werr

var (
	ErrNotABoolean      = NewTypeSentinel("boolean")
	ErrNotAPort         = NewTypeSentinel("port")
	ErrNotAnInputPort   = NewTypeSentinel("input port")
	ErrNotAnOutputPort  = NewTypeSentinel("output port")
	ErrNotABox          = NewTypeSentinel("box")
	ErrNotAnOpaqueValue = NewTypeSentinel("opaque value")
	ErrNotAByte         = NewTypeSentinel("byte")
	// "binary" matches the user-facing terminology used in R7RS and
	// values/value_type.go; the var name keeps "Byte" for historical
	// reasons but the message phrase tracks the rest of the codebase.
	ErrNotAByteInputPort      = NewTypeSentinel("binary input port")
	ErrNotAByteOutputPort     = NewTypeSentinel("binary output port")
	ErrNotATextualPort        = NewTypeSentinel("textual port")
	ErrStopIteration          = NewStaticError("stop iteration")
	ErrNotAPrimitive          = NewTypeSentinel("primitive")
	ErrNoSuchBinding          = NewStaticError("no such binding")
	ErrNotANumber             = NewTypeSentinel("number")
	ErrCannotCompare          = NewStaticError("cannot compare values")
	ErrNotAReal               = NewTypeSentinel("real number")
	ErrDivisionByZero         = NewStaticError("division by zero")
	ErrNotAList               = NewTypeSentinel("list")
	ErrNotACloseParen         = NewStaticError("not a close parenthesis")
	ErrWrongNumberOfArguments = NewStaticError("wrong number of arguments")
	ErrNotAMachineContext     = NewTypeSentinel("machine context")
	ErrNotAPair               = NewTypeSentinel("pair")
	ErrNotACons               = NewTypeSentinel("cons")
	ErrNotACharacter          = NewTypeSentinel("character")
	ErrNotACharSet            = NewTypeSentinel("char-set")
	ErrStackUnderflow         = NewStaticError("stack underflow")
	ErrStackOverflow          = NewStaticError("stack overflow")
	ErrNotASyntaxValue        = NewTypeSentinel("syntax value")
	ErrNotASyntaxPair         = NewTypeSentinel("syntax pair")
	ErrNotASyntaxSymbol       = NewTypeSentinel("syntax symbol")
	ErrNotASyntaxList         = NewTypeSentinel("syntax list")
	ErrNotASyntaxObject       = NewTypeSentinel("syntax object")
	ErrNotASymbol             = NewTypeSentinel("symbol")
	ErrInvalidSyntax          = NewStaticError("invalid syntax")
	// ErrIncompleteInput marks input that is a valid prefix of an expression but
	// ended before completing (unterminated string/symbol, source ending inside an
	// unclosed form). REPLs errors.Is this to decide whether to read more input.
	// Lives in werr (not internal/parser) so the tokenizer can reference it without
	// an import cycle.
	ErrIncompleteInput           = NewStaticError("incomplete input")
	ErrInvalidArgument           = NewStaticError("invalid argument")
	ErrInternal                  = NewStaticError("internal error")
	ErrDuplicateBinding          = NewStaticError("duplicate binding")
	ErrNotAClosure               = NewTypeSentinel("closure")
	ErrUnknownCharacterMnemonic  = NewStaticError("unknown character mnemonic")
	ErrNotAnInteger              = NewTypeSentinel("integer")
	ErrNotALocalEnvironmentFrame = NewTypeSentinel("local environment frame")
	ErrNotAMachineTemplate       = NewTypeSentinel("machine template")
	ErrUnexpectedNil             = NewStaticError("unexpected nil value")
	ErrUnexpectedTransformer     = NewStaticError("unexpected transformer")
	ErrNotAString                = NewTypeSentinel("string")
	ErrNotANamespace             = NewTypeSentinel("namespace")
	ErrNotAVector                = NewTypeSentinel("vector")
	ErrNotAByteVector            = NewTypeSentinel("bytevector")
	ErrNotAProcedure             = NewTypeSentinel("procedure")
	ErrNotAParameter             = NewTypeSentinel("parameter")
	// ErrComposableContinuationFromGo marks an attempt to invoke a composable
	// continuation from Go via Engine.Call; composable continuations require the
	// VM winding stack and have no Go-callable form.
	ErrComposableContinuationFromGo = NewStaticError("cannot call composable continuation from Go")
	ErrNotAStringOutputPort         = NewTypeSentinel("string output port")
	ErrNotABytevectorOutputPort     = NewTypeSentinel("bytevector output port")
	ErrNotANativeError              = NewTypeSentinel("error object")
	ErrNotARecord                   = NewTypeSentinel("record")
	ErrNotARecordType               = NewTypeSentinel("record type")
	ErrOpaqueRecord                 = NewStaticError("record type is opaque")
	ErrFileNotFound                 = NewStaticError("file not found")
	ErrFileOpen                     = NewStaticError("file open failed")
	ErrLibraryNotFound              = NewStaticError("library not found")
	ErrCircularDependency           = NewStaticError("circular library dependency")
	ErrUnexportedIdentifier         = NewStaticError("identifier not exported")

