fix(server): serve /version on Lambda (excluded from static-path fallback)

[cristim]

Root cause

isStaticPath() in internal/server/static.go only excluded /api/* and
/health from the SPA file-server fallback. /version was not in the
allowlist, so on the Lambda Function URL path (handleLambdaHTTPEvent) the
check isStaticPath("/version") == true caused the request to be routed to
serveLambdaStatic, which served index.html instead of JSON.

The HTTP / Cloud Run / Fargate path (CreateHTTPServer in
internal/server/http.go) was unaffected because mux.HandleFunc("/version", app.handleVersion) is registered explicitly before the SPA catch-all handler,
so the Go ServeMux routes it correctly regardless of isStaticPath.

The /version route has been in the API router table since PR #901
(ExactPath: "/version", Auth: AuthPublic). Once isStaticPath("/version")
returns false, app.API.HandleRequest handles it correctly on the Lambda path
too.

Verified live before the fix:

curl https://33pz7pombdqwu3bdlxp4lqxyra0bsriy.lambda-url.us-east-1.on.aws/version
# returned text/html (index.html)

Fix

Add clean == "/version" to the isStaticPath allowlist using the same
pattern as /health. Updated the function doc comment to mention /version as
a public root-path endpoint and explain why it must bypass the SPA fallback.

Tests

Added two cases to TestIsStaticPath in internal/server/static_test.go:

• {"/version", false} - direct path
• {"//version", false} - double-slash input normalised by path.Clean

All 334 tests in ./internal/server/... pass. gofmt and go vet clean.

Notes

No issue to close - discovered during deploy debugging of the #901 build-version
diagnostic endpoint on a Lambda Function URL deployment. Behaviour is now
consistent across all deployment targets (Lambda, Cloud Run, Fargate).

Summary by CodeRabbit

• Bug Fixes
  • Corrected routing logic to ensure the /version endpoint is properly directed to the API handler instead of incorrectly falling through to static content serving.

[cristim]

@coderabbitai review

[coderabbitai]

📝 Walkthrough

Walkthrough

The PR updates static-path routing logic to explicitly treat /version as an API endpoint that must not fall through to the SPA static/Lambda fallback. Documentation is clarified, the isStaticPath function adds an explicit check for /version, and tests are updated to verify the endpoint is non-static.

Changes

Version Endpoint Routing

Layer / File(s)	Summary
Exclude /version from static path handling internal/server/static.go, internal/server/static_test.go	Documentation in isStaticPath clarifies that /version is a public root-path endpoint handled by the API router and must not fall through to SPA/Lambda fallback. Logic adds an explicit clean == "/version" check to exclude it from static handling. Tests assert /version and //version are non-static paths.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Possibly related PRs

• LeanerCloud/CUDly#901: Complements this routing exclusion by adding the actual /version handler and public auth allowlisting for it.

Suggested labels

priority/p2

Poem

🐰 A /version that wandered too far,
Down static paths beneath the stars,
Now rooted firm in API's keep,
No SPA fallback, promises to keep!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: fixing the /version endpoint routing to exclude it from the static-path fallback on Lambda, which matches the core fix in the changeset.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/version-endpoint-lambda-static-shadow

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Review triggered.

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🧹 Nitpick comments (1)

internal/server/static_test.go (1)

97-98: 💤 Low value

Consider adding a trailing-slash test case for completeness.

The test cases correctly verify that /version and //version are non-static. For more comprehensive coverage, consider adding {"/version/", false} to confirm that path.Clean("/version/") → "/version" also bypasses the SPA fallback.

📋 Optional test case addition

 		{"/version", false},  // public build-metadata endpoint must reach API, not SPA
 		{"//version", false}, // double-slash normalised to /version
+		{"/version/", false}, // trailing slash normalised to /version
 	}

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@internal/server/static_test.go` around lines 97 - 98, Add a trailing-slash
case to the static handler tests: update the test cases slice in
internal/server/static_test.go (the table that currently contains {"/version",
false} and {"//version", false}) to include {"/version/", false} so the test
verifies path.Clean("/version/") → "/version" still bypasses the SPA fallback;
ensure the new entry uses the same expected boolean and test logic as the other
non-static cases.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@internal/server/static_test.go`:
- Around line 97-98: Add a trailing-slash case to the static handler tests:
update the test cases slice in internal/server/static_test.go (the table that
currently contains {"/version", false} and {"//version", false}) to include
{"/version/", false} so the test verifies path.Clean("/version/") → "/version"
still bypasses the SPA fallback; ensure the new entry uses the same expected
boolean and test logic as the other non-static cases.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: e1763440-febb-478d-b1e1-bc2254ddd7e2

📥 Commits

Reviewing files that changed from the base of the PR and between 80c20d2 and 647b111.

📒 Files selected for processing (2)

• internal/server/static.go
• internal/server/static_test.go