Fix package .js.flow type discovery

[landeqiming666]

Summary

• Prefer .js.flow files over stripped JavaScript siblings when discovering Flow definition files.
• Register package-root node_modules/<package>/index.js.flow exports as an implicit module when the file does not already declare one.
• Add an end-to-end CLI regression for a package that ships index.js plus index.js.flow.

Why

Fixes #27. Flow resolves index.js.flow before index.js for packages that ship copied Flow sources, but the flow-runtime definition output path did not model that package entrypoint. This meant imported package types could be missing even though Flow itself could see them.

This differs from #288, which only discovers .js.flow files and tests an already explicit declare module fixture. The new regression creates a temporary package with stripped JS plus typed .js.flow, then verifies import type {ExternalUser} from "fixture-package" emits a t.module("fixture-package", ...) definition. It also differs from #297, which focuses on module.name_mapper.extension remapping rather than package .js.flow entrypoint resolution.

Validation

• GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=url.https://github.com/.insteadOf GIT_CONFIG_VALUE_0=git://github.com/ npx yarn@1 install --frozen-lockfile --ignore-engines --ignore-scripts
• npx yarn@1 workspace flow-runtime build-cjs
• npx yarn@1 workspace flow-config-parser build
• npx yarn@1 workspace babel-plugin-flow-runtime build
• npx yarn@1 workspace flow-runtime-cli test -- src/__tests__/jsFlowPackageDefinitions.test.js
• npx yarn@1 workspace flow-runtime-cli test -- src/__tests__/generateDefinitions.test.js
• npx yarn@1 workspace flow-runtime-cli test
• npx yarn@1 workspace flow-runtime-cli build
• git diff --check

Note: a full install without --ignore-scripts is blocked locally by the old node-sass / node-gyp@3.8.0 toolchain requiring python / python2 on Node v25.8.1. The package-level CLI tests and build above pass after building the required workspaces.

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IssueHunt Summary

Referenced issues

This pull request has been submitted to:

• #27: Types not resolving to .js.flow files

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[landeqiming666]

Hi, a brief follow-up on this PR. It remains clean and mergeable. The focused tests cover package-root node_modules//index.js.flow discovery and implicit module registration. Happy to adjust the resolution behavior or fixtures.