diff --git a/CONTRIBUTING.Sharkey.md b/CONTRIBUTING.Sharkey.md
index 943fd8688d..b20a3fdf9b 100644
--- a/CONTRIBUTING.Sharkey.md
+++ b/CONTRIBUTING.Sharkey.md
@@ -326,11 +326,14 @@ git checkout -m merge/$(date +%Y-%m-%d)   # Create/switch to a merge branch for
 git merge --no-ff misskey/develop   # Merge from Misskey's develop branch, forcing a merge commit.
 ```
 
-Fix conflicts and *commit!* Conflicts in `pnpm-lock.yaml` can usually
-be fixed by running `pnpm install` - it detects conflict markers and
-seems to do a decent job.
+Fix conflicts and *commit!*
+- Conflicts in `pnpm-lock.yaml` can be fixed by rejecting changes and running `pnpm install`.
+- Conflicts in `packages/misskey-js/etc` and `packages/misskey-js/src/autogen` can be fixed by rejecting changes and running `pnpm run build-misskey-js-with-types`.
+- Conflicts in `locales/index.d.ts` can be fixed by rejecting changes and running `pnpm run build-assets`.
+- Conflicts in any `package.json` file can be fixed by merging only added/removed dependencies, then running `pnpm run sync-dependency-versions`. Other changes (not dependencies) will need to be merged manually.
+- Conflicts involving `this.timeService.now` or `this.timeService.date` can be resolved by accepting remote changes. ESLint will highlight all the missing references in a later step.
 
-*After that commit,* do all the extra work, on the same branch:
+*After that commit*, do all the extra work on the same branch:
 
 - Copy all changes (commit after each step):
     - in `packages/backend/src/core/activitypub/models/ApNoteService.ts`, from `createNote` to `updateNote`
diff --git a/package.json b/package.json
index 4d5b83a6c9..05ef62da35 100644
--- a/package.json
+++ b/package.json
@@ -47,7 +47,8 @@
 		"test-and-coverage": "pnpm -r test-and-coverage",
 		"clean": "node ./scripts/clean.js",
 		"clean-all": "node ./scripts/clean-all.js",
-		"cleanall": "pnpm clean-all"
+		"cleanall": "pnpm clean-all",
+		"sync-dependency-versions": "node scripts/sync-deps.mjs"
 	},
 	"resolutions": {
 		"chokidar": "4.0.3",
diff --git a/scripts/sync-deps.mjs b/scripts/sync-deps.mjs
new file mode 100644
index 0000000000..b1f6515076
--- /dev/null
+++ b/scripts/sync-deps.mjs
@@ -0,0 +1,390 @@
+/*
+ * SPDX-FileCopyrightText: hazelnoot and other Sharkey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import nodePath from 'node:path';
+import nodeFs from 'node:fs/promises';
+
+/**
+ * Root directory of the repository.
+ * @type {string}
+ */
+const rootDir = nodePath.resolve(import.meta.dirname, '..');
+
+/**
+ * Filename patterns to exclude.
