Store events and config in SQLite

Replace the JSON-file event and config stores with a SQLite database
(modernc.org/sqlite, pure-Go so the static build keeps CGO_ENABLED=0).
Last-write-wins now rides on the upsert's WHERE clause rather than a
Go-side map compare; the sync protocol and HTTP handlers are unchanged.

On first start the server auto-imports any legacy events.json/config.json
sitting in the data dir, renaming them to *.imported. The -data flag now
points at puppy.db; photos still live on the filesystem alongside it.

README.md

@@ -15,6 +15,10 @@ source-of-truth and sync between devices.
   client POSTs its full event list to `/api/events/sync`. The server merges
   it with its own copy using last-write-wins on `updatedAt` and returns the
   merged set.
+- The server keeps its copy in a SQLite database (`puppy.db`); events and the
+  shared profile are separate tables, and last-write-wins is enforced by the
+  upsert itself. On first start it auto-imports any legacy `events.json` /
+  `config.json` sitting alongside it, renaming them to `*.imported`.
 - Service worker bypasses cache for `/api/*` so writes always hit the server
   when online; static assets are still cached for offline use.
 - The puppy's name and birthday are a shared profile stored on the host
@@ -35,7 +39,8 @@ puppy-tracker/
 ├── module.nix        # systemd unit, StateDirectory, hardening
 ├── server/
 │   ├── go.mod
-│   └── main.go       # JSON-file store, LWW sync, static file serving
+│   ├── go.sum
+│   └── main.go       # SQLite store, LWW sync, static file serving
 └── src/              # the web app
     ├── index.html
     ├── app.js
@@ -52,7 +57,7 @@ nix run                       # http://localhost:8080, data in $XDG_DATA_HOME/pu
 PUPPY_ADDR=:9000 nix run      # custom port
 
 # Hot-iterate (data in /tmp):
-nix develop -c sh -c 'cd server && go run . -static ../src -data /tmp/puppy-events.json'
+nix develop -c sh -c 'cd server && go run . -static ../src -data /tmp/puppy.db'
 ```
 
 ## Use it on NixOS
@@ -81,8 +86,9 @@ In your system flake:
 }
 ```
 
-The server runs as a `DynamicUser` systemd unit. Data is stored at
+The server runs as a `DynamicUser` systemd unit. Data is stored in a SQLite
-`/var/lib/puppy-tracker/events.json` via `StateDirectory`.
+database at `/var/lib/puppy-tracker/puppy.db` via `StateDirectory` (with photos
+alongside it under `photos/`).
 
 ## Notes
 

flake.nix

@@ -26,7 +26,7 @@
           pname = "puppy-tracker-server";
           version = "0.2.0";
           src = ./server;
-          vendorHash = null; # no external dependencies
+          vendorHash = "sha256-fqXpr9fV1jeT7503uAjb4jjNPlXfESFnXr7/Uc83d4o=";
           # Pure-Go build for a tiny static binary.
           env.CGO_ENABLED = "0";
           ldflags = [ "-s" "-w" ];
@@ -76,7 +76,7 @@
             exec ${server}/bin/puppy-tracker-server \
               -addr "''${PUPPY_ADDR:-:8080}" \
               -static ${static}/share/puppy-tracker \
-              -data "$data_dir/events.json"
+              -data "$data_dir/puppy.db"
           '');
           meta.description = "Run puppy-tracker locally (data in $XDG_DATA_HOME/puppy-tracker)";
         };

module.nix

@@ -53,7 +53,7 @@ in
           "${cfg.package}/bin/puppy-tracker-server"
           "-addr ${cfg.address}:${toString cfg.port}"
           "-static ${cfg.staticPackage}/share/puppy-tracker"
-          "-data /var/lib/puppy-tracker/events.json"
+          "-data /var/lib/puppy-tracker/puppy.db"
         ];
 
