[emmanuelgautier]

Summary

• Adds telemetryx.Instrument(root, version, apiKey, opts...), which wires argvio-go's cobrasdk into a CLI's whole Cobra tree (command, flag names, exit code, latency, help usage, sessions). It sits alongside telemetryx.New, so the existing OTel metrics and traces are unchanged.
• apiKey is each CLI's own public_ingest Argvio key, so every CLI lands in its own Argvio tenant. The telemetry.cerberauth.com collector forwards it as is.
• Adds telemetryx.Exit / telemetryx.Fatal to use instead of os.Exit / log.Fatal inside commands. Those skip the hooks that record a command's outcome and the deferred flush, so such runs were never reported.
• Error categories and reasons. Fatal and errors returned from RunE are classified by a default classifier (timeout, canceled, network, missing or unreadable file and Cobra usage errors are user; the rest unknown). telemetryx.Reason(err, "no-token") and telemetryx.Classified(err, category, reason) attach a fixed-vocabulary reason where a CLI knows the cause, and WithClassifier replaces the default.
• Product signals. telemetryx.Counter(ctx, name, n, label) adds to an Argvio counter and telemetryx.Feature(ctx, name) records a capability as used. telemetryx.Vocab(value, allowed...) limits a value read from the CLI's input to a list written in code.
• Counters are accepted at the anonymous tier, so they are also sent from CI. Their names and labels must be fixed identifiers, never user input; the doc comment says so.
• Interactive runs report at the Basic tier and CI runs at Anonymous. --sqa-opt-out, DO_NOT_TRACK and ARGVIO_DISABLED disable everything. New now honors DO_NOT_TRACK too.
• Requires argvio-go v0.3.0 or later (this branch uses v0.4.0).

Test plan

• go build ./..., go vet ./..., go test ./..., golangci-lint run --new-from-rev=origin/main (0 issues)
• A test points the client at a local collector and checks a counter and a feature reach it, and that an invalid counter name is dropped. It fails when telemetry is disabled.
• Used by the 8 Go CLIs on their feat/argvio branches.

The CLI PRs depend on this one. Please merge it first.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.88889% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 89.21%. Comparing base (ae6bcf1) to head (b46113e).

Files with missing lines	Patch %	Lines
telemetryx/classify.go	97.05%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #61      +/-   ##
==========================================
+ Coverage   87.42%   89.21%   +1.79%     
==========================================
  Files           8       11       +3     
  Lines         485      575      +90     
==========================================
+ Hits          424      513      +89     
- Misses         61       62       +1     

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