicing nested analyzer queries.
    ///
    /// # Errors
    ///
    /// Returns an error if the worker or nested query handler fails.
    fn request_with_handler<H>(&self, payload: Vec<u8>, handler: &mut H) -> Result<Vec<u8>, WorkerError>
    where
        H: WorkerRequestHandler;

    /// Sends a provider request with a stable process-local cache key.
    ///
    /// The default implementation preserves compatibility with transports
    /// that do not expose worker affinity.
    ///
    /// # Errors
    ///
    /// Returns an error if the worker or nested query handler fails.
    fn request_with_handler_affinity<H>(
        &self,
        payload: Vec<u8>,
        _affinity: &[u8],
        handler: &mut H,
    ) -> Result<Vec<u8>, WorkerError>
    where
        H: WorkerRequestHandler,
    {
        self.request_with_handler(payload, handler)
    }
}

impl AnalyzerTransport for WorkerPool {
    fn prepare_capacity(self: &Arc<Self>) {
        Self::prepare_capacity(self);
    }

    fn broadcast(&self, payload: &[u8]) -> Result<Vec<Vec<u8>>, WorkerError> {
        Self::broadcast(self, payload)
    }

    fn maximum_payload_size(&self) -> usize {
        Self::maximum_payload_size(self)
    }

    fn broadcast_sequence(&self, group: u64, payloads: &[Vec<u8>]) -> Result<Vec<Vec<Vec<u8>>>, WorkerError> {
        Self::broadcast_sequence(self, group, payloads)
    }

    fn request(&self, payload: Vec<u8>) -> Result<Vec<u8>, WorkerError> {
        Self::request(self, payload)
    }

    fn request_with_handler<H>(&self, payload: Vec<u8>, handler: &mut H) -> Result<Vec<u8>, WorkerError>
    where
        H: WorkerRequestHandler,
    {
        Self::request_with_handler(self, payload, handler)
    }

    fn request_with_handler_affinity<H>(
        &self,
        payload: Vec<u8>,
        affinity: &[u8],
        handler: &mut H,
    ) -> Result<Vec<u8>, WorkerError>
    where
        H: WorkerRequestHandler,
    {
        Self::request_with_handler_affinity(self, payload, affinity, handler)
    }
}

#[derive(Debug)]
struct Backend<T> {
    transport: Arc<T>,
    registration: Registration,
    provider_response_cache: Mutex<ProviderResponseCache>,
    function_capabilities: Box<[u8]>,
    method_capabilities: Box<[u8]>,
    function_assertion_capabilities: Box<[u8]>,
    method_assertion_capabilities: Box<[u8]>,
    function_exact: WordMap<Vec<u16>>,
    function_wildcard: Vec<(u16, Vec<FunctionTarget>)>,
    function_signature_exact: WordMap<Vec<u16>>,
    function_signature_wildcard: Vec<(u16, Vec<FunctionTarget>)>,
    function_assertion_exact: WordMap<Vec<u16>>,
    function_assertion_wildcard: Vec<(u16, Vec<FunctionTarget>)>,
    method_exact: WordMap<Vec<u16>>,
    method_wildcard: Vec<(u16, Vec<MethodTarget>)>,
    method_signature_exact: WordMap<Vec<u16>>,
    method_signature_wildcard: Vec<(u16, Vec<MethodTarget>)>,
    method_assertion_exact: WordMap<Vec<u16>>,
    method_assertion_wildcard: Vec<(u16, Vec<MethodTarget>)>,
    property_exact: ProviderExactIndex,
    property_wildcard: ProviderWildcardIndex<PropertyTarget>,
    property_initialization_exact: ProviderExactIndex,
    property_initialization_wildcard: ProviderWildcardIndex<PropertyTarget>,
    class_initializer_exact: ProviderExactIndex,
    class_initializer_wildcard: ProviderWildcardIndex<Vec<u8>>,
    issue_filter_indices: Box<[u16]>,
    issue_filter_codes: foldhash::HashSet<String>,
}

#[derive(Debug, Default)]
struct ProviderResponseCache {
    generation: u64,
    responses: foldhash::HashMap<Vec<u8>, Vec<u8>>,
}

impl ProviderResponseCache {
    fn get(&mut self, generation: u64, request: &[u8]) -> Option<Vec<u8>> {
        self.select_generation(generation);
        self.responses.get(request).cloned()
    }

    fn insert(&mut self, generation: u64, request: Vec<u8>, response: Vec<u8>) {
        self.select_generation(generation);
        if self.responses.len() < MAXIMUM_PROVIDER_RESPONSE_CACHE_ENTRIES {
            self.responses.insert(request, response);
        }
    }

    fn select_generation(&mut self, generation: u64) {
        if self.generation != generation {
            self.generation = generation;
            self.responses.clear();
        }
    }
}

fn provider_capabilities<T>(providers: &[ProviderRegistration<T>]) -> Box<[u8]> {
    let Some(maximum) = providers.iter().map(|provider| provider.index).max() else {
        return Box::new([]);
    };

    let mut capabilities = vec![0; usize::from(maximum) + 1];
    for provider in providers {
        capabilities[usize::from(provider.index)] = provider.capabilities;
    }

    capabilities.into_boxed_slice()
}

impl<T> Backend<T> {
    fn new(transport: Arc<T>, registration: Registration) -> Self {
        let (function_exact, function_wildcard) = index_function_providers(&registration.function_providers);
        let (function_signature_exact, function_signature_wildcard) = index_function_providers(
            registration
                .function_providers
                .iter()
                .filter(|provider| provider.capabilities & PROVIDER_CALLABLE_SIGNATURE != 0),
        );
        let (function_assertion_exact, function_assertion_wildcard) =
            index_function_providers(&registration.function_assertion_providers);
        let (method_exact, method_wildcard) = index_method_providers(&registration.method_providers);
        let (method_signature_exact, method_signature_wildcard) = index_method_providers(
            registration
                .method_providers
                .iter()
                .filter(|provider| provider.capabilities & PROVIDER_CALLABLE_SIGNATURE != 0),
        );
        let (method_assertion_exact, method_assertion_wildcard) =
            index_method_providers(&registration.method_assertion_providers);

        let (property_exact, property_wildcard) = index_property_providers(&registration.property_providers);
        let (property_initialization_exact, property_initialization_wildcard) =
            index_property_providers(&registration.property_initialization_providers);
        let (class_initializer_exact, class_initializer_wildcard) =
            index_class_providers(&registration.class_initializer_providers);
        let issue_filter_indices = registration.issue_filter_hooks.iter().map(|hook| hook.index).collect::<Box<[_]>>();
        let issue_filter_codes =
            registration.issue_filter_hooks.iter().flat_map(|hook| hook.targets.iter().cloned()).collect();
        let function_capabilities = provider_capabilities(&registration.function_providers);
        let method_capabilities = provider_capabilities(&registration.method_providers);
        let function_assertion_capabilities = provider_capabilities(&registration.function_assertion_providers);
        let method_assertion_capabilities = provider_capabilities(&registration.method_assertion_providers);

        Self {
            transport,
            registration,
            provider_response_cache: Mutex::new(ProviderResponseCache::default()),
            function_capabilities,
            method_capabilities,
            function_assertion_capabilities,
            method_assertion_capabilities,
            function_exact,
            function_wildcard,
            function_signature_exact,
            function_signature_wildcard,
            function_assertion_exact,
            function_assertion_wildcard,
            method_exact,
            method_wildcard,
            method_signature_exact,
            method_signature_wildcard,
            method_assertion_exact,
            method_assertion_wildcard,
            property_exact,
            property_wildcard,
            property_initialization_exact,
            property_initialization_wildcard,
            class_initializer_exact,
            class_initializer_wildcard,
            issue_filter_indices,
            issue_filter_codes,
        }
    }

    fn matching_function_providers(&self, function: &[u8], declared: bool) -> (Option<ProviderIndices>, usize) {
        let (indices, candidates) =
            matching_function_provider_indices(&self.function_exact, &self.function_wildcard, function);
        let indices = filter_declared_provider_indices(
            indices,
            &self.function_capabilities,
            declared,
            PROVIDER_UNDECLARED_RETURN_TYPE_ONLY,
            false,
        );
        (indices, candidates)
    }

    fn memoizes_function_providers(&self, indices: &[u16]) -> bool {
        providers_have_capability(&self.function_capabilities, indices, PROVIDER_MEMOIZED)
    }

    fn memoizes_method_providers(&self, indices: &[u16]) -> bool {
        providers_have_capability(&self.method_capabilities, indices, PROVIDER_MEMOIZED)
    }

    fn matching_method_providers(
        &self,
        codebase: &CodebaseMetadata,
        class: &[u8],
        method: &[u8],
        declared: bool,
    ) -> (Option<ProviderIndices>, usize) {
        let (indices, candidates) =
            matching_method_provider_indices(&self.method_exact, &self.method_wildcard, codebase, class, method);
        let indices = filter_declared_provider_indices(
            indices,
            &self.method_capabilities,
            declared,
            PROVIDER_UNDECLARED_RETURN_TYPE_ONLY,
            false,
        );
        (indices, candidates)
    }

    fn matching_function_signature_providers(
        &self,
        function: &[u8],
        declared: bool,
    ) -> (Option<ProviderIndices>, usize) {
        let (indices, candidates) = matching_function_provider_indices(
            &self.function_signature_exact,
            &self.function_signature_wildcard,
            function,
        );
        let indices = filter_declared_provider_indices(
            indices,
            &self.function_capabilities,
            declared,
            PROVIDER_OVERRIDES_DECLARED_SIGNATURE,
            true,
        );
        (indices, candidates)
    }

    fn matching_method_signature_providers(
        &self,
        codebase: &CodebaseMetadata,
        class: &[u8],
        method: &[u8],
        declared: bool,
    ) -> (Option<ProviderIndices>, usize) {
        let (indices, candidates) = matching_method_provider_indices(
            &self.method_signature_exact,
            &self.method_signature_wildcard,
            codebase,
            class,
            method,
        );
        let indices = filter_declared_provider_indices(
            indices,
            &self.method_capabilities,
            declared,
            PROVIDER_OVERRIDES_DECLARED_SIGNATURE,
            true,
        );
        (indices, candidates)
    }

    fn matching_function_assertion_providers(&self, function: &[u8]) -> (Option<ProviderIndices>, usize) {
        matching_function_provider_indices(&self.function_assertion_exact, &self.function_assertion_wildcard, function)
    }

    fn matching_method_assertion_providers(
        &self,
        codebase: &CodebaseMetadata,
        class: &[u8],
        method: &[u8],
    ) -> (Option<ProviderIndices>, usize) {
        matching_method_provider_indices(
            &self.method_assertion_exact,
            &self.method_assertion_wildcard,
            codebase,
            class,
            method,
        )
    }

    fn memoizes_function_assertion_providers(&self, indices: &[u16]) -> bool {
        providers_have_capability(&self.function_assertion_capabilities, indices, PROVIDER_MEMOIZED)
    }

    fn memoizes_method_assertion_providers(&self, indices: &[u16]) -> bool {
        providers_have_capability(&self.method_assertion_capabilities, indices, PROVIDER_MEMOIZED)
    }

    fn matching_property_providers(
        &self,
        codebase: &CodebaseMetadata,
        class: &[u8],
        property: &[u8],
    ) -> (Option<ProviderIndices>, usize) {
        matching_property_provider_indices(&self.property_exact, &self.property_wildcard, codebase, class, property)
    }

    fn matching_property_initialization_providers(
        &self,
        codebase: &CodebaseMetadata,
        class: &[u8],
        property: &[u8],
    ) -> (Option<ProviderIndices>, usize) {
        matching_property_provider_indices(
            &self.property_initialization_exact,
            &self.property_initialization_wildcard,
            codebase,
            class,
            property,
        )
    }

    fn matching_class_initializer_providers(
        &self,
        codebase: &CodebaseMetadata,
        class: &[u8],
    ) -> (Option<ProviderIndices>, usize) {
        let (exact, exact_candidates) = matching_exact_class_providers(&self.class_initializer_exact, codebase, class);
        let candidates = exact_candidates + self.class_initializer_wildcard.len();
        let wildcards = self
            .class_initializer_wildcard
            .iter()
            .filter(|(_, targets)| targets.iter().any(|target| class_pattern_matches(codebase, target, class)))
            .map(|(index, _)| *index);

        (ProviderIndices::add_wildcards(exact, wildcards), candidates)
    }

    fn contribute_entry_point_references(
        &self,
        codebase: &CodebaseMetadata,
        references: &mut SymbolReferences,
    ) -> usize {
        if self.registration.entry_points.is_empty() && self.registration.attributed_entry_points.is_empty() {
            return 0;
        }

        let mut matches = 0;
        for class in codebase.class_likes.values() {
            for entry_point in &self.registration.entry_points {
                if !class_pattern_matches(codebase, &entry_point.target.class, class.name.as_bytes()) {
                    continue;
                }

                let mut matched_class = false;
                for (method, declaring_method) in &class.declaring_method_ids {
                    if !pattern_matches(&entry_point.target.method, method.as_bytes()) {
                        continue;
                    }

                    references.add_symbol_reference_to_class_member(
                        entry_point.source,
                        (declaring_method.get_class_name(), declaring_method.get_method_name()),
                        false,
                    );
                    matched_class = true;
                    matches += 1;
                }
                if matched_class {
                    references.add_symbol_reference_to_symbol(entry_point.source, class.name, false);
                }
            }

            for entry_point in &self.registration.attributed_entry_points {
                if !class_pattern_matches(codebase, &entry_point.class, class.name.as_bytes()) {
                    continue;
                }

                let mut matched_class = false;
                for declaring_method in class.declaring_method_ids.values() {
                    let Some(method) = codebase.get_method_by_id(declaring_method) else {
                        continue;
                    };
                    if !method
                        .attributes
                        .iter()
                        .any(|attribute| attribute.name.as_bytes().eq_ignore_ascii_case(&entry_point.attribute))
                    {
                        continue;
                    }

                    references.add_symbol_reference_to_class_member(
                        entry_point.source,
                        (declaring_method.get_class_name(), declaring_method.get_method_name()),
                        false,
                    );
                    matched_class = true;
                    matches += 1;
                }
                if matched_class {
                    references.add_symbol_reference_to_symbol(entry_point.source, class.name, false);
                }
            }
        }

        matches
    }
}

fn index_class_providers(
    providers: &[ClassInitializerProvider],
) -> (ProviderExactIndex, ProviderWildcardIndex<Vec<u8>>) {
    let mut exact = WordMap::default();
    let mut wildcard = Vec::new();
    for provider in providers {
        let mut wildcard_targets = Vec::new();
        for target in &provider.targets {
            if target.contains(&b'*') {
                wildcard_targets.push(target.clone());
            } else {
                let indices = exact.entry(ascii_lowercase_word(target)).or_insert_with(Vec::new);
                if indices.last() != Some(&provider.index) {
                    indices.push(provider.index);
                }
            }
        }

        if !wildcard_targets.is_empty() {
            wildcard.push((provider.index, wildcard_targets));
        }
    }

