Update documentation to make a particular pitfall less likely.

[jkomoros]

This was the outcome of the whole saga documented in CT-1022, where Claude got confused for a whole day.

---

Summary by cubic

Updated docs and examples to prevent stack overflows when storing pattern instances and to favor on‑demand child pattern creation when patterns share parent cells. Also adds ACLs, a fetchProgram builtin, and modernized APIs and patterns; includes clear wrong vs correct examples and a working view selector tied to CT‑1022.

• New Features

  • “Upfront vs On‑Demand” docs section with a new sample pattern and INDEX entry; clearer wrong vs correct examples (CT‑1022).
  • Common Issues/Recipes expanded: derive+map vs ifElse, boxing pattern for sorting, wish() defaults, generateObject init/caching, llmDialog tool reliability, frame mismatch, transaction conflicts.
  • Space ACLs with CLI (acl ls/add/rm) and runtime/controller support.
  • New fetchProgram builtin with example and omnibox tool; compileAndRun handles empty inputs gracefully.
  • API/pattern updates: inline handlers, Cell.of(), computed(), JSX CellLike props; image input + LLM image/tool support; link tool implemented in pattern‑space; default app “Pages” label.

• Dependencies

  • Added Playwright 1.56.1.

^{Written for commit c423d24. Summary will update automatically on new commits.}

[cubic-dev-ai]

1 issue found across 2 files

Prompt for AI agents (all 1 issues)

Understand the root cause of the following 1 issues and fix them.


<file name="docs/common/PATTERNS.md">

<violation number="1" location="docs/common/PATTERNS.md:688">
The &quot;correct&quot; example references `randomId` without defining it, so the snippet will throw a reference error if copied. Please declare `randomId` (e.g., `const randomId = Math.random().toString(36).substring(2, 10);`) before using it.</violation>
</file>

_{React with 👍 or 👎 to teach cubic. Mention @cubic-dev-ai to give feedback, ask questions, or re-run the review.}

[cubic-dev-ai]

The "correct" example references randomId without defining it, so the snippet will throw a reference error if copied. Please declare randomId (e.g., const randomId = Math.random().toString(36).substring(2, 10);) before using it.

Prompt for AI agents

Address the following comment on docs/common/PATTERNS.md at line 688:

<comment>The &quot;correct&quot; example references `randomId` without defining it, so the snippet will throw a reference error if copied. Please declare `randomId` (e.g., `const randomId = Math.random().toString(36).substring(2, 10);`) before using it.</comment>

<file context>
@@ -662,6 +662,52 @@ const addItem = handler&lt;
+  undefined,
+  ({ charm, chatsList, isInitialized }) =&gt; {
+    if (!isInitialized.get()) {
+      chatsList.push({ [ID]: randomId, local_id: randomId, charm });
+      isInitialized.set(true);
+    }
</file context>

[seefeldb]

This way of using [ID] is generally not needed here (and the Math.random() specifically an anti-pattern once we go for actual causal ids). We should fix that in the upstream example as well. @bfollington

[seefeldb]

This might no longer be necessary since schemas are now derived for lift as well.

Would lift<{ charm: any, patternsList: Cell<Entry[]>, isInitialized: Cell<boolean>}, undefined>(({ charm, patternsList, isInitialized }) => { ....work?

[seefeldb]

I don't think this casting is necessary anymore either, and if it is, the big type refactor that is pending ought to fix this.

[cubic-dev-ai]

Reviewed changes from recent commits (found 14 issues).

14 issues found across 81 files

Prompt for AI agents (all 14 issues)

Understand the root cause of the following 14 issues and fix them.


<file name="packages/ts-transformers/test/fixtures/ast-transform/builder-conditional.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/ast-transform/builder-conditional.expected.tsx:24">
The derive callback destructures a non-existent `state` property from the recipe state object, so the predicate becomes undefined and the UI will always take the Non-positive branch. Replace the callback to accept the state object directly.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-operations.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-operations.expected.tsx:9">
`__ctHelpers.derive` invokes the callback with the raw cell value, so destructuring `({ count })` leaves `count` undefined and produces wrong results (e.g., NaN). Please keep the parameter as the bare value; the same fix is needed for the Double/Total lines.</violation>
</file>

<file name="packages/ts-transformers/src/utils/identifiers.ts">

<violation number="1" location="packages/ts-transformers/src/utils/identifiers.ts:21">
`isSafeIdentifierText` walks `name` one UTF-16 code unit at a time, so astral-plane identifiers (e.g. 𠮷) fail the `ts.isIdentifierPart` check and the transformer needlessly renames them. Iterate by Unicode code point instead of code unit to preserve valid identifiers.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-cell-map.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-cell-map.expected.tsx:103">
Deriving `typedCellRef` now destructures from an object, but the derive helper passes the array itself, so the empty-state condition always reads `true` and hides the charm list. Please keep the original `typedCellRef =&gt; ...` callback.</violation>

