id(worker-poc): TS isolate host for plaza guests — scaffold + counter smoke (#2271) by dezren39 · Pull Request #3726 · developing-today/code

dezren39 · 2026-11-01T14:29:31Z

PoC for #2271 (from #2057): one example world running unmodified in a Worker isolate, journal equality vs the native wasmtime host.

This increment (scaffold + isolate-side smoke):

pkgs/id/worker-poc/src/guest.ts — PlazaGuest drives only the plaza_* ABI with the native host's alloc/free + output discipline (sandbox.rs is the reference); bytes path (Node) and module path (workerd) both supported.
src/manifest.ts — hosted loader refuses portability=native and declared memory over the 64MB hosted ceiling, each with the reason named (acceptance 4).
src/worker.ts — one Durable Object per world; SQLite journal is the source of truth; /cold-start forces restore via plaza_restore.
smoke/counter-smoke.mjs — prebuilt counter.wasm, seed 0 + inc×3.

Verified (laptop, Node 24): view/records show count=0..3 per step; guest-level cold start (restore step-2 snapshot → inc) reproduces the step-3 snapshot hash 4e07408562bedb8b60ce05c1decfe3ad16b72230967de01f640b7e4729b49fce exactly; both loader refusals asserted. Smoke: PASS.

Remaining (later increments on this branch): native reference runner comparison over the same sequence; tic-tac-toe scripted sequence; DO-level forced cold start under wrangler dev.

Pre-registered differences (fuel vs CPU-time; refusal-at-load vs trap-at-run) are on #2271. No changes to the native sandbox, guests, or the plaza ABI.

Refs #2271

^{Need help on this PR? Tag @codesmith-bot with what you need.}

coderabbitai · 2026-11-01T14:29:39Z

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Files selected for processing: 16

pkgs/id/nix-common.nix
pkgs/id/tests/worker_poc_reference.rs
pkgs/id/worker-poc/.gitignore
pkgs/id/worker-poc/README.md
pkgs/id/worker-poc/compare/compare.mjs
pkgs/id/worker-poc/compare/do-cold-start.mjs
pkgs/id/worker-poc/compare/isolate-runner.mjs
pkgs/id/worker-poc/compare/native-reference.jsonl
pkgs/id/worker-poc/package.json
pkgs/id/worker-poc/smoke/counter-smoke.mjs
pkgs/id/worker-poc/smoke/participant-clamp.mjs
pkgs/id/worker-poc/src/guest.ts
pkgs/id/worker-poc/src/manifest.ts
pkgs/id/worker-poc/src/worker.ts
pkgs/id/worker-poc/tsconfig.json
pkgs/id/worker-poc/wrangler.toml

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chatgpt-codex-connector · 2026-11-01T14:29:45Z

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-01T23:30:41.003203Z	`13ac9c8`	Manual request

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Reviewed commit: 1b2a6ca62a

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chatgpt-codex-connector · 2026-11-01T14:34:59Z

+      .toArray();
+    const guest = await loadHostedModule(MANIFEST, COUNTER_WASM as WebAssembly.Module, SEED);
+    if (rows.length > 0) {
+      guest.restore(rows[0].snapshot as Uint8Array);


Convert SQLite snapshot buffers before restoring the guest

After a journaled step, /cold-start or a real eviction restores a SQLite BLOB, which workerd returns as an ArrayBuffer (also handled explicitly in pkgs/pkarr-worker/src/index.ts:75–83). This type assertion does not convert it to a Uint8Array. Consequently, copyInput() sees an undefined .length, copies no snapshot bytes, and calls plaza_restore with length zero. Reproducing with the counter resets its count to 0 while retaining the journaled step number. Wrap the stored buffer in a Uint8Array before restoring it.

Useful? React with 👍 / 👎.

