feat: add persistent CPU search engine and CLI with lifecycle tests

crates/searchi-core/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "searchi-core"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+anyhow.workspace = true
+serde.workspace = true
+rusqlite = { version = "0.32", features = ["bundled"] }
+walkdir = "2"
+
+[dev-dependencies]
+tempfile = "3"

crates/searchi-core/README.md

@@ -0,0 +1,49 @@
+# Searchi core
+
+The core has no desktop or inference dependencies. Its current retrieval engine
+combines literal filename matching with SQLite FTS5 BM25 keyword search. It does
+not implement semantic search.
+
+`SearchIndex::open` creates or migrates schema version 2. Current-schema opens do
+not acquire a write lock. WAL allows independent readers to use the committed
+index while reconciliation runs. All indexing changes are committed atomically;
+a traversal or supported-file read error rolls back the entire reconciliation.
+
+`index_folder` applies `IndexOptions::default()`: directories named `.git`,
+`node_modules`, and `target` are pruned. `index_folder_with_options` lets callers
+replace those names. Matching directory names are ASCII case insensitive. An
+explicit root is always traversed, even if its name is excluded. Symlinks are not
+followed. The index's own database, WAL, and shared-memory files are excluded.
+
+Metadata includes byte size and modification time at nanosecond resolution.
+Unchanged files bypass extraction. `IndexReport.indexed` counts newly extracted
+or updated records; `unchanged` counts reused records; `skipped` counts new or
+changed records whose content could not be extracted because of format, encoding,
+or size. Unsupported files remain searchable by filename. Content reads are
+limited to 2 MiB. Reconciliation tracks seen files in SQLite rather than retaining
+every path in process memory.
+
+`search_with_options` supports canonical folder boundaries, extension, inclusive
+size bounds, and inclusive Unix millisecond modification-time bounds. Filters
+apply before limiting results. `search` retains the unfiltered API. Query text is
+escaped as literal FTS terms, not interpreted as operators. Results are capped at
+1,000 and queries at 4,096 bytes.
+
+## Known limits
+
+- Filename substring lookup uses `instr` and scans metadata. A dedicated substring
+  index and benchmarks are needed before claiming million-file latency targets.
+- Files changed without changing size or modification time require a future
+  forced refresh/content-fingerprint option. Timestamp precision depends on the
+  filesystem. Indexing does not yet run a filesystem watcher.
+- Metadata modification times before the Unix epoch or beyond the nanosecond
+  integer range are explicit errors. Unicode filename case folding is currently
+  limited by SQLite's built-in `lower` function.
+- Lossy path conversion does not preserve non-Unicode native filenames. This must
+  be addressed before Linux production support for arbitrary byte filenames.
+- The `files.root` ownership model does not yet support overlapping selected
+  roots independently. Use disjoint roots until root memberships are implemented.
+- Extraction runs in the caller and a large reconciliation holds one transaction.
+  Bounded worker isolation, persistent jobs, and crash-resumable scans remain
+  production milestones.
+- PDF, DOCX, OCR, media extraction, and real model inference remain unimplemented.

crates/searchi-core/src/lib.rs

@@ -0,0 +1,482 @@
+//! Offline lexical search engine shared by the CLI and desktop shell.
+//!
+//! Reconciliation is atomic. Incomplete directory walks never delete records.
+//! Text extraction is deliberately bounded; binary document extractors belong in
+//! isolated workers in the next milestone, not in this indexing transaction.
+use anyhow::{bail, Context, Result};
+use rusqlite::{params, Connection, OptionalExtension};
+use serde::Serialize;
+use std::{
+    fs,
+    io::Read,
+    path::{Path, PathBuf},
+    time::UNIX_EPOCH,
+};
+use walkdir::WalkDir;
+
+const SCHEMA_VERSION: i64 = 2;
+const MAX_TEXT_BYTES: u64 = 2 * 1024 * 1024;
+const MAX_RESULTS: usize = 1000;
+
+#[derive(Debug, Default, Serialize)]
+pub struct IndexReport {
+    pub discovered: usize,
+    pub indexed: usize,
+    pub removed: usize,
+    pub skipped: usize,
+    pub unchanged: usize,
+}
+
+/// Names of directories to prune anywhere below an explicitly chosen root.
