Nightly fails to launch on macOS 26.5.1 — RBSRequestErrorDomain Code=5 / POSIX 163 (Launchd job spawn failed)

Environment

• T3 Code (Nightly) 0.0.29-nightly.20260721.864
• macOS 26.5.1 (build 25F80), Apple Silicon

Problem

After the nightly auto-updated this morning, the app no longer launches. No window, no crash report. Launching via open gives:

The application /Applications/T3 Code (Nightly).app cannot be opened for an unexpected reason,
error=Error Domain=RBSRequestErrorDomain Code=5 "Launch failed."
NSUnderlyingError: Domain=NSPOSIXErrorDomain Code=163 "Launchd job spawn failed"

The Squirrel relaunch after the update fails too (ShipIt_stderr.log):

Could not launch application at file:///Applications/T3%20Code%20(Nightly).app/:
NSCocoaErrorDomain Code=256 ... NSOSStatusErrorDomain Code=-10810 "kLSUnknownErr"

The bundle itself is fine: codesign --verify --deep --strict passes, spctl accepts it (Notarized Developer ID), and the staple validates.

Root cause

macOS 26.3+ validates restricted entitlements strictly at spawn time, and launchd rejects the app because of the com.apple.developer.associated-domains (webcredentials:clerk.t3.codes) entitlement + embedded.provisionprofile ("T3 Code Developer ID Passkeys") combination. Other apps are hitting the same error 163 on macOS 26.x, e.g. steipete/RepoBar#29 and manaflow-ai/cmux#1739 (there the com.apple.developer.web-browser restricted entitlement).

Verified locally: copying the bundle, deleting Contents/embedded.provisionprofile, and re-signing ad-hoc with only the com.apple.security.cs.* entitlements makes the app launch normally on the same machine.

Expected

Nightly launches on macOS 26.5, or ships without the passkeys profile until the macOS-side validation issue is resolved.

Start by inspecting the nightly app packaging and signing configuration, focusing on embedded.provisionprofile and the associated-domains entitlement. Reproduce the failure with open and review ShipIt_stderr.log; done means the nightly app launches on macOS 26.5 without removing its valid code signature.