diff --git a/src/cli.ts b/src/cli.ts
index 9b13603..1d75b04 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -61,7 +61,7 @@ function outputCollectionOptionError(command: Command, code: string, message: st
   }
   const exitCode = code === "path_not_found" ? 4
     : code === "missing_config" || code === "invalid_config" ? 3
-    : 1;
+      : 1;
   process.exit(exitCode);
 }
 
diff --git a/src/commands/base.ts b/src/commands/base.ts
index 7498348..62a48e9 100644
--- a/src/commands/base.ts
+++ b/src/commands/base.ts
@@ -8,6 +8,7 @@ import type { BaseFile } from "../base/parser.js";
 import { executeBase, BaseExecutionError } from "../base/executor.js";
 import { printResults } from "../base/formatter.js";
 import type { OutputFormat } from "../base/formatter.js";
+import { closeAndExit } from "../utils.js";
 
 export function registerBase(program: Command): void {
   const base = program
@@ -64,7 +65,7 @@ export function registerBase(program: Command): void {
         });
 
         printResults(results, opts.format as OutputFormat);
-        process.exit(0);
+        await closeAndExit(collection, 0);
       } catch (err) {
         if (err instanceof BaseExecutionError) {
           if (opts.format === "json") {
@@ -72,7 +73,7 @@ export function registerBase(program: Command): void {
           } else {
             console.error(chalk.red(`error: ${err.message}`));
           }
-          process.exit(err.code === "view_not_found" ? 1 : 1);
+          await closeAndExit(collection, err.code === "view_not_found" ? 1 : 1);
         }
         throw err;
       }
diff --git a/src/commands/create.ts b/src/commands/create.ts
index 9573049..ec62f8e 100644
--- a/src/commands/create.ts
+++ b/src/commands/create.ts
@@ -4,15 +4,15 @@ import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import type { MdbaseError } from "@callumalpass/mdbase";
 import yaml from "js-yaml";
-import { parseFieldValue } from "../utils.js";
+import { parseFieldValue, closeAndExit } from "../utils.js";
 
-function parseFields(fieldArgs: string[]): Record<string, unknown> {
+async function parseFields(fieldArgs: string[], collection: { close(): Promise<void> } | null): Promise<Record<string, unknown>> {
   const frontmatter: Record<string, unknown> = {};
   for (const f of fieldArgs) {
     const eqIdx = f.indexOf("=");
     if (eqIdx === -1) {
       console.error(chalk.red(`error: invalid field format: ${f} (expected key=value)`));
-      process.exit(1);
+      await closeAndExit(collection, 1);
     }
     const key = f.slice(0, eqIdx);
     const rawValue = f.slice(eqIdx + 1);
@@ -47,12 +47,12 @@ export function registerCreate(program: Command): void {
         } else {
           console.error(chalk.red(`error: ${openResult.error.message}`));
         }
-        process.exit(3);
+        await closeAndExit(null, 3);
       }
       const collection = openResult.collection!;
 
       // Parse field values
-      const frontmatter = opts.field ? parseFields(opts.field as string[]) : {};
+      const frontmatter = opts.field ? await parseFields(opts.field as string[], collection) : {};
 
       // Read body from stdin if requested
       let body: string | undefined = opts.body;
@@ -86,7 +86,7 @@ export function registerCreate(program: Command): void {
       }
 
       const result = await collection.create(input);
-      outputResult(result, relativePath, opts);
+      await outputResult(result, relativePath, opts, collection);
     });
 }
 
@@ -103,17 +103,18 @@ function formatIssue(issue: MdbaseError): string {
   return `  ${tag}${field}: ${issue.message} ${chalk.dim(`[${issue.code}]`)}`;
 }
 
-function outputResult(
+async function outputResult(
   result: { valid?: boolean; frontmatter?: Record<string, unknown>; body?: string; path?: string; error?: { code: string; message: string }; issues?: MdbaseError[] },
   requestedPath: string | undefined,
   opts: { format: string },
-): void {
+  collection: { close(): Promise<void> },
+): Promise<void> {
   if (result.error) {
     const exitCode = result.error.code === "path_conflict" ? 1
       : result.error.code === "unknown_type" ? 1
-      : result.error.code === "validation_failed" ? 2
-      : result.error.code === "permission_denied" ? 5
-      : 1;
+        : result.error.code === "validation_failed" ? 2
+          : result.error.code === "permission_denied" ? 5
+            : 1;
 
     if (opts.format === "json") {
       const output: Record<string, unknown> = { error: result.error };
@@ -129,7 +130,8 @@ function outputResult(
         }
       }
     }
-    process.exit(exitCode);
+    await closeAndExit(collection, exitCode);
+    return;
   }
 
   const outputPath = result.path ?? requestedPath;
@@ -175,5 +177,5 @@ function outputResult(
     }
   }
 