+#[derive(Debug, Clone)]
+pub struct IndexOptions {
+    pub excluded_directory_names: Vec<String>,
+}
+
+impl Default for IndexOptions {
+    fn default() -> Self {
+        Self {
+            excluded_directory_names: vec![".git".into(), "node_modules".into(), "target".into()],
+        }
+    }
+}
+
+/// Filters are independent of query syntax and apply before the result limit.
+/// The folder is canonicalized and includes descendants, with a path-boundary check.
+#[derive(Debug, Default, Clone)]
+pub struct SearchOptions {
+    pub folder: Option<PathBuf>,
+    pub extension: Option<String>,
+    pub min_size: Option<u64>,
+    pub max_size: Option<u64>,
+    pub modified_after_unix_ms: Option<i64>,
+    pub modified_before_unix_ms: Option<i64>,
+}
+
+#[derive(Debug, Serialize)]
+pub struct SearchResult {
+    pub path: String,
+    pub filename: String,
+    pub snippet: String,
+    pub score: f64,
+    pub match_kind: String,
+}
+
+#[derive(Debug, Serialize)]
+pub struct IndexStats {
+    pub files: usize,
+    pub content_files: usize,
+}
+
+pub struct SearchIndex {
+    connection: Connection,
+    database_path: Option<PathBuf>,
+}
+
+impl SearchIndex {
+    pub fn open(path: impl AsRef<Path>) -> Result<Self> {
+        let path = path.as_ref();
+        let mut connection = Connection::open(path).context("open search database")?;
+        let database_path = if path == Path::new(":memory:") {
+            None
+        } else {
+            Some(fs::canonicalize(path).context("resolve database path")?)
+        };
+        connection.busy_timeout(std::time::Duration::from_secs(5))?;
+        let version: i64 = connection.query_row("PRAGMA user_version", [], |row| row.get(0))?;
+        if !(0..=SCHEMA_VERSION).contains(&version) {
+            bail!("unsupported database version {version}; expected {SCHEMA_VERSION}");
+        }
+        if version != SCHEMA_VERSION {
+            connection.execute_batch("PRAGMA journal_mode=WAL;")?;
+            let initialization =
+                connection.transaction_with_behavior(rusqlite::TransactionBehavior::Immediate)?;
+            // Another opener may have completed initialization while we waited.
+            let version: i64 =
+                initialization.query_row("PRAGMA user_version", [], |row| row.get(0))?;
+            if !(0..=SCHEMA_VERSION).contains(&version) {
+                bail!("unsupported database version {version}");
+            }
+            initialization.execute_batch(
+                "
+            CREATE TABLE IF NOT EXISTS files (
+                id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE,
+                root TEXT NOT NULL, filename TEXT NOT NULL, content TEXT NOT NULL,
+                size INTEGER NOT NULL DEFAULT -1, mtime INTEGER NOT NULL DEFAULT -1,
+                extension TEXT NOT NULL DEFAULT '');
+            CREATE INDEX IF NOT EXISTS files_root ON files(root);
+            CREATE VIRTUAL TABLE IF NOT EXISTS search USING fts5(filename, path, content,
+                content='files', content_rowid='id', tokenize='unicode61');
+            CREATE TRIGGER IF NOT EXISTS files_insert AFTER INSERT ON files BEGIN
+                INSERT INTO search(rowid, filename, path, content)
+                VALUES (new.id, new.filename, new.path, new.content); END;
+            CREATE TRIGGER IF NOT EXISTS files_delete AFTER DELETE ON files BEGIN
+                INSERT INTO search(search, rowid, filename, path, content)
+                VALUES ('delete', old.id, old.filename, old.path, old.content); END;
+            CREATE TRIGGER IF NOT EXISTS files_update AFTER UPDATE ON files BEGIN
+                INSERT INTO search(search, rowid, filename, path, content)
+                VALUES ('delete', old.id, old.filename, old.path, old.content);
+                INSERT INTO search(rowid, filename, path, content)
+                VALUES (new.id, new.filename, new.path, new.content); END;
+            ",
+            )?;
+            if version == 1 {
+                initialization.execute_batch(
+                    "
+                ALTER TABLE files ADD COLUMN size INTEGER NOT NULL DEFAULT -1;
+                ALTER TABLE files ADD COLUMN mtime INTEGER NOT NULL DEFAULT -1;
+                ALTER TABLE files ADD COLUMN extension TEXT NOT NULL DEFAULT '';
+                PRAGMA user_version=2;",
+                )?;
+            } else {
+                initialization.execute_batch("PRAGMA user_version=2;")?;
+            }
+            initialization.commit()?;
+        }
+        Ok(Self {
+            connection,
+            database_path,
+        })
+    }
+
+    /// Reconcile one explicitly selected root. Symlinks are never followed.