<violation number="2" location="packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-cell-map.expected.tsx:106">
The derived index callback now destructures an object, but `index` is a number. This makes the `Go to Charm` label render `NaN`. Please revert to the simple `index =&gt; index + 1` callback.</violation>

<violation number="3" location="packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-cell-map.expected.tsx:108">
Deriving both the list index and charm now destructures from objects even though the derive helper passes the value itself. This makes the charm label render `NaN` and throws when evaluating `charm[NAME]`. Please restore the original callbacks.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/closures/map-outer-element.input.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/closures/map-outer-element.input.tsx:15">
Each JSX element returned from state.items.map needs a stable key so React can reconcile list updates correctly.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/map-single-capture.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/map-single-capture.expected.tsx:10">
`derive` receives the array emitted by the `people` cell. Destructuring it as `{ people }` makes the inner `people` reference `undefined`, so `people.length` and `people.map(...)` will throw at runtime. Please keep the callback parameter as the array value.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/closures/map-computed-alias-side-effect.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/closures/map-computed-alias-side-effect.expected.tsx:45">
Using `nextKey()` inside the destructuring pattern causes subsequent renders to search for ever-changing property names (e.g. `value-1`, `value-2`), so `amount` becomes `undefined` after the first pass. Please keep the key stable across renders (e.g. restore the previous derive-based lookup).</violation>
</file>

<file name="packages/deno-web-test/utils.ts">

<violation number="1" location="packages/deno-web-test/utils.ts:84">
`Deno.copyFile` will throw if `dest`&#39;s parent directory is missing. The previous `@std/fs` copy helper created the directory tree, so this regression will break includes that target nested paths. Please ensure the destination directory exists before copying.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/method-chains.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/method-chains.expected.tsx:237">
__ctHelpers.derive receives the primitive string value for name, but the callback now destructures ({ name }) and then calls name.trim(). Because the input isn’t wrapped in an object with a name property, name is undefined at runtime and this path throws. Please keep providing name as an object so the callback gets a defined string.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/optional-chain-predicate.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/optional-chain-predicate.expected.tsx:8">
Destructuring `{ items }` here breaks the predicate: the callback now receives `undefined`, so the &quot;No items&quot; message renders even when items exist. Revert to using the array parameter directly.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/map-array-length-conditional.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/map-array-length-conditional.expected.tsx:7">
`derive` passes the array value from the `list` cell into the callback. Destructuring `{ list }` from that array will throw at runtime, breaking the fixture. Please keep the callback parameter as the array itself.</violation>
</file>

<file name="packages/ts-transformers/src/transformers/builtins/derive.ts">

<violation number="1" location="packages/ts-transformers/src/transformers/builtins/derive.ts:212">
When only capture expressions are present, this returns the raw expression, so derive is invoked as `derive(pattern, ({ pattern }) =&gt; ...)`. The parameter still destructures an object, but we now pass a plain value, so the binding becomes undefined and breaks the transform.</violation>
</file>

_{React with 👍 or 👎 to teach cubic. Mention @cubic-dev-ai to give feedback, ask questions, or re-run the review.}

[cubic-dev-ai]

The derive callback destructures a non-existent state property from the recipe state object, so the predicate becomes undefined and the UI will always take the Non-positive branch. Replace the callback to accept the state object directly.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/ast-transform/builder-conditional.expected.tsx at line 24:

<comment>The derive callback destructures a non-existent `state` property from the recipe state object, so the predicate becomes undefined and the UI will always take the Non-positive branch. Replace the callback to accept the state object directly.</comment>

<file context>
@@ -21,7 +21,7 @@ export default recipe({
         [NAME]: state.label,
         [UI]: (&lt;section&gt;
-        {__ctHelpers.ifElse(__ctHelpers.derive({ state, state_count: state.count }, ({ state: state, state_count: _v2 }) =&gt; state &amp;&amp; _v2 &gt; 0), &lt;p&gt;Positive&lt;/p&gt;, &lt;p&gt;Non-positive&lt;/p&gt;)}
+        {__ctHelpers.ifElse(__ctHelpers.derive(state, ({ state }) =&gt; state &amp;&amp; state.count &gt; 0), &lt;p&gt;Positive&lt;/p&gt;, &lt;p&gt;Non-positive&lt;/p&gt;)}
       &lt;/section&gt;),
     };
</file context>

Suggested change

	{__ctHelpers.ifElse(__ctHelpers.derive(state, ({ state }) => state && state.count > 0), <p>Positive</p>, <p>Non-positive</p>)}
	{__ctHelpers.ifElse(__ctHelpers.derive(state, (state) => state && state.count > 0), <p>Positive</p>, <p>Non-positive</p>)}

[cubic-dev-ai]

__ctHelpers.derive invokes the callback with the raw cell value, so destructuring ({ count }) leaves count undefined and produces wrong results (e.g., NaN). Please keep the parameter as the bare value; the same fix is needed for the Double/Total lines.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-operations.expected.tsx at line 9:

<comment>`__ctHelpers.derive` invokes the callback with the raw cell value, so destructuring `({ count })` leaves `count` undefined and produces wrong results (e.g., NaN). Please keep the parameter as the bare value; the same fix is needed for the Double/Total lines.</comment>

<file context>
@@ -6,9 +6,9 @@ export default recipe(&quot;OpaqueRefOperations&quot;, (_state) =&gt; {
-        &lt;p&gt;Next: {__ctHelpers.derive(count, count =&gt; count + 1)}&lt;/p&gt;
-        &lt;p&gt;Double: {__ctHelpers.derive(count, count =&gt; count * 2)}&lt;/p&gt;
-        &lt;p&gt;Total: {__ctHelpers.derive(price, price =&gt; price * 1.1)}&lt;/p&gt;
+        &lt;p&gt;Next: {__ctHelpers.derive(count, ({ count }) =&gt; count + 1)}&lt;/p&gt;
+        &lt;p&gt;Double: {__ctHelpers.derive(count, ({ count }) =&gt; count * 2)}&lt;/p&gt;
+        &lt;p&gt;Total: {__ctHelpers.derive(price, ({ price }) =&gt; price * 1.1)}&lt;/p&gt;
</file context>

Suggested change

	<p>Next: {__ctHelpers.derive(count, ({ count }) => count + 1)}</p>
	<p>Next: {__ctHelpers.derive(count, count => count + 1)}</p>

[cubic-dev-ai]

isSafeIdentifierText walks name one UTF-16 code unit at a time, so astral-plane identifiers (e.g. 𠮷) fail the ts.isIdentifierPart check and the transformer needlessly renames them. Iterate by Unicode code point instead of code unit to preserve valid identifiers.

Prompt for AI agents

Address the following comment on packages/ts-transformers/src/utils/identifiers.ts at line 21:

<comment>`isSafeIdentifierText` walks `name` one UTF-16 code unit at a time, so astral-plane identifiers (e.g. 𠮷) fail the `ts.isIdentifierPart` check and the transformer needlessly renames them. Iterate by Unicode code point instead of code unit to preserve valid identifiers.</comment>

<file context>
@@ -0,0 +1,152 @@
+    return false;
+  }
+  for (let i = 1; i &lt; name.length; i++) {
+    const code = name.codePointAt(i)!;
+    if (!ts.isIdentifierPart(code, ts.ScriptTarget.ESNext)) {
+      return false;
</file context>

[cubic-dev-ai]

Deriving both the list index and charm now destructures from objects even though the derive helper passes the value itself. This makes the charm label render NaN and throws when evaluating charm[NAME]. Please restore the original callbacks.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-cell-map.expected.tsx at line 108:

<comment>Deriving both the list index and charm now destructures from objects even though the derive helper passes the value itself. This makes the charm label render `NaN` and throws when evaluating `charm[NAME]`. Please restore the original callbacks.</comment>

<file context>
@@ -100,12 +100,12 @@ export default recipe(&quot;Charms Launcher&quot;, () =&gt; {
+                  Go to Charm {__ctHelpers.derive(index, ({ index }) =&gt; index + 1)}
                 &lt;/ct-button&gt;
-                &lt;span&gt;Charm {__ctHelpers.derive(index, index =&gt; index + 1)}: {__ctHelpers.derive(charm, charm =&gt; charm[NAME] || &quot;Unnamed&quot;)}&lt;/span&gt;
+                &lt;span&gt;Charm {__ctHelpers.derive(index, ({ index }) =&gt; index + 1)}: {__ctHelpers.derive(charm, ({ charm }) =&gt; charm[NAME] || &quot;Unnamed&quot;)}&lt;/span&gt;
               &lt;/li&gt;))}
           &lt;/ul&gt;)}
</file context>

Suggested change

	<span>Charm {__ctHelpers.derive(index, ({ index }) => index + 1)}: {__ctHelpers.derive(charm, ({ charm }) => charm[NAME] || "Unnamed")}</span>
	<span>Charm {__ctHelpers.derive(index, index => index + 1)}: {__ctHelpers.derive(charm, charm => charm[NAME] || "Unnamed")}</span>

[cubic-dev-ai]

The derived index callback now destructures an object, but index is a number. This makes the Go to Charm label render NaN. Please revert to the simple index => index + 1 callback.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-cell-map.expected.tsx at line 106:

<comment>The derived index callback now destructures an object, but `index` is a number. This makes the `Go to Charm` label render `NaN`. Please revert to the simple `index =&gt; index + 1` callback.</comment>

<file context>
@@ -100,12 +100,12 @@ export default recipe(&quot;Charms Launcher&quot;, () =&gt; {
             {typedCellRef.map((charm: any, index: number) =&gt; (&lt;li&gt;
                 &lt;ct-button onClick={goToCharm({ charm })}&gt;
-                  Go to Charm {__ctHelpers.derive(index, index =&gt; index + 1)}
+                  Go to Charm {__ctHelpers.derive(index, ({ index }) =&gt; index + 1)}
                 &lt;/ct-button&gt;
-                &lt;span&gt;Charm {__ctHelpers.derive(index, index =&gt; index + 1)}: {__ctHelpers.derive(charm, charm =&gt; charm[NAME] || &quot;Unnamed&quot;)}&lt;/span&gt;
</file context>

