Feat/msw plugin restore - #4114

✅ No new issues found.

Reviewed changes — restores the MSW plugin, generating type-safe mock handler factories from OpenAPI specs with support for static values, custom resolver functions, path parameter handling, route specificity sorting, and configurable fallback behavior.

• Add @hey-api/msw plugin — new code generation plugin in packages/openapi-ts/src/plugins/msw/ that emits msw.gen.ts with a createMswHandlers() factory, per-operation handler functions, and supporting types (ToResponseUnion, RequestHandlerOptions, MswHandlerFactories, etc.)
• Add MSW symbols — packages/openapi-ts/src/symbols/msw.ts registers external MSW type references (HttpResponse, HttpHandler, HttpResponseResolver, DefaultBodyType, RequestHandlerOptions, http)
• collectDeps supports array-valued dependencies — packages/shared/src/normalize/value.ts now recursively collects string values from arrays (needed for MSW's source config, which is array-valued)
• Plugin registration — wired up in packages/openapi-ts/src/plugins.ts, config.ts, index.ts, and symbols/index.ts following existing plugin patterns
• Handler sorting by route specificity — sort.ts ensures static routes take precedence over parameterized ones (depth → segment type → declaration order)
• Dominant response computation — computeDominantResponse.ts picks the best 2XX response candidate by media type priority (json > text > binary > void), with example extraction and validation
• Path sanitization — path.ts converts OpenAPI {param} syntax to MSW :param format, escaping existing colons and sanitizing non-word characters in param names
• Test coverage — runtime tests (msw.test.ts), type-level tests (msw-types.test-d.ts), and 60+ snapshot tests across 2.0.x/3.0.x/3.1.x spec versions
• Documentation — new msw.mdx docs page, VitePress config, README update (moved from "proposals" to "available" section)
• @hey-api/examples fix — operation.operationId! → operation.operationId ?? '' to handle nullable operation IDs
• Dependency: [email protected] — added to examples/openapi-ts-fetch for test execution

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ℹ️ Minor suggestion only — one test version mismatch caught.

Reviewed changes — restores the MSW plugin (@hey-api/msw) with a full rewrite following the current plugin architecture. The plugin generates typed MSW v2 handlers from OpenAPI specs, with support for baseUrl configuration, responseFallback (error or passthrough), route specificity sorting, and multiple response format handling.

• Add @hey-api/msw plugin — new plugin config (config.ts), types (types.ts), imports factory (imports.ts), handler dispatch (plugin.ts, v2/plugin.ts), and shared utilities for handler generation, path sanitization, response computation, and route sorting
• Add MSW symbols — symbols/msw.ts registers DefaultBodyType, HttpHandler, HttpResponse, HttpResponseResolver, RequestHandlerOptions, and http from the msw package
• Support array $dependencies in collectDeps — packages/shared/src/normalize/value.ts now walks array-valued dependencies so plugins like MSW that depend on source (which is an array) resolve correctly
• Register plugin — index.ts augments PluginConfigMap, plugins.ts exports msw helper, config.ts registers default config
• Add MSW test project — packages/openapi-ts-tests/msw/v2/ with snapshot tests for 2.0.x, 3.0.x, and 3.1.x specs across multiple scenarios (default, response-example, response-example-disabled, response-types, servers)
• Integrate into openapi-ts-fetch example — add MSW plugin, generate msw.gen.ts, add runtime tests and type-level tests with vitest
• Update @hey-api/examples plugin — guard operation.operationId with ?? '' instead of ! assertion
• Update docs — rewrite msw.mdx documentation page

Note: 1 inline comment(s) dropped because they did not anchor to lines inside the PR diff:

• packages/openapi-ts-tests/msw/v2/test/2.0.x.test.ts:10491 (RIGHT) — line 10491 (RIGHT) is not inside a diff hunk

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