diff --git a/ext/wasm/index.html b/ext/wasm/index.html
index a1cc194854..562bb9b5ef 100644
--- a/ext/wasm/index.html
+++ b/ext/wasm/index.html
@@ -50,7 +50,7 @@
           worker due to an Emscripten limitation.</li>
         <li><a href='scratchpad-opfs-worker.html'>scratchpad-opfs-worker</a>:
           experimenting with OPFS from a Worker thread (without WASMFS).</li>
-        <li><a href='x-sync-async.html'>x-sync-async</a> is an
+        <li><a href='x-sync-async.html?opfs-sanity-check&opfs-verbose'>x-sync-async</a> is an
           experiment in implementing a syncronous sqlite3 VFS proxy
           for a fully synchronous backend interface (namely OPFS), using SharedArrayBuffer
           and the Atomics APIs to regulate communication between the synchronous
diff --git a/ext/wasm/x-sync-async.html b/ext/wasm/x-sync-async.html
index ec0a6353b5..b83d93378c 100644
--- a/ext/wasm/x-sync-async.html
+++ b/ext/wasm/x-sync-async.html
@@ -17,6 +17,6 @@
     </div>
     <div id='test-output'>
     </div>
-    <script>new Worker("x-sync-async.js");</script>
+    <script>new Worker("x-sync-async.js"+self.location.search);</script>
   </body>
 </html>
diff --git a/ext/wasm/x-sync-async.js b/ext/wasm/x-sync-async.js
index d36dc1700f..203c8eece4 100644
--- a/ext/wasm/x-sync-async.js
+++ b/ext/wasm/x-sync-async.js
@@ -44,7 +44,6 @@ const initOpfsVfs = function(sqlite3){
   const error =  (...args)=>{
     console.error(logPrefix,...args);
   };
-  warn("This file is very much experimental and under construction.",self.location.pathname);
 
   if(self.window===self ||
      !self.SharedArrayBuffer ||
@@ -56,7 +55,7 @@ const initOpfsVfs = function(sqlite3){
     warn("This environment does not have OPFS support.");
     return;
   }
-
+  warn("This file is very much experimental and under construction.",self.location.pathname);
   const capi = sqlite3.capi;
   const wasm = capi.wasm;
   const sqlite3_vfs = capi.sqlite3_vfs
@@ -65,6 +64,8 @@ const initOpfsVfs = function(sqlite3){
         || toss("Missing sqlite3.capi.sqlite3_file object.");
   const sqlite3_io_methods = capi.sqlite3_io_methods
         || toss("Missing sqlite3.capi.sqlite3_io_methods object.");
+  const StructBinder = sqlite3.StructBinder || toss("Missing sqlite3.StructBinder.");
+  const thisUrl = new URL(self.location.href);
 
   const W = new Worker("sqlite3-opfs-async-proxy.js");
   const wMsg = (type,payload)=>W.postMessage({type,payload});
@@ -76,7 +77,7 @@ const initOpfsVfs = function(sqlite3){
      of data may be added to it.
   */
   const state = Object.create(null);
-  state.verbose = 2;
+  state.verbose = thisUrl.searchParams.has('opfs-verbose') ? 3 : 2;
   state.fileBufferSize = 1024 * 64 + 8 /* size of fileHandle.sab. 64k = max sqlite3 page size */;
   state.fbInt64Offset = state.fileBufferSize - 8 /*spot in fileHandle.sab to store an int64*/;
   state.opIds = Object.create(null);
@@ -110,7 +111,6 @@ const initOpfsVfs = function(sqlite3){
   });
 
   const isWorkerErrCode = (n)=>!!state.sq3Codes._reverse[n];
-  
   const opStore = (op,val=-1)=>Atomics.store(state.opSABView, state.opIds[op], val);
   const opWait = (op,val=-1)=>Atomics.wait(state.opSABView, state.opIds[op], val);
 
@@ -128,12 +128,6 @@ const initOpfsVfs = function(sqlite3){
     return Atomics.load(state.opSABView, state.opIds[op]);
   };
 