+    /// Every file receives a filename record, including unsupported formats.
+    pub fn index_folder(&mut self, root: impl AsRef<Path>) -> Result<IndexReport> {
+        self.index_folder_with_options(root, &IndexOptions::default())
+    }
+
+    pub fn index_folder_with_options(
+        &mut self,
+        root: impl AsRef<Path>,
+        options: &IndexOptions,
+    ) -> Result<IndexReport> {
+        let root = fs::canonicalize(root).context("resolve index root")?;
+        if !root.is_dir() {
+            bail!("index root must be a directory");
+        }
+        let root_key = root.to_string_lossy().into_owned();
+        let transaction = self.connection.transaction()?;
+        transaction.execute_batch(
+            "CREATE TEMP TABLE IF NOT EXISTS seen_paths(path TEXT PRIMARY KEY);
+            DELETE FROM seen_paths;",
+        )?;
+        let mut report = IndexReport::default();
+        for entry in WalkDir::new(&root)
+            .follow_links(false)
+            .into_iter()
+            .filter_entry(|entry| {
+                entry.depth() == 0
+                    || !entry.file_type().is_dir()
+                    || !options.excluded_directory_names.iter().any(|name| {
+                        entry
+                            .file_name()
+                            .to_string_lossy()
+                            .eq_ignore_ascii_case(name)
+                    })
+            })
+        {
+            let entry = entry.context("directory traversal failed; reconciliation rolled back")?;
+            if !entry.file_type().is_file() {
+                continue;
+            }
+            if let Some(database) = &self.database_path {
+                let path_key = entry.path().to_string_lossy();
+                let db_key = database.to_string_lossy();
+                if path_key == db_key
+                    || path_key == format!("{db_key}-wal")
+                    || path_key == format!("{db_key}-shm")
+                {
+                    continue;
+                }
+            }
+            let path = entry.path().to_string_lossy().into_owned();
+            let filename = entry.file_name().to_string_lossy().into_owned();
+            transaction.execute("INSERT INTO seen_paths(path) VALUES (?1)", [&path])?;
+            report.discovered += 1;
+            let metadata = entry.metadata()?;
+            let size = i64::try_from(metadata.len()).context("file exceeds supported size")?;
+            let modified = metadata
+                .modified()?