Suggested change

	Go to Charm {__ctHelpers.derive(index, ({ index }) => index + 1)}
	Go to Charm {__ctHelpers.derive(index, index => index + 1)}

[cubic-dev-ai]

Deno.copyFile will throw if dest's parent directory is missing. The previous @std/fs copy helper created the directory tree, so this regression will break includes that target nested paths. Please ensure the destination directory exists before copying.

Prompt for AI agents

Address the following comment on packages/deno-web-test/utils.ts at line 84:

<comment>`Deno.copyFile` will throw if `dest`&#39;s parent directory is missing. The previous `@std/fs` copy helper created the directory tree, so this regression will break includes that target nested paths. Please ensure the destination directory exists before copying.</comment>

<file context>
@@ -65,3 +64,33 @@ export function summarize(results: TestFileResults[]): Summary {
+  } else if (stat.isDirectory) {
+    await copyDir(src, dest);
+  } else {
+    await Deno.copyFile(src, dest);
+  }
+}
</file context>

[cubic-dev-ai]

__ctHelpers.derive receives the primitive string value for name, but the callback now destructures ({ name }) and then calls name.trim(). Because the input isn’t wrapped in an object with a name property, name is undefined at runtime and this path throws. Please keep providing name as an object so the callback gets a defined string.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/method-chains.expected.tsx at line 237:

<comment>__ctHelpers.derive receives the primitive string value for name, but the callback now destructures ({ name }) and then calls name.trim(). Because the input isn’t wrapped in an object with a name property, name is undefined at runtime and this path throws. Please keep providing name as an object so the callback gets a defined string.</comment>

<file context>
@@ -192,44 +234,63 @@ export default recipe({
                 },
                 required: [&quot;element&quot;, &quot;params&quot;]
-            } as const satisfies __ctHelpers.JSONSchema, ({ element, params: {} }) =&gt; (&lt;li&gt;{__ctHelpers.derive(element, element =&gt; element.trim().toLowerCase().replace(&quot; &quot;, &quot;-&quot;))}&lt;/li&gt;)), {})}
+            } as const satisfies __ctHelpers.JSONSchema, ({ element: name, params: {} }) =&gt; (&lt;li&gt;{__ctHelpers.derive(name, ({ name }) =&gt; name.trim().toLowerCase().replace(&quot; &quot;, &quot;-&quot;))}&lt;/li&gt;)), {})}
         &lt;/ul&gt;
 
</file context>

Suggested change

	} as const satisfies __ctHelpers.JSONSchema, ({ element: name, params: {} }) => (<li>{__ctHelpers.derive(name, ({ name }) => name.trim().toLowerCase().replace(" ", "-"))}</li>)), {})}
	} as const satisfies __ctHelpers.JSONSchema, ({ element: name, params: {} }) => (<li>{__ctHelpers.derive({ state: { name } }, ({ state }) => state.name.trim().toLowerCase().replace(" ", "-"))}</li>)), {})}

[cubic-dev-ai]

Destructuring { items } here breaks the predicate: the callback now receives undefined, so the "No items" message renders even when items exist. Revert to using the array parameter directly.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/optional-chain-predicate.expected.tsx at line 8:

<comment>Destructuring `{ items }` here breaks the predicate: the callback now receives `undefined`, so the &quot;No items&quot; message renders even when items exist. Revert to using the array parameter directly.</comment>

<file context>
@@ -5,7 +5,7 @@ export default recipe(&quot;Optional Chain Predicate&quot;, () =&gt; {
         [NAME]: &quot;Optional chain predicate&quot;,
         [UI]: (&lt;div&gt;
-        {__ctHelpers.derive(items, items =&gt; !items?.length &amp;&amp; &lt;span&gt;No items&lt;/span&gt;)}
+        {__ctHelpers.derive(items, ({ items }) =&gt; !items?.length &amp;&amp; &lt;span&gt;No items&lt;/span&gt;)}
       &lt;/div&gt;),
     };
</file context>

Suggested change

	{__ctHelpers.derive(items, ({ items }) => !items?.length && <span>No items</span>)}
	{__ctHelpers.derive(items, items => !items?.length && <span>No items</span>)}

[cubic-dev-ai]

derive passes the array value from the list cell into the callback. Destructuring { list } from that array will throw at runtime, breaking the fixture. Please keep the callback parameter as the array itself.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/map-array-length-conditional.expected.tsx at line 7:

<comment>`derive` passes the array value from the `list` cell into the callback. Destructuring `{ list }` from that array will throw at runtime, breaking the fixture. Please keep the callback parameter as the array itself.</comment>