Fixed in a1a5683: journal snapshots pass through asBytes() (Uint8Array passthrough, ArrayBuffer wrapped) before plaza_restore. — queue worker lane D, task 5598.

chatgpt-codex-connector · 2026-11-01T14:34:59Z

+    const guest = await loadHostedModule(MANIFEST, COUNTER_WASM as WebAssembly.Module, SEED);
+    if (rows.length > 0) {
+      guest.restore(rows[0].snapshot as Uint8Array);
+      this.step = rows[0].step as number;
+    }
+    this.guest = guest;


Serialize lazy guest initialization across requests

When two /step requests arrive at a fresh or forced-cold object, both can pass the null check and independently instantiate a guest while this await yields. Each request then updates its own initial model, and both results are journaled: a concurrent counter reproduction produces steps 1 and 2 with count=1 for both, permanently losing an increment. Durable Objects permit asynchronous interleaving; Cloudflare documents blockConcurrencyWhile for protecting initialization. Share an initialization promise or otherwise serialize initialization, including coordination with /cold-start.

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Fixed in a1a5683: lazy initialization is shared through a single guestPromise (cleared on failure), and all request handling — including /cold-start — is serialized through a per-object promise chain, so two requests can never instantiate competing guests. — task 5598.

chatgpt-codex-connector · 2026-11-01T14:34:59Z

+    const mem = new Uint8Array(this.ex.memory.buffer);
+    if (outputPtr + len > mem.length) throw new Error("guest returned output outside linear memory");
+    return mem.slice(outputPtr, outputPtr + len);


Normalize output pointers before checking memory bounds

If a guest returns a negative i32 output pointer, the upper-bound check can accept it and slice() interprets it as an offset from the end of memory. For example, pointer -3 and length 2 return the two bytes near the memory's end instead of rejecting the invalid range. This silently corrupts views, records, or snapshots and differs from sandbox.rs, which casts the pointer to unsigned before validating it. Normalize the pointer with >>> 0 before both the bounds check and the slice.

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Fixed in a1a5683: readOutput normalizes the pointer with >>> 0 before the bounds check and the slice, matching sandbox.rs. — task 5598.

chatgpt-codex-connector · 2026-11-01T14:34:59Z

@@ -0,0 +1 @@
+{"description":"PoC (#2271): plaza_* example worlds running unmodified in a Worker isolate, journal equality vs the native wasmtime host.","devDependencies":{"typescript":"^5.6.0","wrangler":"^3.90.0"},"name":"id-worker-poc","private":true,"scripts":{"dev":"wrangler dev","smoke":"node smoke/counter-smoke.mjs","typecheck":"tsc --noEmit"},"type":"module"}


Declare the new Wrangler tool in the shared Nix dependencies

The new Wrangler development dependency is declared only in this npm manifest, leaving it absent from the shared Nix development environment. pkgs/id/AGENTS.md explicitly requires new development dependencies to be added through nix-common.nix; TypeScript is already provided there, but Wrangler is not. Add Wrangler through the required shared dependency definition so the supported Nix environment includes the tool needed for this PoC.

AGENTS.md reference: pkgs/id/AGENTS.md:L34-L34

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Fixed in a1a5683: wrangler added to pkgs/id/nix-common.nix next to typescript, per pkgs/id/AGENTS.md. — task 5598.

chatgpt-codex-connector · 2026-11-01T14:34:59Z

+      const { participant, event } = (await req.json()) as { participant: number; event: string };
+      guest.update(participant, enc.encode(event));


Validate step inputs before mutating the guest

A request containing {"participant":null,"event":"inc"} passes the unchecked type assertion and increments the counter because guest.update() coerces the participant to zero. The subsequent INSERT fails on journal.participant's NOT NULL constraint, but neither the guest mutation nor the step increment is reverted. Reproducing against SQLite leaves count 1 with an empty journal; the next valid request persists step 2/count 2, incorporating an event that failed and was never journaled. Validate the request fields before calling the guest, and discard or restore the mutated guest if persistence fails so unsuccessful requests cannot contaminate later snapshots.

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Fixed in a1a5683: /step validates participant (non-negative integer) and event (non-empty string) before any guest mutation and returns 400 otherwise; if the journal INSERT throws, the guest is discarded so the next request restores from the journal — an unjournaled event cannot contaminate later snapshots. — task 5598.

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chatgpt-codex-connector · 2026-11-01T15:37:32Z

+      const snapshotHash = await sha256Hex(snapshot);
+      this.step += 1;
+      this.sql.exec(


Serialize updates through snapshot hashing and journal insertion

When concurrent /step requests reach an already-initialized guest, this await allows another update before the first snapshot is journaled. If the digests complete out of order, journal step numbers follow digest completion rather than guest-update order. A Node/SQLite reproduction with reversed digest completion persisted step 1 with count=2, followed by step 2 with count=1, making the latest journal snapshot stale. This is separate from lazy-initialization concurrency and remains possible even with a shared initialization promise. Serialize the entire update/hash/insert operation so journal order matches guest evolution.

