feat(telemetry): instrument startup

[EhabY]

Summary

• Trace activation startup with authState, duration, and result; activation no longer emits granular phase properties.
• Trace fire-and-forget stored deployment initialization separately as activation.deployment_init.
• Trace remote.setup with hierarchical child phases: auth_retrieval, workspace_lookup, workspace_ready, agent_ready, and ssh_config_write.
• Trace CLI binary download and signature verification attempts, including download reason and downloadedBytes once response body bytes are written.
• Add span-owned property/measurement mutators so telemetry can record values discovered during traced work without mutating caller-owned objects.

Notes

• Uses the current telemetry span model, so remote phases emit as hierarchical event names like remote.setup.workspace_lookup rather than remote.setup.phase with a phase property.
• RemoteSetupTelemetry exposes a single typed phase(...) helper instead of one method per phase.
• cli.download.reason currently supports missing and version_mismatch; there is no true forced-download path in the current CLI manager flow.
• cli.download.measurements.downloadedBytes is emitted when bytes are written, including failed downloads that wrote a partial body; it is omitted when the server returns HTTP 304 because no response body bytes are written.

Tests

• pnpm lint
• pnpm typecheck
• pnpm test:extension ./test/unit/core/cliManager.test.ts
• pnpm test:extension ./test/unit/core/cliManager.concurrent.test.ts
• pnpm test:extension ./test/unit/telemetry/service.test.ts
• pnpm format:check

Closes #904.

Implementation plan and decisions

Decisions

1. Remote setup phases follow the current telemetry architecture: hierarchical phase event names such as remote.setup.workspace_lookup, not remote.setup.phase with a phase property.
2. Activation telemetry preserves existing behavior. Stored deployment initialization remains fire-and-forget and is instrumented separately as activation.deployment_init.
3. Activation phases were removed from the implementation; the activation event records bounded authState, durationMs, and result.
4. CLI download byte telemetry records downloadedBytes as bytes are written from an HTTP 200 response, so partial failed downloads retain the last written byte count. HTTP 304 emits cli.download but omits the byte measurement.
5. cli.download reasons use what the current code can determine. Current code supports missing and version_mismatch; there is no true forced download path today.
6. ServiceContainer is still constructed before initVscodeProposed; construction does not call proposed APIs, and proposed API usage remains after initialization.

Implementation

• Wire TelemetryService into CliManager through ServiceContainer.
• Add Span.setProperty and Span.setMeasurement, with TelemetryService copying caller-owned objects at span start.
• Split startup instrumentation helpers into activation and remote setup modules.
• Instrument activation with TelemetryService.trace("activation", ...), using bounded authState values.
• Preserve fire-and-forget deployment initialization and attach telemetry via the existing promise chain.
• Instrument Remote.setup() with TelemetryService.trace("remote.setup", ...) and child phases.
• Keep phase wrapping at the orchestration level in remote.ts while calling helper methods without telemetry where possible.
• Instrument actual CLI download attempts with cli.download.
• Instrument signature verification attempts with cli.verify.
• Add targeted unit tests around span mutation isolation, CLI download measurements, partial download error telemetry, and CLI telemetry behavior.

Generated by Coder Agents.

[EhabY]

/coder-agents-review