    (exact, wildcard)
}

fn index_function_providers<'provider>(
    providers: impl IntoIterator<Item = &'provider ProviderRegistration<FunctionTarget>>,
) -> (ProviderExactIndex, ProviderWildcardIndex<FunctionTarget>) {
    let mut exact = WordMap::default();
    let mut wildcard = Vec::new();
    for provider in providers {
        let mut wildcard_targets = Vec::new();
        for target in &provider.targets {
            match target {
                FunctionTarget::Exact(name) => push_provider_index(
                    exact.entry(ascii_lowercase_word(name)).or_insert_with(Vec::new),
                    provider.index,
                ),
                FunctionTarget::Prefix(_) => wildcard_targets.push(target.clone()),
            }
        }
        if !wildcard_targets.is_empty() {
            wildcard.push((provider.index, wildcard_targets));
        }
    }

    (exact, wildcard)
}

fn index_method_providers<'provider>(
    providers: impl IntoIterator<Item = &'provider ProviderRegistration<MethodTarget>>,
) -> (ProviderExactIndex, ProviderWildcardIndex<MethodTarget>) {
    let mut exact = WordMap::default();
    let mut wildcard = Vec::new();
    for provider in providers {
        let mut wildcard_targets = Vec::new();
        for target in &provider.targets {
            if target.class.contains(&b'*') || target.method.contains(&b'*') {
                wildcard_targets.push(target.clone());
            } else {
                let class = ascii_lowercase_word(&target.class);
                let method = ascii_lowercase_word(&target.method);
                push_provider_index(
                    exact.entry(concat_word!(class, b"::", method)).or_insert_with(Vec::new),
                    provider.index,
                );
            }
        }
        if !wildcard_targets.is_empty() {
            wildcard.push((provider.index, wildcard_targets));
        }
    }

    (exact, wildcard)
}

fn push_provider_index(indices: &mut Vec<u16>, index: u16) {
    if indices.last() != Some(&index) {
        indices.push(index);
    }
}

fn matching_function_provider_indices(
    exact_index: &ProviderExactIndex,
    wildcard_index: &ProviderWildcardIndex<FunctionTarget>,
    function: &[u8],
) -> (Option<ProviderIndices>, usize) {
    let function = ascii_lowercase_word(function);
    let exact = exact_index.get(&function).map_or(&[][..], Vec::as_slice);
    let candidates = exact.len() + wildcard_index.len();
    let wildcards = wildcard_index
        .iter()
        .filter(|(_, targets)| targets.iter().any(|target| target.matches(function.as_bytes())))
        .map(|(index, _)| *index);

    (ProviderIndices::from_exact_and_wildcards(exact, wildcards), candidates)
}

fn matching_method_provider_indices(
    exact_index: &ProviderExactIndex,
    wildcard_index: &ProviderWildcardIndex<MethodTarget>,
    codebase: &CodebaseMetadata,
    class: &[u8],
    method: &[u8],
) -> (Option<ProviderIndices>, usize) {
    let (exact, exact_candidates) =
        matching_exact_member_providers(exact_index, codebase, class, ascii_lowercase_word(method).as_bytes());
    let candidates = exact_candidates + wildcard_index.len();
    let wildcards = wildcard_index
        .iter()
        .filter(|(_, targets)| targets.iter().any(|target| target.matches(codebase, class, method)))
        .map(|(index, _)| *index);

    (ProviderIndices::add_wildcards(exact, wildcards), candidates)
}

fn filter_provider_indices(
    indices: Option<ProviderIndices>,
    predicate: impl Fn(u16) -> bool,
) -> Option<ProviderIndices> {
    indices.and_then(|indices| {
        ProviderIndices::from_iter(indices.as_slice().iter().copied().filter(|&index| predicate(index)))
    })
}

fn filter_declared_provider_indices(
    indices: Option<ProviderIndices>,
    capabilities: &[u8],
    declared: bool,
    capability: u8,
    required: bool,
) -> Option<ProviderIndices> {
    if !declared {
        return indices;
    }

    filter_provider_indices(indices, |index| {
        capabilities.get(usize::from(index)).is_some_and(|flags| (flags & capability != 0) == required)
    })
}

fn providers_have_capability(capabilities: &[u8], indices: &[u16], capability: u8) -> bool {
    indices.iter().all(|index| capabilities.get(usize::from(*index)).is_some_and(|flags| flags & capability != 0))
}

fn matching_exact_class_providers(
    index: &ProviderExactIndex,
    codebase: &CodebaseMetadata,
    class: &[u8],
) -> (Option<ProviderIndices>, usize) {
    let mut providers: Option<ProviderIndices> = None;
    let mut candidates = 0;
    for candidate in class_hierarchy(codebase, class) {
        let Some(indices) = index.get(&candidate) else {
            continue;
        };
        candidates += indices.len();
        for provider in indices {
            match &mut providers {
                Some(providers) => providers.insert_sorted(*provider),
                None => providers = Some(ProviderIndices::One(*provider)),
            }
        }
    }

    (providers, candidates)
}

fn index_property_providers(
    providers: &[PropertyProvider],
) -> (ProviderExactIndex, ProviderWildcardIndex<PropertyTarget>) {
    let mut exact = WordMap::default();
    let mut wildcard = Vec::new();
    for provider in providers {
        let mut wildcard_targets = Vec::new();
        for target in &provider.targets {
            if target.class.contains(&b'*') || target.property.contains(&b'*') {
                wildcard_targets.push(target.clone());
            } else {
                let class = ascii_lowercase_word(&target.class);
                let indices =
                    exact.entry(concat_word!(class, b"::", target.property.as_slice())).or_insert_with(Vec::new);
                if indices.last() != Some(&provider.index) {
                    indices.push(provider.index);
                }
            }
        }

        if !wildcard_targets.is_empty() {
            wildcard.push((provider.index, wildcard_targets));
        }
    }

    (exact, wildcard)
}

fn matching_property_provider_indices(
    exact_index: &ProviderExactIndex,
    wildcard_index: &ProviderWildcardIndex<PropertyTarget>,
    codebase: &CodebaseMetadata,
    class: &[u8],
    property: &[u8],
) -> (Option<ProviderIndices>, usize) {
    let (exact, exact_candidates) = matching_exact_member_providers(exact_index, codebase, class, property);
    let candidates = exact_candidates + wildcard_index.len();
    let wildcards = wildcard_index
        .iter()
        .filter(|(_, targets)| targets.iter().any(|target| target.matches(codebase, class, property)))
        .map(|(index, _)| *index);

    (ProviderIndices::add_wildcards(exact, wildcards), candidates)
}

fn matching_exact_member_providers(
    index: &WordMap<Vec<u16>>,
    codebase: &CodebaseMetadata,
    class: &[u8],
    member: &[u8],
) -> (Option<ProviderIndices>, usize) {
    let mut providers: Option<ProviderIndices> = None;
    let mut candidates = 0;
    for candidate in class_hierarchy(codebase, class) {
        let key = concat_word!(candidate, b"::", member);
        let Some(indices) = index.get(&key) else {
            continue;
        };
        candidates += indices.len();
        for provider in indices {
            match &mut providers {
                Some(providers) => providers.insert_sorted(*provider),
                None => providers = Some(ProviderIndices::One(*provider)),
            }
        }
    }

    (providers, candidates)
}

fn class_hierarchy<'codebase>(
    codebase: &'codebase CodebaseMetadata,
    class: &[u8],
) -> impl Iterator<Item = Word> + 'codebase {
    let class = ascii_lowercase_word(class);
    std::iter::once(class).chain(codebase.get_class_like(class.as_bytes()).into_iter().flat_map(|metadata| {
        metadata
            .all_parent_classes
            .iter()
            .chain(&metadata.all_parent_interfaces)
            .chain(&metadata.used_traits)
            .chain(&metadata.require_extends)
            .chain(&metadata.require_implements)
            .copied()
    }))
}

#[derive(Debug)]
pub struct ExternalAnalyzer<T = WorkerPool> {
    backends: Box<[Backend<T>]>,
    extensions: Box<[ExternalExtension]>,
    initialization_stubs: Box<[ExternalStub]>,
    trace_enabled: bool,
    telemetry: ExternalAnalyzerTelemetry,
    started_at: Option<Instant>,
}

#[derive(Debug, Clone, Copy)]
pub(crate) struct ExternalAnalyzerCapabilities {
    pub function_return_types: bool,
    pub method_return_types: bool,
    pub function_signatures: bool,
    pub method_signatures: bool,
    pub function_assertions: bool,
    pub method_assertions: bool,
    pub property_types: bool,
    pub property_initialization: bool,
    pub class_initializers: bool,
    pub issue_filters: bool,
    pub method_call_analysis: bool,
    pub after_file_analysis: bool,
    pub after_analysis: bool,
}

/// An analyzer initialized concurrently with the codebase pipeline.
#[derive(Debug)]
pub struct ExternalAnalyzerHandle {
    analyzer: OnceLock<ExternalAnalyzerResult<ExternalAnalyzer>>,
    initializer: Mutex<Option<JoinHandle<Result<ExternalAnalyzer, ExternalAnalyzerError>>>>,
    trace_enabled: bool,
    started_at: Option<Instant>,
    prepare_calls: AtomicU64,
    initialization_wait_ns: AtomicU64,
}

impl ExternalAnalyzerHandle {
    /// Wraps an analyzer that has already completed initialization.
    #[must_use]
    pub fn ready(analyzer: ExternalAnalyzer) -> Self {
        let trace_enabled = tracing::enabled!(tracing::Level::TRACE);
        let cell = OnceLock::new();
        let _result = cell.set(Ok(analyzer));
        tracing::trace!("Created ready external analyzer handle.");
        Self {
            analyzer: cell,
            initializer: Mutex::new(None),
            trace_enabled,
            started_at: trace_enabled.then(Instant::now),
            prepare_calls: AtomicU64::new(0),
            initialization_wait_ns: AtomicU64::new(0),
        }
    }

    /// Wraps an analyzer initialization thread without waiting for it.
    #[must_use]
    pub fn pending(initializer: JoinHandle<Result<ExternalAnalyzer, ExternalAnalyzerError>>) -> Self {
        let trace_enabled = tracing::enabled!(tracing::Level::TRACE);
        tracing::trace!("Created pending external analyzer handle.");
        Self {
            analyzer: OnceLock::new(),
            initializer: Mutex::new(Some(initializer)),
            trace_enabled,
            started_at: trace_enabled.then(Instant::now),
            prepare_calls: AtomicU64::new(0),
            initialization_wait_ns: AtomicU64::new(0),
        }
    }

    pub(crate) fn prepare(&self) -> ExternalAnalyzerResult<()> {
        if self.trace_enabled {
            self.prepare_calls.fetch_add(1, Ordering::Relaxed);
        }
        self.get().map(|_| ())
    }

    pub(crate) fn initialization_files(&self) -> ExternalAnalyzerResult<Vec<File>> {
        Ok(self.get()?.initialization_stubs.iter().map(ExternalStub::to_file).collect())
    }

    pub(crate) fn with<R>(
        &self,
        operation: impl FnOnce(&ExternalAnalyzer) -> Result<R, ExternalAnalyzerError>,
    ) -> ExternalAnalyzerResult<R> {
        operation(self.get()?).map_err(Arc::new)
    }

    pub(crate) fn read<R>(&self, operation: impl FnOnce(&ExternalAnalyzer) -> R) -> ExternalAnalyzerResult<R> {
        Ok(operation(self.get()?))
    }

    fn get(&self) -> ExternalAnalyzerResult<&ExternalAnalyzer> {
        self.analyzer
            .get_or_init(|| {
                let wait_start = self.trace_enabled.then(Instant::now);
                tracing::trace!("Waiting for external analyzer initialization thread.");
                let initializer = self
                    .initializer
                    .lock()
                    .unwrap_or_else(std::sync::PoisonError::into_inner)
                    .take()
                    .ok_or_else(|| Arc::new(ExternalAnalyzerError::InitializationUnavailable))?;
                let result = initializer
                    .join()
                    .map_err(|_| Arc::new(ExternalAnalyzerError::InitializationPanicked))?
                    .map_err(Arc::new);

                if let Some(start) = wait_start {
                    self.initialization_wait_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
                    tracing::trace!(
                        elapsed = ?start.elapsed(),
                        success = result.is_ok(),
                        "External analyzer initialization thread joined."
                    );
                }

                result
            })
            .as_ref()
            .map_err(Clone::clone)
    }
}

impl Drop for ExternalAnalyzerHandle {
    fn drop(&mut self) {
        if self.analyzer.get().is_none() {
            let initializer = self.initializer.get_mut().unwrap_or_else(std::sync::PoisonError::into_inner).take();
            if let Some(initializer) = initializer {
                tracing::trace!("Joining unused external analyzer initialization thread during shutdown.");
                let _result = initializer.join();
            }
        }

        if self.trace_enabled {
            tracing::trace!(
                initialized = self.analyzer.get().is_some(),
                prepare_calls = self.prepare_calls.load(Ordering::Relaxed),
                initialization_wait = ?Duration::from_nanos(self.initialization_wait_ns.load(Ordering::Relaxed)),
                lifetime = ?self.started_at.map(|start| start.elapsed()).unwrap_or_default(),
                "External analyzer handle dropped."
            );
        }
    }
}

impl ExternalAnalyzer<WorkerPool> {
    /// Discovers and validates the analyzer plugins exposed by worker pools.
    ///
    /// # Errors
    ///
    /// Returns an error when a worker fails, sends malformed metadata, disagrees
    /// with another process in its pool, or advertises duplicate identifiers.
    pub fn initialize(
        pools: impl IntoIterator<Item = Arc<WorkerPool>>,
        php_version: PHPVersion,
        enabled_plugins: &[String],
        disable_defaults: bool,
    ) -> Result<Self, ExternalAnalyzerError> {
        let analyzer = Self::initialize_transports(pools, php_version, enabled_plugins, disable_defaults)?;
        for backend in &analyzer.backends {
            if backend.registration.has_worker_reducer {
                backend.transport.enable_worker_reduction();
            }
        }