<file context>
@@ -4,7 +4,7 @@ export default recipe(&quot;MapArrayLengthConditional&quot;, (_state) =&gt; {
     return {
         [UI]: (&lt;div&gt;
-        {__ctHelpers.derive(list, list =&gt; list.length &gt; 0 &amp;&amp; (&lt;div&gt;
+        {__ctHelpers.derive(list, ({ list }) =&gt; list.length &gt; 0 &amp;&amp; (&lt;div&gt;
             {list.map((name) =&gt; (&lt;span&gt;{name}&lt;/span&gt;))}
           &lt;/div&gt;))}
</file context>

Suggested change

	{__ctHelpers.derive(list, ({ list }) => list.length > 0 && (<div>
	{__ctHelpers.derive(list, (list) => list.length > 0 && (<div>

[cubic-dev-ai]

When only capture expressions are present, this returns the raw expression, so derive is invoked as derive(pattern, ({ pattern }) => ...). The parameter still destructures an object, but we now pass a plain value, so the binding becomes undefined and breaks the transform.

Prompt for AI agents

Address the following comment on packages/ts-transformers/src/transformers/builtins/derive.ts at line 212:

<comment>When only capture expressions are present, this returns the raw expression, so derive is invoked as `derive(pattern, ({ pattern }) =&gt; ...)`. The parameter still destructures an object, but we now pass a plain value, so the binding becomes undefined and breaks the transform.</comment>

<file context>
@@ -116,23 +175,48 @@ function createParameterForEntries(
+    if (!first.done) {
+      const node = first.value;
+      if (node.expression &amp;&amp; node.properties.size === 0) {
+        return [node.expression];
+      }
+    }
</file context>

Suggested change

	return [node.expression];
	return [factory.createObjectLiteralExpression(properties, false)];

[cubic-dev-ai]

Reviewed changes from recent commits (found 18 issues).

18 issues found across 85 files

Prompt for AI agents (all 18 issues)

Understand the root cause of the following 18 issues and fix them.


<file name="packages/ts-transformers/test/opaque-ref/map-callbacks.test.ts">

<violation number="1" location="packages/ts-transformers/test/opaque-ref/map-callbacks.test.ts:74">
This assertion no longer verifies that the negated `ifElse` condition is wrapped in `__ctHelpers.derive`, so the test could pass even if the derive call disappears. Please assert the entire `__ctHelpers.derive(state.charms.length, ({ state }) =&gt; !state.charms.length)` snippet to keep coverage intact.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/optional-chain-captures.input.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/optional-chain-captures.input.tsx:19">
Each element returned from state.items.map should have a stable key prop so React can reconcile the list correctly. Please add an appropriate key to the &lt;span&gt;.</violation>
</file>

<file name="packages/ts-transformers/docs/hierarchical-params-spec.md">

<violation number="1" location="packages/ts-transformers/docs/hierarchical-params-spec.md:120">
This doc claims the transformer now caches computed property aliases via `derive(...)`, but the actual fixtures still destructure `[nextKey()]` directly, so the side-effectful call runs on every invocation. Please update the documentation (or land the caching change) so it matches current behavior.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/map-array-length-conditional.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/map-array-length-conditional.expected.tsx:7">
The derive callback now destructures `{ list }`, but the input provided is the array from the `list` cell. That destructuring makes `list` undefined, so `list.length` throws and the UI breaks. Please keep the callback receiving the array itself.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/method-chains.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/method-chains.expected.tsx:237">
`__ctHelpers.derive` receives the primitive `name`, but the callback now destructures `{ name }`, so at runtime it throws because strings aren’t objects. Change the argument to pass an object if you need to destructure.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/optional-chain-predicate.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/optional-chain-predicate.expected.tsx:8">
The derive callback should receive the cell value (the items array). Destructuring into `{ items }` makes `items` undefined, so the predicate always returns true and the UI incorrectly shows “No items”.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/map-single-capture.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/map-single-capture.expected.tsx:10">
The derive callback now destructures `{ people }`, but derive passes the people array itself, so the destructured `people` becomes undefined and `people.length` throws. Please keep the callback parameter as the array.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/optional-element-access.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/optional-element-access.expected.tsx:8">
The derive callback now destructures `{ list }`, but derive(list, f) passes the array value itself, so `list` inside the callback becomes `undefined` and the condition is wrong. Restore the direct parameter so the array contents are checked correctly.</violation>
</file>

<file name="packages/ts-transformers/test/derive/create-derive-call.test.ts">

<violation number="1" location="packages/ts-transformers/test/derive/create-derive-call.test.ts:58">
The derive call prints the fallback parameter alias (e.g. `=&gt; _v2`), not the renamed property `_v1_1`, so this assertion will fail. Update the expected substring to match the actual alias.</violation>
</file>

