[2ynn]

Why

Two config fields declare their gen.yaml checks as a ValidationFunc on the field definition in config.ts:

• typescriptv2 usageSDKInitImports: must be an array of objects with a non-empty package and import, and an optional type of typeImport, packageImport, or aliasImport.
• mcp-typescript advancedFlags: must be an array of alphanumeric strings.

Nothing reads ValidationFunc. GetLanguageConfigFields decodes the field definitions into sdk-gen-config's SDKGenConfigField, which has no such field, so the key is dropped and neither check has ever run. Malformed values are accepted silently: a usageSDKInitImports entry without import passes an undefined import name to addUsageImport, and an advancedFlags entry such as dry-run can never match a flag name, because gatherMCPFlags compares entries against sanitizeFieldName(flag.Name).

What changed

• templates/templates/typescriptv2/config.ts, templates/templates/mcp-typescript/config.ts: each check moves into a target-level validateConfig(cfg). This is the hook Generator.validateConfig (pkg/generate/configuration.go) already runs on gen.yaml for the cli, go, javav2, php, pythonv2, and ruby targets; a non-empty message fails generation with gen.yaml validation error for <target>: <message>. The ValidationFunc keys are removed.
• The usageSDKInitImports check resolves package || Package, import || Import, and type || Type before validating, matching templateUsageSDKInit, so entries using the capitalized keys keep generating.
• Absent and null values are skipped. Templating already treats both as empty (templateUsageSDKInit checks Array.isArray, gatherMCPFlags checks truthiness), and an empty usageSDKInitImports: or advancedFlags: key in gen.yaml decodes to null, which the old function would have rejected.
• pkg/generate/typescript_config_validation_test.go: error and success cases for both fields, including capitalized and mixed-case import keys, every import type, empty and non-string values, and empty flag names, through Generator.validateConfig, in the same style as cli_config_validation_test.go. That file's newCLITestConfig helper becomes newLanguageTestConfig(target, cfg) so both test files share it.
• Changeset: core / typescriptv2, mcp-typescript patch.

Behaviour change: a gen.yaml with a malformed value for either field now fails validation instead of generating. Import types other than typeImport, packageImport, or aliasImport now fail validation. Previously, unrecognized values silently rendered as typeImport. Generated output for valid configurations does not change, so no review SDKs are regenerated; the existing review and test configurations (advancedFlags: [loneQueryParam], usageSDKInitImports: []) pass.

Testing

• go test ./pkg/generate -run TestValidateConfigTypeScript -count=1: passes. With the template changes reverted, all 15 error cases fail.
• go test ./pkg/generate -count=1: passes.
• cmd/generate against a one-operation spec, with gen.yaml leaving templateVersion unset:
  • typescript with usageSDKInitImports: [{package: "@acme/sdk"}] fails with gen.yaml validation error for typescript: usageSDKInitImports[0].import must be a non-empty string; adding import: Acme generates.
  • mcp-typescript with advancedFlags: [dry-run] fails with gen.yaml validation error for mcp-typescript: advancedFlags[0] must contain only letters or numbers; dryRun generates.
• make check-template-typescriptv2, make check-template-mcp-typescript, make lint: pass.

Public-safety check

• This change contains no credentials, customer documents, private repository URLs, private filesystem paths, or unredacted private logs.
• Title, body, comments, and commit messages name no customers or customer-derived identifiers, private paths or trackers, or workflow provenance, and are understandable without private context (.claude/skills/public-repo-communication/SKILL.md).
• Generated fixtures and review SDK changes are public-safe.
• I reviewed git diff --check.

[cubic-dev-ai]

All reported issues were addressed across 5 files

<sub>Shadow auto-approve: would not auto-approve because issues were found.

View guided diff | Turn on auto-fix | Re-trigger cubic</sub>

[cubic-dev-ai]

0 issues found across 2 files (changes from recent commits).

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

<sub>Shadow auto-approve: would auto-approve. Moves dead per-field config validators into the target validateConfig hook so malformed usageSDKInitImports/advancedFlags now fail generation; tests and patch changeset included, valid output unchanged.

View guided diff | Turn on auto-fix | Re-trigger cubic</sub>

[speakeasy-generator-bot]

Generator Snapshot Testing

Selector(s)	Result	Summary
snapshot-mcp-typescript, snapshot-typescript	❌	Snapshot run failed

Snapshot results: https://github.com/speakeasy-api/openapi-generation-snapshots/issues/140#issuecomment-6427958477

Snapshot results are summarized above. Additional run context is linked for maintainers with access.

[TristanSpeakEasy]

Looks good, moving these checks into validateConfig makes sense. Keeping the capitalised import keys and null values working avoids unnecessary breakage.