[yangshun]

React, Vue, Svelte, and Solid each duplicated island-form JSON submission and response handling. Extract submitIslandAction into the existing void/pages-client entry and reuse it across all four adapters, including the existing action-error decoder.

These HTTP submission and response rules are unlikely to differ across frameworks; sharing them ensures fixes apply consistently to every adapter.

The adapters retain their state updates, success timers, navigation, reloads, and Promise-based submission APIs. This removes 98 net production lines and adds 47 regression cases covering redirect precedence, validation, HTTP error classification, body decoding, usage-limit metadata, and request failures.

Validation:

• vp run --no-cache test:all --maxWorkers=4 passed: formatting, lint, package/playground builds, build-artifact checks, workspace typechecking, and 15,073 tests (31 skipped).
• Island-form browser contract passed for all four adapters: 8 cases.
• The separate packed-consumer full matrix remained incomplete after initializer timeouts in the npm React and Vue cases.

[cpojer]

Thank you!