fix: prevent false cwd split that hides all sessions

Sessions without the cwd field (older JSONL format) were creating a
separate subproject group, even when all sessions with cwd shared the
same value. The orphan subproject got a relative fallback path that
failed git identity resolution, causing zero sessions to load on select.

Now only counts distinct real cwds when deciding whether to split,
treating cwd-less sessions as belonging to the same project.

src/main/services/discovery/ProjectScanner.ts

@@ -267,8 +267,11 @@ export class ProjectScanner {
         cwdGroups.set(key, group);
       }
 
-      // If only 1 unique cwd, return single project (current behavior)
-      if (cwdGroups.size <= 1) {
+      // If only 1 unique real cwd, return single project (current behavior)
+      // Sessions without cwd (older format) are implicitly from the same project,
+      // so we only count distinct real cwds to decide whether to split.
+      const realCwdKeys = [...cwdGroups.keys()].filter((k) => !k.startsWith('__decoded__'));
+      if (realCwdKeys.length <= 1) {
         const allSessionIds = sessionInfos.map((s) => s.sessionId);
         let mostRecentSession: number | undefined;
         let createdAt = Date.now();

test/main/services/discovery/ProjectScanner.cwdSplit.test.ts

@@ -0,0 +1,105 @@
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+import { afterEach, describe, expect, it } from 'vitest';
+
+import { ProjectScanner } from '../../../../src/main/services/discovery/ProjectScanner';
+import { subprojectRegistry } from '../../../../src/main/services/discovery/SubprojectRegistry';
+
+function createSessionLine(opts: { cwd?: string; type?: string }): string {
+  return JSON.stringify({
+    uuid: 'test-uuid',
+    type: opts.type ?? 'user',
+    ...(opts.cwd ? { cwd: opts.cwd } : {}),
+    message: { role: 'user', content: 'hello' },
+    timestamp: new Date().toISOString(),
+  });
+}
+
+describe('ProjectScanner cwd split logic', () => {
+  const tempDirs: string[] = [];
+
+  afterEach(async () => {
+    subprojectRegistry.clear();
+    await new Promise((resolve) => setTimeout(resolve, 50));
+    for (const dir of tempDirs) {
+      try {
+        fs.rmSync(dir, { recursive: true, force: true, maxRetries: 5, retryDelay: 200 });
+      } catch {
+        // Ignore cleanup failures
+      }
+    }
+    tempDirs.length = 0;
+  });
+
+  it('does not split when sessions have a single cwd mixed with sessions without cwd', async () => {
+    const projectsDir = fs.mkdtempSync(path.join(os.tmpdir(), 'scanner-'));
+    tempDirs.push(projectsDir);
+
+    // Create a project directory with encoded name
+    const encodedName = '-Users-test-myproject';
+    const projectDir = path.join(projectsDir, encodedName);
+    fs.mkdirSync(projectDir);
+
+    // Session WITH cwd
+    fs.writeFileSync(
+      path.join(projectDir, 'session-with-cwd.jsonl'),
+      createSessionLine({ cwd: '/Users/test/myproject' }) + '\n'
+    );
+
+    // Session WITHOUT cwd (older format)
+    fs.writeFileSync(
+      path.join(projectDir, 'session-no-cwd.jsonl'),
+      createSessionLine({ type: 'system' }) +
+        '\n' +
+        createSessionLine({ type: 'user' }) +
+        '\n'
+    );
+
+    const scanner = new ProjectScanner(projectsDir);
+    const projects = await scanner.scan();
+
+    // Should produce 1 project, not 2 subprojects
+    const myProjects = projects.filter((p) => p.id.includes('myproject'));
+    expect(myProjects).toHaveLength(1);
+
+    // Should use the plain encoded name, not a composite ID
+    expect(myProjects[0].id).toBe(encodedName);
+
+    // Should include both sessions
+    expect(myProjects[0].sessions).toHaveLength(2);
+  });
+
+  it('splits when sessions have multiple distinct cwds', async () => {
+    const projectsDir = fs.mkdtempSync(path.join(os.tmpdir(), 'scanner-'));
+    tempDirs.push(projectsDir);
+
+    const encodedName = '-Users-test-myproject';
+    const projectDir = path.join(projectsDir, encodedName);
+    fs.mkdirSync(projectDir);
+
+    // Session with cwd A
+    fs.writeFileSync(
+      path.join(projectDir, 'session-a.jsonl'),
+      createSessionLine({ cwd: '/Users/test/myproject' }) + '\n'
+    );
+
+    // Session with cwd B (different)
+    fs.writeFileSync(
+      path.join(projectDir, 'session-b.jsonl'),
+      createSessionLine({ cwd: '/Users/test/other-project' }) + '\n'
+    );
+
+    const scanner = new ProjectScanner(projectsDir);
+    const projects = await scanner.scan();
+
+    // Should produce 2 subprojects with composite IDs
+    const myProjects = projects.filter((p) => p.id.includes('myproject'));
+    expect(myProjects).toHaveLength(2);
+
+    // Both should be composite IDs
+    for (const proj of myProjects) {
+      expect(proj.id).toContain('::');
+    }
+  });
+});