Add the conformance suite, echo fixture and integration guide

Completes FLUID-WP-0007. The seven minimal-conformance requirements and
the mechanically checkable architectural invariants are asserted as
tests rather than claimed in a README, because a conformance claim
nobody re-checks is one that quietly stops being true. Only the
checkable subset of the invariants is asserted; pretending a test can
settle the rest would be worse than leaving them to review.

TestFirstVerticalSlice runs all eleven steps of Blueprint 50 with no
human steps: two revisions, explicit routing, telemetry, a cohort
dimension, detected pressure, a hypothesis, a candidate, a 90/10
experiment, fitness comparison, promotion, and a complete audit trail.
Requests per completed task fall from 5.65 to 1.00 against a 1.20
target. A companion test runs the loop twice and requires the same
verdict, since a loop whose conclusion depended on run order would be
measuring the harness rather than the interface.

The failure-containment matrix covers Blueprint 34 directly: the data
plane keeps serving with the evidence store closed, with telemetry
wedged against a sink that never returns, after a failed build, after an
experiment rollback, and with the adaptive concurrency limit saturated.

Fixes a real bug the suite exposed. Drain closed the emitter outright,
so every request after the first flush emitted into a dead emitter and
was silently lost -- the kind of fault that makes a later measurement
quietly wrong rather than loudly broken. Emitter.Flush now waits for
delivery without stopping it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014KmVxhJ35tCo7rE7UnLwWu

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 1116572@bnt-lap001
Assistant-Session: 8ba9bb93-a72a-4883-b189-2499cce5c400

.github/workflows/ci.yml

@@ -40,3 +40,8 @@ jobs:
 
       - name: Test
         run: make test
+
+      # The conformance suite is run separately and without the cache: a
+      # conformance claim is only worth what the last full run proved.
+      - name: Conformance
+        run: make conformance

Makefile

@@ -41,8 +41,8 @@ check-generated: ## Fail if generated code is stale relative to schemas/
 	fi
 
 .PHONY: conformance
-conformance: ## Full conformance suite (grows through FLUID-WP-0007)
-	$(GO) test ./conformance/... $(PKGS)
+conformance: ## Assert every conformance requirement and architectural invariant
+	$(GO) test -count=1 ./conformance/...
 
 .PHONY: clean
 clean:

conformance/suite/conformance_test.go

@@ -0,0 +1,448 @@
+package suite
+
+import (
+	"context"
+	"crypto/ed25519"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/tegwick/fluid-core/internal/contract"
+	"github.com/tegwick/fluid-core/internal/evidence"
+	"github.com/tegwick/fluid-core/internal/publish"
+	"github.com/tegwick/fluid-core/internal/runtime"
+	"github.com/tegwick/fluid-core/internal/signing"
+)
+
+// ---------------------------------------------------------------------------
+// FluidAPIStandards.md section 36 — minimal v0.1 conformance
+//
+// An implementation claiming core conformance MUST provide all seven of these.
+// They are asserted here rather than claimed in a README, because a conformance
+// claim nobody re-checks is a conformance claim that quietly stops being true.
+// ---------------------------------------------------------------------------
+
+// 1. A deterministic API contract.
+func TestConformance01_DeterministicContract(t *testing.T) {
+	h := New(t)
+
+	// The contract is enforced, not merely declared: an undeclared path is
+	// refused rather than proxied through.
+	mustStatus(t, h.Call("c-1", http.MethodGet, "/v1/entries"), http.StatusOK, "declared path")
+	mustStatus(t, h.Call("c-1", http.MethodGet, "/v1/undeclared"), http.StatusBadRequest, "undeclared path")
+	mustStatus(t, h.Call("c-1", http.MethodDelete, "/v1/entries"), http.StatusBadRequest, "undeclared method")
+
+	// Determinism: the same request must produce the same outcome every time.
+	first := h.Call("c-1", http.MethodGet, "/v1/entries")
+	for i := 0; i < 20; i++ {
+		again := h.Call("c-1", http.MethodGet, "/v1/entries")
+		if again.Code != first.Code || again.Body.String() != first.Body.String() {
+			t.Fatal("identical requests produced different responses")
+		}
+	}
+}
+
+// 2. An identifiable active interface revision.
+func TestConformance02_IdentifiableRevision(t *testing.T) {
+	h := New(t)
+
+	rec := h.Call("c-1", http.MethodGet, "/v1/entries")
+	if got := rec.Header().Get("X-FLUID-Revision"); got != "R-1" {
+		t.Errorf("response does not identify its revision: %q", got)
+	}
+
+	// The revision that served a request must also be identifiable afterwards,
+	// from evidence rather than from the response the consumer happened to keep.
+	h.Drain()
+	for _, ev := range h.Telemetry() {
+		if ev.Revision == nil || *ev.Revision == "" {
+			t.Fatal("a telemetry event does not name the revision that served it")
+		}
+	}
+}
+
+// 3. Interface telemetry.
+func TestConformance03_Telemetry(t *testing.T) {
+	h := New(t)
+
+	for i := 0; i < 5; i++ {
+		h.Call("c-1", http.MethodGet, "/v1/entries")
+	}
+	h.Call("c-1", http.MethodGet, "/v1/undeclared")
+	h.Drain()
+
+	rows := h.Telemetry()
+	if len(rows) != 6 {
+		t.Fatalf("recorded %d telemetry events, want 6", len(rows))
+	}
+
+	var errors int
+	for _, ev := range rows {
+		if ev.Kind == contract.FluidTelemetryKindError {
+			errors++
+		}
+		if ev.Resolution == nil {
+			t.Error("an event does not record why its revision was chosen")
+		}
+	}
+	if errors != 1 {
+		t.Errorf("recorded %d error events, want 1", errors)
+	}
+}
+
+// 4. Declared interface evolutionary intent.
+func TestConformance04_DeclaredIntent(t *testing.T) {
+	h := New(t)
+	ctx := context.Background()
+
+	active, err := h.Intents.Active(ctx)
+	if err != nil {
+		t.Fatalf("no active intent: %v", err)
+	}
+	if !active.Mode.Valid() {
+		t.Errorf("active intent declares no valid authority mode")
+	}
+
+	// Every revision must be bound to the intent version governing it.
+	for _, rev := range []contract.RevisionID{"R-1", "R-2"} {
+		governing, err := h.Intents.GoverningIntent(ctx, rev)
+		if err != nil {
+			t.Errorf("%s has no governing intent: %v", rev, err)
+			continue
+		}
+		if governing.Digest == "" {
+			t.Errorf("%s is bound to an intent with no digest", rev)
+		}
+	}
+}
+
+// 5. An auditable link from evidence to proposed change.
+func TestConformance05_EvidenceToChangeIsAuditable(t *testing.T) {
+	h := New(t)
+	ctx := context.Background()
+
+	loop := RunFullLoop(t, h)
+
+	// Pressure -> hypothesis -> revision -> experiment -> decision must be
+	// traversable without guessing.
+	pressure, err := h.Store.Record(ctx, contract.KindPressure, string(loop.Pressure))
+	if err != nil {
+		t.Fatalf("pressure not retrievable: %v", err)
+	}
+	if len(pressure) == 0 {
+		t.Fatal("pressure record is empty")
+	}
+
+	hyp, err := h.Hypotheses.Get(ctx, loop.Hypothesis)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(hyp.Observation.EvidenceRefs) == 0 {
+		t.Error("the hypothesis cites no evidence")
+	}
+	if len(hyp.CandidateRevisionRefs) == 0 {
+		t.Error("the hypothesis names no candidate revision")
+	}
+	if len(hyp.ExperimentRefs) == 0 {
+		t.Error("the hypothesis names no experiment")
+	}
+
+	// And the revision must carry events reaching back to the decision.
+	events := h.Events(string(loop.Candidate))
+	var sawDecision bool
+	for _, ev := range events {
+		if strings.HasPrefix(ev.EventType, "PROMOTION_DECIDED") {
+			sawDecision = true
+			if len(ev.Inputs) == 0 {
+				t.Error("the promotion decision cites no inputs")
+			}
+		}
+	}
+	if !sawDecision {
+		t.Error("no promotion decision is recorded against the candidate")
+	}
+}
+
+// 6. Explicit responsibility boundaries.
+func TestConformance06_ResponsibilityBoundaries(t *testing.T) {
+	h := New(t)
+
+	// The interface owns representation and routing; the backend owns the data.
+	// When the backend is gone, the interface must report that rather than
+	// inventing a response.
+	h.StopAdapter("R-1")
+
+	rec := h.Call("c-1", http.MethodGet, "/v1/entries")
+	if rec.Code != http.StatusBadGateway && rec.Code != http.StatusGatewayTimeout {
+		t.Fatalf("status %d; a dead backend must surface as a gateway error", rec.Code)
+	}
+	if strings.Contains(rec.Body.String(), "127.0.0.1") {
+		t.Error("the backend address leaked into the error response")
+	}
+}
+
+// 7. Deterministic security enforcement independent of probabilistic decisions.
+func TestConformance07_DeterministicSecurity(t *testing.T) {
+	h := New(t)
+
+	// An unsigned descriptor is refused by the router regardless of anything
+	// else about it.
+	unsigned := contract.Revision{
+		SchemaVersion: "0.1", ID: "R-rogue", Interface: Interface,
+		State:    contract.RevisionStateStable,
+		Contract: contract.RevisionContract{Type: contract.RevisionContractTypeOpenapi, Digest: contract.Digest("sha256:" + strings.Repeat("9", 64))},
+		Runtime:  contract.RevisionRuntime{Upstream: h.AdapterURL("R-1")},
+		Intent:   contract.RevisionIntent{Version: "IEI-1"},
+		Policy: contract.RevisionPolicy{
+			Compatibility: contract.RevisionPolicyCompatibilityAdditive,
+			SecurityCheck: contract.RevisionPolicySecurityCheckPassed,
+		},
+	}
+	if err := h.Registry.PutRevision(unsigned); err == nil {
+		t.Fatal("an unsigned descriptor was accepted by the router")
+	}
+
+	// A signed descriptor whose content was altered afterwards must also fail.
+	sig, err := h.Signer.Sign(contract.RevisionDescriptorDocument{Revision: unsigned})
+	if err != nil {
+		t.Fatal(err)
+	}
+	tampered := unsigned
+	tampered.Runtime.Upstream = "http://attacker.invalid"
+	tampered.Signature = &contract.RevisionSignature{
+		Algorithm: contract.RevisionSignatureAlgorithm(sig.Algorithm),
+		KeyID:     sig.KeyID, Value: sig.Value,
+	}
+	if err := h.Registry.PutRevision(tampered); err == nil {
+		t.Fatal("a tampered descriptor was accepted by the router")
+	}
+}
+
+// ---------------------------------------------------------------------------
+// ArchitectureBlueprint.md section 55 — architectural invariants
+//
+// Only the mechanically checkable subset is asserted. The rest are design
+// properties a test cannot settle, and pretending otherwise would be worse
+// than leaving them to review.
+// ---------------------------------------------------------------------------
+
+// Invariant 1: runtime behaviour remains deterministic.
+// Invariant 2: evolution can stop without stopping the API.
+func TestInvariant02_EvolutionCanStopWithoutStoppingTheAPI(t *testing.T) {
+	h := New(t)
+
+	// Kill the entire observation and control plane: telemetry delivery first,
+	// then the evidence store itself.
+	h.Drain()
+	if err := h.Store.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	// The data plane must keep serving from cached published configuration.
+	for i := 0; i < 10; i++ {
+		rec := h.Call("c-1", http.MethodGet, "/v1/entries")
+		if rec.Code != http.StatusOK {
+			t.Fatalf("request %d returned %d after the control plane died", i, rec.Code)
+		}
+	}
+}
+
+// Invariant 3: every published revision is identifiable.
+// Invariant 4: every revision has an explicit contract.
+// Invariant 5: every revision is governed by a specific intent version.
+func TestInvariant03to05_RevisionIdentityContractAndIntent(t *testing.T) {
+	h := New(t)
+	ctx := context.Background()
+
+	for _, id := range []contract.RevisionID{"R-1", "R-2"} {
+		d, err := h.Registry.Revision(id)
+		if err != nil {
+			t.Fatalf("%s is not registered: %v", id, err)
+		}
+		if d.ID == "" {
+			t.Errorf("%s has no identity", id)
+		}
+		if d.Contract.Digest == "" {
+			t.Errorf("%s has no contract digest", id)
+		}
+		if _, ok := h.Validator.Contract(d.Contract.Digest); !ok {
+			t.Errorf("%s names a contract the gateway cannot enforce", id)
+		}
+		if d.Intent.Version == "" {
+			t.Errorf("%s declares no governing intent", id)
+		}
+		if _, err := h.Intents.GoverningIntent(ctx, id); err != nil {
+			t.Errorf("%s has no recorded intent binding: %v", id, err)
+		}
+	}
+}
+
+// Invariant 7: every experiment has guardrails and stop conditions.
+func TestInvariant07_ExperimentsAreBounded(t *testing.T) {
+	h := New(t)
+	ctx := context.Background()
+
+	unbounded := contract.FluidExperiment{
+		ID: "E-unbounded", HypothesisRefs: []contract.HypothesisID{"H-1"},
+		ControlRevision: "R-1", CandidateRevisions: []contract.RevisionID{"R-2"},
+		Allocation: map[string]contract.UnitInterval{"control": 0.9, "candidate": 0.1},
+		Metrics:    contract.FluidExperimentMetrics{Primary: []string{"m"}},
+		// No stop conditions.
+	}
+	if _, err := h.Experiments.Design(ctx, unbounded, Operator); err == nil {
+		t.Error("an experiment with no stop condition was designed")
+	}
+}
+
+// Invariant 8: every promotion is auditable.
+// Invariant 9: AI-generated artifacts are untrusted until verified.
+func TestInvariant09_GeneratedArtifactsAreUntrustedUntilVerified(t *testing.T) {
+	h := New(t)
+
+	// A candidate that has not been through the pipeline cannot be published:
+	// Publish takes a Verified value and nothing else constructs one.
+	if err := h.Pipeline.Publish(context.Background(), publish.Verified{}); err == nil {
+		t.Fatal("an unverified value was published")
+	}
+}
+
+// Invariant 10: security policy remains deterministic.
+func TestInvariant10_SecurityPolicyIsDeterministic(t *testing.T) {
+	h := New(t)
+
+	// The same descriptor must be judged identically every time.
+	d, err := h.Registry.Revision("R-1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	first := h.Registry.CheckRoutable("R-1", "agents")
+	for i := 0; i < 50; i++ {
+		if got := h.Registry.CheckRoutable("R-1", "agents"); (got == nil) != (first == nil) {
+			t.Fatal("routability judgement varied between identical calls")
+		}
+	}
+	_ = d
+}
+
+// Invariant 13: multiple revisions may coexist.
+func TestInvariant13_RevisionsCoexist(t *testing.T) {
+	h := New(t)
+
+	// Both revisions serve concurrently, distinguished only by resolution.
+	mustStatus(t, h.CallPinned("c-1", "R-1", http.MethodGet, "/v1/entries"), http.StatusOK, "R-1")
+	mustStatus(t, h.CallPinned("c-2", "R-2", http.MethodGet, "/v1/entries/latest"), http.StatusOK, "R-2 latest")
+
+	// And the convenience resource exists only in R-2, which is what makes the
+	// two revisions genuinely different contracts rather than a relabelling.
+	mustStatus(t, h.CallPinned("c-3", "R-1", http.MethodGet, "/v1/entries/latest"),
+		http.StatusBadRequest, "R-1 must not serve a path it does not declare")
+}
+
+// Invariant 14: failed experiments are normal and recoverable.
+func TestInvariant14_FailedExperimentsAreRecoverable(t *testing.T) {
+	h := New(t)
+	ctx := context.Background()
+
+	loop := SeedHypothesis(t, h)
+	exp := DesignExperiment(t, h, loop.Hypothesis)
+
+	if _, _, err := h.Experiments.Start(ctx, exp, 2, "R-1", Operator); err != nil {
+		t.Fatal(err)
+	}
+
+	// Stopping returns a policy with no rules; installing it puts every
+	// consumer back on the known-good revision.
+	_, stopPolicy, err := h.Experiments.Stop(ctx, exp, 3, "R-1", Operator, "guardrail breached")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(stopPolicy.Rules) != 0 {
+		t.Fatalf("the stop policy still carries %d rules", len(stopPolicy.Rules))
+	}
+	if err := h.Registry.PutPolicy(stopPolicy); err != nil {
+		t.Fatal(err)
+	}
+
+	for i := 0; i < 5; i++ {
+		rec := h.Call("c-1", http.MethodGet, "/v1/entries")
+		mustStatus(t, rec, http.StatusOK, "after rollback")
+		if got := rec.Header().Get("X-FLUID-Revision"); got != "R-1" {
+			t.Fatalf("traffic did not return to the control revision: %q", got)
+		}
+	}
+}
+
+// Invariant 16: adaptive cost is controlled independently of runtime
+// availability. Exhausting the adaptive budget must not affect serving.
+func TestInvariant16_AdaptiveBudgetDoesNotAffectRuntime(t *testing.T) {
+	h := New(t)
+	ctx := context.Background()
+
+	// Saturate the experiment concurrency limit, the framework's current
+	// expression of an adaptive budget.
+	h.Experiments.SetMaxParallel(1)
+	loop := SeedHypothesis(t, h)
+	first := DesignExperiment(t, h, loop.Hypothesis)
+	if _, _, err := h.Experiments.Start(ctx, first, 2, "R-1", Operator); err != nil {
+		t.Fatal(err)
+	}
+	second := DesignExperimentNamed(t, h, loop.Hypothesis, "E-second")
+	if _, _, err := h.Experiments.Start(ctx, second, 3, "R-1", Operator); err == nil {
+		t.Fatal("the concurrency limit did not bind")
+	}
+
+	// With adaptation blocked, the runtime is unaffected.
+	for i := 0; i < 5; i++ {
+		mustStatus(t, h.Call("c-1", http.MethodGet, "/v1/entries"), http.StatusOK,
+			"serving with the adaptive budget exhausted")
+	}
+}
+
+// TestSignedDescriptorsRoundTrip guards the property the whole trust chain
+// rests on: what the pipeline signs is what the router verifies.
+func TestSignedDescriptorsRoundTrip(t *testing.T) {
+	h := New(t)
+
+	d, err := h.Registry.Revision("R-2")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if d.Signature == nil {
+		t.Fatal("a registered revision carries no signature")
+	}
+
+	// The registry already verified this on insert; re-verifying here confirms
+	// the signature travelled with the descriptor rather than being dropped.
+	verifier := signing.NewVerifier(map[string]ed25519.PublicKey{"conformance-key": h.PublicKey})
+	if err := verifier.Verify(contract.RevisionDescriptorDocument{Revision: d}, &signing.Signature{
+		Algorithm: string(d.Signature.Algorithm),
+		KeyID:     d.Signature.KeyID,
+		Value:     d.Signature.Value,
+	}); err != nil {
+		t.Fatalf("a registered descriptor does not verify: %v", err)
+	}
+	if d.Signature.Algorithm != contract.RevisionSignatureAlgorithmEd25519 {
+		t.Errorf("unexpected signature algorithm %q", d.Signature.Algorithm)
+	}
+}
+
+// TestTelemetryCarriesNoRawIdentity is the privacy boundary at the seam that
+// matters: whatever a consumer sends, the store must not keep it.
+func TestTelemetryCarriesNoRawIdentity(t *testing.T) {
+	h := New(t)
+
+	h.Call("bernd@example.com", http.MethodGet, "/v1/entries")
+	h.Drain()
+
+	for _, ev := range h.Telemetry() {
+		if strings.Contains(ev.ConsumerRef, "@") {
+			t.Fatalf("a raw consumer identity reached the store: %q", ev.ConsumerRef)
+		}
+		if ev.Redaction == nil {
+			t.Error("an event does not record its redaction status")
+		}
+	}
+}
+
+var _ = evidence.EventFilter{}
+var _ = runtime.Request{}

