feat(router): add allow_string_literals_for_enums engine option

[devsergiy]

Summary by CodeRabbit

• New Features

  • Added an opt-in router setting to accept matching string literals for enum arguments and input fields.
  • Non-matching strings and invalid scalar values continue to be rejected.
  • Existing GraphQL enum literal behavior remains unchanged.

• Documentation

  • Added configuration guidance, examples, defaults, and environment-variable documentation for the new setting.
  • Added the new page to the Router documentation navigation.

Checklist

• I have discussed my proposed changes in an issue and have received approval to proceed.
• I have followed the coding standards of the project.
• Tests or benchmarks have been added or updated.
• If applicable, I have provided instructions for reviewers for manually validating my changes.
• Documentation has been updated on https://github.com/wundergraph/docs-website.
• I have read the Contributors Guide.

Open Source AI Manifesto

This project follows the principles of the Open Source AI Manifesto. Please ensure your contribution aligns with its principles.

[mintlify]

Preview deployment for your docs. Learn more about Mintlify Previews.

Project	Status	Preview	Updated (UTC)
wundergraphinc	🟢 Ready	View Preview	Jul 21, 2026, 9:11 PM

💡 Tip: Enable Workflows to automatically generate PRs for you.

[github-actions]

Router-nonroot image scan passed

✅ No security vulnerabilities found in image:

ghcr.io/wundergraph/cosmo/router:sha-5a9e8d2f2f366106baebab4d9b174fbc3eb11362-nonroot

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: d46dfce6-2516-49b6-a419-1248a308eb88

📥 Commits

Reviewing files that changed from the base of the PR and between 3fb8819 and e06eac2.

📒 Files selected for processing (10)

• docs-website/docs.json
• docs-website/router/configuration.mdx
• docs-website/router/string-literals-for-enums.mdx
• router-tests/operations/inline_literal_validation_test.go
• router/core/graph_server.go
• router/core/operation_processor.go
• router/pkg/config/config.go
• router/pkg/config/config.schema.json
• router/pkg/config/testdata/config_defaults.json
• router/pkg/config/testdata/config_full.json

🚧 Files skipped from review as they are similar to previous changes (10)

• router/pkg/config/testdata/config_defaults.json
• docs-website/router/string-literals-for-enums.mdx
• docs-website/docs.json
• router/pkg/config/testdata/config_full.json
• router/pkg/config/config.go
• router/pkg/config/config.schema.json
• router/core/graph_server.go
• docs-website/router/configuration.mdx
• router/core/operation_processor.go
• router-tests/operations/inline_literal_validation_test.go

---

Walkthrough

Adds an opt-in router configuration that allows matching string literals for GraphQL enum values, propagates it through validation, tests enabled and disabled behavior, and documents the option.

Changes

Enum string literal support

Layer / File(s)	Summary
Configuration contract and documentation router/pkg/config/config.go, router/pkg/config/config.schema.json, router/pkg/config/testdata/*, docs-website/router/configuration.mdx, docs-website/docs.json, docs-website/router/string-literals-for-enums.mdx	Adds the allow_string_literals_for_enums configuration field, defaults, schema metadata, navigation entry, and usage documentation.
Validation option propagation router/core/graph_server.go, router/core/operation_processor.go	Passes the configuration through operation processor construction and conditionally enables enum string-literal validation.
Enum literal behavior coverage router-tests/operations/inline_literal_validation_test.go	Tests default rejection, enabled acceptance of matching enum strings, rejection of non-matching strings, and unchanged scalar and enum literal validation.

Estimated code review effort: 3 (Moderate) | ~20 minutes

🚥 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 clearly matches the main change: adding the allow_string_literals_for_enums router engine option.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.12.2)

level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain main module or its selected dependencies"

---

_{Comment @coderabbitai help to get the list of available commands.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.06%. Comparing base (cfee827) to head (e06eac2).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3103      +/-   ##
==========================================
+ Coverage   61.83%   62.06%   +0.23%     
==========================================
  Files         262      262              
  Lines       30810    30814       +4     
==========================================
+ Hits        19050    19124      +74     
+ Misses      10233    10178      -55     
+ Partials     1527     1512      -15     

Files with missing lines	Coverage Δ
router/core/graph_server.go	85.53% <100.00%> (+0.41%)	⬆️
router/core/operation_processor.go	86.74% <100.00%> (+0.04%)	⬆️
router/pkg/config/config.go	83.00% <ø> (ø)

... and 14 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.