A Proxy used as an array prototype is treated as absent — its traps never run on indexed reads

[proggeramlug]

array_custom_prototype in crates/perry-runtime/src/array/indexing_proto_chain.rs returns None for a Proxy prototype. Every caller reads None as "no custom prototype", so the array falls back to the default Array.prototype chain and the proxy's traps never run on indexed reads.

The in-source comment says a Proxy "keeps its existing dedicated handling in the in / property-get arms" — that handling does not cover the indexed read path.

                          node                      perry
inherited via proxy       "proxy-four"              undefined
get trap                  fired                     not fired
inherited hole            visible                   lost
index -1                  1                         -1

Repro

secret-tests/cases/adversarial/recent/26_array_deep_and_proxy_prototypes.ts

Relationship to other issues

Separable from the chain-depth defect, but the same file and likely the same fix window. #9221 was closed 2026-09-02 without covering this.

Done when

Case 26 matches node.

[proggeramlug]

Fixed by #9809, landed on main via merge train #9817. The train merged as its own branch, so the close-keyword never fired — closing manually, verified on main by patch-id.