Update 6 SQLite

CHANGELOG-SQLITE-STARTUP-FIX.md

@@ -0,0 +1,39 @@
+# SQLite startup fix
+
+## Problem
+
+Some installations aborted during `graph.Open` with an opaque modernc SQLite error similar to:
+
+```text
+SQL logic error: out of memory (1)
+```
+
+The original startup path applied a 64 MiB SQLite page cache, a 256 MiB mmap window and `temp_store=MEMORY` while the connection was being opened. Those settings are unnecessary because the live graph and embeddings already reside in Go memory. The DSN-based PRAGMA list also made it impossible to identify which startup step failed.
+
+## Changes
+
+- Open SQLite using a plain absolute filename.
+- Verify that `BRAIN_DATA_DIR` exists, is a directory and is writable before opening SQLite.
+- Reject a `graph.db` path that is accidentally a directory.
+- Apply PRAGMAs individually with step-specific error messages.
+- Use conservative storage defaults:
+  - `cache_size=-8192` (approximately 8 MiB)
+  - `mmap_size=0`
+  - `temp_store=FILE`
+  - WAL, `synchronous=NORMAL`, foreign keys and a 5-second busy timeout remain enabled.
+- Persist and report the journal mode actually selected by SQLite.
+- Add the dependency checksums to `go.sum` and copy both `go.mod` and `go.sum` in the Docker dependency layer.
+
+## Recovery
+
+Because this is a staging-only database, remove files left by a failed first start before rebuilding:
+
+```bash
+docker compose stop brain
+docker compose run --rm --no-deps --entrypoint sh brain -c '
+  rm -f /app/data/graph.db /app/data/graph.db-wal /app/data/graph.db-shm
+'
+docker compose up -d --build --force-recreate brain
+```
+
+If startup still fails, the new error includes the exact phase, for example an unwritable data directory or a failed WAL configuration.