diff --git a/implementations/javascript/packages/schema/package.json b/implementations/javascript/packages/schema/package.json
index 16ddcf4..f646854 100644
--- a/implementations/javascript/packages/schema/package.json
+++ b/implementations/javascript/packages/schema/package.json
@@ -13,7 +13,7 @@
   "types": "lib/index.d.ts",
   "author": "Tony Garnock-Jones <tonyg@leastfixedpoint.com>",
   "scripts": {
-    "regenerate": "rm -rf ./src/gen && ./bin/preserves-schema-ts.js --output ./src/gen ../../../../schema/schema.prs",
+    "regenerate": "rm -rf ./src/gen && ./bin/preserves-schema-ts.js --output ./src/gen ../../../../schema:schema.prs",
     "clean": "rm -rf lib dist",
     "prepare": "tsc && rollup -c",
     "rollupwatch": "rollup -c -w",
diff --git a/implementations/javascript/packages/schema/src/bin/cli-utils.ts b/implementations/javascript/packages/schema/src/bin/cli-utils.ts
index abbc1bb..97a8939 100644
--- a/implementations/javascript/packages/schema/src/bin/cli-utils.ts
+++ b/implementations/javascript/packages/schema/src/bin/cli-utils.ts
@@ -1,7 +1,7 @@
 import fs from 'fs';
 import path from 'path';
 import { glob } from 'glob';
-import { formatPosition, Position } from '@preserves/core';
+import { IdentitySet, formatPosition, Position } from '@preserves/core';
 import { readSchema } from '../reader';
 import chalk from 'chalk';
 import * as M from '../meta';
@@ -13,6 +13,7 @@ export interface Diagnostic {
 };
 
 export type InputFile = {
+    inputBaseDir: string,
     inputFilePath: string,
     text: string,
     baseRelPath: string,
@@ -28,7 +29,7 @@ export type XrefFile = {
 };
 
 export type Expanded = {
-    base: string,
+    baseDirs: Array<string>,
     inputFiles: Array<InputFile>,
     xrefFiles: Array<XrefFile>,
     failures: Array<Diagnostic>,
@@ -54,18 +55,29 @@ export function computeBase(paths: string[]): string {
     }
 }
 
-export function expandInputGlob(
-    input: string[],
-    xrefs: string[],
-    base0: string | undefined,
-): Expanded {
-    const matches = input.flatMap(i => glob.sync(i));
+export function findSchemas(userInput: string): ({
+    names: string[],
+    base: string,
+}) {
+    const colonPos = userInput.lastIndexOf(':');
+    let [base, g] = (colonPos === -1)
+        ? [userInput, '**/*.prs']
+        : [userInput.slice(0, colonPos), userInput.slice(colonPos + 1)];
+    if (base[base.length - 1] !== '/') {
+        base = base + '/';
+    }
+    const names = glob.sync(base + g);
+    return { names, base };
+}
+
+export function expandInputGlob(input: string[], xrefs: string[]): Expanded {
     const failures: Array<Diagnostic> = [];
+    const baseDirs = new IdentitySet<string>();
 
     function processInputFile(base: string, filePath: string, xref: true): XrefFile[];
     function processInputFile(base: string, filePath: string, xref: false): InputFile[];
     function processInputFile(base: string, filePath: string, xref: boolean): (InputFile | XrefFile)[] {
-        if (!xref && !filePath.startsWith(base)) {
+        if (!filePath.startsWith(base)) {
             throw new Error(`Input filename ${filePath} falls outside base ${base}`);
         }
         try {
@@ -83,7 +95,7 @@ export function expandInputGlob(
             if (xref) {
                 return [{ xrefFilePath: filePath, text, modulePath, schema }];
             } else {
-                return [{ inputFilePath: filePath, text, baseRelPath, modulePath, schema }];
+                return [{ inputBaseDir: base, inputFilePath: filePath, text, baseRelPath, modulePath, schema }];
             }
         } catch (e) {
             failures.push({ type: 'error', file: filePath, detail: e as Error });
@@ -91,16 +103,22 @@ export function expandInputGlob(
         }
     }
 
-    const base = base0 ?? computeBase(matches);
+    const inputFiles = input.flatMap(userInput => {
+        const { names, base } = findSchemas(userInput);
+        baseDirs.add(base);
+        return names.flatMap(f => processInputFile(base, f, false));
+    });
+
+    const xrefFiles = xrefs.flatMap(userInput => {
+        const { names, base } = findSchemas(userInput);
+        baseDirs.add(base);
+        return names.flatMap(f => processInputFile(base, f, true));
+    });
 
