fitz-go

Reference Go client for Fitz.

The supported public API is the canonical github.com/cntryl/fitz-go/fitz package: token-provider auth, Connect/Close, State, and spec-facing domain verbs.

Public API

Import github.com/cntryl/fitz-go/fitz for the public API.

package main

import (
	"context"
	"time"

	"github.com/cntryl/fitz-go/fitz"
)

func main() {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	client := fitz.NewClient("ws://localhost:4090/ws", func(context.Context) (string, error) {
		return "your-jwt-token", nil
	}, fitz.WithReconnect(true, 250*time.Millisecond, 5))

	if err := client.Connect(ctx); err != nil {
		panic(err)
	}
	defer client.Close()

	tx, err := client.KV().Begin(ctx, "kv://realm/area/users")
	if err != nil {
		panic(err)
	}
	defer tx.Rollback(ctx)

	if err := tx.Put(ctx, []byte("user-1"), []byte(`{"name":"Alice"}`)); err != nil {
		panic(err)
	}

	value, err := tx.Get(ctx, []byte("user-1"))
	if err != nil {
		panic(err)
	}
	if value.Found {
		println(string(value.Value))
	}

	if err := tx.Commit(ctx); err != nil {
		panic(err)
	}
}

Canonical usage patterns

Use one control plane for request lifetime: context.Context.

• RPC calls use context deadlines/cancellation only.
• Schedule/Notice/Queue/Lease/Stream subscription handlers return error.
• Streaming iterators should be closed when no longer needed.

Connection lifecycle is part of the stable public API:

• Disconnected: before Connect and after an unrecoverable disconnect
• Connecting: transport dial/handshake in progress
• Connected: transport established, auth not yet settled
• Authenticating: CONNECT/auth exchange in progress
• Authenticated: ready for domain traffic
• Reconnecting: automatic reconnect loop is actively retrying
• Closed: client has been closed and will not reconnect

Reconnect guarantees:

• Automatic reconnect only runs when configured with fitz.WithReconnect(...).
• Notice, stream, lease, queue, and schedule subscriptions are restored after reconnect.
• RPC worker registrations are restored after reconnect.
• Close() is idempotent and permanently ends reconnect activity.

The broker-backed test suite verifies those guarantees through a live disconnect proxy rather than by closing one client and creating another.

RPC timeout pattern:

callCtx, cancelCall := context.WithTimeout(ctx, 2*time.Second)
defer cancelCall()

iter, err := client.RPC().Call(callCtx, "rpc://realm/area/echo", []byte("ping"))
if err != nil {
	panic(err)
}
defer iter.Close()

for iter.Next() {
	_ = iter.Value()
}
if err := iter.Err(); err != nil {
	panic(err)
}

Schedule subscription handler pattern:

sub, err := client.Schedule().Subscribe(ctx, "schedule://realm/area/resource/run", func(ctx context.Context, n fitz.ScheduleNotification) error {
	_ = n
	return nil
})
if err != nil {
	panic(err)
}
defer sub.Unsubscribe()

Stream replay pattern:

filter := &fitz.StreamFilterSet{Clauses: []fitz.StreamFilterClause{{Kind: fitz.StreamFilterEquals, Value: "proj.alpha"}}}

records, err := client.Stream().Read(ctx, "stream://realm/area/events", 0, 100, &fitz.StreamReadOptions{Filter: filter})
if err != nil {
	panic(err)
}
defer records.Close()

page, err := client.Stream().ReadPage(ctx, "stream://realm/area/events", 0, 100, &fitz.StreamReadOptions{Filter: filter})
if err != nil {
	panic(err)
}

// Read keeps the compatibility shape and yields event records only.
// ReadPage exposes filtered markers plus cursor progression across hidden offsets.
_ = page.Cursor.LastResourceOffset

Architecture

• fitz/: public client, public domain wrappers, public types
• internal/core/client: top-level client implementation
• internal/core/connection: CONNECT lifecycle, request correlation, notify dispatch
• internal/core/transport: TCP and WebSocket transports
• internal/protocol: frame encoding and message type constants
• internal/domains/*: spec-aligned domain clients
• test/: broker-backed integration coverage

Broker-backed tests

Integration tests target a running Fitz broker and are opt-in via the integration build tag.

