When the VM or CEK hits an undefined symbol, it checks a symbol→library
index (built from manifest exports at boot), loads the library that
exports it, and returns the value. Execution continues as if the module
was always loaded. No import statements, no load-library! calls, no
Suspense boundaries — just call the function.
This is the same mechanism as IO suspension for data fetching. The
programmer doesn't distinguish between calling a local function and
calling one that needs its module fetched first. The runtime treats
code as just another resource.
Implementation:
- _symbol_resolve_hook in sx_types.ml — called by env_get_id (CEK path)
and vm_global_get (VM path) when a symbol isn't found
- Symbol→library index built from manifest exports in sx-platform.js
- __resolve-symbol native calls __sxLoadLibrary, module loads, symbol
appears in globals, execution resumes
- compile-modules.js extracts export lists into module-manifest.json
- Playground page demonstrates: (freeze-scope) triggers freeze.sxbc
download transparently on first use
2650/2650 tests pass.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- load-library! native: islands can declare module dependencies at
hydration time, triggering on-demand .sxbc loading
- JIT compiler lazy-load: compiler.sxbc loads via setTimeout after boot,
eliminating "JIT: compiler not loaded" errors
- _import_hook on sx_types: infrastructure for hosts to resolve import
suspensions inside eval_expr (server wiring deferred to Step 8)
- Playground page (/sx/(tools.(playground))): REPL island that lazy-loads
the compiler module when navigated to — demonstrates the full
lazy loading pipeline
Known remaining issues:
- SPA navigation broken for pages using let-match (orchestration.sx,
router.sx) — bytecode compiler doesn't handle let-match special form
- Server-side "IO suspension in non-IO context" during http_load_files —
needs cek_run import handling (deferred to Step 8)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Bytecode compiler now emits OP_PERFORM for (import ...) and compiles
(define-library ...) bodies. The VM stores the import request in
globals["__io_request"] and stops the run loop — no exceptions needed.
vm-execute-module returns a suspension dict, vm-resume-module continues.
Browser: sx_browser.ml detects suspension dicts from execute_module and
returns JS {suspended, op, request, resume} objects. The sx-platform.js
while loop handles cascading suspensions via handleImportSuspension.
13 modules load via .sxbc bytecode in 226ms (manifest-driven), both
islands hydrate, all handlers wired. 2650/2650 tests pass including
6 new vm-import-suspension tests.
Also: consolidated sx-platform-2.js → sx-platform.js, fixed
vm-execute-module missing code-from-value call, fixed bootstrap.py
protocol registry transpiler issues.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The transpiled VM (sx_vm_ref.ml, from lib/vm.sx) is now the ACTIVE
bytecode execution engine. sx_server.ml and sx_browser.ml call
Sx_vm_ref.execute_module instead of Sx_vm.execute_module.
Results:
- OCaml tests: 2644 passed, 0 failed
- WASM tests: 32 passed, 0 failed
- Browser: zero errors, zero warnings, islands hydrate
- Server: pages render, JIT compiles, all routes work
The VM logic now lives in ONE place: lib/vm.sx (SX).
OCaml gets it via transpilation (bootstrap_vm.py).
JS/browser gets it via bytecode compilation (compile-modules.js).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The change to re-render children when non-empty caused the stepper's
lake to show raw SX again (the ~tw expressions in steps-to-preview
were rendered as text). Reverted to the simpler approach: reuse the
existing SSR element and preserve its content entirely.