         DynamicUser = true;

server/go.mod

@@ -1,3 +1,17 @@
 module puppy-tracker
 
-go 1.22
+go 1.25.0
+
+require modernc.org/sqlite v1.53.0
+
+require (
+	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/ncruces/go-strftime v1.0.0 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	golang.org/x/sys v0.44.0 // indirect
+	modernc.org/libc v1.73.4 // indirect
+	modernc.org/mathutil v1.7.1 // indirect
+	modernc.org/memory v1.11.0 // indirect
+)

server/go.sum

@@ -0,0 +1,51 @@
+github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
+github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
+github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e h1:ijClszYn+mADRFY17kjQEVQ1XRhq2/JR1M3sGqeJoxs=
+github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e/go.mod h1:boTsfXsheKC2y+lKOCMpSfarhxDeIzfZG1jqGcPl3cA=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/hashicorp/golang-lru/v2 v2.0.7 h1:a+bsQ5rvGLjzHuww6tVxozPZFVghXaHOwFs4luLUK2k=
+github.com/hashicorp/golang-lru/v2 v2.0.7/go.mod h1:QeFd9opnmA6QUJc5vARoKUSoFhyfM2/ZepoAG6RGpeM=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/ncruces/go-strftime v1.0.0 h1:HMFp8mLCTPp341M/ZnA4qaf7ZlsbTc+miZjCLOFAw7w=
+github.com/ncruces/go-strftime v1.0.0/go.mod h1:Fwc5htZGVVkseilnfgOVb9mKy6w1naJmn9CehxcKcls=
+github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec h1:W09IVJc94icq4NjY3clb7Lk8O1qJ8BdBEF8z0ibU0rE=
+github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
+golang.org/x/mod v0.36.0 h1:JJjpVx6myfUsUdAzZuOSTTmRE0PfZeNWzzvKrP7amb4=
+golang.org/x/mod v0.36.0/go.mod h1:moc6ELqsWcOw5Ef3xVprK5ul/MvtVvkIXLziUOICjUQ=
+golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
+golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.44.0 h1:ildZl3J4uzeKP07r2F++Op7E9B29JRUy+a27EibtBTQ=
+golang.org/x/sys v0.44.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+golang.org/x/tools v0.45.0 h1:18qN3FAooORvApf5XjCXgsuayZOEtXf6JK18I3+ONa8=
+golang.org/x/tools v0.45.0/go.mod h1:LuUGqqaXcXMEFEruIVJVm5mgDD8vww/z/SR1gQ4uE/0=
+modernc.org/cc/v4 v4.28.4 h1:Hd/4Es+MBj+/7hSdZaisNyu6bv3V0Dp2MdllyfqaH+c=
