feat(express): derive api.<bare-domain> for OpenAPI servers.url

[PierreBrisorgueil]

Summary

• Extracts computeOpenApiServerUrl(domain) as a named pure export from lib/services/express.js
• When config.domain is a bare host (e.g. trawl.me), the OpenAPI servers.url now correctly resolves to https://api.trawl.me instead of the frontend hostname verbatim
• Backward-compatible: full-URL domains (http://... or https://...) are returned unchanged
• 5 unit tests covering: bare host, https URL, http URL, custom-subdomain URL, falsy fallback

Why

Every devkit downstream with a split frontend/backend topology (<bare> → api.<bare>) was advertising the wrong API host in its OpenAPI spec. Trawl's production-validated pattern prepends https://api. when no scheme is present.

Promote-up from trawl_node (production-validated). Closes #3766.

Part of infra plan 2026-06-01-trawl-promote-up-followups.md, Task 1.

Phase 0 gate (pre-push critical-review via DeepSeek)

Verdict: OK with nits — 0 critical, 0 high. Medium: bare host:port edge case (e.g. localhost:3000 → https://api.localhost:3000) acknowledged — config.domain in practice is always a bare hostname or full URL; the fallback default covers the localhost case. Low: intentional behavioral change for bare-hostname downstreams (correct and expected). No blocking findings.

Test plan

• NODE_ENV=test npm run test:unit -- lib/services/tests/express.openapi-servers → 5 tests pass
• npm run lint → clean
• NODE_ENV=test npm run test:coverage -- --testPathPatterns='unit' → 1680 tests pass, coverage thresholds met
• Runtime: server started with DEVKIT_NODE_domain=trawl.me → GET /api/spec.json returns "servers":[{"url":"https://api.trawl.me"}] ✅

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ℹ️ Review info

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Run ID: 29924152-6eb7-4f1b-ac8b-366759dedbd4

📥 Commits

Reviewing files that changed from the base of the PR and between 5604011 and 9c65788.

📒 Files selected for processing (2)

• lib/services/express.js
• lib/services/tests/express.openapi-servers.unit.tests.js

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/promote-api-domain-prefix

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[Copilot]

Pull request overview

Extracts a small pure helper computeOpenApiServerUrl(domain) from lib/services/express.js so that when config.domain is a bare host (e.g. trawl.me), the OpenAPI servers.url resolves to https://api.<domain> instead of advertising the frontend hostname. Full-URL domains (http(s)://...) are preserved verbatim, keeping behavior backward-compatible.

Changes:

• Add exported computeOpenApiServerUrl and use it in initSwagger for spec.servers.
• Add 5 unit tests covering bare host, http/https URLs, custom subdomain, and falsy fallback.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
lib/services/express.js	Adds computeOpenApiServerUrl helper and uses it to derive spec.servers[0].url.
lib/services/tests/express.openapi-servers.unit.tests.js	New unit tests covering scheme-preserving and api. prepending behaviors.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.15%. Comparing base (7ed5291) to head (9c65788).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #3770       +/-   ##
===========================================
+ Coverage   59.43%   90.15%   +30.71%     
===========================================
  Files         151      151               
  Lines        4970     4977        +7     
  Branches     1577     1578        +1     
===========================================
+ Hits         2954     4487     +1533     
+ Misses       1491      385     -1106     
+ Partials      525      105      -420     

Flag	Coverage Δ
integration	59.51% <100.00%> (+0.07%)	⬆️
unit	69.07% <100.00%> (?)

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