diff --git a/src/infrastructure/persistence/catalog_store.ts b/src/infrastructure/persistence/catalog_store.ts
index 0a6e2661..b08cb82e 100644
--- a/src/infrastructure/persistence/catalog_store.ts
+++ b/src/infrastructure/persistence/catalog_store.ts
@@ -20,6 +20,9 @@
 import { DatabaseSync } from "node:sqlite";
 import { dirname } from "@std/path";
 import { ensureDirSync } from "@std/fs";
+import { getLogger } from "@logtape/logtape";
+
+const logger = getLogger(["swamp", "persistence", "catalog"]);
 
 /**
  * A single row in the catalog table, representing one version of a data
@@ -559,9 +562,19 @@ export class CatalogStore {
    * Must be called outside any open transaction. Acquires an exclusive lock
    * and rewrites the entire database file — on a large catalog this may take
    * several seconds. Safe to call only when no other connections are active.
+   *
+   * Returns `true` if VACUUM succeeded, `false` if it was skipped due to a
+   * runtime limitation (e.g. SQLITE_LIMIT_ATTACHED=0 in the canary Deno
+   * runtime).
    */
-  vacuum(): void {
-    this.db.exec("VACUUM");
+  vacuum(): boolean {
+    try {
+      this.db.exec("VACUUM");
+      return true;
+    } catch (error) {
+      logger.warn`VACUUM skipped: ${error}`;
+      return false;
+    }
   }
 
   /**
diff --git a/src/infrastructure/persistence/catalog_store_test.ts b/src/infrastructure/persistence/catalog_store_test.ts
index 2bfc588a..3f040fe7 100644
--- a/src/infrastructure/persistence/catalog_store_test.ts
+++ b/src/infrastructure/persistence/catalog_store_test.ts
@@ -582,6 +582,17 @@ Deno.test("CatalogStore: checkpoint returns WAL page counts and truncates WAL",
   store.close();
 });
 
+Deno.test("CatalogStore: vacuum returns boolean and does not throw", () => {
+  const dbPath = makeTempDbPath();
+  const store = new CatalogStore(dbPath);
+  store.upsert(makeRow());
+
+  const result = store.vacuum();
+  assertEquals(typeof result, "boolean");
+
+  store.close();
+});
+
 Deno.test("CatalogStore: invalidate clears populated flag but keeps data", () => {
   const dbPath = makeTempDbPath();
   const store = new CatalogStore(dbPath);
diff --git a/src/libswamp/datastores/compact.ts b/src/libswamp/datastores/compact.ts
index bf5b5d6c..3fa13d06 100644
--- a/src/libswamp/datastores/compact.ts
+++ b/src/libswamp/datastores/compact.ts
@@ -27,6 +27,8 @@ export interface DatastoreCompactData {
   walPagesCheckpointed: number;
   /** Bytes reclaimed from the main database file after VACUUM. */
   dbBytesReclaimed: number;
+  /** True when VACUUM was skipped due to a runtime limitation. */
+  vacuumSkipped: boolean;
 }
 
 export type DatastoreCompactEvent =
@@ -38,7 +40,7 @@ export type DatastoreCompactEvent =
 /** Dependencies for the datastore compact operation. */
 export interface DatastoreCompactDeps {
   checkpoint: () => { walPagesTotal: number; walPagesCheckpointed: number };
-  vacuum: () => void;
+  vacuum: () => boolean;
   catalogDbSize: () => Promise<number>;
 }
 
@@ -58,7 +60,7 @@ export async function* datastoreCompact(
       const beforeSize = await deps.catalogDbSize();
 
       yield { kind: "vacuuming" } as const;
-      deps.vacuum();
+      const vacuumed = deps.vacuum();
       const afterSize = await deps.catalogDbSize();
 
       yield {
@@ -67,6 +69,7 @@ export async function* datastoreCompact(
           walPagesTotal: stats.walPagesTotal,
           walPagesCheckpointed: stats.walPagesCheckpointed,
           dbBytesReclaimed: Math.max(0, beforeSize - afterSize),
+          vacuumSkipped: !vacuumed,
         },
       };
     })(),
diff --git a/src/libswamp/datastores/compact_test.ts b/src/libswamp/datastores/compact_test.ts
index bedb8d61..e4771834 100644
--- a/src/libswamp/datastores/compact_test.ts
+++ b/src/libswamp/datastores/compact_test.ts
@@ -41,7 +41,7 @@ function makeDeps(
 ): DatastoreCompactDeps {
   return {
     checkpoint: () => ({ walPagesTotal: 10, walPagesCheckpointed: 10 }),
-    vacuum: () => {},
+    vacuum: () => true,
     catalogDbSize: () => Promise.resolve(0),
     ...overrides,
   };
@@ -102,5 +102,22 @@ Deno.test("datastoreCompact: dbBytesReclaimed is 0 when db size does not decreas
   const completed = events.find((e) => e.kind === "completed");
   if (completed?.kind === "completed") {
     assertEquals(completed.data.dbBytesReclaimed, 0);
+    assertEquals(completed.data.vacuumSkipped, false);
+  }
+});
+
+Deno.test("datastoreCompact: reports vacuumSkipped when vacuum returns false", async () => {
+  await initializeLogging({});
+  const ctx = createLibSwampContext({});
+  const deps = makeDeps({
+    vacuum: () => false,
+  });
+
+  const events = await collectEvents(datastoreCompact(ctx, deps));
+  const completed = events.find((e) => e.kind === "completed");
+  assertEquals(completed?.kind, "completed");
+  if (completed?.kind === "completed") {
+    assertEquals(completed.data.vacuumSkipped, true);
+    assertEquals(completed.data.dbBytesReclaimed, 0);
   }
 });
diff --git a/src/presentation/renderers/datastore_compact.ts b/src/presentation/renderers/datastore_compact.ts
index 3690f9ef..f12420c7 100644
--- a/src/presentation/renderers/datastore_compact.ts
+++ b/src/presentation/renderers/datastore_compact.ts
@@ -47,7 +47,10 @@ class LogDatastoreCompactRenderer implements Renderer<DatastoreCompactEvent> {
         } else {
           logger.info`WAL checkpointed and truncated`;
         }
-        if (e.data.dbBytesReclaimed > 0) {
+        if (e.data.vacuumSkipped) {
+          logger
+            .warn`VACUUM skipped (runtime limitation) — WAL checkpoint still reclaimed space`;
+        } else if (e.data.dbBytesReclaimed > 0) {
           logger
             .info`Catalog compacted: reclaimed ${e.data.dbBytesReclaimed} bytes`;
         } else {
@@ -72,6 +75,7 @@ class JsonDatastoreCompactRenderer implements Renderer<DatastoreCompactEvent> {
             walPagesTotal: e.data.walPagesTotal,
             walPagesCheckpointed: e.data.walPagesCheckpointed,
             dbBytesReclaimed: e.data.dbBytesReclaimed,
+            vacuumSkipped: e.data.vacuumSkipped,
           },
           null,
           2,