conformance/suite/containment_test.go

@@ -0,0 +1,236 @@
+package suite
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/tegwick/fluid-core/internal/contract"
+	"github.com/tegwick/fluid-core/internal/publish"
+	"github.com/tegwick/fluid-core/internal/runtime"
+)
+
+// ---------------------------------------------------------------------------
+// ArchitectureBlueprint.md section 34 — failure containment
+//
+// FLUID must be designed so evolutionary failure does not imply runtime
+// failure. Each subsection names an effect and a runtime effect; the runtime
+// effect is almost always "none", and these tests are what keep that true.
+// ---------------------------------------------------------------------------
+
+// 34.1 Daimon failure: no new hypotheses or adaptations. Runtime effect: none.
+//
+// There is no Daimon yet, so the closest analogue is the whole science layer
+// being unable to record anything.
+func TestContainment_ScienceLayerFailure(t *testing.T) {
+	h := New(t)
+	ctx := context.Background()
+
+	h.Drain()
+	if err := h.Store.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Adaptation is now impossible.
+	if _, err := h.Hypotheses.List(ctx, ""); err == nil {
+		t.Log("note: hypothesis listing still succeeded; the store may be cached")
+	}
+
+	// The runtime is unaffected.
+	for i := 0; i < 10; i++ {
+		mustStatus(t, h.Call("c-1", http.MethodGet, "/v1/entries"), http.StatusOK,
+			"serving with the science layer dead")
+	}
+}
+
+// 34.2 Telemetry pipeline failure: reduced learning. Runtime effect: none.
+//
+// Telemetry backpressure MUST NOT block normal API requests.
+func TestContainment_TelemetryBackpressure(t *testing.T) {
+	stalled := &stallingSink{}
+	h := New(t)
+
+	// Replace the emitter with one writing into a sink that never completes.
+	h.Emitter.Close()
+	h.Emitter = runtime.NewEmitter(stalled, runtime.EmitterOptions{
+		Buffer: 4, Workers: 1, WriteTimeout: time.Hour,
+	})
+
+	gw, err := runtime.NewGateway(runtime.GatewayOptions{
+		Interface: Interface,
+		Registry:  h.Registry,
+		Resolver:  runtime.NewResolver(h.Registry, true),
+		Connector: runtime.NewConnector(),
+		Emitter:   h.Emitter,
+		Cohorts:   runtime.StaticCohort("agents"),
+		Validator: h.Validator,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	h.Gateway = gw
+
+	// Far more requests than the buffer can hold, against a sink that never
+	// drains. Latency must stay flat.
+	start := time.Now()
+	for i := 0; i < 200; i++ {
+		mustStatus(t, h.Call("c-1", http.MethodGet, "/v1/entries"), http.StatusOK,
+			"serving under telemetry backpressure")
+	}
+	elapsed := time.Since(start)
+
+	if elapsed > 10*time.Second {
+		t.Fatalf("200 requests took %s under telemetry backpressure; the request path is coupled to the sink", elapsed)
+	}
+	if h.Emitter.Stats().Dropped == 0 {
+		t.Error("expected telemetry to be dropped rather than queued without bound")
+	}
+}
+
+// 34.3 Builder failure: candidate not produced. Runtime effect: none.
+func TestContainment_BuilderFailure(t *testing.T) {
+	h := New(t)
+
+	// A candidate that fails verification is never published, and the running
+	// interface does not notice.
+	bad := contract.Revision{
+		SchemaVersion: "0.1", ID: "R-bad", Interface: Interface,
+		State:    contract.RevisionStateStable,
+		Contract: contract.RevisionContract{Type: contract.RevisionContractTypeOpenapi, Digest: contract.Digest("sha256:" + repeat("3", 64))},
+		Runtime:  contract.RevisionRuntime{Upstream: h.AdapterURL("R-1")},
+		Intent:   contract.RevisionIntent{Version: "IEI-1"},
+		Policy: contract.RevisionPolicy{
+			Compatibility: contract.RevisionPolicyCompatibilityBreaking,
+			SecurityCheck: contract.RevisionPolicySecurityCheckFailed,
+		},
+	}
+	if _, _, err := h.Pipeline.Run(context.Background(),
+		publish.NewCandidate(bad, Operator), publish.PromotionRequest{
+			AdaptationClasses:     []contract.AdaptationClass{contract.AdaptationClassPresentation},
+			RequestedTrafficShare: 0.1,
+			Approved:              true,
+			ApprovedBy:            &Operator,
+		}); err == nil {
+		t.Fatal("a candidate failing security passed verification")
+	}
+
+	for i := 0; i < 5; i++ {
+		mustStatus(t, h.Call("c-1", http.MethodGet, "/v1/entries"), http.StatusOK,
+			"serving after a failed build")
+	}
+}
+
+// 34.5 Experiment failure: candidate traffic removed. Runtime response: route
+// to a known-good revision.
+func TestContainment_ExperimentFailure(t *testing.T) {
+	h := New(t)
+	ctx := context.Background()
+
+	loop := SeedHypothesis(t, h)
+	exp := DesignExperiment(t, h, loop.Hypothesis)
+
+	_, startPolicy, err := h.Experiments.Start(ctx, exp, 2, "R-1", Operator)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := h.Registry.PutPolicy(startPolicy); err != nil {
+		t.Fatal(err)
+	}
+
+	// The candidate's adapter dies mid-experiment.
+	h.StopAdapter("R-2")
+
+	// Stopping the experiment restores service for everyone, including
+	// consumers that had been allocated to the broken arm.
+	_, stopPolicy, err := h.Experiments.Stop(ctx, exp, 3, "R-1", Operator, "candidate adapter unreachable")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := h.Registry.PutPolicy(stopPolicy); err != nil {
+		t.Fatal(err)
+	}
+
+	for i := 0; i < 20; i++ {
+		rec := h.Call(consumerName(i), http.MethodGet, "/v1/entries")
+		mustStatus(t, rec, http.StatusOK, "serving after experiment rollback")
+		if got := rec.Header().Get("X-FLUID-Revision"); got != "R-1" {
+			t.Fatalf("consumer %d still routed to %q after rollback", i, got)
+		}
+	}
+}
+
+// 34.6 Evolution store failure: runtime MUST continue using cached published
+// revision configuration.
+func TestContainment_EvidenceStoreFailure(t *testing.T) {
+	h := New(t)
+
+	h.Drain()
+	if err := h.Store.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Reads and writes to the store now fail.
+	if _, err := h.Store.Records(context.Background(), contract.KindRevision); err == nil {
+		t.Error("the evidence store still answers after being closed")
+	}
+
+	// The registry holds its own cached view, so routing is unaffected.
+	for i := 0; i < 10; i++ {
+		rec := h.Call("c-1", http.MethodGet, "/v1/entries")
+		mustStatus(t, rec, http.StatusOK, "serving from cached configuration")
+		if rec.Header().Get("X-FLUID-Revision") != "R-1" {
+			t.Fatal("routing changed after the evidence store died")
+		}
+	}
+}
+
+// 34.7 AI budget exhaustion: adaptive processes pause. Runtime effect: none.
+//
+// Covered by TestInvariant16_AdaptiveBudgetDoesNotAffectRuntime; this asserts
+// the complementary direction, that a saturated adaptive layer cannot make the
+// data plane refuse work.
+func TestContainment_AdaptiveSaturation(t *testing.T) {
+	h := New(t)
+	ctx := context.Background()
+
+	h.Experiments.SetMaxParallel(1)
+	loop := SeedHypothesis(t, h)
+	first := DesignExperiment(t, h, loop.Hypothesis)
+	if _, _, err := h.Experiments.Start(ctx, first, 2, "R-1", Operator); err != nil {
+		t.Fatal(err)
+	}
+
+	second := DesignExperimentNamed(t, h, loop.Hypothesis, "E-blocked")
+	_, _, err := h.Experiments.Start(ctx, second, 3, "R-1", Operator)
+	if err == nil {
+		t.Fatal("the adaptive limit did not bind")
+	}
+
+	for i := 0; i < 10; i++ {
+		mustStatus(t, h.Call("c-1", http.MethodGet, "/v1/entries"), http.StatusOK,
+			"serving with adaptation saturated")
+	}
+	_ = errors.Is
+}
+
+// stallingSink never returns, standing in for a wedged evidence store.
+type stallingSink struct{}
+
+func (s *stallingSink) Write(ctx context.Context, _ contract.FluidTelemetry) error {
+	<-ctx.Done()
+	return ctx.Err()
+}
+
+func repeat(s string, n int) string {
+	out := make([]byte, 0, n*len(s))
+	for i := 0; i < n; i++ {
+		out = append(out, s...)
+	}
+	return string(out)
+}
+
+func consumerName(i int) string {
+	return "consumer-" + string(rune('a'+i%26))
+}

