fix(tracing): Adjust trace-artifact granularity and grouping in @wdio/devtools-service

[Winify]

What & why

Three tracing fixes/features for @wdio/devtools-service:

Bug fix — lastSelector bleed-through across tests. Element-scoped commands (click, setValue, etc.) in test B could silently inherit the selector from test A's last $() / findElement call. Fixed by resetting the selector cache in beforeTest() via SessionCapturer.resetLastSelector().

Feature — traceGranularity: 'spec'. Each spec file now produces its own trace artifact (zip or ndjson-directory) instead of one monolithic trace per worker session. Enabled via traceGranularity: 'spec' in the service options. Default remains 'session'.

Feature — it() / Scenario() grouping in traces. When test hooks are available, each test becomes a Tracing.tracingGroup span in the trace NDJSON. Child actions carry parentId pointing to the group so timeline viewers render tests as labelled spans wrapping their commands.

// wdio.conf.js
services: [['devtools', {
    mode: 'trace',
    traceFormat: 'zip',
    traceGranularity: 'spec'     // one trace per spec file
}]]

How

• testUid (deterministic hash of specFile + testTitle) is tagged on every captured command via SessionCapturer.afterCommand().
• buildActionEvents() in core/trace-exporter.ts detects testUid changes in the command stream and emits tracingGroup open/close pairs.
• beforeTest() tracks spec-file boundaries via index ranges (SpecRange). #flushSpecTrace() slices the accumulated arrays and writes a standalone trace artifact per spec. Mid-run flushes are fire-and-forget with .catch() error logging.
• Spec-scoped test metadata is derived from a single #testMetadata map filtered by specFile — no dual-source-of-truth risk.
• Trace filenames include an 8-char base36 hash of the full spec path, so two specs with the same basename in different directories don't collide.

Type of change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Polish (an improvement to an existing feature)
• Breaking change (existing behavior changes for users)
• Documentation
• Internal (build, CI, dependencies, tooling)

Packages touched

• shared (types and contracts)
• core (framework-agnostic capture/reporting)
• service (WebdriverIO adapter)
• nightwatch-devtools (Nightwatch adapter)
• selenium-devtools (Selenium adapter)
• backend (server)
• app (UI)
• script (page-injected runtime)

Notes for reviewers

Screenshots / recordings