package httpserver_test

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync/atomic"
	"testing"

	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/krow/krow-backend/go-api/internal/gateway"
	"github.com/krow/krow-backend/go-api/internal/httpserver"
	"github.com/krow/krow-backend/go-api/internal/runtime"
	"github.com/krow/krow-backend/go-api/internal/testutil"
	"github.com/krow/krow-backend/go-api/internal/tools"
)

// The run endpoint's tests.
//
// Everything here is about the SEAM rather than the runtime — the runtime has
// its own tests and they are thorough. What this file asks is the set of
// questions only the HTTP layer can answer:
//
//   - Does an unauthenticated caller get in?
//   - Does another tenant's agent look absent or forbidden? (It must look
//     absent — a 403 is a confirmation that the agent exists.)
//   - Does a bounded run answer like a failure or like a run?
//   - Does a pending confirmation reach the client in a shape it can act on?
//   - Can one worker read another's trajectory?
//
// The model is scripted throughout. That is not a compromise: this file is
// about status codes and response shapes, and a live model would make it slow,
// non-deterministic and impossible to run without a credential.

/* ── Fixtures ───────────────────────────────────────────────────────────── */

// stubGateway answers with whatever it was given.
type stubGateway struct {
	text  string
	calls []gateway.ToolCall
	err   error
	sent  int
}

func (s *stubGateway) Complete(_ context.Context, _ gateway.Request) (*gateway.Response, error) {
	s.sent++
	if s.err != nil {
		return &gateway.Response{Model: "stub"}, s.err
	}
	if len(s.calls) > 0 && s.sent == 1 {
		return &gateway.Response{
			ToolCalls: s.calls, StopReason: "tool_use", Model: "stub",
			Usage: gateway.Usage{InputTokens: 400, OutputTokens: 30},
		}, nil
	}
	return &gateway.Response{
		Text: s.text, StopReason: "end_turn", Model: "stub",
		Usage: gateway.Usage{InputTokens: 500, OutputTokens: 40},
	}, nil
}

// publishAgent writes a runnable agent definition.
func publishAgent(t *testing.T, pool *pgxpool.Pool, orgID, userID, id string, toolNames ...string) {
	t.Helper()
	var toolBlock string
	if len(toolNames) > 0 {
		toolBlock = "tools:\n"
		for _, n := range toolNames {
			toolBlock += "  - " + n + "\n"
		}
	}
	md := fmt.Sprintf(`---
id: %s
name: Test Agent
description: An agent for the run endpoint's tests
status: published
version: 1
pages:
  - control-center
reasoning: balanced
%s---

## Instructions
Answer the question.
`, id, toolBlock)

	if _, err := pool.Exec(context.Background(), `
		INSERT INTO agent_definitions
		       (definition_id, org_id, visibility, created_by, markdown, status, version, name, description, pages)
		VALUES ($1::text, $2::uuid, 'organization', $3::uuid, $4::text, 'published', 1,
		        'Test Agent', 'An agent for tests', ARRAY['control-center'])`,
		id, orgID, userID, md); err != nil {
		t.Fatalf("publish agent %s: %v", id, err)
	}
}

// seedOrgAdmin creates a fresh tenant and an admin user inside it.
//
// A tenant per test, not the seeded one. The cross-tenant assertions below need
// two organizations that genuinely do not know about each other, and reusing
// the fixture's org for one of them would make "another tenant" mean "the same
// tenant with a different user".
func seedOrgAdmin(t *testing.T, h *testutil.Harness) (orgID, userID string) {
	t.Helper()
	slug := fmt.Sprintf("runs-%d-%s", orgCounter.Add(1), t.Name())
	slug = strings.ToLower(strings.NewReplacer("/", "-", "_", "-", " ", "-").Replace(slug))
	if len(slug) > 60 {
		slug = slug[:60]
	}
	if err := h.Pool.QueryRow(context.Background(),
		`INSERT INTO organizations (name, slug) VALUES ($1, $2) RETURNING id::text`,
		slug, slug).Scan(&orgID); err != nil {
		t.Fatalf("create org: %v", err)
	}
	userID = newUserWithRole(t, h.Pool, orgID,
		fmt.Sprintf("owner-%s@runs.test", slug), "admin")
	return orgID, userID
}