+modernc.org/cc/v4 v4.28.4/go.mod h1:OnovgIhbbMXMu1aISnJ0wvVD1KnW+cAUJkIrAWh+kVI=
+modernc.org/ccgo/v4 v4.34.4 h1:OVnSOWQjVKOYkFxoHYB+qQmSHK5gqMqARM+K9DpR/Ws=
+modernc.org/ccgo/v4 v4.34.4/go.mod h1:qdKqE8FNIYyysougB1RX9MxCzp5oJOcQXSobANJ4TuE=
+modernc.org/fileutil v1.4.0 h1:j6ZzNTftVS054gi281TyLjHPp6CPHr2KCxEXjEbD6SM=
+modernc.org/fileutil v1.4.0/go.mod h1:EqdKFDxiByqxLk8ozOxObDSfcVOv/54xDs/DUHdvCUU=
+modernc.org/gc/v2 v2.6.5 h1:nyqdV8q46KvTpZlsw66kWqwXRHdjIlJOhG6kxiV/9xI=
+modernc.org/gc/v2 v2.6.5/go.mod h1:YgIahr1ypgfe7chRuJi2gD7DBQiKSLMPgBQe9oIiito=
+modernc.org/gc/v3 v3.1.3 h1:6QAplYyVO+KdPW3pGnqmJDUxtkec8ooEWvks/hhU3lc=
+modernc.org/gc/v3 v3.1.3/go.mod h1:HFK/6AGESC7Ex+EZJhJ2Gni6cTaYpSMmU/cT9RmlfYY=
+modernc.org/goabi0 v0.2.0 h1:HvEowk7LxcPd0eq6mVOAEMai46V+i7Jrj13t4AzuNks=
+modernc.org/goabi0 v0.2.0/go.mod h1:CEFRnnJhKvWT1c1JTI3Avm+tgOWbkOu5oPA8eH8LnMI=
+modernc.org/libc v1.73.4 h1:+ra4Ui8ngyt8HDcO1FTDPWlkAh6yOdaO2yAoh8MddQA=
+modernc.org/libc v1.73.4/go.mod h1:DXZ3eO8qMCNn2SnmTNCiC71nJ9Rcq3PsnpU6Vc4rWK8=
+modernc.org/mathutil v1.7.1 h1:GCZVGXdaN8gTqB1Mf/usp1Y/hSqgI2vAGGP4jZMCxOU=
+modernc.org/mathutil v1.7.1/go.mod h1:4p5IwJITfppl0G4sUEDtCr4DthTaT47/N3aT6MhfgJg=
+modernc.org/memory v1.11.0 h1:o4QC8aMQzmcwCK3t3Ux/ZHmwFPzE6hf2Y5LbkRs+hbI=
+modernc.org/memory v1.11.0/go.mod h1:/JP4VbVC+K5sU2wZi9bHoq2MAkCnrt2r98UGeSK7Mjw=
+modernc.org/opt v0.2.0 h1:tGyef5ApycA7FSEOMraay9SaTk5zmbx7Tu+cJs4QKZg=
+modernc.org/opt v0.2.0/go.mod h1:03fq9lsNfvkYSfxrfUhZCWPk1lm4cq4N+Bh//bEtgns=
+modernc.org/sortutil v1.2.1 h1:+xyoGf15mM3NMlPDnFqrteY07klSFxLElE2PVuWIJ7w=
+modernc.org/sortutil v1.2.1/go.mod h1:7ZI3a3REbai7gzCLcotuw9AC4VZVpYMjDzETGsSMqJE=
+modernc.org/sqlite v1.53.0 h1:20WG8N9q4ji/dEqGk4uiI0c6OPjSeLTNYGFCc3+7c1M=
+modernc.org/sqlite v1.53.0/go.mod h1:xoEpOIpGrgT48H5iiyt/YXPCZPEzlfmfFwtk8Lklw8s=
+modernc.org/strutil v1.2.1 h1:UneZBkQA+DX2Rp35KcM69cSsNES9ly8mQWD71HKlOA0=
+modernc.org/strutil v1.2.1/go.mod h1:EHkiggD70koQxjVdSBM3JKM7k6L0FbGE5eymy9i3B9A=
+modernc.org/token v1.1.0 h1:Xl7Ap9dKaEs5kLoOQeQmPWevfnk/DM5qcLcYlA8ys6Y=
+modernc.org/token v1.1.0/go.mod h1:UGzOrNV1mAFSEB63lOFHIpNRUVMvYTc6yu1SMY/XTDM=

