test: verify portable workspace registry end to end

backend/src/workspaces/registry.ts

@@ -1,6 +1,6 @@
 import { createHash, randomUUID } from "node:crypto";
 import { lstatSync } from "node:fs";
-import { mkdir, readFile, rename, rm, writeFile } from "node:fs/promises";
+import { mkdir, readdir, readFile, rename, rm, writeFile } from "node:fs/promises";
 import { isAbsolute, join } from "node:path";
 import { buildInstallationContract, renderWorkspaceDocs } from "./contracts.js";
 import {
@@ -164,6 +164,30 @@ export class WorkspaceRegistry {
     }
   }
 
+  /**
+   * Garbage-collect obsolete immutable snapshots without breaking cold Resume.
+   * Callers must supply revisions collected from an administrator-visible complete session list;
+   * a partial, per-user list could otherwise remove another user's resumable workspace pin.
+   */
+  async reconcileSnapshotRetention(referencedCommits: readonly string[]): Promise<void> {
+    const retained = new Set(referencedCommits.map(safeCommit));
+    await this.repository.ensureLayout();
+    await this.lock.run(async () => {
+      retained.add((await this.activeState()).head);
+      const entries = await readdir(this.repository.snapshotsPath, { withFileTypes: true });
+      for (const entry of entries) {
+        // Leave staging and unexpected entries untouched: this cleanup only owns finalized,
+        // commit-addressed snapshot directories.
+        if (!entry.isDirectory() || entry.isSymbolicLink() || !/^[0-9a-f]{40}$/.test(entry.name)) continue;
+        if (retained.has(entry.name)) continue;
+        const path = join(this.repository.snapshotsPath, entry.name);
+        const current = lstatSync(path);
+        if (!current.isDirectory() || current.isSymbolicLink()) continue;
+        await rm(path, { recursive: true, force: true });
+      }
+    });
+  }
+
   /**
    * Publish canonical YAML and derived public documentation as one optimistic Git revision.
    * The browser never provides paths or generated artifacts; those are derived server-side.