+                .duration_since(UNIX_EPOCH)
+                .context("file timestamp predates Unix epoch")?;
+            let mtime = i64::try_from(modified.as_nanos())
+                .context("file timestamp exceeds supported range")?;
+            let extension = entry
+                .path()
+                .extension()
+                .and_then(|value| value.to_str())
+                .unwrap_or("")
+                .to_ascii_lowercase();
+            let previous: Option<(i64, i64, String)> = transaction
+                .query_row(
+                    "SELECT size,mtime,root FROM files WHERE path=?1",
+                    [&path],
+                    |row| Ok((row.get(0)?, row.get(1)?, row.get(2)?)),
+                )
+                .optional()?;
+            if previous == Some((size, mtime, root_key.clone())) {
+                report.unchanged += 1;
+                continue;
+            }
+            let content = extract_text(entry.path()).with_context(|| format!("read {path}"))?;
+            if content.is_none() {
+                report.skipped += 1;
+            }
+            transaction.execute(
+                "INSERT INTO files(path,root,filename,content,size,mtime,extension) VALUES (?1,?2,?3,?4,?5,?6,?7)
+                ON CONFLICT(path) DO UPDATE SET root=excluded.root, filename=excluded.filename,
+                content=excluded.content, size=excluded.size, mtime=excluded.mtime,
+                extension=excluded.extension",
+                params![path, root_key, filename, content.unwrap_or_default(), size, mtime, extension],
+            )?;
+            report.indexed += 1;
+        }
+        report.removed = transaction.execute(
+            "DELETE FROM files WHERE root=?1
+            AND NOT EXISTS (SELECT 1 FROM seen_paths WHERE seen_paths.path=files.path)",
+            [&root_key],
+        )?;
+        transaction.execute("DELETE FROM seen_paths", [])?;
+        transaction.commit()?;
+        Ok(report)
+    }
+
+    /// Literal input is escaped before FTS parsing; user text cannot inject operators.
+    /// Exact filenames precede partial filenames, which precede content matches.
+    /// Filename substring matching currently scans metadata; a dedicated substring
+    /// index is required before claiming million-file latency targets.
+    pub fn search(&self, query: &str, limit: usize) -> Result<Vec<SearchResult>> {
+        self.search_with_options(query, limit, &SearchOptions::default())
+    }
+
+    pub fn search_with_options(
+        &self,
+        query: &str,
+        limit: usize,
+        options: &SearchOptions,
+    ) -> Result<Vec<SearchResult>> {
+        if options
+            .min_size
+            .zip(options.max_size)
+            .is_some_and(|(min, max)| min > max)
+        {
+            bail!("minimum size exceeds maximum size");
+        }
+        if options
+            .modified_after_unix_ms
+            .zip(options.modified_before_unix_ms)
+            .is_some_and(|(min, max)| min > max)
+        {
+            bail!("modified-after exceeds modified-before");
+        }
+        let folder = options
+            .folder
+            .as_ref()
+            .map(fs::canonicalize)
+            .transpose()?
+            .map(|path| path.to_string_lossy().into_owned());
+        let folder_prefix = folder.as_ref().map(|value| {
+            format!(
+                "{}{}",
+                value.trim_end_matches(['/', '\\']),
+                std::path::MAIN_SEPARATOR
+            )
+        });
+        let extension = options
+            .extension
+            .as_ref()
+            .map(|value| value.trim_start_matches('.').to_ascii_lowercase());
+        let min_size = options
+            .min_size
+            .map(i64::try_from)
+            .transpose()
+            .context("minimum size exceeds supported range")?;
+        let max_size = options
+            .max_size
+            .map(i64::try_from)
+            .transpose()
+            .context("maximum size exceeds supported range")?;
+        let query = query.trim();
+        if query.is_empty() || limit == 0 {