+ * @type {RegExp[]}
+ */
+const excludedPaths = [
+	/\/node_modules\//,
+	/\/(js_)?built\//i,
+	/\/temp\//i,
+];
+
+/**
+ * All packages located in the solution
+ */
+const packages = await loadPackages();
+
+/**
+ * All packages defined in the solution
+ */
+const dependencies = mapDependencies(packages);
+const allDependencies = Object.values(dependencies);
+const allDependenciesWithDifference = allDependencies.filter(d => d.hasDifference);
+
+console.log(`Found ${allDependenciesWithDifference.length} mismatched dependencies (out of ${allDependencies.length} total) from ${packages.length} packages.`);
+
+if (allDependenciesWithDifference.length > 0) {
+	await syncDependencies(allDependenciesWithDifference);
+	console.log(`package.json files have changed. Please run "pnpm i" to update the pnpm-lock.yaml, then verify that everything still works.`);
+}
+
+async function loadPackages() {
+	/**
+	 * @type {Package[]}
+	 */
+	let packages = [];
+
+	/**
+	 * @param {string} dir
+	 * @returns {Promise<void>}
+	 */
+	const loadPackagesFrom = async (dir) => {
+		const files = await nodeFs.readdir(dir, { withFileTypes: true });
+
+		for (const entry of files) {
+			const path = nodePath.join(dir, entry.name);
+
+			// Check for filtered paths
+			let filterPath = path.replaceAll(nodePath.sep, '/');
+			if (entry.isDirectory()) {
+				filterPath += '/';
+			}
+			if (excludedPaths.some(p => p.test(filterPath))) {
+				//console.debug(`Skipping excluded path ${path}`);
+				continue;
+			}
+
+			if (entry.isDirectory()) {
+				await loadPackagesFrom(path);
+				continue;
+			}
+
+			if (entry.isFile() && entry.name === 'package.json') {
+				try {
+					const packageText = await nodeFs.readFile(path, { encoding: 'utf-8' });
+					const packageJson = JSON.parse(packageText);
+
+					// Handle duplicate package names
+					let packageName = packageJson.name || nodePath.basename(dir);
+					if (packages.some(p => p.name === packageName)) {
+						let i = 1;
+						while (packages.some(p => p.name === `${packageName}:${i}`) ){
+							i++;
+						}
+						packageName = `${packageName}:${i}`;
+					}
+
+					// Parse and flatten all dependency sections
+					const dependencies = mergeDependencies(packageName, {
+						resolutions: parseDependencies(packageName, packageJson, 'resolutions'),
+						peerDependencies: parseDependencies(packageName, packageJson, 'peerDependencies'),
+						optionalDependencies: parseDependencies(packageName, packageJson, 'optionalDependencies'),
+						devDependencies: parseDependencies(packageName, packageJson, 'devDependencies'),
+						dependencies: parseDependencies(packageName, packageJson, 'dependencies'),
+					});
+
+					packages.push({
+						name: packageName,
+						json: packageJson,
+						path,
+						dependencies,
+					});
+
+					if (dependencies.length > 0) {
+						console.info(`Loaded ${dependencies.length} dependencies from ${packageName}`);
+					} else {
+						// console.debug(`Loaded no dependencies from ${packageName}`);
+					}
+				} catch (err) {
+					console.warn(`Error reading package from ${path}:`, err);
+				}
+			}
+		}
+	};
+
+
+	await loadPackagesFrom(rootDir);
+	return packages;
+}
+
+/**
+ * @param {string} packageName
+ * @param {Record<DepType, Dependency[]>} dependencyGroups
+ * @returns {Dependency[]}
+ */
+function mergeDependencies(packageName, dependencyGroups) {
+	/** @type {Dependency[]} */
+	const dependencies = [];
+
+	for (const type of Object.keys(dependencyGroups)) {