<file name="packages/ts-transformers/src/utils/identifiers.ts">

<violation number="1" location="packages/ts-transformers/src/utils/identifiers.ts:21">
Iterating with `i++` causes surrogate pairs to be rechecked as separate code units, so astral-plane identifiers (e.g., “𝑥”) are incorrectly rejected; adjust the loop to advance past both units when a code point uses a surrogate pair.</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/ast-transform/builder-conditional.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/ast-transform/builder-conditional.expected.tsx:24">
The derive callback destructures `{ state }`, but the argument is the state object itself, so the local `state` becomes `undefined` and the condition always fails.</violation>
</file>

<file name="packages/deno-web-test/utils.ts">

<violation number="1" location="packages/deno-web-test/utils.ts:84">
`Deno.copyFile` will throw if `dirname(dest)` does not already exist, so copying includes to nested destinations will now fail (previously `@std/fs.copy` created those directories). Please ensure the parent directory exists before calling `Deno.copyFile` (in both the plain-file and resolved-symlink branches).</violation>
</file>

<file name="packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-operations.expected.tsx">

<violation number="1" location="packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-operations.expected.tsx:9">
`derive` invokes the callback with the raw cell value, not an object. Destructuring `{ count }` here makes `count` undefined, so the rendered value becomes `NaN`. Please keep the positional parameter.</violation>

<violation number="2" location="packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-operations.expected.tsx:10">
`derive` gives this callback the numeric cell value, so destructuring `{ count }` returns undefined and the output becomes `NaN`. Please keep the simple numeric parameter.</violation>

<violation number="3" location="packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-operations.expected.tsx:11">
`derive` hands this callback the numeric value from `price`, not an object. Destructuring `{ price }` yields undefined, so the total renders as `NaN`. Please keep the positional argument.</violation>
</file>

<file name="packages/ts-transformers/src/transformers/builtins/derive.ts">

<violation number="1" location="packages/ts-transformers/src/transformers/builtins/derive.ts:148">
When there is only a single capture reference, the callback parameter should remain a plain identifier; otherwise derive(foo, ({ foo }) =&gt; ...) destructures the value incorrectly and returns undefined.</violation>
</file>

<file name="packages/ts-transformers/src/closures/transformer.ts">

<violation number="1" location="packages/ts-transformers/src/closures/transformer.ts:1017">
Binding each capture root to the object returned by buildHierarchicalParamsValue means methods like state.someMethod() now execute with `this` bound to a synthetic clone rather than the original closure object, breaking instance-dependent logic. Please bind roots to the original expression (or otherwise preserve the original receiver) instead of cloning partial objects.</violation>
</file>

<file name="packages/patterns/on-demand-pattern-creation.tsx">

<violation number="1" location="packages/patterns/on-demand-pattern-creation.tsx:84">
Use `&lt;ct-render $cell={currentView} /&gt;` (or lift/derive) to render the selected recipe; inserting the Cell itself just stringifies the object so the chosen view never appears.</violation>
</file>

_{React with 👍 or 👎 to teach cubic. Mention @cubic-dev-ai to give feedback, ask questions, or re-run the review.}

[cubic-dev-ai]

This assertion no longer verifies that the negated ifElse condition is wrapped in __ctHelpers.derive, so the test could pass even if the derive call disappears. Please assert the entire __ctHelpers.derive(state.charms.length, ({ state }) => !state.charms.length) snippet to keep coverage intact.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/opaque-ref/map-callbacks.test.ts at line 74:

<comment>This assertion no longer verifies that the negated `ifElse` condition is wrapped in `__ctHelpers.derive`, so the test could pass even if the derive call disappears. Please assert the entire `__ctHelpers.derive(state.charms.length, ({ state }) =&gt; !state.charms.length)` snippet to keep coverage intact.</comment>

<file context>
@@ -52,26 +52,26 @@ describe(&quot;OpaqueRef map callbacks&quot;, () =&gt; {
     assertStringIncludes(
       output,
-      &quot;ifElse(__ctHelpers.derive(state.charms.length, _v1 =&gt; !_v1)&quot;,
+      &quot;({ state }) =&gt; !state.charms.length&quot;,
     );
   });
</file context>

Suggested change

	"({ state }) => !state.charms.length",
	"__ctHelpers.derive(state.charms.length, ({ state }) => !state.charms.length)",

[cubic-dev-ai]

Each element returned from state.items.map should have a stable key prop so React can reconcile the list correctly. Please add an appropriate key to the .

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/optional-chain-captures.input.tsx at line 19:

<comment>Each element returned from state.items.map should have a stable key prop so React can reconcile the list correctly. Please add an appropriate key to the &lt;span&gt;.</comment>

<file context>
@@ -0,0 +1,24 @@
+      &lt;div&gt;
+        &lt;span&gt;{state.maybe?.value}&lt;/span&gt;
+        {state.items.map((item) =&gt; (
+          &lt;span&gt;{item.maybe?.value ?? 0}&lt;/span&gt;
+        ))}
+      &lt;/div&gt;
</file context>

[cubic-dev-ai]

This doc claims the transformer now caches computed property aliases via derive(...), but the actual fixtures still destructure [nextKey()] directly, so the side-effectful call runs on every invocation. Please update the documentation (or land the caching change) so it matches current behavior.