-  process.exit(0);
+  await closeAndExit(collection, 0);
 }
diff --git a/src/commands/delete.ts b/src/commands/delete.ts
index bb05241..4af507c 100644
--- a/src/commands/delete.ts
+++ b/src/commands/delete.ts
@@ -3,6 +3,7 @@ import path from "node:path";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import yaml from "js-yaml";
+import { closeAndExit } from "../utils.js";
 
 export function registerDelete(program: Command): void {
   program
@@ -35,14 +36,14 @@ export function registerDelete(program: Command): void {
       if (result.error) {
         const exitCode = result.error.code === "file_not_found" ? 4
           : result.error.code === "permission_denied" ? 5
-          : 1;
+            : 1;
 
         if (opts.format === "json") {
           console.log(JSON.stringify({ error: result.error }, null, 2));
         } else {
           console.error(chalk.red(`error: ${result.error.message}`));
         }
-        process.exit(exitCode);
+        await closeAndExit(collection, exitCode);
       }
 
       const brokenLinks = result.broken_links ?? [];
@@ -85,6 +86,6 @@ export function registerDelete(program: Command): void {
         }
       }
 
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
diff --git a/src/commands/diff.ts b/src/commands/diff.ts
index 17b6880..7bb7851 100644
--- a/src/commands/diff.ts
+++ b/src/commands/diff.ts
@@ -2,6 +2,7 @@ import { Command } from "commander";
 import path from "node:path";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
+import { closeAndExit } from "../utils.js";
 
 interface FieldDiff {
   field: string;
@@ -78,7 +79,7 @@ export function registerDiff(program: Command): void {
         } else {
           console.error(chalk.red(`error: ${pathA}: ${readA.error.message}`));
         }
-        process.exit(4);
+        await closeAndExit(collection, 4);
       }
       if (readB.error) {
         if (opts.format === "json") {
@@ -86,7 +87,7 @@ export function registerDiff(program: Command): void {
         } else {
           console.error(chalk.red(`error: ${pathB}: ${readB.error.message}`));
         }
-        process.exit(4);
+        await closeAndExit(collection, 4);
       }
 
       const fmA = readA.frontmatter ?? {};
@@ -136,7 +137,7 @@ export function registerDiff(program: Command): void {
       } else {
         if (result.identical) {
           console.log(chalk.green("Files are identical"));
-          process.exit(0);
+          await closeAndExit(collection, 0);
         }
 
         console.log(`${chalk.bold(pathA)} ${chalk.dim("vs")} ${chalk.bold(pathB)}`);
@@ -169,6 +170,6 @@ export function registerDiff(program: Command): void {
         }
       }
 
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
diff --git a/src/commands/export.ts b/src/commands/export.ts
index 7db6c58..929ff60 100644
--- a/src/commands/export.ts
+++ b/src/commands/export.ts
@@ -3,7 +3,7 @@ import fs from "node:fs";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import { stringify } from "csv-stringify/sync";
-import { splitList } from "../utils.js";
+import { splitList, closeAndExit } from "../utils.js";
 
 function formatValue(value: unknown): string {
   if (value === null || value === undefined) return "";
@@ -54,7 +54,7 @@ export function registerExport(program: Command): void {
         } else {
           console.error(chalk.red(`error: ${queryResult.error.message}`));
         }
-        process.exit(1);
+        await closeAndExit(collection, 1);
       }
 
       const results = queryResult.results as Array<{
@@ -120,6 +120,6 @@ export function registerExport(program: Command): void {
         console.log(output);
       }
 