conformance/suite/harness.go

@@ -0,0 +1,310 @@
+// Package suite is the FLUID conformance harness.
+//
+// It asserts the seven minimal-conformance requirements of
+// FluidAPIStandards.md section 36 and the mechanically checkable subset of the
+// sixteen architectural invariants in ArchitectureBlueprint.md section 55.
+//
+// Everything here runs with no external services and no human steps. A
+// conformance claim that needed someone to run through it by hand would be a
+// claim nobody re-checks after the first time.
+package suite
+
+import (
+	"context"
+	"crypto/ed25519"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"path/filepath"
+	"testing"
+	"time"
+
+	_ "modernc.org/sqlite"
+
+	echo "github.com/tegwick/fluid-core/examples/echo-interface"
+	"github.com/tegwick/fluid-core/internal/contract"
+	"github.com/tegwick/fluid-core/internal/evidence"
+	"github.com/tegwick/fluid-core/internal/intent"
+	"github.com/tegwick/fluid-core/internal/observation"
+	"github.com/tegwick/fluid-core/internal/policy"
+	"github.com/tegwick/fluid-core/internal/publish"
+	"github.com/tegwick/fluid-core/internal/runtime"
+	"github.com/tegwick/fluid-core/internal/science"
+	"github.com/tegwick/fluid-core/internal/signing"
+	"github.com/tegwick/fluid-core/internal/validate"
+)
+
+// Interface is the fixture's interface identifier.
+const Interface contract.InterfaceID = "echo-interface"
+
+// IntentDocument is the fixture's governing intent.
+const IntentDocument = `# Interface Evolution Intent — echo-interface
+
+**Current operational authority mode:**
+FLUID-4
+
+## Mission
+Serve entries to consumers, and learn from how they ask for them.
+`
+
+// Operator is the fixture's human actor.
+var Operator = contract.Actor{Type: contract.ActorTypeHuman, ID: "conformance"}
+
+// Harness is a fully wired FLUID deployment over the echo fixture.
+type Harness struct {
+	T *testing.T
+
+	Store     *evidence.SQLStore
+	Intents   *intent.Store
+	Registry  *runtime.Registry
+	Gateway   *runtime.Gateway
+	Emitter   *runtime.Emitter
+	Ingest    *observation.Ingest
+	Pipeline  *publish.Pipeline
+	Validator *validate.OpenAPIValidator
+	Signer    *signing.Signer
+	PublicKey ed25519.PublicKey
+
+	Hypotheses  *science.HypothesisStore
+	Experiments *science.ExperimentController
+
+	adapters map[contract.RevisionID]*httptest.Server
+}
+
+// New builds a harness with both fixture revisions published and R-1 stable.
+func New(t *testing.T) *Harness {
+	t.Helper()
+	ctx := context.Background()
+
+	store, err := evidence.OpenSQLite(ctx, filepath.Join(t.TempDir(), "conformance.db"))
+	if err != nil {
+		t.Fatalf("open evidence store: %v", err)
+	}
+	t.Cleanup(func() { _ = store.Close() })
+
+	intents := intent.New(store, Interface)
+	if _, err := intents.Put(ctx, "IEI-1", IntentDocument); err != nil {
+		t.Fatalf("record intent: %v", err)
+	}
+	if err := intents.SetActive(ctx, "IEI-1"); err != nil {
+		t.Fatalf("activate intent: %v", err)
+	}
+
+	signer, pub, err := signing.GenerateKey("conformance-key")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	limits := policy.DefaultLimits()
+	// The fixture's intent grants FLUID-4, and the loop under test promotes a
+	// contract adaptation, so the fixture permits that class explicitly.
+	limits.AllowedAdaptationClasses = append(limits.AllowedAdaptationClasses,
+		contract.AdaptationClassContract)
+	limits.RequiredMode = intent.ModeExperimental
+	gate := policy.NewGate(limits)
+
+	pipeline, err := publish.New(publish.Options{
+		Gate: gate, Signer: signer, Store: store, Intents: intents,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	salt := []byte("conformance-salt-of-sufficient-length")
+	ingest, err := observation.NewIngest(store, Interface, observation.DefaultRedactionPolicy(salt))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	h := &Harness{
+		T: t, Store: store, Intents: intents, Pipeline: pipeline,
+		Validator: validate.NewOpenAPIValidator(), Signer: signer, PublicKey: pub,
+		Ingest:   ingest,
+		adapters: map[contract.RevisionID]*httptest.Server{},
+	}
+
+	// A verifying registry: the router must accept only signed descriptors.
+	h.Registry = runtime.NewVerifiedRegistry(Interface,
+		signing.NewVerifier(map[string]ed25519.PublicKey{"conformance-key": pub}))
+
+	h.adapters["R-1"] = httptest.NewServer(echo.NewR1())
+	h.adapters["R-2"] = httptest.NewServer(echo.NewR2())
+	t.Cleanup(func() {
+		for _, s := range h.adapters {
+			s.Close()
+		}
+	})
+
+	h.Emitter = runtime.NewEmitter(ingest, runtime.EmitterOptions{Buffer: 8192, Workers: 2})
+
+	gw, err := runtime.NewGateway(runtime.GatewayOptions{
+		Interface: Interface,
+		Registry:  h.Registry,
+		Resolver:  runtime.NewResolver(h.Registry, true),
+		Connector: runtime.NewConnector(),
+		Emitter:   h.Emitter,
+		Cohorts:   observation.NewCohortEngine("agents", observation.DefaultRedactionPolicy(salt)),
+		Response:  runtime.ResponsePolicy{FeedbackPath: "/v1/feedback"},
+		Validator: h.Validator,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	h.Gateway = gw
+
+	h.Hypotheses = science.NewHypothesisStore(store, Interface)
+	h.Experiments = science.NewExperimentController(store, h.Hypotheses, Interface)
+
+	h.PublishRevision("R-1", "examples/echo-interface/r1.openapi.yaml", nil)
+	h.PublishRevision("R-2", "examples/echo-interface/r2.openapi.yaml",
+		[]contract.AdaptationClass{contract.AdaptationClassContract})
+	h.InstallPolicy(1, "R-1", nil)
+
+	return h
+}
+
+// PublishRevision takes a revision through the full pipeline and registers it.
+func (h *Harness) PublishRevision(id contract.RevisionID, contractPath string, classes []contract.AdaptationClass) contract.Revision {
+	h.T.Helper()
+	ctx := context.Background()
+
+	raw := readRepoFile(h.T, contractPath)
+	digest := signing.Digest(raw)
+
+	if err := h.Validator.Register(digest, raw); err != nil {
+		h.T.Fatalf("register contract for %s: %v", id, err)
+	}
+
+	pc := contract.RevisionPolicyPolicyCheckPassed
+	descriptor := contract.Revision{
+		SchemaVersion: "0.1",
+		ID:            id,
+		Interface:     Interface,
+		State:         contract.RevisionStateStable,
+		Contract: contract.RevisionContract{
+			Type:   contract.RevisionContractTypeOpenapi,
+			Digest: digest,
+			Source: contractPath,
+		},
+		Runtime: contract.RevisionRuntime{Upstream: h.adapters[id].URL},
+		Intent:  contract.RevisionIntent{Version: "IEI-1"},
+		Policy: contract.RevisionPolicy{
+			Compatibility: contract.RevisionPolicyCompatibilityAdditive,
+			SecurityCheck: contract.RevisionPolicySecurityCheckPassed,
+			PolicyCheck:   &pc,
+		},
+	}
+
+	if classes == nil {
+		classes = []contract.AdaptationClass{contract.AdaptationClassPresentation}
+	}
+
+	verified, report, err := h.Pipeline.Run(ctx, publish.NewCandidate(descriptor, Operator),
+		publish.PromotionRequest{
+			AdaptationClasses:     classes,
+			ComplexityDelta:       0.2,
+			RequestedTrafficShare: 0.2,
+			Approved:              true,
+			ApprovedBy:            &Operator,
+		})
+	if err != nil {
+		h.T.Fatalf("publish %s: %v (%+v)", id, err, report.Stages)
+	}
+	if err := h.Pipeline.Publish(ctx, verified); err != nil {
+		h.T.Fatalf("record %s: %v", id, err)
+	}
+	if err := h.Registry.PutRevision(verified.Descriptor()); err != nil {
+		h.T.Fatalf("register %s: %v", id, err)
+	}
+	return verified.Descriptor()
+}
+
+// InstallPolicy loads a routing policy into the registry.
+func (h *Harness) InstallPolicy(generation int64, defaultRevision contract.RevisionID, rules []contract.RoutingPolicyRulesItem) {
+	h.T.Helper()
+	if rules == nil {
+		rules = []contract.RoutingPolicyRulesItem{}
+	}
+	if err := h.Registry.PutPolicy(contract.RoutingPolicy{
+		SchemaVersion:   "0.1",
+		Interface:       Interface,
+		Generation:      generation,
+		DefaultRevision: defaultRevision,
+		Rules:           rules,
+	}); err != nil {
+		h.T.Fatalf("install policy generation %d: %v", generation, err)
+	}
+}
+
+// Call issues a request through the gateway as a named consumer.
+func (h *Harness) Call(consumer, method, target string) *httptest.ResponseRecorder {
+	h.T.Helper()
+	req := httptest.NewRequest(method, target, nil)
+	req.Header.Set("X-FLUID-Consumer", consumer)
+	rec := httptest.NewRecorder()
+	h.Gateway.ServeHTTP(rec, req)
+	return rec
+}
+
+// CallPinned issues a request pinned to a specific revision.
+func (h *Harness) CallPinned(consumer string, rev contract.RevisionID, method, target string) *httptest.ResponseRecorder {
+	h.T.Helper()
+	req := httptest.NewRequest(method, target, nil)
+	req.Header.Set("X-FLUID-Consumer", consumer)
+	req.Header.Set("X-FLUID-Revision", string(rev))
+	rec := httptest.NewRecorder()
+	h.Gateway.ServeHTTP(rec, req)
+	return rec
+}
+
+// Drain flushes buffered telemetry so assertions see every event.
+//
+// It flushes rather than closes: the harness keeps serving after a drain, and
+// closing here would mean every later request emitted into a dead emitter.
+func (h *Harness) Drain() {
+	if !h.Emitter.Flush(5 * time.Second) {
+		h.T.Fatal("telemetry did not reach the store within 5s")
+	}
+}
+
+// Telemetry returns everything recorded for the interface.
+func (h *Harness) Telemetry() []contract.FluidTelemetry {
+	h.T.Helper()
+	rows, err := h.Store.Telemetry(context.Background(),
+		evidence.TelemetryFilter{InterfaceID: Interface})
+	if err != nil {
+		h.T.Fatal(err)
+	}
+	return rows
+}
+
+// Events returns audit events for an entity.
+func (h *Harness) Events(entityID string) []contract.FluidEvent {
+	h.T.Helper()
+	events, err := h.Store.Events(context.Background(), evidence.EventFilter{EntityID: entityID})
+	if err != nil {
+		h.T.Fatal(err)
+	}
+	return events
+}
+
+// AdapterURL returns a fixture adapter's address.
+func (h *Harness) AdapterURL(rev contract.RevisionID) string {
+	return h.adapters[rev].URL
+}
+
+// StopAdapter kills a fixture adapter, for failure-containment tests.
+func (h *Harness) StopAdapter(rev contract.RevisionID) {
+	h.adapters[rev].Close()
+}
+
+// mustStatus fails unless the response carries the expected status.
+func mustStatus(t *testing.T, rec *httptest.ResponseRecorder, want int, context string) {
+	t.Helper()
+	if rec.Code != want {
+		t.Fatalf("%s: status %d, want %d; body %s", context, rec.Code, want, rec.Body.String())
+	}
+}
+
+var _ = fmt.Sprintf
+var _ = http.MethodGet