     return {
-        base,
-        inputFiles: matches.flatMap(f => processInputFile(base, f, false)),
-        xrefFiles: xrefs.flatMap(i => {
-            const names = glob.sync(i);
-            const base = computeBase(names);
-            return names.flatMap(f => processInputFile(base, f, true));
-        }),
+        baseDirs: Array.from(baseDirs),
+        inputFiles,
+        xrefFiles,
         failures,
     };
 }
diff --git a/implementations/javascript/packages/schema/src/bin/preserves-schema-ts.ts b/implementations/javascript/packages/schema/src/bin/preserves-schema-ts.ts
index bfb5d74..8289e83 100644
--- a/implementations/javascript/packages/schema/src/bin/preserves-schema-ts.ts
+++ b/implementations/javascript/packages/schema/src/bin/preserves-schema-ts.ts
@@ -13,7 +13,7 @@ export type CommandLineArguments = {
     inputs: string[];
     xrefs: string[];
     base: string | undefined;
-    output: string | undefined;
+    output: string;
     stdout: boolean;
     core: string;
     watch: boolean;
@@ -25,11 +25,11 @@ export type CompilationResult = {
     options: CommandLineArguments,
     inputFiles: Array<TranslatedFile>,
     failures: Array<Diagnostic>,
-    base: string,
-    output: string,
+    baseDirs: Array<string>,
 };
 
 export type TranslatedFile = {
+    inputBaseDir: string,
     inputFilePath: string,
     outputFilePath: string,
     schemaPath: M.ModulePath,
@@ -62,14 +62,18 @@ export function run(options: CommandLineArguments): void {
                 chalk.greenBright('successfully');
             console.log(chalk.gray(new Date().toISOString()) +
                 ` Processed ${r.inputFiles.length} file(s) ${errorSummary}. Waiting for changes.`);
-            const watcher = chokidar.watch(r.base, {
+            let triggered = false;
+            const watchers = r.baseDirs.map(base => chokidar.watch(base, {
                 ignoreInitial: true,
             }).on('all', (_event, filename) => {
                 if (options.inputs.some(i => minimatch(filename, i))) {
-                    watcher.close();
-                    runWatch();
+                    if (!triggered) {
+                        triggered = true;
+                        watchers.map(w => w.close());
+                        runWatch();
+                    }
                 }
-            });
+            }));
         }
         runWatch();
     }
@@ -86,9 +90,8 @@ function isAbsoluteOrExplicitlyRelative(p: string) {
 }
 
 export function runOnce(options: CommandLineArguments): CompilationResult {
-    const { base, failures, inputFiles: inputFiles0, xrefFiles: xrefFiles0 } =
-        expandInputGlob(options.inputs, options.xrefs, options.base);
-    const output = options.output ?? base;
+    const { baseDirs, failures, inputFiles: inputFiles0, xrefFiles: xrefFiles0 } =
+        expandInputGlob(options.inputs, options.xrefs);
 
     let xrefFiles = xrefFiles0; // filtered during construction of extensionEnv
 
@@ -112,9 +115,9 @@ export function runOnce(options: CommandLineArguments): CompilationResult {
     });
 
     const inputFiles: Array<TranslatedFile> = inputFiles0.map(i => {
-        const { inputFilePath, baseRelPath, modulePath, schema } = i;
-        const outputFilePath = path.join(output, changeExt(baseRelPath, '.ts'));
-        return { inputFilePath, outputFilePath, schemaPath: modulePath, schema };
+        const { inputBaseDir, inputFilePath, baseRelPath, modulePath, schema } = i;
+        const outputFilePath = path.join(options.output, changeExt(baseRelPath, '.ts'));
+        return { inputBaseDir, inputFilePath, outputFilePath, schemaPath: modulePath, schema };
     });
 
     inputFiles.forEach(c => {
@@ -164,7 +167,7 @@ export function runOnce(options: CommandLineArguments): CompilationResult {
 
     formatFailures(failures, options.traceback);
 
-    return { options, inputFiles, failures, base, output };
+    return { options, inputFiles, failures, baseDirs };
 }
 
 export function main(argv: Array<string>) {
diff --git a/implementations/javascript/packages/schema/src/bin/preserves-schemac.ts b/implementations/javascript/packages/schema/src/bin/preserves-schemac.ts
index eec9fa2..0c3025f 100644
--- a/implementations/javascript/packages/schema/src/bin/preserves-schemac.ts
+++ b/implementations/javascript/packages/schema/src/bin/preserves-schemac.ts
@@ -7,12 +7,11 @@ import { expandInputGlob, formatFailures } from './cli-utils';
 
 export type CommandLineArguments = {
     inputs: string[];
-    base: string | undefined;
     bundle: boolean;
 };
 
 export function run(options: CommandLineArguments): void {
-    const { failures, inputFiles } = expandInputGlob(options.inputs, [], options.base);
+    const { failures, inputFiles } = expandInputGlob(options.inputs, []);
 
     if (!options.bundle && inputFiles.length !== 1) {
         failures.push({ type: 'error', file: null, detail: {
@@ -41,14 +40,12 @@ export function main(argv: Array<string>) {
     new Command()
         .arguments('[input...]')
         .description('Compile textual Preserves schema definitions to binary format', {
-            input: 'Input filename or glob',
+            input: 'Input directory, with optional ":glob" appended (defaults to ":**/*.prs")',
         })
         .option('--no-bundle', 'Emit a single Schema instead of a schema Bundle')
-        .option('--base <directory>', 'Base directory for sources (default: common prefix)')
         .action((inputs: string[], rawOptions) => {
             const options: CommandLineArguments = {
                 inputs: inputs.map(i => path.normalize(i)),
-                base: rawOptions.base,
                 bundle: rawOptions.bundle,
             };
             Error.stackTraceLimit = Infinity;