prevent conflic between obsidian sync and headless sync.

src/shims/fs/index.js

@@ -7,6 +7,7 @@ import { createFsWatch } from "./watch.js";
 import { createWatcherClient } from "./watcher-client.js";
 import { createFdOps } from "./fd.js";
 import { constants } from "./constants.js";
+import { registerReadTransform, removeReadTransform } from "./read-transforms.js";
 
 const metadataCache = new MetadataCache();
 const contentCache = new ContentCache();
@@ -43,6 +44,8 @@ export const fsShim = {
   _metadataCache: metadataCache,
   _contentCache: contentCache,
   _watcherClient: watcherClient,
+  _registerReadTransform: registerReadTransform,
+  _removeReadTransform: removeReadTransform,
 
   async _init(basePath) {
     const tree = await transport.fetchTree(basePath);

src/shims/fs/promises.js

@@ -1,5 +1,6 @@
 import { markLocalOp } from "./echo-guard.js";
 import { isInputCachePath, inputCacheGet } from "./input-cache.js";
+import { applyReadTransform } from "./read-transforms.js";
 
 export function createFsPromises(metadataCache, contentCache, transport) {
   return {
@@ -46,60 +47,52 @@ export function createFsPromises(metadataCache, contentCache, transport) {
 
       const wantText = encoding === "utf8" || encoding === "utf-8";
 
+      let result = null;
+
       // Check input cache for files picked via browser file dialogs.
       if (isInputCachePath(path)) {
-        const inputData = inputCacheGet(path);
-
-        if (inputData !== null) {
-          if (wantText) {
-            return typeof inputData === "string"
-              ? inputData
-              : new TextDecoder().decode(inputData);
-          }
-
-          if (typeof inputData === "string") {
-            return new TextEncoder().encode(inputData);
-          }
-
-          return inputData;
-        }
+        result = inputCacheGet(path);
       }
 
-      const meta = metadataCache.get(path);
-      if (meta && meta.type === "directory") {
-        const e = new Error("EISDIR: illegal operation on a directory, read");
-        e.code = "EISDIR";
-        throw e;
-      }
+      if (result === null) {
+        const meta = metadataCache.get(path);
 
-      if (!meta && path) {
-        const e = new Error(
-          `ENOENT: no such file or directory, open '${path}'`,
-        );
-        e.code = "ENOENT";
-        throw e;
-      }
-
-      const cached = contentCache.get(path);
-
-      if (cached !== null) {
-        if (wantText) {
-          return typeof cached === "string"
-            ? cached
-            : new TextDecoder().decode(cached);
+        if (meta && meta.type === "directory") {
+          const e = new Error("EISDIR: illegal operation on a directory, read");
+          e.code = "EISDIR";
+          throw e;
         }
 
-        // binary. ensure we return a proper Uint8Array with .buffer
-        if (typeof cached === "string") {
-          return new TextEncoder().encode(cached);
+        if (!meta && path) {
+          const e = new Error(
+            `ENOENT: no such file or directory, open '${path}'`,
+          );
+          e.code = "ENOENT";
+          throw e;
         }
 
-        return cached;
+        result = contentCache.get(path);
       }
 
-      const data = await transport.readFile(path, encoding);
-      contentCache.set(path, data);
-      return data;
+      if (result === null) {
+        result = await transport.readFile(path, encoding);
+        contentCache.set(path, result);
+      }
+
+      // Apply registered read transforms (e.g., patching synced config files).
+      result = applyReadTransform(path, result);
+
+      if (wantText) {
+        return typeof result === "string"
+          ? result
+          : new TextDecoder().decode(result);
+      }
+
+      if (typeof result === "string") {
+        return new TextEncoder().encode(result);
+      }
+
+      return result;
     },
 
     async writeFile(path, data, encoding) {

src/shims/fs/read-transforms.js

@@ -0,0 +1,49 @@
+// Post-read transforms for specific file paths.
+// Allows patching file content after reading but before returning to the caller.
+// Used to prevent synced config files from activating conflicting features.
+
+const transforms = new Map();
+
+function normalize(p) {
+  return (p || "")
+    .replace(/\\/g, "/")
+    .replace(/^\/+/, "")
+    .replace(/\/+$/, "");
+}
+
+export function registerReadTransform(path, fn) {
+  transforms.set(normalize(path), fn);
+}
+
+export function removeReadTransform(path) {
+  transforms.delete(normalize(path));
+}
+
+export function applyReadTransform(path, data) {
+  const norm = normalize(path);
+  const fn = transforms.get(norm);
+
+  if (!fn) {
+    return data;
+  }
+
+  try {
+    const result = fn(data);
+
+    if (result !== data) {
+      const before = typeof data === "string" ? data : new TextDecoder().decode(data);
+      const after = typeof result === "string" ? result : new TextDecoder().decode(result);
+      console.log(`[shim:fs] Read transform applied: ${norm}`);
+      console.log(`[shim:fs]   before:`, before);
+      console.log(`[shim:fs]   after:`, after);
+    }
+
+    return result;
+  } catch {
+    return data;
+  }
+}
+
+export function hasReadTransform(path) {
+  return transforms.has(normalize(path));
+}

src/shims/fs/sync.js

@@ -1,5 +1,6 @@
 import { markLocalOp } from "./echo-guard.js";
 import { isInputCachePath, inputCacheGet } from "./input-cache.js";
+import { applyReadTransform } from "./read-transforms.js";
 
 export function createFsSync(metadataCache, contentCache, transport) {
   return {
@@ -58,6 +59,8 @@ export function createFsSync(metadataCache, contentCache, transport) {
         encoding = encoding?.encoding;
       }
 
+      const wantText = encoding === "utf8" || encoding === "utf-8";
+
       const meta = metadataCache.get(path);
       if (meta && meta.type === "directory") {
         const e = new Error("EISDIR: illegal operation on a directory, read");
@@ -65,39 +68,37 @@ export function createFsSync(metadataCache, contentCache, transport) {
         throw e;
       }
 
+      let result = null;
+
       // Check input cache for files picked via browser file dialogs.
-      // These never hit the server; they exist only in browser memory.
       if (isInputCachePath(path)) {
         const inputData = inputCacheGet(path);
 
         if (inputData !== null) {
-          if (encoding === "utf8" || encoding === "utf-8") {
-            return typeof inputData === "string"
-              ? inputData
-              : new TextDecoder().decode(inputData);
-          }
-
-          return inputData;
+          result = inputData;
         }
       }
 
-      const cached = contentCache.get(path);
-      if (cached !== null) {
-        if (encoding === "utf8" || encoding === "utf-8") {
-          return typeof cached === "string"
-            ? cached
-            : new TextDecoder().decode(cached);
-        }
-
-        return cached;
+      if (result === null) {
+        result = contentCache.get(path);
       }
 
-      console.warn("[shim:fs] readFileSync cache miss, using sync XHR:", path);
+      if (result === null) {
+        console.warn("[shim:fs] readFileSync cache miss, using sync XHR:", path);
+        result = transport.readFileSync(path, encoding);
+        contentCache.set(path, result);
+      }
 
-      const data = transport.readFileSync(path, encoding);
-      contentCache.set(path, data);
+      // Apply registered read transforms (e.g., patching synced config files).
+      result = applyReadTransform(path, result);
 
-      return data;
+      if (wantText) {
+        return typeof result === "string"
+          ? result
+          : new TextDecoder().decode(result);
+      }
+
+      return result;
     },
 
     writeFileSync(path, data, encoding) {