go

name	go
description	Go coding and lint guardrails for Invowk. Use whenever Codex creates, edits, reviews, refactors, or tests Go code (*.go), changes Go linters or formatters, fixes golangci-lint/goplint/staticcheck/revive/decorder/funcorder/gocritic/modernize/perfsprint/wrapcheck/errcheck errors, or touches Go package architecture.

Go

Apply this skill before editing Go and again before final verification. It captures the project patterns most likely to fail make lint, make check-baseline, commit hooks, or review.

Mandatory Flow

1. Identify the touched package role: CLI adapter, app service/domain, infrastructure adapter, public pkg/*, test, or tool.
2. Preserve hexagonal boundaries: adapters parse/render/wire; services return typed results/errors/diagnostics; domain packages do not write terminal UI.
3. Keep declaration order as const, var, type, func, with one block of each kind per file when needed. Place exported funcs before unexported funcs.
4. Thread caller contexts through all I/O, subprocess, HTTP, server lifecycle, discovery, runtime, and long-running operations.
5. Use project value types and Validate() contracts for domain data. Consult invowk-typesystem when adding or changing value types.
6. Before finishing, run the narrow relevant go test command, then follow .agents/rules/checklist.md for completion gates. For Go edits that usually includes make tidy, make lint, make test, make check-baseline, and make check-file-length unless the user explicitly scoped the work to a read-only review.

File Shape

Use this order:

// SPDX-License-Identifier: MPL-2.0

// Package name explains the package contract.
package name

import (...)

const (...)

var (...)

type (...)

func Exported() {}

func unexported() {}

• Use doc.go for multi-paragraph package documentation.
• Keep only one package comment per package. If doc.go exists, other files should have only package name.
• Import groups must be standard library, external modules, then github.com/invowk/invowk/....
• Split large files with this deterministic protocol: move declarations exactly once, delete originals in the same patch, clean imports, run go build ./path/to/package/..., then run targeted tests for that package.

Errors

• Sentinel errors must use constant-backed messages.

const notFoundErrMsg = "resource not found"

var ErrNotFound = errors.New(notFoundErrMsg)

• Error variables start with Err; error types end with Error.
• Wrap external or boundary errors with context: fmt.Errorf("load config: %w", err).
• Use errors.AsType[T] in production code, not errors.As.
• Use errors.New instead of fmt.Errorf when there is no formatting or wrapping.
• Never return nil error after checking a non-nil error.
• Do not discard errors unless the function is allowlisted or the discard is deliberate, commented, and accepted by lint.
• For resources, prefer named returns and deferred close aggregation. For best-effort cleanup, log or comment the intentional discard.

Context And Processes

• context.Context is the first parameter.
• Use cmd.Context() at Cobra boundaries and pass ctx context.Context into helpers.
• Use http.NewRequestWithContext, exec.CommandContext, and context-aware engine/server calls.
• For long-running subprocesses, set cmd.WaitDelay when cancellation or pipe-draining can otherwise hang.
• When capturing subprocess stdout/stderr that may be inspected before Run/Wait has completed, do not expose a raw bytes.Buffer; use a synchronized writer/snapshot type or wait for the process first.
• context.Background() is only for true roots, nil fallback documented on an options struct, bounded availability probes, TestMain, or independent shutdown after caller cancellation.
• Tests should default to t.Context().

Validation And Value Types

• Constructors or factories for structs with invariants should call Validate() before returning.
• Never ignore Validate() results.
• A struct Validate() must delegate to every field that has Validate(). For maps/slices of validating values, create a named collection type with its own Validate() when that makes delegation explicit.
• Validate() methods need production call sites; test-only validators are misleading.
• Keep Invalid*Error wrappers and sentinel Unwrap() behavior consistent.
• Avoid bare primitives in domain structs, params, and returns unless the value is a real boundary/display/free-form exception already documented in tools/goplint/exceptions.toml or justified with //goplint:ignore -- ....

Lint Traps

• decorder/funcorder: do not add extra const, var, or type blocks; group related declarations with type (...), etc.
• revive exported: every exported type, const, var, function, and method needs a meaningful doc comment starting with the identifier.
• revive context-as-argument: context first, always.
• wrapcheck: wrap errors from external packages unless the config explicitly ignores that signature/package.
• errcheck: check returned errors. In tests, use helpers or assertions rather than blank identifiers.
• nolintlint: avoid //nolint; if unavoidable, name the exact linter and add a reason.
• forbidigo: production code uses errors.AsType[T].
• modernize: prefer Go 1.26 forms such as slices.Contains, strings.SplitSeq in range-only loops, and fmt.Appendf instead of []byte(fmt.Sprintf(...)).
• gocritic rangeValCopy: range over map/slice keys or indices when values are large structs.
• gocritic/predeclared: do not shadow builtins such as len, cap, new, make, copy, or append.
• perfsprint: use errors.New, strconv, or direct conversions where formatting is unnecessary.
• staticcheck: remove redundant struct literals and unnecessary conversions.
• unconvert: avoid conversions that do not change type.
• exhaustive: list every enum value in switches, even when a case matches the default behavior.
• tagliatelle: JSON tags are snake_case; add mapstructure tags for Viper config structs.
• sloglint: use key-value logging with snake_case keys.
• nosprintfhostport: use net.JoinHostPort.
• bodyclose: close HTTP response bodies.
• makezero: do not append into slices created with non-zero length unless that is really intended.
• depguard: no io/ioutil; tests do not use testify.
• mnd: name non-obvious numbers, except common ignored cases in .golangci.toml and test data.
• goconst: repeated production strings usually become constants.
• iface: avoid interfaces until they express a real port/contract. Keep them small and consumed by callers.

Comments

• Comments document semantics: intent, ownership, lifecycle, side effects, security, precedence, and invariants.
• Do not restate obvious syntax.
• Comment subtle ordering, fallback, cleanup, or race-sensitive behavior.
• Guardrail tests scan comments with raw substring matching. Refer to removed or forbidden APIs indirectly; do not paste prohibited call expressions into comments.

Tests

• Use standard testing, not testify.
• Test helpers call t.Helper() at the beginning.
• Use t.Context(), t.TempDir(), t.Setenv(), and t.Chdir() where applicable.
• When tests exercise libraries that write relative artifacts, isolate with t.Chdir(t.TempDir()).
• For Go test execution strategy, race detector behavior, platform flakes, or CLI testscript guidance, also use go-testing and the relevant platform testing skill.

Linter Config Changes

• Keep .golangci.toml documented when adding, removing, or configuring a linter.
• Never disable decorder or funcorder.
• Exclusions must explain why the policy exception is acceptable.
• After linter config changes, run make lint and the relevant hook/check (make check-baseline for goplint-sensitive changes).
• For tools/goplint or goplint behavior changes, also read tools/goplint/AGENTS.md and use its current gate list; do not rely on this skill to enumerate every goplint semantic, IFDS, CFG, race, repeat, benchmark, or baseline check.