[howlcipher]

M3 task 3: closures and event dispatch (plan: "Handlers").

• A lambda (the last argument of on_event, on_media, on_visible, on_scroll or spawn) is lifted to a function (env, a0, a1); a closure is a $Closure (function reference and an environment of $Cells). Variables any lambda in a function names live in cells made afresh at each binding, so handlers share variables with the code around them, as JavaScript closures do, and a handler made in a loop keeps its iteration's variable. Every binding site of the compiler goes through one binding abstraction now.
• The host calls a closure with __hf_invoke; the loader wraps it as a JavaScript function returning a promise, like the JavaScript backend's async handlers: a handler's uncaught error or exit rejects that promise alone.
• on_event now calls one shared runtime function in both backends (howlFrameOnEvent); the subscriptions use the JavaScript backend's runtime; the table gives a lambda's parameters kinds (event, element, bool) that the loader converts by.
• spawn is a browser import that runs the closure at once (no capability: a task, not a process).
• A lambda of more than two parameters, and spawn outside the browser, fail closed.

Test Impact Assessment

• Behavior changed: on_event, the subscriptions and spawn build for the browser; the JavaScript backend's on_event emits howlFrameOnEvent(...) (same effect).
• Tests that prove it: TestBrowserHandlersLikeJavaScript (12 programs on both backends; the stand-in page clicks every listened element, scrolls, flips a media query, makes an element visible and records rejections and unhandled rejections: shared and per-iteration captures, captured lists and dicts, nested handlers, handlers made in a function, handler errors and exits, a missing element, spawn, subscriptions and off), TestBrowserFailsClosed updated; the existing JavaScript browser tests (on_event, subscriptions) pass unchanged; the differential corpus passes after the binding refactor.
• Gaps: asynchronous handlers (next PR).
• Tests actually run: HOWLSCENE_HF=… scripts/wasmgc_gate.sh on the tree before merging main (d9b884e6); merging main changed no file.
• Gate summary: tools go1.26.0, node v22.22.1, wasmtime 47.0.3, wasm-tools 1.254.0; HowlScene HF 247365e. Go 1.26: 4355 passed, 31 skipped by design; Go 1.27.2: 4353 passed, 33 skipped by design; HowlScene HF gates: 6 passed. wasmgc gate: passed.

🤖 Generated with Claude Code

https://claude.ai/code/session_01AcSTmyDDtEcBifmcTbNcRW

[howlcipher]

The merge went through as bd868833 ("Merge pull request #291 from howlcipher/feat/wasmgc-handlers" is main's head; this branch is 0 commits ahead of main), but the merge request returned a 502 and GitHub did not record the pull request as merged. Nothing of this branch is missing from main.

🤖 Generated with Claude Code