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
diff --git a/src/commands/fmt.ts b/src/commands/fmt.ts
index 5d9b15c..5f72be4 100644
--- a/src/commands/fmt.ts
+++ b/src/commands/fmt.ts
@@ -6,6 +6,7 @@ import { Collection, loadConfig, loadTypes } from "@callumalpass/mdbase";
 import type { TypeDefinition } from "@callumalpass/mdbase";
 import yaml from "js-yaml";
 import matter from "gray-matter";
+import { closeAndExit } from "../utils.js";
 
 interface FmtFileResult {
   path: string;
@@ -59,7 +60,7 @@ export function registerFmt(program: Command): void {
           } else {
             console.error(chalk.red(`error: ${queryResult.error.message}`));
           }
-          process.exit(1);
+          await closeAndExit(collection, 1);
         }
         filePaths = (queryResult.results ?? []).map((r: { path: string }) => r.path);
       }
@@ -122,9 +123,9 @@ export function registerFmt(program: Command): void {
 
       // In --check mode, exit 1 if any files need formatting
       if (opts.check && changedCount > 0) {
-        process.exit(1);
+        await closeAndExit(collection, 1);
       }
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
 
diff --git a/src/commands/graph.ts b/src/commands/graph.ts
index 01ae028..02f52a7 100644
--- a/src/commands/graph.ts
+++ b/src/commands/graph.ts
@@ -1,6 +1,7 @@
 import { Command } from "commander";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
+import { closeAndExit } from "../utils.js";
 
 const WIKILINK_RE = /\[\[([^\]|]+)(?:\|[^\]]+)?\]\]/g;
 
@@ -178,7 +179,7 @@ export function registerGraph(program: Command): void {
           }
         }
       }
-      process.exit(0);
+      await closeAndExit(openResult.collection!, 0);
     });
 
   graph
@@ -216,7 +217,7 @@ export function registerGraph(program: Command): void {
           }
         }
       }
-      process.exit(0);
+      await closeAndExit(openResult.collection!, 0);
     });
 
   graph
@@ -246,7 +247,7 @@ export function registerGraph(program: Command): void {
         } else {
           console.error(chalk.red(`error: ${readResult.error.message}`));
         }
-        process.exit(4);
+        await closeAndExit(collection, 4);
       }
 
       const { incoming } = await buildGraph(collection);
@@ -264,7 +265,7 @@ export function registerGraph(program: Command): void {
           }
         }
       }
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 
   graph
@@ -317,6 +318,6 @@ export function registerGraph(program: Command): void {
         console.log(`  ${chalk.dim("Components:")}  ${result.connected_components}`);
         console.log(`  ${chalk.dim("Density:")}     ${result.density}`);
       }
-      process.exit(0);
+      await closeAndExit(openResult.collection!, 0);
     });
 }
diff --git a/src/commands/import.ts b/src/commands/import.ts
index b803d9d..76ac685 100644
--- a/src/commands/import.ts
+++ b/src/commands/import.ts
@@ -4,6 +4,7 @@ import path from "node:path";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import { parse } from "csv-parse/sync";
+import { closeAndExit } from "../utils.js";
 
 function coerceValue(value: string): unknown {
   if (value === "true") return true;
@@ -54,7 +55,7 @@ export function registerImport(program: Command): void {
         } else {
           console.error(chalk.red(`error: file not found: ${file}`));
         }
-        process.exit(4);
+        await closeAndExit(collection, 4);
       }
 
       const content = fs.readFileSync(csvPath, "utf-8");
@@ -102,7 +103,7 @@ export function registerImport(program: Command): void {
         }
       }
 
-      outputResult(result, opts.format);
+      outputResult(result, opts.format, collection);
     });
 
   imp
@@ -132,7 +133,7 @@ export function registerImport(program: Command): void {
         } else {
           console.error(chalk.red(`error: file not found: ${file}`));
         }
-        process.exit(4);
+        await closeAndExit(collection, 4);
       }
 
       const content = fs.readFileSync(jsonPath, "utf-8");
@@ -145,7 +146,7 @@ export function registerImport(program: Command): void {
         } else {
           console.error(chalk.red("error: failed to parse JSON file"));
         }
-        process.exit(1);
+        await closeAndExit(collection, 1);
         return;
       }
 
@@ -155,7 +156,7 @@ export function registerImport(program: Command): void {
         } else {
           console.error(chalk.red("error: JSON file must contain an array"));
         }
-        process.exit(1);
+        await closeAndExit(collection, 1);
         return;
       }
 
