Observability Coverage Audit

Observability Coverage Audit

Find which code paths, error states, or failure modes are exercised by tests, monitors, alerts, or runbooks — and which are silent. The output is a per-site coverage matrix with gap rows for the uncovered sites.

Required Loading

Always load:

• prompts/coverage-audit.md — the per-site coverage framework; the per-control matrix.

When To Run

• After an incident, before closing the postmortem: "could this have been detected earlier?".
• Before launching a new code path: "is this path observable end to end?".
• Quarterly as part of the resilience-engineering review.
• When a SLO breach keeps recurring despite the obvious fix: "is the test that 'fixes' it actually testing the production path?".

Discovery Order

1. Identify the in-scope code path or failure class. Examples: the payments.charge path; every throw in the service; every external HTTP call.
2. For each site, find the existing coverage: test files (*_test.go, *.spec.ts, etc.), alert rules (in the metrics backend), runbook entries (in the runbook repo), dashboards.
3. For each site, ask: does the existing coverage actually exercise the production path? A test that mocks the dependency is not coverage of the dependency.
4. For each gap, classify: missing test, missing alert, missing runbook, missing all three. The classification is the suggested fix.

Output Contract

The coverage matrix is grouped by site. For each site, name:

• the site (path + line)
• the test coverage (existing test name, or MISSING)
• the alert coverage (existing alert name, or MISSING)
• the runbook coverage (existing runbook path, or MISSING)
• the suggested fix (which coverage to add)

A site missing all three is a COV-SILENT finding. A site missing only the runbook is a COV-NO-RUNBOOK finding. The classification is the suggested-fix priority.

Tools

• codegraph_explore — one-shot fanout when the in-scope path is a feature.
• codegraph_search — locate the error / exception / throw site by name.
• codegraph_callers — every site that can hit the error.
• codegraph_files — test file filter.
• Fallback — per-feature source inspection + manual test/alert/runbook search.

Fallback

If CodeGraph is unavailable, the fallback is per-feature source inspection. The final report must include the line:

CodeGraph unavailable; coverage gathered by rg/file inspection.

Related Skills

• spec-doc-linter — keeps DevAgent.md / CONTEXT.md honest.
• incident-call-trace — walks the failing path during an incident; this skill is the post-incident 'could this have been detected?' audit.
• data-lineage-trace — the upstream input: a coverage gap without a data-lineage report is missing the sink list.
• goal-driven-development — orchestrates the spec-to-code flow; this skill is the post-incident / pre-launch counterpart.

Examples

Each bad-* doc has a matching good-* in examples/ showing the minimum matrix. Read them side by side to calibrate depth. examples/coverage-output.md is the canonical "what the agent should emit" sample.