-  const wait = (ms,value)=>{
-    return new Promise((resolve)=>{
-      setTimeout(()=>resolve(value), ms);
-    });
-  };
-
   /**
      Generates a random ASCII string len characters long, intended for
      use as a temporary file name.
@@ -194,6 +188,75 @@ const initOpfsVfs = function(sqlite3){
      environment or the other when sqlite3_os_end() is called (_if_ it
      gets called at all in a wasm build, which is undefined).
   */
+
+  /**
+     Installs a StructBinder-bound function pointer member of the
+     given name and function in the given StructType target object.
+     It creates a WASM proxy for the given function and arranges for
+     that proxy to be cleaned up when tgt.dispose() is called.  Throws
+     on the slightest hint of error (e.g. tgt is-not-a StructType,
+     name does not map to a struct-bound member, etc.).
+
+     Returns a proxy for this function which is bound to tgt and takes
+     2 args (name,func). That function returns the same thing,
+     permitting calls to be chained.
+
+     If called with only 1 arg, it has no side effects but returns a
+     func with the same signature as described above.
+  */
+  const installMethod = function callee(tgt, name, func){
+    if(!(tgt instanceof StructBinder.StructType)){
+      toss("Usage error: target object is-not-a StructType.");
+    }
+    if(1===arguments.length){
+      return (n,f)=>callee(tgt,n,f);
+    }
+    if(!callee.argcProxy){
+      callee.argcProxy = function(func,sig){
+        return function(...args){
+          if(func.length!==arguments.length){
+            toss("Argument mismatch. Native signature is:",sig);
+          }
+          return func.apply(this, args);
+        }
+      };
+      callee.removeFuncList = function(){
+        if(this.ondispose.__removeFuncList){
+          this.ondispose.__removeFuncList.forEach(
+            (v,ndx)=>{
+              if('number'===typeof v){
+                try{wasm.uninstallFunction(v)}
+                catch(e){/*ignore*/}
+              }
+              /* else it's a descriptive label for the next number in
+                 the list. */
+            }
+          );
+          delete this.ondispose.__removeFuncList;
+        }
+      };
+    }/*static init*/
+    const sigN = tgt.memberSignature(name);
+    if(sigN.length<2){
+      toss("Member",name," is not a function pointer. Signature =",sigN);
+    }
+    const memKey = tgt.memberKey(name);
+    //log("installMethod",tgt, name, sigN);
+    const fProxy = 1
+          // We can remove this proxy middle-man once the VFS is working
+          ? callee.argcProxy(func, sigN)
+          : func;
+    const pFunc = wasm.installFunction(fProxy, tgt.memberSignature(name, true));
+    tgt[memKey] = pFunc;
+    if(!tgt.ondispose) tgt.ondispose = [];
+    if(!tgt.ondispose.__removeFuncList){
+      tgt.ondispose.push('ondispose.__removeFuncList handler',
+                         callee.removeFuncList);
+      tgt.ondispose.__removeFuncList = [];
+    }
+    tgt.ondispose.__removeFuncList.push(memKey, pFunc);
+    return (n,f)=>callee(tgt, n, f);
+  }/*installMethod*/;
   
   /**
      Impls for the sqlite3_io_methods methods. Maintenance reminder:
@@ -390,10 +453,11 @@ const initOpfsVfs = function(sqlite3){
     vfsSyncWrappers.xSleep = (pVfs,ms)=>opRun('xSleep',ms);
   }
 
-  /*
-    TODO: plug in the above functions in to opfsVfs and opfsIoMethods.
-    Code for doing so is in api/sqlite3-api-opfs.js.
-  */
+  /* Install the vfs/io_methods into their C-level shared instances... */
+  let inst = installMethod(opfsIoMethods);
+  for(let k of Object.keys(ioSyncWrappers)) inst(k, ioSyncWrappers[k]);
+  inst = installMethod(opfsVfs);
+  for(let k of Object.keys(vfsSyncWrappers)) inst(k, vfsSyncWrappers[k]);
   
   const sanityCheck = async function(){
     //state.ioBuf = new Uint8Array(state.sabIo);
@@ -430,10 +494,10 @@ const initOpfsVfs = function(sqlite3){
       rc = ioSyncWrappers.xFileSize(sq3File.pointer, pOut);
       if(rc) toss('xFileSize failed w/ rc',rc);
       log("xFileSize says:",wasm.getMemValue(pOut, 'i64'));
-      rc = ioSyncWrappers.xWrite(sq3File.pointer, zDbFile, 10, 0);
+      rc = ioSyncWrappers.xWrite(sq3File.pointer, zDbFile, 10, 1);
       if(rc) toss("xWrite() failed!");
       const readBuf = wasm.scopedAlloc(16);
-      rc = ioSyncWrappers.xRead(sq3File.pointer, readBuf, 6, 1);
+      rc = ioSyncWrappers.xRead(sq3File.pointer, readBuf, 6, 2);
       wasm.setMemValue(readBuf+6,0);
       let jRead = wasm.cstringToJs(readBuf);
       log("xRead() got:",jRead);
@@ -453,9 +517,8 @@ const initOpfsVfs = function(sqlite3){
     }
   };
 