The copyright route not updating during SPA nav is a pre-existing
issue (path is an island parameter, not a reactive signal).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
JIT compiler:
- Fix jit_compile_lambda: resolve `compile` via symbol lookup in env
instead of embedding VmClosure in AST (CEK dispatches differently)
- Register eval-defcomp/eval-defisland/eval-defmacro runtime helpers
in browser kernel for bytecoded defcomp forms
- Disable broken .sxbc.json path (missing arity in nested code blocks),
use .sxbc text format only
- Mark JIT-failed closures as sentinel to stop retrying
CSSX in browser:
- Add cssx.sx symlink + cssx.sxbc to browser web stack
- Add flush-cssx! to orchestration.sx post-swap for SPA nav
- Add cssx.sx to compile-modules.js and mcp_tree.ml bytecode lists
SPA navigation:
- Fix double-fetch: check e.defaultPrevented in click delegation
(bind-event already handled the click)
- Fix layout destruction: change nav links from outerHTML to innerHTML
swap (outerHTML destroyed #main-panel when response lacked it)
- Guard JS popstate handler when SX engine is booted
- Rename sx-platform.js → sx-platform-2.js to bust immutable cache
Playwright tests:
- Add trackErrors() helper to all test specs
- Add SPA DOM comparison test (SPA nav vs fresh load)
- Add single-fetch + no-duplicate-elements test
- Improve MCP tool output: show failure details and error messages
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- AJAX requests (SX-Request: true) now render on main thread instead
of queueing behind slow full-page renders in worker pool
- Remove pushState from click handler — handle-history does it after
swap succeeds, preventing double-push that triggered popstate handler
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Root cause: _env_bind_hook mirrored ALL env_bind calls (including
lambda parameter bindings) to the shared VM globals table. Factory
functions like make-page-fn that return closures capturing different
values for the same param names (default-name, prefix, suffix) would
have the last call's values overwrite all previous closures' captured
state in globals. OP_GLOBAL_GET reads globals first, so all closures
returned the last factory call's values.
Fix: only sync root-env bindings (parent=None) to VM globals. Lambda
parameter bindings stay in their local env, found via vm_closure_env
fallback in OP_GLOBAL_GET.
Also in this commit:
- OP_CLOSURE propagates parent vm_closure_env to child closures
- Remove JIT globals injection (closure vars found via env chain)
- sx_server.ml: SX-Request header → returns text/sx (aser only)
- sx_server.ml: diagnostic endpoint GET /sx/_debug/{env,eval,route}
- sx_server.ml: page helper stubs for deep page rendering
- sx_server.ml: skip client-libs/ dir (browser-only definitions)
- adapter-html.sx: unknown components → HTML comment (not error)
- sx-platform.js: .sxbc fallback loader for bytecode modules
- Delete sx_http.ml (standalone HTTP server, unused)
- Delete stale .sxbc.json files (arity=0 bug, replaced by .sxbc)
- 7 new closure isolation tests in test-closure-isolation.sx
- mcp_tree.ml: emit arity + upvalue-count in .sxbc.json output
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Sx_compiler.compile/compile_module now emit arity (local slot count) in
the bytecode dict. MCP sx_build_bytecode serializes arity into .sxbc.json.
sx-platform.js passes arity through to K.loadModule(). Without this, the
VM allocated only 16 local slots per module frame.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Browser kernel:
- Add `parse` native fn (matches server: unwrap single, list for multiple)
- Restore env==global_env guard on _env_bind_hook (let bindings must not
leak to _vm_globals — caused JIT CSSX "Not callable: nil" errors)
- Add _env_bind_hook call in env_set_id so set! mutations sync to VM globals
- Fire _vm_global_set_hook from OP_DEFINE so VM defines sync back to CEK env
CEK evaluator:
- Replace recursive cek_run with iterative while loop using sx_truthy
(previous attempt used strict Bool true matching, broke in wasm_of_ocaml)
- Remove dead cek_run_iterative function
Web modules:
- Remove find-matching-route and parse-route-pattern stubs from
boot-helpers.sx that shadowed real implementations from router.sx
- Sync boot-helpers.sx to dist/static dirs for bytecode compilation
Platform (sx-platform.js):
- Set data-sx-ready attribute after boot completes (was only in boot-init
which sx-platform.js doesn't call — it steps through boot manually)
- Add document-level click delegation for a[sx-get] links as workaround
for bytecoded bind-event not attaching per-element listeners (VM closure
issue under investigation — bind-event runs but dom-add-listener calls
don't result in addEventListener)
Tests:
- New test_kernel.js: 24 tests covering env sync, parse, route matching,
host FFI/preventDefault, deep recursion
- New navigation test: "sx-get link fetches SX not HTML and preserves layout"
(currently catches layout breakage after SPA swap — known issue)
Known remaining issues:
- JIT CSSX failures: closure-captured variables resolve to nil in VM bytecode
- SPA content swap via execute-request breaks page layout
- Bytecoded bind-event doesn't attach per-element addEventListener (root
cause unknown — when listen-target guard appears to block despite element
being valid)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- request-handler.sx: replace all dots (not just `.(`) and auto-quote
undefined symbols as strings so 3-level URLs like
/sx/(geography.(reactive.(examples.counter))) resolve correctly
- sx-platform.js: register popstate handler (was missing from manual
boot sequence) and fetch full HTML for back/forward navigation
- sx_ref.ml: add CEK step limit (10M steps) checked every 4096 steps
so runaway renders return 500 instead of blocking the worker forever
- Rename test-runner.sx → runner-placeholder.sx to avoid `test-` skip
- Playwright config: pin testDir, single worker, ignore worktrees
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- def-store/use-store/clear-stores: OCaml primitives with global
mutable registry. Bypasses env scoping issues that prevented SX-level
stores from persisting across bytecode module boundaries.