@@ -204,11 +205,11 @@ export function registerImport(program: Command): void {
         }
       }
 
-      outputResult(result, opts.format);
+      outputResult(result, opts.format, collection);
     });
 }
 
-function outputResult(result: ImportResult, format: string): void {
+async function outputResult(result: ImportResult, format: string, collection: { close(): Promise<void> }): Promise<void> {
   if (format === "json") {
     console.log(JSON.stringify(result, null, 2));
   } else {
@@ -228,5 +229,5 @@ function outputResult(result: ImportResult, format: string): void {
     }
   }
 
-  process.exit(result.failed > 0 ? 1 : 0);
+  await closeAndExit(collection, result.failed > 0 ? 1 : 0);
 }
diff --git a/src/commands/lint.ts b/src/commands/lint.ts
index 085ef91..edf5852 100644
--- a/src/commands/lint.ts
+++ b/src/commands/lint.ts
@@ -4,6 +4,7 @@ import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import type { MdbaseError } from "@callumalpass/mdbase";
 import yaml from "js-yaml";
+import { closeAndExit } from "../utils.js";
 
 interface LintIssue {
   path: string;
@@ -78,7 +79,7 @@ export function registerLint(program: Command): void {
           } else {
             console.error(chalk.red(`error: ${queryResult.error.message}`));
           }
-          process.exit(1);
+          await closeAndExit(collection, 1);
         }
         filePaths = (queryResult.results ?? []).map((r: { path: string }) => r.path);
       }
@@ -160,7 +161,7 @@ export function registerLint(program: Command): void {
       }
 
       const hasErrors = result.summary.errors > 0;
-      process.exit(hasErrors ? 2 : 0);
+      await closeAndExit(collection, hasErrors ? 2 : 0);
     });
 }
 
diff --git a/src/commands/query.ts b/src/commands/query.ts
index 6212c61..fba1c2c 100644
--- a/src/commands/query.ts
+++ b/src/commands/query.ts
@@ -2,7 +2,7 @@ import { Command } from "commander";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import Table from "cli-table3";
-import { splitList } from "../utils.js";
+import { splitList, closeAndExit } from "../utils.js";
 
 interface ResultRow {
   path: string;
@@ -95,7 +95,7 @@ export function registerQuery(program: Command): void {
           const eqIdx = f.indexOf("=");
           if (eqIdx === -1) {
             console.error(chalk.red(`error: invalid formula format: ${f} (expected name=expression)`));
-            process.exit(1);
+            await closeAndExit(collection, 1);
           }
           formulas[f.slice(0, eqIdx)] = f.slice(eqIdx + 1);
         }
@@ -118,7 +118,7 @@ export function registerQuery(program: Command): void {
         } else {
           console.error(chalk.red(`error: ${queryResult.error.message}`));
         }
-        process.exit(1);
+        await closeAndExit(collection, 1);
       }
 
       const results = queryResult.results as Array<{
@@ -132,7 +132,7 @@ export function registerQuery(program: Command): void {
       // --count: just print the count
       if (opts.count) {
         console.log(String(queryResult.meta?.total_count ?? results.length));
-        process.exit(0);
+        await closeAndExit(collection, 0);
       }
 
       if (results.length === 0) {
@@ -141,7 +141,7 @@ export function registerQuery(program: Command): void {
         } else if (opts.format !== "paths" && opts.format !== "csv" && opts.format !== "jsonl") {
           console.error(chalk.dim("No results"));
         }
-        process.exit(0);
+        await closeAndExit(collection, 0);
       }
 
       // Collect formula names
@@ -229,7 +229,7 @@ export function registerQuery(program: Command): void {
         }
       }
 
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
 
diff --git a/src/commands/read.ts b/src/commands/read.ts
index ab015ec..1d8a76f 100644
--- a/src/commands/read.ts
+++ b/src/commands/read.ts
@@ -3,6 +3,7 @@ import path from "node:path";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import yaml from "js-yaml";
+import { closeAndExit } from "../utils.js";
 
 type ReadResultExtras = {
   warnings?: Array<{ code: string; message: string; field?: string }>;
@@ -52,14 +53,14 @@ export function registerRead(program: Command): void {
       if (result.error) {
         const exitCode = result.error.code === "file_not_found" ? 4
           : result.error.code === "permission_denied" ? 5
-          : 1;
+            : 1;
 
         if (opts.format === "json") {
           console.log(JSON.stringify({ error: result.error }, null, 2));
         } else {
           console.error(chalk.red(`error: ${result.error.message}`));
         }
-        process.exit(exitCode);
+        await closeAndExit(collection, exitCode);
       }
 
       const frontmatter = opts.raw ? result.rawFrontmatter : result.frontmatter;
@@ -147,6 +148,6 @@ export function registerRead(program: Command): void {
         }
       }
 