server/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"database/sql"
 	"encoding/json"
 	"errors"
 	"flag"
@@ -12,8 +13,9 @@ import (
 	"path/filepath"
 	"regexp"
 	"strings"
-	"sync"
 	"time"
+
+	_ "modernc.org/sqlite"
 )
 
 type Event struct {
@@ -45,155 +47,230 @@ type Config struct {
 }
 
 type ConfigStore struct {
-	path string
+	db *sql.DB
-	mu   sync.Mutex
-	cfg  Config
 }
 
-func newConfigStore(path string) (*ConfigStore, error) {
+func newConfigStore(db *sql.DB) *ConfigStore {
-	cs := &ConfigStore{path: path}
+	return &ConfigStore{db: db}
-	f, err := os.Open(path)
-	if err != nil {
-		if errors.Is(err, fs.ErrNotExist) {
-			return cs, nil
-		}
-		return nil, err
-	}
-	defer f.Close()
-	if err := json.NewDecoder(f).Decode(&cs.cfg); err != nil && !errors.Is(err, io.EOF) {
-		return nil, err
-	}
-	return cs, nil
 }
 
 func (cs *ConfigStore) get() Config {
-	cs.mu.Lock()
+	var c Config
-	defer cs.mu.Unlock()
+	// The profile lives in a single row (id = 1). A missing row is the
-	return cs.cfg
+	// pre-configuration state, so a zero-value Config is the right answer.
+	err := cs.db.QueryRow(
+		`SELECT name, birthday, updated FROM config WHERE id = 1`,
+	).Scan(&c.Name, &c.Birthday, &c.UpdatedAt)
+	if err != nil && !errors.Is(err, sql.ErrNoRows) {
+		log.Printf("config get: %v", err)
+	}
+	return c
 }
 
 // merge applies an incoming config with last-write-wins by UpdatedAt and
 // returns the resulting stored config (which the caller sends back).
 func (cs *ConfigStore) merge(in Config) (Config, error) {
-	cs.mu.Lock()
+	// The upsert's WHERE clause enforces last-write-wins: the incoming row only
-	defer cs.mu.Unlock()
+	// replaces the stored one when it is strictly newer.
-	if in.UpdatedAt > cs.cfg.UpdatedAt {
+	_, err := cs.db.Exec(`
-		cs.cfg = in
+		INSERT INTO config (id, name, birthday, updated)
-		if err := cs.saveLocked(); err != nil {
+		VALUES (1, ?, ?, ?)
-			return cs.cfg, err
+		ON CONFLICT(id) DO UPDATE SET
-		}
+			name = excluded.name, birthday = excluded.birthday, updated = excluded.updated
-	}
+		WHERE excluded.updated > config.updated`,
-	return cs.cfg, nil
+		in.Name, in.Birthday, in.UpdatedAt)
-}
-
-// Caller must hold cs.mu.
-func (cs *ConfigStore) saveLocked() error {
-	if err := os.MkdirAll(filepath.Dir(cs.path), 0o755); err != nil {
-		return err
-	}
-	tmp := cs.path + ".tmp"
-	f, err := os.Create(tmp)
 	if err != nil {
-		return err
+		return Config{}, err
 	}
-	enc := json.NewEncoder(f)
+	return cs.get(), nil
-	enc.SetIndent("", "  ")
-	if err := enc.Encode(cs.cfg); err != nil {
-		f.Close()
-		os.Remove(tmp)
-		return err
-	}
-	if err := f.Close(); err != nil {
-		return err
-	}
-	return os.Rename(tmp, cs.path)
 }
 
 type Store struct {
-	path string
+	db *sql.DB
-	mu   sync.Mutex
-	data map[string]Event
 }
 
-func newStore(path string) (*Store, error) {
+func newStore(db *sql.DB) *Store {
-	s := &Store{path: path, data: map[string]Event{}}
+	return &Store{db: db}
-	if err := s.load(); err != nil {
+}
+
+// sync merges client events into the store using last-write-wins by UpdatedAt,
+// then returns the full merged set (including tombstones, which must propagate).
+func (s *Store) sync(client []Event) ([]Event, error) {
+	tx, err := s.db.Begin()
+	if err != nil {
 		return nil, err
 	}
-	return s, nil
+	defer tx.Rollback()
+
+	// The WHERE clause on the upsert is the last-write-wins rule: an incoming
+	// event only overwrites the stored one when its updatedAt is strictly newer.
+	stmt, err := tx.Prepare(`
+		INSERT INTO events (id, type, at, note, photo_id, weight, updated, deleted)
+		VALUES (?, ?, ?, ?, ?, ?, ?, ?)
+		ON CONFLICT(id) DO UPDATE SET
+			type = excluded.type, at = excluded.at, note = excluded.note,
+			photo_id = excluded.photo_id, weight = excluded.weight,
+			updated = excluded.updated, deleted = excluded.deleted
+		WHERE excluded.updated > events.updated`)
+	if err != nil {
+		return nil, err
+	}
+	defer stmt.Close()
+
+	for _, ce := range client {
+		if ce.ID == "" {
+			continue
+		}
+		if _, err := stmt.Exec(
+			ce.ID, ce.Type, ce.At, ce.Note, ce.PhotoID, ce.Weight, ce.UpdatedAt, ce.Deleted,
+		); err != nil {
+			return nil, err
+		}
+	}
+	if err := tx.Commit(); err != nil {
+		return nil, err
+	}
+	return s.all()
 }
 