        Ok(analyzer)
    }
}

impl<T> ExternalAnalyzer<T> {
    fn record_error(&self) {
        if self.trace_enabled {
            self.telemetry.errors.fetch_add(1, Ordering::Relaxed);
        }
    }

    fn record_lifecycle_error(&self) {
        if self.trace_enabled {
            self.telemetry.lifecycle_errors.fetch_add(1, Ordering::Relaxed);
            self.telemetry.errors.fetch_add(1, Ordering::Relaxed);
        }
    }

    fn record_issue_filter_error(&self) {
        if self.trace_enabled {
            self.telemetry.issue_filter_errors.fetch_add(1, Ordering::Relaxed);
            self.telemetry.errors.fetch_add(1, Ordering::Relaxed);
        }
    }

    #[must_use]
    pub fn extensions(&self) -> &[ExternalExtension] {
        &self.extensions
    }

    #[must_use]
    pub fn initialization_files(&self) -> Vec<File> {
        self.initialization_stubs.iter().map(ExternalStub::to_file).collect()
    }

    pub(crate) fn capabilities(&self) -> ExternalAnalyzerCapabilities {
        let any = |predicate: fn(&Backend<T>) -> bool| self.backends.iter().any(predicate);
        ExternalAnalyzerCapabilities {
            function_return_types: any(|backend| !backend.registration.function_providers.is_empty()),
            method_return_types: any(|backend| !backend.registration.method_providers.is_empty()),
            function_signatures: any(|backend| {
                backend
                    .registration
                    .function_providers
                    .iter()
                    .any(|provider| provider.capabilities & PROVIDER_CALLABLE_SIGNATURE != 0)
            }),
            method_signatures: any(|backend| {
                backend
                    .registration
                    .method_providers
                    .iter()
                    .any(|provider| provider.capabilities & PROVIDER_CALLABLE_SIGNATURE != 0)
            }),
            function_assertions: any(|backend| !backend.registration.function_assertion_providers.is_empty()),
            method_assertions: any(|backend| !backend.registration.method_assertion_providers.is_empty()),
            property_types: any(|backend| !backend.registration.property_providers.is_empty()),
            property_initialization: any(|backend| !backend.registration.property_initialization_providers.is_empty()),
            class_initializers: any(|backend| !backend.registration.class_initializer_providers.is_empty()),
            issue_filters: any(|backend| !backend.issue_filter_indices.is_empty()),
            method_call_analysis: any(|backend| !backend.registration.method_call_analysis_hooks.is_empty()),
            after_file_analysis: any(|backend| {
                !backend.registration.after_file_analysis_plugins.is_empty()
                    || !backend.registration.node_analysis_plugins.is_empty()
            }),
            after_analysis: any(|backend| !backend.registration.after_analysis_plugins.is_empty()),
        }
    }

    pub(crate) fn node_analysis_requirements(&self) -> Option<NodeAnalysisRequirements> {
        let mut targets = [false; u8::MAX as usize + 1];
        let mut requirements = [0; u8::MAX as usize + 1];
        let mut any = false;
        for backend in &self.backends {
            for hook in &backend.registration.node_analysis_hooks {
                for target in &hook.targets {
                    targets[*target as usize] = true;
                    requirements[*target as usize] |= hook.requirements;
                    any = true;
                }
            }
        }

        let method_call_hooks: Arc<[MethodCallAnalysisHookRegistration]> = self
            .backends
            .iter()
            .flat_map(|backend| backend.registration.method_call_analysis_hooks.iter().cloned())
            .collect::<Vec<_>>()
            .into();
        any |= !method_call_hooks.is_empty();

        let class_like_hooks: Arc<[ClassLikeAnalysisHookRegistration]> = self
            .backends
            .iter()
            .flat_map(|backend| backend.registration.class_like_analysis_hooks.iter().cloned())
            .collect::<Vec<_>>()
            .into();
        any |= !class_like_hooks.is_empty();

        any.then_some(NodeAnalysisRequirements { targets, requirements, method_call_hooks, class_like_hooks })
    }
}

impl<T> ExternalAnalyzer<T>
where
    T: AnalyzerTransport,
{
    pub(crate) fn codebase_scan_plan(&self) -> Result<Option<CodebaseScanPlan>, ExternalAnalyzerError> {
        CodebaseScanPlan::compile(&self.backends)
    }

    pub(crate) fn run_codebase_scan(&self, files: Vec<CodebaseScanFile>) -> Result<(), ExternalAnalyzerError> {
        scan::dispatch(&self.backends, files)
    }

    pub(crate) fn filter_issues(
        &self,
        file: &File,
        mut issues: IssueCollection,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<IssueCollection, ExternalAnalyzerError> {
        for backend in &self.backends {
            let hooks = &backend.issue_filter_indices;
            if hooks.is_empty() || issues.is_empty() {
                continue;
            }

            let mut candidate_indices = Vec::new();
            let mut candidates = Vec::new();
            for (index, issue) in issues.iter().enumerate() {
                if issue.code.as_ref().is_some_and(|code| backend.issue_filter_codes.contains(code)) {
                    candidate_indices.push(index);
                    candidates.push(issue);
                }
            }
            if candidates.is_empty() {
                continue;
            }

            let started_at = self.trace_enabled.then(Instant::now);
            let encode_start = self.trace_enabled.then(Instant::now);
            let issue_count = candidates.len();
            let request =
                protocol::encode_issue_filter_request(hooks, file, &candidates, session.generation(), session)
                    .inspect_err(|_| self.record_issue_filter_error())?;
            if let Some(start) = encode_start {
                self.telemetry.issue_filter_encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
                self.telemetry.issue_filter_batches.fetch_add(1, Ordering::Relaxed);
                self.telemetry.issue_filter_candidates.fetch_add(issue_count as u64, Ordering::Relaxed);
                self.telemetry.issue_filter_request_bytes.fetch_add(request.len() as u64, Ordering::Relaxed);
            }

            let nested_telemetry = &self.telemetry;
            let trace_enabled = self.trace_enabled;
            let mut handler = |frame: &Frame| {
                let nested_start = trace_enabled.then(Instant::now);
                let result = protocol::handle_nested_request(&frame.payload, codebase, session, |_| None);
                if let Some(start) = nested_start {
                    nested_telemetry.record_nested_request(frame.payload.len(), start.elapsed(), &result);
                }

                result.map(|(_, response)| response).map_err(|error| error.to_string().into_bytes())
            };

            let ipc_start = self.trace_enabled.then(Instant::now);
            let response = backend
                .transport
                .request_with_handler(request, &mut handler)
                .inspect_err(|_| self.record_issue_filter_error())?;

            if let Some(start) = ipc_start {
                self.telemetry.issue_filter_ipc_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
                self.telemetry.issue_filter_response_bytes.fetch_add(response.len() as u64, Ordering::Relaxed);
            }

            let decode_start = self.trace_enabled.then(Instant::now);
            let removed = protocol::decode_issue_filter_response(&response, issue_count)
                .inspect_err(|_| self.record_issue_filter_error())?;
            let removed = removed.into_iter().map(|index| candidate_indices[index]).collect::<Vec<_>>();

            if let Some(start) = decode_start {
                self.telemetry.issue_filter_decode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
                self.telemetry.issue_filter_removed.fetch_add(removed.len() as u64, Ordering::Relaxed);
            }

            let removed_count = removed.len();
            if removed_count != 0 {
                let mut removed = removed.into_iter();
                let mut next_removed = removed.next();
                issues = IssueCollection::from(issues.into_iter().enumerate().filter_map(|(index, issue)| {
                    if next_removed == Some(index) {
                        next_removed = removed.next();
                        None
                    } else {
                        Some(issue)
                    }
                }));
            }

            if let Some(start) = started_at {
                let elapsed = start.elapsed();
                self.telemetry.issue_filter_ns.fetch_add(duration_nanos(elapsed), Ordering::Relaxed);
                if elapsed >= SLOW_LIFECYCLE_THRESHOLD {
                    tracing::trace!(
                        file = %String::from_utf8_lossy(&file.name),
                        hooks = hooks.len(),
                        candidates = issue_count,
                        removed = removed_count,
                        retained = issues.len(),
                        response_bytes = response.len(),
                        elapsed = ?elapsed,
                        "Slow external analyzer issue-filter batch completed."
                    );
                }
            }
        }

        Ok(issues)
    }

    fn dispatch_lifecycle_request<H>(
        &self,
        backend: &Backend<T>,
        phase: LifecyclePhase,
        plugins: &[u16],
        logical_callbacks: usize,
        request: Vec<u8>,
        handler: &mut H,
        session: &ExternalAnalysisSession,
        default_file: Option<&File>,
        codebase: &CodebaseMetadata,
        started_at: Option<Instant>,
    ) -> Result<lifecycle::LifecycleEffects, ExternalAnalyzerError>
    where
        H: WorkerRequestHandler,
    {
        if self.trace_enabled {
            match phase {
                LifecyclePhase::Before => {
                    self.telemetry.before_analysis_requests.fetch_add(1, Ordering::Relaxed);
                }
                LifecyclePhase::AfterFile | LifecyclePhase::AfterFileBatch => {
                    self.telemetry.after_file_analysis_requests.fetch_add(1, Ordering::Relaxed);
                }
                LifecyclePhase::After => {
                    self.telemetry.after_analysis_requests.fetch_add(1, Ordering::Relaxed);
                }
            }

            self.telemetry.lifecycle_plugins.fetch_add(logical_callbacks as u64, Ordering::Relaxed);
            self.telemetry.lifecycle_request_bytes.fetch_add(request.len() as u64, Ordering::Relaxed);
        }

        let ipc_start = self.trace_enabled.then(Instant::now);
        let response =
            backend.transport.request_with_handler(request, handler).inspect_err(|_| self.record_lifecycle_error())?;

        if let Some(start) = ipc_start {
            self.telemetry.lifecycle_ipc_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            self.telemetry.lifecycle_response_bytes.fetch_add(response.len() as u64, Ordering::Relaxed);
        }

        let decode_start = self.trace_enabled.then(Instant::now);
        let issues = lifecycle::decode_lifecycle_response(
            &response,
            phase.request_kind(),
            plugins,
            &backend.registration.plugins,
            session,
            default_file,
            codebase,
        )
        .inspect_err(|_| self.record_lifecycle_error())?;

        if let Some(start) = decode_start {
            self.telemetry.lifecycle_decode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            self.telemetry.lifecycle_issues.fetch_add(issues.issues.len() as u64, Ordering::Relaxed);
        }

        if let Some(start) = started_at {
            let elapsed = start.elapsed();
            self.telemetry.lifecycle_ns.fetch_add(duration_nanos(elapsed), Ordering::Relaxed);
            if elapsed >= SLOW_LIFECYCLE_THRESHOLD {
                let file = default_file
                    .map_or_else(|| "<project>".into(), |file| String::from_utf8_lossy(&file.name).into_owned());
                tracing::trace!(
                    phase = phase.name(),
                    plugins = plugins.len(),
                    file,
                    response_bytes = response.len(),
                    issues = issues.issues.len(),
                    elapsed = ?elapsed,
                    "Slow external analyzer lifecycle request completed."
                );
            }
        }

        Ok(issues)
    }

    pub(crate) fn run_before_analysis_hooks(
        &self,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<BeforeAnalysisResult, ExternalAnalyzerError> {
        let mut result = BeforeAnalysisResult::default();
        for backend in &self.backends {
            let entry_point_start = self.trace_enabled.then(Instant::now);
            let entry_point_matches = backend.contribute_entry_point_references(codebase, &mut result.references);
            if let Some(start) = entry_point_start
                && (!backend.registration.entry_points.is_empty()
                    || !backend.registration.attributed_entry_points.is_empty())
            {
                tracing::trace!(
                    entry_points = backend.registration.entry_points.len(),
                    attributed_entry_points = backend.registration.attributed_entry_points.len(),
                    matches = entry_point_matches,
                    elapsed = ?start.elapsed(),
                    "Declarative external entry points resolved."
                );
            }

            let plugins = &backend.registration.before_analysis_plugins;
            if plugins.is_empty() {
                continue;
            }
            let lifecycle_start = self.trace_enabled.then(Instant::now);
            let encode_start = self.trace_enabled.then(Instant::now);
            let request = lifecycle::encode_before_analysis_request(session.generation(), plugins)
                .inspect_err(|_| self.record_lifecycle_error())?;

            if let Some(start) = encode_start {
                self.telemetry.lifecycle_encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let nested_telemetry = &self.telemetry;
            let trace_enabled = self.trace_enabled;
            let mut handler = |frame: &Frame| {
                let nested_start = trace_enabled.then(Instant::now);
                let result = protocol::handle_nested_request(&frame.payload, codebase, session, |_| None);
                if let Some(start) = nested_start {
                    nested_telemetry.record_nested_request(frame.payload.len(), start.elapsed(), &result);
                }

                result.map(|(_, response)| response).map_err(|error| error.to_string().into_bytes())
            };

            let effects = self.dispatch_lifecycle_request(
                backend,
                LifecyclePhase::Before,
                plugins,
                plugins.len(),
                request,
                &mut handler,
                session,
                None,
                codebase,
                lifecycle_start,
            )?;
            result.issues.extend(effects.issues);
            result.references.extend(effects.references);
        }