+		/** @type {Dependency[]} */
+		const typeDependencies = dependencyGroups[type];
+		for (const dependency of typeDependencies) {
+			const existing = dependencies.find(d => d.name === dependency.name);
+			if (existing) {
+				console.warn(`[${packageName}/${type}/${dependency.name}] Skipping duplicate dependency (was already defined in ${existing.type})`);
+			} else {
+				dependencies.push(dependency);
+			}
+		}
+	}
+
+	return dependencies;
+}
+
+/**
+ * @param {string} packageName
+ * @param {Record<DepType, unknown>} packageJson
+ * @param {DepType} type
+ * @returns {Dependency[]}
+ */
+function parseDependencies(packageName, packageJson, type) {
+	/** @type {Dependency[]} */
+	const dependencies = [];
+
+	// Make sure we actually have this type
+	if (typeof(packageJson[type]) === 'object') {
+		for (const [name, npmVersion] of Object.entries(packageJson[type])) {
+			const version = parseVersionString(packageName, type, name, npmVersion);
+			if (version != null) {
+				dependencies.push({
+					name,
+					type,
+					version,
+					npmVersion,
+				});
+			}
+		}
+	}
+
+	return dependencies;
+}
+
+/**
+ * @param {string} packageName
+ * @param {DepType} depType
+ * @param {string} depName
+ * @param {unknown} versionString
+ * @returns {DepVersion | null}
+ */
+function parseVersionString(packageName, depType, depName, versionString) {
+	if (typeof(versionString) !== 'string') {
+		console.warn(`[${packageName}/${depType}/${depName}] Skipping version string "${versionString}" - incorrect type ${typeof(versionString)}`);
+		return null;
+	}
+
+	if (versionString.startsWith('npm:') || versionString.startsWith('workspace:')) {
+		//console.warn(`[${packageName}/${depType}/${depName}] Skipping version string "${versionString}" - package redirects are not supported`);
+		return null;
+	}
+
+	if (versionString.startsWith('github:') || versionString.startsWith('http:') || versionString.startsWith('https:')) {
+		//console.warn(`[${packageName}/${depType}/${depName}] Skipping version string "${versionString}" - external packages are not supported`);
+		return null;
+	}
+
+	if (versionString === '') {
+		versionString = '*';
+	} else if (versionString === 'latest') {
+		versionString = '*';
+	} else if (versionString === 'next') {
+		versionString = '*';
+	} else {
+		versionString = versionString.replaceAll(/(\b|^)[x*]+(\b|$)/g, '*');
+	}
+
+	const versionMatch = versionString.match(/^([\^<>~=]*)((\d+|\*)(\.(\d+|\*)+)*)(\b|$|[-+])/);
+	if (!versionMatch) {
+		console.warn(`[${packageName}/${depType}/${depName}] Skipping version string "${versionString}" - not in a parseable format`);
+		return null;
+	}
+
+	const upgradePrefix = versionMatch[1];
+	const primaryVersion = versionMatch[2];
+
+	// Parse the primary version (x.y.z)
+	/** @type {DepVersion} */
+	const parsedVersion = primaryVersion
+		.split('.')
+		.map(p => p === '*' ? '*' : parseInt(p));
+
+	// Parse the upgrade prefix
+	if (upgradePrefix === '>' || upgradePrefix === '>=') {
+		parsedVersion.push('*');
+	} else if (upgradePrefix === '~') {
+		// "Allows patch-level changes if a minor version is specified on the comparator. Allows minor-level changes if not."
+		// https://github.com/npm/node-semver#versions
+		const start = parsedVersion.length > 2 ? 2 : 1;
+		for (let i = start; i < parsedVersion.length; i++) {
+			parsedVersion[i] = '*';
+		}
+	} else if (upgradePrefix === '^') {
+		// "Allows changes that do not modify the left-most non-zero element in the [major, minor, patch] tuple."