// orgCounter keeps fixture slugs unique. Emails and slugs are globally unique,
// so two tenants in one test collide without it.
var orgCounter atomic.Int64

// runServer builds a server whose runtime is driven by a scripted gateway.
func runServer(t *testing.T, h *testutil.Harness, gw gateway.Gateway, reg *tools.Registry) *httpserver.Server {
	t.Helper()
	engine := runtime.NewEngine(h.Pool, runtime.WithAgentExecutor(
		runtime.NewModelExecutor(gw, runtime.NewPostgresSink(h.Pool), reg),
	))
	return newServer(t, h, nil, httpserver.WithAgentEngine(engine))
}

// postRun calls the run endpoint as one actor.
func postRun(t *testing.T, handler http.Handler, a actor, agentID, body string) (int, map[string]any) {
	t.Helper()
	req, err := http.NewRequest("POST",
		"/api/v1/agents/"+agentID+"/runs", strings.NewReader(body))
	if err != nil {
		t.Fatal(err)
	}
	req.Header.Set("Content-Type", "application/json")
	if a.cookie != nil {
		req.AddCookie(a.cookie)
	}
	return doJSON(t, handler, req)
}

func doJSON(t *testing.T, handler http.Handler, req *http.Request) (int, map[string]any) {
	t.Helper()
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)
	var body map[string]any
	if rec.Body.Len() > 0 {
		if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
			t.Fatalf("response was not JSON: %s", rec.Body.String())
		}
	}
	return rec.Code, body
}

/* ── The endpoint exists at all ─────────────────────────────────────────── */

func TestTheRunRoutesAreAbsentWithoutARuntime(t *testing.T) {
	// A deployment with no model credential does not serve agents. Registering
	// the routes anyway would accept runs and fail every one at the gateway —
	// an outage shaped like a feature. 404 says "this deployment does not do
	// that", which is true; 500 would say "this deployment is broken", which is
	// not.
	h := testutil.New(t)
	srv := newServer(t, h, nil) // no WithAgentEngine, no API key
	handler := srv.Handler()

	orgID, adminID := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, orgID, adminID, "test-agent")
	admin := signInAs(t, handler, h.Pool, orgID, "admin", "admin@runs.test", "admin")

	code, _ := postRun(t, handler, admin, "test-agent", `{"input":"hello"}`)
	if code != http.StatusNotFound {
		t.Errorf("status %d without a runtime, want 404", code)
	}
}

func TestAnUnauthenticatedRunIsRefused(t *testing.T) {
	h := testutil.New(t)
	srv := runServer(t, h, &stubGateway{text: "hello"}, nil)
	handler := srv.Handler()

	code, _ := postRun(t, handler, actor{}, "test-agent", `{"input":"hello"}`)
	if code != http.StatusUnauthorized {
		t.Errorf("status %d for an unauthenticated run, want 401", code)
	}
}

/* ── A completed run ────────────────────────────────────────────────────── */

func TestACompletedRunAnswersWithItsOutputAndCost(t *testing.T) {
	h := testutil.New(t)
	srv := runServer(t, h, &stubGateway{text: "Twelve events, mostly logins."}, nil)
	handler := srv.Handler()

	orgID, adminID := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, orgID, adminID, "test-agent")
	admin := signInAs(t, handler, h.Pool, orgID, "admin", "admin@runs.test", "admin")

	code, body := postRun(t, handler, admin, "test-agent", `{"input":"what happened?"}`)
	if code != http.StatusOK {
		t.Fatalf("status %d: %v", code, body)
	}
	if body["termination"] != "Completed" {
		t.Errorf("termination = %v, want Completed", body["termination"])
	}
	if body["output"] != "Twelve events, mostly logins." {
		t.Errorf("output = %v", body["output"])
	}
	if body["runId"] == nil || body["runId"] == "" {
		t.Error("a run came back with no id; nothing can point at its trajectory")
	}
	// Token accounting reaches the client. A caller paying for runs should be
	// able to see what one cost without reading a log.
	usage, _ := body["usage"].(map[string]any)
	if usage == nil || usage["totalTokens"] == nil {
		t.Errorf("no usage in the response: %v", body)
	}
	// A completed run carries no user-facing message: the output IS the answer.
	if msg, ok := body["message"].(string); ok && msg != "" {
		t.Errorf("a completed run carried a message: %q", msg)
	}
}

