refactor(project): Import/overwrite stages from cache after saving

Author: RandomByte

packages/project/lib/build/cache/ProjectBuildCache.js

@@ -365,6 +365,9 @@ export default class ProjectBuildCache {
 
 		await this.#cacheManager.writeBuildManifest(
 			this.#project, this.#buildSignature, buildManifest);
+
+		// Import cached stages back into project to prevent inconsistent state during next build/save
+		await this.#importCachedStages(buildManifest.cache.stages);
 	}
 
 	#getStageNameForTask(taskName) {
@@ -392,7 +395,6 @@ export default class ProjectBuildCache {
 			}));
 			return [stageId, resourceMetadata];
 		}));
-		// Optional TODO: Re-import cache as base layer to reduce memory pressure?
 	}
 
 	async #checkForIndexChanges(index, indexTimestamp) {

packages/project/lib/specifications/Project.js

@@ -381,6 +381,16 @@ class Project extends Specification {
 		this.#currentStageWorkspace = null;
 	}
 
+	_resetStages() {
+		this.#stages = [];
+		this.#currentStage = null;
+		this.#currentStageName = "<source>";
+		this.#currentStageReadIndex = -1;
+		this.#currentStageReaders = new Map();
+		this.#currentStageWorkspace = null;
+		this.#workspaceVersion = 0;
+	}
+
 	#getReaderForStage(stage, style = "buildtime", includeCache = true) {
 		const writers = stage.getAllWriters(includeCache);
 		const readers = [];
@@ -406,23 +416,7 @@ class Project extends Specification {
 	}
 
 	setStages(stageIds, cacheReaders) {
-		if (this.#stages.length > 0) {
-			// Stages have already been set. Compare existing stages with new ones and throw on mismatch
-			for (let i = 0; i < stageIds.length; i++) {
-				const stageId = stageIds[i];
-				if (this.#stages[i].getId() !== stageId) {
-					throw new Error(
-						`Unable to set stages for project ${this.getName()}: Stage mismatch at position ${i} ` +
-						`(existing: ${this.#stages[i].getId()}, new: ${stageId})`);
-				}
-			}
-			if (cacheReaders?.length) {
-				throw new Error(
-					`Unable to set stages for project ${this.getName()}: Cache readers can only be set ` +
-					`when stages are created for the first time`);
-			}
-			return; // Stages already set and matching, no further processing needed
-		}
+		this._resetStages(); // Reset current stages and metadata
 		for (let i = 0; i < stageIds.length; i++) {
 			const stageId = stageIds[i];
 			const newStage = new Stage(stageId, cacheReaders?.[i]);