feat: add workflow telemetry traces

[EhabY]

Generated by Coder Agents.

Fixes #986.

Summary

• add privacy-safe workflow traces for workspace picker/open/devcontainer handoffs, start prompts, and diagnostic command completions
• preserve existing command.invoked coverage while marking normally-returned cancellation/failure paths with bounded categories
• avoid logging raw workspace names, picker queries, local/export/devcontainer paths, or raw command output
• return structured telemetry export outcomes so caller telemetry can distinguish success, cancellation, and failure

Validation

• pnpm test:extension ./test/unit/instrumentation/commands.test.ts ./test/unit/instrumentation/workspace.test.ts ./test/unit/telemetry/export/command.test.ts ./test/unit/uri/uriHandler.test.ts
• pnpm format:check
• pnpm lint
• pnpm typecheck
• git diff --check

Implementation plan

Issue 986 telemetry implementation plan

Goal

Add the missing low-volume, privacy-safe telemetry for issue #986 without duplicating existing command.invoked, workspace state transition, or start/update operation telemetry.

Principles

• Keep command.invoked as the broad command coverage signal.
• Add specific traces only where command handlers return normally on cancellation/failure or where command-specific context is otherwise invisible.
• Use existing result semantics from TelemetryService.trace:
  • result=success for completed/accepted/selected paths.
  • result=aborted for user cancellation/dismissal.
  • result=error for thrown or handled failures, using span.markFailure() when the command handles the error and returns.
• Avoid raw workspace names, search queries, local/export/devcontainer paths, and raw command output.
• Match existing dot-separated telemetry naming patterns such as command.invoked, workspace.update.prompted, and workspace.start.triggered.

Event plan

Existing event retained

• command.invoked
  • No schema expansion planned.
  • Still records command ID, duration, thrown errors, and top-level command success/error.

Workspace picker

• workspace.picker.prompted
  • One trace per picker opening.
  • Properties: picker source/category where useful, selected workspace state bucket when selected.
  • Measurements: final result count and selected workspace agent counts.
  • Result: success when a workspace is selected, aborted when dismissed, error when fetching/searching fails.

Workspace open handoff

• workspace.open
  • One trace covering open and openFromSidebar handoff to VS Code.
  • Properties: source, workspace/build/agent state buckets, handoff category.
  • Measurements: agent counts.
  • Result: success when VS Code open handoff succeeds, aborted when the user cancels workspace/agent/recent-folder selection, error when the handoff fails.

Devcontainer open handoff

• workspace.devcontainer.open
  • One trace around devcontainer handoff.
  • Properties: mode/category and bounded failure category on handled/known errors.
  • Result: success or error.

Start/update prompt decisions

• workspace.start.prompted

  • For the stopped-workspace modal that asks whether to start/update.
  • Properties: whether an update was offered and the accepted action when present.
  • Result: success when a choice is accepted, aborted when dismissed.

• workspace.update.prompted

  • Reuse the existing event name.
  • Add a compact prompt-kind/action property where practical so parameter prompting and confirmation prompting remain distinguishable without adding another update event.

Diagnostic command outcomes

• command.diagnostic.completed
  • One event name for coder.speedTest, coder.supportBundle, and coder.exportTelemetry.
  • Property: commandId plus bounded outcome/failure category where useful.
  • Measurements: bounded summaries only, e.g. requested speedtest seconds, parsed interval count/throughput, exported event count. No paths or raw output.
  • Result: success, aborted, or error using span.markAborted() / span.markFailure() for handled outcomes.

Test plan

• Update test/unit/instrumentation/workspace.test.ts for prompt telemetry behavior.
• Update test/unit/telemetry/export/command.test.ts for export diagnostic outcomes.
• Add focused command tests only where the behavior cannot be validated through smaller exported helpers.
• Run targeted unit tests first, then pnpm typecheck or targeted typechecking if needed.