Observability Baseline (Sprint 3 Card #37)

This is an incremental observability foundation for backend_v2 focused on practical CI/local signal quality.

Included Now

• Request correlation IDs (X-Request-ID) echoed on all responses.
• Lightweight in-process counters for request volume, 5xx errors, and latency.
• Summary endpoint for machine-readable health signal:
• GET /api/system/observability/summary
• Synthetic checks for critical paths:
• /health
• /api/system/alpaca/verify
• /api/historical-data/data schema sanity

Run Synthetic Checks

From backend_v2:

python cli.py synthetic-checks --in-process

Against a running backend:

python cli.py synthetic-checks --base-url http://localhost:5001

Strict Alpaca mode (credentials required):

python cli.py synthetic-checks --strict-alpaca

Write CI artifact:

python cli.py synthetic-checks --in-process --output ./artifacts/synthetics-summary.json

Exit Codes

• 0: checks passed (warnings allowed)
• 1: one or more checks failed

Notes

• Non-strict mode treats missing Alpaca credentials as warning to avoid breaking local workflows.
• This baseline is intentionally minimal and does not require Grafana/OTel wiring yet.