/* ── The denial rules ───────────────────────────────────────────────────── */

func TestAnotherTenantsAgentIsAbsentRatherThanForbidden(t *testing.T) {
	// §8's rule about denials applies to agents as much as to rows. If "exists
	// but not yours" answered 403 and "no such agent" answered 404, the
	// endpoint would be a way to enumerate other tenants' agents one id at a
	// time — and the agent would happily run that enumeration.
	h := testutil.New(t)
	srv := runServer(t, h, &stubGateway{text: "hello"}, nil)
	handler := srv.Handler()

	mine, mineAdmin := seedOrgAdmin(t, h)
	theirs, theirsAdmin := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, theirs, theirsAdmin, "their-agent")
	_ = mineAdmin

	admin := signInAs(t, handler, h.Pool, mine, "admin", "admin@mine.test", "admin")

	real, realBody := postRun(t, handler, admin, "their-agent", `{"input":"hi"}`)
	fake, fakeBody := postRun(t, handler, admin, "no-such-agent-at-all", `{"input":"hi"}`)

	if real != http.StatusNotFound {
		t.Errorf("another tenant's agent answered %d, want 404", real)
	}
	if fake != http.StatusNotFound {
		t.Errorf("an imaginary agent answered %d, want 404", fake)
	}
	if fmt.Sprint(realBody) != fmt.Sprint(fakeBody) {
		t.Errorf("a real-but-forbidden agent is distinguishable from an imaginary one:\n"+
			"  theirs:   %v\n  invented: %v", realBody, fakeBody)
	}
}

func TestARunWithNoInputIsRefused(t *testing.T) {
	h := testutil.New(t)
	srv := runServer(t, h, &stubGateway{text: "hello"}, nil)
	handler := srv.Handler()

	orgID, adminID := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, orgID, adminID, "test-agent")
	admin := signInAs(t, handler, h.Pool, orgID, "admin", "admin@runs.test", "admin")

	code, _ := postRun(t, handler, admin, "test-agent", `{}`)
	if code != http.StatusUnprocessableEntity {
		t.Errorf("status %d for an empty input, want 422", code)
	}
}

/* ── A pending confirmation ─────────────────────────────────────────────── */

func TestAPendingConfirmationReachesTheClientAsAQuestionNotAnError(t *testing.T) {
	// I4 arriving at the surface. A run waiting on a person is not a failure:
	// it has an id, a cost, a trajectory and a payload somebody has to read.
	// Answering it 500 would make the whole write path look broken, and the
	// client would have no token to call back with.
	h := testutil.New(t)

	var wrote int
	reg := tools.NewRegistry()
	reg.MustRegister(tools.Tool{
		Name: "assign_worker", Description: "Assigns somebody to something, for this test.",
		InputSchema: map[string]any{"type": "object"}, Effect: tools.EffectWrite,
		Confirm: func(context.Context, tools.Context, json.RawMessage) (*tools.Confirmation, *tools.Result) {
			return &tools.Confirmation{
				Title:   "Assign Maya Chen to Bar Supervisor",
				Summary: "Maya Chen will be scheduled to work Friday evening.",
			}, nil
		},
		Handler: func(context.Context, tools.Context, json.RawMessage) tools.Result {
			wrote++
			return tools.OK(map[string]any{"ok": true})
		},
	})

	gw := &stubGateway{
		text:  "done",
		calls: []gateway.ToolCall{{ID: "c1", Name: "assign_worker", Input: json.RawMessage(`{}`)}},
	}
	srv := runServer(t, h, gw, reg)
	handler := srv.Handler()

	orgID, adminID := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, orgID, adminID, "cover-agent", "assign_worker")
	admin := signInAs(t, handler, h.Pool, orgID, "admin", "admin@runs.test", "admin")