- client? primitive: _is_client ref (false on server, true in browser).
Registered in primitives table for CALL_PRIM compatibility.
- Event-bridge island: rewritten to use document-level addEventListener
via effect + host-callback, fixing container-ref timing issue.
- Header island: uses def-store for idx/shade signals when client? is
true, plain signals when false (SSR compatibility).
- web-signals.sx: SX store definitions removed, OCaml primitives replace.
Isomorphic nav still fixme — client? works from K.eval but the JIT
"Not callable: nil" bug prevents proper primitive resolution during
render-to-dom hydration. Needs JIT investigation.
100 passed, 1 skipped, 0 failed.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Bytecode modules are now serialized as s-expressions (.sxbc) in addition
to JSON (.sxbc.json). The .sxbc format is the canonical representation —
content-addressable, parseable by the SX parser, and suitable for CID
referencing. Annotation layers (source maps, variable names, tests, docs)
can reference the bytecode CID without polluting the bytecode itself.
Format: (sxbc version hash (code :arity N :bytecode (...) :constants (...)))
The browser loader tries .sxbc first (via load-sxbc kernel primitive),
falls back to .sxbc.json. Caddy needs .sxbc MIME type to serve the new
format (currently 404s, JSON fallback works).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The sx-get links were doing full page refreshes because click handlers
never attached. Root causes: VM frame management bug, missing primitives,
CEK/VM type dispatch mismatch, and silent error swallowing.
Fixes:
- VM frame exhaustion: frames <- [] now properly pops to rest_frames
- length primitive: add alias for len in OCaml primitives
- call_sx_fn: use sx_call directly instead of eval_expr (CEK checks
for type "lambda" but VmClosure reports "function")
- Boot error surfacing: Sx.init() now has try/catch + failure summary
- Callback error surfacing: catch-all handler for non-Eval_error exceptions
- Silent JIT failures: log before CEK fallback instead of swallowing
- vm→env sync: loadModule now calls sync_vm_to_env()
- sx_build_bytecode MCP tool added for bytecode compilation
Tests: 50 new tests across test-vm.sx and test-vm-primitives.sx covering
nested VM calls, frame integrity, CEK bridge, primitive availability,
cross-module symbol resolution, and callback dispatch.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- compile-modules.js: Node.js build tool, all 23 .sx files compile to .sxbc.json
- api_load_module with shared globals (beginModuleLoad/endModuleLoad batch API)
- api_compile_module for runtime compilation
- sx-platform.js: bytecode-first loader with source fallback, JSON deserializer
- Deferred JIT enable (setTimeout after boot)
Known issues:
- WASM browser: loadModule loads but functions not accessible (env writeback
issue with interned keys)
- WASM browser: compileModule fails ("Not callable: nil" — compile-module
function from bytecode not working correctly in WASM context)
- Node.js js_of_ocaml: full roundtrip works (compile → load → call)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Wire up jit_call_hook in sx_browser.ml (same pattern as server)
- Deferred JIT: _jit_enabled flag, enabled after boot-init completes
(prevents "Undefined symbol" errors from compiling during .sx loading)
- enable-jit! native function called by sx-platform.js after boot
- sx-platform.js: async WASM kernel polling + JIT enable after init
- Error logging for JIT compile failures and runtime fallbacks
Performance: 858ms → 431ms (WASM CEK) → 101ms (WASM JIT)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Platform:
- sx-platform.js: extract ?v= query from script tag URL, append to
all .sx file XHR requests. Prevents stale cached .sx files.
Stepper performance:
- do-back: use rebuild-preview (pure SX→DOM render) instead of
replaying every do-step from 0. O(1) instead of O(n).
- Hydration effect: same rebuild-preview instead of step replay.
- Cookie save moved from do-step to button on-click handlers only.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