Prompt for AI agents

Address the following comment on packages/ts-transformers/docs/hierarchical-params-spec.md at line 120:

<comment>This doc claims the transformer now caches computed property aliases via `derive(...)`, but the actual fixtures still destructure `[nextKey()]` directly, so the side-effectful call runs on every invocation. Please update the documentation (or land the caching change) so it matches current behavior.</comment>

<file context>
@@ -1,460 +1,205 @@
-  }
-}
+// New output caches once and threads the key through derive
+const __ct_val_key = nextKey();
+({ element }) =&gt; derive({ element, __ct_val_key }, ({ element, __ct_val_key: key }) =&gt; element[key])
 ```
</file context>

[cubic-dev-ai]

The derive callback now destructures { list }, but the input provided is the array from the list cell. That destructuring makes list undefined, so list.length throws and the UI breaks. Please keep the callback receiving the array itself.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/map-array-length-conditional.expected.tsx at line 7:

<comment>The derive callback now destructures `{ list }`, but the input provided is the array from the `list` cell. That destructuring makes `list` undefined, so `list.length` throws and the UI breaks. Please keep the callback receiving the array itself.</comment>

<file context>
@@ -4,7 +4,7 @@ export default recipe(&quot;MapArrayLengthConditional&quot;, (_state) =&gt; {
     return {
         [UI]: (&lt;div&gt;
-        {__ctHelpers.derive(list, list =&gt; list.length &gt; 0 &amp;&amp; (&lt;div&gt;
+        {__ctHelpers.derive(list, ({ list }) =&gt; list.length &gt; 0 &amp;&amp; (&lt;div&gt;
             {list.map((name) =&gt; (&lt;span&gt;{name}&lt;/span&gt;))}
           &lt;/div&gt;))}
</file context>

Suggested change

	{__ctHelpers.derive(list, ({ list }) => list.length > 0 && (<div>
	{__ctHelpers.derive(list, (list) => list.length > 0 && (<div>

[cubic-dev-ai]

__ctHelpers.derive receives the primitive name, but the callback now destructures { name }, so at runtime it throws because strings aren’t objects. Change the argument to pass an object if you need to destructure.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/method-chains.expected.tsx at line 237:

<comment>`__ctHelpers.derive` receives the primitive `name`, but the callback now destructures `{ name }`, so at runtime it throws because strings aren’t objects. Change the argument to pass an object if you need to destructure.</comment>

<file context>
@@ -192,44 +234,63 @@ export default recipe({
                 },
                 required: [&quot;element&quot;, &quot;params&quot;]
-            } as const satisfies __ctHelpers.JSONSchema, ({ element, params: {} }) =&gt; (&lt;li&gt;{__ctHelpers.derive(element, element =&gt; element.trim().toLowerCase().replace(&quot; &quot;, &quot;-&quot;))}&lt;/li&gt;)), {})}
+            } as const satisfies __ctHelpers.JSONSchema, ({ element: name, params: {} }) =&gt; (&lt;li&gt;{__ctHelpers.derive(name, ({ name }) =&gt; name.trim().toLowerCase().replace(&quot; &quot;, &quot;-&quot;))}&lt;/li&gt;)), {})}
         &lt;/ul&gt;
 
</file context>

Suggested change

	} as const satisfies __ctHelpers.JSONSchema, ({ element: name, params: {} }) => (<li>{__ctHelpers.derive(name, ({ name }) => name.trim().toLowerCase().replace(" ", "-"))}</li>)), {})}
	} as const satisfies __ctHelpers.JSONSchema, ({ element: name, params: {} }) => (<li>{__ctHelpers.derive({ name }, ({ name }) => name.trim().toLowerCase().replace(" ", "-"))}</li>)), {})}

[cubic-dev-ai]

derive gives this callback the numeric cell value, so destructuring { count } returns undefined and the output becomes NaN. Please keep the simple numeric parameter.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-operations.expected.tsx at line 10:

<comment>`derive` gives this callback the numeric cell value, so destructuring `{ count }` returns undefined and the output becomes `NaN`. Please keep the simple numeric parameter.</comment>

<file context>
@@ -6,9 +6,9 @@ export default recipe(&quot;OpaqueRefOperations&quot;, (_state) =&gt; {
-        &lt;p&gt;Double: {__ctHelpers.derive(count, count =&gt; count * 2)}&lt;/p&gt;
-        &lt;p&gt;Total: {__ctHelpers.derive(price, price =&gt; price * 1.1)}&lt;/p&gt;
+        &lt;p&gt;Next: {__ctHelpers.derive(count, ({ count }) =&gt; count + 1)}&lt;/p&gt;
+        &lt;p&gt;Double: {__ctHelpers.derive(count, ({ count }) =&gt; count * 2)}&lt;/p&gt;
+        &lt;p&gt;Total: {__ctHelpers.derive(price, ({ price }) =&gt; price * 1.1)}&lt;/p&gt;