	code, body := postRun(t, handler, admin, "cover-agent", `{"input":"cover Friday"}`)

	if code != http.StatusOK {
		t.Fatalf("status %d for a pending confirmation, want 200: %v", code, body)
	}
	if body["termination"] != "ConfirmationPending" {
		t.Fatalf("termination = %v, want ConfirmationPending", body["termination"])
	}
	if wrote != 0 {
		t.Fatalf("the write ran %d times without an approval", wrote)
	}

	confirmations, _ := body["confirmations"].([]any)
	if len(confirmations) != 1 {
		t.Fatalf("%d confirmations in the response, want 1: %v", len(confirmations), body)
	}
	c, _ := confirmations[0].(map[string]any)
	if c["token"] == nil || c["token"] == "" {
		t.Error("the confirmation has no token; the client can never answer it")
	}
	if c["title"] == nil || c["title"] == "" {
		t.Error("the confirmation has nothing written on it for a person to read")
	}
	// And the client is told what to say to the user, derived here rather than
	// raised from the core.
	if msg, _ := body["message"].(string); !strings.Contains(strings.ToLower(msg), "approve") {
		t.Errorf("message = %q; it should tell the user an approval is needed", msg)
	}
}

/* ── Reading a trajectory ───────────────────────────────────────────────── */

func TestATrajectoryIsReadableByItsOwnerAndNobodyElse(t *testing.T) {
	// A trajectory holds the question that was asked and the records retrieved
	// to answer it. "Anyone in the tenant may read any run" would let every
	// worker read every colleague's conversation with an agent — including the
	// ones about them.
	h := testutil.New(t)
	srv := runServer(t, h, &stubGateway{text: "an answer"}, nil)
	handler := srv.Handler()

	orgID, adminID := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, orgID, adminID, "test-agent")

	maya := signInAs(t, handler, h.Pool, orgID, "maya", "maya@runs.test", "talent")
	dan := signInAs(t, handler, h.Pool, orgID, "dan", "dan@runs.test", "talent")
	admin := signInAs(t, handler, h.Pool, orgID, "admin", "admin@runs.test", "admin")

	code, body := postRun(t, handler, maya, "test-agent", `{"input":"my private question"}`)
	if code != http.StatusOK {
		t.Fatalf("status %d: %v", code, body)
	}
	runID, _ := body["runId"].(string)
	if runID == "" {
		t.Fatal("no run id came back")
	}

	get := func(a actor) (int, map[string]any) {
		req, _ := http.NewRequest("GET", "/api/v1/runs/"+runID, nil)
		if a.cookie != nil {
			req.AddCookie(a.cookie)
		}
		return doJSON(t, handler, req)
	}

	if code, _ := get(maya); code != http.StatusOK {
		t.Errorf("the owner could not read their own run: %d", code)
	}
	if code, _ := get(dan); code != http.StatusNotFound {
		t.Errorf("another worker read a colleague's run: %d, want 404", code)
	}
	// An operator sees the organization's runs. That is what an operator
	// console is, and it is the same reach the policy table already gives them
	// over every other resource.
	if code, _ := get(admin); code != http.StatusOK {
		t.Errorf("an operator could not read their organization's run: %d", code)
	}
}

func TestATrajectoryFromAnotherTenantIsAbsent(t *testing.T) {
	h := testutil.New(t)
	srv := runServer(t, h, &stubGateway{text: "an answer"}, nil)
	handler := srv.Handler()

	mine, mineAdmin := seedOrgAdmin(t, h)
	theirs, _ := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, mine, mineAdmin, "test-agent")

	owner := signInAs(t, handler, h.Pool, mine, "owner", "owner@mine.test", "admin")
	outsider := signInAs(t, handler, h.Pool, theirs, "outsider", "outsider@theirs.test", "admin")

	_, body := postRun(t, handler, owner, "test-agent", `{"input":"a question"}`)
	runID, _ := body["runId"].(string)

	req, _ := http.NewRequest("GET", "/api/v1/runs/"+runID, nil)
	req.AddCookie(outsider.cookie)
	code, _ := doJSON(t, handler, req)

	if code != http.StatusNotFound {
		t.Errorf("another tenant read a run: %d, want 404", code)
	}
}

