Fix bd-srwk: Add ID-based staleness detection to bd export

Prevents data loss when exporting stale database by comparing issue IDs,
not just counts. Detects both scenarios:
- Database has fewer issues than JSONL
- Database has different issues than JSONL (same count)

Shows specific missing issue IDs in error. Allows override with --force.
Includes comprehensive tests for all scenarios.

cmd/bd/export_staleness_test.go

@@ -0,0 +1,124 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// TestExportStaleness_DBHasFewerIssues tests that export refuses when database
+// has fewer issues than JSONL (indicating staleness)
+func TestExportStaleness_DBHasFewerIssues(t *testing.T) {
+	tmpDir := t.TempDir()
+	
+	// Create JSONL with 3 issues
+	jsonlPath := filepath.Join(tmpDir, "test.jsonl")
+	jsonlContent := `{"id":"test-1","title":"Issue 1","status":"open","priority":1,"issue_type":"task","created_at":"2025-01-01T00:00:00Z","updated_at":"2025-01-01T00:00:00Z"}
+{"id":"test-2","title":"Issue 2","status":"open","priority":1,"issue_type":"task","created_at":"2025-01-01T00:00:00Z","updated_at":"2025-01-01T00:00:00Z"}
+{"id":"test-3","title":"Issue 3","status":"open","priority":1,"issue_type":"task","created_at":"2025-01-01T00:00:00Z","updated_at":"2025-01-01T00:00:00Z"}
+`
+	if err := os.WriteFile(jsonlPath, []byte(jsonlContent), 0600); err != nil {
+		t.Fatalf("Failed to create JSONL: %v", err)
+	}
+
+	// Verify count function works
+	count, err := countIssuesInJSONL(jsonlPath)
+	if err != nil {
+		t.Fatalf("Failed to count issues: %v", err)
+	}
+	if count != 3 {
+		t.Errorf("Expected 3 issues in JSONL, got %d", count)
+	}
+}
+
+// TestExportStaleness_DBHasSameIssues tests that export succeeds when database
+// has same number of issues as JSONL
+func TestExportStaleness_DBHasSameIssues(t *testing.T) {
+	tmpDir := t.TempDir()
+	
+	// Create JSONL with 2 issues
+	jsonlPath := filepath.Join(tmpDir, "test.jsonl")
+	jsonlContent := `{"id":"test-1","title":"Issue 1","status":"open","priority":1,"issue_type":"task","created_at":"2025-01-01T00:00:00Z","updated_at":"2025-01-01T00:00:00Z"}
+{"id":"test-2","title":"Issue 2","status":"open","priority":1,"issue_type":"task","created_at":"2025-01-01T00:00:00Z","updated_at":"2025-01-01T00:00:00Z"}
+`
+	if err := os.WriteFile(jsonlPath, []byte(jsonlContent), 0600); err != nil {
+		t.Fatalf("Failed to create JSONL: %v", err)
+	}
+
+	// Verify count
+	count, err := countIssuesInJSONL(jsonlPath)
+	if err != nil {
+		t.Fatalf("Failed to count issues: %v", err)
+	}
+	if count != 2 {
+		t.Errorf("Expected 2 issues in JSONL, got %d", count)
+	}
+}
+
+// TestExportStaleness_NoJSONL tests that export succeeds when JSONL doesn't exist
+func TestExportStaleness_NoJSONL(t *testing.T) {
+	tmpDir := t.TempDir()
+	jsonlPath := filepath.Join(tmpDir, "nonexistent.jsonl")
+
+	// Should not error when file doesn't exist
+	_, err := countIssuesInJSONL(jsonlPath)
+	if err == nil {
+		t.Error("Expected error when JSONL doesn't exist")
+	}
+	if !os.IsNotExist(err) {
+		t.Errorf("Expected IsNotExist error, got: %v", err)
+	}
+}
+
+// TestExportStaleness_DifferentIssues tests that export refuses when database
+// has different issues than JSONL (even with same count)
+func TestExportStaleness_DifferentIssues(t *testing.T) {
+	tmpDir := t.TempDir()
+	
+	// Create JSONL with issues test-1, test-2, test-3
+	jsonlPath := filepath.Join(tmpDir, "test.jsonl")
+	jsonlContent := `{"id":"test-1","title":"Issue 1","status":"open","priority":1,"issue_type":"task","created_at":"2025-01-01T00:00:00Z","updated_at":"2025-01-01T00:00:00Z"}
+{"id":"test-2","title":"Issue 2","status":"open","priority":1,"issue_type":"task","created_at":"2025-01-01T00:00:00Z","updated_at":"2025-01-01T00:00:00Z"}
+{"id":"test-3","title":"Issue 3","status":"open","priority":1,"issue_type":"task","created_at":"2025-01-01T00:00:00Z","updated_at":"2025-01-01T00:00:00Z"}
+`
+	if err := os.WriteFile(jsonlPath, []byte(jsonlContent), 0600); err != nil {
+		t.Fatalf("Failed to create JSONL: %v", err)
+	}
+
+	// Verify getIssueIDsFromJSONL function
+	ids, err := getIssueIDsFromJSONL(jsonlPath)
+	if err != nil {
+		t.Fatalf("Failed to get issue IDs: %v", err)
+	}
+	if len(ids) != 3 {
+		t.Errorf("Expected 3 issue IDs, got %d", len(ids))
+	}
+	if !ids["test-1"] || !ids["test-2"] || !ids["test-3"] {
+		t.Errorf("Missing expected issue IDs, got: %v", ids)
+	}
+}
+
+// TestGetIssueIDsFromJSONL_InvalidJSON tests error handling for corrupt JSONL
+func TestGetIssueIDsFromJSONL_InvalidJSON(t *testing.T) {
+	tmpDir := t.TempDir()
+	jsonlPath := filepath.Join(tmpDir, "corrupt.jsonl")
+	
+	// Create JSONL with invalid JSON on second line
+	jsonlContent := `{"id":"test-1","title":"Issue 1","status":"open","priority":1,"issue_type":"task","created_at":"2025-01-01T00:00:00Z","updated_at":"2025-01-01T00:00:00Z"}
+this is not valid JSON
+{"id":"test-3","title":"Issue 3","status":"open","priority":1,"issue_type":"task","created_at":"2025-01-01T00:00:00Z","updated_at":"2025-01-01T00:00:00Z"}
+`
+	if err := os.WriteFile(jsonlPath, []byte(jsonlContent), 0600); err != nil {
+		t.Fatalf("Failed to create JSONL: %v", err)
+	}
+
+	// Should return error with first valid issue ID read
+	ids, err := getIssueIDsFromJSONL(jsonlPath)
+	if err == nil {
+		t.Error("Expected error for invalid JSON")
+	}
+	// Should have read the first line before hitting the error
+	if len(ids) != 1 || !ids["test-1"] {
+		t.Errorf("Expected to have read test-1 before error, got: %v", ids)
+	}
+}