[boeboe]

What changed

• version prints one line: modbusctl <version> (tag <tag>, commit <sha>, built <date>, <go>, <goos>/<goarch>). The tag part is left out when the build has no tag; the version has no leading v. A development build reports dev and takes the commit from the Go VCS stamp (-dirty for a modified tree); go install …@vX.Y.Z reports that version. New package internal/buildinfo; main.* stays the ldflags target.
• version --json (new flag) and MODBUSCTL_FORMAT=json: one JSON object, keys name, version, tag, commit, built, go, platform in this order, always present. MODBUSCTL_FORMAT=text|table print the text line.
• Completion: completion already offered bash, zsh, fish and PowerShell (tested via __complete). Every flag that takes a value now has a completion function (a walk test fails otherwise). New value completion: --function of the capture commands (0-4), --missing, --before-first, --retry-timeout, --data-bits, --stop-bits, --baud, --family and --value-kind (from the codec registry), --url (schemes), --interface (network interfaces); file completion by extension for --input (mbcap/jsonl/csv), --profile/--blocks-file (json), --tls-ca/--tls-cert/--tls-key (pem…); --output completes any file; numbers, durations and addresses complete no file names. Commands without positional arguments complete no file names.
• make build: COMMIT is the full SHA. Release workflow ldflags were already correct (-X main.version/tag/commit/buildDate).
• README (version section, completion sentence), docs/json-output.md (version object), RELEASE.md v3.6.0, e2e test.

Follow-up commit (brief amendments)

• The OT Fabric libraries (github.com/otfabric/go-* modules of the build info, sorted) follow built … in the text line, and libraries ([{"name","version"}], [] when none) sits between built and go in the JSON.
• Pseudo-versions and +dirty module versions report dev.
• Makefile: VERSION and TAG only when HEAD is exactly on a tag; otherwise empty and the binary reports dev (archive names fall back to dev).

Before / after

Before (v3.5.1 built with release-style ldflags):

modbusctl version: v3.5.1
tag:         v3.5.1
commit:      1802d0f9afe8642d1e278120b76fcdfac967cb9e
build date:  2026-11-05T15:41:49Z

(version --json: error: unknown flag: --json)
After (release-style ldflags):

modbusctl 3.6.0 (tag v3.6.0, commit ae76784522f7853b6f19326b2b30bd6b92636e10, built 2026-11-07T12:00:00Z, go-modbus 1.11.1, go-modbus-capture 0.1.0, go-serial 0.2.1, go1.27.3, darwin/arm64)
{"name":"modbusctl","version":"3.6.0","tag":"v3.6.0","commit":"ae76784522f7853b6f19326b2b30bd6b92636e10","built":"2026-11-07T12:00:00Z","libraries":[{"name":"go-modbus","version":"1.11.1"},{"name":"go-modbus-capture","version":"0.1.0"},{"name":"go-serial","version":"0.2.1"}],"go":"go1.27.3","platform":"darwin/arm64"}

Plain go build (a clean checkout off a tag):

modbusctl dev (commit ae76784522f7853b6f19326b2b30bd6b92636e10, built unknown, go-modbus 1.11.1, go-modbus-capture 0.1.0, go-serial 0.2.1, go1.27.3, darwin/arm64)

Tests run

• make check (fmt-check, vet, staticcheck, golangci-lint, govulncheck, tests, coverage 96.5%), make e2e, go test -race ./cmd/... ./internal/buildinfo
• Binary: version, version --json, MODBUSCTL_FORMAT=json version, completion bash|zsh|fish|powershell, __complete completion "", __complete capture decode --input "", __complete server replay --missing "", __complete client read --url t

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 93.84615% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cmd/flag_completion.go	84.00%	8 Missing ⚠️

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