+            return Ok(Vec::new());
+        }
+        if query.len() > 4096 {
+            bail!("query exceeds 4096 bytes");
+        }
+        let fts = query
+            .split_whitespace()
+            .map(|term| format!("\"{}\"", term.replace('"', "\"\"")))
+            .collect::<Vec<_>>()
+            .join(" AND ");
+        let mut statement = self.connection.prepare(
+            "WITH hits AS (
+            SELECT rowid AS id, bm25(search, 8.0, 2.0, 1.0) AS rank,
+                snippet(search, 2, '', '', ' … ', 24) AS excerpt
+            FROM search WHERE search MATCH ?1)
+            SELECT f.path, f.filename, COALESCE(h.excerpt, ''), COALESCE(h.rank, 0),
+                CASE WHEN lower(f.filename)=lower(?2) THEN 0
+                WHEN instr(lower(f.filename), lower(?2)) > 0 THEN 1 ELSE 2 END AS tier
+            FROM files f LEFT JOIN hits h ON h.id=f.id
+            WHERE (h.id IS NOT NULL OR instr(lower(f.filename), lower(?2)) > 0)
+            AND (?4 IS NULL OR substr(f.path,1,length(?4))=?4)
+            AND (?5 IS NULL OR f.extension=?5)
+            AND (?6 IS NULL OR f.size>=?6) AND (?7 IS NULL OR f.size<=?7)
+            AND (?8 IS NULL OR f.mtime/1000000>=?8) AND (?9 IS NULL OR f.mtime/1000000<=?9)
+            ORDER BY tier, h.rank, f.path LIMIT ?3",
+        )?;
+        let results = statement
+            .query_map(
+                params![
+                    fts,
+                    query,
+                    limit.min(MAX_RESULTS) as i64,
+                    folder_prefix,
+                    extension,
+                    min_size,
+                    max_size,
+                    options.modified_after_unix_ms,
+                    options.modified_before_unix_ms
+                ],
+                |row| {
+                    let tier: i64 = row.get(4)?;
+                    Ok(SearchResult {
+                        path: row.get(0)?,
+                        filename: row.get(1)?,
+                        snippet: row.get(2)?,
+                        score: -row.get::<_, f64>(3)?,
+                        match_kind: match tier {
+                            0 => "exact_filename",
+                            1 => "filename",
+                            _ => "content",
+                        }
+                        .to_owned(),
+                    })
+                },
+            )?
+            .collect::<rusqlite::Result<Vec<_>>>()?;
+        Ok(results)
+    }
+
+    pub fn stats(&self) -> Result<IndexStats> {
+        Ok(self.connection.query_row(
+            "SELECT count(*), count(NULLIF(content, '')) FROM files",
+            [],
+            |row| {
+                Ok(IndexStats {
+                    files: row.get(0)?,
+                    content_files: row.get(1)?,
+                })
+            },
+        )?)
+    }
+}
+
+fn extract_text(path: &Path) -> Result<Option<String>> {
+    let extension = path
+        .extension()
+        .and_then(|value| value.to_str())
+        .unwrap_or("")
+        .to_ascii_lowercase();
+    if !matches!(
+        extension.as_str(),
+        "txt"
+            | "md"
+            | "rs"
+            | "py"
+            | "js"
+            | "ts"
+            | "tsx"
+            | "jsx"
+            | "json"
+            | "toml"
+            | "yaml"
+            | "yml"
+            | "csv"
+            | "html"
+            | "css"
+            | "xml"
+            | "log"
+            | "sh"
+    ) {
+        return Ok(None);
+    }
+    let file = fs::File::open(path)?;
+    if file.metadata()?.len() > MAX_TEXT_BYTES {
+        return Ok(None);
+    }
+    let mut bytes = Vec::new();
+    file.take(MAX_TEXT_BYTES + 1).read_to_end(&mut bytes)?;
+    if bytes.len() as u64 > MAX_TEXT_BYTES || bytes.contains(&0) {
+        return Ok(None);
+    }
+    Ok(String::from_utf8(bytes).ok())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn persistence_updates_deletes_and_exact_priority() -> Result<()> {
+        let folder = tempfile::tempdir()?;
+        let root = folder.path().join("docs");
+        fs::create_dir(&root)?;
+        let db = folder.path().join("index.db");
