[alex09x]

Problem

A Git-tracked dangling symlink needed by generated Swift bindings is absent from the remote workspace after sync. The local link exists before target/bindings does; the build creates that target later, and SwiftPM then needs the original link identity to resolve the generated file.

Change

• Add an optional full-workspace tracked-symlink manifest to SyncRequest; partial syncs do not claim ownership of the full link set.
• The client collects mode 120000 entries from Git, keeps the original relative targets, and excludes link aliases from the regular file manifest so a followed file link cannot overwrite its link.
• The gateway validates link paths and target confinement, creates links atomically, and keeps a gateway-local manifest so later full syncs remove only links it previously managed and whose targets still match.
• The gateway acknowledges support in the existing sync response. A new client refuses to run a command when a tracked symlink is present and the gateway cannot confirm support or reports a failed link.
• Old clients remain compatible because the request extension is optional and defaults to absent.

Reproduce and verify

Mitts Build 0.3.21, macOS ARM64:

• mitts test --locked -p prod-code-protocol --test transport_security_acceptance test_packet_capture_wire_confidentiality — 1 passed.
• mitts test --locked -p prod-code-gateway --lib 'sync::symlinks::tests::' — 2 passed. Covers dangling-link identity after the generated target appears, removal of a managed link, workspace-escape rejection, and the response acknowledgement.
• mitts test --locked -p prod-code-mcp --lib 'sync::push::tests::' — 6 passed. Covers sending tracked links, filtering a followed file link from ordinary file deltas, and refusing a legacy gateway before command execution.
• mitts test --locked -p prod-code-testkit --test wire_and_engines_1_scripted_gateway sync_messages_are_answered_as_if_the_tree_were_held — 1 passed.
• Mitts formatting checks for prod-code-gateway, prod-code-mcp, prod-code-protocol, and prod-code-testkit — passed with 0 diffs.
• Strict Clippy passed for prod-code-protocol. Strict Clippy for gateway and MCP is blocked by existing warnings in unrelated modules; one warning in the new gateway helper was fixed. No claim of a clean strict-Clippy run for those packages.

No performance claim. A live SwiftPM remote-exec run has not yet been done; the regression is covered by focused client and gateway tests, not a released-cluster test.

Measurements

None; no latency or performance claim.

Checks

The targeted Mitts tests above passed. No full test suite or live cluster was run.

Closes

Closes #1889

[alex09x]

Superseded by #1912, which now includes the tracked symlink protocol/client/gateway changes alongside ownership-aware sync for #1888 and #1895. Issue #1889 is linked from the consolidated PR and remains open until it merges.