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perf(core): intern path parts to eliminate hot-path array allocations #42

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56d077f
perf(core): intern hot-path appendPathParts allocations via WeakMap c…
senrecep Apr 8, 2026
2a6e931
bench(core): add path parts interning allocation benchmark
senrecep Apr 8, 2026
f6ee396
fix(core): prevent dot-split path corruption and fix test identity as…
senrecep Apr 8, 2026
d9752ad
bench(core): fix path-interning benchmark to exercise _wrapItem inter…
senrecep Apr 8, 2026
0a6e506
fix(core): add dotted-key path regression test for array item properties
senrecep Apr 8, 2026
90016d0
perf(core): cap _internAppend inner Map to prevent unbounded memory g…
senrecep Apr 8, 2026
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7 changes: 7 additions & 0 deletions .changeset/append-path-parts-interning.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
---
"@geajs/core": patch
---

### @geajs/core (patch)

- **Hot-path path-parts interning**: Replace per-call `appendPathParts` allocations in `_wrapItem` and array mutation handlers (splice, push/unshift, pop/shift) with a module-level `WeakMap` cache keyed on stable `baseParts` references, eliminating redundant array allocations in list-heavy workloads.
29 changes: 24 additions & 5 deletions packages/gea/src/lib/store.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,25 @@ function appendPathParts(pathParts: string[], propStr: string): string[] {
return [...pathParts, propStr]
}

// Module-level cache: WeakMap<baseParts, Map<segment, result>>.
// Keys are the stable cached baseParts arrays produced by _makePathCache,
// so entries are GC'd automatically when the owning proxy is collected.
const _appendCache = new WeakMap<string[], Map<string, string[]>>()

function _internAppend(baseParts: string[], segment: string): string[] {
let inner = _appendCache.get(baseParts)
if (inner === undefined) {
inner = new Map()
_appendCache.set(baseParts, inner)
}
let result = inner.get(segment)
if (result === undefined) {
result = baseParts.length > 0 ? [...baseParts, segment] : [segment]
inner.set(segment, result)
}
return result
}

function joinPath(basePath: string, seg: string | number): string {
return basePath ? `${basePath}.${seg}` : String(seg)
}
Expand Down Expand Up @@ -155,7 +174,7 @@ const getByPathParts = (obj: any, pathParts: string[]): any => pathParts.reduce(
function _wrapItem(store: Store, arr: any[], i: number, basePath: string, baseParts: string[]): any {
const raw = arr[i]
return shouldWrapNestedReactiveValue(raw)
? _createProxy(store, raw, joinPath(basePath, i), appendPathParts(baseParts, String(i)))
? _createProxy(store, raw, joinPath(basePath, i), _internAppend(baseParts, String(i)))
: raw
Comment on lines 171 to 175

@coderabbitai coderabbitai Bot Apr 8, 2026

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⚠️ Potential issue | 🟠 Major

Don't reuse raw-object proxies for array-index paths.

_wrapItem() is building an index-scoped path here, but _createProxy() still checks proxyCache before it derives cachedArrayMeta. After unshift/splice/sort/reverse, a previously seen element object can come back with its old proxy, so nested writes keep emitting the old basePath/pathParts (for example, items.0.* after the object moved to items.1). Please derive the array metadata before the raw-object cache lookup and keep index-scoped proxies out of the global proxyCache path.

🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@packages/gea/src/lib/store.ts` around lines 170 - 174, _wrapItem is creating
index-scoped proxies for array elements which allows _createProxy to return a
stale proxy from proxyCache with incorrect cachedArrayMeta (wrong
basePath/baseParts) after array mutations; fix by deriving array-specific
metadata (cachedArrayMeta or equivalent) inside _wrapItem before calling
_createProxy and ensure _createProxy does not use the global proxyCache for
index-scoped paths (i.e., do not cache proxies whose pathParts include
numeric/index segments). Update _wrapItem, _createProxy, and the proxyCache
lookup logic so index-scoped proxies are created fresh and non-indexed object
proxies remain cached; reference functions/variables: _wrapItem, _createProxy,
proxyCache, cachedArrayMeta, joinPath, _internAppend.

}

Expand Down Expand Up @@ -721,11 +740,11 @@ function _interceptArray(
const changes: StoreChange[] = []
for (let i = 0; i < removed.length; i++) {
const idx = String(start + i)
changes.push(_mkChange('delete', idx, arr, appendPathParts(baseParts, idx), undefined, removed[i]))
changes.push(_mkChange('delete', idx, arr, _internAppend(baseParts, idx), undefined, removed[i]))
}
for (let i = 0; i < items.length; i++) {
const idx = String(start + i)
changes.push(_mkChange('add', idx, arr, appendPathParts(baseParts, idx), items[i]))
changes.push(_mkChange('add', idx, arr, _internAppend(baseParts, idx), items[i]))
}
if (changes.length > 0) _pushAndSchedule(store, changes, p)
return removed
Expand All @@ -743,7 +762,7 @@ function _interceptArray(
} else {
const changes: StoreChange[] = []
for (let i = 0; i < rawItems.length; i++)
changes.push(_mkChange('add', String(i), arr, appendPathParts(baseParts, String(i)), rawItems[i]))
changes.push(_mkChange('add', String(i), arr, _internAppend(baseParts, String(i)), rawItems[i]))
_pushAndSchedule(store, changes, p)
}
return arr.length
Expand All @@ -758,7 +777,7 @@ function _interceptArray(
;(Array.prototype as any)[method].call(arr)
_pushAndSchedule(
store,
[_mkChange('delete', String(idx), arr, appendPathParts(baseParts, String(idx)), undefined, removed)],
[_mkChange('delete', String(idx), arr, _internAppend(baseParts, String(idx)), undefined, removed)],
p,
)
return removed
Expand Down