+        fs::write(root.join("contract.txt"), "supplier cancellation agreement")?;
+        fs::write(root.join("other.txt"), "contract contract contract")?;
+        let mut index = SearchIndex::open(&db)?;
+        assert_eq!(index.index_folder(&root)?.indexed, 2);
+        assert_eq!(
+            index.search("contract.txt", 10)?[0].match_kind,
+            "exact_filename"
+        );
+        assert_eq!(index.search("cancellation", 10)?.len(), 1);
+        drop(index);
+        let mut index = SearchIndex::open(&db)?;
+        assert_eq!(index.stats()?.files, 2);
+        fs::write(root.join("contract.txt"), "replacement document")?;
+        fs::rename(root.join("other.txt"), root.join("renamed.txt"))?;
+        let report = index.index_folder(&root)?;
+        assert_eq!(report.removed, 1);
+        assert!(index.search("cancellation", 10)?.is_empty());
+        assert!(index.search("other.txt", 10)?.is_empty());
+        assert_eq!(index.search("renamed.txt", 10)?.len(), 1);
+        fs::remove_file(root.join("contract.txt"))?;
+        index.index_folder(&root)?;
+        assert_eq!(index.stats()?.files, 1);
+        Ok(())
+    }
+
+    #[test]
+    fn safe_queries_limits_and_unsupported_files() -> Result<()> {
+        let root = tempfile::tempdir()?;
+        fs::write(
+            root.path().join("notes.md"),
+            "German Kündigung and English cancellation",
+        )?;
+        fs::write(root.path().join("photo.jpg"), [0, 1, 2])?;
+        let mut index = SearchIndex::open(":memory:")?;
+        assert_eq!(index.index_folder(root.path())?.skipped, 1);
+        assert_eq!(index.search("Kündigung", 1)?.len(), 1);
+        assert!(index.search("\" OR *", 10)?.is_empty());
+        assert!(index.search("", 10)?.is_empty());
+        assert!(index.search("notes", 0)?.is_empty());
+        assert_eq!(index.search("photo.jpg", 10)?.len(), 1);
+        Ok(())
+    }
+
+    #[test]
+    fn invalid_root_preserves_index_and_unknown_schema_is_rejected() -> Result<()> {
+        let folder = tempfile::tempdir()?;
+        fs::write(folder.path().join("notes.txt"), "persistent evidence")?;
+        let mut index = SearchIndex::open(":memory:")?;
+        index.index_folder(folder.path())?;
+        assert!(index.index_folder(folder.path().join("missing")).is_err());
+        assert_eq!(index.search("evidence", 10)?.len(), 1);
+        let db = folder.path().join("future.db");
+        let connection = Connection::open(&db)?;
+        connection.execute_batch("PRAGMA user_version=999")?;
+        drop(connection);
+        assert!(SearchIndex::open(db).is_err());
+        Ok(())
+    }
+}

crates/searchi-core/tests/index_options.rs

@@ -0,0 +1,136 @@
+use anyhow::Result;
+use searchi_core::{IndexOptions, SearchIndex, SearchOptions};
+use std::fs;
+
+#[test]
+fn exclusions_database_and_unchanged_metadata() -> Result<()> {
+    let root = tempfile::tempdir()?;
+    for directory in [".git", "node_modules", "target", "private"] {
+        fs::create_dir(root.path().join(directory))?;
+        fs::write(root.path().join(directory).join("hidden.txt"), "secret")?;
+    }
+    fs::write(root.path().join("visible.txt"), "original content")?;
+    let mut index = SearchIndex::open(root.path().join("index.db"))?;
+    let options = IndexOptions {
+        excluded_directory_names: vec![
+            ".git".into(),
+            "node_modules".into(),
+            "target".into(),
+            "private".into(),
+        ],
+    };
+    assert_eq!(
+        index
+            .index_folder_with_options(root.path(), &options)?
+            .indexed,
+        1
+    );
+    assert_eq!(index.stats()?.files, 1);
+    let unchanged = index.index_folder_with_options(root.path(), &options)?;
+    assert_eq!(unchanged.unchanged, 1);
+    assert_eq!(unchanged.indexed, 0);
+    assert!(index.search("secret", 10)?.is_empty());
+    assert!(index.search("index.db", 10)?.is_empty());
+    fs::write(
+        root.path().join("visible.txt"),
+        "changed and longer content",
+    )?;
+    assert_eq!(
+        index
+            .index_folder_with_options(root.path(), &options)?