conformance/suite/loop.go

@@ -0,0 +1,321 @@
+package suite
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/tegwick/fluid-core/internal/contract"
+	"github.com/tegwick/fluid-core/internal/fitness"
+	"github.com/tegwick/fluid-core/internal/intent"
+	"github.com/tegwick/fluid-core/internal/observation"
+	"github.com/tegwick/fluid-core/internal/policy"
+	"github.com/tegwick/fluid-core/internal/promotion"
+	"github.com/tegwick/fluid-core/internal/science"
+)
+
+// Loop records the artifacts one pass of the adaptation loop produced.
+type Loop struct {
+	Pressure   contract.PressureID
+	Hypothesis contract.HypothesisID
+	Experiment contract.ExperimentID
+	Candidate  contract.RevisionID
+	Evaluation fitness.Evaluation
+	Decision   promotion.Decision
+}
+
+// GeneratePressure drives the traffic that makes R-1's shortcoming visible.
+//
+// Several independent consumers each fetch the whole collection repeatedly
+// within one task, which is the Blueprint section 33 shape: the interface is
+// making them assemble something it could have handed them.
+func GeneratePressure(t *testing.T, h *Harness) {
+	t.Helper()
+	for c := 0; c < 5; c++ {
+		consumer := fmt.Sprintf("agent-%d", c)
+		for chain := 0; chain < 4; chain++ {
+			for i := 0; i < 3; i++ {
+				rec := h.Call(consumer, http.MethodGet, "/v1/entries")
+				mustStatus(t, rec, http.StatusOK, "pressure traffic")
+			}
+		}
+	}
+}
+
+// DetectPressure classifies recorded telemetry and records what it finds.
+func DetectPressure(t *testing.T, h *Harness) contract.PressureID {
+	t.Helper()
+	ctx := context.Background()
+
+	classifier := observation.NewClassifier(
+		observation.DefaultClassifierOptions(), observation.NewTopologyAnalyzer())
+	findings := classifier.Classify(h.Telemetry())
+	if len(findings) == 0 {
+		t.Fatal("no pressure detected from traffic that plainly shows it")
+	}
+
+	registry := observation.NewPressureRegistry(h.Store, Interface)
+	recorded, err := registry.RecordAll(ctx, findings)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, p := range recorded {
+		if p.Class == contract.PressureClassSuccessfulButInefficientUsage {
+			return p.ID
+		}
+	}
+	t.Fatalf("inefficient usage was not among the findings: %v", recorded)
+	return ""
+}
+
+// SeedHypothesis creates and prepares a hypothesis explaining the pressure.
+func SeedHypothesis(t *testing.T, h *Harness) Loop {
+	t.Helper()
+	ctx := context.Background()
+
+	hypothesis := contract.FluidHypothesis{
+		ID:    "H-1",
+		Title: "latest entry is a first-class consumer concept",
+		Observation: contract.FluidHypothesisObservation{
+			Summary:      "consumers fetch the whole collection repeatedly to find the newest entry",
+			EvidenceRefs: []contract.EvidenceRef{"topology:GET /v1/entries"},
+		},
+		Pressure: contract.FluidHypothesisPressure{
+			Classes: []contract.PressureClass{contract.PressureClassSuccessfulButInefficientUsage},
+		},
+		Explanation: contract.FluidHypothesisExplanation{
+			Claim: "the collection resource does not name a concept consumers hold, so they assemble it themselves",
+		},
+		ProposedAdaptation: contract.FluidHypothesisProposedAdaptation{
+			Class:   contract.AdaptationClassContract,
+			Summary: "add an explicit latest-entry resource",
+		},
+		ExpectedOutcomes: []contract.ExpectedOutcome{{
+			Metric:    fitness.MetricRequestsPerTask,
+			Target:    1.2,
+			Direction: contract.ExpectedOutcomeDirectionLower,
+		}},
+		Guardrails: []contract.Guardrail{{
+			Metric: fitness.MetricErrorRate, Operator: contract.GuardrailOperatorLte, Threshold: 0.01,
+		}},
+		SuccessCriteria: contract.FluidHypothesisSuccessCriteria{
+			Expression: "requests_per_completed_task <= 1.2 with no guardrail violation",
+		},
+		Complexity: contract.FluidHypothesisComplexity{
+			ExpectedDelta: contract.ComplexityDelta{OperationCount: ptr(1.0)},
+		},
+		Risk: contract.FluidHypothesisRisk{Level: contract.FluidHypothesisRiskLevelLOW},
+	}
+
+	if _, err := h.Hypotheses.Create(ctx, hypothesis, Operator); err != nil {
+		t.Fatal(err)
+	}
+	for _, s := range []contract.FluidHypothesisState{
+		contract.FluidHypothesisStateREADY,
+		contract.FluidHypothesisStatePRIORITIZED,
+		contract.FluidHypothesisStateDESIGNING,
+	} {
+		if _, err := h.Hypotheses.Transition(ctx, "H-1", s, Operator, "advancing the loop"); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := h.Hypotheses.AttachRevision(ctx, "H-1", "R-2", Operator); err != nil {
+		t.Fatal(err)
+	}
+
+	return Loop{Hypothesis: "H-1", Candidate: "R-2"}
+}
+
+// DesignExperiment creates the 90/10 experiment the Blueprint slice calls for.
+func DesignExperiment(t *testing.T, h *Harness, hypothesis contract.HypothesisID) contract.ExperimentID {
+	t.Helper()
+	return DesignExperimentNamed(t, h, hypothesis, "E-1")
+}
+
+// DesignExperimentNamed creates an experiment with a chosen id.
+func DesignExperimentNamed(t *testing.T, h *Harness, hypothesis contract.HypothesisID, id contract.ExperimentID) contract.ExperimentID {
+	t.Helper()
+	ctx := context.Background()
+
+	e := contract.FluidExperiment{
+		ID:                 id,
+		HypothesisRefs:     []contract.HypothesisID{hypothesis},
+		ControlRevision:    "R-1",
+		CandidateRevisions: []contract.RevisionID{"R-2"},
+		Cohorts:            []contract.CohortID{"agents"},
+		Allocation:         map[string]contract.UnitInterval{"control": 0.9, "candidate": 0.1},
+		Metrics: contract.FluidExperimentMetrics{
+			Primary:    []string{fitness.MetricRequestsPerTask},
+			Guardrails: []string{fitness.MetricErrorRate},
+		},
+		StopConditions: []string{"hard_guardrail_violation", "manual_stop"},
+	}
+	if _, err := h.Experiments.Design(ctx, e, Operator); err != nil {
+		t.Fatal(err)
+	}
+	return id
+}
+
+// RunFullLoop executes the complete section 50 vertical slice.
+//
+// Two deterministic revisions, explicit routing, telemetry, one cohort
+// dimension, pressure detection, a hypothesis, a candidate revision, a bounded
+// experiment, fitness comparison, promotion, and a complete audit trail — with
+// no human steps.
+func RunFullLoop(t *testing.T, h *Harness) Loop {
+	t.Helper()
+	ctx := context.Background()
+
+	// 1-3. Traffic, telemetry, pressure.
+	GeneratePressure(t, h)
+	h.Drain()
+	pressureID := DetectPressure(t, h)
+
+	// 4. Hypothesis explaining it.
+	loop := SeedHypothesis(t, h)
+	loop.Pressure = pressureID
+
+	// 5. Link the evidence to the explanation.
+	registry := observation.NewPressureRegistry(h.Store, Interface)
+	if err := registry.LinkHypothesis(ctx, pressureID, loop.Hypothesis); err != nil {
+		t.Fatal(err)
+	}
+
+	// 6. A bounded experiment, enacted through routing policy.
+	expID := DesignExperiment(t, h, loop.Hypothesis)
+	loop.Experiment = expID
+
+	_, startPolicy, err := h.Experiments.Start(ctx, expID, 2, "R-1", Operator)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := h.Registry.PutPolicy(startPolicy); err != nil {
+		t.Fatal(err)
+	}
+
+	// 7. Measure both arms. Consumers are pinned so each arm gets the shape it
+	// is meant to demonstrate; the allocation itself is exercised separately in
+	// the resolver's own tests.
+	observed := measureBothArms(t, h)
+
+	// 8. Fitness comparison against the declared criteria.
+	specs := []fitness.MetricSpec{
+		{Name: fitness.MetricRequestsPerTask, Role: fitness.RolePrimary,
+			Direction: fitness.Lower, Target: ptr(1.2)},
+		{Name: fitness.MetricErrorRate, Role: fitness.RoleGuardrail,
+			Direction: fitness.Lower, Threshold: ptr(0.01)},
+	}
+	evaluator := fitness.NewEvaluator()
+	evaluator.MinSamples = 10
+	loop.Evaluation = evaluator.Evaluate("R-1", "R-2", observed.window, specs, observed.observations)
+
+	// 9. Stop the experiment and record its conclusion.
+	_, stopPolicy, err := h.Experiments.Stop(ctx, expID, 3, "R-1", Operator, "measurement window elapsed")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := h.Registry.PutPolicy(stopPolicy); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := h.Experiments.Finalize(ctx, expID, "R-2", Operator,
+		fmt.Sprintf("fitness verdict %s", loop.Evaluation.Verdict), nil); err != nil {
+		t.Fatal(err)
+	}
+
+	// 10. Record the hypothesis outcome.
+	status := contract.FluidHypothesisOutcomeStatusREFUTED
+	if loop.Evaluation.Verdict == fitness.VerdictSucceeded {
+		status = contract.FluidHypothesisOutcomeStatusCONFIRMED
+	}
+	if _, err := h.Hypotheses.RecordOutcome(ctx, loop.Hypothesis, status,
+		fmt.Sprintf("verdict %s: %v", loop.Evaluation.Verdict, loop.Evaluation.Reasons), nil, Operator); err != nil {
+		t.Fatal(err)
+	}
+
+	// 11. Promotion, through the deterministic gate.
+	loop.Decision = decide(t, h, loop)
+	return loop
+}
+
+type measurement struct {
+	observations []fitness.Observation
+	window       fitness.Window
+}
+
+// measureBothArms drives the two revisions and derives their metrics.
+func measureBothArms(t *testing.T, h *Harness) measurement {
+	t.Helper()
+	start := time.Now().Add(-time.Hour)
+
+	// R-1: three calls per task, the shape the pressure described.
+	for c := 0; c < 12; c++ {
+		consumer := fmt.Sprintf("control-%d", c)
+		for i := 0; i < 3; i++ {
+			mustStatus(t, h.CallPinned(consumer, "R-1", http.MethodGet, "/v1/entries"),
+				http.StatusOK, "control arm")
+		}
+	}
+	// R-2: one call per task, using the resource the hypothesis proposed.
+	for c := 0; c < 12; c++ {
+		consumer := fmt.Sprintf("candidate-%d", c)
+		mustStatus(t, h.CallPinned(consumer, "R-2", http.MethodGet, "/v1/entries/latest"),
+			http.StatusOK, "candidate arm")
+	}
+	h.Drain()
+
+	window := fitness.Window{Start: start}
+	return measurement{
+		observations: fitness.NewMeasurer().Measure(h.Telemetry(), window),
+		window:       window,
+	}
+}
+
+func decide(t *testing.T, h *Harness, loop Loop) promotion.Decision {
+	t.Helper()
+	ctx := context.Background()
+
+	descriptor, err := h.Registry.Revision(loop.Candidate)
+	if err != nil {
+		t.Fatal(err)
+	}
+	governing, err := h.Intents.GoverningIntent(ctx, loop.Candidate)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	limits := policy.DefaultLimits()
+	limits.AllowedAdaptationClasses = append(limits.AllowedAdaptationClasses,
+		contract.AdaptationClassContract)
+	limits.RequiredMode = intent.ModeExperimental
+
+	controller := promotion.NewController(h.Store, policy.NewGate(limits))
+	d, err := controller.Decide(ctx, promotion.Request{
+		Revision:   loop.Candidate,
+		Outcome:    promotion.Promote,
+		Reason:     "the candidate met its primary target with no guardrail breach",
+		Actor:      Operator,
+		Experiment: loop.Experiment,
+		Hypotheses: []contract.HypothesisID{loop.Hypothesis},
+		Evaluation: &loop.Evaluation,
+		GateInput: &policy.Input{
+			Descriptor:            descriptor,
+			GoverningMode:         governing.Mode,
+			AdaptationClasses:     []contract.AdaptationClass{contract.AdaptationClassContract},
+			ComplexityDelta:       0.2,
+			RequestedTrafficShare: 0.2,
+			Approved:              true,
+			ApprovedBy:            &Operator,
+		},
+	})
+	if err != nil {
+		t.Fatalf("promotion refused: %v", err)
+	}
+	return d
+}
+
+func ptr[T any](v T) *T { return &v }
+
+var _ = science.CanTransition

conformance/suite/repo.go

@@ -0,0 +1,35 @@
+package suite
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// readRepoFile reads a path relative to the repository root.
+//
+// Tests run from their own package directory, so fixture paths are resolved
+// against the module root rather than the working directory. Hard-coding
+// "../.." would break the moment the suite moved.
+func readRepoFile(t *testing.T, rel string) []byte {
+	t.Helper()
+
+	dir, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	for {
+		if _, err := os.Stat(filepath.Join(dir, "go.mod")); err == nil {
+			raw, err := os.ReadFile(filepath.Join(dir, rel))
+			if err != nil {
+				t.Fatalf("read %s: %v", rel, err)
+			}
+			return raw
+		}
+		parent := filepath.Dir(dir)
+		if parent == dir {
+			t.Fatalf("could not find the repository root above %s", dir)
+		}
+		dir = parent
+	}
+}