Use the local compose stack in compose.yml:

docker compose -f compose.yml up -d

That starts:

• fitz-auth on localhost:4091 and ws://localhost:4090/ws
• fitz-anon on localhost:4191 and ws://localhost:4190/ws

Anonymous broker example:

export FITZ_BROKER_TCP_ADDR=localhost:4191
export FITZ_BROKER_WS_ADDR=ws://localhost:4190/ws
go test ./...

Run the broker-backed acceptance suite explicitly when you want the full end-to-end matrix:

go test -tags=integration ./test

Auth-required broker example:

export FITZ_BROKER_TCP_ADDR=localhost:4091
export FITZ_BROKER_WS_ADDR=ws://localhost:4090/ws
export FITZ_BROKER_AUTH_REQUIRED=true
export FITZ_BROKER_JWT_HMAC_SECRET=test-secret-key
export FITZ_BROKER_JWT_AUDIENCE=fitz
go test ./...

Error-path coverage in the broker-backed suite includes unauthorized operations across all 7 domains, plus invalid KV range and invalid cron cases.

Focused reconnect validation is usually more useful than a blanket go test -tags=integration ./test run in this repo. The high-signal reconnect slices are:

go test -tags=integration ./test -run "TestShould(RestoreNoticeSubscriptionGivenLiveDisconnectWhenReconnectEnabled|RestoreWorkerRegistrationGivenLiveDisconnectWhenReconnectEnabled|RestoreAvailabilitySubscriptionGivenLiveDisconnectWhenReconnectEnabled|RestoreCommitSubscriptionGivenLiveDisconnectWhenReconnectEnabled|RestoreLeaseSubscriptionGivenLiveDisconnectWhenReconnectEnabled)"
go test -tags=integration ./test -run "TestShouldRestoreScheduleSubscriptionGivenLiveDisconnectWhenReconnectEnabled"
go test ./test/conformance/... -run "TestConformanceSuite/(CS-009_disconnect_during_request|CS-010_reconnect_behavior)"

Those tests use the shared live-disconnect seam in test/fixture/proxy.go to exercise real disconnect, reconnect, and restore behavior against a running broker.

Benchmark thresholds and evidence policy are documented in docs/PERF_RESULTS.md; treat that report as the source of truth for hot-path gates.

Run the full suite with:

go test ./...
go test -tags=integration ./test

Or use the repo-local verification script:

./scripts/verify.ps1

Run pedantic lint and style checks directly with golangci-lint v2:

go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@latest
$(go env GOPATH)/bin/golangci-lint version
$(go env GOPATH)/bin/golangci-lint run --config .golangci.yml

Run the repo-local spec-compliance conformance suite with:

go test -v -timeout 120s ./test/conformance/... -run TestConformanceSuite

Local performance workflow

Use direct go test and go tool pprof commands while optimizing hot paths.

The benchmark gates and evidence policy are summarized in docs/PERF_RESULTS.md.

Run hotpath micro-benchmarks:

go test -run=^$ -bench='Benchmark(EncodeFrame|DecodeFrame|EncodeFrameWithPayloadWriter|MuxDispatchResponse|RegisterRequest|ConcurrentDispatch|WriteFrame|ReadFrame|WriteWSFrame|ReadWSFrame|WriteU64|WriteU32|WriteString|WriteBytes)' -benchmem -count=5 -benchtime=2s ./internal/protocol ./internal/core/encoding ./internal/core/connection ./internal/core/transport

Run domain-level benchmarks:

go test -run=^$ -bench=Benchmark -benchmem -count=5 -benchtime=2s ./internal/domains/...

Run the public hotpath suite:

go test -run=^$ -bench='Benchmark(HandleRPCResponseHotPath|QueueReserveHotPath|QueueCompleteHotPath|StreamBeginHotPath|StreamAppendHotPath|ScheduleCreateHotPath|ScheduleCancelHotPath|SubscriptionRegistryRestore|KVTransactionLoopback|NoticePublishHotPath|FrameEncode|RPCCorrelation1KInFlight)' -benchmem -count=5 -benchtime=2s ./bench ./internal/domains/rpc

bench/hotpath_bench_test.go holds the cross-domain hotpaths, and internal/domains/rpc/rpc_test.go keeps the RPC dispatch benchmark next to the implementation.