/* ── Streaming ──────────────────────────────────────────────────────────── */

// streamingStub is a gateway that emits text in pieces.
type streamingStub struct {
	pieces []string
	deltas int
}

func (s *streamingStub) Complete(context.Context, gateway.Request) (*gateway.Response, error) {
	return &gateway.Response{
		Text: strings.Join(s.pieces, ""), StopReason: "end_turn", Model: "stub",
		Usage: gateway.Usage{InputTokens: 100, OutputTokens: 20},
	}, nil
}

func (s *streamingStub) Stream(_ context.Context, _ gateway.Request, onDelta func(string)) (*gateway.Response, error) {
	for _, p := range s.pieces {
		s.deltas++
		onDelta(p)
	}
	return &gateway.Response{
		Text: strings.Join(s.pieces, ""), StopReason: "end_turn", Model: "stub",
		Usage: gateway.Usage{InputTokens: 100, OutputTokens: 20},
	}, nil
}

// sseEvents pulls the JSON payloads out of an SSE body.
func sseEvents(t *testing.T, body string) []map[string]any {
	t.Helper()
	var out []map[string]any
	for _, line := range strings.Split(body, "\n") {
		line = strings.TrimSpace(line)
		if !strings.HasPrefix(line, "data:") {
			continue
		}
		payload := strings.TrimSpace(line[5:])
		if payload == "" || payload == "[DONE]" {
			continue
		}
		var e map[string]any
		if err := json.Unmarshal([]byte(payload), &e); err != nil {
			t.Fatalf("event was not JSON: %s", payload)
		}
		out = append(out, e)
	}
	return out
}

func TestAStreamedRunDeliversTextThenTheFinishedRun(t *testing.T) {
	h := testutil.New(t)
	gw := &streamingStub{pieces: []string{"Twelve ", "events, ", "mostly logins."}}
	srv := runServer(t, h, gw, nil)
	handler := srv.Handler()

	orgID, adminID := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, orgID, adminID, "test-agent")
	admin := signInAs(t, handler, h.Pool, orgID, "admin", "admin@stream.test", "admin")

	req, _ := http.NewRequest("POST", "/api/v1/agents/test-agent/runs",
		strings.NewReader(`{"input":"what happened?"}`))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "text/event-stream")
	req.AddCookie(admin.cookie)

	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status %d: %s", rec.Code, rec.Body.String())
	}
	if ct := rec.Header().Get("Content-Type"); !strings.Contains(ct, "text/event-stream") {
		t.Fatalf("Content-Type is %q, want an event stream — the response did not stream", ct)
	}

	events := sseEvents(t, rec.Body.String())
	var deltas []string
	var final map[string]any
	for _, e := range events {
		if d, ok := e["delta"].(string); ok {
			deltas = append(deltas, d)
		}
		if r, ok := e["run"].(map[string]any); ok {
			final = r
		}
	}

	if len(deltas) != 3 {
		t.Errorf("%d text deltas, want 3 — the text arrived in one piece", len(deltas))
	}
	if strings.Join(deltas, "") != "Twelve events, mostly logins." {
		t.Errorf("the deltas do not reassemble into the answer: %q", strings.Join(deltas, ""))
	}

	// The property that keeps the two paths honest: a client that ignored every
	// delta and read only the last event is where it would have been without
	// streaming at all.
	if final == nil {
		t.Fatal("no final run event; a client reading only the last event would have nothing")
	}
	if final["termination"] != "Completed" {
		t.Errorf("final termination = %v", final["termination"])
	}
	if final["output"] != "Twelve events, mostly logins." {
		t.Errorf("final output = %v", final["output"])
	}
	if final["runId"] == nil || final["runId"] == "" {
		t.Error("the final event carries no run id")
	}
}