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
diff --git a/src/commands/rename.ts b/src/commands/rename.ts
index 3da6524..a00c666 100644
--- a/src/commands/rename.ts
+++ b/src/commands/rename.ts
@@ -3,6 +3,7 @@ import path from "node:path";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import yaml from "js-yaml";
+import { closeAndExit } from "../utils.js";
 
 export function registerRename(program: Command): void {
   program
@@ -46,23 +47,23 @@ export function registerRename(program: Command): void {
         // but some ref updates failed. Show success output with warnings.
         if (result.error.code === "rename_ref_update_failed") {
           outputSuccess(relativeFrom, relativeTo, result, opts.format);
-          process.exit(0);
+          await closeAndExit(collection, 0);
         }
 
         const exitCode = result.error.code === "file_not_found" ? 4
           : result.error.code === "permission_denied" ? 5
-          : 1;
+            : 1;
 
         if (opts.format === "json") {
           console.log(JSON.stringify({ error: result.error }, null, 2));
         } else {
           console.error(chalk.red(`error: ${result.error.message}`));
         }
-        process.exit(exitCode);
+        await closeAndExit(collection, exitCode);
       }
 
       outputSuccess(relativeFrom, relativeTo, result, opts.format);
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
 
diff --git a/src/commands/schema.ts b/src/commands/schema.ts
index 4013064..b9151f2 100644
--- a/src/commands/schema.ts
+++ b/src/commands/schema.ts
@@ -4,6 +4,7 @@ import path from "node:path";
 import chalk from "chalk";
 import { Collection, loadConfig } from "@callumalpass/mdbase";
 import yaml from "js-yaml";
+import { closeAndExit } from "../utils.js";
 
 interface InferredField {
   type: string;
@@ -111,7 +112,7 @@ export function registerSchema(program: Command): void {
       });
       if (queryResult.error) {
         console.error(chalk.red(`error: ${queryResult.error.message}`));
-        process.exit(1);
+        await closeAndExit(collection, 1);
       }
 
       const files = queryResult.results as Array<{
@@ -129,7 +130,7 @@ export function registerSchema(program: Command): void {
         } else {
           console.log(chalk.dim("No untyped files found"));
         }
-        process.exit(0);
+        await closeAndExit(collection, 0);
       }
 
       // Group by field signature
@@ -159,7 +160,7 @@ export function registerSchema(program: Command): void {
         } else {
           console.log(chalk.dim(`No field groups with >= ${minFiles} files found`));
         }
-        process.exit(0);
+        await closeAndExit(collection, 0);
       }
 
       const inferredTypes: InferredType[] = [];
@@ -253,6 +254,6 @@ export function registerSchema(program: Command): void {
         }
       }
 
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
diff --git a/src/commands/stats.ts b/src/commands/stats.ts
index b6f4b80..d8e737e 100644
--- a/src/commands/stats.ts
+++ b/src/commands/stats.ts
@@ -1,6 +1,7 @@
 import { Command } from "commander";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
+import { closeAndExit } from "../utils.js";
 
 interface StatsResult {
   total_files: number;
@@ -43,7 +44,7 @@ export function registerStats(program: Command): void {
         } else {
           console.error(chalk.red(`error: ${queryResult.error.message}`));
         }
-        process.exit(1);
+        await closeAndExit(collection, 1);
       }
 
       const files = queryResult.results as Array<{
@@ -164,6 +165,6 @@ export function registerStats(program: Command): void {
         }
       }
 
