From 1b481e4949146a57093ca7bc9731f4eb2ce00cd4 Mon Sep 17 00:00:00 2001
From: Ishaan Jaffer <ishaanjaffer0324@gmail.com>
Date: Wed, 6 May 2026 15:10:29 -0700
Subject: [PATCH] test(agent_session_endpoints): validate SSE resume +
 Last-Event-ID header (LIT-2877 #8)

---
 .../test_sse_resume.py                        | 115 ++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 tests/test_litellm/proxy/agent_session_endpoints/test_sse_resume.py

diff --git a/tests/test_litellm/proxy/agent_session_endpoints/test_sse_resume.py b/tests/test_litellm/proxy/agent_session_endpoints/test_sse_resume.py
new file mode 100644
index 00000000000..6da0e8d59e0
--- /dev/null
+++ b/tests/test_litellm/proxy/agent_session_endpoints/test_sse_resume.py
@@ -0,0 +1,115 @@
+"""
+Validation #8 — SSE resume.
+
+Read 3 events, kill, reconnect with starting_seq=3, get rest. No gaps,
+no dupes.
+
+Implementation note: we don't open a real long-running SSE stream — we
+shape the test as "given a run with N events, the events stream should
+emit exactly the unseen ones and close once the run is terminal." We
+check via the StreamingResponse body iterator with a finished run so
+the loop terminates quickly.
+"""
+
+import json
+import re
+
+from litellm.proxy.agent_session_endpoints.constants import (
+    EVENT_TYPE_RUN_FINISHED,
+)
+
+
+def _bootstrap_ready(client, noop_provider):
+    agent = client.post(
+        "/v2/agents",
+        headers={"Authorization": "Bearer k"},
+        json={"name": "t", "model": "gpt-4"},
+    ).json()
+    sess = client.post(
+        "/v2/sessions",
+        headers={"Authorization": "Bearer k"},
+        json={"agent_id": agent["id"], "repos": []},
+    ).json()
+    daemon_token = sess["daemon_token"]
+    sid = sess["id"]
+    client.post(
+        f"/v2/sessions/{sid}/internal/register",
+        headers={"Authorization": f"Bearer {daemon_token}"},
+        json={"vm_id": "i-noop"},
+    )
+    return sid, daemon_token
+
+
+def _seed_events(client, sid, daemon_token, count: int) -> str:
+    run = client.post(
+        f"/v2/sessions/{sid}/runs",
+        headers={"Authorization": "Bearer k"},
+        json={"prompt": {"text": "hi"}},
+    ).json()
+    rid = run["id"]
+    client.get(
+        f"/v2/sessions/{sid}/runs/next/internal/poll",
+        headers={"Authorization": f"Bearer {daemon_token}"},
+    )
+    for i in range(count):
+        client.post(
+            f"/v2/sessions/{sid}/runs/{rid}/events:append",
+            headers={"Authorization": f"Bearer {daemon_token}"},
+            json={"event_type": "log", "payload": {"i": i}},
+        )
+    # End the run so the SSE stream can quiesce + close.
+    client.post(
+        f"/v2/sessions/{sid}/runs/{rid}/events:append",
+        headers={"Authorization": f"Bearer {daemon_token}"},
+        json={"event_type": EVENT_TYPE_RUN_FINISHED, "payload": {"result": "done"}},
+    )
+    return rid
+
+
+def _parse_seqs(body_text: str):
+    return [int(m.group(1)) for m in re.finditer(r"^id:\s*(\d+)$", body_text, re.M)]
+
+
+def test_sse_emits_all_events_from_zero(client, noop_provider):
+    sid, daemon_token = _bootstrap_ready(client, noop_provider)
+    rid = _seed_events(client, sid, daemon_token, count=5)
+
+    res = client.get(
+        f"/v2/sessions/{sid}/runs/{rid}/events",
+        headers={"Authorization": "Bearer k"},
+    )
+    assert res.status_code == 200
+    seqs = _parse_seqs(res.text)
+    # Seqs 1..6 (5 logs + 1 run_finished)
+    assert seqs == [1, 2, 3, 4, 5, 6]
+
+
+def test_sse_resumes_with_starting_seq(client, noop_provider):
+    sid, daemon_token = _bootstrap_ready(client, noop_provider)
+    rid = _seed_events(client, sid, daemon_token, count=5)
+
+    res = client.get(
+        f"/v2/sessions/{sid}/runs/{rid}/events?starting_seq=4",
+        headers={"Authorization": "Bearer k"},
+    )
+    assert res.status_code == 200
+    seqs = _parse_seqs(res.text)
+    # starting_seq=4 means "last seen was 3, give me >= 4".
+    assert seqs == [4, 5, 6]
+
+
+def test_sse_last_event_id_header_takes_precedence(client, noop_provider):
+    sid, daemon_token = _bootstrap_ready(client, noop_provider)
+    rid = _seed_events(client, sid, daemon_token, count=3)
+
+    res = client.get(
+        f"/v2/sessions/{sid}/runs/{rid}/events",
+        headers={
+            "Authorization": "Bearer k",
+            "Last-Event-ID": "2",
+        },
+    )
+    assert res.status_code == 200
+    seqs = _parse_seqs(res.text)
+    # Last-Event-ID=2 means "give me > 2", so we expect 3 + 4 (run_finished).
+    assert seqs == [3, 4]