func TestMiddlewareDoesNotSwallowFlush(t *testing.T) {
	// The bug this pins cost an hour and produced no error anywhere.
	//
	// Two middlewares wrap the ResponseWriter to record a status and to
	// intercept the mux's plain-text 404s. Both embed http.ResponseWriter,
	// which inherits Write and WriteHeader and SILENTLY DROPS every optional
	// interface underneath — Flusher among them. The SSE handler asked "can
	// this flush?", was told no, and fell back to ordinary JSON: a correct,
	// complete, entirely non-streaming response with nothing to indicate that
	// streaming had been requested and quietly refused.
	//
	// Asserted through the whole middleware stack, because testing the handler
	// alone is exactly what missed it.
	h := testutil.New(t)
	srv := runServer(t, h, &streamingStub{pieces: []string{"a", "b"}}, nil)
	handler := srv.Handler()

	orgID, adminID := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, orgID, adminID, "test-agent")
	admin := signInAs(t, handler, h.Pool, orgID, "admin", "admin@flush.test", "admin")

	req, _ := http.NewRequest("POST", "/api/v1/agents/test-agent/runs",
		strings.NewReader(`{"input":"hi"}`))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "text/event-stream")
	req.AddCookie(admin.cookie)

	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	if ct := rec.Header().Get("Content-Type"); !strings.Contains(ct, "text/event-stream") {
		t.Fatalf("Content-Type is %q — a wrapper dropped Flusher and the stream fell back to JSON", ct)
	}
	if b := rec.Header().Get("X-Accel-Buffering"); b != "no" {
		t.Errorf("X-Accel-Buffering is %q; a buffering proxy will hold the whole stream", b)
	}
}

func TestAnOrdinaryRequestIsStillNotStreamed(t *testing.T) {
	// Accept decides. A client that did not ask for a stream must not get one —
	// it would be reading SSE frames as if they were a JSON body.
	h := testutil.New(t)
	srv := runServer(t, h, &streamingStub{pieces: []string{"x"}}, nil)
	handler := srv.Handler()

	orgID, adminID := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, orgID, adminID, "test-agent")
	admin := signInAs(t, handler, h.Pool, orgID, "admin", "admin@plain.test", "admin")

	code, body := postRun(t, handler, admin, "test-agent", `{"input":"hi"}`)
	if code != http.StatusOK {
		t.Fatalf("status %d", code)
	}
	if body["termination"] != "Completed" || body["output"] != "x" {
		t.Errorf("a plain request did not get a plain answer: %v", body)
	}
}

func TestARequestedVersionReachesTheRuntime(t *testing.T) {
	// §3's pin, at the seam. The frontend sends back the version its first
	// answer carried; this asserts the field survives the request rather than
	// being quietly dropped — which would look identical from outside until
	// somebody published an edit mid-conversation.
	h := testutil.New(t)
	srv := runServer(t, h, &stubGateway{text: "answered"}, nil)
	handler := srv.Handler()

	orgID, adminID := seedOrgAdmin(t, h)
	publishAgent(t, h.Pool, orgID, adminID, "test-agent")
	admin := signInAs(t, handler, h.Pool, orgID, "admin", "admin@pin.test", "admin")

	// Version 9 has no snapshot, so the run falls back to the current
	// definition and says so — which is the observable proof the number
	// travelled: an ignored field would produce no note at all.
	code, body := postRun(t, handler, admin, "test-agent",
		`{"input":"hello","agentVersion":9}`)
	if code != http.StatusOK {
		t.Fatalf("status %d: %v", code, body)
	}
	if body["termination"] != "Completed" {
		t.Fatalf("termination = %v", body["termination"])
	}

	var runID, _ = body["runId"].(string)
	req, _ := http.NewRequest("GET", "/api/v1/runs/"+runID, nil)
	req.AddCookie(admin.cookie)
	_, traj := doJSON(t, handler, req)

	encoded, _ := json.Marshal(traj)
	if !strings.Contains(string(encoded), "version_unavailable") {
		t.Errorf("a pinned version with no snapshot left no trace in the trajectory; "+
			"the field may have been dropped: %s", truncate(string(encoded), 400))
	}
}

func truncate(s string, n int) string {
	if len(s) <= n {
		return s
	}
	return s[:n] + "…"
}