conformance/suite/slice_test.go

@@ -0,0 +1,222 @@
+package suite
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"github.com/tegwick/fluid-core/internal/contract"
+	"github.com/tegwick/fluid-core/internal/fitness"
+	"github.com/tegwick/fluid-core/internal/intent"
+	"github.com/tegwick/fluid-core/internal/policy"
+	"github.com/tegwick/fluid-core/internal/promotion"
+)
+
+// TestFirstVerticalSlice is the whole point of the conformance suite.
+//
+// ArchitectureBlueprint.md section 50 lists eleven things the first FLUID
+// deployment must demonstrate, and says plainly what success means:
+//
+//	The first success criterion is not autonomous coding.
+//	It is proving that the revision-experiment-fitness loop works cleanly
+//	and safely.
+//
+// This test runs all eleven with no human steps.
+func TestFirstVerticalSlice(t *testing.T) {
+	h := New(t)
+	loop := RunFullLoop(t, h)
+
+	// 1. Two deterministic revisions.
+	for _, id := range []contract.RevisionID{"R-1", "R-2"} {
+		if _, err := h.Registry.Revision(id); err != nil {
+			t.Fatalf("revision %s is not published: %v", id, err)
+		}
+	}
+
+	// 2. Explicit revision routing.
+	policy, err := h.Registry.Policy()
+	if err != nil {
+		t.Fatalf("no routing policy: %v", err)
+	}
+	if policy.DefaultRevision == "" {
+		t.Error("the routing policy names no default revision")
+	}
+
+	// 3. Telemetry.
+	telemetry := h.Telemetry()
+	if len(telemetry) == 0 {
+		t.Fatal("no telemetry recorded")
+	}
+
+	// 4. One consumer cohort dimension.
+	var sawCohort bool
+	for _, ev := range telemetry {
+		if ev.Cohort != nil && *ev.Cohort != "" {
+			sawCohort = true
+			break
+		}
+	}
+	if !sawCohort {
+		t.Error("no telemetry carries a cohort assignment")
+	}
+
+	// 5. Pressure detection.
+	if loop.Pressure == "" {
+		t.Fatal("no pressure was detected")
+	}
+
+	// 6. A hypothesis, linked to that pressure.
+	hyp, err := h.Hypotheses.Get(context.Background(), loop.Hypothesis)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if hyp.Explanation.Claim == "" {
+		t.Error("the hypothesis offers no explanation")
+	}
+
+	// 7. A candidate revision, claimed by that hypothesis.
+	var claimsCandidate bool
+	for _, r := range hyp.CandidateRevisionRefs {
+		if r == loop.Candidate {
+			claimsCandidate = true
+		}
+	}
+	if !claimsCandidate {
+		t.Errorf("the hypothesis does not claim %s", loop.Candidate)
+	}
+
+	// 8. A controlled 90/10 experiment.
+	exp, err := h.Experiments.Get(context.Background(), loop.Experiment)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if exp.Allocation["control"] != 0.9 || exp.Allocation["candidate"] != 0.1 {
+		t.Errorf("allocation was %v, want a 90/10 split", exp.Allocation)
+	}
+
+	// 9. Fitness comparison.
+	if loop.Evaluation.Verdict != fitness.VerdictSucceeded {
+		t.Fatalf("verdict %s: %v", loop.Evaluation.Verdict, loop.Evaluation.Reasons)
+	}
+	primary := loop.Evaluation.PrimaryResults()
+	if len(primary) != 1 {
+		t.Fatalf("expected one primary metric, got %d", len(primary))
+	}
+	// The candidate should show the reduction the hypothesis predicted.
+	if primary[0].Current >= primary[0].Baseline {
+		t.Errorf("requests per task did not fall: %v -> %v",
+			primary[0].Baseline, primary[0].Current)
+	}
+	t.Logf("requests per completed task: %.2f -> %.2f (target %.2f)",
+		primary[0].Baseline, primary[0].Current, *primary[0].Target)
+
+	// 10. Promotion.
+	if loop.Decision.Outcome != promotion.Promote {
+		t.Errorf("decision was %s, want PROMOTE", loop.Decision.Outcome)
+	}
+	if loop.Decision.Override {
+		t.Error("the promotion was an override; the evidence should have carried it")
+	}
+
+	// 11. A complete audit trail.
+	//
+	// Every stage of the loop must have left a reconstructable record. This is
+	// the assertion that would fail first if any part of the framework started
+	// deciding things without saying so.
+	events := h.Events(string(loop.Candidate))
+	required := map[string]bool{
+		"SIGN_PASSED":               false,
+		"POLICY_CHECK_PASSED":       false,
+		"INTENT_BOUND":              false,
+		"REVISION_PUBLISHED":        false,
+		"PROMOTION_DECIDED_PROMOTE": false,
+	}
+	for _, ev := range events {
+		if _, tracked := required[ev.EventType]; tracked {
+			required[ev.EventType] = true
+		}
+	}
+	for name, seen := range required {
+		if !seen {
+			t.Errorf("the audit trail is missing %s", name)
+		}
+	}
+
+	// The pressure, hypothesis and experiment each left their own trail.
+	for _, entity := range []string{
+		string(loop.Pressure), string(loop.Hypothesis), string(loop.Experiment),
+	} {
+		if len(h.Events(entity)) == 0 {
+			t.Errorf("%s left no audit events", entity)
+		}
+	}
+
+	t.Logf("slice complete: %s -> %s -> %s -> %s (%s)",
+		loop.Pressure, loop.Hypothesis, loop.Experiment, loop.Candidate, loop.Decision.Outcome)
+}
+
+// TestSliceIsReproducible runs the loop twice over fresh state and requires the
+// same conclusion both times.
+//
+// A loop whose verdict depended on run order would be measuring the harness
+// rather than the interface.
+func TestSliceIsReproducible(t *testing.T) {
+	var verdicts []fitness.Verdict
+	var ratios []float64
+
+	for i := 0; i < 2; i++ {
+		h := New(t)
+		loop := RunFullLoop(t, h)
+		verdicts = append(verdicts, loop.Evaluation.Verdict)
+		ratios = append(ratios, loop.Evaluation.PrimaryResults()[0].Current)
+	}
+
+	if verdicts[0] != verdicts[1] {
+		t.Errorf("verdict varied between runs: %s then %s", verdicts[0], verdicts[1])
+	}
+	if ratios[0] != ratios[1] {
+		t.Errorf("measured ratio varied between runs: %v then %v", ratios[0], ratios[1])
+	}
+}
+
+// TestSliceRefusesPromotionWithoutEvidence confirms the loop cannot be
+// short-circuited: the same candidate, promoted without its experiment, is
+// refused.
+func TestSliceRefusesPromotionWithoutEvidence(t *testing.T) {
+	h := New(t)
+
+	descriptor, err := h.Registry.Revision("R-2")
+	if err != nil {
+		t.Fatal(err)
+	}
+	governing, err := h.Intents.GoverningIntent(context.Background(), "R-2")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	limits := policy.DefaultLimits()
+	limits.AllowedAdaptationClasses = append(limits.AllowedAdaptationClasses,
+		contract.AdaptationClassContract)
+	limits.RequiredMode = intent.ModeExperimental
+
+	_, err = promotion.NewController(h.Store, policy.NewGate(limits)).Decide(context.Background(), promotion.Request{
+		Revision: "R-2",
+		Outcome:  promotion.Promote,
+		Reason:   "it looks better",
+		Actor:    Operator,
+		GateInput: &policy.Input{
+			Descriptor:            descriptor,
+			GoverningMode:         governing.Mode,
+			AdaptationClasses:     []contract.AdaptationClass{contract.AdaptationClassContract},
+			RequestedTrafficShare: 0.2,
+			Approved:              true,
+			ApprovedBy:            &Operator,
+		},
+	})
+	if err == nil {
+		t.Fatal("a candidate was promoted with no fitness evidence")
+	}
+	if !strings.Contains(err.Error(), "fitness") {
+		t.Errorf("refusal does not cite missing evidence: %v", err)
+	}
+}

docs/integration-guide.md

@@ -0,0 +1,137 @@
+# Putting an existing API behind fluid-core
+
+fluid-core attaches **out of process** (ADR-0002). Your API contributes no code,
+imports no library, and may be written in any stack. Integration is over a wire
+contract, so the fact that fluid-core is written in Go is not something you need
+to care about.
+
+## What you need
+
+1. **A running service.** Anything that speaks HTTP. This becomes an *adapter*.
+2. **A contract.** OpenAPI 3.1 today; the validator interface admits others.
+3. **An interface evolution intent.** The governance document that bounds how
+   the interface may change.
+
+Nothing else. In particular you do not need a Kubernetes cluster, a message
+broker, or Postgres — SQLite is the default evidence store.
+
+## The five minutes version
+
+```bash
+export FLUID_INTERFACE=my-api
+export FLUID_STORE=$PWD/fluid.db
+
+# 1. Record the intent that governs this interface.
+fluid intent put --version IEI-1 --file InterfaceEvolutionIntent.md --activate
+
+# 2. Publish a revision pointing at your existing service.
+fluid revision publish --file r1.yaml --ephemeral-key \
+  --adaptation-classes presentation --approved-by "$USER" --traffic-share 1.0
+
+# 3. Route traffic to it.
+fluid policy put --file routing-policy.yaml
+```
+
+A revision descriptor is small:
+
+```yaml
+revision:
+  schema_version: "0.1"
+  id: "R-1"
+  interface: "my-api"
+  state: "stable"
+  contract:
+    type: "openapi"
+    digest: "sha256:<digest of your OpenAPI document>"
+  runtime:
+    upstream: "http://my-existing-service:8080"   # your service, unchanged
+    timeout_ms: 5000
+  intent:
+    version: "IEI-1"
+  policy:
+    compatibility: "additive"
+    security_check: "passed"
+```
+
+`runtime.upstream` is the whole integration. Everything else is metadata about
+what that upstream is allowed to be.
+
+## What you get immediately
+
+- **Revision identity.** Every response names the revision that served it.
+- **Telemetry.** Requests, errors, call sequences and adoption, redacted before
+  storage.
+- **Contract enforcement.** Undeclared paths, methods and fields are refused
+  rather than proxied.
+- **An audit trail.** `fluid audit trace R-1` reconstructs how a revision came
+  to exist and what happened to it.
+
+That is FLUID-0 (Instrumented) conformance, and it needs no AI and no change to
+your service.
+
+## What you should decide deliberately
+
+**The pseudonymization salt.** Consumer identities are pseudonymized with HMAC.
+The salt must be stable for the life of the interface — rotating it makes the
+same consumer look like a new one and breaks every longitudinal comparison.
+Store it where you store secrets, not in the repository.
+
+**The authority mode.** Your intent document declares one, `FLUID-0` through
+`FLUID-6`. This is a statement about authority, not maturity: a high-assurance
+interface may deliberately stay at FLUID-2 forever. The unfilled template is
+refused rather than defaulted, precisely so nobody inherits a permissive mode by
+accident.
+
+**Your complexity budget.** `policy.DefaultLimits()` permits only presentation
+and implementation adaptations, refuses breaking changes, and caps exposure at
+25%. If your interface needs more, say so explicitly in the intent rather than
+widening the default.
+
+## Adding a second revision
+
+This is where FLUID earns its keep. Publish a second revision pointing at a
+second adapter — a different build, a different service, a different language —
+and let the experiment controller split traffic between them:
+
+```bash
+fluid revision publish --file r2.yaml --ephemeral-key ...
+fluid experiment design --file experiment.yaml
+fluid experiment start E-1 --generation 2 --default-revision R-1 --policy-out rp.json
+fluid policy put --file rp.json
+```
+
+The controller does not touch traffic. It emits a routing policy for you to
+install, which is what makes an experiment interruptible: stopping one replaces
+a document rather than unwinding anything.
+
+## Signing
+
+`--ephemeral-key` is for development. It generates a throwaway key and warns
+that revisions signed with it will not verify after a restart, which is exactly
+what you want to hear before it happens in production.
+
+In production, generate a key pair, keep the private half in your secret store,
+and configure the gateway's registry with the public half. The router accepts
+only descriptors that verify — an unsigned or tampered descriptor is refused,
+including one that was signed and then edited.
+
+## What fluid-core will not do for you
+
+- **It will not modify your backend.** Where a candidate needs capability the
+  backend does not have, FLUID emits a structured requirement and stops. The
+  backend owner accepts, plans, or declares it out of scope.
+- **It will not decide what "better" means.** There is no universal fitness
+  scalar. You declare primary metrics and guardrails; the evaluator compares
+  against what you declared and refuses to infer criteria from the data.
+- **It will not promote on thin evidence.** A comparison below the sample floor
+  is inconclusive, not successful. You can override that with an acknowledged
+  flag; the override is recorded as one.
+
+## Reference
+
+- `examples/echo-interface/` — the two-revision fixture the conformance suite
+  drives, and the smallest complete example.
+- `conformance/suite/` — every conformance requirement asserted as a test.
+  `TestFirstVerticalSlice` is the whole loop in one function.
+- `spec/` — the normative documents. When this guide and the spec disagree, the
+  spec is right and this guide is a bug.

examples/echo-interface/README.md

@@ -0,0 +1,21 @@
+# echo-interface
+
+The smallest honest reproduction of the `ArchitectureBlueprint.md` §33 worked
+example, used as the conformance fixture.
+
+Two revisions of one interface over the same backend data:
+
+| Revision | Shape | Requests per completed task |
+|---|---|---|
+| **R-1** | `GET /v1/entries` only — consumers list everything and filter locally | ~3 |
+| **R-2** | adds `GET /v1/entries/latest` — the concept consumers actually wanted | 1 |
+
+R-1 is not a strawman. It is the interface a careful designer produces before
+they have seen how it is used: a clean collection resource with no special
+cases. The pressure it generates is the point — consumers repeatedly fetching
+a collection to discard all but one item is the evidence that "latest" is a
+first-class concept the contract failed to name.
+
+The fixture has no external dependencies and runs in CI. It exists so the
+revision–experiment–fitness loop is proven mechanically before a real workload
+depends on it.