+            .indexed,
+        1
+    );
+    assert!(index.search("original", 10)?.is_empty());
+    assert_eq!(index.search("changed", 10)?.len(), 1);
+    // A new exclusion removes previously indexed entries from this root.
+    let mut options = IndexOptions::default();
+    index.index_folder_with_options(root.path(), &options)?;
+    assert_eq!(index.search("secret", 10)?.len(), 1);
+    options.excluded_directory_names.push("private".into());
+    assert_eq!(
+        index
+            .index_folder_with_options(root.path(), &options)?
+            .removed,
+        1
+    );
+    Ok(())
+}
+
+#[test]
+fn filters_apply_before_limit_and_respect_folder_boundaries() -> Result<()> {
+    let root = tempfile::tempdir()?;
+    let docs = root.path().join("docs");
+    let sibling = root.path().join("docs-more");
+    fs::create_dir(&docs)?;
+    fs::create_dir(&sibling)?;
+    fs::write(docs.join("shared.md"), "shared short")?;
+    fs::write(docs.join("shared.txt"), "shared considerably longer")?;
+    fs::write(sibling.join("shared.md"), "shared sibling")?;
+    let mut index = SearchIndex::open(":memory:")?;
+    index.index_folder(root.path())?;
+    let options = SearchOptions {
+        folder: Some(docs),
+        extension: Some(".MD".into()),
+        max_size: Some(15),
+        ..Default::default()
+    };
+    let results = index.search_with_options("shared", 1, &options)?;
+    assert_eq!(results.len(), 1);
+    assert_eq!(results[0].filename, "shared.md");
+    assert!(!results[0].path.contains("docs-more"));
+    let options = SearchOptions {
+        min_size: Some(20),
+        ..Default::default()
+    };
+    assert_eq!(index.search_with_options("shared", 10, &options)?.len(), 1);
+    let options = SearchOptions {
+        modified_before_unix_ms: Some(0),
+        ..Default::default()
+    };
+    assert!(index
+        .search_with_options("shared", 10, &options)?
+        .is_empty());
+    let options = SearchOptions {
+        min_size: Some(20),
+        max_size: Some(10),
+        ..Default::default()
+    };
+    assert!(index.search_with_options("shared", 10, &options).is_err());
+    Ok(())
+}
+
+#[test]
+fn migrates_v1_database_without_losing_search_records() -> Result<()> {
+    let root = tempfile::tempdir()?;
+    let db = root.path().join("legacy.db");
+    let connection = rusqlite::Connection::open(&db)?;
+    connection.execute_batch(
+        "CREATE TABLE files(id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE,
+        root TEXT NOT NULL, filename TEXT NOT NULL, content TEXT NOT NULL);
+        PRAGMA user_version=1;",
+    )?;
+    drop(connection);
+    let mut index = SearchIndex::open(&db)?;
+    fs::write(root.path().join("sample.txt"), "migration evidence")?;
+    index.index_folder(root.path())?;
+    assert_eq!(index.search("evidence", 10)?.len(), 1);
+    Ok(())
+}
+
+#[test]
+fn readers_open_and_search_during_uncommitted_writer() -> Result<()> {
+    let root = tempfile::tempdir()?;
+    let db = root.path().join("index.db");
+    fs::write(root.path().join("notes.txt"), "committed evidence")?;
+    let mut index = SearchIndex::open(&db)?;
+    index.index_folder(root.path())?;
+    let writer = rusqlite::Connection::open(&db)?;
+    writer.execute_batch("BEGIN IMMEDIATE; UPDATE files SET content='uncommitted replacement';")?;
+    // Opening a current schema must not issue DDL or acquire a write lock.
+    let reader = SearchIndex::open(&db)?;
+    assert_eq!(reader.search("evidence", 10)?.len(), 1);
+    assert!(reader.search("replacement", 10)?.is_empty());
+    writer.execute_batch("ROLLBACK;")?;
+    Ok(())
+}