fix(hub,cli): coerce null session activeAt so resume cannot 500 (#1026)

Legacy rows and inserts left sessions.active_at NULL while SessionSchema
required a number, so CLI GET /cli/sessions/:id failed Zod and resume
surfaced HTTP 500. Persist active_at on insert, harden hub read coerce,
and nullish-transform activeAt in SessionSchema (output stays number).

Fixes #1025

Co-authored-by: Debian <heavygee@oos-linux.in.lockhouse>
Co-authored-by: Cursor <cursoragent@cursor.com>

shared/src/schemas.sessionActiveAt.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, it } from 'vitest'
+import { SessionSchema } from './schemas'
+
+function baseSession(overrides: Record<string, unknown> = {}) {
+    return {
+        id: '11111111-1111-4111-8111-111111111111',
+        namespace: 'default',
+        seq: 0,
+        createdAt: 1_000,
+        updatedAt: 2_000,
+        active: false,
+        activeAt: 1_000,
+        metadata: null,
+        metadataVersion: 0,
+        agentState: null,
+        agentStateVersion: 0,
+        thinking: false,
+        thinkingAt: 0,
+        ...overrides
+    }
+}
+
+describe('SessionSchema activeAt coerce', () => {
+    it('keeps a numeric activeAt unchanged', () => {
+        const parsed = SessionSchema.safeParse(baseSession({ activeAt: 42 }))
+        expect(parsed.success).toBe(true)
+        if (parsed.success) {
+            expect(parsed.data.activeAt).toBe(42)
+        }
+    })
+
+    it('coerces null activeAt to 0 without failing parse', () => {
+        const parsed = SessionSchema.safeParse(baseSession({ activeAt: null }))
+        expect(parsed.success).toBe(true)
+        if (parsed.success) {
+            expect(parsed.data.activeAt).toBe(0)
+        }
+    })
+
+    it('coerces missing activeAt to 0 without failing parse', () => {
+        const raw = baseSession()
+        delete (raw as { activeAt?: number }).activeAt
+        const parsed = SessionSchema.safeParse(raw)
+        expect(parsed.success).toBe(true)
+        if (parsed.success) {
+            expect(parsed.data.activeAt).toBe(0)
+        }
+    })
+})

shared/src/schemas.ts

@@ -212,7 +212,8 @@ export const SessionSchema = z.object({
     createdAt: z.number(),
     updatedAt: z.number(),
     active: z.boolean(),
-    activeAt: z.number(),
+    // Hub may still emit null for legacy SQLite rows; keep output type number.
+    activeAt: z.number().nullish().transform((value) => value ?? 0),
     metadata: MetadataSchema.nullable(),
     metadataVersion: z.number(),
     agentState: AgentStateSchema.nullable(),