diff --git a/internal/framework/contracts/contracts.go b/internal/framework/contracts/contracts.go
new file mode 100644
index 0000000..53a4eee
--- /dev/null
+++ b/internal/framework/contracts/contracts.go
@@ -0,0 +1,97 @@
+package contracts
+
+import (
+	"context"
+	"encoding/json"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/artifacts"
+	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
+)
+
+type LLMMessage struct {
+	Role    string `json:"role"`
+	Content string `json:"content"`
+}
+
+type StructuredCompletionRequest struct {
+	StageName          string          `json:"stage_name"`
+	Messages           []LLMMessage    `json:"messages"`
+	Model              string          `json:"model,omitempty"`
+	ResponseSchemaName string          `json:"response_schema_name,omitempty"`
+	ResponseSchema     json.RawMessage `json:"response_schema,omitempty"`
+}
+
+type StructuredCompletionResponse struct {
+	Content          json.RawMessage `json:"content"`
+	Provider         string          `json:"provider,omitempty"`
+	Model            string          `json:"model,omitempty"`
+	PromptTokens     int             `json:"prompt_tokens,omitempty"`
+	CompletionTokens int             `json:"completion_tokens,omitempty"`
+	TotalTokens      int             `json:"total_tokens,omitempty"`
+}
+
+type StructuredLLMClient interface {
+	CompleteStructured(ctx context.Context, req StructuredCompletionRequest, out any) (StructuredCompletionResponse, error)
+}
+
+type ParseRequest struct {
+	SourceID string         `json:"source_id,omitempty"`
+	Path     string         `json:"path,omitempty"`
+	Raw      []byte         `json:"-"`
+	Metadata map[string]any `json:"metadata,omitempty"`
+}
+
+type InputAdapter interface {
+	Key() string
+	Parse(ctx context.Context, req ParseRequest) (*source.SourceDocument, error)
+}
+
+type ExtractionRequest struct {
+	Source    *source.SourceDocument `json:"-"`
+	LLMClient StructuredLLMClient    `json:"-"`
+	Metadata  map[string]any         `json:"metadata,omitempty"`
+}
+
+type ExtractionResult struct {
+	Candidates []artifacts.Candidate `json:"candidates,omitempty"`
+	Warnings   []Warning             `json:"warnings,omitempty"`
+}
+
+type Extractor interface {
+	Key() string
+	ArtifactType() string
+	SchemaVersion() string
+	Validators() []Validator
+	Extract(ctx context.Context, req ExtractionRequest) (ExtractionResult, error)
+}
+
+type ValidationRequest struct {
+	Source     *source.SourceDocument `json:"-"`
+	Candidates []artifacts.Candidate  `json:"candidates"`
+	Metadata   map[string]any         `json:"metadata,omitempty"`
+}
+
+type ValidationDecision struct {
+	CandidateIndex         int    `json:"candidate_index"`
+	Approved               bool   `json:"approved"`
+	ReasonCode             string `json:"reason_code"`
+	Message                string `json:"message"`
+	DiagnosticArtifactPath string `json:"diagnostic_artifact_path,omitempty"`
+}
+
+type ValidationResult struct {
+	ValidatorName string               `json:"validator_name"`
+	Decisions     []ValidationDecision `json:"decisions"`
+	Warnings      []Warning            `json:"warnings,omitempty"`
+}
+
+type Validator interface {
+	Name() string
+	Validate(ctx context.Context, req ValidationRequest) (ValidationResult, error)
+}
+
+type Warning struct {
+	Scope      string `json:"scope,omitempty"`
+	ReasonCode string `json:"reason_code"`
+	Message    string `json:"message"`
+}
diff --git a/internal/framework/contracts/contracts_test.go b/internal/framework/contracts/contracts_test.go
new file mode 100644
index 0000000..642dc80
--- /dev/null
+++ b/internal/framework/contracts/contracts_test.go
@@ -0,0 +1,165 @@
+package contracts
+
+import (
+	"context"
+	"encoding/json"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/artifacts"
+	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
+)
+
+var _ InputAdapter = fakeAdapter{}
+var _ Extractor = fakeExtractor{}
+var _ Validator = fakeValidator{}
+var _ StructuredLLMClient = fakeLLMClient{}
+
+func TestFakeExtractorReturnsCandidateAndValidator(t *testing.T) {
+	validator := fakeValidator{name: "generic-validator"}
+	extractor := fakeExtractor{
+		key:           "generic-extractor",
+		artifactType:  "generic-artifact",
+		schemaVersion: "v1",