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
diff --git a/src/commands/types.ts b/src/commands/types.ts
index f6c1fe6..91cd252 100644
--- a/src/commands/types.ts
+++ b/src/commands/types.ts
@@ -3,6 +3,7 @@ import chalk from "chalk";
 import yaml from "js-yaml";
 import { Collection, loadConfig, loadTypes, getType } from "@callumalpass/mdbase";
 import type { FieldDefinition, TypeDefinition } from "@callumalpass/mdbase";
+import { closeAndExit } from "../utils.js";
 
 function formatFieldType(field: FieldDefinition): string {
   let desc = field.type;
@@ -282,7 +283,7 @@ export function registerTypes(program: Command): void {
         } else {
           console.error(chalk.red(`error: ${openResult.error.message}`));
         }
-        process.exit(3);
+        await closeAndExit(null, 3);
       }
       const collection = openResult.collection!;
 
@@ -294,7 +295,8 @@ export function registerTypes(program: Command): void {
           const parsed = parseFieldSpec(f);
           if (!parsed) {
             console.error(chalk.red(`error: invalid field format: ${f} (expected name:type or name:type:required)`));
-            process.exit(1);
+            await closeAndExit(collection, 1);
+            return;
           }
           fields[parsed.name] = parsed.definition;
         }
@@ -334,15 +336,15 @@ export function registerTypes(program: Command): void {
       if (result.error) {
         const exitCode = result.error.code === "path_conflict" ? 1
           : result.error.code === "missing_parent_type" ? 1
-          : result.error.code === "invalid_type_definition" ? 2
-          : 1;
+            : result.error.code === "invalid_type_definition" ? 2
+              : 1;
 
         if (opts.format === "json") {
           console.log(JSON.stringify({ error: result.error }, null, 2));
         } else {
           console.error(chalk.red(`error: ${result.error.message}`));
         }
-        process.exit(exitCode);
+        await closeAndExit(collection, exitCode);
       }
 
       const typeDef = result.type!;
@@ -380,7 +382,7 @@ export function registerTypes(program: Command): void {
         }
       }
 
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
 
diff --git a/src/commands/update.ts b/src/commands/update.ts
index bfe6c63..cb8950a 100644
--- a/src/commands/update.ts
+++ b/src/commands/update.ts
@@ -3,15 +3,15 @@ import path from "node:path";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import yaml from "js-yaml";
-import { parseFieldValue } from "../utils.js";
+import { parseFieldValue, closeAndExit } from "../utils.js";
 
-function parseFields(fieldArgs: string[]): Record<string, unknown> {
+async function parseFields(fieldArgs: string[], collection: { close(): Promise<void> } | null): Promise<Record<string, unknown>> {
   const fields: Record<string, unknown> = {};
   for (const f of fieldArgs) {
     const eqIdx = f.indexOf("=");
     if (eqIdx === -1) {
       console.error(chalk.red(`error: invalid field format: ${f} (expected key=value)`));
-      process.exit(1);
+      await closeAndExit(collection, 1);
     }
     const key = f.slice(0, eqIdx);
     const rawValue = f.slice(eqIdx + 1);
@@ -52,11 +52,11 @@ export function registerUpdate(program: Command): void {
       // Need at least one thing to update
       if (!opts.field && opts.body === undefined && !opts.bodyStdin) {
         console.error(chalk.red("error: nothing to update (provide --field or --body)"));
-        process.exit(1);
+        await closeAndExit(collection, 1);
       }
 
       // Parse field values
-      const fields = opts.field ? parseFields(opts.field as string[]) : undefined;
+      const fields = opts.field ? await parseFields(opts.field as string[], collection) : undefined;
 
       // Read body from stdin if requested
       let body: string | undefined = opts.body;
@@ -89,15 +89,15 @@ export function registerUpdate(program: Command): void {
       if (result.error) {
         const exitCode = result.error.code === "file_not_found" ? 4
           : result.error.code === "validation_failed" ? 2
-          : result.error.code === "permission_denied" ? 5
-          : 1;
+            : result.error.code === "permission_denied" ? 5
+              : 1;
 
         if (opts.format === "json") {
           console.log(JSON.stringify({ error: result.error }, null, 2));
         } else {
           console.error(chalk.red(`error: ${result.error.message}`));
         }
-        process.exit(exitCode);
+        await closeAndExit(collection, exitCode);
       }
 
       switch (opts.format) {
@@ -141,6 +141,6 @@ export function registerUpdate(program: Command): void {
         }
       }
 