	// Threading errors
	ErrNotAThread            = NewTypeSentinel("thread")
	ErrNotAMutex             = NewTypeSentinel("mutex")
	ErrNotAConditionVariable = NewTypeSentinel("condition variable")
	ErrNotATime              = NewTypeSentinel("time")
	ErrNotAChannel           = NewTypeSentinel("channel")
	ErrNotAWaitGroup         = NewTypeSentinel("wait-group")
	ErrNotARWMutex           = NewTypeSentinel("rw-mutex")
	// "once" is pronounced /wuns/ — letter rule would give "an once", but
	// the consonant /w/ sound calls for "a". Pass-through preserves the
	// correct article.
	ErrNotAOnce                = NewTypeSentinel("a once")
	ErrNotAnAtomic             = NewTypeSentinel("atomic")
	ErrPortClosed              = NewStaticError("port is closed")
	ErrNotAHashtable           = NewTypeSentinel("hashtable")
	ErrNoCaptureContext        = NewStaticError("no capture context for expansion")
	ErrExactnessConversion     = NewStaticError("exactness conversion failed")
	ErrLossyConversion         = NewStaticError("lossy conversion")
	ErrNumericRegistry         = NewStaticError("numeric registry violation")
	ErrInvalidFormat           = NewStaticError("invalid number format")
	ErrUnknownOpCode           = NewStaticError("unknown op code")
	ErrNotAMatch               = NewTypeSentinel("match")
	ErrNotAPromptTag           = NewTypeSentinel("prompt tag")
	ErrNotAContinuationMarkSet = NewTypeSentinel("continuation mark set")
	ErrNotAContinuation        = NewTypeSentinel("continuation")
	ErrNotAnErrorContext       = NewTypeSentinel("error context")
	ErrTypeConversion          = NewStaticError("type conversion failed")
	ErrCodepointOutOfRange     = NewStaticError("codepoint out of range")
	ErrIndexOutOfRange         = NewStaticError("index out of range")
	ErrImmutableString         = NewStaticError("cannot mutate immutable string")
	ErrImmutablePair           = NewStaticError("cannot mutate immutable pair")
	ErrImmutableVector         = NewStaticError("cannot mutate immutable vector")
	ErrImmutableBytevector     = NewStaticError("cannot mutate immutable bytevector")
	ErrImmutableBinding        = NewStaticError("cannot mutate immutable binding")
	ErrInvariantViolation      = NewStaticError("invariant violation")

	// FFI errors
	ErrFFIRegistration          = NewStaticError("FFI registration error")
	ErrFFICallbackError         = NewStaticError("FFI callback error")
	ErrCallbackResultConversion = NewStaticError("callback result conversion failed")
	ErrHashtableInsertionFailed = NewStaticError("hashtable insertion failed")

	// Engine initialization errors
	ErrEngineInit = NewStaticError("engine initialization error")

	// Pipeline errors (expansion, compilation, runtime phases)
	ErrExpansion   = NewStaticError("expansion error")
	ErrCompilation = NewStaticError("compilation error")

	// Environment errors (keep as panics but use sentinels)
	ErrMissingNamespace     = NewStaticError("missing Namespace")
	ErrMissingPhaseRegistry = NewStaticError("missing PhaseRegistry")
	ErrNilParentEnvironment = NewStaticError("nil parent environment")

	// Panic recovery errors
	ErrThreadPanic   = NewStaticError("thread panic")
	ErrPanicRecovery = NewStaticError("panic recovery")

	// Syntax errors
	ErrCannotDoubleSyntaxWrap  = NewStaticError("cannot wrap syntax value in SyntaxObject")
	ErrNoMatchingClause        = NewStaticError("no matching clause")
	ErrUnsupportedTransformer  = NewStaticError("unsupported transformer")
	ErrLibraryConfiguration    = NewStaticError("library configuration error")
	ErrLibraryFormMalformed    = NewStaticError("malformed library form")
	ErrLibraryNameMismatch     = NewStaticError("library name mismatch")
	ErrHashtableKeyNotFound    = NewStaticError("hashtable key not found")
	ErrAllocationLimitExceeded = NewStaticError("allocation limit exceeded")
	ErrNonContinuableException = NewStaticError("non-continuable exception")

	// Recursion depth
	ErrCallDepthExceeded     = NewStaticError("call depth exceeded")
	ErrParseDepthExceeded    = NewStaticError("parse nesting depth exceeded")
	ErrExpandDepthExceeded   = NewStaticError("macro expansion nesting depth exceeded")
	ErrContinuationUnderflow = NewStaticError("continuation underflow")

	// Escape continuations
	ErrExpiredEscape       = NewStaticError("expired escape procedure")
	ErrContinuationBarrier = NewStaticError("continuation barrier violation")

	// Utility errors (keep as panic)
	ErrRandomGenerationFailed = NewStaticError("random generation failed")
	ErrInvalidLoadPath        = NewStaticError("invalid load path")

	// Channel errors
	ErrChannelClosed = NewStaticError("channel is closed")

	// Process errors
	ErrNotAProcess = NewTypeSentinel("process")

	// Thread errors
	ErrJoinTimeout             = NewStaticError("thread-join!: timeout")
	ErrThreadAlreadyStarted    = NewStaticError("thread-start!: thread already started")
	ErrCrossThreadContinuation = NewStaticError("cannot invoke continuation from different thread")
)