        Ok(result)
    }

    pub(crate) fn run_after_file_analysis_hooks(
        &self,
        file: &File,
        program: &Program<'_>,
        resolved_names: &ResolvedNames<'_>,
        artifacts: &AnalysisArtifacts,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<AfterFileAnalysisResult, ExternalAnalyzerError> {
        let mut result = AfterFileAnalysisResult::default();
        let node_analysis_requirements = self.node_analysis_requirements();
        let store = lifecycle::AnalysisStore::File {
            file,
            program,
            resolved_names,
            artifacts,
            node_analysis_targets: node_analysis_requirements.as_ref().map(NodeAnalysisRequirements::targets),
        };
        for (backend_index, backend) in self.backends.iter().enumerate() {
            let plugins = backend.registration.file_analysis_plugins();
            if plugins.is_empty() {
                continue;
            }
            let include_expression_types = backend.registration.file_analysis_requires_expression_types(&plugins);
            let backend_node_requirements = backend.registration.node_analysis_requirements().filter(|requirements| {
                lifecycle::has_node_analysis_target(program, artifacts, resolved_names, codebase, requirements)
            });

            let lifecycle_start = self.trace_enabled.then(Instant::now);
            let encode_start = self.trace_enabled.then(Instant::now);
            let request = lifecycle::encode_after_file_analysis_request(
                session.generation(),
                &plugins,
                file,
                program,
                resolved_names,
                artifacts,
                codebase,
                include_expression_types,
                backend_node_requirements.as_ref(),
                u16::try_from(backend_index)
                    .map_err(|_| error::protocol("external analyzer backend exceeds u16::MAX"))?,
            )
            .inspect_err(|_| self.record_lifecycle_error())?;

            if let Some(start) = encode_start {
                self.telemetry.lifecycle_encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let nested_telemetry = &self.telemetry;
            let trace_enabled = self.trace_enabled;
            let mut handler = |frame: &Frame| {
                let nested_start = trace_enabled.then(Instant::now);
                let result =
                    if protocol::message_kind(&frame.payload).map_err(|error| error.to_string().into_bytes())? == 8 {
                        lifecycle::handle_analysis_query(&frame.payload, session, &store)
                            .map(|response| (protocol::NestedRequestKind::AnalysisQuery, response))
                    } else {
                        protocol::handle_nested_request(&frame.payload, codebase, session, |_| None)
                    };
                if let Some(start) = nested_start {
                    nested_telemetry.record_nested_request(frame.payload.len(), start.elapsed(), &result);
                }

                result.map(|(_, response)| response).map_err(|error| error.to_string().into_bytes())
            };

            let effects = self.dispatch_lifecycle_request(
                backend,
                LifecyclePhase::AfterFile,
                &plugins,
                plugins.len(),
                request,
                &mut handler,
                session,
                Some(file),
                codebase,
                lifecycle_start,
            )?;
            result.issues.extend(effects.issues);
            extend_references_by_file(&mut result.references_by_file, effects.references_by_file);
        }

        Ok(result)
    }

    pub(crate) fn run_after_file_analysis_batch_hooks(
        &self,
        files: &[Arc<FileAnalysisSnapshot>],
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<AfterFileAnalysisResult, ExternalAnalyzerError> {
        if files.is_empty() {
            return Ok(AfterFileAnalysisResult::default());
        }

        let mut result = AfterFileAnalysisResult::default();
        for (backend_index, backend) in self.backends.iter().enumerate() {
            let plugins = backend.registration.file_analysis_plugins();
            if plugins.is_empty() {
                continue;
            }

            let targeted_files;
            let files = if backend.registration.after_file_analysis_plugins.is_empty() {
                targeted_files =
                    files.iter().filter(|file| file.has_node_analysis_targets()).cloned().collect::<Vec<_>>();
                targeted_files.as_slice()
            } else {
                files
            };
            if files.is_empty() {
                continue;
            }
            let store = lifecycle::AnalysisStore::Project(files);
            let include_expression_types = backend.registration.file_analysis_requires_expression_types(&plugins);
            let backend_node_requirements = backend.registration.node_analysis_requirements();

            let lifecycle_start = self.trace_enabled.then(Instant::now);
            let encode_start = self.trace_enabled.then(Instant::now);
            let request = lifecycle::encode_after_file_analysis_batch_request(
                session.generation(),
                &plugins,
                files,
                include_expression_types,
                backend_node_requirements.as_ref(),
                session,
                u16::try_from(backend_index)
                    .map_err(|_| error::protocol("external analyzer backend exceeds u16::MAX"))?,
            )
            .inspect_err(|_| self.record_lifecycle_error())?;
            if let Some(start) = encode_start {
                self.telemetry.lifecycle_encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
                self.telemetry.after_file_analysis_files.fetch_add(files.len() as u64, Ordering::Relaxed);
            }

            let nested_telemetry = &self.telemetry;
            let trace_enabled = self.trace_enabled;
            let mut handler = |frame: &Frame| {
                let nested_start = trace_enabled.then(Instant::now);
                let result =
                    if protocol::message_kind(&frame.payload).map_err(|error| error.to_string().into_bytes())? == 8 {
                        lifecycle::handle_analysis_query(&frame.payload, session, &store)
                            .map(|response| (protocol::NestedRequestKind::AnalysisQuery, response))
                    } else {
                        protocol::handle_nested_request(&frame.payload, codebase, session, |_| None)
                    };
                if let Some(start) = nested_start {
                    nested_telemetry.record_nested_request(frame.payload.len(), start.elapsed(), &result);
                }

                result.map(|(_, response)| response).map_err(|error| error.to_string().into_bytes())
            };

            let effects = self.dispatch_lifecycle_request(
                backend,
                LifecyclePhase::AfterFileBatch,
                &plugins,
                plugins.len().saturating_mul(files.len()),
                request,
                &mut handler,
                session,
                None,
                codebase,
                lifecycle_start,
            )?;
            result.issues.extend(effects.issues);
            extend_references_by_file(&mut result.references_by_file, effects.references_by_file);
        }

        Ok(result)
    }

    pub(crate) fn run_after_analysis_hooks(
        &self,
        analysis_result: &crate::analysis_result::AnalysisResult,
        files: &[Arc<FileAnalysisSnapshot>],
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<IssueCollection, ExternalAnalyzerError> {
        let mut issues = IssueCollection::new();
        let store = lifecycle::AnalysisStore::Project(files);
        let reference_store = lifecycle::SymbolReferenceStore::new(&analysis_result.symbol_references);
        for backend in &self.backends {
            let plugins = &backend.registration.after_analysis_plugins;
            if plugins.is_empty() {
                continue;
            }

            let lifecycle_start = self.trace_enabled.then(Instant::now);
            let encode_start = self.trace_enabled.then(Instant::now);
            let request =
                lifecycle::encode_after_analysis_request(session.generation(), plugins, analysis_result, files)
                    .inspect_err(|_| self.record_lifecycle_error())?;
            if let Some(start) = encode_start {
                self.telemetry.lifecycle_encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let nested_telemetry = &self.telemetry;
            let trace_enabled = self.trace_enabled;
            let mut handler = |frame: &Frame| {
                let nested_start = trace_enabled.then(Instant::now);
                let kind = protocol::message_kind(&frame.payload).map_err(|error| error.to_string().into_bytes())?;
                let result = if kind == 8 {
                    lifecycle::handle_analysis_query(&frame.payload, session, &store)
                        .map(|response| (protocol::NestedRequestKind::AnalysisQuery, response))
                } else if lifecycle::is_symbol_reference_query(&frame.payload)
                    .map_err(|error| error.to_string().into_bytes())?
                {
                    lifecycle::handle_symbol_reference_query(&frame.payload, session, codebase, &reference_store)
                        .map(|response| (protocol::NestedRequestKind::SymbolReferenceQuery, response))
                } else {
                    protocol::handle_nested_request(&frame.payload, codebase, session, |_| None)
                };
                if let Some(start) = nested_start {
                    nested_telemetry.record_nested_request(frame.payload.len(), start.elapsed(), &result);
                }

                result.map(|(_, response)| response).map_err(|error| error.to_string().into_bytes())
            };

            let effects = self.dispatch_lifecycle_request(
                backend,
                LifecyclePhase::After,
                plugins,
                plugins.len(),
                request,
                &mut handler,
                session,
                None,
                codebase,
                lifecycle_start,
            )?;
            issues.extend(effects.issues);
        }

        Ok(issues)
    }

    fn exchange_provider_request(
        &self,
        backend: &Backend<T>,
        request: &mut protocol::ReturnTypeRequest<'_>,
        affinity: &[u8],
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Vec<u8>, ExternalAnalyzerError> {
        if self.trace_enabled {
            self.telemetry.requests.fetch_add(1, Ordering::Relaxed);
            self.telemetry.snapshotted_types.fetch_add(request.snapshotted_types as u64, Ordering::Relaxed);
            self.telemetry.arguments.fetch_add(request.arguments as u64, Ordering::Relaxed);
            self.telemetry.typed_arguments.fetch_add(request.typed_arguments as u64, Ordering::Relaxed);
            self.telemetry
                .type_snapshot_ns
                .fetch_add(duration_nanos(request.type_snapshot_duration), Ordering::Relaxed);
            self.telemetry.request_bytes.fetch_add(request.payload.len() as u64, Ordering::Relaxed);
        }

        let generation = session.generation();
        let cache_key = request.memoize.then(|| request.payload.clone());
        let cached = cache_key.as_deref().and_then(|cache_key| {
            backend
                .provider_response_cache
                .lock()
                .unwrap_or_else(std::sync::PoisonError::into_inner)
                .get(generation, cache_key)
        });
        let response = if let Some(response) = cached {
            if self.trace_enabled {
                self.telemetry.provider_cache_hits.fetch_add(1, Ordering::Relaxed);
            }
            response
        } else {
            let payload = std::mem::take(&mut request.payload);
            let response = self.exchange_provider_payload(backend, payload, affinity, codebase, session, |handle| {
                protocol::resolve_type_handle(&request.types, handle)
            })?;
            if let Some(cache_key) = cache_key {
                backend.provider_response_cache.lock().unwrap_or_else(std::sync::PoisonError::into_inner).insert(
                    generation,
                    cache_key,
                    response.clone(),
                );
            }
            response
        };

        Ok(response)
    }

    fn decode_provider_response<R>(
        &self,
        decode: impl FnOnce() -> Result<R, ExternalAnalyzerError>,
    ) -> Result<R, ExternalAnalyzerError> {
        let start = self.trace_enabled.then(Instant::now);
        let result = decode().inspect_err(|_| self.record_error());
        if let Some(start) = start {
            self.telemetry.decode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
        }
        result
    }

    fn exchange_provider_payload<'type_info>(
        &self,
        backend: &Backend<T>,
        request: Vec<u8>,
        affinity: &[u8],
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
        resolve_type: impl Fn(usize) -> Option<&'type_info TUnion>,
    ) -> Result<Vec<u8>, ExternalAnalyzerError> {
        let nested_telemetry = &self.telemetry;
        let trace_enabled = self.trace_enabled;
        let mut handler = |frame: &Frame| {
            let nested_start = trace_enabled.then(Instant::now);
            let result = protocol::handle_nested_request(&frame.payload, codebase, session, &resolve_type);
            if let Some(start) = nested_start {
                nested_telemetry.record_nested_request(frame.payload.len(), start.elapsed(), &result);
            }

            result.map(|(_, response)| response).map_err(|error| error.to_string().into_bytes())
        };

        let ipc_start = self.trace_enabled.then(Instant::now);
        if self.trace_enabled {
            self.telemetry.ipc_requests.fetch_add(1, Ordering::Relaxed);
        }
        let response = backend
            .transport
            .request_with_handler_affinity(request, affinity, &mut handler)
            .inspect_err(|_| self.record_error())?;
        if let Some(start) = ipc_start {
            self.telemetry.ipc_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            self.telemetry.response_bytes.fetch_add(response.len() as u64, Ordering::Relaxed);
        }

        Ok(response)
    }

    fn dispatch_assertion_request(
        &self,
        backend: &Backend<T>,
        mut request: protocol::ReturnTypeRequest<'_>,
        affinity: &[u8],
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<InvocationAssertions>, ExternalAnalyzerError> {
        if self.trace_enabled {
            self.telemetry.assertion_requests.fetch_add(1, Ordering::Relaxed);
        }
        let response = self.exchange_provider_request(backend, &mut request, affinity, codebase, session)?;
        let result = self.decode_provider_response(|| {
            protocol::decode_assertion_response(&response, |handle| {
                protocol::resolve_type_handle(&request.types, handle)
            })
        })?;
        if self.trace_enabled {
            if result.is_some() {
                self.telemetry.provided_assertions.fetch_add(1, Ordering::Relaxed);
            } else {
                self.telemetry.declined_requests.fetch_add(1, Ordering::Relaxed);
            }
        }
        Ok(result)
    }

    pub(crate) fn get_function_assertions(
        &self,
        function: &[u8],
        invocation: &Invocation<'_, '_, '_>,
        artifacts: &AnalysisArtifacts,
        source_file: &File,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<InvocationAssertions>, ExternalAnalyzerError> {
        self.get_assertions(CallableTarget::Function(function), invocation, artifacts, source_file, codebase, session)
    }

    pub(crate) fn get_method_assertions(
        &self,
        class: &[u8],
        method: &[u8],
        invocation: &Invocation<'_, '_, '_>,
        artifacts: &AnalysisArtifacts,
        source_file: &File,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<InvocationAssertions>, ExternalAnalyzerError> {
        self.get_assertions(
            CallableTarget::Method { class, method },
            invocation,
            artifacts,
            source_file,
            codebase,
            session,
        )
    }

    fn get_assertions(
        &self,
        target: CallableTarget<'_>,
        invocation: &Invocation<'_, '_, '_>,
        artifacts: &AnalysisArtifacts,
        source_file: &File,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<InvocationAssertions>, ExternalAnalyzerError> {
        let _lookup_trace =
            self.trace_enabled.then(|| LookupTrace { telemetry: &self.telemetry, started_at: Instant::now() });
        if self.trace_enabled {
            self.telemetry.assertion_lookups.fetch_add(1, Ordering::Relaxed);
        }

