Resolves issue #13

- Switched model to bge-small-en-v1.5
- Added lazy re-embedding
- Added model version tracking per vector
- Added conversion of vectors to the new model

internal/db/sqlite/migrations.go

@@ -283,6 +283,27 @@ var Migrations = []Migration{
 			ON user_prompts(claude_session_id, prompt_number);
 		`,
 	},
+	{
+		Version: 19,
+		Name:    "vectors_with_model_version",
+		SQL: `
+			-- Drop old vectors table (virtual tables cannot be altered)
+			DROP TABLE IF EXISTS vectors;
+
+			-- Recreate vectors table with model_version column
+			-- Uses bge-small-en-v1.5 embeddings (384 dimensions)
+			CREATE VIRTUAL TABLE IF NOT EXISTS vectors USING vec0(
+				doc_id TEXT PRIMARY KEY,
+				embedding float[384],
+				sqlite_id INTEGER,
+				doc_type TEXT,
+				field_type TEXT,
+				project TEXT,
+				scope TEXT,
+				model_version TEXT
+			);
+		`,
+	},
 }
 
 // MigrationManager handles database schema migrations.

internal/db/sqlite/observation.go

@@ -229,6 +229,25 @@ func (s *ObservationStore) GetAllRecentObservations(ctx context.Context, limit i
 	return scanObservationRows(rows)
 }
 
+// GetAllObservations retrieves all observations (for vector rebuild).
+func (s *ObservationStore) GetAllObservations(ctx context.Context) ([]*models.Observation, error) {
+	const query = `
+		SELECT id, sdk_session_id, project, COALESCE(scope, 'project') as scope, type, title, subtitle, facts, narrative,
+		       concepts, files_read, files_modified, file_mtimes, prompt_number, discovery_tokens,
+		       created_at, created_at_epoch
+		FROM observations
+		ORDER BY id
+	`
+
+	rows, err := s.store.QueryContext(ctx, query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	return scanObservationRows(rows)
+}
+
 // SearchObservationsFTS performs full-text search on observations.
 func (s *ObservationStore) SearchObservationsFTS(ctx context.Context, query, project string, limit int) ([]*models.Observation, error) {
 	if limit <= 0 {

internal/db/sqlite/prompt.go

@@ -199,6 +199,28 @@ func (s *PromptStore) GetAllRecentUserPrompts(ctx context.Context, limit int) ([
 	return scanPromptWithSessionRows(rows)
 }
 
+// GetAllPrompts retrieves all user prompts (for vector rebuild).
+func (s *PromptStore) GetAllPrompts(ctx context.Context) ([]*models.UserPromptWithSession, error) {
+	const query = `
+		SELECT up.id, up.claude_session_id, up.prompt_number, up.prompt_text,
+		       COALESCE(up.matched_observations, 0) as matched_observations,
+		       up.created_at, up.created_at_epoch,
+		       COALESCE(s.project, '') as project,
+		       COALESCE(s.sdk_session_id, '') as sdk_session_id
+		FROM user_prompts up
+		LEFT JOIN sdk_sessions s ON up.claude_session_id = s.claude_session_id
+		ORDER BY up.id
+	`
+
+	rows, err := s.store.QueryContext(ctx, query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	return scanPromptWithSessionRows(rows)
+}
+
 // FindRecentPromptByText finds a prompt with the same text for a session within the last few seconds.
 // This is used to detect duplicate hook invocations.
 // Returns (promptID, promptNumber, found).

internal/db/sqlite/summary.go

@@ -116,3 +116,21 @@ func (s *SummaryStore) GetAllRecentSummaries(ctx context.Context, limit int) ([]
 
 	return scanSummaryRows(rows)
 }
+
+// GetAllSummaries retrieves all summaries (for vector rebuild).
+func (s *SummaryStore) GetAllSummaries(ctx context.Context) ([]*models.SessionSummary, error) {
+	const query = `
+		SELECT id, sdk_session_id, project, request, investigated, learned, completed,
+		       next_steps, notes, prompt_number, discovery_tokens, created_at, created_at_epoch
+		FROM session_summaries
+		ORDER BY id
+	`
+
+	rows, err := s.store.QueryContext(ctx, query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	return scanSummaryRows(rows)
+}