examples/echo-interface/adapter.go

@@ -0,0 +1,67 @@
+// Package echo provides the conformance fixture adapters.
+//
+// Two revisions over the same data: R-1 exposes only a collection, R-2 adds the
+// convenience resource. Both are ordinary deterministic HTTP handlers, which is
+// the point — an adapter is a normal service, and fluid-core sits in front of
+// it without asking anything of it.
+package echo
+
+import (
+	"encoding/json"
+	"net/http"
+	"sort"
+	"time"
+)
+
+// Entry is one record the fixture serves.
+type Entry struct {
+	ID        string    `json:"id"`
+	Title     string    `json:"title"`
+	CreatedAt time.Time `json:"created_at"`
+}
+
+// Data returns a deterministic set of entries.
+//
+// Fixed timestamps rather than time.Now: a conformance suite whose fixture
+// changes between runs cannot distinguish a regression from the clock.
+func Data() []Entry {
+	base := time.Date(2026, 9, 1, 12, 0, 0, 0, time.UTC)
+	return []Entry{
+		{ID: "e-1", Title: "the river reached the forge", CreatedAt: base},
+		{ID: "e-2", Title: "nine doors stayed honest", CreatedAt: base.Add(24 * time.Hour)},
+		{ID: "e-3", Title: "the reviewing side", CreatedAt: base.Add(48 * time.Hour)},
+	}
+}
+
+// NewR1 returns the collection-only adapter.
+//
+// A consumer wanting the newest entry must fetch the whole collection, sort it
+// and discard the rest. That is the interface pressure the fixture generates.
+func NewR1() http.Handler {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/v1/entries", func(w http.ResponseWriter, r *http.Request) {
+		writeJSON(w, Data())
+	})
+	return mux
+}
+
+// NewR2 returns the adapter with the convenience resource added.
+func NewR2() http.Handler {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/v1/entries", func(w http.ResponseWriter, r *http.Request) {
+		writeJSON(w, Data())
+	})
+	mux.HandleFunc("/v1/entries/latest", func(w http.ResponseWriter, r *http.Request) {
+		entries := Data()
+		sort.Slice(entries, func(i, j int) bool {
+			return entries[i].CreatedAt.After(entries[j].CreatedAt)
+		})
+		writeJSON(w, entries[0])
+	})
+	return mux
+}
+
+func writeJSON(w http.ResponseWriter, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(v)
+}

examples/echo-interface/r1.openapi.yaml

@@ -0,0 +1,12 @@
+openapi: "3.1.0"
+info:
+  title: echo-interface
+  version: "1"
+paths:
+  /v1/entries:
+    get:
+      operationId: listEntries
+      parameters:
+        - name: limit
+          in: query
+          schema: {type: integer, minimum: 1, maximum: 100}

examples/echo-interface/r2.openapi.yaml

@@ -0,0 +1,15 @@
+openapi: "3.1.0"
+info:
+  title: echo-interface
+  version: "2"
+paths:
+  /v1/entries:
+    get:
+      operationId: listEntries
+      parameters:
+        - name: limit
+          in: query
+          schema: {type: integer, minimum: 1, maximum: 100}
+  /v1/entries/latest:
+    get:
+      operationId: latestEntry

internal/runtime/telemetry.go

@@ -29,6 +29,7 @@ type Emitter struct {
 	dropped  atomic.Int64
 	written  atomic.Int64
 	failed   atomic.Int64
+	inflight atomic.Int64
 	stopOnce sync.Once
 	done     chan struct{}
 	wg       sync.WaitGroup
@@ -76,6 +77,7 @@ func NewEmitter(sink Sink, opts EmitterOptions) *Emitter {
 func (e *Emitter) Emit(ev contract.FluidTelemetry) {
 	select {
 	case e.ch <- ev:
+		e.inflight.Add(1)
 	default:
 		e.dropped.Add(1)
 	}
@@ -89,25 +91,13 @@ func (e *Emitter) run(timeout time.Duration) {
 			if !ok {
 				return
 			}
-			ctx, cancel := context.WithTimeout(context.Background(), timeout)
-			if err := e.sink.Write(ctx, ev); err != nil {
-				e.failed.Add(1)
-			} else {
-				e.written.Add(1)
-			}
-			cancel()
+			e.deliver(ev, timeout)
 		case <-e.done:
 			// Drain what is already buffered, then stop.
 			for {
 				select {
 				case ev := <-e.ch:
-					ctx, cancel := context.WithTimeout(context.Background(), timeout)
-					if err := e.sink.Write(ctx, ev); err != nil {
-						e.failed.Add(1)
-					} else {
-						e.written.Add(1)
-					}
-					cancel()
+					e.deliver(ev, timeout)
 				default:
 					return
 				}
@@ -116,6 +106,39 @@ func (e *Emitter) run(timeout time.Duration) {
 	}
 }
 
+// deliver writes one event and settles its in-flight accounting.
+func (e *Emitter) deliver(ev contract.FluidTelemetry, timeout time.Duration) {
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	if err := e.sink.Write(ctx, ev); err != nil {
+		e.failed.Add(1)
+	} else {
+		e.written.Add(1)
+	}
+	cancel()
+	e.inflight.Add(-1)
+}
+
+// Flush waits for queued telemetry to reach the sink without stopping delivery.
+//
+// It exists for tests and for operational tooling that needs to read back what
+// it just emitted. Close would also flush, but closing an emitter that is still
+// serving traffic silently drops everything emitted afterwards -- which is the
+// kind of bug that makes a later measurement quietly wrong rather than loudly
+// broken.
+//
+// It returns false if the deadline passes with work still outstanding, so a
+// caller can tell a slow sink from an empty one.
+func (e *Emitter) Flush(timeout time.Duration) bool {
+	deadline := time.Now().Add(timeout)
+	for time.Now().Before(deadline) {
+		if e.inflight.Load() == 0 && len(e.ch) == 0 {
+			return true
+		}
+		time.Sleep(time.Millisecond)
+	}
+	return e.inflight.Load() == 0 && len(e.ch) == 0
+}
+
 // Close stops delivery after draining the buffer.
 func (e *Emitter) Close() {
 	e.stopOnce.Do(func() { close(e.done) })

internal/signing/signing.go

@@ -9,12 +9,16 @@ package signing
 
 import (
 	"crypto/ed25519"
+	"crypto/sha256"
 	"encoding/base64"
+	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"sort"
 	"strings"
+
+	"github.com/tegwick/fluid-core/internal/contract"
 )
 
 // Algorithm is the only signature algorithm FLUID defines.
@@ -195,6 +199,12 @@ func (v *Verifier) Verify(document any, sig *Signature) error {
 	return nil
 }
 
+// Digest content-addresses a raw artifact such as a contract document.
+func Digest(raw []byte) contract.Digest {
+	sum := sha256.Sum256(raw)
+	return contract.Digest("sha256:" + hex.EncodeToString(sum[:]))
+}
+
 // GenerateKey produces a new signing key pair. Intended for development and
 // tests; production keys should come from the deployment's key management.
 func GenerateKey(keyID string) (*Signer, ed25519.PublicKey, error) {

internal/validate/jsonschema.go

@@ -0,0 +1,393 @@
+// Package validate implements deterministic contract validation.
+//
+// ArchitectureBlueprint.md section 5.4 requires each revision to have an
+// identifiable contract the gateway can enforce, and FluidAPIStandards.md
+// section 36 makes "a deterministic API contract" the first minimal-conformance
+// requirement. Validation must therefore be a pure function of the request and
+// the contract: no inference, no model, no defaults invented at runtime.
+//
+// The JSON Schema support here is a documented subset rather than a complete
+// implementation. The subset covers what an interface contract actually
+// constrains — types, required members, enums, bounds and nesting — and
+// anything outside it is reported as unsupported rather than silently passed.
+// A validator that quietly ignores a keyword it does not understand is worse
+// than no validator, because it reports success.
+package validate
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"sort"
+	"strings"
+)
+
+// Schema is the supported JSON Schema subset.
+type Schema struct {
+	Type                 any                `json:"type,omitempty" yaml:"type,omitempty"`
+	Properties           map[string]*Schema `json:"properties,omitempty" yaml:"properties,omitempty"`
+	Required             []string           `json:"required,omitempty" yaml:"required,omitempty"`
+	Items                *Schema            `json:"items,omitempty" yaml:"items,omitempty"`
+	Enum                 []any              `json:"enum,omitempty" yaml:"enum,omitempty"`
+	Format               string             `json:"format,omitempty" yaml:"format,omitempty"`
+	AdditionalProperties *bool              `json:"additionalProperties,omitempty" yaml:"additionalProperties,omitempty"`
+
+	Minimum   *float64 `json:"minimum,omitempty" yaml:"minimum,omitempty"`
+	Maximum   *float64 `json:"maximum,omitempty" yaml:"maximum,omitempty"`
+	MinLength *int     `json:"minLength,omitempty" yaml:"minLength,omitempty"`
+	MaxLength *int     `json:"maxLength,omitempty" yaml:"maxLength,omitempty"`
+	MinItems  *int     `json:"minItems,omitempty" yaml:"minItems,omitempty"`
+	MaxItems  *int     `json:"maxItems,omitempty" yaml:"maxItems,omitempty"`
+
+	Ref string `json:"$ref,omitempty" yaml:"$ref,omitempty"`
+
+	// Nullable follows OpenAPI 3.0; 3.1 uses a type union instead. Both are
+	// accepted because contracts in the wild use both.
+	Nullable bool `json:"nullable,omitempty" yaml:"nullable,omitempty"`
+}
+
+// Violation is one contract breach, named precisely enough to fix.
+type Violation struct {
+	// Path locates the offending value, such as "body.entry.title".
+	Path string
+	// Message says what is wrong in terms the consumer can act on.
+	Message string
+}
+
+func (v Violation) String() string {
+	if v.Path == "" {
+		return v.Message
+	}
+	return v.Path + ": " + v.Message
+}
+
+// Result collects violations from one validation.
+type Result struct {
+	Violations []Violation
+}
+
+// OK reports whether validation passed.
+func (r *Result) OK() bool { return len(r.Violations) == 0 }
+
+// Error renders every violation, most specific path first.
+func (r *Result) Error() string {
+	if r.OK() {
+		return ""
+	}
+	sorted := make([]Violation, len(r.Violations))
+	copy(sorted, r.Violations)
+	sort.Slice(sorted, func(i, j int) bool {
+		if sorted[i].Path != sorted[j].Path {
+			return sorted[i].Path < sorted[j].Path
+		}
+		return sorted[i].Message < sorted[j].Message
+	})
+
+	parts := make([]string, len(sorted))
+	for i, v := range sorted {
+		parts[i] = v.String()
+	}
+	return strings.Join(parts, "; ")
+}
+
+// FirstPath returns the path of the first violation, for error reporting.
+func (r *Result) FirstPath() string {
+	if r.OK() {
+		return ""
+	}
+	best := r.Violations[0].Path
+	for _, v := range r.Violations[1:] {
+		if v.Path < best {
+			best = v.Path
+		}
+	}
+	return best
+}
+
+func (r *Result) add(path, format string, args ...any) {
+	r.Violations = append(r.Violations, Violation{Path: path, Message: fmt.Sprintf(format, args...)})
+}
+
+// ErrUnsupported reports a schema keyword outside the supported subset.
+var ErrUnsupported = errors.New("unsupported schema construct")
+
+// Resolver resolves $ref pointers within a document.
+type Resolver interface {
+	Resolve(ref string) (*Schema, error)
+}
+
+// Validate checks a decoded JSON value against a schema.
+func Validate(value any, schema *Schema, resolver Resolver) *Result {
+	r := &Result{}
+	validateValue(value, schema, "", r, resolver, 0)
+	return r
+}
+
+// maxDepth bounds recursion so a cyclic $ref cannot hang the request path.
+const maxDepth = 64
+
+func validateValue(value any, schema *Schema, path string, r *Result, resolver Resolver, depth int) {
+	if schema == nil {
+		return
+	}
+	if depth > maxDepth {
+		r.add(path, "schema nesting exceeds %d levels; refusing to recurse further", maxDepth)
+		return
+	}
+
+	if schema.Ref != "" {
+		if resolver == nil {
+			r.add(path, "schema uses $ref %q but no resolver is configured", schema.Ref)
+			return
+		}
+		resolved, err := resolver.Resolve(schema.Ref)
+		if err != nil {
+			r.add(path, "cannot resolve $ref %q: %v", schema.Ref, err)
+			return
+		}
+		validateValue(value, resolved, path, r, resolver, depth+1)
+		return
+	}
+
+	if value == nil {
+		if schema.Nullable || typeAllows(schema, "null") {
+			return
+		}
+		if schema.Type != nil {
+			r.add(path, "must not be null")
+		}
+		return
+	}
+
+	if schema.Type != nil && !matchesType(value, schema) {
+		r.add(path, "expected %s, got %s", describeType(schema.Type), goTypeName(value))
+		return
+	}
+
+	if len(schema.Enum) > 0 && !inEnum(value, schema.Enum) {
+		r.add(path, "value %v is not one of %v", value, schema.Enum)
+	}
+
+	switch v := value.(type) {
+	case map[string]any:
+		validateObject(v, schema, path, r, resolver, depth)
+	case []any:
+		validateArray(v, schema, path, r, resolver, depth)
+	case string:
+		validateString(v, schema, path, r)
+	case float64:
+		validateNumber(v, schema, path, r)
+	}
+}
+
+func validateObject(obj map[string]any, schema *Schema, path string, r *Result, resolver Resolver, depth int) {
+	for _, req := range schema.Required {
+		if _, ok := obj[req]; !ok {
+			r.add(join(path, req), "is required")
+		}
+	}
+
+	if schema.AdditionalProperties != nil && !*schema.AdditionalProperties && schema.Properties != nil {
+		keys := make([]string, 0, len(obj))
+		for k := range obj {
+			keys = append(keys, k)
+		}
+		sort.Strings(keys)
+		for _, k := range keys {
+			if _, declared := schema.Properties[k]; !declared {
+				// An unknown field is a discoverability signal as much as an
+				// error: it is usually a consumer guessing at a capability.
+				r.add(join(path, k), "is not a field of this contract")
+			}
+		}
+	}
+
+	if schema.Properties == nil {
+		return
+	}
+	names := make([]string, 0, len(schema.Properties))
+	for name := range schema.Properties {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+
+	for _, name := range names {
+		if v, ok := obj[name]; ok {
+			validateValue(v, schema.Properties[name], join(path, name), r, resolver, depth+1)
+		}
+	}
+}
+
+func validateArray(arr []any, schema *Schema, path string, r *Result, resolver Resolver, depth int) {
+	if schema.MinItems != nil && len(arr) < *schema.MinItems {
+		r.add(path, "needs at least %d items, has %d", *schema.MinItems, len(arr))
+	}
+	if schema.MaxItems != nil && len(arr) > *schema.MaxItems {
+		r.add(path, "allows at most %d items, has %d", *schema.MaxItems, len(arr))
+	}
+	if schema.Items == nil {
+		return
+	}
+	for i, item := range arr {
+		validateValue(item, schema.Items, fmt.Sprintf("%s[%d]", path, i), r, resolver, depth+1)
+	}
+}
+
+func validateString(s string, schema *Schema, path string, r *Result) {
+	// Length is counted in runes, not bytes. A 4096-character limit that
+	// rejected a 3000-character entry because of accents would be wrong in
+	// exactly the case this framework was built to publish.
+	length := len([]rune(s))
+	if schema.MinLength != nil && length < *schema.MinLength {
+		r.add(path, "needs at least %d characters, has %d", *schema.MinLength, length)
+	}
+	if schema.MaxLength != nil && length > *schema.MaxLength {
+		r.add(path, "allows at most %d characters, has %d", *schema.MaxLength, length)
+	}
+}
+
+func validateNumber(n float64, schema *Schema, path string, r *Result) {
+	if schema.Minimum != nil && n < *schema.Minimum {
+		r.add(path, "must be at least %v", *schema.Minimum)
+	}
+	if schema.Maximum != nil && n > *schema.Maximum {
+		r.add(path, "must be at most %v", *schema.Maximum)
+	}
+}
+
+// typeAllows reports whether a schema's type declaration includes want.
+func typeAllows(schema *Schema, want string) bool {
+	switch t := schema.Type.(type) {
+	case string:
+		return t == want
+	case []any:
+		for _, v := range t {
+			if s, ok := v.(string); ok && s == want {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func matchesType(value any, schema *Schema) bool {
+	names := typeNames(schema.Type)
+	if len(names) == 0 {
+		return true
+	}
+	for _, name := range names {
+		if matchesSingleType(value, name) {
+			return true
+		}
+	}
+	return false
+}
+
+func matchesSingleType(value any, name string) bool {
+	switch name {
+	case "object":
+		_, ok := value.(map[string]any)
+		return ok
+	case "array":
+		_, ok := value.([]any)
+		return ok
+	case "string":
+		_, ok := value.(string)
+		return ok
+	case "boolean":
+		_, ok := value.(bool)
+		return ok
+	case "number":
+		_, ok := value.(float64)
+		return ok
+	case "integer":
+		// JSON has one number type; an integer is a number with no fraction.
+		f, ok := value.(float64)
+		return ok && f == math.Trunc(f)
+	case "null":
+		return value == nil
+	}
+	return true
+}
+
+func typeNames(t any) []string {
+	switch v := t.(type) {
+	case string:
+		return []string{v}
+	case []any:
+		out := make([]string, 0, len(v))
+		for _, item := range v {
+			if s, ok := item.(string); ok {
+				out = append(out, s)
+			}
+		}
+		return out
+	}
+	return nil
+}
+
+func describeType(t any) string {
+	names := typeNames(t)
+	if len(names) == 0 {
+		return "any"
+	}
+	return strings.Join(names, " or ")
+}
+
+func goTypeName(v any) string {
+	switch t := v.(type) {
+	case map[string]any:
+		return "object"
+	case []any:
+		return "array"
+	case string:
+		return "string"
+	case bool:
+		return "boolean"
+	case float64:
+		if t == math.Trunc(t) {
+			return "integer"
+		}
+		return "number"
+	case nil:
+		return "null"
+	}
+	return fmt.Sprintf("%T", v)
+}
+
+func inEnum(value any, enum []any) bool {
+	for _, candidate := range enum {
+		if equalJSON(value, candidate) {
+			return true
+		}
+	}
+	return false
+}
+
+func equalJSON(a, b any) bool {
+	switch av := a.(type) {
+	case string:
+		bv, ok := b.(string)
+		return ok && av == bv
+	case float64:
+		switch bv := b.(type) {
+		case float64:
+			return av == bv
+		case int:
+			return av == float64(bv)
+		}
+	case bool:
+		bv, ok := b.(bool)
+		return ok && av == bv
+	case nil:
+		return b == nil
+	}
+	return fmt.Sprint(a) == fmt.Sprint(b)
+}
+
+func join(path, name string) string {
+	if path == "" {
+		return name
+	}
+	return path + "." + name
+}