+		validators:    []Validator{validator},
+	}
+	doc := &source.SourceDocument{
+		ID:     "source-1",
+		Kind:   "document",
+		Format: "text/plain",
+		Digest: "sha256:abc123",
+		Units: []source.SourceUnit{
+			{ID: "u1", Kind: "section", Text: "Source text."},
+		},
+	}
+
+	result, err := extractor.Extract(context.Background(), ExtractionRequest{Source: doc})
+	if err != nil {
+		t.Fatalf("Extract() error = %v, want nil", err)
+	}
+
+	if extractor.Key() != "generic-extractor" {
+		t.Fatalf("Key() = %q, want generic-extractor", extractor.Key())
+	}
+	if extractor.ArtifactType() != "generic-artifact" {
+		t.Fatalf("ArtifactType() = %q, want generic-artifact", extractor.ArtifactType())
+	}
+	if extractor.SchemaVersion() != "v1" {
+		t.Fatalf("SchemaVersion() = %q, want v1", extractor.SchemaVersion())
+	}
+	if len(extractor.Validators()) != 1 {
+		t.Fatalf("len(Validators()) = %d, want 1", len(extractor.Validators()))
+	}
+	if extractor.Validators()[0].Name() != "generic-validator" {
+		t.Fatalf("Validators()[0].Name() = %q, want generic-validator", extractor.Validators()[0].Name())
+	}
+	if len(result.Candidates) != 1 {
+		t.Fatalf("len(Candidates) = %d, want 1", len(result.Candidates))
+	}
+
+	candidate := result.Candidates[0]
+	if candidate.Index != 0 {
+		t.Fatalf("Candidate.Index = %d, want 0", candidate.Index)
+	}
+	if candidate.ExtractorKey != extractor.Key() {
+		t.Fatalf("Candidate.ExtractorKey = %q, want %q", candidate.ExtractorKey, extractor.Key())
+	}
+	if candidate.ArtifactType != extractor.ArtifactType() {
+		t.Fatalf("Candidate.ArtifactType = %q, want %q", candidate.ArtifactType, extractor.ArtifactType())
+	}
+	if candidate.SchemaVersion != extractor.SchemaVersion() {
+		t.Fatalf("Candidate.SchemaVersion = %q, want %q", candidate.SchemaVersion, extractor.SchemaVersion())
+	}
+	if string(candidate.Payload) != `{"value":"example"}` {
+		t.Fatalf("Candidate.Payload = %s, want example payload", candidate.Payload)
+	}
+}
+
+type fakeAdapter struct {
+	key string
+	doc *source.SourceDocument
+}
+
+func (adapter fakeAdapter) Key() string {
+	return adapter.key
+}
+
+func (adapter fakeAdapter) Parse(ctx context.Context, req ParseRequest) (*source.SourceDocument, error) {
+	return adapter.doc, nil
+}
+
+type fakeExtractor struct {
+	key           string
+	artifactType  string
+	schemaVersion string
+	validators    []Validator
+}
+
+func (extractor fakeExtractor) Key() string {
+	return extractor.key
+}
+
+func (extractor fakeExtractor) ArtifactType() string {
+	return extractor.artifactType
+}
+
+func (extractor fakeExtractor) SchemaVersion() string {
+	return extractor.schemaVersion
+}
+
+func (extractor fakeExtractor) Validators() []Validator {
+	return extractor.validators
+}
+
+func (extractor fakeExtractor) Extract(ctx context.Context, req ExtractionRequest) (ExtractionResult, error) {
+	return ExtractionResult{
+		Candidates: []artifacts.Candidate{
+			{
+				Index:         0,
+				ExtractorKey:  extractor.key,
+				ArtifactType:  extractor.artifactType,
+				SchemaVersion: extractor.schemaVersion,
+				Payload:       json.RawMessage(`{"value":"example"}`),
+				SourceRefs: []source.SourceRef{
+					{
+						SourceID:    req.Source.ID,
+						StartUnitID: req.Source.Units[0].ID,
+						EndUnitID:   req.Source.Units[0].ID,
+					},
+				},
+			},
+		},
+	}, nil
+}
+
+type fakeValidator struct {
+	name string
+}
+
+func (validator fakeValidator) Name() string {
+	return validator.name
+}
+
+func (validator fakeValidator) Validate(ctx context.Context, req ValidationRequest) (ValidationResult, error) {
+	decisions := make([]ValidationDecision, 0, len(req.Candidates))
+	for _, candidate := range req.Candidates {
+		decisions = append(decisions, ValidationDecision{
+			CandidateIndex: candidate.Index,
+			Approved:       true,
+			ReasonCode:     "accepted",
+			Message:        "candidate accepted",
+		})
+	}
+
+	return ValidationResult{
+		ValidatorName: validator.name,
+		Decisions:     decisions,
+	}, nil
+}
+
+type fakeLLMClient struct{}
+
+func (client fakeLLMClient) CompleteStructured(ctx context.Context, req StructuredCompletionRequest, out any) (StructuredCompletionResponse, error) {
+	return StructuredCompletionResponse{
+		Content: json.RawMessage(`{"value":"example"}`),
+	}, nil
+}