        for backend in &self.backends {
            let matching_start = self.trace_enabled.then(Instant::now);
            let (indices, candidates) = match target {
                CallableTarget::Function(function) => backend.matching_function_assertion_providers(function),
                CallableTarget::Method { class, method } => {
                    backend.matching_method_assertion_providers(codebase, class, method)
                }
            };
            if self.trace_enabled {
                self.telemetry.backend_checks.fetch_add(1, Ordering::Relaxed);
                self.telemetry.candidate_providers.fetch_add(candidates as u64, Ordering::Relaxed);
            }
            if let Some(start) = matching_start {
                self.telemetry.matching_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let Some(indices) = indices else {
                continue;
            };
            let memoize = match target {
                CallableTarget::Function(_) => backend.memoizes_function_assertion_providers(indices.as_slice()),
                CallableTarget::Method { .. } => backend.memoizes_method_assertion_providers(indices.as_slice()),
            };
            if self.trace_enabled {
                self.telemetry.matched_providers.fetch_add(indices.as_slice().len() as u64, Ordering::Relaxed);
            }

            let encode_start = self.trace_enabled.then(Instant::now);
            let provider_start = self.trace_enabled.then(Instant::now);
            let protocol_target = match target {
                CallableTarget::Function(function) => protocol::ProviderTarget::Function(function),
                CallableTarget::Method { class, method } => protocol::ProviderTarget::Method {
                    class: codebase.get_class_like(class).map_or(class, |metadata| metadata.original_name.as_bytes()),
                    method,
                },
            };
            let request = protocol::encode_provider_request(
                protocol::ProviderRequestKind::Assertion,
                indices.as_slice(),
                protocol_target,
                invocation,
                artifacts,
                source_file,
                session.generation(),
                memoize,
                self.trace_enabled,
            )?;
            if let Some(start) = encode_start {
                self.telemetry.encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let assertions = self.dispatch_assertion_request(backend, request, target.affinity(), codebase, session)?;
            if let Some(start) = provider_start
                && start.elapsed() >= SLOW_PROVIDER_THRESHOLD
            {
                tracing::trace!(
                    target = %target,
                    providers = indices.as_slice().len(),
                    elapsed = ?start.elapsed(),
                    provided = assertions.is_some(),
                    "Slow external assertion provider request completed."
                );
            }
            if assertions.is_some() {
                return Ok(assertions);
            }
        }

        Ok(None)
    }

    fn dispatch_callable_signature_request(
        &self,
        backend: &Backend<T>,
        mut request: protocol::ReturnTypeRequest<'_>,
        affinity: &[u8],
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<EffectiveCallableSignature>, ExternalAnalyzerError> {
        if self.trace_enabled {
            self.telemetry.signature_requests.fetch_add(1, Ordering::Relaxed);
        }
        let response = self.exchange_provider_request(backend, &mut request, affinity, codebase, session)?;
        let result = self.decode_provider_response(|| {
            protocol::decode_callable_signature_response(&response, |handle| {
                protocol::resolve_type_handle(&request.types, handle)
            })
        })?;

        if self.trace_enabled {
            if result.is_some() {
                self.telemetry.provided_signatures.fetch_add(1, Ordering::Relaxed);
            } else {
                self.telemetry.declined_requests.fetch_add(1, Ordering::Relaxed);
            }
        }

        Ok(result)
    }

    pub(crate) fn get_function_callable_signature(
        &self,
        function: &[u8],
        invocation: &Invocation<'_, '_, '_>,
        artifacts: &AnalysisArtifacts,
        source_file: &File,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<EffectiveCallableSignature>, ExternalAnalyzerError> {
        self.get_callable_signature(
            CallableTarget::Function(function),
            invocation,
            artifacts,
            source_file,
            codebase,
            session,
        )
    }

    pub(crate) fn get_method_callable_signature(
        &self,
        class: &[u8],
        method: &[u8],
        invocation: &Invocation<'_, '_, '_>,
        artifacts: &AnalysisArtifacts,
        source_file: &File,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<EffectiveCallableSignature>, ExternalAnalyzerError> {
        self.get_callable_signature(
            CallableTarget::Method { class, method },
            invocation,
            artifacts,
            source_file,
            codebase,
            session,
        )
    }

    fn get_callable_signature(
        &self,
        target: CallableTarget<'_>,
        invocation: &Invocation<'_, '_, '_>,
        artifacts: &AnalysisArtifacts,
        source_file: &File,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<EffectiveCallableSignature>, ExternalAnalyzerError> {
        let _lookup_trace =
            self.trace_enabled.then(|| LookupTrace { telemetry: &self.telemetry, started_at: Instant::now() });
        if self.trace_enabled {
            self.telemetry.signature_lookups.fetch_add(1, Ordering::Relaxed);
        }

        for backend in &self.backends {
            let matching_start = self.trace_enabled.then(Instant::now);
            let (indices, candidates) = match target {
                CallableTarget::Function(function) => {
                    backend.matching_function_signature_providers(function, codebase.get_function(function).is_some())
                }
                CallableTarget::Method { class, method } => backend.matching_method_signature_providers(
                    codebase,
                    class,
                    method,
                    codebase.get_declaring_method(class, method).is_some(),
                ),
            };
            if self.trace_enabled {
                self.telemetry.backend_checks.fetch_add(1, Ordering::Relaxed);
                self.telemetry.candidate_providers.fetch_add(candidates as u64, Ordering::Relaxed);
            }

            if let Some(start) = matching_start {
                self.telemetry.matching_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let Some(indices) = indices else {
                continue;
            };
            let memoize = match target {
                CallableTarget::Function(_) => backend.memoizes_function_providers(indices.as_slice()),
                CallableTarget::Method { .. } => backend.memoizes_method_providers(indices.as_slice()),
            };

            if self.trace_enabled {
                self.telemetry.matched_providers.fetch_add(indices.as_slice().len() as u64, Ordering::Relaxed);
            }

            let encode_start = self.trace_enabled.then(Instant::now);
            let provider_start = self.trace_enabled.then(Instant::now);
            let protocol_target = match target {
                CallableTarget::Function(function) => protocol::ProviderTarget::Function(function),
                CallableTarget::Method { class, method } => protocol::ProviderTarget::Method {
                    class: codebase.get_class_like(class).map_or(class, |metadata| metadata.original_name.as_bytes()),
                    method,
                },
            };
            let request = protocol::encode_provider_request(
                protocol::ProviderRequestKind::CallableSignature,
                indices.as_slice(),
                protocol_target,
                invocation,
                artifacts,
                source_file,
                session.generation(),
                memoize,
                self.trace_enabled,
            )
            .inspect_err(|_| self.record_error())?;

            if let Some(start) = encode_start {
                self.telemetry.encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let signature =
                self.dispatch_callable_signature_request(backend, request, target.affinity(), codebase, session)?;
            if let Some(start) = provider_start
                && start.elapsed() >= SLOW_PROVIDER_THRESHOLD
            {
                tracing::trace!(
                    target = %target,
                    providers = indices.as_slice().len(),
                    elapsed = ?start.elapsed(),
                    provided = signature.is_some(),
                    "Slow external callable-signature provider request completed."
                );
            }

            if let Some(signature) = signature {
                return Ok(Some(signature));
            }
        }

        Ok(None)
    }

    pub(crate) fn get_function_return_type(
        &self,
        function: &[u8],
        invocation: &Invocation<'_, '_, '_>,
        artifacts: &AnalysisArtifacts,
        source_file: &File,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<TUnion>, ExternalAnalyzerError> {
        self.get_return_type(CallableTarget::Function(function), invocation, artifacts, source_file, codebase, session)
    }

    pub(crate) fn get_method_return_type(
        &self,
        class: &[u8],
        method: &[u8],
        invocation: &Invocation<'_, '_, '_>,
        artifacts: &AnalysisArtifacts,
        source_file: &File,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<TUnion>, ExternalAnalyzerError> {
        self.get_return_type(
            CallableTarget::Method { class, method },
            invocation,
            artifacts,
            source_file,
            codebase,
            session,
        )
    }

    fn get_return_type(
        &self,
        target: CallableTarget<'_>,
        invocation: &Invocation<'_, '_, '_>,
        artifacts: &AnalysisArtifacts,
        source_file: &File,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<TUnion>, ExternalAnalyzerError> {
        let _lookup_trace =
            self.trace_enabled.then(|| LookupTrace { telemetry: &self.telemetry, started_at: Instant::now() });
        if self.trace_enabled {
            match target {
                CallableTarget::Function(_) => self.telemetry.function_lookups.fetch_add(1, Ordering::Relaxed),
                CallableTarget::Method { .. } => self.telemetry.method_lookups.fetch_add(1, Ordering::Relaxed),
            };
        }

        let declared = match target {
            CallableTarget::Function(function) => codebase.get_function(function).is_some(),
            CallableTarget::Method { class, method } => codebase.get_declaring_method(class, method).is_some(),
        };
        let mut dispatched = false;
        for backend in &self.backends {
            let matching_start = self.trace_enabled.then(Instant::now);
            let (indices, candidates) = match target {
                CallableTarget::Function(function) => backend.matching_function_providers(function, declared),
                CallableTarget::Method { class, method } => {
                    backend.matching_method_providers(codebase, class, method, declared)
                }
            };
            if self.trace_enabled {
                self.telemetry.backend_checks.fetch_add(1, Ordering::Relaxed);
                self.telemetry.candidate_providers.fetch_add(candidates as u64, Ordering::Relaxed);
            }

            if let Some(start) = matching_start {
                self.telemetry.matching_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let Some(indices) = indices else {
                continue;
            };
            let memoize = match target {
                CallableTarget::Function(_) => backend.memoizes_function_providers(indices.as_slice()),
                CallableTarget::Method { .. } => backend.memoizes_method_providers(indices.as_slice()),
            };
            dispatched = true;
            let provider_start = self.trace_enabled.then(Instant::now);
            if self.trace_enabled {
                self.telemetry.matched_providers.fetch_add(indices.as_slice().len() as u64, Ordering::Relaxed);
            }

            let encode_start = self.trace_enabled.then(Instant::now);
            let protocol_target = match target {
                CallableTarget::Function(function) => protocol::ProviderTarget::Function(function),
                CallableTarget::Method { class, method } => protocol::ProviderTarget::Method {
                    class: codebase.get_class_like(class).map_or(class, |metadata| metadata.original_name.as_bytes()),
                    method,
                },
            };
            let mut request = protocol::encode_provider_request(
                protocol::ProviderRequestKind::ReturnType,
                indices.as_slice(),
                protocol_target,
                invocation,
                artifacts,
                source_file,
                session.generation(),
                memoize,
                self.trace_enabled,
            )
            .inspect_err(|_| self.record_error())?;

            if let Some(start) = encode_start {
                self.telemetry.encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }
            let response =
                self.exchange_provider_request(backend, &mut request, target.affinity(), codebase, session)?;
            let result = self.decode_provider_response(|| {
                protocol::decode_return_type_response(&response, |handle| {
                    protocol::resolve_type_handle(&request.types, handle)
                })
            })?;

            if let Some(start) = provider_start
                && start.elapsed() >= SLOW_PROVIDER_THRESHOLD
            {
                tracing::trace!(
                    target = %target,
                    providers = indices.as_slice().len(),
                    arguments = request.arguments,
                    typed_arguments = request.typed_arguments,
                    argument_types = request.types.len().saturating_sub(request.receiver_type_count),
                    response_bytes = response.len(),
                    elapsed = ?start.elapsed(),
                    provided = result.is_some(),
                    "Slow external return-type provider request completed."
                );
            }

            if let Some(result) = result {
                if self.trace_enabled {
                    self.telemetry.provided_types.fetch_add(1, Ordering::Relaxed);
                }
                return Ok(Some(result));
            }

            if self.trace_enabled {
                self.telemetry.declined_requests.fetch_add(1, Ordering::Relaxed);
            }
        }

        if self.trace_enabled && !dispatched {
            self.telemetry.unmatched_lookups.fetch_add(1, Ordering::Relaxed);
        }

        Ok(None)
    }

    pub(crate) fn get_property_type(
        &self,
        class: &[u8],
        property: &[u8],
        access: PropertyAccessKind,
        receiver_type: &TUnion,
        span: Span,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<Option<EffectivePropertyType>, ExternalAnalyzerError> {
        let _lookup_trace =
            self.trace_enabled.then(|| LookupTrace { telemetry: &self.telemetry, started_at: Instant::now() });
        if self.trace_enabled {
            self.telemetry.property_lookups.fetch_add(1, Ordering::Relaxed);
        }

        let mut dispatched = false;
        for backend in &self.backends {
            let matching_start = self.trace_enabled.then(Instant::now);
            let (indices, candidates) = backend.matching_property_providers(codebase, class, property);
            if self.trace_enabled {
                self.telemetry.backend_checks.fetch_add(1, Ordering::Relaxed);
                self.telemetry.candidate_providers.fetch_add(candidates as u64, Ordering::Relaxed);
            }
            if let Some(start) = matching_start {
                self.telemetry.matching_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let Some(indices) = indices else {
                continue;
            };
            dispatched = true;
            let provider_start = self.trace_enabled.then(Instant::now);
            if self.trace_enabled {
                self.telemetry.requests.fetch_add(1, Ordering::Relaxed);
                self.telemetry.matched_providers.fetch_add(indices.as_slice().len() as u64, Ordering::Relaxed);
            }

            let original_class =
                codebase.get_class_like(class).map_or(class, |metadata| metadata.original_name.as_bytes());
            let encode_start = self.trace_enabled.then(Instant::now);
            let request = protocol::encode_property_type_request(
                indices.as_slice(),
                original_class,
                property,
                access,
                receiver_type,
                span,
                session.generation(),
                self.trace_enabled,
            )
            .inspect_err(|_| self.record_error())?;
            if let Some(start) = encode_start {
                self.telemetry.encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
                self.telemetry.snapshotted_types.fetch_add(request.snapshotted_types as u64, Ordering::Relaxed);
                self.telemetry
                    .type_snapshot_ns
                    .fetch_add(duration_nanos(request.type_snapshot_duration), Ordering::Relaxed);
                self.telemetry.request_bytes.fetch_add(request.payload.len() as u64, Ordering::Relaxed);
            }

            let response =
                self.exchange_provider_payload(backend, request.payload, class, codebase, session, |handle| {
                    protocol::resolve_type_handle(&request.types, handle)
                })?;

            let decode_start = self.trace_enabled.then(Instant::now);
            let result = protocol::decode_property_type_response(&response, |handle| {
                protocol::resolve_type_handle(&request.types, handle)
            })
            .inspect_err(|_| self.record_error())?;
            if let Some(start) = decode_start {
                self.telemetry.decode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            if let Some(start) = provider_start
                && start.elapsed() >= SLOW_PROVIDER_THRESHOLD
            {
                tracing::trace!(
                    class = %mago_bytes::BytesDisplay(class),
                    property = %mago_bytes::BytesDisplay(property),
                    access = ?access,
                    providers = indices.as_slice().len(),
                    receiver_types = request.types.len(),
                    response_bytes = response.len(),
                    elapsed = ?start.elapsed(),
                    provided = result.is_some(),
                    "Slow external property type provider request completed."
                );
            }

            if let Some(result) = result {
                if self.trace_enabled {
                    self.telemetry.provided_types.fetch_add(1, Ordering::Relaxed);
                }
                return Ok(Some(result));
            }
            if self.trace_enabled {
                self.telemetry.declined_requests.fetch_add(1, Ordering::Relaxed);
            }
        }

        if self.trace_enabled && !dispatched {
            self.telemetry.unmatched_lookups.fetch_add(1, Ordering::Relaxed);
        }