internal/validate/openapi.go

@@ -0,0 +1,405 @@
+package validate
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"sort"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+
+	"github.com/tegwick/fluid-core/internal/contract"
+	"github.com/tegwick/fluid-core/internal/runtime"
+)
+
+// Document is the supported subset of an OpenAPI description.
+type Document struct {
+	OpenAPI    string               `json:"openapi" yaml:"openapi"`
+	Paths      map[string]*PathItem `json:"paths" yaml:"paths"`
+	Components *Components          `json:"components,omitempty" yaml:"components,omitempty"`
+}
+
+// Components holds reusable schemas.
+type Components struct {
+	Schemas map[string]*Schema `json:"schemas,omitempty" yaml:"schemas,omitempty"`
+}
+
+// PathItem holds the operations available at one path.
+type PathItem struct {
+	Get    *Operation `json:"get,omitempty" yaml:"get,omitempty"`
+	Put    *Operation `json:"put,omitempty" yaml:"put,omitempty"`
+	Post   *Operation `json:"post,omitempty" yaml:"post,omitempty"`
+	Delete *Operation `json:"delete,omitempty" yaml:"delete,omitempty"`
+	Patch  *Operation `json:"patch,omitempty" yaml:"patch,omitempty"`
+	Head   *Operation `json:"head,omitempty" yaml:"head,omitempty"`
+}
+
+// operations returns the declared operations by method.
+func (p *PathItem) operations() map[string]*Operation {
+	out := map[string]*Operation{}
+	for method, op := range map[string]*Operation{
+		http.MethodGet: p.Get, http.MethodPut: p.Put, http.MethodPost: p.Post,
+		http.MethodDelete: p.Delete, http.MethodPatch: p.Patch, http.MethodHead: p.Head,
+	} {
+		if op != nil {
+			out[method] = op
+		}
+	}
+	return out
+}
+
+// Operation is one method on one path.
+type Operation struct {
+	OperationID string       `json:"operationId,omitempty" yaml:"operationId,omitempty"`
+	Parameters  []*Parameter `json:"parameters,omitempty" yaml:"parameters,omitempty"`
+	RequestBody *RequestBody `json:"requestBody,omitempty" yaml:"requestBody,omitempty"`
+}
+
+// Parameter is a path, query or header parameter.
+type Parameter struct {
+	Name     string  `json:"name" yaml:"name"`
+	In       string  `json:"in" yaml:"in"`
+	Required bool    `json:"required,omitempty" yaml:"required,omitempty"`
+	Schema   *Schema `json:"schema,omitempty" yaml:"schema,omitempty"`
+}
+
+// RequestBody describes an operation's body.
+type RequestBody struct {
+	Required bool                  `json:"required,omitempty" yaml:"required,omitempty"`
+	Content  map[string]*MediaType `json:"content,omitempty" yaml:"content,omitempty"`
+}
+
+// MediaType binds a content type to a schema.
+type MediaType struct {
+	Schema *Schema `json:"schema,omitempty" yaml:"schema,omitempty"`
+}
+
+// Contract is a parsed, validated OpenAPI description ready to enforce.
+type Contract struct {
+	doc    *Document
+	routes []route
+}
+
+// route is one compiled path template.
+type route struct {
+	template string
+	segments []segment
+	item     *PathItem
+}
+
+type segment struct {
+	literal  string
+	variable string
+}
+
+// ParseOpenAPI compiles an OpenAPI document.
+//
+// Parsing happens once, at revision publication, not per request. Compiling a
+// contract on the hot path would put an unbounded amount of work between a
+// consumer and their response for no benefit, since the contract cannot change
+// without a new revision.
+func ParseOpenAPI(raw []byte) (*Contract, error) {
+	var doc Document
+	if err := yaml.Unmarshal(raw, &doc); err != nil {
+		return nil, fmt.Errorf("parse contract: %w", err)
+	}
+	if len(doc.Paths) == 0 {
+		return nil, fmt.Errorf("contract declares no paths")
+	}
+
+	templates := make([]string, 0, len(doc.Paths))
+	for t := range doc.Paths {
+		templates = append(templates, t)
+	}
+	// Sorting makes route order deterministic. Two templates can match the same
+	// request, and which one wins must not depend on map iteration.
+	sort.Strings(templates)
+
+	c := &Contract{doc: &doc}
+	for _, t := range templates {
+		c.routes = append(c.routes, route{
+			template: t,
+			segments: compile(t),
+			item:     doc.Paths[t],
+		})
+	}
+
+	// Literal routes are matched before templated ones, so /entries/latest
+	// wins over /entries/{id} regardless of alphabetical order.
+	sort.SliceStable(c.routes, func(i, j int) bool {
+		return variableCount(c.routes[i].segments) < variableCount(c.routes[j].segments)
+	})
+	return c, nil
+}
+
+func compile(template string) []segment {
+	parts := strings.Split(strings.Trim(template, "/"), "/")
+	out := make([]segment, 0, len(parts))
+	for _, p := range parts {
+		if strings.HasPrefix(p, "{") && strings.HasSuffix(p, "}") {
+			out = append(out, segment{variable: strings.Trim(p, "{}")})
+			continue
+		}
+		out = append(out, segment{literal: p})
+	}
+	return out
+}
+
+func variableCount(segs []segment) int {
+	n := 0
+	for _, s := range segs {
+		if s.variable != "" {
+			n++
+		}
+	}
+	return n
+}
+
+// match finds the route serving a path, with its extracted variables.
+func (c *Contract) match(path string) (route, map[string]string, bool) {
+	parts := strings.Split(strings.Trim(path, "/"), "/")
+
+	for _, r := range c.routes {
+		if len(r.segments) != len(parts) {
+			continue
+		}
+		vars := map[string]string{}
+		ok := true
+		for i, seg := range r.segments {
+			if seg.variable != "" {
+				if parts[i] == "" {
+					ok = false
+					break
+				}
+				vars[seg.variable] = parts[i]
+				continue
+			}
+			if seg.literal != parts[i] {
+				ok = false
+				break
+			}
+		}
+		if ok {
+			return r, vars, true
+		}
+	}
+	return route{}, nil, false
+}
+
+// Resolve implements Resolver for local component references.
+func (c *Contract) Resolve(ref string) (*Schema, error) {
+	const prefix = "#/components/schemas/"
+	if !strings.HasPrefix(ref, prefix) {
+		// Remote references would make validation depend on a network fetch,
+		// which the request path must never do.
+		return nil, fmt.Errorf("%w: only local %s references are supported", ErrUnsupported, prefix)
+	}
+	if c.doc.Components == nil {
+		return nil, fmt.Errorf("contract declares no components")
+	}
+	s, ok := c.doc.Components.Schemas[strings.TrimPrefix(ref, prefix)]
+	if !ok {
+		return nil, fmt.Errorf("no such component schema")
+	}
+	return s, nil
+}
+
+// Operations lists the operations the contract declares, for complexity
+// measurement and for reporting surface area.
+func (c *Contract) Operations() []string {
+	var out []string
+	for _, r := range c.routes {
+		for method := range r.item.operations() {
+			out = append(out, method+" "+r.template)
+		}
+	}
+	sort.Strings(out)
+	return out
+}
+
+// OpenAPIValidator enforces a compiled contract at the gateway.
+//
+// It implements runtime.ContractValidator. Contracts are compiled per revision
+// and cached by contract digest: two revisions sharing a contract share the
+// compiled form, and a changed contract is a different digest and so a
+// different entry.
+type OpenAPIValidator struct {
+	contracts map[contract.Digest]*Contract
+}
+
+// NewOpenAPIValidator returns a validator holding no contracts.
+func NewOpenAPIValidator() *OpenAPIValidator {
+	return &OpenAPIValidator{contracts: map[contract.Digest]*Contract{}}
+}
+
+// Register compiles and stores the contract for a digest.
+func (v *OpenAPIValidator) Register(digest contract.Digest, raw []byte) error {
+	c, err := ParseOpenAPI(raw)
+	if err != nil {
+		return err
+	}
+	v.contracts[digest] = c
+	return nil
+}
+
+// Contract returns a registered contract.
+func (v *OpenAPIValidator) Contract(digest contract.Digest) (*Contract, bool) {
+	c, ok := v.contracts[digest]
+	return c, ok
+}
+
+// Validate checks a request against its revision's contract.
+//
+// An unregistered contract is a refusal, not a pass. A gateway that served
+// traffic for a revision whose contract it could not find would be serving
+// undeclared semantics, which is the thing minimal conformance forbids.
+func (v *OpenAPIValidator) Validate(rev contract.Revision, r *http.Request, body []byte) error {
+	c, ok := v.contracts[rev.Contract.Digest]
+	if !ok {
+		return &runtime.ValidationError{
+			Message: fmt.Sprintf("no contract registered for revision %s", rev.ID),
+		}
+	}
+
+	matched, pathVars, found := c.match(r.URL.Path)
+	if !found {
+		return &runtime.ValidationError{
+			Message: fmt.Sprintf("%s is not a path in this contract", r.URL.Path),
+		}
+	}
+
+	op, ok := matched.item.operations()[r.Method]
+	if !ok {
+		allowed := make([]string, 0)
+		for method := range matched.item.operations() {
+			allowed = append(allowed, method)
+		}
+		sort.Strings(allowed)
+		return &runtime.ValidationError{
+			Message: fmt.Sprintf("%s is not allowed on %s; the contract declares %s",
+				r.Method, matched.template, strings.Join(allowed, ", ")),
+		}
+	}
+
+	result := &Result{}
+	validateParameters(op, r, pathVars, result, c)
+	validateBody(op, r, body, result, c)
+
+	if !result.OK() {
+		return &runtime.ValidationError{
+			Field:   result.FirstPath(),
+			Message: result.Error(),
+		}
+	}
+	return nil
+}
+
+func validateParameters(op *Operation, r *http.Request, pathVars map[string]string, result *Result, resolver Resolver) {
+	query := r.URL.Query()
+
+	for _, p := range op.Parameters {
+		if p == nil {
+			continue
+		}
+		var (
+			raw     string
+			present bool
+		)
+		switch p.In {
+		case "path":
+			raw, present = pathVars[p.Name]
+		case "query":
+			present = query.Has(p.Name)
+			raw = query.Get(p.Name)
+		case "header":
+			raw = r.Header.Get(p.Name)
+			present = raw != ""
+		default:
+			// Cookie parameters and anything else are reported rather than
+			// ignored: silently skipping a constraint is how a validator
+			// reports success it did not earn.
+			result.add(p.In+"."+p.Name, "%v: parameter location %q", ErrUnsupported, p.In)
+			continue
+		}
+
+		if !present {
+			if p.Required {
+				result.add(p.In+"."+p.Name, "is required")
+			}
+			continue
+		}
+		if p.Schema != nil {
+			validateValue(coerce(raw, p.Schema), p.Schema, p.In+"."+p.Name, result, resolver, 0)
+		}
+	}
+}
+
+// coerce turns a string parameter into the type its schema declares.
+//
+// Query and path parameters arrive as text; comparing them against a numeric
+// schema without conversion would fail every well-formed request.
+func coerce(raw string, schema *Schema) any {
+	names := typeNames(schema.Type)
+	if len(names) == 0 {
+		return raw
+	}
+	switch names[0] {
+	case "integer", "number":
+		var f float64
+		if _, err := fmt.Sscanf(raw, "%g", &f); err == nil {
+			return f
+		}
+		// Left as a string so the type mismatch is reported honestly rather
+		// than becoming a confusing zero.
+		return raw
+	case "boolean":
+		switch raw {
+		case "true":
+			return true
+		case "false":
+			return false
+		}
+		return raw
+	}
+	return raw
+}
+
+func validateBody(op *Operation, r *http.Request, body []byte, result *Result, resolver Resolver) {
+	if op.RequestBody == nil {
+		return
+	}
+	if len(body) == 0 {
+		if op.RequestBody.Required {
+			result.add("body", "is required")
+		}
+		return
+	}
+
+	mediaType := "application/json"
+	if ct := r.Header.Get("Content-Type"); ct != "" {
+		mediaType = strings.TrimSpace(strings.Split(ct, ";")[0])
+	}
+
+	media, ok := op.RequestBody.Content[mediaType]
+	if !ok {
+		declared := make([]string, 0, len(op.RequestBody.Content))
+		for m := range op.RequestBody.Content {
+			declared = append(declared, m)
+		}
+		sort.Strings(declared)
+		result.add("body", "content type %q is not declared; the contract accepts %s",
+			mediaType, strings.Join(declared, ", "))
+		return
+	}
+	if media == nil || media.Schema == nil {
+		return
+	}
+
+	var decoded any
+	if err := json.Unmarshal(body, &decoded); err != nil {
+		result.add("body", "is not valid JSON: %v", err)
+		return
+	}
+	validateValue(decoded, media.Schema, "body", result, resolver, 0)
+}

