fix(dev): source watcher ignores the package build's .compile- scratch dir (red main)

.changeset/watcher-compile-scratch.md

@@ -0,0 +1,5 @@
+---
+"agent-bundle": patch
+---
+
+Ignore the package build's `.<output>.compile-XXXXXX` scratch directory in the `agent-bundle dev` source watcher, so a `dist/` package build no longer republishes the epoch it just produced and Workbench invocations run under the epoch that was active when they were queued. (#669)

packages/agent-bundle/src/dev/watcher.ts

@@ -37,14 +37,15 @@ const relativePath = (root: string, path: string): string | undefined => {
  * Whether `source` is inside the staging directory an output root is
  * assembled in: the package build (`package-build.ts`) and the artifact
  * build (`build.ts`) `mkdtemp` a `.<output>.stage-XXXXXX` sibling of the
- * output root and rename it into place, so those paths are build output
- * too, not source. Without this, every `dist/` package build inside
+ * output root and rename it into place, and the package build compiles in a
+ * `.<output>.compile-XXXXXX` sibling first (#656), so those paths are build
+ * output too, not source. Without this, every `dist/` package build inside
  * `agent-bundle dev` would invalidate the epoch it just produced.
  */
 const isOutputStagingPath = (output: string, source: string): boolean => {
   const parent = dirname(output);
-  const prefix = `${parent === '.' ? '' : `${parent}/`}.${basename(output)}.stage-`;
-  return source.startsWith(prefix);
+  const prefix = `${parent === '.' ? '' : `${parent}/`}.${basename(output)}.`;
+  return source.startsWith(`${prefix}stage-`) || source.startsWith(`${prefix}compile-`);
 };
 
 const defaultPathSignature = async (path: string): Promise<string | undefined> => {

packages/agent-bundle/tests/dev-watcher.test.ts

@@ -71,6 +71,10 @@ it('debounces only relevant source paths into one ordered invalidation and close
   // renaming it into place; that staging tree is output, not source.
   fake.emit('addDir', '/project with spaces/.dist.stage-W3rHAr');
   fake.emit('add', '/project with spaces/.dist.stage-W3rHAr/bin/plugin.js');
+  // ... and compiles into a `.dist.compile-XXXXXX` sibling first (#656).
+  fake.emit('addDir', '/project with spaces/.dist.compile-Qm2xLp');
+  fake.emit('add', '/project with spaces/.dist.compile-Qm2xLp/bin/plugin.js');
+  fake.emit('unlinkDir', '/project with spaces/.dist.compile-Qm2xLp');
   fake.emit('add', '/project with spaces/.distinct-source.ts');
   await watcher.flush();