fix flaky resume behavior

tests/progress-multiprd.test.ts

@@ -0,0 +1,82 @@
+/// <reference types="bun-types" />
+import { describe, it, expect, beforeEach } from "bun:test";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import { ProgressTracker } from "../src/progress";
+
+/**
+ * Regression test: two concurrent loops (different PRDs) each run their own
+ * ProgressTracker. Each instance snapshots the whole state at construction;
+ * a save() that writes that stale snapshot verbatim would revert the OTHER
+ * loop's task status changes — tasks wrongly back to "pending" while their
+ * worktrees carry real work, stranding it on the next resume.
+ */
+let root: string;
+
+beforeEach(() => {
+	root = fs.mkdtempSync(path.join(os.tmpdir(), "ralpi-prog-test-"));
+});
+
+function prdA(projectDir: string): ProgressTracker {
+	return new ProgressTracker(
+		projectDir,
+		path.join(projectDir, "tasks/a/README.md"),
+	);
+}
+function prdB(projectDir: string): ProgressTracker {
+	return new ProgressTracker(
+		projectDir,
+		path.join(projectDir, "tasks/b/README.md"),
+	);
+}
+
+/** Read the on-disk progress state; the file is written by the tracker, so
+ *  a parse failure is a test bug worth surfacing. */
+function readState(): Record<string, any> {
+	const raw = fs.readFileSync(
+		path.join(root, ".ralpi", "progress.json"),
+		"utf-8",
+	);
+	try {
+		return JSON.parse(raw) as Record<string, any>;
+	} catch {
+		throw new Error(`malformed progress.json:\n${raw.slice(0, 200)}`);
+	}
+}
+
+describe("ProgressTracker multi-PRD save isolation", () => {
+	it("does not clobber another PRD's task status on save", () => {
+		const a = prdA(root);
+		const b = prdB(root);
+		expect(a.getKey()).not.toBe(b.getKey());
+
+		// Loop A marks its task in_progress.
+		a.markInProgress("01");
+		expect(a.getTaskStatus("01")).toBe("in_progress");
+
+		// Loop B (stale snapshot from before A's update) marks ITS task.
+		b.markInProgress("02");
+
+		// The on-disk state must show BOTH updates.
+		const raw = readState();
+		expect(raw.prds[a.getKey()].tasks["01"].status).toBe("in_progress");
+		expect(raw.prds[b.getKey()].tasks["02"].status).toBe("in_progress");
+	});
+
+	it("preserves other PRD completions when this PRD saves", () => {
+		const a = prdA(root);
+		const b = prdB(root);
+
+		a.markCompleted("01", 1000);
+		b.markInProgress("02");
+
+		// A completes another task later — A's save must not revert B.
+		a.markCompleted("03", 500);
+
+		const raw = readState();
+		expect(raw.prds[a.getKey()].tasks["01"].status).toBe("completed");
+		expect(raw.prds[a.getKey()].tasks["03"].status).toBe("completed");
+		expect(raw.prds[b.getKey()].tasks["02"].status).toBe("in_progress");
+	});
+});