[vercel-eddie]

Summary

• Replace the one-shot CopyFiles RPC with a read-only FUSE mount backed by a new BridgeFileSystemService on the existing proxy gRPC connection.
• Each VolumeMount on the source container is exposed at the same absolute path inside the devcontainer, so rotated tokens, updated ConfigMaps, and projected volumes (IRSA / workload identity) reflect the live pod state instead of a stale snapshot.
• Devcontainer feature option renamed copyFiles → mountPaths; create now adds SYS_ADMIN, --device /dev/fuse, and apparmor:unconfined only when the source has VolumeMounts.

Design

• Proto (proto/bridge/v1/filesystem.proto): BridgeFileSystemService with Stat, ReadDir, ReadFile (offset/size chunked at 1 MiB), ReadLink. Stateless — every RPC takes an absolute path.
• Server (pkg/fsmount/server.go): registered on the same gRPC port as the proxy. Authorizes every path against the configured --mount-roots allowlist; returns PermissionDenied for anything outside.
• Client (pkg/fsmount/client.go): go-fuse v2 nodes that proxy each VFS op to a gRPC call. 5 s attribute/entry cache, FOPEN_KEEP_CACHE. Writes return EROFS.
• Wiring: injectProxyImage derives --mount-roots from the source container's VolumeMounts; GetMetadata advertises them; bridge intercept calls fsmount.Mount per path once the gRPC connection is up. Mount failures are non-fatal — network interception still works without /dev/fuse.
• Removed: CopyFiles RPC, copyFilesFromProxy in intercept, the now-unused volumeMountPaths helper in bundle.go.

Test plan

• go test ./... — all packages green
• New unit tests for fsmount.Server: allowlist auth, Stat/ReadDir/ReadFile/ReadLink, error mapping
• New unit tests for injectProxyImage: emits --mount-roots when source has VolumeMounts, omits it otherwise
• New linux-tagged integration test that runs the gRPC server in-process and verifies the FUSE round trip (auto-skips when /dev/fuse is unavailable)
• Manual: bridge create -c userservice and confirm /var/run/secrets/... and other source mounts are live inside the devcontainer
• Manual: confirm rotated IRSA tokens become visible without restarting intercept

Notes

• Also fixes a pre-existing build failure on main in pkg/k8s/resources/transforms_test.go (stale Resource slice / Transform method API).
• pkg/mutagen is still in the tree but was already unreferenced — left alone to keep this PR focused.

🤖 Generated with Claude Code

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	golang/​github.com/​hanwen/​go-fuse/​v2@​v2.10.1

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