       &lt;/div&gt;),
</file context>

Suggested change

	<p>Double: {__ctHelpers.derive(count, ({ count }) => count * 2)}</p>
	<p>Double: {__ctHelpers.derive(count, count => count * 2)}</p>

[cubic-dev-ai]

derive invokes the callback with the raw cell value, not an object. Destructuring { count } here makes count undefined, so the rendered value becomes NaN. Please keep the positional parameter.

Prompt for AI agents

Address the following comment on packages/ts-transformers/test/fixtures/jsx-expressions/opaque-ref-operations.expected.tsx at line 9:

<comment>`derive` invokes the callback with the raw cell value, not an object. Destructuring `{ count }` here makes `count` undefined, so the rendered value becomes `NaN`. Please keep the positional parameter.</comment>

<file context>
@@ -6,9 +6,9 @@ export default recipe(&quot;OpaqueRefOperations&quot;, (_state) =&gt; {
-        &lt;p&gt;Next: {__ctHelpers.derive(count, count =&gt; count + 1)}&lt;/p&gt;
-        &lt;p&gt;Double: {__ctHelpers.derive(count, count =&gt; count * 2)}&lt;/p&gt;
-        &lt;p&gt;Total: {__ctHelpers.derive(price, price =&gt; price * 1.1)}&lt;/p&gt;
+        &lt;p&gt;Next: {__ctHelpers.derive(count, ({ count }) =&gt; count + 1)}&lt;/p&gt;
+        &lt;p&gt;Double: {__ctHelpers.derive(count, ({ count }) =&gt; count * 2)}&lt;/p&gt;
+        &lt;p&gt;Total: {__ctHelpers.derive(price, ({ price }) =&gt; price * 1.1)}&lt;/p&gt;
</file context>

Suggested change

	<p>Next: {__ctHelpers.derive(count, ({ count }) => count + 1)}</p>
	<p>Next: {__ctHelpers.derive(count, count => count + 1)}</p>

[cubic-dev-ai]

When there is only a single capture reference, the callback parameter should remain a plain identifier; otherwise derive(foo, ({ foo }) => ...) destructures the value incorrectly and returns undefined.

Prompt for AI agents

Address the following comment on packages/ts-transformers/src/transformers/builtins/derive.ts at line 148:

<comment>When there is only a single capture reference, the callback parameter should remain a plain identifier; otherwise derive(foo, ({ foo }) =&gt; ...) destructures the value incorrectly and returns undefined.</comment>

<file context>
@@ -35,75 +40,129 @@ export interface DeriveCallOptions {
+    );
+  }
+
+  const shouldInlineSoleBinding = bindings.length === 1 &amp;&amp;
+    captureTree.size === 0 &amp;&amp;
+    fallbackEntries.length === 1 &amp;&amp;
</file context>

[cubic-dev-ai]

Binding each capture root to the object returned by buildHierarchicalParamsValue means methods like state.someMethod() now execute with this bound to a synthetic clone rather than the original closure object, breaking instance-dependent logic. Please bind roots to the original expression (or otherwise preserve the original receiver) instead of cloning partial objects.

Prompt for AI agents

Address the following comment on packages/ts-transformers/src/closures/transformer.ts at line 1017:

<comment>Binding each capture root to the object returned by buildHierarchicalParamsValue means methods like state.someMethod() now execute with `this` bound to a synthetic clone rather than the original closure object, breaking instance-dependent logic. Please bind roots to the original expression (or otherwise preserve the original receiver) instead of cloning partial objects.</comment>

<file context>
@@ -1201,52 +991,49 @@ function createRecipeCallWithParams(
-        factory.createIdentifier(varName),
-        expr,
+        createSafePropertyName(rootName, factory),
+        buildHierarchicalParamsValue(rootNode, rootName, factory),
       ),
     );
</file context>

[cubic-dev-ai]

Use <ct-render $cell={currentView} /> (or lift/derive) to render the selected recipe; inserting the Cell itself just stringifies the object so the chosen view never appears.

Prompt for AI agents

Address the following comment on packages/patterns/on-demand-pattern-creation.tsx at line 84:

<comment>Use `&lt;ct-render $cell={currentView} /&gt;` (or lift/derive) to render the selected recipe; inserting the Cell itself just stringifies the object so the chosen view never appears.</comment>

<file context>
@@ -0,0 +1,95 @@
+          &lt;div style={{ marginTop: &quot;16px&quot;, border: &quot;1px solid #e0e0e0&quot;, borderRadius: &quot;4px&quot; }}&gt;
+            {ifElse(
+              hasView,
+              &lt;div&gt;{currentView}&lt;/div&gt;,
+              &lt;div style={{ padding: &quot;2rem&quot;, textAlign: &quot;center&quot;, color: &quot;#666&quot; }}&gt;
+                Choose a view above
</file context>