Branch C of the multi-library data-model rollout. Implements the
operational maintenance pipeline pinned in CLAUDE.md → "Multi-library
data model" / "Library availability and safety". Branches A and B
land first; this branch builds on top.
New module: src/library_maintenance.rs
Three idempotent passes the watcher runs every tick after the
per-library ingest loop:
1. Missing-file scan (per online library)
For each Online library, load a paginated page of image_exif rows
(IMAGE_EXIF_MISSING_SCAN_PAGE_SIZE, default 500), stat() each one,
and delete rows whose source file is NotFound. Permission/IO
errors are skipped, never deleted. Capped at
IMAGE_EXIF_MISSING_DELETE_CAP_PER_TICK (default 200) per library
per tick — so a pathological mount that returns NotFound for
everything can't wipe the table in one cycle. Cursor advances
across ticks, wraps on partial-page returns, and naturally cycles
through the entire library over many minutes. Skipped wholesale
for Stale libraries via the existing probe gate.
2. Back-ref refresh (DB-only)
For face_detections / tagged_photo / photo_insights: any
hash-keyed row whose (library_id, rel_path) no longer matches an
image_exif row, but whose content_hash does, is repointed at a
surviving image_exif location. Pure SQL with EXISTS guards so
rows whose hash is fully orphaned are left alone (the orphan GC
handles those). Idempotent; no availability gate needed.
This is what makes a recent → archive move invisible to readers:
when pass 1 retires the lib-A row, pass 2 pivots tags / faces /
insights to lib-B's surviving path before any client notices.
3. Orphan GC (destructive)
Hash-keyed derived rows whose content_hash has no image_exif
referent are GC-eligible. Two-tick consensus: a hash must be
observed orphaned on two consecutive ticks AND every library must
be Online for both. A single Stale tick within the window cancels
all pending deletes (they remain marked but won't be promoted) —
they're re-evaluated next tick. The pending set lives in
OrphanGcState (in-memory); a watcher restart resets it, which can
only delay a delete, never cause one. Hashes that re-appear in
image_exif between ticks are "revived" from the pending set
(handles transient share unmount / remount).
Two new ExifDao methods:
- list_rel_paths_for_library_page(library_id, limit, offset) for
the paginated missing-file scan.
- (count_for_library landed in Branch A.)
Watcher wiring (main.rs)
Per-library: missing-file scan inside the existing per-library
loop, after process_new_files, gated by the same probe check that
already protects ingest. After the loop: reconcile (Branch B),
back-ref refresh, then run_orphan_gc. The maintenance connection is
opened once per tick (image_api::database::connect), used by all
three DB-only passes, and dropped at end of tick.
CLAUDE.md gains a "Maintenance pipeline" subsection that describes
the three passes and their interaction with the existing
availability-and-safety policy.
Tests: 225 pass (217 from Branch B + 8 new in library_maintenance
covering back-ref refresh including the fully-orphaned no-op case,
two-tick GC consensus, Stale-tick consensus reset, image_exif
re-appearance revival, multi-table delete, and the
all_libraries_online helper).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
263e27e108