test(relay): remove constant-restating database mode test

[t3-code]

problem

infra/relay/src/dbConfig.test.ts repeated the complete implementation of relayDatabaseMode: one assertion for the literal prod branch and two interchangeable strings for the fallback branch. it exercised no relay database construction, stage wiring, or infrastructure boundary, so it could only restate the ternary already visible in production code.

change

• remove the complete dbConfig.test.ts file
• keep the production policy and its reachable caller in infra/relay/src/db.ts unchanged
• retain the relay tests that exercise database behavior and infrastructure boundaries

evidence

• relayDatabaseMode has one production caller, infra/relay/src/db.ts, which uses its result to choose the shared production database or a stage branch
• the removed test called the five-line helper directly and asserted exactly stage === "prod" ? "shared-database" : "stage-branch"
• its two non-production cases (dev_julius and preview) traversed the same unconditional fallback with no state change or distinct branch
• no production behavior, provider, edge case, or integration boundary was removed

verification

• before removal: ./node_modules/.bin/vp test run infra/relay/src/dbConfig.test.ts (1 file, 1 test passed)
• ./node_modules/.bin/vp run --filter t3code-relay typecheck (passed)
• ./node_modules/.bin/vp lint infra/relay/src/dbConfig.ts --report-unused-disable-directives (passed)
• ./node_modules/.bin/vp fmt --check infra/relay/src/dbConfig.ts (passed)
• git diff --check (passed)

model: gpt-5.6-sol
harness: hermes agent

[macroscopeapp]

Approvability

Verdict: Approved at 0c12149

Macroscope's review found this PR approvable — This PR only removes a redundant test from an ignored test path; production relay behavior, configuration, and defaults remain unchanged. The change has no meaningful customer-request runtime impact or applicable sensitive-scope concerns.

Notes:

• No code objects were reviewed. Approvability was decided on eligibility alone.

^{You can add or adjust custom eligibility rules. Learn more.}

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.5 KiB	13.5 KiB	+10 B (+0.1%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	+5 B (+0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.4 KiB	6.4 KiB	+5 B (+0.1%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.2 KiB	56.2 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	9	9	0 (0.0%)	21	✅
Claude	Total thread wire	13.5 KiB	13.5 KiB	−5 B (−0.0%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	−5 B (−0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.4 KiB	6.4 KiB	0 B (0.0%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.0 KiB	57.0 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	9	9	0 (0.0%)	21	✅

Baseline: ab09917 · PR result: 0c12149 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 114.0 KiB
• Claude decoded thread snapshot: 114.7 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.