+		// https://github.com/npm/node-semver#versions
+		for (let i = 1; i < parsedVersion.length; i++) {
+			parsedVersion[i] = '*';
+		}
+	}
+
+	// Collapse x.*.z to just x.*
+	const firstStarIdx = parsedVersion.indexOf('*');
+	if (firstStarIdx >= 0) {
+		parsedVersion.length = firstStarIdx + 1;
+	}
+
+	return parsedVersion;
+}
+
+/**
+ * @param {Package[]} packages
+ * @returns {Partial<Record<string, MappedDependency>>}
+ */
+function mapDependencies(packages) {
+	/** @type {Partial<Record<string, MappedDependency>>} */
+	const mappedDependencies = {};
+
+	for (const pkg of packages) {
+		for (const dependency of pkg.dependencies) {
+			const packageDependency = { package: pkg, packageDependency: dependency };
+
+			/** @type {MappedDependency} */
+			let mapping = mappedDependencies[dependency.name];
+			if (!mapping) {
+				mapping = {
+					name: dependency.name,
+					newestVersion: dependency.version,
+					newestNpmVersion: dependency.npmVersion,
+					hasDifference: false,
+					packages: [packageDependency],
+				};
+				mappedDependencies[dependency.name] = mapping;
+			} else {
+				if (isNewer(dependency.version, mapping.newestVersion)) {
+					mapping.newestVersion = dependency.version;
+					mapping.newestNpmVersion = dependency.npmVersion;
+					mapping.hasDifference = true;
+				}
+				mapping.packages.push(packageDependency);
+			}
+		}
+	}
+
+	return mappedDependencies;
+}
+
+/**
+ * @param {DepVersion} a
+ * @param {DepVersion} b
+ * @return {boolean}
+ */
+function isNewer(a, b) {
+	return compareVersions(a, b) > 0;
+}
+
+/**
+ * -1 => a is older / b is newer
+ * 0 => same age
+ * 1 => a is newer / b is older
+ * @param {DepVersion} a
+ * @param {DepVersion} b
+ * @return {-1 | 0 | 1}
+ */
+function compareVersions(a, b) {
+	const limit = Math.max(a.length, b.length);
+
+	// Check each part (x.y.z and so on)
+	for (let i = 0; i < limit; i++) {
+		const aPart = a[i] ?? '*';
+		const bPart = b[i] ?? '*';
+
+		if (aPart === '*') {
+			if (bPart !== '*') {
+				// A matches any and B has a limit, therefore A is newer
+				return 1;
+			}
+		} else if (bPart === '*') {
+			// A has a limit and B matches any, therefore B is newer
+			return -1;
+		} else if (aPart !== bPart) {
+			if (aPart > bPart) {
+				// A has a limit and B has a lower limit, therefore A is newer
+				return 1;
+			} else {
+				// A has a limit and B has a higher limit, therefore B is newer
+				return -1;
+			}
+		}
+	}
+
+	// If parseable versions match, then consider them the same.
+	return 0;
+}
+
+/**
+ * @param {MappedDependency[]} dependencies
+ * @returns {Promise<void>}
+ */
+async function syncDependencies(dependencies) {
+	/** @type {Partial<Record<string, Package>>} */
+	const modifiedPackages = {};
+
+	for (const dependency of dependencies) {
+		for (const pkg of dependency.packages) {
+			if (dependency.newestNpmVersion !== pkg.packageDependency.npmVersion) {
+				console.log(`Updating ${dependency.name} from version ${pkg.packageDependency.npmVersion} to ${dependency.newestNpmVersion} in package ${pkg.package.name}`);
+				pkg.package.json[pkg.packageDependency.type][dependency.name] = dependency.newestNpmVersion;
+				modifiedPackages[pkg.package.name] = pkg.package;
+			}
+		}
+	}
+
+	for (const pkg of Object.values(modifiedPackages)) {
+		const packageText = JSON.stringify(pkg.json, null, '\t');
+		await nodeFs.writeFile(pkg.path, packageText, 'utf-8');
+	}
+}
+
+/**
+ * @typedef Package
+ * @property {string} name
+ * @property {string} path
+ * @property {object} json
+ * @property {Dependency[]} dependencies
+ */
+
+/**
+ * @typedef Dependency
+ * @property {string} name
+ * @property {DepType} type
+ * @property {DepVersion} version
+ * @property {string} npmVersion
+ */
+
+/**
+ * @typedef {'dependencies' | 'devDependencies' | 'optionalDependencies' | 'peerDependencies' | 'resolutions'} DepType
+ * @typedef {[DepPart, ...DepPart[]][]} DepVersion
+ * @typedef {number | '*'} DepPart
+ */
+
+/**
+ * @typedef MappedDependency
+ * @property {string} name
+ * @property {DepVersion} newestVersion
+ * @property {string} newestNpmVersion
+ * @property {boolean} hasDifference
+ * @property {{package: Package, packageDependency: Dependency}[]} packages
+ */
+