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Fixed in a1a5683: the entire update -> snapshot -> hash -> journal-insert sequence runs inside the per-object serialized chain (fetch delegates to a promise-chain mutex), so journal step order always matches guest evolution order. — task 5598.

All six Codex findings on PR #3726 dispositioned in code: - SQLite BLOB snapshots normalized via asBytes() before plaza_restore (workerd returns ArrayBuffer; restore copied zero bytes before). - Lazy guest init shared through one promise; all request handling serialized through a per-object promise chain, so update -> hash -> journal insert is one unit and journal order matches guest order. - /step validates participant/event before mutating the guest; on journal-insert failure the guest is discarded so an unjournaled event cannot contaminate later snapshots. - guest readOutput normalizes the i32 output pointer with >>> 0 before bounds check and slice, matching sandbox.rs. - wrangler declared in pkgs/id/nix-common.nix per AGENTS.md. Verified: npm run smoke PASS, tsc --noEmit clean (laptop).

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Reviewed commit: a1a5683f0c

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chatgpt-codex-connector · 2026-11-01T19:41:58Z

+  update(participant: number, event: Uint8Array): void {
+    const { ptr, len, allocationLen } = this.copyInput(event);
+    try {
+      this.model = this.ex.plaza_update(this.model, participant | 0, ptr, len);


Clamp participant IDs instead of wrapping them

When PlazaGuest receives a participant ID above the signed i32 range, participant | 0 wraps it instead of matching the native host's clamp to i32::MAX in sandbox.rs. In particular, 4294967296 becomes participant zero. This changes state evolution for existing guests: with roc-chat.wasm, updating with event "x" appends input for participant 2147483647, but not for 4294967296, because roc-chat/main.roc routes participant zero through its host-event handler. The currently wired counter ignores participant IDs, so its smoke test does not expose this discrepancy. Clamp the ID as the native host does before passing it to the guest.

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Fixed in 13ac9c8 (pushed to this branch): PlazaGuest.update now clamps the participant ID to i32::MAX before the | 0 conversion, matching sandbox.rs (i32::try_from(participant).unwrap_or(i32::MAX)). Verified behaviorally with roc-chat.wasm: participant 4294967296 now appends input exactly like 2147483647, and no longer collapses into participant 0 — regression pinned in smoke/participant-clamp.mjs (npm run participant-clamp), passing. — task 5598, lane F

PlazaGuest drives only the plaza_* ABI with the native hosts alloc/free and output discipline; hosted loader refuses portability=native and declared memory over the 64MB ceiling, naming the reason. Durable Object host journals every step (snapshot/view/records/hash) in SQLite and restores via plaza_restore after a forced cold start. Counter smoke (Node 24, laptop): seed 0 + inc x3 gives count=0..3 in view and records; guest-level cold start reproduces the step-3 snapshot hash 4e07408562... exactly; both loader refusals asserted. Native-runner comparison and tic-tac-toe sequence are the next increments.

All six Codex findings on PR #3726 dispositioned in code: - SQLite BLOB snapshots normalized via asBytes() before plaza_restore (workerd returns ArrayBuffer; restore copied zero bytes before). - Lazy guest init shared through one promise; all request handling serialized through a per-object promise chain, so update -> hash -> journal insert is one unit and journal order matches guest order. - /step validates participant/event before mutating the guest; on journal-insert failure the guest is discarded so an unjournaled event cannot contaminate later snapshots. - guest readOutput normalizes the i32 output pointer with >>> 0 before bounds check and slice, matching sandbox.rs. - wrangler declared in pkgs/id/nix-common.nix per AGENTS.md. Verified: npm run smoke PASS, tsc --noEmit clean (laptop).