-func (s *Store) load() error {
+// all returns every stored event, tombstones included.
-	f, err := os.Open(s.path)
+func (s *Store) all() ([]Event, error) {
+	rows, err := s.db.Query(
+		`SELECT id, type, at, note, photo_id, weight, updated, deleted FROM events`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	out := make([]Event, 0)
+	for rows.Next() {
+		var e Event
+		if err := rows.Scan(
+			&e.ID, &e.Type, &e.At, &e.Note, &e.PhotoID, &e.Weight, &e.UpdatedAt, &e.Deleted,
+		); err != nil {
+			return nil, err
+		}
+		out = append(out, e)
+	}
+	return out, rows.Err()
+}
+
+// openDB opens (creating if needed) the SQLite database and ensures the schema
+// exists. WAL mode plays nicely with concurrent readers during a sync write;
+// busy_timeout avoids spurious "database is locked" errors under contention.
+func openDB(path string) (*sql.DB, error) {
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return nil, err
+	}
+	db, err := sql.Open("sqlite", path)
+	if err != nil {
+		return nil, err
+	}
+	for _, pragma := range []string{
+		`PRAGMA journal_mode = WAL`,
+		`PRAGMA busy_timeout = 5000`,
+		`PRAGMA synchronous = NORMAL`,
+	} {
+		if _, err := db.Exec(pragma); err != nil {
+			db.Close()
+			return nil, err
+		}
+	}
+	schema := `
+		CREATE TABLE IF NOT EXISTS events (
+			id       TEXT PRIMARY KEY,
+			type     TEXT NOT NULL DEFAULT '',
+			at       INTEGER NOT NULL DEFAULT 0,
+			note     TEXT NOT NULL DEFAULT '',
+			photo_id TEXT NOT NULL DEFAULT '',
+			weight   REAL NOT NULL DEFAULT 0,
+			updated  INTEGER NOT NULL DEFAULT 0,
+			deleted  INTEGER NOT NULL DEFAULT 0
+		);
+		CREATE TABLE IF NOT EXISTS config (
+			id       INTEGER PRIMARY KEY CHECK (id = 1),
+			name     TEXT NOT NULL DEFAULT '',
+			birthday TEXT NOT NULL DEFAULT '',
+			updated  INTEGER NOT NULL DEFAULT 0
+		);`
+	if _, err := db.Exec(schema); err != nil {
+		db.Close()
+		return nil, err
+	}
+	return db, nil
+}
+
+// migrateJSON imports a pre-SQLite events.json / config.json sitting in dataDir
+// into an otherwise-empty database, then renames each file to *.imported so the
+// import runs exactly once. It is a no-op when the DB already holds data or the
+// legacy files are absent.
+func migrateJSON(db *sql.DB, dataDir string) error {
+	if err := importEvents(db, filepath.Join(dataDir, "events.json")); err != nil {
+		return err
+	}
+	return importConfig(db, filepath.Join(dataDir, "config.json"))
+}
+
+func importEvents(db *sql.DB, path string) error {
+	var n int
+	if err := db.QueryRow(`SELECT COUNT(*) FROM events`).Scan(&n); err != nil {
+		return err
+	}
+	if n > 0 {
+		return nil // DB already has data; never clobber it
+	}
+	f, err := os.Open(path)
 	if err != nil {
 		if errors.Is(err, fs.ErrNotExist) {
 			return nil
 		}
 		return err
 	}
-	defer f.Close()
 	var evs []Event
-	if err := json.NewDecoder(f).Decode(&evs); err != nil {
+	dec := json.NewDecoder(f)
-		if errors.Is(err, io.EOF) {
+	err = dec.Decode(&evs)
-			return nil
-		}
-		return err
-	}
-	for _, e := range evs {
-		s.data[e.ID] = e
-	}
-	return nil
-}
-
-// Caller must hold s.mu.
-func (s *Store) saveLocked() error {
-	if err := os.MkdirAll(filepath.Dir(s.path), 0o755); err != nil {
-		return err
-	}
-	tmp := s.path + ".tmp"
-	f, err := os.Create(tmp)
-	if err != nil {
-		return err
-	}
-	evs := make([]Event, 0, len(s.data))
-	for _, e := range s.data {
-		evs = append(evs, e)
-	}
-	enc := json.NewEncoder(f)
-	enc.SetIndent("", "  ")
-	if err := enc.Encode(evs); err != nil {
 	f.Close()
-		os.Remove(tmp)
+	if err != nil && !errors.Is(err, io.EOF) {
 		return err
 	}
-	if err := f.Close(); err != nil {
+	store := newStore(db)
+	if _, err := store.sync(evs); err != nil {
 		return err
 	}
-	return os.Rename(tmp, s.path)
+	log.Printf("migrated %d events from %s", len(evs), path)
+	return os.Rename(path, path+".imported")
 }
 
