feat(/compress): manual session compression with focus topic — closes #469 (PR #619 by @franksong2702)

POST /api/session/compress with optional focus_topic. Transcript-inline cards: command, running, complete (collapsible green), reference. /compact alias kept. Fixes: var(--green) undefined color, focus_topic 500-char cap. Independent review by @nesquena (4 passes).

tests/test_sprint46.py

@@ -0,0 +1,157 @@
+"""
+Sprint 46 Tests: manual session compression with optional focus topic.
+"""
+
+import contextlib
+import io
+import json
+import sys
+import types
+
+from api.models import Session
+from api.config import SESSION_DIR
+from api.routes import _handle_session_compress
+from tests._pytest_port import BASE
+
+
+class _FakeHandler:
+    def __init__(self):
+        self.wfile = io.BytesIO()
+        self.status = None
+        self.sent_headers = {}
+
+    def send_response(self, status):
+        self.status = status
+
+    def send_header(self, key, value):
+        self.sent_headers[key] = value
+
+    def end_headers(self):
+        pass
+
+    def payload(self):
+        return json.loads(self.wfile.getvalue().decode("utf-8"))
+
+
+class _FakeCompressor:
+    def __init__(self):
+        self.calls = []
+
+    def compress(self, messages, current_tokens=None, focus_topic=None):
+        self.calls.append(
+            {
+                "messages": list(messages),
+                "current_tokens": current_tokens,
+                "focus_topic": focus_topic,
+            }
+        )
+        if len(messages) >= 2:
+            return [messages[0], messages[-1]]
+        return list(messages)
+
+
+class _FakeAgent:
+    last_instance = None
+
+    def __init__(self, **kwargs):
+        self.kwargs = kwargs
+        self.context_compressor = _FakeCompressor()
+        _FakeAgent.last_instance = self
+
+
+def _make_session(messages=None):
+    SESSION_DIR.mkdir(parents=True, exist_ok=True)
+    messages = messages or [
+        {"role": "user", "content": "one"},
+        {"role": "assistant", "content": "two"},
+        {"role": "user", "content": "three"},
+        {"role": "assistant", "content": "four"},
+    ]
+    s = Session(
+        session_id="compress_test_001",
+        title="Untitled",
+        workspace="/tmp/hermes-webui-test",
+        model="openai/gpt-5.4-mini",
+        messages=messages,
+    )
+    s.save(touch_updated_at=False)
+    return s.session_id
+
+
+def test_session_compress_requires_session_id(cleanup_test_sessions):
+    handler = _FakeHandler()
+    _handle_session_compress(handler, {})
+    assert handler.status == 400
+    assert handler.payload()["error"] == "Missing required field(s): session_id"
+
+
+def test_session_compress_roundtrip(monkeypatch, cleanup_test_sessions):
+    created = cleanup_test_sessions
+    sid = _make_session()
+    created.append(sid)
+
+    fake_run_agent = types.ModuleType("run_agent")
+    fake_run_agent.AIAgent = _FakeAgent
+    monkeypatch.setitem(sys.modules, "run_agent", fake_run_agent)
+
+    import api.config as _cfg
+    fake_runtime_provider = types.ModuleType("hermes_cli.runtime_provider")
+    fake_runtime_provider.resolve_runtime_provider = lambda requested=None: {
+        "api_key": "fake-key",
+        "provider": requested or "openai",
+        "base_url": "https://api.openai.com/v1",
+    }
+    fake_hermes_cli = types.ModuleType("hermes_cli")
+    fake_hermes_cli.__path__ = []
+    fake_hermes_cli.runtime_provider = fake_runtime_provider
+    monkeypatch.setitem(sys.modules, "hermes_cli", fake_hermes_cli)
+    monkeypatch.setitem(sys.modules, "hermes_cli.runtime_provider", fake_runtime_provider)
+    import hermes_cli.runtime_provider as _rtp
+
+    monkeypatch.setattr(
+        _cfg,
+        "resolve_model_provider",
+        lambda model: ("openai/gpt-5.4-mini", "openai", "https://api.openai.com/v1"),
+    )
+    monkeypatch.setattr(
+        _cfg,
+        "_get_session_agent_lock",
+        lambda sid: contextlib.nullcontext(),
+    )
+    monkeypatch.setattr(
+        _rtp,
+        "resolve_runtime_provider",
+        lambda requested=None: {
+            "api_key": "fake-key",
+            "provider": requested or "openai",
+            "base_url": "https://api.openai.com/v1",
+        },
+    )
+
+    handler = _FakeHandler()
+    _handle_session_compress(handler, {"session_id": sid, "focus_topic": "database schema"})
+
+    assert handler.status == 200
+    payload = handler.payload()
+    assert payload["ok"] is True
+    assert payload["focus_topic"] == "database schema"
+    assert payload["summary"]["headline"] == "Compressed: 4 → 2 messages"
+    assert payload["session"]["session_id"] == sid
+    assert payload["session"]["messages"] == [
+        {"role": "user", "content": "one"},
+        {"role": "assistant", "content": "four"},
+    ]
+    assert _FakeAgent.last_instance is not None
+    assert _FakeAgent.last_instance.context_compressor.calls[0]["focus_topic"] == "database schema"
+
+
+def test_static_commands_js_registers_compress_alias(cleanup_test_sessions):
+    from pathlib import Path
+
+    with open(Path(__file__).resolve().parents[1] / "static" / "commands.js", encoding="utf-8") as f:
+        src = f.read()
+    assert "name:'compress'" in src
+    assert "name:'compact'" in src
+    assert "/api/session/compress" in src
+    assert "cmdCompress" in src
+    assert "cmdCompact" in src