feat(versions): schema and VersionDao for hash-keyed photo versions

photo_versions links a version's content_hash to its primary original's;
photo_version_references keeps provenance-only reference photos;
photo_version_display holds the global display choice. VersionDao covers
linking (chains flatten to the root), the display choice, per-original
summaries for /photos, the hidden-row set for non-SQL listings, and the
copy of the original's date/GPS/camera onto version rows. Also the SQL
predicate listings use to hide a version while its original is reachable.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

migrations/2026-10-30-000000_add_photo_versions/down.sql

@@ -0,0 +1,3 @@
+DROP TABLE IF EXISTS photo_version_display;
+DROP TABLE IF EXISTS photo_version_references;
+DROP TABLE IF EXISTS photo_versions;

migrations/2026-10-30-000000_add_photo_versions/up.sql

@@ -0,0 +1,41 @@
+-- Photo versions (#191): an AI restoration, upscale or edit that sits on
+-- disk near its original and is shown as the *same photo*.
+--
+-- The link is hash-keyed like every other derived table (CLAUDE.md →
+-- "Multi-library data model"): a version records the blake3
+-- `content_hash` of its primary original, so the link survives moves,
+-- renames and an archive handoff. File name and location are hints only.
+-- The version keeps its own `image_exif` row, so it still downloads and
+-- thumbnails on its own; listings hide it while its original is reachable
+-- in the current view (same rule as `duplicate_of_hash`).
+
+-- A file is a version of at most one original.
+CREATE TABLE photo_versions (
+    version_hash  TEXT PRIMARY KEY NOT NULL,
+    original_hash TEXT NOT NULL,
+    kind          TEXT NOT NULL,      -- restored | upscale | edit
+    source        TEXT NOT NULL,      -- xmp | name | backfill | api
+    created_at    BIGINT NOT NULL,
+    -- Denormalized back-ref to a live image_exif row for the version, kept
+    -- current by the back-ref refresh pass (same pattern as face_detections).
+    library_id    INTEGER NOT NULL,
+    rel_path      TEXT NOT NULL
+);
+CREATE INDEX idx_photo_versions_original ON photo_versions(original_hash);
+
+-- Reference photos (extra context fed to the model). Provenance only: a
+-- reference is never hidden or grouped because of the version.
+CREATE TABLE photo_version_references (
+    version_hash   TEXT NOT NULL,
+    reference_hash TEXT NOT NULL,
+    PRIMARY KEY (version_hash, reference_hash)
+);
+CREATE INDEX idx_photo_version_references_ref ON photo_version_references(reference_hash);
+
+-- The global (not per-user) choice of which file represents a photo.
+-- No row = show the original.
+CREATE TABLE photo_version_display (
+    original_hash TEXT PRIMARY KEY NOT NULL,
+    display_hash  TEXT NOT NULL,
+    decided_at    BIGINT NOT NULL
+);

src/database/mod.rs

@@ -54,6 +54,7 @@ pub mod reconcile;
 pub mod schema;
 pub mod search_dao;
 pub mod user_ai_prefs_dao;
+pub mod version_dao;
 
 pub use calendar_dao::{CalendarEventDao, SqliteCalendarEventDao};
 pub use daily_summary_dao::{DailySummaryDao, InsertDailySummary, SqliteDailySummaryDao};
@@ -71,6 +72,7 @@ pub use precomputed_reel_dao::{PrecomputedReelDao, SqlitePrecomputedReelDao};
 pub use preview_dao::{PreviewDao, SqlitePreviewDao};
 pub use search_dao::{SearchHistoryDao, SqliteSearchHistoryDao};
 pub use user_ai_prefs_dao::{SqliteUserAiPrefsDao, UserAiPrefsDao};
+pub use version_dao::{SqliteVersionDao, VersionDao};
 
 pub trait UserDao {
     fn create_user(&mut self, user: &str, password: &str) -> Option<User>;

src/database/schema.rs

@@ -345,6 +345,33 @@ diesel::table! {
     }
 }
 
+diesel::table! {
+    photo_version_display (original_hash) {
+        original_hash -> Text,
+        display_hash -> Text,
+        decided_at -> BigInt,
+    }
+}
+
+diesel::table! {
+    photo_version_references (version_hash, reference_hash) {
+        version_hash -> Text,
+        reference_hash -> Text,
+    }
+}
+
+diesel::table! {
+    photo_versions (version_hash) {
+        version_hash -> Text,
+        original_hash -> Text,
+        kind -> Text,
+        source -> Text,
+        created_at -> BigInt,
+        library_id -> Integer,
+        rel_path -> Text,
+    }
+}
+
 diesel::table! {
     precomputed_reels (id) {
         id -> Integer,
@@ -392,6 +419,9 @@ diesel::allow_tables_to_appear_in_same_query!(
     personas,
     persons,
     photo_insights,
+    photo_version_display,
+    photo_version_references,
+    photo_versions,
     precomputed_reels,
     search_history,
     tagged_photo,