Go

Pure Go codecs for Bluetooth Fitness Machine Service bytes. Module: github.com/deancochran/ftms/packages/go, package name: ftms, minimum Go: 1.24. No runtime dependencies beyond the standard library. No BLE, cgo, timers, logging, background goroutines, or control authority.

Integrate through the consumer adapter seam: transport conversion, BLE/session lifecycle, retries, subscriptions, UI/application policy and control safety remain outside this protocol package.

Version 0.1.0: raw codecs and static capability interpretation. The pre-1.0 interface may change in minor releases. See coverage, verification, and release gates. Publication evidence is recorded in the canonical release matrix.

Select the latest release for your application, then retain go.mod and go.sum:

go get github.com/deancochran/ftms/packages/go@latest

To reproduce the recorded release specifically, use go get github.com/deancochran/ftms/packages/go@v0.1.0. Existing constraints may affect resolution; inspect the selected version before adopting changes.

Implemented

• Bidirectional Feature values, all five Supported Ranges, and all six measurement families.
• All 21 Control Point requests and Control Point responses, in both directions.
• Machine Status and Training Status, in both directions.
• Range inspection and normalized range values.
• Explicit malformed-input, unavailable-field, and unknown-bit evidence.
• Static capability interpretation of caller-owned discovery snapshots, including full Bluetooth-base UUID matching, C.7 evidence, ranges, diagnostics, and all 21 Control Point operation prerequisites. It never performs I/O or says that a caller is authorized to execute an operation.

Normalized measurement views, record planning, and record assembly remain pending. More Data is preserved, not assembled.

Example

import ftms "github.com/deancochran/ftms/packages/go"

reading, err := ftms.DecodeMeasurement(
    ftms.IndoorBike,
    []byte{0, 0, 0x10, 0x0e},
    ftms.MeasurementOptions{},
)
// Handle err and reading.Diagnostics before using values.
// reading.Values[ftms.Speed] is 3600 raw hundredths of km/h.
_ = err
_ = reading

See example_test.go for an executable example. The byte slice is synthetic, not a physical-device capture.

Static capability evidence

InterpretCapabilities(snapshot, options) evaluates caller-supplied observations without discovering characteristics or reading a device. It preserves missing, failed, malformed, duplicate, and contradictory evidence separately. Its complete reports pass all 63 canonical capability cases, including C.7 property rules.

See the capability guide and the executable ExampleInterpretCapabilities for snapshot construction and interpretation. PrerequisiteSatisfied is a static protocol result, not permission to execute.

Raw values and errors

Measurement.Values is indexed by typed MeasurementField constants. Map membership means a complete available field was decoded; a true entry in Unavailable means a complete defined sentinel was observed. Neither means physical zero. Absence from both maps means absent or incomplete bytes, resolved using flags and diagnostics. BytesRead ends after the last complete field.

Raw values use wire units: speed is hundredths of km/h; cadence and stroke rate are half-units per minute; signedness and scaling otherwise depend on the characteristic and explicit format. No automatic clamping or quantization occurs. Control request operands are ordered raw integers in the specification’s wire order, not normalized physical values. Request opcodes are 0x00 through 0x14.

Measurement decoders return errors for invalid arguments or missing flag words, but preserve partial measurements with diagnostics for truncated payload fields. Status decoders return diagnostic values for malformed input. Feature, range, and request decoders return ErrLength, ErrKind, or ErrRange as applicable. Control response decoding can explicitly retain unexpected trailing-parameter diagnostics. Do not treat a nil error alone as proof that a record is canonical.

Training text is a Go string that retains original bytes even if invalid UTF-8; check its diagnostics before displaying it. Such evidence cannot be encoded as a canonical Training Status. Decoders do not mutate or retain caller byte slices. Returned maps and slices belong to the caller; concurrent mutation requires caller synchronization.

Format selections are independent

Domain	Zero-value options	Explicit alternative
Resistance range	Three-byte ResistanceUint8Whole	ResistanceSint16Tenths
Control resistance	Corrected ControlResistanceSigned16Tenths	ControlResistanceUint8Tenths
Raw resistance measurement	Legacy MeasurementResistanceUint8	MeasurementResistanceSigned16Tenths
Treadmill pace	16-bit	TreadmillPaceUint8: true

The raw measurement default follows the existing raw corpus. Select the signed measurement format explicitly when that is the caller’s intended wire profile. No format is inferred from bytes, range values, device names, or capability flags. Decoded range/measurement values retain format provenance; their encoders require the same selection. Alternative range candidates do not establish intended format, units, or permission to control equipment.

Contributor verification

From this directory, ordinary package checks require only Go:

go vet ./...
go test -race ./...
go build ./...

Full checkout verification additionally requires Python with the pinned contributor-only validator (scripts/requirements.txt):

bash scripts/verify.sh

It validates canonical schemas and capability template expansions, executes shared fixtures directly (including all 63 capability reports), runs the structural matrix, and installs a module zip into an isolated consumer without replace, a workspace, or sibling fixtures. Consumers do not need Python.

The conformance build tag is checkout-only and fails when canonical assets are missing. Ordinary installed-module tests do not depend on shared/.

Discovery, subscriptions, control ownership, procedure timing, bonding, and physical safety remain the application’s responsibility. A valid encoded request does not authorize its transmission.