        Ok(None)
    }

    pub(crate) fn is_property_initialized(
        &self,
        declaring_class: &[u8],
        property: &mago_codex::metadata::property::PropertyMetadata,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<bool, ExternalAnalyzerError> {
        let property_name = property.name.0.as_bytes().strip_prefix(b"$").unwrap_or(property.name.0.as_bytes());
        let _lookup_trace =
            self.trace_enabled.then(|| LookupTrace { telemetry: &self.telemetry, started_at: Instant::now() });
        if self.trace_enabled {
            self.telemetry.property_initialization_lookups.fetch_add(1, Ordering::Relaxed);
        }

        let mut dispatched = false;
        for backend in &self.backends {
            let matching_start = self.trace_enabled.then(Instant::now);
            let (indices, candidates) =
                backend.matching_property_initialization_providers(codebase, declaring_class, property_name);
            if self.trace_enabled {
                self.telemetry.backend_checks.fetch_add(1, Ordering::Relaxed);
                self.telemetry.candidate_providers.fetch_add(candidates as u64, Ordering::Relaxed);
            }
            if let Some(start) = matching_start {
                self.telemetry.matching_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let Some(indices) = indices else {
                continue;
            };
            dispatched = true;
            let provider_start = self.trace_enabled.then(Instant::now);
            if self.trace_enabled {
                self.telemetry.requests.fetch_add(1, Ordering::Relaxed);
                self.telemetry.matched_providers.fetch_add(indices.as_slice().len() as u64, Ordering::Relaxed);
            }

            let original_class = codebase
                .get_class_like(declaring_class)
                .map_or(declaring_class, |metadata| metadata.original_name.as_bytes());
            let encode_start = self.trace_enabled.then(Instant::now);
            let request = protocol::encode_property_initialization_request(
                indices.as_slice(),
                original_class,
                property,
                session.generation(),
                session,
            )
            .inspect_err(|_| self.record_error())?;

            if let Some(start) = encode_start {
                self.telemetry.encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
                self.telemetry.request_bytes.fetch_add(request.len() as u64, Ordering::Relaxed);
            }

            let response =
                self.exchange_provider_payload(backend, request, declaring_class, codebase, session, |_| None)?;

            let decode_start = self.trace_enabled.then(Instant::now);
            let initialized =
                protocol::decode_property_initialization_response(&response).inspect_err(|_| self.record_error())?;

            if let Some(start) = decode_start {
                self.telemetry.decode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            if let Some(start) = provider_start
                && start.elapsed() >= SLOW_PROVIDER_THRESHOLD
            {
                tracing::trace!(
                    class = %mago_bytes::BytesDisplay(declaring_class),
                    property = %mago_bytes::BytesDisplay(property_name),
                    providers = indices.as_slice().len(),
                    response_bytes = response.len(),
                    elapsed = ?start.elapsed(),
                    initialized,
                    "Slow external property initialization provider request completed."
                );
            }

            if initialized {
                if self.trace_enabled {
                    self.telemetry.initialized_properties.fetch_add(1, Ordering::Relaxed);
                }

                return Ok(true);
            }

            if self.trace_enabled {
                self.telemetry.declined_requests.fetch_add(1, Ordering::Relaxed);
            }
        }

        if self.trace_enabled && !dispatched {
            self.telemetry.unmatched_lookups.fetch_add(1, Ordering::Relaxed);
        }

        Ok(false)
    }

    pub(crate) fn get_class_initializers(
        &self,
        class: &ClassLikeMetadata,
        codebase: &CodebaseMetadata,
        session: &ExternalAnalysisSession,
    ) -> Result<WordSet, ExternalAnalyzerError> {
        let _lookup_trace =
            self.trace_enabled.then(|| LookupTrace { telemetry: &self.telemetry, started_at: Instant::now() });
        if self.trace_enabled {
            self.telemetry.class_initializer_lookups.fetch_add(1, Ordering::Relaxed);
        }

        let mut initializers = WordSet::default();
        let mut dispatched = false;
        for backend in &self.backends {
            let matching_start = self.trace_enabled.then(Instant::now);
            let (indices, candidates) = backend.matching_class_initializer_providers(codebase, class.name.as_bytes());
            if self.trace_enabled {
                self.telemetry.backend_checks.fetch_add(1, Ordering::Relaxed);
                self.telemetry.candidate_providers.fetch_add(candidates as u64, Ordering::Relaxed);
            }
            if let Some(start) = matching_start {
                self.telemetry.matching_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }

            let Some(indices) = indices else {
                continue;
            };
            dispatched = true;
            let provider_start = self.trace_enabled.then(Instant::now);
            if self.trace_enabled {
                self.telemetry.requests.fetch_add(1, Ordering::Relaxed);
                self.telemetry.matched_providers.fetch_add(indices.as_slice().len() as u64, Ordering::Relaxed);
            }

            let encode_start = self.trace_enabled.then(Instant::now);
            let request =
                protocol::encode_class_initializer_request(indices.as_slice(), class, session.generation(), session)
                    .inspect_err(|_| self.record_error())?;
            if let Some(start) = encode_start {
                self.telemetry.encode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
                self.telemetry.request_bytes.fetch_add(request.len() as u64, Ordering::Relaxed);
            }

            let response =
                self.exchange_provider_payload(backend, request, class.name.as_bytes(), codebase, session, |_| None)?;

            let decode_start = self.trace_enabled.then(Instant::now);
            let provided =
                protocol::decode_class_initializer_response(&response).inspect_err(|_| self.record_error())?;
            if let Some(start) = decode_start {
                self.telemetry.decode_ns.fetch_add(duration_nanos(start.elapsed()), Ordering::Relaxed);
            }
            if self.trace_enabled {
                self.telemetry.provided_class_initializers.fetch_add(provided.len() as u64, Ordering::Relaxed);
                if provided.is_empty() {
                    self.telemetry.declined_requests.fetch_add(1, Ordering::Relaxed);
                }
            }

            if let Some(start) = provider_start
                && start.elapsed() >= SLOW_PROVIDER_THRESHOLD
            {
                tracing::trace!(
                    class = %class.original_name,
                    providers = indices.as_slice().len(),
                    initializers = provided.len(),
                    response_bytes = response.len(),
                    elapsed = ?start.elapsed(),
                    "Slow external class initializer provider request completed."
                );
            }

            initializers.extend(provided);
        }

        if self.trace_enabled && !dispatched {
            self.telemetry.unmatched_lookups.fetch_add(1, Ordering::Relaxed);
        }

        Ok(initializers)
    }

    fn initialize_transports(
        transports: impl IntoIterator<Item = Arc<T>>,
        php_version: PHPVersion,
        enabled_plugins: &[String],
        disable_defaults: bool,
    ) -> Result<Self, ExternalAnalyzerError> {
        let trace_enabled = tracing::enabled!(tracing::Level::TRACE);
        let started_at = trace_enabled.then(Instant::now);
        tracing::trace!(
            php_version = %php_version,
            explicitly_enabled_plugins = enabled_plugins.len(),
            disable_defaults,
            "Initializing external analyzer registrations."
        );

        let describe = protocol::encode_describe_request(php_version);
        let mut backends = Vec::new();
        let mut extensions = Vec::new();
        let mut initialization_stubs = Vec::new();
        let mut extension_identifiers = HashSet::new();
        let mut plugin_selectors = HashMap::new();
        for plugin in available_plugins() {
            for selector in std::iter::once(plugin.id).chain(plugin.aliases.iter().copied()) {
                let selector = selector.to_ascii_lowercase();
                if let Some(first) = plugin_selectors.insert(selector.clone(), plugin.id.to_string()) {
                    return Err(ExternalAnalyzerError::DuplicatePluginSelector {
                        selector,
                        first,
                        second: plugin.id.to_string(),
                    });
                }
            }
        }

        for (backend_index, transport) in transports.into_iter().enumerate() {
            let backend_start = trace_enabled.then(Instant::now);
            tracing::trace!(
                backend = backend_index,
                request_bytes = describe.len(),
                "Describing external analyzer backend."
            );

            let responses = transport.broadcast(&describe)?;
            let response_bytes = responses.iter().map(Vec::len).sum::<usize>();
            let mut decoded = responses.iter().map(|response| protocol::decode_registration(response));
            let Some(first) = decoded.next() else {
                return Err(error::protocol("worker pool returned no analyzer registration responses"));
            };

            let mut registration = first?;
            for response in decoded {
                if response? != registration {
                    return Err(ExternalAnalyzerError::InconsistentRegistration);
                }
            }

            for extension in &registration.extensions {
                if !extension_identifiers.insert(extension.identifier.to_ascii_lowercase()) {
                    return Err(ExternalAnalyzerError::DuplicateExtension(extension.identifier.clone()));
                }
            }

            for plugin in &registration.plugins {
                for selector in
                    std::iter::once(plugin.identifier.as_str()).chain(plugin.aliases.iter().map(String::as_str))
                {
                    let selector = selector.to_ascii_lowercase();
                    if let Some(first) = plugin_selectors.insert(selector.clone(), plugin.identifier.clone()) {
                        return Err(ExternalAnalyzerError::DuplicatePluginSelector {
                            selector,
                            first,
                            second: plugin.identifier.clone(),
                        });
                    }
                }
            }

            let enabled = registration
                .plugins
                .iter()
                .filter(|plugin| {
                    enabled_plugins.iter().any(|name| plugin.matches(name))
                        || (!disable_defaults && plugin.default_enabled)
                })
                .map(|plugin| plugin.index)
                .collect::<HashSet<_>>();

            let advertised_function_providers = registration.function_providers.len();
            let advertised_method_providers = registration.method_providers.len();
            let advertised_function_assertion_providers = registration.function_assertion_providers.len();
            let advertised_method_assertion_providers = registration.method_assertion_providers.len();
            let advertised_property_providers = registration.property_providers.len();
            let advertised_property_initialization_providers = registration.property_initialization_providers.len();
            let advertised_class_initializer_providers = registration.class_initializer_providers.len();
            let advertised_entry_points = registration.entry_points.len();
            let advertised_attributed_entry_points = registration.attributed_entry_points.len();
            let advertised_issue_filter_hooks = registration.issue_filter_hooks.len();
            let advertised_node_analysis_hooks = registration.node_analysis_hooks.len();
            let advertised_method_call_analysis_hooks = registration.method_call_analysis_hooks.len();
            let advertised_class_like_analysis_hooks = registration.class_like_analysis_hooks.len();
            let advertised_codebase_scan_hooks = registration.codebase_scan_hooks.len();
            registration.function_providers.retain(|provider| enabled.contains(&provider.plugin));
            registration.method_providers.retain(|provider| enabled.contains(&provider.plugin));
            registration.function_assertion_providers.retain(|provider| enabled.contains(&provider.plugin));
            registration.method_assertion_providers.retain(|provider| enabled.contains(&provider.plugin));
            registration.property_providers.retain(|provider| enabled.contains(&provider.plugin));
            registration.property_initialization_providers.retain(|provider| enabled.contains(&provider.plugin));
            registration.class_initializer_providers.retain(|provider| enabled.contains(&provider.plugin));
            registration.entry_points.retain(|entry_point| enabled.contains(&entry_point.plugin));
            registration.attributed_entry_points.retain(|entry_point| enabled.contains(&entry_point.plugin));
            registration.issue_filter_hooks.retain(|hook| enabled.contains(&hook.plugin));
            registration.node_analysis_hooks.retain(|hook| enabled.contains(&hook.plugin));
            registration.method_call_analysis_hooks.retain(|hook| enabled.contains(&hook.plugin));
            registration.class_like_analysis_hooks.retain(|hook| enabled.contains(&hook.plugin));
            registration.codebase_scan_hooks.retain(|hook| enabled.contains(&hook.plugin));
            let backend_route = u16::try_from(backend_index)
                .map_err(|_| error::protocol("more than 65,536 external analyzer backends were configured"))?;
            for hook in &mut registration.method_call_analysis_hooks {
                hook.route = (u32::from(backend_route) << 16) | u32::from(hook.index);
            }
            for hook in &mut registration.class_like_analysis_hooks {
                hook.route = (u32::from(backend_route) << 16) | u32::from(hook.index);
            }
            registration.initialization_plugins.retain(|index| enabled.contains(index));
            registration.before_analysis_plugins.retain(|index| enabled.contains(index));
            registration.after_file_analysis_plugins.retain(|index| enabled.contains(index));
            registration.node_analysis_plugins.retain(|index| enabled.contains(index));
            registration.after_analysis_plugins.retain(|index| enabled.contains(index));

