[Integration DoD][MW-09] Define integration observability contract and enforce it

[github-actions]

This issue is auto-generated from INTEGRATION_DOD_MAP.md by the nightly DoD gap sync workflow.

Gap

• ID: MW-09
• Owner (area-owner): DX/Tooling

Acceptance Criteria

• Minimal metric fields (success/failure/latency) are defined and tested for major boundaries.

Verification Commands

bun run typecheck
bunx vitest run <observability-tests>

Risk

• Slow incident triage and no measurable reliability baseline.

Source

• INTEGRATION_DOD_MAP.md:465

[hellopleasures]

Addressed in PR #771.

Gaps found:

1. Tautological boundary coverage test — BOUNDARIES and expected were identical hand-written arrays; test could never fail even if IntegrationBoundary was extended. Fixed by parsing the type union from the source file.
2. Semi-tautological metric fields test — constructed an object then asserted on its own properties. Replaced with two tests that validate real span output (success + failure paths).

Net: 51 → 52 tests (1 tautological → 2 real validations).