2026-05-09: Unify dev database — strata-dev.db across all dev modes

Problem

Three dev modes used three different database files:

Mode	Database (before)
npm run docker:dev	backend/.data/strata-dev.db ✅
npm run tauri:dev	~/Library/Application Support/Strata-Dev/strata.db ❌
cd backend && npm run start:dev	backend/.data/strata.db ❌

Naming convention violated: strata.db is the production database name. All dev modes must use strata-dev.db.

Sharing violated: Tauri dev stored its database in the macOS app data directory, completely separate from Docker dev data — so changes made in Docker were invisible in Tauri and vice versa.

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Decision

All dev modes share backend/.data/strata-dev.db. Production (Tauri release build) keeps ~/Library/Application Support/Strata/strata.db.

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Files Changed

File	Change
backend/.env	strata.db → strata-dev.db
backend/.env.example	Same
src-tauri/src/lib.rs	data_dir() dev branch → repo-relative backend/.data/; ensure_data_dir() dev → strata-dev.db

src-tauri/src/lib.rs — key change

fn data_dir() -> std::path::PathBuf {
    if is_dev_build() {
        // Repo-relative path shared with docker:dev and start:dev
        let manifest = std::path::Path::new(env!("CARGO_MANIFEST_DIR"));
        let repo_root = manifest.parent().expect("CARGO_MANIFEST_DIR has no parent");
        repo_root.join("backend").join(".data")
    } else {
        let mut dir = dirs::data_dir().expect("could not determine app data directory");
        dir.push("Strata");
        dir
    }
}

fn ensure_data_dir() -> String {
    let dir = data_dir();
    std::fs::create_dir_all(&dir).expect("could not create data directory");
    let db_file = if is_dev_build() { "strata-dev.db" } else { "strata.db" };
    format!("file:{}", dir.join(db_file).display())
}

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Execution Summary

Commit: see git log

Actual changes

• backend/.env and .env.example: one-line change, strata.db → strata-dev.db
• src-tauri/src/lib.rs: data_dir() and ensure_data_dir() rewritten to use CARGO_MANIFEST_DIR for repo-relative dev path

Deviations from plan

None — implemented exactly as designed.

Test results

Gate	Result
Backend unit	✅ 265 tests passed
Backend e2e	✅ 69 tests passed
Frontend unit	⏭ skipped (not affected)
Frontend e2e	⏭ skipped (not affected)

Key discoveries

• CARGO_MANIFEST_DIR (src-tauri/) is available at compile time in lib.rs, making a simple manifest.parent() sufficient to reach repo root — no runtime path gymnastics needed.
• The old Strata-Dev/ macOS app data directory is now unused by dev builds. Existing data there can be migrated manually by copying ~/Library/Application Support/Strata-Dev/strata.db to backend/.data/strata-dev.db if needed.