-      process.exit(0);
+      await closeAndExit(collection, 0);
     });
 }
diff --git a/src/commands/validate.ts b/src/commands/validate.ts
index bab06f1..7b6232d 100644
--- a/src/commands/validate.ts
+++ b/src/commands/validate.ts
@@ -3,6 +3,7 @@ import path from "node:path";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import type { MdbaseError } from "@callumalpass/mdbase";
+import { closeAndExit } from "../utils.js";
 
 function formatIssue(issue: MdbaseError): string {
   const severity = issue.severity ?? "error";
@@ -87,7 +88,7 @@ export function registerValidate(program: Command): void {
           }
         }
 
-        process.exit(result.valid ? 0 : 2);
+        await closeAndExit(collection, result.valid ? 0 : 2);
       } else {
         // Validate specific files
         let allValid = true;
@@ -152,7 +153,7 @@ export function registerValidate(program: Command): void {
           }
         }
 
-        process.exit(allValid ? 0 : 2);
+        await closeAndExit(collection, allValid ? 0 : 2);
       }
     });
 }
diff --git a/src/commands/watch.ts b/src/commands/watch.ts
index 5b6fcb7..da492c1 100644
--- a/src/commands/watch.ts
+++ b/src/commands/watch.ts
@@ -2,6 +2,7 @@ import { Command } from "commander";
 import chalk from "chalk";
 import { Collection } from "@callumalpass/mdbase";
 import { watch as chokidarWatch } from "chokidar";
+import { closeAndExit } from "../utils.js";
 
 function timestamp(): string {
   return new Date().toISOString().replace("T", " ").replace(/\.\d+Z$/, "");
@@ -112,7 +113,7 @@ export function registerWatch(program: Command): void {
           } else {
             console.log(`\n${chalk.dim(timestamp())} ${chalk.dim("stopped")}`);
           }
-          process.exit(0);
+          closeAndExit(collection, 0);
         });
       };
 
diff --git a/src/utils.ts b/src/utils.ts
index 9ae8d6a..4b7ad63 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,3 +1,42 @@
+/**
+ * Gracefully close a Collection and exit the process.
+ *
+ * On Windows, calling process.exit() while a Collection still holds open
+ * handles (sql.js WASM database, prepared statements) triggers a libuv
+ * assertion failure:
+ *
+ *   Assertion failed: !(handle->flags & UV_HANDLE_CLOSING),
+ *   file src\win\async.c, line 76
+ *
+ * Always close the collection before exiting to release all internal
+ * resources (flush the SQLite cache, free prepared statements, close the
+ * database) so the event loop can shut down cleanly.
+ *
+ * After closing, we schedule process.exit() on a short timer so that
+ * any pending libuv close-callbacks (e.g. the uv_async_t torn down by
+ * the WASM runtime) can fire before the process terminates.  The function
+ * itself never resolves, so callers see it as Promise<never> and do not
+ * execute any code after it.
+ */
+export async function closeAndExit(
+  collection: { close(): Promise<void> } | null | undefined,
+  code: number,
+): Promise<never> {
+  if (collection) {
+    try {
+      await collection.close();
+    } catch {
+      // Ignore cleanup errors — we're exiting anyway.
+    }
+  }
+  process.exitCode = code;
+  // Schedule process.exit() after a short delay so libuv close-callbacks
+  // can finish before the handle list is torn down.
+  setTimeout(() => process.exit(code), 50);
+  // Never resolve — the timer above will terminate the process.
+  return new Promise<never>(() => { });
+}
+
 export function splitList(value: string | undefined): string[] | undefined {
   if (value === undefined) return undefined;
   const parts = value.split(",").map((s) => s.trim()).filter((s) => s.length > 0);
diff --git a/test/fixtures/invalid-collection/.mdbase/cache.sqlite b/test/fixtures/invalid-collection/.mdbase/cache.sqlite
index 6147c8e..70dcd86 100644
Binary files a/test/fixtures/invalid-collection/.mdbase/cache.sqlite and b/test/fixtures/invalid-collection/.mdbase/cache.sqlite differ
diff --git a/test/fixtures/valid-collection/.mdbase/cache.sqlite b/test/fixtures/valid-collection/.mdbase/cache.sqlite
index 8d8b067..bcc6834 100644
Binary files a/test/fixtures/valid-collection/.mdbase/cache.sqlite and b/test/fixtures/valid-collection/.mdbase/cache.sqlite differ