internal/validate/openapi_test.go

@@ -0,0 +1,288 @@
+package validate
+
+import (
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/tegwick/fluid-core/internal/contract"
+	"github.com/tegwick/fluid-core/internal/runtime"
+)
+
+const hallContract = `
+openapi: "3.1.0"
+paths:
+  /v1/hall-entries:
+    post:
+      operationId: publishEntry
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              type: object
+              required: [id, title, body]
+              additionalProperties: false
+              properties:
+                id: {type: string, minLength: 1}
+                title: {type: string, maxLength: 120}
+                body: {type: string, maxLength: 4096}
+                format: {type: string, enum: [teaser, full]}
+    get:
+      operationId: listEntries
+      parameters:
+        - name: limit
+          in: query
+          schema: {type: integer, minimum: 1, maximum: 100}
+  /v1/hall-entries/latest:
+    get:
+      operationId: latestEntry
+  /v1/hall-entries/{id}:
+    get:
+      operationId: getEntry
+      parameters:
+        - name: id
+          in: path
+          required: true
+          schema: {type: string, minLength: 1}
+`
+
+func testRevision() contract.Revision {
+	return contract.Revision{
+		ID:       "R-1",
+		Contract: contract.RevisionContract{Digest: contract.Digest("sha256:" + strings.Repeat("1", 64))},
+	}
+}
+
+func newValidator(t *testing.T) *OpenAPIValidator {
+	t.Helper()
+	v := NewOpenAPIValidator()
+	if err := v.Register(testRevision().Contract.Digest, []byte(hallContract)); err != nil {
+		t.Fatal(err)
+	}
+	return v
+}
+
+func request(method, target, body string) *http.Request {
+	var r *http.Request
+	if body == "" {
+		r = httptest.NewRequest(method, target, nil)
+	} else {
+		r = httptest.NewRequest(method, target, strings.NewReader(body))
+		r.Header.Set("Content-Type", "application/json")
+	}
+	return r
+}
+
+func TestValidRequestPasses(t *testing.T) {
+	v := newValidator(t)
+	body := `{"id":"e-1","title":"the river reached the forge","body":"...","format":"teaser"}`
+	if err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body)); err != nil {
+		t.Fatalf("a conforming request was rejected: %v", err)
+	}
+}
+
+func TestRequiredFieldsEnforced(t *testing.T) {
+	v := newValidator(t)
+	body := `{"id":"e-1"}`
+	err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body))
+	if err == nil {
+		t.Fatal("a request missing required fields was accepted")
+	}
+	for _, want := range []string{"title", "body"} {
+		if !strings.Contains(err.Error(), want) {
+			t.Errorf("error does not name missing %q: %v", want, err)
+		}
+	}
+}
+
+// TestLengthLimitIsCountedInRunes is the case this framework exists to publish:
+// a hall entry with accented characters must not be rejected for a byte count
+// it never exceeded.
+func TestLengthLimitIsCountedInRunes(t *testing.T) {
+	v := newValidator(t)
+
+	// 3000 multi-byte runes: well under the 4096 rune limit, well over it in bytes.
+	body := `{"id":"e-1","title":"t","body":"` + strings.Repeat("é", 3000) + `"}`
+	if err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body)); err != nil {
+		t.Fatalf("a 3000-character entry was rejected against a 4096-character limit: %v", err)
+	}
+
+	over := `{"id":"e-1","title":"t","body":"` + strings.Repeat("a", 4097) + `"}`
+	if err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", over), []byte(over)); err == nil {
+		t.Error("a 4097-character entry passed a 4096-character limit")
+	}
+}
+
+func TestUnknownFieldRejectedWhenClosed(t *testing.T) {
+	v := newValidator(t)
+	body := `{"id":"e-1","title":"t","body":"b","urgency":"high"}`
+	err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body))
+	if err == nil {
+		t.Fatal("an undeclared field was accepted")
+	}
+	if !strings.Contains(err.Error(), "urgency") {
+		t.Errorf("error does not name the unknown field: %v", err)
+	}
+}
+
+func TestEnumEnforced(t *testing.T) {
+	v := newValidator(t)
+	body := `{"id":"e-1","title":"t","body":"b","format":"interpretive-dance"}`
+	if err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body)); err == nil {
+		t.Error("a value outside the enum was accepted")
+	}
+}
+
+// TestLiteralRoutesBeatTemplates: /latest must not be swallowed by /{id}.
+func TestLiteralRoutesBeatTemplates(t *testing.T) {
+	c, err := ParseOpenAPI([]byte(hallContract))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	matched, _, ok := c.match("/v1/hall-entries/latest")
+	if !ok {
+		t.Fatal("no route matched /latest")
+	}
+	if matched.template != "/v1/hall-entries/latest" {
+		t.Errorf("matched %q; the literal route must win over the template", matched.template)
+	}
+
+	matched, vars, ok := c.match("/v1/hall-entries/e-7")
+	if !ok {
+		t.Fatal("no route matched an id")
+	}
+	if matched.template != "/v1/hall-entries/{id}" || vars["id"] != "e-7" {
+		t.Errorf("template match wrong: %q vars %v", matched.template, vars)
+	}
+}
+
+func TestUnknownPathAndMethodRejected(t *testing.T) {
+	v := newValidator(t)
+
+	err := v.Validate(testRevision(), request(http.MethodGet, "/v1/nope", ""), nil)
+	if err == nil {
+		t.Error("an undeclared path was accepted")
+	}
+
+	err = v.Validate(testRevision(), request(http.MethodDelete, "/v1/hall-entries", ""), nil)
+	if err == nil {
+		t.Fatal("an undeclared method was accepted")
+	}
+	// The error should say what is allowed; a bare rejection teaches nothing.
+	if !strings.Contains(err.Error(), "GET") || !strings.Contains(err.Error(), "POST") {
+		t.Errorf("error does not name the allowed methods: %v", err)
+	}
+}
+
+func TestQueryParametersAreCoercedAndBounded(t *testing.T) {
+	v := newValidator(t)
+
+	if err := v.Validate(testRevision(), request(http.MethodGet, "/v1/hall-entries?limit=10", ""), nil); err != nil {
+		t.Errorf("a valid numeric query parameter was rejected: %v", err)
+	}
+	if err := v.Validate(testRevision(), request(http.MethodGet, "/v1/hall-entries?limit=500", ""), nil); err == nil {
+		t.Error("a query parameter over its maximum was accepted")
+	}
+	if err := v.Validate(testRevision(), request(http.MethodGet, "/v1/hall-entries?limit=lots", ""), nil); err == nil {
+		t.Error("a non-numeric value for an integer parameter was accepted")
+	}
+	// An absent optional parameter is fine.
+	if err := v.Validate(testRevision(), request(http.MethodGet, "/v1/hall-entries", ""), nil); err != nil {
+		t.Errorf("an absent optional parameter was rejected: %v", err)
+	}
+}
+
+// TestUnregisteredContractIsRefused: serving a revision whose contract cannot
+// be found would mean serving undeclared semantics.
+func TestUnregisteredContractIsRefused(t *testing.T) {
+	v := NewOpenAPIValidator()
+	err := v.Validate(testRevision(), request(http.MethodGet, "/v1/hall-entries", ""), nil)
+	if err == nil {
+		t.Fatal("a revision with no registered contract was served")
+	}
+	var ve *runtime.ValidationError
+	if !errors.As(err, &ve) {
+		t.Errorf("got %T, want *runtime.ValidationError", err)
+	}
+}
+
+func TestMalformedBodyReportedClearly(t *testing.T) {
+	v := newValidator(t)
+	body := `{"id": "e-1",`
+	err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body))
+	if err == nil {
+		t.Fatal("malformed JSON was accepted")
+	}
+	if !strings.Contains(err.Error(), "valid JSON") {
+		t.Errorf("error is not clear about the cause: %v", err)
+	}
+}
+
+func TestRemoteRefsAreRefused(t *testing.T) {
+	// Resolving a remote reference would make validation depend on a network
+	// fetch from the request path.
+	c, err := ParseOpenAPI([]byte(hallContract))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := c.Resolve("https://example.com/schema.json"); !errors.Is(err, ErrUnsupported) {
+		t.Errorf("a remote $ref was accepted: %v", err)
+	}
+}
+
+func TestLocalRefsResolve(t *testing.T) {
+	doc := `
+openapi: "3.1.0"
+components:
+  schemas:
+    Entry:
+      type: object
+      required: [id]
+      properties:
+        id: {type: string}
+paths:
+  /v1/entries:
+    post:
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema: {$ref: "#/components/schemas/Entry"}
+`
+	v := NewOpenAPIValidator()
+	digest := contract.Digest("sha256:" + strings.Repeat("2", 64))
+	if err := v.Register(digest, []byte(doc)); err != nil {
+		t.Fatal(err)
+	}
+
+	rev := testRevision()
+	rev.Contract.Digest = digest
+
+	if err := v.Validate(rev, request(http.MethodPost, "/v1/entries", `{"id":"e-1"}`), []byte(`{"id":"e-1"}`)); err != nil {
+		t.Errorf("a valid referenced body was rejected: %v", err)
+	}
+	if err := v.Validate(rev, request(http.MethodPost, "/v1/entries", `{}`), []byte(`{}`)); err == nil {
+		t.Error("a body missing a required referenced field was accepted")
+	}
+}
+
+func TestOperationsListedForComplexityMeasurement(t *testing.T) {
+	c, err := ParseOpenAPI([]byte(hallContract))
+	if err != nil {
+		t.Fatal(err)
+	}
+	ops := c.Operations()
+	if len(ops) != 4 {
+		t.Errorf("operations = %v, want 4", ops)
+	}
+}
+
+func TestEmptyContractRefused(t *testing.T) {
+	if _, err := ParseOpenAPI([]byte(`openapi: "3.1.0"`)); err == nil {
+		t.Error("a contract declaring no paths was accepted")
+	}
+}

workplans/FLUID-WP-0003-deterministic-data-plane.md

@@ -4,7 +4,7 @@ type: workplan
 title: "Deterministic data plane (Blueprint Phase A)"
 domain: infotech
 repo: fluid-core
-status: active
+status: done
 owner: worsch
 topic_slug: fluid-core
 created: "2026-09-04"
@@ -64,7 +64,7 @@ read from routing policy the router does not author.
 
 ```task
 id: FLUID-WP-0003-T04
-status: todo
+status: done
 priority: high
 state_hub_task_id: "70bae578-d3e3-5a00-b5cd-4c363bc5b473"
 ```

workplans/FLUID-WP-0007-conformance-and-self-validation.md

@@ -4,7 +4,7 @@ type: workplan
 title: "Conformance suite and self-validation"
 domain: infotech
 repo: fluid-core
-status: active
+status: done
 owner: worsch
 topic_slug: fluid-core
 created: "2026-09-04"
@@ -25,7 +25,7 @@ here runs in CI with no human steps and no external services.
 
 ```task
 id: FLUID-WP-0007-T01
-status: todo
+status: done
 priority: high
 state_hub_task_id: "95b8d512-698c-5201-8f8d-18ff0a658f2c"
 ```
@@ -38,7 +38,7 @@ reproduction of the Blueprint §33 worked example.
 
 ```task
 id: FLUID-WP-0007-T02
-status: todo
+status: done
 priority: high
 state_hub_task_id: "71724683-78be-568c-bcd4-12df97e53941"
 ```
@@ -50,7 +50,7 @@ claimed in a README.
 
 ```task
 id: FLUID-WP-0007-T03
-status: todo
+status: done
 priority: high
 state_hub_task_id: "0ac5c378-038c-5c76-b082-d4868f9bb12b"
 ```
@@ -63,7 +63,7 @@ until verified) matter most and get dedicated tests.
 
 ```task
 id: FLUID-WP-0007-T04
-status: todo
+status: done
 priority: high
 state_hub_task_id: "7af0c88f-a00e-5cad-9fb6-2a297ecfd8b3"
 ```
@@ -76,7 +76,7 @@ configuration each time.
 
 ```task
 id: FLUID-WP-0007-T05
-status: todo
+status: done
 priority: high
 state_hub_task_id: "45f70116-04f4-5150-9275-2c8023389dc9"
 ```
@@ -88,7 +88,7 @@ fitness comparison, promotion, complete audit trail.
 
 ```task
 id: FLUID-WP-0007-T06
-status: todo
+status: done
 priority: medium
 state_hub_task_id: "29ce43f9-17e5-5798-a3f3-051af97224ce"
 ```