-// sync merges client events into the store using last-write-wins by UpdatedAt,
+func importConfig(db *sql.DB, path string) error {
-// then returns the full merged set.
+	var n int
-func (s *Store) sync(client []Event) ([]Event, error) {
+	if err := db.QueryRow(`SELECT COUNT(*) FROM config`).Scan(&n); err != nil {
-	s.mu.Lock()
+		return err
-	defer s.mu.Unlock()
-	for _, ce := range client {
-		if ce.ID == "" {
-			continue
 	}
-		existing, ok := s.data[ce.ID]
+	if n > 0 {
-		if !ok || ce.UpdatedAt > existing.UpdatedAt {
+		return nil
-			s.data[ce.ID] = ce
 	}
+	f, err := os.Open(path)
+	if err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
+			return nil
 		}
-	if err := s.saveLocked(); err != nil {
+		return err
-		return nil, err
 	}
-	out := make([]Event, 0, len(s.data))
+	var c Config
-	for _, e := range s.data {
+	dec := json.NewDecoder(f)
-		out = append(out, e)
+	err = dec.Decode(&c)
+	f.Close()
+	if err != nil && !errors.Is(err, io.EOF) {
+		return err
 	}
-	return out, nil
+	if c.UpdatedAt == 0 {
+		// Nothing meaningful to import; leave config empty.
+		return os.Rename(path, path+".imported")
+	}
+	if _, err := newConfigStore(db).merge(c); err != nil {
+		return err
+	}
+	log.Printf("migrated config from %s", path)
+	return os.Rename(path, path+".imported")
 }
 
 type syncRequest struct {
@@ -213,19 +290,23 @@ func (c cacheControlFS) Open(name string) (http.File, error) { return c.root.Ope
 
 func main() {
 	addr := flag.String("addr", ":8080", "listen address (e.g. :8080 or 0.0.0.0:8080)")
-	dataPath := flag.String("data", "events.json", "path to events JSON file")
+	dataPath := flag.String("data", "puppy.db", "path to SQLite database file")
 	staticDir := flag.String("static", "", "directory of static files to serve")
 	flag.Parse()
 
-	store, err := newStore(*dataPath)
+	db, err := openDB(*dataPath)
 	if err != nil {
-		log.Fatalf("load store: %v", err)
+		log.Fatalf("open db: %v", err)
+	}
+	defer db.Close()
+
+	// One-time import of any pre-SQLite JSON data sitting next to the DB.
+	if err := migrateJSON(db, filepath.Dir(*dataPath)); err != nil {
+		log.Fatalf("migrate json: %v", err)
 	}
 
-	configStore, err := newConfigStore(filepath.Join(filepath.Dir(*dataPath), "config.json"))
+	store := newStore(db)
-	if err != nil {
+	configStore := newConfigStore(db)
-		log.Fatalf("load config: %v", err)
-	}
 
 	photosDir := filepath.Join(filepath.Dir(*dataPath), "photos")
 	if err := os.MkdirAll(photosDir, 0o755); err != nil {