            if !registration.initialization_plugins.is_empty() {
                let initialize = protocol::encode_initialization_request(&registration.initialization_plugins)?;
                let responses = transport.broadcast(&initialize)?;
                let mut decoded = responses.iter().map(|response| {
                    protocol::decode_initialization_response(response, &registration.initialization_plugins)
                });

                let Some(first) = decoded.next() else {
                    return Err(error::protocol("worker pool returned no analyzer initialization responses"));
                };

                let initialized = first?;
                for response in decoded {
                    if response? != initialized {
                        return Err(ExternalAnalyzerError::InconsistentInitialization);
                    }
                }

                for stub in initialized {
                    let plugin = registration.plugins.get(usize::from(stub.plugin)).ok_or_else(|| {
                        error::protocol(format!("initialization references unknown plugin index {}", stub.plugin))
                    })?;

                    initialization_stubs.push(ExternalStub::new(
                        &plugin.extension,
                        &plugin.identifier,
                        &stub.filename,
                        stub.contents,
                    ));
                }
            }

            extensions.extend(registration.extensions.iter().cloned());
            if let Some(start) = backend_start {
                tracing::trace!(
                    backend = backend_index,
                    workers = responses.len(),
                    response_bytes,
                    extensions = registration.extensions.len(),
                    plugins = registration.plugins.len(),
                    initialization_plugins = registration.initialization_plugins.len(),
                    enabled_plugins = enabled.len(),
                    function_providers = registration.function_providers.len(),
                    disabled_function_providers = advertised_function_providers - registration.function_providers.len(),
                    method_providers = registration.method_providers.len(),
                    disabled_method_providers = advertised_method_providers - registration.method_providers.len(),
                    function_assertion_providers = registration.function_assertion_providers.len(),
                    disabled_function_assertion_providers = advertised_function_assertion_providers
                        - registration.function_assertion_providers.len(),
                    method_assertion_providers = registration.method_assertion_providers.len(),
                    disabled_method_assertion_providers = advertised_method_assertion_providers
                        - registration.method_assertion_providers.len(),
                    property_providers = registration.property_providers.len(),
                    disabled_property_providers = advertised_property_providers - registration.property_providers.len(),
                    property_initialization_providers = registration.property_initialization_providers.len(),
                    disabled_property_initialization_providers = advertised_property_initialization_providers
                        - registration.property_initialization_providers.len(),
                    class_initializer_providers = registration.class_initializer_providers.len(),
                    disabled_class_initializer_providers = advertised_class_initializer_providers
                        - registration.class_initializer_providers.len(),
                    entry_points = registration.entry_points.len(),
                    disabled_entry_points = advertised_entry_points - registration.entry_points.len(),
                    attributed_entry_points = registration.attributed_entry_points.len(),
                    disabled_attributed_entry_points = advertised_attributed_entry_points
                        - registration.attributed_entry_points.len(),
                    issue_filter_hooks = registration.issue_filter_hooks.len(),
                    disabled_issue_filter_hooks = advertised_issue_filter_hooks - registration.issue_filter_hooks.len(),
                    node_analysis_hooks = registration.node_analysis_hooks.len(),
                    disabled_node_analysis_hooks = advertised_node_analysis_hooks - registration.node_analysis_hooks.len(),
                    method_call_analysis_hooks = registration.method_call_analysis_hooks.len(),
                    disabled_method_call_analysis_hooks = advertised_method_call_analysis_hooks
                        - registration.method_call_analysis_hooks.len(),
                    class_like_analysis_hooks = registration.class_like_analysis_hooks.len(),
                    disabled_class_like_analysis_hooks = advertised_class_like_analysis_hooks
                        - registration.class_like_analysis_hooks.len(),
                    codebase_scan_hooks = registration.codebase_scan_hooks.len(),
                    disabled_codebase_scan_hooks = advertised_codebase_scan_hooks
                        - registration.codebase_scan_hooks.len(),
                    before_analysis_plugins = registration.before_analysis_plugins.len(),
                    after_file_analysis_plugins = registration.after_file_analysis_plugins.len(),
                    after_analysis_plugins = registration.after_analysis_plugins.len(),
                    elapsed = ?start.elapsed(),
                    "External analyzer backend registered."
                );
            }

            if !registration.after_file_analysis_plugins.is_empty() || !registration.node_analysis_plugins.is_empty() {
                transport.prepare_capacity();
            }

            backends.push(Backend::new(transport, registration));
        }

        let analyzer = Self {
            backends: backends.into_boxed_slice(),
            extensions: extensions.into_boxed_slice(),
            initialization_stubs: initialization_stubs.into_boxed_slice(),
            trace_enabled,
            telemetry: ExternalAnalyzerTelemetry::default(),
            started_at,
        };

        if let Some(start) = started_at {
            let total = |count: fn(&Registration) -> usize| {
                analyzer.backends.iter().map(|backend| count(&backend.registration)).sum::<usize>()
            };

            tracing::trace!(
                backends = analyzer.backends.len(),
                extensions = analyzer.extensions.len(),
                plugins = analyzer.extensions.iter().map(|extension| extension.plugins.len()).sum::<usize>(),
                function_providers = total(|registration| registration.function_providers.len()),
                method_providers = total(|registration| registration.method_providers.len()),
                property_providers = total(|registration| registration.property_providers.len()),
                property_initialization_providers =
                    total(|registration| registration.property_initialization_providers.len()),
                class_initializer_providers = total(|registration| registration.class_initializer_providers.len()),
                entry_points = total(|registration| registration.entry_points.len()),
                attributed_entry_points = total(|registration| registration.attributed_entry_points.len()),
                issue_filter_hooks = total(|registration| registration.issue_filter_hooks.len()),
                node_analysis_hooks = total(|registration| registration.node_analysis_hooks.len()),
                method_call_analysis_hooks = total(|registration| registration.method_call_analysis_hooks.len()),
                class_like_analysis_hooks = total(|registration| registration.class_like_analysis_hooks.len()),
                before_analysis_plugins = total(|registration| registration.before_analysis_plugins.len()),
                after_file_analysis_plugins = total(|registration| registration.after_file_analysis_plugins.len()),
                after_analysis_plugins = total(|registration| registration.after_analysis_plugins.len()),
                elapsed = ?start.elapsed(),
                "External analyzer initialized."
            );
        }

        Ok(analyzer)
    }
}

impl<T> Drop for ExternalAnalyzer<T> {
    fn drop(&mut self) {
        if !self.trace_enabled {
            return;
        }

        let function_lookups = self.telemetry.function_lookups.load(Ordering::Relaxed);
        let method_lookups = self.telemetry.method_lookups.load(Ordering::Relaxed);
        let property_lookups = self.telemetry.property_lookups.load(Ordering::Relaxed);
        let property_initialization_lookups = self.telemetry.property_initialization_lookups.load(Ordering::Relaxed);
        let class_initializer_lookups = self.telemetry.class_initializer_lookups.load(Ordering::Relaxed);
        let signature_lookups = self.telemetry.signature_lookups.load(Ordering::Relaxed);
        let assertion_lookups = self.telemetry.assertion_lookups.load(Ordering::Relaxed);
        let lookups = function_lookups
            .saturating_add(method_lookups)
            .saturating_add(property_lookups)
            .saturating_add(property_initialization_lookups)
            .saturating_add(class_initializer_lookups)
            .saturating_add(signature_lookups)
            .saturating_add(assertion_lookups);
        let requests = self.telemetry.requests.load(Ordering::Relaxed);
        let ipc_requests = self.telemetry.ipc_requests.load(Ordering::Relaxed);
        let nested_requests = self.telemetry.nested_requests.load(Ordering::Relaxed);
        let comparison_batches = self.telemetry.comparison_batches.load(Ordering::Relaxed);
        let comparisons = self.telemetry.comparisons.load(Ordering::Relaxed);
        let metadata_queries = self.telemetry.metadata_queries.load(Ordering::Relaxed);
        let analysis_queries = self.telemetry.analysis_queries.load(Ordering::Relaxed);
        let symbol_reference_queries = self.telemetry.symbol_reference_queries.load(Ordering::Relaxed);
        let lifecycle_requests = self
            .telemetry
            .before_analysis_requests
            .load(Ordering::Relaxed)
            .saturating_add(self.telemetry.after_file_analysis_requests.load(Ordering::Relaxed))
            .saturating_add(self.telemetry.after_analysis_requests.load(Ordering::Relaxed));
        tracing::trace!(
            function_lookups,
            method_lookups,
            property_lookups,
            property_initialization_lookups,
            class_initializer_lookups,
            signature_lookups,
            assertion_lookups,
            backend_checks = self.telemetry.backend_checks.load(Ordering::Relaxed),
            candidate_providers = self.telemetry.candidate_providers.load(Ordering::Relaxed),
            matched_providers = self.telemetry.matched_providers.load(Ordering::Relaxed),
            unmatched_lookups = self.telemetry.unmatched_lookups.load(Ordering::Relaxed),
            "External analyzer matching summary."
        );
        tracing::trace!(
            requests,
            ipc_requests,
            provider_cache_hits = self.telemetry.provider_cache_hits.load(Ordering::Relaxed),
            signature_requests = self.telemetry.signature_requests.load(Ordering::Relaxed),
            assertion_requests = self.telemetry.assertion_requests.load(Ordering::Relaxed),
            provided_types = self.telemetry.provided_types.load(Ordering::Relaxed),
            initialized_properties = self.telemetry.initialized_properties.load(Ordering::Relaxed),
            provided_class_initializers = self.telemetry.provided_class_initializers.load(Ordering::Relaxed),
            provided_signatures = self.telemetry.provided_signatures.load(Ordering::Relaxed),
            provided_assertions = self.telemetry.provided_assertions.load(Ordering::Relaxed),
            declined_requests = self.telemetry.declined_requests.load(Ordering::Relaxed),
            errors = self.telemetry.errors.load(Ordering::Relaxed),
            arguments = self.telemetry.arguments.load(Ordering::Relaxed),
            typed_arguments = self.telemetry.typed_arguments.load(Ordering::Relaxed),
            snapshotted_types = self.telemetry.snapshotted_types.load(Ordering::Relaxed),
            request_bytes = self.telemetry.request_bytes.load(Ordering::Relaxed),
            response_bytes = self.telemetry.response_bytes.load(Ordering::Relaxed),
            "External analyzer provider summary."
        );

        tracing::trace!(
            nested_requests,
            nested_errors = self.telemetry.nested_errors.load(Ordering::Relaxed),
            nested_request_bytes = self.telemetry.nested_request_bytes.load(Ordering::Relaxed),
            nested_response_bytes = self.telemetry.nested_response_bytes.load(Ordering::Relaxed),
            comparison_batches,
            comparisons,
            metadata_queries,
            analysis_queries,
            symbol_reference_queries,
            "External analyzer nested-query summary."
        );

        tracing::trace!(
            before_analysis_requests = self.telemetry.before_analysis_requests.load(Ordering::Relaxed),
            after_file_analysis_requests = self.telemetry.after_file_analysis_requests.load(Ordering::Relaxed),
            after_file_analysis_files = self.telemetry.after_file_analysis_files.load(Ordering::Relaxed),
            after_analysis_requests = self.telemetry.after_analysis_requests.load(Ordering::Relaxed),
            lifecycle_plugins = self.telemetry.lifecycle_plugins.load(Ordering::Relaxed),
            lifecycle_issues = self.telemetry.lifecycle_issues.load(Ordering::Relaxed),
            lifecycle_errors = self.telemetry.lifecycle_errors.load(Ordering::Relaxed),
            lifecycle_request_bytes = self.telemetry.lifecycle_request_bytes.load(Ordering::Relaxed),
            lifecycle_response_bytes = self.telemetry.lifecycle_response_bytes.load(Ordering::Relaxed),
            "External analyzer lifecycle summary."
        );

        let issue_filter_batches = self.telemetry.issue_filter_batches.load(Ordering::Relaxed);
        tracing::trace!(
            issue_filter_batches,
            candidates = self.telemetry.issue_filter_candidates.load(Ordering::Relaxed),
            removed = self.telemetry.issue_filter_removed.load(Ordering::Relaxed),
            errors = self.telemetry.issue_filter_errors.load(Ordering::Relaxed),
            request_bytes = self.telemetry.issue_filter_request_bytes.load(Ordering::Relaxed),
            response_bytes = self.telemetry.issue_filter_response_bytes.load(Ordering::Relaxed),
            "External analyzer issue-filter summary."
        );

        tracing::trace!(
            matching_ms = nanos_millis(self.telemetry.matching_ns.load(Ordering::Relaxed)),
            encode_ms = nanos_millis(self.telemetry.encode_ns.load(Ordering::Relaxed)),
            type_snapshot_ms = nanos_millis(self.telemetry.type_snapshot_ns.load(Ordering::Relaxed)),
            ipc_ms = nanos_millis(self.telemetry.ipc_ns.load(Ordering::Relaxed)),
            comparison_ms = nanos_millis(self.telemetry.comparison_ns.load(Ordering::Relaxed)),
            metadata_query_ms = nanos_millis(self.telemetry.metadata_query_ns.load(Ordering::Relaxed)),
            analysis_query_ms = nanos_millis(self.telemetry.analysis_query_ns.load(Ordering::Relaxed)),
            symbol_reference_query_ms = nanos_millis(
                self.telemetry.symbol_reference_query_ns.load(Ordering::Relaxed),
            ),
            nested_query_ms = nanos_millis(self.telemetry.nested_ns.load(Ordering::Relaxed)),
            decode_ms = nanos_millis(self.telemetry.decode_ns.load(Ordering::Relaxed)),
            total_worker_cpu_ms = nanos_millis(self.telemetry.lookup_ns.load(Ordering::Relaxed)),
            average_lookup_micros = average_micros(self.telemetry.lookup_ns.load(Ordering::Relaxed), lookups),
            average_request_micros = average_micros(self.telemetry.ipc_ns.load(Ordering::Relaxed), ipc_requests),
            average_comparison_micros = average_micros(
                self.telemetry.comparison_ns.load(Ordering::Relaxed),
                comparisons,
            ),
            average_metadata_query_micros = average_micros(
                self.telemetry.metadata_query_ns.load(Ordering::Relaxed),
                metadata_queries,
            ),
            average_analysis_query_micros = average_micros(
                self.telemetry.analysis_query_ns.load(Ordering::Relaxed),
                analysis_queries,
            ),
            average_symbol_reference_query_micros = average_micros(
                self.telemetry.symbol_reference_query_ns.load(Ordering::Relaxed),
                symbol_reference_queries,
            ),
            average_nested_query_micros = average_micros(
                self.telemetry.nested_ns.load(Ordering::Relaxed),
                nested_requests,
            ),
            lifetime = ?self.started_at.map(|start| start.elapsed()).unwrap_or_default(),
            "External analyzer timing summary."
        );