-  
   W.onmessage = function({data}){
-    log("Worker.onmessage:",data);
+    //log("Worker.onmessage:",data);
     switch(data.type){
         case 'loaded':
           /*Pass our config and shared state on to the async worker.*/
@@ -476,8 +539,9 @@ const initOpfsVfs = function(sqlite3){
             }
             capi.sqlite3_vfs_register.addReference(opfsVfs, opfsIoMethods);
             state.opSABView = new Int32Array(state.opSAB);
-            if(self.location && +self.location.port > 1024){
-              log("Running sanity check for dev mode...");
+
+            if(thisUrl.searchParams.has('opfs-sanity-check')){
+              warn("Running sanity checks because of opfs-sanity-check URL arg...");
               sanityCheck();
             }
             warn("End of (very incomplete) OPFS setup.", opfsVfs);
diff --git a/manifest b/manifest
index b288f12d6c..561605cbab 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Correct\sOPFS\sxRead()\sand\sxWrite()\simpls\sand\sadd\sa\svery\sbasic\ssanity\stest\sfor\sthem.
-D 2022-09-17T23:47:20.619
+C Plug\sOPFS\smethods\sin\sto\stheir\ssqlite3_vfs/io_methods\scounterparts.\sAdd\sURL\sargs\sto\scontrol\sdebug\soutput\sand\srunning\sof\ssanity-checks\sin\sthe\sOPFS\sinit\scode.
+D 2022-09-18T00:16:12.445
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -502,7 +502,7 @@ F ext/wasm/fiddle/emscripten.css 3d253a6fdb8983a2ac983855bfbdd4b6fa1ff267c28d695
 F ext/wasm/fiddle/fiddle-worker.js bccf46045be8824752876f3eec01c223be0616ccac184bffd0024cfe7a3262b8
 F ext/wasm/fiddle/fiddle.html 550c5aafce40bd218de9bf26192749f69f9b10bc379423ecd2e162bcef885c08
 F ext/wasm/fiddle/fiddle.js 4ffcfc9a235beebaddec689a549e9e0dfad6dca5c1f0b41f03468d7e76480686
-F ext/wasm/index.html 8365e47e2aff1829923f0481292948487b27a0755fde9c0d3ad15f7ea0118992
+F ext/wasm/index.html b8a47afa96d0c7ac3081c6d469e1fd7be6b87c64b94e4fb62e26984a1564cac4
 F ext/wasm/jaccwabyt/jaccwabyt.js 0d7f32817456a0f3937fcfd934afeb32154ca33580ab264dab6c285e6dbbd215
 F ext/wasm/jaccwabyt/jaccwabyt.md 447cc02b598f7792edaa8ae6853a7847b8178a18ed356afacbdbf312b2588106
 F ext/wasm/jaccwabyt/jaccwabyt_test.c 39e4b865a33548f943e2eb9dd0dc8d619a80de05d5300668e9960fff30d0d36f
@@ -533,8 +533,8 @@ F ext/wasm/testing1.js 7cd8ab255c238b030d928755ae8e91e7d90a12f2ae601b1b8f7827aaa
 F ext/wasm/testing2.html a66951c38137ff1d687df79466351f3c734fa9c6d9cce71d3cf97c291b2167e3
 F ext/wasm/testing2.js 25584bcc30f19673ce13a6f301f89f8820a59dfe044e0c4f2913941f4097fe3c
 F ext/wasm/wasmfs.make 21a5cf297954a689e0dc2a95299ae158f681cae5e90c10b99d986097815fd42d
-F ext/wasm/x-sync-async.html 717b0d3bee96e49cbd36731bead497ab27a8bf3a3b23dd11e40e61d4ac9e8b80
-F ext/wasm/x-sync-async.js 961eb6c268086babd20d7b5e07cad72dc3118f9c46954e9a73b8b826deb4f771
+F ext/wasm/x-sync-async.html d85cb9b1ab398ef5a20ce64a689ce4bf9a347ffe69edd46c2d3dc57b869a8925
+F ext/wasm/x-sync-async.js 2cd04d73ddc515479cc2e4b9246d6da21b3f494020261d47470f4b710c84c0da
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
 F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
 F magic.txt 8273bf49ba3b0c8559cb2774495390c31fd61c60
@@ -2030,8 +2030,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P c342b5d745f301104c59851c753287ebbbe95a69a56cb522d376d0f3e352c30f
-R 70b6b0622f3dd6730d580a81783f068d
+P cd06cc670029763955cf60ffcf944b36d41cb005b859d9b9fd0eea1b6741d0e9
+R af48df928e44c11df9f0c9eb2cf8376e
 U stephan
-Z 5c4a37b98dc31ffc6cd63d317f5738d7
+Z 07b2e0eb2359d701cc905c5402ed9c24
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 39390f941c..274fb7f0c1 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-cd06cc670029763955cf60ffcf944b36d41cb005b859d9b9fd0eea1b6741d0e9
\ No newline at end of file
+a0e93ed20b2463606a63b03ce8ca41ec1fb22886db5c5c898ace86ba24636f70
\ No newline at end of file