Mirror of the 2026-05-05 Wear-OS fix: port the canonical client sync
spec (project_client_sync_semantics.md) into the Rust desktop client.
Before this change, server_sync::run_loop had a `UploadOutcome::Terminal`
branch that deleted the m4a + sidecar pair on any non-2xx + non-5xx
response (401, 413, 415, parse drift, audio read failures) and never
called mark_synced — so the marker stayed `synced_to_server=false` as a
non-removable ghost in the desktop UI. Same shape as the Wear-OS bug.
Changes:
- `UploadOutcome` reduced to two variants (`Succeeded` | `Transient`).
The Terminal arm in `run_loop` is gone; `delete_pair` only fires from
the success path.
- `post_upload` now classifies every failure mode as `Transient`:
4xx incl. 401, parse-ack drift on 200, file-read errors, multipart
build errors, and network errors. Backoff retries forever.
- New `CaseStore::cleanup_orphaned_unsynced(pending_case_ids, cutoff)`:
removes markers that are unsynced AND have no waiting upload pair AND
are older than a small grace window. Self-heals pre-spec ghosts.
- `run_startup_cleanup` gains a third sweep that calls
`cleanup_orphaned_unsynced` with `DEFAULT_ORPHAN_MARKER_GRACE = 5 min`,
matching the Wear-OS StartupCleanup contract.
- Tests inverted/added: `post_upload_transient_on_401`,
`post_upload_transient_on_2xx_unparseable_body`,
`former_terminal_401_keeps_pair_and_retries`, four new
`cleanup_orphaned_unsynced_*` cases, plus `sweeps_orphan_unsynced_marker`
and `keeps_unsynced_marker_with_pending_pair` integration tests.
Followup (out of scope): `UploadEvent::Failed.will_retry` can now only
be `true` and is vestigial. Removing it touches every Failed-event
consumer in app.rs/UI; left for a separate cleanup commit.
Brummel
a142725a8a