feat: add initial types/logic to observe SQLite

- We need a clean and reliable way to know when a SQLite
  database has been updated (written to). SQLite provides
  hooks which describe changes that have been committed
  - Which table
  - Which rowid
  - Old and new values when applicable
- Phase 1 includes:
  - The hooks part of the library which is the code that
  communicates with the SQLite C ABI. We register for:
    - Preupdate hook
    - Commit hook (fires for implicit and explicit tx commits
    - Rollback hook
  - The `TableChange` and `ColumnValue` types
  and helpers
  - The broker API which takes subscriptions and manages
  the buffer of change events
  - Details about what's to come in the next two phases,
  in the README
- Use of this feature requires that we bundle a version of
  SQLite which supports these hooks, which we planned
  to do anyway.

Author: pmorris-dev

Cargo.lock

@@ -2,6 +2,7 @@
 resolver = "3"
 members = [
    "crates/sqlx-sqlite-conn-mgr",
+   "crates/sqlx-sqlite-observer",
 ]
 
 [package]

Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "sqlx-sqlite-observer"
+# Sync major.minor with major.minor of SQLx crate
+version = "0.8.6"
+license = "MIT"
+edition = "2024"
+rust-version = "1.89"
+authors = ["Jeremy Thomerson"]
+description = "Reactive change notifications for SQLite databases using sqlx"
+repository = "https://github.com/silvermine/tauri-plugin-sqlite"
+readme = "README.md"
+keywords = ["sqlite", "sqlx", "reactive", "observer", "database"]
+categories = ["database", "asynchronous"]
+
+[features]
+# Bundle SQLite by default - preupdate hooks require SQLITE_ENABLE_PREUPDATE_HOOK
+# which most system SQLite libraries don't have enabled.
+default = ["bundled"]
+bundled = ["libsqlite3-sys/bundled"]
+
+[dependencies]
+tokio = { version = "1.49.0", features = ["sync"] }
+thiserror = "2.0.17"
+tracing = { version = "0.1.44", default-features = false, features = ["std", "release_max_level_off"] }
+parking_lot = "0.12.3"
+# Required for preupdate_hook - SQLite must be compiled with SQLITE_ENABLE_PREUPDATE_HOOK
+libsqlite3-sys = { version = "0.30", features = ["preupdate_hook"] }
+
+[dev-dependencies]
+tokio = { version = "1.49.0", features = ["full", "macros"] }

crates/sqlx-sqlite-observer/Cargo.toml

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Jeremy Thomerson
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.