…2271) Native reference runner (tests/worker_poc_reference.rs) drives the roc-counter and tic-tac-toe scripted sequences through the native Sandbox and emits per-step (view, records, snapshot) lines; worker-poc/compare diffs them against the isolate host: 13/13 steps equal, snapshot sha256 included, each host asserting its own forced cold start mid-sequence. do-cold-start.mjs proves the DO level under wrangler dev: /cold-start restore and a full dev restart (fresh DO instance) both restore step 2 from the SQLite journal, and step 3 matches the native hash. Branch rebased onto current main (the old base snapshot carried a misplaced derive in cli.rs that no longer compiles; main has it fixed).

dezren39 · 2026-11-01T21:50:02Z

New increment pushed (c378b57, branch rebased onto current origin/main): the native-vs-isolate equality harness and the DO-level cold start — the last open checklist items for #2271.

pkgs/id/tests/worker_poc_reference.rs — native reference runner over the roc-counter and tic-tac-toe scripted sequences (native Sandbox), emitting per-step (view, records, snapshot); asserts native cold-start equality mid-sequence. cargo test --test worker_poc_reference PASS.
worker-poc/compare/compare.mjs — diffs the isolate host against the native reference per step, snapshot sha256 included: PASS, 13/13 steps equal.
worker-poc/compare/do-cold-start.mjs — DO-level proof under wrangler dev: /cold-start restore + full dev-server restart (fresh DO instance) both restore step 2 from the SQLite journal; step-3 hash equals the native reference. PASS.
Counter smoke still PASS; README checklist updated.

@chatgpt-codex-connector please re-review the new head.

chatgpt-codex-connector · 2026-11-01T21:51:42Z

Codex Review: Didn't find any major issues. Already looking forward to the next diff.

Reviewed commit: c378b57367

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… host (#2271)

dezren39 · 2026-11-01T23:29:08Z

Record clarification (task 5598, lane F): the six earlier Codex findings on this PR (snapshot buffer conversion, lazy-init serialization, output-pointer normalization, wrangler in nix-common.nix, step-input validation, update/hash/journal serialization) are fixed on this branch in e68f4cd — verified at head by direct code read. The thread replies citing a1a5683 pointed at a parallel commit that was never on this branch (its parent is the original scaffold); the fixes themselves are present here via e68f4cd. The one live finding — participant ID clamp — is now fixed in 13ac9c8 with a regression smoke. Note on ownership: this PR is the queue task 5598 branch (queue/5598-…); dezren39 authorship is the fleet account, not a Drew-owned hard stop (the two earlier parks on that reading were the conflation corrected across the fleet today).

@codex review

chatgpt-codex-connector · 2026-11-01T23:30:39Z

Codex Review: Didn't find any major issues. More of your lovely PRs please.

Reviewed commit: 13ac9c80b2

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dezren39 requested a review from a team as a code owner November 1, 2026 14:29

This was referenced Nov 1, 2026

id: PoC: one example world running unmodified in a Worker isolate — journal equality vs the native wasmtime host (from #2057) #2271

Closed

Phase 2: production ingest enforces only p2panda-auth membership #168

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dezren39 force-pushed the queue/5598-2271-worker-isolate-poc branch from 1b2a6ca to 3cf4ae5 Compare November 1, 2026 15:34

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id: design: ID serverless edition v1 (Cloudflare Workers) #2046

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dezren39 added 3 commits November 1, 2026 15:28

dezren39 force-pushed the queue/5598-2271-worker-isolate-poc branch from a1a5683 to c378b57 Compare November 1, 2026 21:48

fix(id): clamp worker-poc participant IDs to i32::MAX like the native…

13ac9c8

… host (#2271)

dezren39 merged commit 10e4a89 into main Nov 1, 2026
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dezren39 deleted the queue/5598-2271-worker-isolate-poc branch November 1, 2026 23:31

		@@ -0,0 +1 @@
		{"description":"PoC (#2271): plaza_* example worlds running unmodified in a Worker isolate, journal equality vs the native wasmtime host.","devDependencies":{"typescript":"^5.6.0","wrangler":"^3.90.0"},"name":"id-worker-poc","private":true,"scripts":{"dev":"wrangler dev","smoke":"node smoke/counter-smoke.mjs","typecheck":"tsc --noEmit"},"type":"module"} No newline at end of file

		const { participant, event } = (await req.json()) as { participant: number; event: string };
		guest.update(participant, enc.encode(event));

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