        tracing::trace!(
            lifecycle_encode_ms = nanos_millis(self.telemetry.lifecycle_encode_ns.load(Ordering::Relaxed)),
            lifecycle_ipc_ms = nanos_millis(self.telemetry.lifecycle_ipc_ns.load(Ordering::Relaxed)),
            lifecycle_decode_ms = nanos_millis(self.telemetry.lifecycle_decode_ns.load(Ordering::Relaxed)),
            lifecycle_worker_cpu_ms = nanos_millis(self.telemetry.lifecycle_ns.load(Ordering::Relaxed)),
            average_lifecycle_request_micros =
                average_micros(self.telemetry.lifecycle_ns.load(Ordering::Relaxed), lifecycle_requests,),
            "External analyzer lifecycle timing summary."
        );

        tracing::trace!(
            issue_filter_encode_ms = nanos_millis(self.telemetry.issue_filter_encode_ns.load(Ordering::Relaxed)),
            issue_filter_ipc_ms = nanos_millis(self.telemetry.issue_filter_ipc_ns.load(Ordering::Relaxed)),
            issue_filter_decode_ms = nanos_millis(self.telemetry.issue_filter_decode_ns.load(Ordering::Relaxed)),
            issue_filter_worker_cpu_ms = nanos_millis(self.telemetry.issue_filter_ns.load(Ordering::Relaxed)),
            average_issue_filter_batch_micros =
                average_micros(self.telemetry.issue_filter_ns.load(Ordering::Relaxed), issue_filter_batches),
            "External analyzer issue-filter timing summary."
        );
    }
}

fn pattern_matches(pattern: &[u8], value: &[u8]) -> bool {
    if pattern == b"*" {
        return true;
    }

    if let Some(prefix) = pattern.strip_suffix(b"*") {
        starts_with_ignore_case(value, prefix)
    } else {
        value.eq_ignore_ascii_case(pattern)
    }
}

fn class_pattern_matches(codebase: &CodebaseMetadata, pattern: &[u8], class: &[u8]) -> bool {
    pattern_matches(pattern, class) || (!pattern.contains(&b'*') && codebase.is_instance_of(class, pattern))
}

fn property_pattern_matches(pattern: &[u8], property: &[u8]) -> bool {
    if pattern == b"*" {
        return true;
    }

    if let Some(prefix) = pattern.strip_suffix(b"*") { property.starts_with(prefix) } else { property == pattern }
}

fn append_path_component(target: &mut Vec<u8>, component: &[u8]) {
    const HEX: &[u8; 16] = b"0123456789ABCDEF";

    for byte in component {
        if byte.is_ascii_alphanumeric() || matches!(byte, b'-' | b'_' | b'.') {
            target.push(*byte);
        } else {
            target.push(b'%');
            target.push(HEX[usize::from(byte >> 4)]);
            target.push(HEX[usize::from(byte & 0x0f)]);
        }
    }
}

fn duration_nanos(duration: Duration) -> u64 {
    u64::try_from(duration.as_nanos()).unwrap_or(u64::MAX)
}

#[allow(clippy::cast_precision_loss, clippy::float_arithmetic)]
fn nanos_millis(nanos: u64) -> f64 {
    nanos as f64 / 1_000_000.0
}

fn average_micros(nanos: u64, count: u64) -> u64 {
    nanos.checked_div(count).unwrap_or(0) / 1_000
}

#[cfg(test)]
#[allow(clippy::expect_used, clippy::unwrap_in_result, clippy::unwrap_used)]
mod tests {
    use std::sync::Mutex;

    use mago_codex::ttype::TType;
    use mago_codex::ttype::atomic::TAtomic;
    use mago_codex::ttype::atomic::array::TArray;
    use mago_extension::WorkerError;

    use super::*;

    #[derive(Debug)]
    struct TestTransport {
        requests: Mutex<Vec<Vec<u8>>>,
    }

    #[derive(Debug)]
    struct InitializationTransport {
        broadcasts: Mutex<usize>,
        initialization_responses: Vec<Vec<u8>>,
    }

    #[derive(Debug)]
    struct RegistrationTransport(Vec<u8>);

    impl AnalyzerTransport for TestTransport {
        fn broadcast(&self, _payload: &[u8]) -> Result<Vec<Vec<u8>>, WorkerError> {
            Ok(vec![protocol::testing::registration_response()])
        }

        fn request(&self, payload: Vec<u8>) -> Result<Vec<u8>, WorkerError> {
            self.requests.lock().unwrap().push(payload);
            Ok(protocol::testing::named_object_response("Demo\\Service"))
        }

        fn request_with_handler<H>(&self, payload: Vec<u8>, _handler: &mut H) -> Result<Vec<u8>, WorkerError>
        where
            H: WorkerRequestHandler,
        {
            self.request(payload)
        }
    }

    impl AnalyzerTransport for InitializationTransport {
        fn broadcast(&self, _payload: &[u8]) -> Result<Vec<Vec<u8>>, WorkerError> {
            let mut broadcasts = self.broadcasts.lock().unwrap();
            let responses = if *broadcasts == 0 {
                vec![protocol::testing::registration_response_with_initialization()]
            } else {
                self.initialization_responses.clone()
            };

            *broadcasts += 1;
            Ok(responses)
        }

        fn request(&self, _payload: Vec<u8>) -> Result<Vec<u8>, WorkerError> {
            unreachable!("initialization tests do not issue routed requests")
        }

        fn request_with_handler<H>(&self, _payload: Vec<u8>, _handler: &mut H) -> Result<Vec<u8>, WorkerError>
        where
            H: WorkerRequestHandler,
        {
            unreachable!("initialization tests do not issue routed requests")
        }
    }

    impl AnalyzerTransport for RegistrationTransport {
        fn broadcast(&self, _payload: &[u8]) -> Result<Vec<Vec<u8>>, WorkerError> {
            Ok(vec![self.0.clone()])
        }

        fn request(&self, _payload: Vec<u8>) -> Result<Vec<u8>, WorkerError> {
            unreachable!("registration tests do not issue routed requests")
        }

        fn request_with_handler<H>(&self, _payload: Vec<u8>, _handler: &mut H) -> Result<Vec<u8>, WorkerError>
        where
            H: WorkerRequestHandler,
        {
            unreachable!("registration tests do not issue routed requests")
        }
    }

    #[test]
    fn registration_is_decoded_and_filtered() {
        let transport = Arc::new(TestTransport { requests: Mutex::new(Vec::new()) });
        let analyzer = ExternalAnalyzer::initialize_transports([transport], PHPVersion::PHP85, &[], false)
            .expect("registration should succeed");

        assert_eq!(analyzer.extensions().len(), 1);
        assert_eq!(analyzer.extensions()[0].plugins[0].identifier, "demo");
        assert_eq!(analyzer.backends[0].registration.function_providers.len(), 1);
        assert!(analyzer.backends[0].matching_function_providers(b"demo_service", false).0.is_some());
        assert!(analyzer.backends[0].matching_function_signature_providers(b"demo_service", false).0.is_none());
    }

    #[test]
    fn exact_and_wildcard_provider_indices_preserve_registration_order() {
        let indices =
            ProviderIndices::from_exact_and_wildcards(&[1, 3], [0, 3, 4]).expect("at least one provider should match");

        assert_eq!(indices.as_slice(), &[0, 1, 3, 4]);
        assert!(ProviderIndices::from_exact_and_wildcards(&[], []).is_none());
    }

    #[test]
    fn provider_response_cache_is_scoped_to_one_analysis_generation() {
        let mut cache = ProviderResponseCache::default();
        cache.insert(1, b"request".to_vec(), b"first".to_vec());

        assert_eq!(cache.get(1, b"request"), Some(b"first".to_vec()));
        assert_eq!(cache.get(2, b"request"), None);

        cache.insert(2, b"request".to_vec(), b"second".to_vec());
        assert_eq!(cache.get(2, b"request"), Some(b"second".to_vec()));
        assert_eq!(cache.get(1, b"request"), None);
    }

    #[test]
    fn default_plugins_can_be_disabled_and_reenabled_by_alias() {
        let disabled_transport = Arc::new(TestTransport { requests: Mutex::new(Vec::new()) });
        let disabled = ExternalAnalyzer::initialize_transports([disabled_transport], PHPVersion::PHP85, &[], true)
            .expect("registration should succeed");
        assert!(disabled.backends[0].registration.function_providers.is_empty());

        let enabled_transport = Arc::new(TestTransport { requests: Mutex::new(Vec::new()) });
        let enabled = ExternalAnalyzer::initialize_transports(
            [enabled_transport],
            PHPVersion::PHP85,
            &["EXAMPLE".to_string()],
            true,
        )
        .expect("registration should succeed");
        assert_eq!(enabled.backends[0].registration.function_providers.len(), 1);
    }

    #[test]
    fn plugin_selectors_cannot_shadow_native_plugins() {
        let transport = Arc::new(RegistrationTransport(protocol::testing::registration_response_with_plugin(
            "demo/extension",
            "demo",
            &["StD"],
        )));

        let result = ExternalAnalyzer::initialize_transports([transport], PHPVersion::PHP85, &[], false);

        assert!(matches!(
            result,
            Err(ExternalAnalyzerError::DuplicatePluginSelector { selector, first, second })
                if selector == "std" && first == "stdlib" && second == "demo"
        ));
    }

    #[test]
    fn plugin_aliases_must_be_unique_across_extension_hosts() {
        let first = Arc::new(RegistrationTransport(protocol::testing::registration_response_with_plugin(
            "demo/first",
            "first",
            &["shared"],
        )));
        let second = Arc::new(RegistrationTransport(protocol::testing::registration_response_with_plugin(
            "demo/second",
            "second",
            &["SHARED"],
        )));

        let result = ExternalAnalyzer::initialize_transports([first, second], PHPVersion::PHP85, &[], false);

        assert!(matches!(
            result,
            Err(ExternalAnalyzerError::DuplicatePluginSelector { selector, first, second })
                if selector == "shared" && first == "first" && second == "second"
        ));
    }

    #[test]
    fn initialization_stubs_are_scoped_and_exposed_as_external_files() {
        let response = protocol::testing::initialization_response(b"framework.php", b"<?php class FrameworkStub {}");
        let transport = Arc::new(InitializationTransport {
            broadcasts: Mutex::new(0),
            initialization_responses: vec![response.clone(), response],
        });

        let analyzer = ExternalAnalyzer::initialize_transports([Arc::clone(&transport)], PHPVersion::PHP85, &[], false)
            .expect("initialization should succeed");

        let files = analyzer.initialization_files();
        assert_eq!(*transport.broadcasts.lock().unwrap(), 2);
        assert_eq!(files.len(), 1);
        assert_eq!(files[0].name.as_ref(), b"@mago-extension/demo%2Fextension/demo/framework.php");
        assert_eq!(files[0].contents.as_ref(), b"<?php class FrameworkStub {}");
        assert!(files[0].file_type.is_external());
        assert!(files[0].path.is_none());
    }

    #[test]
    fn initialization_requires_identical_stubs_from_every_worker() {
        let transport = Arc::new(InitializationTransport {
            broadcasts: Mutex::new(0),
            initialization_responses: vec![
                protocol::testing::initialization_response(b"framework.php", b"<?php class First {}"),
                protocol::testing::initialization_response(b"framework.php", b"<?php class Second {}"),
            ],
        });

        let result = ExternalAnalyzer::initialize_transports([transport], PHPVersion::PHP85, &[], false);

        assert!(matches!(result, Err(ExternalAnalyzerError::InconsistentInitialization)));
    }

    #[test]
    fn disabled_plugins_are_not_initialized() {
        let transport =
            Arc::new(InitializationTransport { broadcasts: Mutex::new(0), initialization_responses: Vec::new() });
        let analyzer = ExternalAnalyzer::initialize_transports([Arc::clone(&transport)], PHPVersion::PHP85, &[], true)
            .expect("registration should succeed");

        assert_eq!(*transport.broadcasts.lock().unwrap(), 1);
        assert!(analyzer.initialization_files().is_empty());
    }

    #[test]
    fn decodes_constructed_and_lossless_reference_types() {
        let named =
            protocol::decode_return_type_response(&protocol::testing::named_object_response("Demo\\Service"), |_| None)
                .expect("response should decode")
                .expect("response should be handled");
        assert_eq!(
            named.get_single_named_object().expect("type should be a named object").get_name().as_bytes(),
            b"Demo\\Service"
        );

        let original = mago_codex::ttype::get_literal_string(mago_word::word(b"hello"));
        let referenced = protocol::decode_return_type_response(&protocol::testing::reference_response(0), |slot| {
            (slot == 0).then_some(&original)
        })
        .expect("response should decode")
        .expect("response should be handled");
        assert_eq!(referenced.get_id(), original.get_id());

        let non_negative =
            protocol::decode_return_type_response(&protocol::testing::non_negative_int_response(), |_| None)
                .expect("response should decode")
                .expect("response should be handled");
        assert!(non_negative.get_single_int().expect("type should be an integer").is_non_negative());

        let non_empty =
            protocol::decode_return_type_response(&protocol::testing::non_empty_string_response(), |_| None)
                .expect("response should decode")
                .expect("response should be handled");
        assert!(non_empty.is_non_empty_string());

        let complete = protocol::decode_return_type_response(
            &protocol::testing::complete_non_empty_string_list_response(),
            |_| None,
        )
        .expect("complete response should decode")
        .expect("complete response should be handled");
        let TAtomic::Array(TArray::List(list)) = complete.get_single() else {
            panic!("complete type should be a list");
        };

        assert!(list.non_empty);
        assert!(list.element_type.is_string());
    }
}