Collect CPU and memory profiles for one benchmark target:

go test -run=^$ -bench=BenchmarkMuxDispatchResponse -benchmem -count=1 -cpuprofile=cpu.prof -memprofile=mem.prof ./internal/core/connection
go tool pprof -top cpu.prof
go tool pprof -top mem.prof

When you need a regression diff, capture two local benchmark runs and compare them with benchstat:

go test -run=^$ -bench=. -benchmem -count=3 \
	github.com/cntryl/fitz-go/bench \
	github.com/cntryl/fitz-go/internal/domains/rpc \
	github.com/cntryl/fitz-go/internal/protocol \
	github.com/cntryl/fitz-go/internal/core/connection \
	github.com/cntryl/fitz-go/internal/core/encoding \
	github.com/cntryl/fitz-go/internal/core/transport \
	github.com/cntryl/fitz-go/internal/domains/stream \
	github.com/cntryl/fitz-go/internal/domains/kv \
	github.com/cntryl/fitz-go/internal/domains/notice \
	github.com/cntryl/fitz-go/internal/domains/schedule > before.txt
go test -run=^$ -bench=. -benchmem -count=3 \
	github.com/cntryl/fitz-go/bench \
	github.com/cntryl/fitz-go/internal/domains/rpc \
	github.com/cntryl/fitz-go/internal/protocol \
	github.com/cntryl/fitz-go/internal/core/connection \
	github.com/cntryl/fitz-go/internal/core/encoding \
	github.com/cntryl/fitz-go/internal/core/transport \
	github.com/cntryl/fitz-go/internal/domains/stream \
	github.com/cntryl/fitz-go/internal/domains/kv \
	github.com/cntryl/fitz-go/internal/domains/notice \
	github.com/cntryl/fitz-go/internal/domains/schedule > after.txt
benchstat before.txt after.txt

Install benchstat once if needed with go install golang.org/x/perf/cmd/benchstat@latest.

Protocol source of truth

This repo does not maintain an independent copy of the protocol specification. Use the canonical server-owned docs referenced from:

• docs/CLIENT_SPEC.md
• docs/CLIENT_ACCEPTANCE_CRITERIA.md

Documentation

• docs/README.md
• docs/CLIENT_SPEC.md
• docs/CLIENT_ACCEPTANCE_CRITERIA.md

Message type and conformance coverage map

This is a lightweight map from implemented message-type ranges to conformance scenario coverage in test/conformance.

Domain	Message type range	Key message types (examples)	Conformance scenarios
Control	1	CONNECT	CS-001, CS-002
KV	100-108	BEGIN, COMMIT, GET, PUT, INSERT, SCAN	CS-001, CS-003, CS-005, CS-006, CS-014, CS-015
Queue	200, 202-204, 207-209	ENQUEUE, RESERVE, EXTEND, COMPLETE, SUBSCRIBE	CS-016 (enqueue/reserve/complete lifecycle)
RPC	300-304	SUBSCRIBE_WORKER, REQUEST, RESPONSE	CS-004, CS-006, CS-007, CS-008, CS-009
Lease	400-403, 407-409	ACQUIRE, RENEW, RELEASE, QUERY, NOTIFY	CS-017 (acquire/contention/release lifecycle)
Notice	500-504	PUBLISH, SUBSCRIBE, UNSUBSCRIBE, NOTIFY	CS-018 (subscribe/publish/deliver/unsubscribe)
Stream	600-609	BEGIN, APPEND, COMMIT, READ, SUBSCRIBE	CS-011, CS-012, CS-013
Schedule	700-705	CREATE, CANCEL, LIST, SUBSCRIBE, NOTIFY	CS-019 (create/subscribe/cancel lifecycle)

Notes:

• Queue 201 (ENQUEUE_BATCH) is reserved by spec and intentionally not implemented.
• CS-016–CS-019 are Go client additions beyond the 15-scenario cross-language spec, closing coverage gaps for the four subscribe/notify-pattern domains.
• Schedule fire delivery (actual cron trigger) is covered in the integration suite (TestShouldDeliverScheduleNotificationGivenLiveBrokerWhenScheduleFires), which requires up to 90 s for the next * * * * * tick.
• Conformance scenarios focus on cross-language semantic parity; integration tests provide additional domain-specific operation coverage.