Normalize application Mach-O identities before macOS bundle audit #410

Parent: #227
Release consumer: SceneTech/AppScene#130

Problem

The exact installed-SDK Code OSS Release at AppScene cac13616 / WebScene 54158141 reaches recursive macOS bundle auditing, then fails before signing because three third-party Node native modules carry producer-machine absolute LC_ID_DYLIB values:

• server/node_modules/@github/copilot-darwin-arm64/prebuilds/darwin-arm64/runtime.node
• server/extensions/copilot/node_modules/@github/copilot/sdk/prebuilds/darwin-arm64/cli-native.node
• server/extensions/copilot/node_modules/@github/copilot/sdk/prebuilds/darwin-arm64/runtime.node

The identifiers point below /Users/runner/work/copilot-agent-runtime/.... These are dylib identities, not unresolved runtime dependencies. WebScene's package_macos.py already relocates SDK framework identities and recursively audits every bundled Mach-O, but it does not normalize identities of application-supplied .node/.dylib payloads before that audit. The fail-closed audit correctly rejects the absolute producer path.

Proposed fix

Before recursive audit and signing, enumerate bounded regular Mach-O files inside the bundle and normalize every non-system absolute LC_ID_DYLIB to a loader-safe identity such as @rpath/<basename>. Do not weaken audit_macos_bundle.py: the post-normalization audit must continue rejecting any remaining absolute identity, dependency or rpath. Preserve slice normalization, dependency-closure checks, nested signing order and immutable installed-SDK behavior.

Normalization must be deterministic, fail closed on malformed load commands, avoid symlink traversal and record enough evidence to prove exactly which identities changed. Application-specific source patching is not acceptable because the generic SDK packager owns relocatable macOS bundle output.

Acceptance

• A fixture .node with an absolute producer LC_ID_DYLIB is normalized and passes the existing recursive audit/signing flow.
• System identities and already relative identities remain byte-for-byte unchanged.
• Absolute dependencies and rpaths remain rejected; the fix cannot turn them into silent basename matches.
• The exact three Code OSS Copilot native modules lose every /Users/runner/work/... identifier and remain loadable by Node 24.
• Recursive architecture, deployment-target, dependency-closure, signing and no-browser evidence still pass.
• The installed SDK inventory is unchanged before/after packaging.
• Repeated qualification stays within the existing 25,000-entry bound and adds a measured time/RSS budget for the scan.

Exact reproduction

Run the Release through the installed AppScene CLI with the 2,868-file SDK archive SHA-256 6f2495278484a811323d9565dea0cc0abb79110540678d6ca02877980fc4ed7a. Packaging stops in audit_macos_bundle.validate_install_name() on libcli_native.dylib after the unchanged server payload is staged.