test: cover follow-up route boundaries

[cursor]

Summary

• Add deterministic route-level coverage for POST /api/sessions/[id]/followup.
• Add test-only aliases and a lightweight NextResponse stub so the root Vitest suite can exercise the real handler without requiring the Next.js runtime.
• Keep production behavior unchanged.

Risky behavior now covered

• Malformed JSON and blank messages are rejected before session lookup or vendor calls.
• Missing or tenant-inaccessible sessions return 404 without constructing an adapter.
• Valid follow-ups use the persisted session vendor and exact session ID/message, with exactly one paid vendor invocation.
• Vendor failures return 502 rather than a false success.

Test files added/updated

• test/followup-route.test.ts
• test/support/next-server.ts
• vitest.config.ts

Regression-risk reduction

The follow-up endpoint is a core authenticated workflow that can trigger paid external vendor work. These tests protect the validation and tenant-scoped lookup boundaries and catch wrong-vendor, altered-message, duplicate-dispatch, and false-success regressions without fragile network or browser dependencies.

Validation

• npm test — 43/43 tests pass.
• npm run build — passes.
• npx prettier --check vitest.config.ts test/followup-route.test.ts test/support/next-server.ts — passes.
• Mutation checks confirmed the suite fails for a hard-coded wrong vendor and for duplicate vendor dispatches.

  

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Project	Deployment	Actions	Updated (UTC)
polyagent	Ready	Preview, Comment	Jul 28, 2026 10:10am

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[parvezk]

@cursoragent this is part of which Cursor thread, or is there a Linear issue to track this? I don't remember where this issue fix request originated?

[cursor]

This came from a Cursor automation, not a Linear issue.

• Cursor thread/run: https://cursor.com/agents/bc-c43e147c-0ebe-4a50-878f-0dbf6c6640f0
• Automation: “Add test coverage” — https://cursor.com/automations/e3967ddd-7f97-11f1-ba66-0e7d0216e441
• Branch/PR: cursor/missing-test-coverage-f4ef, PR test: cover follow-up route boundaries #75
• Linear: no associated Linear issue found; the run metadata has linearIssueId: null.

The origin appears to be the recurring “test coverage automation” looking for risky untested paths. It also posted to Slack #polyagent here: https://pk-sfs3859.slack.com/archives/C0BGTS8KHE3/p1785233455266339